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The present work aims to study the effects of cold gas plasma on some quality parameters of apple slices belonging to four different cultivars (Pink Lady®, Fuji, Red Delicious and Modì®), with particular attention to polyphenoloxidase (PPO) inhibition and related changes in colour and visual quality. Upon plasma exposure a noticeable reduction of superficial browning was observed in all cultivars but not always proportionally to treatment time; the effect on PPO activity was very variable and not correlated to the effect on enzymatic browning. Textural parameters were affected by plasma treatments only in Red Delicious apples. Generally, the response of the tissue to the treatments was variable according to the cultivar considered. The results obtained in this study indicate the necessity of further investigation about consequences of plasma treatment on specific tissue physiology in order to choose the better treatment parameters, optimizing its effect for the specific final product. The application on cold plasma to minimally processed fruit and vegetable has shown a good potential for enzymatic browning inhibition making it an interesting alternative to traditional dipping methods. Nevertheless, the effect on the tissue to the exposure to plasma active particles is not fully known yet. For the industrial application of the treatment, the response for example of different cultivars to the treatment is of high importance, in the first place for the selection of the more appropriate raw material but also to eventually adapt the process parameters to the specificity of the matrix. • Fresh-cut apple of different cultivar was subjected to cold gas plasma treatment. • Generally enzymatic browning was inhibited not proportionally to treatment time. • Effect on PPO was variable and not consistent with enzymatic browning inhibition. • The effect of cold gas plasma treatment is strictly cultivar dependent. [ABSTRACT FROM AUTHOR]

A new method for rapid assessment of selected wine parameters based on a 1.6–2.7 GHz Waveguide Vector Spectrometer (WVS) is proposed for the first time. The Gain and Phase spectra of forty-two samples of Sangiovese red wines were acquired in the best frequency range (1.6–2.1 GHz) and modelled using Partial Least Square (PLS) regression to predict alcohol, dry extract and glycerol contents. The prediction of alcohol content showed test set validation R 2 values of 0.961 (RMSE = 0.11 mL/dL) and of 0.955 (RMSE = 0.13 mL/dL) for Gain and Phase spectra, respectively. Glycerol and dry extract were predicted at the best using Gain spectra with R 2 values of 0.834 (RMSE = 0.31 g/L) and 0.861 (RMSE = 0.51 g/L), respectively. A test was also conducted to assess the technique ability in the detection of alcohol and glycerol contents by preparing and using samples of model wines with known added content of these substances. R 2 values up to 0.992 (RMSE = 0.16 mL/dL) for alcohol and 0.999 (RMSE = 0.04 g/L) for glycerol contents were obtained using Gain spectra. The suggested technique has shown to be promising for the rapid assessment of the control process of these important attributes of wines. [ABSTRACT FROM AUTHOR]

A Waveguide Vector Spectrometer (WVS), operating in the frequency range 1.6–2.7 GHz, was designed, set up and tested for rapid assessment of main chemical-physical properties of a plurality of food products. The system, completely integrated, includes a waveguide, a control unit, a signal generator, a gain/phase comparator, a power supply, and a USB port (for control and data transfer). The information contained in the gain and phase waveforms related to the product dielectric properties are exploited for the prediction of different compounds characterising both simple liquid solutions and more complex food products. By processing spectral data with Partial Least Square Regression (PLS) algorithm, high levels of prediction accuracy were observed for all the tested products (R 2 values from 0.940 to 0.999, in validation). Generally, both gain and phase waveforms appeared to be effective, for the selected foods, in terms of prediction accuracy. On the whole, the proposed system seems able to assess the content of varied substances both on simple and complex matrices. Simple prospective changes of the sample holder make the equipment potentially suitable for on-line monitoring of the quality of food products. [ABSTRACT FROM AUTHOR]

Pulsed electric field (PEF) technology is gaining momentum as a pre-treatment to enhance mass transfer of vegetable tissues obtained by further processing. In this study PEF pre-treatment increased osmotic dehydration (OD) effectiveness, in terms of water loss and solid gain in apples, as a function of electric field strength and number of pulses. Mass transfer was particularly high when average electric fields of 250 and 400 V cm -1 were applied. Time domain nuclear magnetic resonance (TD-NMR), with the use of a contrast agent, clarified structural changes that drive mass transfer. Treatments at 100 V cm -1 redistributed water between vacuole, cytoplasm and extracellular space, while at 250 and 400 V cm -1 the membrane breakages caused the loss of cellular compartmentalization. Two non-destructive and fast acquirable parameters, the longest measured relaxation time (T 2 ) and water self diffusion coefficient (D w ), allowed the separate and accurate observation of PEF treatment and osmotic dehydration effects. Industrial relevance The developed non-destructive method, here described, allows the measure of the effects of PEF treatment on apple tissue which can be exploited to have reliable control of the process within minutes. Since mass transfer parameters depend on subcellular water redistribution, the present work provides a tool to boost the development and optimization of agri-food processes on fresh vegetable tissues. [ABSTRACT FROM AUTHOR]

The decontamination efficacy of a dielectric barrier discharge (DBD) gas plasma generator equipped with four different interchangeable electrode materials (stainless steel, brass, silver and glass/brass) was tested towards Listeria monocytogenes 56Ly and Escherichia coli NCFB 555. Bacteria were suspended in sterile saline solutions and placed for 20, 40 and 60 min under the discharge generated at atmospheric conditions by using air as the working gas. Significant differences emerged only for L. monocytogenes (after 40 and 60 min). Highest reductions (up to about 8 log CFU/ml) were observed by using the silver and brass electrodes after 60 min. Differences in terms of electrical parameters (voltage, current, active power) and chemical species generated in the liquid medium (nitrites and nitrates concentrations) were not significant, relevant or directly attributable to the decontamination efficacy of the different electrodes. Ozone production was higher for oxidation-resistant electrode materials. The decontamination effect was influenced by silver and brass antibacterial properties. Industrial relevance The results of the present work, focused on the impact of the electrode material on the decontamination performance, introduced a new aspect in the technology panorama that could improve possible industrial application. The selection of the electrode material played a role in terms of decontamination efficacy. [ABSTRACT FROM AUTHOR]

Dairy industry has a strong interest in quick and inexpensive techniques able to estimate milk fat content both in off and on-line processes. In the present study, a simple and inexpensive optical technique is preliminary described, discussed, and then tested for the prediction of this parameter. It's essentially based on the different intensity and spectral emission of a tungsten lamp during its progressive lighting combined with the photodiode wavelength sensitivity. Measurements were carried out at 22 °C on thirteen samples of commercialized milk (and mixture of them) (fat content ranging from 0.05% to 3.8%). The influence of the milk temperature on the optical behaviour was also investigated. The detected voltage waveform was strictly and not-linearly correlated with the fat content (R 2 up to 0.985) and predictions with R 2 up to 0.997 were obtained by using artificial neural networks (ANN). Milk temperature differently influenced the measurements for milks with various fat content. [ABSTRACT FROM AUTHOR]

On or off-line controls of the freezing process, used to ensure the desired final quality of frozen dairy desserts, is an important task, especially for manufacturers who consider the standard of production as a primary goal. One of the products of interest in this context is the milkshake, a drink that contains ice crystals and a precise content of air. Herein, we used three different techniques, based on as many prototypes, to monitor and control the freezing process of a milkshake based product over a period of 1–29 h: an optical technique based on a digital microscope and image analysis, a rotational rheometer and a capacitive device. The optical technique characterized crystal growth and air content during freezing, and can be regarded as a reference method. The dimension of ice crystals and content of air bubbles showed a non-linear increase during preparation time. Correlations were high, with coefficients of determination up to 0.991. Parameters measured by other techniques, such as a rotational rheometer and a capacitive device, also showed good, logarithmic correlations with freezing time, with R 2 values up to 0.964. Correlations between the main freezing parameters and data obtained with the rotational and capacitive techniques appeared good ( R 2 up to 0.983). Thus, these latter techniques might conceivably replace more complicated and expensive optical methods used to monitor the freezing process, especially when processing a product characterized by a constant composition. [ABSTRACT FROM AUTHOR]

The frozen eggplant was studied using absorption isotherms, measured by using saturated salt solution in desiccator chamber (DES) and the Dynamic Vapor Sorption (DVS) instrument. Melting temperature and glass transition temperature were determined by differential scanning calorimetry (DSC), while mechanical properties were determined by a compression test. In addition, dielectric properties were assessed by means of two instrumental chains to cover a wide frequency range of radiofrequencies. Absorption fitting was able to estimate unfreezeable water content, while the dynamic instrument showed a hysteresis between adsorption and desorption, confirming amorphous materials' presence in the products. Thermograms revealed two phase transition apparent TgIII and TgII affected by the plasticizing effect of water. Mechanical properties confirmed the water influence on structures, as Fermi model fitting (R2 = 0.984, RMSE = 3.9 N) shown. Dielectric properties were carried out to allow the description of three main dispersion α, β, and γ relaxations. State diagram was developed to show different zones corresponding to possible physical structures. [ABSTRACT FROM AUTHOR]

The non-destructive assessment and control on and off-line of some quality parameters of the grated cheese is a goal of the dairy industries and distributors. The present research is addressed to explore the possibility of estimating the percentage of moisture, proteins, added rind, and the ripening time of this kind of cheese by a capacitive technique supported by basic statistical analysis and artificial neural networks (ANN). An instrumental chain composed by a parallel plate capacitor probe, for housing the cheese in a suitable container, and a LCR meter, were used to measure the capacitance of different product mixtures, in the frequency range from 100 Hz to 10 kHz. Samples were prepared by mixing cheeses ripened from 8 months to 36 months and rind percentage from 0% to 50%. The results show that moisture and protein percentages can be estimated in a quite good manner with a linear correlation ( R 2 up to 0.81) and ANN ( R 2 up to 0.83). The ripening time is well linearly assessed in the cheese without the addition of rind ( R 2 = 0.994) or if the rind percentage is known ( R 2 from 0.872 to 0.963). The rind percentage is very well linearly estimated if the ripening time is known ( R 2 from 0.914 to 0.987). Estimation of the rind percentage if the ripening time is unknown appears more difficult (max R 2 = 0.658) because both ripening and addition of rind involve a decrease in capacitance. The frequency at which the capacitance is measured shows only a weak influence in the goodness of the parameters determination. On the whole and as a trend, the correlations improve increasing the frequency. The obtained results, the conformation of the probe and the minimal data treatments mean that this technique can be considered to be applied in the chains of the grated cheese packaging. [ABSTRACT FROM AUTHOR]

Abstract: The present research investigated the correlations between capacitance and water content of extra virgin olive oils (EVOO). A commercial capacitor probe for radio applications and an LCR meter were used for electric tests in the frequency range from 500Hz to 512kHz. Seventeen samples of different EVOO with a moisture content ranging from 178 to 1321mg/kg oil were selected for study. To assess the influence of moisture only, the oil with the maximum water content was filtered down to 288mg/kg oil and five samples with intermediate water contents were prepared and submitted to electrical measurements. Subsequently, the capacitance of all 17 EVOO samples was measured at selected frequencies. Water content and capacitance for filtered oil were linearly correlated, showing R 2 values up to 0.959 and a root mean square error (RMSE) of 48mg/kg oil at 2kHz. When the main oil composition together with the moisture changed, the trend was always linear, but the correlation (R 2) decreased to 0.818 with an RMSE value of 123mg/kg oil (at 8kHz), so that the system remains suitable for screening of water content. Strong correspondences between capacitance and impedance suggest that these measurements can be carried out with very simple instruments for measuring voltage and current. Some novel linear correlations also emerged between water content, capacitance and fatty acid composition. [Copyright &y& Elsevier]

Abstract: Parmigiano–Reggiano (P–R) cheese is still one of the most valuable Protected Designation of Origin (PDO) cheeses of Italy. The rind percentage (from 12% to 50%), the ripening (from 13 to 31months), the moisture content and the differences between true P–R and competitors were determined by means waveguide spectroscopy. Preliminary tests were carried out in the 2–20GHz frequency range (with a span of 1GHz) to investigate which 1GHz frequency range contains most information on the rind percentage and on the months of ripening. Partial Least Squares (PLS) regression was used to predict rind percentage, months of ripening and moisture in the previously selected frequency ranges (2–3, 5–6 and 17–18GHz for the rind percentage; 2–3, 5–6 and 16–17GHz for the months of ripening). Moreover, Soft Independent Modelling of Class Analogy (SIMCA) analysis was used to discriminate the samples according to the rind percentage. Principal component analysis (PCA) was used to discriminate true P–R cheese from competitors. PLS models (test set validation) showed R2 values up to 0.944 (root mean square error of prediction in test set validation, RMSEp =3.4%), 0.966 (RMSEp =1.2months) and 0.786 (RMSEp =0.99%) for the prediction of rind percentage, months of ripening and moisture percentage, respectively. As a result only a part of the prediction of rind percentage and ripening can easily be attributed to the moisture. For each considered frequency range, all samples belonging to the classes characterized by 12% and 50% of rind were correctly classified. Competitors were clearly separated from P–R cheese by the PCA analysis of the spectral signals and their moisture was predicted with a R 2 values up to 0.942 (test set validation). In this case, the discrimination power can be mainly attributed to moisture content. [Copyright &y& Elsevier]

Abstract: In the present research we discuss a novel way to set up a predictive method for determining the water content of oil based on the Partial Least Squares (PLS) regression analysis of reflectometric signals. Ten different extra virgin olive oils with a water content ranging from 714 to 2008mg of water/kg of oil were submitted to reflectometric measurement by means of a hand made probe connected to a digital sample oscilloscope with TDR functions interfaced with a PC. Limits of the classical approach based on the TDR electromagnetic theory in the prediction of these small water content differences were also discussed. The results show that the suggested novel approach is able to predict the water content of very small quantities of oil (1.8g) in a 3ml translucent disposable PE cuvette by means of PLS regressions characterized by R 2 value up to 0.984 and a root mean square error of prediction of about 55mg of water/kg of oil. The temporal region showing the best information content corresponded with the rise of the reflection of the probe end, but information highly correlated with the water content can be extracted from other temporal regions of the entire TDR signal. [Copyright &y& Elsevier]

Abstract: Soluble solids content (SSC) and Magness–Taylor flesh firmness (MTf) of “Hayward” kiwifruits were non-destructively assessed by means of a waveguide, that houses the fruit, connected to a sweeper oscillator and a spectrum analyzer. A preliminary test was conducted with a plastic fruit filled with solutions with different SSC values in the frequency range from 2 to 20GHz (with a step of 1GHz). The best linear correlations (R 2 up to 0.987) between electric signals and SSC solutions in the above described test were found in the 2–3GHz and 15–16GHz steps. These steps were used for the dielectric measurements on kiwifruit samples during storage of 28days at 14°C. Partial least squares (PLS) regression were then used to predict SSC and MTf from these acquired spectra. In “test set” validation, PLS models showed R 2 values up to 0.804 (RMSE=0.98°Brix) and 0.806 (RMSE=8.9N) for the prediction of SSC and MTf, respectively. [Copyright &y& Elsevier]

Abstract: In the present research, a method based on admittance measurements able to assess total solids and fat contents (%) in nine different liquid whole egg products was set up. By means of a tetrapolar platinum cell connected to a signal conditioning circuit, an alternating current generator and a data acquisition system, the effect of 15 different combinations of frequencies of the oscillating field (10, 100, 500, 1000 and 5000Hz) and input voltage levels (1, 1.5 and 2V) on the estimation of the total solids and fat contents were analyzed. The influence of the temperature solution on the electrical measurements was also assessed. The best estimations were obtained at 1000Hz and 1V (R 2 =0.998; SE=0.14%) for the total solids content and at 5000Hz and 1V (R 2 =0.995; SE=0.19%) for the fat content. For both parameters, the measurements conducted at 10Hz appeared affected by the polarization occurring at the electrodes-solution interface. The admittance of the liquid whole egg products linearly increased with the temperature, and a temperature coefficient θ at 20°C of about 2.1 was calculated. These excellent results encourage an industrial application of the technique for a rapid and economic assessment of the total solids and fat contents in the liquid egg products. [Copyright &y& Elsevier]

Abstract: The input of a waveguide probe for shell eggs was connected to a sinewave sweeper oscillator and the signal at the output was captured by a spectrum analyser. A first analysis was carried out in the range from 3 to 20GHz with a span of 1GHz to investigate which 1GHz frequency range contains most information for predicting the main quality indices of eggs during 15days of storage. Simple linear regression models were therefore set up and the coefficient of determination was calculated. The absorbance spectra in the range thus identified (from 10.5 to 11.5GHz) were used to predict the quality indices by means of an artificial neural network (ANN). The R 2 values of the obtained ANN in validation mode were 0.918, 0.854 and 0.912 for the air cell, the thick albumen height and the yolk index, respectively. The correlations between the quality parameters and tests carried out on albumen, yolk and plastic eggs for simulating the air cell showed how one index can be indirectly predicted through another one. [Copyright &y& Elsevier]

Abstract: A resistive barrier discharge (RBD) prototype able to generate gas plasma at atmospheric conditions was set up. The discharge was electrically characterized and the plasma glow was analysed by optical emission spectroscopy. The decontamination power of the device was assessed on samples of shell eggs experimentally inoculated with Salmonella Enteritidis and Salmonella Typhimurium (5.5–6.5 Log CFU/eggshell) and placed in the treatment chamber. Different decontamination times (10, 20, 30, 45, 60 and 90min) and relative humidity values (RH) of the gas mixture in the chamber (i.e. 35% and 65%, at 25°C) were considered. All samples were treated in the plasma after-glow chamber where the measured temperature was not much higher than the room temperature, minimizing the risk of egg quality alterations. The discharge was characterized by a potential difference of about 15kV; the emission spectra showed the presence of very reactive species such as the positive ion and OH and NO radicals. After 90min of treatment, reductions up to 2.5 Log CFU/eggshell and 4.5 Log CFU/eggshell were observed for S. enteritidis using air with low and high moisture contents, respectively. No significant negative effects of the gas plasma were observed on the egg quality traits. [Copyright &y& Elsevier]

Abstract: The device used in the present study consists of a conveyer belt that throws the fruit onto a flat horizontal plate connected to a load cell. The vertical distance between plate and conveyer belt (drop height) as well as the speed of the belt can be continuously adjusted. Tests were carried out by selecting three different values of drop height and speed. The Magness-Taylor (MTf) index was used as reference, destructive parameter, to describe the flesh firmness and to set-up predictive models. The digitalized time history of the force was analysed to extract some mechanical indices (peak force, impact duration and impulse) used to predict MTf by simple or multiple regression analyses. Moreover, each point of the entire time history was processed by artificial neural network (ANN) software to predict MTf. The goodness of fit, expressed as R 2, was up to 0.823 with the regression models. On the whole, the peak force was the best predictor. The ANNs did not involve a substantial increase in goodness of fit with respect to the best regression models: +8.3%, as mean, 37% as maximum. The speed or position at which the fruit impacts the plate can represent an important parameter influencing the MTf prediction. Free dropping of the fruit instead of throwing onto the plate by the conveyer did not provide a better prediction. The impact device did not cause mechanical damage to the kiwifruits. [Copyright &y& Elsevier]

The present study investigates the possibility of predicting the main quality indices of shell eggs by means of a dielectric technique based on a capacitor probe and a fully integrated RF circuit for measuring the amplitude and phase differences between two independent input signals. Samples of eggs were submitted to dielectric measurements in the range 50–500MHz after 1, 2, 4, 8, and 15 days of storage at room temperature (20°C). Immediately after testing, the air cell and the thick albumen heights, the Haugh unit and the yolk index of eggs were destructively measured. Statistical models obtained by processing dielectric spectra and quality indices determined by means of partial least square (PLS) analysis showed coefficients of determination (R 2) values up to 0.996 for the time of storage, 0.876 for the air cell height, and 0.678 for the thick albumen height. Accurate predictions were also obtained for models based on selected narrow spectral regions. [Copyright &y& Elsevier]

Abstract: Changes of the dielectric parameters of fresh hen eggs during storage were investigated for the development of a method to assess the main quality indices. Dielectric constant (ε′) and loss factor (ε″) were measured in the frequency range 20–1800MHz using an open-ended coaxial probe on thick albumen and yolk of eggs after 1, 2, 4, 8 and 15 days of storage at room temperature. Tests were also carried out at the 9th day of storage to compare dielectric properties of thick and thin albumen. Statistical analysis was performed at 20, 100, 400, 900 and 1800MHz. Thick and thin albumen showed slight differences in dielectric properties but significant only for ε″ at 900MHz. Dielectric constant and loss factor of yolk generally increased with the storage time. The maximum increment from the 1st to the 15th days of storage (22%,) was registered for ε″ at 20MHz. Methods based on the comparison between the experimental ε″ and calculated values by means of conductivity and frequency can potentially be used in predicting eggs’ age. [Copyright &y& Elsevier]

Monitoring the quality attributes of grapes is a practice that allows the state of ripeness to be checked and the optimal harvest time to be identified. A non-destructive method based on hyperspectral imaging (HSI) technology was developed. Analyses were carried out directly in the field on a 'Sangiovese' (Vitis vinifera L.) vineyard destined for wine production, by using a Vis/NIR (400–1000 nm) hyperspectral camera. One vineyard row was analysed on 13 different days during the pre-harvest and harvest time. The soluble solids content (SSC) expressed in terms of °Brix was measured by a portable digital refractometer. Afterwards, the grape samples were split in two classes: the first one composed by the samples characterised by a °Brix lower than 20 (not-ripe), while the second one by the samples with a °Brix higher than 20 (ripe). Grape mean spectra were extracted from each hyperspectral image and used to predict the SSC by partial least squares regression (PLS), and to classify the samples into the two classes by PLS discriminant analysis (PLS-DA). SSC was predicted with a R2 = 0.77 (RMSECV = 0.79 °Brix), and the samples were correctly classified with a percentage from 86 to 91%. Even if the number of wavelengths was limited, the percentages of correctly classified samples were again within the above-mentioned range. The present study shows the potential of the use of HSI technology directly in the field by proximal measurements under natural light conditions for the prediction of the harvest time of the 'Sangiovese' red grape. • To identify the optimal ripening time the grape quality parameters were monitored. • In-field Vis/NIR hyperspectral imaging was used. • Regression model to predict soluble solid content was developed. • The grape samples were classified into two classes: not-ripe and ripe. • The classification performance remained unchanged by reducing the number of wavelengths. [ABSTRACT FROM AUTHOR]

• An innovative protein stabilization method for white wines has been developed. • The TiO 2 in nanoporous form is selective for i unstable proteins removal. • The treatment didn't adversely affect the wine quality. • The TiO 2 treatment enhanced defense against oxidation under oxygen supply. • The continuous flow treatment is best suited for industrial transfer. In this work the impact of an innovative protein stabilization method (TiO 2 -based composite sorbent material coupled with a prototype device operating under continuous flow) has been tested in terms of protein and oxidative stability of white wines. Optimal process parameters (duration 60 min; flow rate 1.5 ± 0.1 L/h in 6 cycle rates/h) ensured an average 32.5 % reduction of total proteins; the nanoporous TiO 2 film supported on inert glass beads acted as selective sorbent for pathogenesis-related proteins (PRPs, 10–60 kDa) responsible for wine instability, based on the protein stability studies (heat-test) performed in the experimental wines. The stabilization process has been tested for the release of contaminants (Ti), and the innovative treatment has been proven to preserve wine from oxidation also delaying the browning onset under extreme storage conditions. [ABSTRACT FROM AUTHOR]

A cheap technique based on an open-ended coaxial probe together with a vector network analyzer was set up. The vector network analyzer NanoVNA, a very tiny handheld device, is the affordable component that gives the instrumental chain a cost-effective perspective. The open-ended coaxial probe is a cable with an SMA gold-plated termination. User-friendly programs can be used to calibrate the instrument, carry out the measurements, and save data on PC. Simple liquid solutions (sodium chloride, citric acids, and saccharose) and more complex liquid food (milk, egg products, and fruit juice) were investigated. In addition, the temperature on the electric measurement of milk was measured to evaluate a possible influence for refrigerated storage products. The reflection parameters, such as the real and imaginary parts of S11, were used to build univariate and multivariate models. The best results in terms of coefficient of determination and related error were 0.997 (RMSE 0.05%) for sodium chloride and 0.965 (RMSE 0.71 °Brix) for fruit juice considering the univariate model, and 0.997 (RMSE 0.04%) for sodium chloride and 0.981 (RMSE 4.44%) for yolk using multivariate analysis. The proposed solution is non-destructive, cheap, rapid, and very attractive for potential lab and industrial applications. [ABSTRACT FROM AUTHOR]

• System mobility of green and roasted coffee was studied. • Glass transition and dielectric spectroscopy were evaluated. • Water and glycerol are the main plasticizing agents. Solid and liquid components coexist into glassy and amorphous structures of food complex matrixes. Both states admit movements, promoting physical modifications to a more thermodynamically stable system. Green and roasted coffee beans are principally characterized by a glassy structure that slowly evolves during storage. The aim of this study was to assess calorimetric and dielectric properties in combination, as a useful multi-analytical technique to improve the understanding of the motion mechanism of localized molecules. After equilibration at different water activities (a w) for the determination of sorption isotherms of green and roasted coffee, the glass transition temperature (Tg) of the samples has been measured by using differential scanning calorimetry (DSC). Increasing the a w from 0.155 to 0.512, the Tg shifted from 48.76 (±0.04) to 34.89 (±0.02) °C for green coffee and from 45.73 (±0.05) to 40.15 (±0.10) °C for the roasted one. The spectroscopic fingerprint of the matrix has been determined by dielectric measurements in terms of "gain" spectra (related to the imaginary part of permittivity). The maximum values of the determination coefficient (R2), obtained by linear correlation between spectral data and water activity or glass transition values for a specific frequency of the whole range (1.6 GHz–2.7 GHz), were 0.999 and 0.943 for green, and 0.997 R2 and 0.925 R2 for roasted coffee respectively. [ABSTRACT FROM AUTHOR]

Monitoring the quality attributes of grapes is a practice that allows the state of ripeness to be checked and the optimal harvest time to be identified. A non-destructive method based on hyperspectral imaging (HSI) technology was developed. Analyses were carried out directly in the field on a 'Sangiovese' (Vitis vinifera L.) vineyard destined for wine production, by using a Vis/NIR (400–1000 nm) hyperspectral camera. One vineyard row was analysed on 13 different days during the pre-harvest and harvest time. The soluble solids content (SSC) expressed in terms of °Brix was measured by a portable digital refractometer. Afterwards, the grape samples were split in two classes: the first one composed by the samples characterised by a °Brix lower than 20 (not-ripe), while the second one by the samples with a °Brix higher than 20 (ripe). Grape mean spectra were extracted from each hyperspectral image and used to predict the SSC by partial least squares regression (PLS), and to classify the samples into the two classes by PLS discriminant analysis (PLS-DA). SSC was predicted with a R2 = 0.77 (RMSECV = 0.79 °Brix), and the samples were correctly classified with a percentage from 86 to 91%. Even if the number of wavelengths was limited, the percentages of correctly classified samples were again within the above-mentioned range. The present study shows the potential of the use of HSI technology directly in the field by proximal measurements under natural light conditions for the prediction of the harvest time of the 'Sangiovese' red grape. • To identify the optimal ripening time the grape quality parameters were monitored. • In-field Vis/NIR hyperspectral imaging was used. • Regression model to predict soluble solid content was developed. • The grape samples were classified into two classes: not-ripe and ripe. • The classification performance remained unchanged by reducing the number of wavelengths. [ABSTRACT FROM AUTHOR]

The internal quality of kiwifruit, in terms of soluble solid content (SSC), flesh firmness (FF), and dry matter (DM), is widely recognised as a key feature for fruit sorting and pre-harvest assessment. Furthermore, flesh hue (FH) is another important parameter to consider for yellow flesh kiwifruits. NIR and VIS/NIR spectroscopic techniques are valuable alternatives for rapid and non-destructively prediction of all these quality parameters in fruit. Accordingly, the aim of this work was to build a partial least square (PLS) regression models to estimate SSC, FF, FH, and DM of yellow fleshed Actinida chinensis (Jintao) starting from Vis/NIR hyperspectral imaging (400–1000 nm) and FT-NIR (800–2500 nm) spectroscopy data. To take advantage of the complementary information of the two different spectral ranges, data fusion strategies were investigated to concatenate the data before PLS models. In particular, two different sequential fusion methods were used: low-level data fusion based on the concatenation of the pretreated spectra, and mid-level feature fusion characterised by the concatenation of features (scores) obtained by principal component analysis (PCA) or PLS models developed considering individually each data set. For all quality parameters, the best results were achieved by adopting the second approach of mid-level data fusion (PLS scores), reporting R P 2 (test set validation) of 0.914 (RMSEP=0.97°Brix), 0.843 (RMEP=1.82°H), 0.866 (RMSEP=9.41N), and 0.854 (RMSEP = 0.64%) for SSC, FH, FF, and DM, respectively. Furthermore, with respect to the PLS models from the individual data sets, the results reported a mean RMSEP reduction of 16.0 ± 4.8%, confirming the potential of the data fusion in improving the PLS prediction power for the quality parameter of kiwifruit. • Vis/NIR HSI and NIR spectroscopy were used to predict the yellow kiwifruit quality. • Regression models were developed to estimate SSC, FF, FH and DM. • Low and mid data fusion were investigated to concatenate the data before PLS models. • For all parameters, the best results were achieved by mid-level data fusion. • Results confirm the data fusion potential in improving the PLS prediction. [ABSTRACT FROM AUTHOR]

The optimal application of Pulsed Electric Fields (PEF) technology, used by food industry to assist mass transfer processes, depends on the effectiveness of the induced electroporation. The present work aimed at exploring the application of Magnetic Resonance Imaging (MRI) combined with Computer Vision System (CVS) analysis to assess the spatial distribution of electroporation in apple tissue. PEF-treated apple samples were compared with Dipping (Dip) and Vacuum Impregnation (VI) to gain insight into the spatial distribution of mechanisms that lead to microstructural modifications over time. CVS showed that electroporation modified heterogeneously apple microstructure, causing enzymatic browning unevenly across the samples. MRI transverse relaxation times (T 2 ) maps and longitudinal relaxation times (T 1 )-weighted images throughout apple tissue confirmed the inhomogeneous distribution and extent of the cell disruption, along with the release of intracellular content toward the external solution. Industrial relevance The novel applications of pulsed electric fields require fast and reliable methods to detect and estimate the breakage of the membranes integrity in order to boost their industrial adoption and optimization. The present study provided analytical tools able to monitor the spatial distribution of electroporation in plant tissue samples within minutes and consequently to speed up and improve the assessment of different PEF treatments. [ABSTRACT FROM AUTHOR]

In the present work, a nondestructive device set up for a rapid and reliable freshness assessment of rainbow trout during 10 days of storage in ice was evaluated. The device was characterized by a vector network analyzer interfaced with an open coaxial probe to be placed in contact with the fish eye. The acquisition of the reflected scattering parameter (S11), which is the ratio between the amplitude of the reflected and the incident signal, was assessed in the 50 kHz–3 GHz spectral range. S11 is composed of a real part and an imaginary part, and both parts were used to predict quality index method for freshness evaluations. Partial least squares regression predictive models of the demerit scores related to fish eye attributes (eye pupil and eye shape) and the day of storage were set up. The main results showed that both the real and imaginary parts of the S11 decrease as a function of storage time. The combination with multivariate analysis allowed to set up predictive models of the storage time and the demerit scores with R2 values up to 0.946 (root mean square error [RMSE] = 0.88 days) and 0.942 (RMSE = 3.17 demerit scores related to the fish eyes attributes), respectively (external validation). According to our results, the proposed cheap solution appears a useful tool for the freshness assessment of rainbow trout. Practical Application: This work shows that dielectric properties have the potential to discriminate stored fish according to their freshness quality. A device based on this principle can play a significant role in the postharvest processes, contributing to higher product quality and safety and supporting producers and retailers during the qualitative inspections. [ABSTRACT FROM AUTHOR]

Cassava starch (CS) and chitosan (CH) are biopolymers used alone or blended (CS/CH) to produce films, thanks to their excellent film-forming properties. Their main physical properties have been characterized, but their physical and water state have not yet been studied. The objective of this research was to study the water and macromolecular physical state of CS, CH and CS/CH films by DSC and dielectric properties, after sorption isotherms determinations. Biopolymers and obtained films were also analyzed by SEM, FTIR, X-ray diffraction and gas permeability. Dielectric properties of active films containing pitanga leaves hydroethanolic extract were also analyzed. All films presented type II sorption isotherms. Glass transition temperature of films decreased with the increase of moisture content (X w) following the Gordon and Taylor model. The dielectric constant behaves depending of the monolayer moisture content (X m): increased linearly as a function of X w when X w > X m. For X w ≤ X m , the dielectric constant remained constant. An exponential relationship between α-relaxation and Tg was calculated. • Cassava starch and chitosan produces homogenous and high gas barrier films. • Films moisture content (X w) varied with water activity according to the GAB model. • Films glass transition temperature varied with X w following the Gordon & Taylor model. • Dielectric constant increased linearly with X w for above the water monolayer. • α-relaxation reduced exponentially as a function of glass transition temperature. [ABSTRACT FROM AUTHOR]

Pulsed electric field (PEF) treatments can induce metabolic stress responses in plant tissue as a function of the applied conditions. This study highlighted the metabolic effects of reversible and irreversible electroporation in fresh-cut apple tissue, by adjusting the electric field strength to 100, 250 and 400 V/cm (100 μs pulse width, 60 pulses, 100 Hz). Metabolic heat, O 2 and CO 2 gas analysis, along with metabolomics, were employed to jointly evaluate the PEF-induced effects after 24 h at 10 °C. Marked metabolic changes were registered when the threshold of irreversible electroporation was exceeded, at 250 and 400 V/cm. With such treatments, a drop of metabolic heat and respiration rate was observed, as a probable consequence of the loss of the cell viability, anaerobic respiration pathways were noticeably lowered, while γ-aminobutyric acid metabolism was activated. Conversely, minimal modifications of the metabolism heat and metabolites concentrations were noticed when 100 V/cm was applied. Industrial relevance Metabolic response of fresh-cut fruit and vegetables as function of the manufacturing process is a fundamental aspect directly related to the quality of the final products. Pulsed electric fields (PEF), as well as other innovative technologies, can induce undesired effects on tissue metabolism that might limit the industrial application. Furthermore, the analytical methods used in the present work provide useful tools for the optimization of the PEF treatment conditions for fresh-cut manufacturers. [ABSTRACT FROM AUTHOR]

It is well known that a capacitor can recover part of the charge due to previous polarization after it was quickly shorted. Stretched exponential or power law currents referred to as Kohlrausch dielectric relaxation and described as empirical Curie-von Schweidler law have often been observed. To date, experimental studies on dielectric relaxation have been carried out with small capacitances and for a short time. The present paper shows the results of an experiment conducted with 3300 μF aluminum wet electrolytic capacitors for 95 days at a constant temperature (25°C). After some time had passed where we could distinguish the imprint of stretched power or exponential decay, in some of the tested capacitors the voltage did not decrease and even rose. In a few capacitors, a decay was not detected from the beginning to the end of storage. Measurements conducted with different dissipative loads demonstrated the linear dependence of this voltage on the resistance. Further measurements from 20 to 40°C demonstrated that this current is temperature dependent. The ability of a capacitor to show an increase of charge even if shunted with a dissipative load was found to be correlated with its leakage current. Logistic models to predict this behavior are presented. [ABSTRACT FROM PUBLISHER]

The freshness of anchovies (Engraulis Encrasicolus) was estimated by radio-frequency and optical techniques in order to propose non-destructive and objective methods for rapid screening. Measurements were conducted until 7 days at 0 °C, storing the fish under ice. Image analysis, dielectric spectroscopy and hyperspectral images were conducted on fish eyes whilst mechanical properties were measured on the fish body. Evaluation of images by RGB scale highlighted differences due to ageing. Maximum force decreased as a function of degradation process time. Cluster analysis on dielectric spectra and 3D-principal component analysis on hyperspectral images of fish eyes revealed a good ability to characterise ageing modification demonstrating suitable methods for the development of a non-destructive, and rapid system for evaluation of fish freshness. [Display omitted] • Anchovies freshness was measured by dielectric spectroscopy & hyperspectral imaging. • Dehydration of anchovy eyes was exploited for ageing estimation. • Multivariate approaches allowed to group the samples according to storage days. • Both techniques are rapid and contactless being promising for practical application. [ABSTRACT FROM AUTHOR]

Rapid, non-destructive fruit sorting techniques are increasingly being adopted to ensure that producers, industry, and consumers receive products that meet their quality requirements. Quality attributes typically used to assess fruit ripeness include soluble solids content (SSC) and flesh firmness (FF). In this study, hyperspectral imaging operating at 400–1000 nm (Vis/NIR) was adopted to evaluate the ripeness degree of 'Hayward' kiwifruit. Partial least square (PLS) regression models were developed to estimate SSC and FF, while two different types of PLS discriminant analysis (PLS-DA) were used to classify samples according to three repining classes (defined on the base of SCC and FF values). To reduce the computation complexity, and simplify the calibration models, two variable selection methods (genetic algorithm GA, and variable importance in projection VIP) were adopted. For SSC, the prediction R2 values ranged from 0.85 (RMSE = 1.10 °Brix) to 0.94 (RMSE = 0.73 °Brix), and for FF from 0.82 (RMSE = 14.51 N) to 0.92 (RMSE = 9.87 N). Classification sensitivity reached values of 97% and 93%, for the model considering the SCC and FF classes, respectively. Prediction and classification performances remained substantially unchanged by reducing the number of wavelengths. Therefore, hyperspectral imaging appears to be suitable for prediction of kiwi quality attributes and their classification. • Hyperspectral imaging to assess kiwi ripening stage rapidly and non-destructively. • GA and VIP methods to select the variables (wavelengths). • PLS regression models to predict quality attributes SSC and FF. • PLS-DA and soft PLS-DA to classify fruit by predefined SSC and FF classes. [ABSTRACT FROM AUTHOR]

The fruit industry needs rapid and non-destructive techniques to evaluate the quality of the products in the field and during the post-harvest phase. The soluble solids content (SSC), in terms of °Brix, and the flesh firmness (FF) are typical parameters used to measure fruit quality and maturity state. Hyperspectral imaging (HSI) is a powerful technique that combines image analysis and infrared spectroscopy. This study aimed to evaluate the potential of the application of the Vis/NIR push-broom hyperspectral imaging (400 to 1000 nm) to predict the firmness and the °Brix in apricots (180 samples) during storage (11 days). Partial least squares (PLS) and artificial neural networks (ANN) were used to develop predictive models. For the PLS, R2 values (test set) up to 0.85 (RMSEP=1.64 N) and 0.72 (RMSEP=0.51 °Brix) were obtained for the FF and SSC, respectively. Concerning the ANN, the best results in the test set were achieved for the FF (R2=0.85, RMSEP=1.50 N). The study showed the potential of the HSI technique as a non-destructive tool for measuring apricot quality even along the whole supply chain. [ABSTRACT FROM AUTHOR]

Abstract: In this study we pioneered the use of gas plasma for the treatment of fresh-cut apples and its potential application in the agri-food precesses. Treatments were conducted on fresh-cut Pink Lady® apples using a Dielectric Barrier Discharge (DBD) generator and considering three different times: 10, 20 and 30min. Main quality (soluble solid content, titrable acidy, colour by computer vision system and texture) and metabolic parameters (polyphenol oxidase PPO activity, respiration and heat production) were assessed immediately after the treatment and during a storage of 24h (10°C, 90% RH). In terms of browned areas, a significant decrease was observed in treated samples compared to the control ones (up to about 65% for 30min and after 4h of storage). PPO residual activity decreased linearly by increasing the treatment time (up to about 42%). In general the treatment appeared to slow down the metabolic activity of the tissue. Other qualitative parameters were only slightly affected by the treatment. Industrial relevance: The potential application on in-packed cold plasma technology and its known effect on microbiological decontamination of foods makes this technique very encouraging for fresh-cut fruit stabilization. However very important aspects have to been clarified in order to deeply understand gas plasma effect on fresh-cut apple quality and on the metabolic response of the tissue. [Copyright &y& Elsevier]

Abstract: Empirical and fundamental rheological properties of six food hydrocolloids (carboxymethylcellulose, tara gum, guar gum, locust bean gum, xanthan gum and sodium alginate), as influenced by concentration, were evaluated and correlated. Furthermore, the possibility to estimate the empirical and fundamental parameters by using data coming from a very simple and inexpensive rotational viscometer prototype, was investigated. The prototype was build in laboratory and its simplicity consist of the capability to directly measure a voltage, correlated with the absorbed current, instead of a derived torque and rotation speed measurements of the cylinder probe. Fundamental rheological measurements were performed by using a controlled stress-strain rheometer, while a back extrusion test was performed in order to evaluate the empirical properties. The results reported that all the measured parameters are strongly correlated with the dispersion concentration. The simple prototype was able to predict the empirical parameters with R 2 value from 0.976 to 0.999 by means of exponential, linear, or power law functions and to assess the viscosity from power law or linear functions with R 2 close to 1 for shear rate higher than 50 s −1. [Copyright &y& Elsevier]

Abstract: Non-destructive freshness assessment of shell eggs during 16 days of storage at 20°C was carried out by means of an FT-NIR spectrometer and a fiber optic probe. Diffuse reflectance spectra were acquired in the spectral range 833–2500nm on samples of eggs collected from three different farms, characterized by different rearing methods. After each spectral acquisition, the freshness parameters such as air cell height, thick albumen heights and Haugh unit were destructively measured. For each rearing method, PCA (principal component analysis), PLS (partial least square regression) and PLS-DA (partial least square discriminant analysis), were carried out in order to set up models to predict the freshness parameters and to classify egg samples according to the days of storage. Hierarchical cluster analysis was also conducted to test similarity between values at different days of storage and rearing methods. Predictive models showed R 2 value up to 0.722, 0.789 and 0.676 for air cell height, thick albumen heights and Haugh unit, respectively (test set validations). Egg samples were correctly classified (100%) according to the days of storage. Hierarchical cluster analysis showed a low level of heterogeneity for the three rearing methods within the days of storage. [Copyright &y& Elsevier]

The development of an inexpensive instrumental chain based on time-domain reflectometry is presented. The attention paid to the choice of the components allowed purchase costs reduction compared to the instruments available on commerce. The chain is composed by a hand-made 30-mm needle probe, a square wave fast rise time pulses generator on board, and a digital sampling USB oscilloscope with bandwidth of 11 GHz. Stability measurements and sodium chloride, sucrose, and cow milk were conducted to assess device repeatability and evaluate the predictive potential of estimation for some food parameters. The traditional geometrical-mathematical approach was replaced by multivariate investigation of the time-domain signal. Good results in terms of coefficient of determination up to 0.983 were obtained. The results disclosed show how a cheap and easy-to-use instrumental chain can be very promising for attributes determinations of liquid materials, such as foodstuff. [ABSTRACT FROM AUTHOR]

The aim of the present study was to investigate the main physical and structural properties of honey during static and dynamic induced crystallization. For this aim, three honey samples, chosen with different F/G (fructose/glucose) ratios, were analysed for content of glucose crystals, colour, texture, viscosity and microscopic observations during the two processes. Correlation of data was analysed through Pearson coefficient and Principal Component Analysis. Results showed that the dynamic process allowed to reduce by 5–6 folds the time necessary to reach full crystallization. Moreover, while during static crystallization crystals progressively grew in size, the constant stirring of the mass allowed to obtain products characterized by low hardness and viscosity, due to the formation of micro-crystals. The dynamic process led to final crystallized honeys with very similar colour and structural characteristics although starting from very different initial values. • Honey crystallization occurs 2–5 times faster in dynamic conditions. • Dynamic crystallization significantly affects texture and rheological properties. • Honey crystallized under constant stirring keeps a Newtonian behaviour. • The constant movement of the honey mass leads to very small crystals formation. [ABSTRACT FROM AUTHOR]

This study aims to test the suitability of a waveguide spectrometer, as a rapid and cheap tool to discriminate between different fertilizers according to two different manufacturing methods, such as granulation and blending. The tested instrument is a waveguide vector spectrometer, patented in 2016, that operates in the range 1.6-2.7 GHz, giving both spectral phase and gain measurements. Granulated and blended fertilizers were dehydrated and pulverized to avoid possible interferences due to the water content and the geometry of the sample. The spectral data were analysed by multivariate statistical analysis [principal component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA)] in order to obtain a discrimination tool considering the whole hidden spectral information. PC1 (95% of the explained variance) and PC2 (4% of the explained variance) are shown to explain most of the spectral variability. A tendency to group samples according to the different production methods can be seen, even if the discrimination is influenced by the different chemical compositions of fertilizers. However, PLS-DA models correctly classified 100% of the samples into granulated and blended classes using spectra obtained by waveguide spectroscopy. Despite being preliminary, the tests carried out on a small number of samples show how the technique coupled with PLS-DA models could be able to discriminate between the analysed fertilizers by means of their spectral signature and according to the manufacturing method, if the chemical composition is kept constant. Further tests are necessary to validate the model, also considering the possibility of grouping fertilizers on the basis of their similar composition. [ABSTRACT FROM AUTHOR]

• TD-NMR observed the liquid fraction of honey, where two protons types were identified. • DSC showed that honey dynamic crystallization is 5/6 times faster than the static one. • The crystallization rate of honey did not influence water activity. This work studied water state of honey during crystallization, obtained statically and dynamically, by differential scanning calorimetry (DSC), water activity (a w) assessment and time domain nuclear magnetic resonance (TD-NMR). Crystallization was induced by adding 5% of crystallized honey to three honey samples with different fructose/glucose ratio, the key characteristic for honey crystallization. Samples were stored at 14 °C. Dynamic crystallization was obtained by using an impeller. DSC showed that the dynamic crystallization was faster than the static one, the latter characterized by two phases, showing different rates. The crystallization rate did not affect a w , that remained below 0.600. TD-NMR allowed to separately observe two kinds of protons, both pertaining to liquid sugars, one chemically exchanging with water and one not exchanging with it. The combination of techniques allowed speculating that the two crystallization methods led to crystals of different size and shape. [ABSTRACT FROM AUTHOR]

This preliminary study aimed to compare the application of pulsed electric field (PEF) with a traditional blanching as pre-treatments before frying for the mitigation of acrylamide content in potato crisps. Measuring the degree of cell disintegration index (p o) and the changes in water electrical conductivity during washing of potato slices, PEF protocol and sample preparation scheme were optimized. Peeled potato slices (thickness 1.5 ± 0.2 mm) were subjected to PEF (1.5 kV/cm, pulse duration 10 μs, total treatment time 10 ms, pulse frequency 100 Hz) and to blanching (85 °C for 3.5 min) pre-treatments and then to washing in water, evaluating the reduction of acrylamide precursors (reducing sugars and free asparagine). After frying (175 °C, 3 min), product quality, in terms of colour, texture and acrylamide content were evaluated. Results showed that PEF promoted acrylamide precursors leaching followed by a reduction of the final acrylamide content of around 30%, significantly higher if compared to the reduction obtained with blanching, with only slight modifications of the final quality of the product, in terms of colour and texture. The Commission Regulation (EU) 2017/2158 of 20 November 2017 has introduced new benchmark levels and mitigation strategies for the reduction of the presence of acrylamide in foods, directing food businesses to the research of measures to lower the acrylamide formation in foods. The actual industrial production process of fried potato crisps involves the use of many mitigation strategies, such as a blanching of raw potatoes. However, the traditional blanching treatment presents several practical drawbacks and leads to undesirable changes of the product quality. The application of PEF as a pre-treatment could reduce the acrylamide content in deep-fat fried potato crisps. This preliminary study gives important indications regarding the possibility of combining a PEF pre-treatment on raw potato slices with subsequent industrial processing steps for the production of potato crisps with low acrylamide concentration. • PEF was applied for the reduction of acrylamide content in potato crisps. • PEF pre-treatment was compared to the conventional blanching pre-treatment. • PEF protocol and sample preparation were optimized for industrial application. • The quality of PEF-treated potato crisps (colour and texture) was evaluated. • A reduction of 30% of acrylamide content was achieved after applying PEF. [ABSTRACT FROM AUTHOR]

The increasing demand for high quality and safe food led to important technological innovations in food processing. Cold plasma appears as an emerging technology that has demonstrated efficiency in the removal of microbial contamination from fresh and minimally processed food. In this study, the proteomic profile of Salmonella Enteritidis SE86 subjected to cold plasma treatment was investigated. The number of viable S. Enteritidis SE86 cells was analyzed at different time intervals upon exposure to cold plasma and approximately 100 μg of S. Enteritidis SE86 protein extracts were analyzed by Multidimensional Protein Identification Technology (MudPIT). The results demonstrated that no significant changes in cell counts were detected for up to 20 min exposure to cold plasma, and 2 log reduction was achieved after 60 min. Overall, 1096 proteins were identified, with 249 detected only in plasma-treated samples, and 9 exclusive in non-treated control samples. The proteins uniquely detected in cold plasma-treated cells that showed higher abundance were glyoxalase I, ABC transporter substrate-binding protein and transcriptional activator OsmE, followed by some oxidoreductases. Proteins related with carbohydrate and nucleotide metabolism were mostly overexpressed in cold plasma treated cells, suggesting energy metabolism was increased. [ABSTRACT FROM AUTHOR]

Osmotic dehydration (OD) is a widely used preservation technique that consists in the reduction in food water activity by the immersion of the biological tissue in hypertonic solutions. The aim of this work was to analyze the effect of pulsed electric fields (PEF) in mass transfer as a pre-treatment of the OD using NMR. In this sense, PEF pre-treatments were done using three different voltages (100, 250 and 400 V/cm) and 60 number of pulse. The OD of kiwifruit was carried out in 61.5% of sucrose solution at 25 °C, for a contact period from 0 to 120 min. The water distribution into the cellular tissue was studied by NMR relaxometry. In conclusion, NMR is an excellent technique for quantifying water molecules according to their interactions in the fruit tissue, obtaining the adsorbed water and opening the possibility to apply the BET model to fit the adsorbed isotherm over the whole range of water activity. [ABSTRACT FROM AUTHOR]

The aim of this work was to evaluate the effect of pulsed electric field (PEF) pre-treatment on mass transfer phenomena, water distribution and some physico-chemical parameters of osmo-dehydrated organic strawberries. For PEF treatments 100 near-rectangular shaped pulses, with fixed pulse width of 100 μs and repetition time of 10 ms were used. Electric fields strength applied were 100, 200 and 400 V cm −1 . Afterwards, samples were subjected to OD treatments carried out in two different hypertonic solutions (40% w/w), one with sucrose and the other one with trehalose. The results shown that PEF treatment positively affected the mass transfer during OD even at the lowest electric field strength applied (100 V/cm), partially preserving the cell viability and maintaining at the same time the fresh-like characteristics of strawberries. [ABSTRACT FROM AUTHOR]

The main objective of this study was to evaluate the synergistic effect of atmospheric cold plasma (ACP), Sodium Dodecyl Sulphate (SDS) and lactic acid (LA) on L. monocytogenes and verotoxin-producing E. coli in red chicory. Experimentally inoculated samples were pre-treated with either SDS, or SDS + LA for 5, 10 or 15 min. Pre-treated samples were then submerged in deionized water and either exposed to ACP generated by dielectric barrier discharge device (DBD: fixed parameters: 19.15 V and 3.15 A) for 15 min or left untreated. All combinations of treatments were evaluated for sensory effects. Viable counts of verotoxin-producing E. coli on red chicory decreased by more than 4 logs (4.78 Log CFU/cm 2 vs control) after a treatment with LA + SDS for 5 min and ACP for 15 min and often dropped below the limit of quantification. L. monocytogenes showed a higher tolerance to this sanitizing treatment and the level of inactivation was higher than 3 logs (3.77 Log CFU/cm 2 vs control) only by increasing the duration of the washing step in LA + SDS to 15 min. The different treatments had no detrimental effects on colour, freshness and texture of red chicory, but odour and overall acceptability of the samples treated by ACP slightly decreased during storage. Further optimization of treatment parameters for maintaining fresh characteristics are needed, but the effectiveness of combinations of sanitizers and ACP on other pathogens and fresh produce worth to be investigated. [ABSTRACT FROM AUTHOR]

This work analyzes the effect of Pulsed Electric Fields (PEF) as a pre-treatment of the osmotic dehydration (OD) of kiwifruit ( Actinidia deliciosa cv Hayward ) in the internal structure and in the internal water transport. PEF pre-treatments were done using three PEF intensities (100, 250 and 400 V/cm) and analyzed by TD-NMR. The OD was carried out by immersing the samples in 61.5% sucrose solution at 25 °C. The application of a PEF pre-treatment before the OD produces a process of plasmolysis proportional to the electric field applied. It is because the PEF removes the mobile charges of the medium, such as electrolytes, organic acids, amino acids; Ca + 2 is the major culprit of the plasmolysis because it fixes some of the junctions of the microtubules between the cell wall and the membrane. Therefore, a previous plasmolysis produces an increase in the apoplastic transport increasing the rate of dehydration. Industrial relevance This research describes the effect of the PEF pre-treatment of osmotic dehydration in the microstructure and in the internal water liquid phases transports of the kiwifruit tissue by using TD-NMR. The results of this research have demonstrated that the application of an electric field prior to the osmotic dehydration produces a process of plasmolysis more the greater the electric field applied, due to the elimination of the mobile charges of the medium and mainly affecting the internal transports. Therefore, PEF pre-treatment accelerate the OD treatment preserving the structure and consequently remaining the life cycles, necessaries to obtain a long shelf life of the product. It has been demonstrated the useful of the TD-NMR as a technique able to analyzed the effect of PEF at a microstructural degree. [ABSTRACT FROM AUTHOR]

The simultaneous use of UVA light irradiation coupled with low energy cold plasma generated by a dielectric barrier discharge prototype, results in significant enhancement of efficiency of the integrated process with respect to the sole plasma treatment. This effect has been demonstrated both on microbial inactivation of a food-borne pathogen, i.e. Listeria monocytogenes, and on the degradation of a compound of biological origin such as phenylalanine. In the latter case, the analysis of its reaction intermediates and the spectroscopic identification and quantification of peroxynitrites, allowed to propose mechanistic hypotheses on the nature of the observed synergistic effects. Moreover, it has been demonstrated that the process does not affect the quality of trout fillets, indicating its suitability as a chlorine-free, green, and sustainable tool for the decontamination of fish processing water. [Display omitted] • Cold plasma is a chlorine-free technique for water decontamination and disinfection. • Coupling cold plasma with UVA irradiation leads to process intensification. • Synergy explained by the presence of photoactive species in plasma-activated water. • The treatment does not affect the quality of the food. [ABSTRACT FROM AUTHOR]

[Display omitted] • Experimental results demonstrate an innovative prediction of concrete mechanical resistance using a non-invasive RF system. • A simple predictive model could be implemented with low computational resources in portable devices. • Electromagnetic spectra were acquired on a concrete sample for 29 days. • Spectra and strength values were used as input for the creation of a multivariate statistical model (SIMCA and PLS). • The coefficients obtained by the model allow us to predict compression strength directly from new spectral acquisitions. This paper investigates using microwaves from 1.5 to 14 GHz for monitoring concrete compressive strength in real-time to implement a non-intrusive sensor. The approach is based on acquiring reflected microwave spectra by the concrete irradiated through a rectangular cavity antenna connected to a Vector Network Analyzer (VNA) and investigating their relationship with strength. Since the information is hidden in the spectrum, we used the multivariate statistical analysis technique to create both classification and regression models. The acquired Voltage Standing Wave Ratio (VSWR) spectra were statistically inferred with compressive strength from destructive tests. The experimentation was performed on 16 concrete samples, lasted 28 days, and the acquired data consisted in 409 spectra where the reflected spectra are correlated with the compressive strength during curing time. The inference processes show high predictability, with an F1 score from 0.91 to 0.99 for classification and a cross-validation value of the parameter R2 of 0.997. [ABSTRACT FROM AUTHOR]

The quality of virgin olive oils is assessed through the determination of several analytical parameters, whose values must be within the ranges established by the different institutions involved. In addition to official methods, there is a strong need for simple, rapid, and environmentally friendly techniques for the quality control of virgin olive oils and for addressing the challenging task of determining geographical origin and detecting adulterants. Toward this purpose, some of the most interesting applications based on optical spectroscopic techniques, on the measurement of electrical characteristics and on the use of instruments equipped with electronic chemical sensors, including also other promising techniques are herein discussed. These techniques, adequately coupled with an appropriate statistical approach, appear to be promising for assessment of several quality-related parameters. The prediction of sensory attributes and of the oxidative status of virgin olive oils have also been reviewed by adopting these selected techniques, which are also considered to be potentially appropriate solutions for identification of the geographical origin of virgin olive oils and to assess their adulteration with cheaper oils. Overall, the techniques discussed are promising and cutting-edge approaches for the establishment of useful portable instruments for in situ monitoring of the quality of virgin olive oils. Practical applications: The simple, rapid, and environmentally friendly analytical approaches discussed herein represent promising analytical tools for assuring the authenticity and monitoring the quality of virgin olive oils. Such innovative techniques and tools need to be ring-tested and validated. Some innovative reviewed approaches will permit to develop useful portable instruments able to perform in situ appropriate controls also by small laboratories or olive oil mills with limited technical facilities. These equipments will be potentially usable also by trained 'non-professional analytical skilled' people. Some other approaches, rapid but more expensive, will be applicable mainly by quality control labs and will increase the number of samples analyzed per day, thus fostering laboratory proficiency and an effective fighting against olive oil fraud. Quality analysis of virgin olive oil can be achieved by a set of chemical and sensory determinations. Reference chemical analyses are usually carried out in a laboratory by trained personnel and requires high costs and lengthy times to obtain results. Innovative techniques characterized by high accuracy, short response time, and possibility of in situ analysis to evaluate olive oil quality are reviewed herein. Such techniques can be divided in different groups depending on the principle of the methodology: 1) optical techniques, such as UV-Vis, NIR, MIR, Raman, and fluorescence spectroscopy; 2) electrical techniques, such as electrical impedance spectroscopy, amperometry, and time domain reflectometry; and 3) electronic noses, electronic tongues and other promising approaches, where an array of electrodes or other technical solutions (PTR-MS, FGC E-nose, NMR) are used in conjunction with multivariate data analysis to obtain a chemical fingerprint of the product. [ABSTRACT FROM AUTHOR]