Search

Sous-vide treatment is a modern minimal processing cooking technique that uses a single-step temperature of 55–70 °C and longer time. The quality attributes of meat might be improved by including cooking steps at below 50 °C temperatures in the sous-vide treatment. The aim of this study was to investigate the effects of the double-step sous-vide treatments on the quality attributes of the chicken breast and comparing with the traditional single-step sous-vide treatments. The single-step sous-vide treatments were performed at 60 °C. In the double-step sous-vide treatments the first step temperature was 45 °C and the end temperature was 60 °C. Double-step sous-vide treated chicken breasts obtained higher tenderness, moisture content and lower weight loss compared to the single-step sous-vide treated chicken breasts. Double-step sous-vide treatment provided an attractive cooking method to produce high quality chicken breast, however, challenge tests for specific pathogens would be useful for the assessment of the microbiological quality for different treatment combinations.

The effect of high pressure processing (300 and 600 MPa) combined with mild heat treatment (55 and 75 °C) on the colour parameters, anthocyanin content, and sensory characteristics of strawberry puree were examined after the treatments and 2 weeks of cold storage at 2 and 15 °C. As on an industrial scale the simultaneous implementation of these treatments remains a challenge, the HHP and heat treatments were carried out consecutively in different sequences. The colour parameters and the anthocyanin content did not change significantly due to the treatments, but decreased during cold storage, at 15 °C storage the changes were more intensive than at 2 °C. Regarding the sensory test results, the different sequence of the 600 MPa-75 °C combined treatments is not detectable even after 2 weeks of storage at 15 °C, but in case of 300 MPa-55 °C, the enzyme inactivation is probably not sufficient enough as differences between the samples were detected.

This work aimed to study the antimicrobial activity of eight various components of plant origin on the growth of Pseudomonas lundensis and Listeria monocytogenes. Different in vitro methods were used: agar plate diffusion, micro atmosphere, agar hole diffusion, micro-dilution, and gradient-plate method. In the first agar plate assay, p-cymene and γ-terpinene did not inhibit the growth of the tested bacteria therefore they were not used in further experiments. Both α-pinene and limonene were only partially effective, but these were screened only for their partial inhibition. The other four components completely inhibited the growth of the tested bacteria. Using the agar-well diffusion method showed that carvacrol and thymol were found to be the most effective active components, thymol had minimum inhibitory concentration (MIC) at 1.563 mg/mL, however, in the case of carvacrol, MIC was 7.813 μL/mL. Additionally, eugenol and camphor show the same results but in higher concentrations. Gradient plate method was used to determine MIC values, in which it has been proved that carvacrol and thymol possess strong antimicrobial activity, no growth of tested bacteria was observed with carvacrol (100 μL/mL), while thymol exhibited MIC of 1.887 mg/mL against P. lundensis and 0.943 mg/mL needed to show complete inhibition of Listeria monocytogenes. Further experiments are needed to determine the optimum concentrations of the active components against P. lundensis and L. monocytogenes.

Sweeteners of natural sources, such as sugar alcohols, are in the centre of growing interest. Their impact on the phytochemicals, antioxidant and sensory properties of blackberry jams were investigated during a 9-months storage period. Measurements on jams prepared with different sugars and sugar alcohols (sucrose, fructose, xylitol and erythritol) were performed at the date of preparation and in the 1st, 3rd, 6th, 9th month.Total polyphenol content, individual polyphenols, antioxidant properties, anthocyanin content and CIE L*a*b* colour were determined. Sensory profiles were determined by a trained panel. Sensory attributes were compared by the results of the electronic tongue and nose.Sweeteners had a significant impact on physicochemical properties and sensory attributes. Storage time also affected the sensory and compositional properties of jams. Changes in antioxidant properties did not follow a clear trend during the storage period, and antioxidant capacity was not affected significantly by the sweetening agent, but showed a significant decline from the 6th month. A positive effect of xylitol was observed in terms of a low degradation rate of anthocyanins, while their decomposition was the fastest in the fructose-containing preparation. Jams sweetened with erythritol reached significantly lower values for some sensory attributes (blackberry flavour and general taste intensity), however, they showed more intense red colour. Multiple factor analysis enabled the identification of the effect of sweetener and storage time on the pattern of the sensory data matrix. Classification according to individual sweeteners was performed successfully by the electronic tongue, but not by electronic nose.

This study was conducted to evaluate the effect of bioactive compounds (BACs): linalool (LIN) and piperine (PIP) on chicken meat characteristics. The meat was treated with 500, 1000 ppm of BACs, vacuum packaged and stored at 4 °C for 8 days. Physicochemical characteristics, lipid oxidation (thiobarbituric acid reactive substances, TBARS), microbiological status, and sensorial (electronic-nose based) properties were investigated. Both BACs significantly increased the redness (a*) and chroma (C*) values in meat compared to increased lightness (L*) and higher TBARS in control. Although both BACs showed overlapping aroma profile, the E-nose was able to distinguish between the different meat groups. LIN with various dilution ratios, particularly 1:10 (v:v), showed in vitro growth inhibition against Escherichia coli, Staphylococcus aureus, Salmonella Typhimurium, and Bacillus cereus, concomitantly Listeria monocytogenes required 1:80 (v:v) to be inhibited, and no inhibition was detected for Pseudomonas lundensis. In contrast, PIP at different dilutions did not exhibit inhibitory activity. Regarding aerobic mesophilic counts (AMC), less than 7 log CFU g⁻¹ were recorded except for control showing higher log. Both BACs have potential to improve quality characteristics and increase the shelf life of meat and meat products.

Due to its biological composition, poultry meat is perishable by nature and susceptible to quality deterioration such as microbial spoilage and oxidation changes. Meat and meat products with healthy, extended shelf-life and good organoleptic properties are highly demanded by consumers. In current study, the antimicrobial and antioxidant effects of allyl-isothiocyanate (AITC) as a natural additive on raw chicken meat during chilling storage were determined. For this purpose, samples of minced were treated with different concentrations of AITC (100, 200, 300 and 500 ppm) and control no AITC added, the samples packaged and stored for 8 days at 4 °C. Fluctuations with no significant effect were noticed in TBARS values during the storage period. Simultaneously, AITC with higher concentration showed lower mesophilic aerobic counts compared to control and meat containing a low concentration of AITC. Moreover, compared to the beginning of storage, AITC decreased water holding capacity (WHC) of meat this can affect other physicochemical properties of meat. Further study needed to determine the effect of AITC on the physicochemical properties of meat and food products.

Peroxidase (POD) was extracted from Prunus domestica and partially purified by three methods: ammonium sulfate precipitation, hydrophobic interaction chromatography, and ion exchange chromatography, respectively. The selected procedure allowed a 26.33-fold purification, and the molecular mass estimated by SDS-PAGE was 58 kDa. The purified enzyme presented enzymatic activity toward guaiacol, pyrogallol, catechol, and showed no activity toward ferulic, caffeic, and p-coumaric acids. In terms of optimum parameters for activity, the pH was 6.5, whereas the temperature was 25°C. The enzyme exhibited high stability in the pH range of 5.0–7.0 and in the temperature range of 25–70°C. The most potent inhibitors of POD were L-cysteine and sodium metabisulfite. The thermal inactivation displayed a first-order kinetic model, with an activation energy of Ea 84.79 ± 2.2 kJ/mol. POD extracted from plums exhibited high stability at high-pressure treatment, maintaining over 50% of the initial activity even at 700 MPa.

In this study, polyphenol oxidase (PPO) was extracted from Prunus domestica and partially purified by ammonium sulfate precipitation, hydrophobic interaction chromatography, and ion exchange chromatography. The final purification step revealed a 32.81-fold purification, and the molecular mass was estimated to be 65 kDa by SDS-PAGE. The purified PPO showed enzymatic activity mainly toward five substrates, namely catechol, catechin, 4-methyl catechol, chlorogenic acid, and L-3,4-dihydroxyphenylalanine, whereas it showed no activity toward caffeic acid, ferulic acid, p-coumaric acid, p-cresol, and l -tyrosine. The optimum pH and temperature values were 6.0 and 25 °C, respectively. The enzyme showed high stability in the pH range of 5.0–7.0 and in the temperature range of 25–65 °C. The most effective inhibitors of this enzyme were found to be ascorbic acid and l -cysteine. The thermal inactivation followed a first-order kinetic model, with activation energy of Ea 150.46 ± 1.29 kJ/mol. PPO extracted from plum showed stability at high pressure, with enzyme activation at 500 MPa.

High hydrostatic pressure (HHP) technology, as a promising alternative of thermal-treatment and chemical preservatives, can be used to produce minimally processed foods. It has the advantage of affecting only non-covalent bonds of macromolecules in foods, and thus preserves nutritional components, taste, and flavour exceptionally well. However, HHP also influences enzymatic reactions of food. Although some of these changes are often beneficial, monitoring the potential effects of high pressure treatments — especially in the field of product and technology development — is essential. The aim of this study was to point out some parameters of high hydrostatic pressure technique (pressure, temperature, build-up time, holding time, number of cycles) that can substantially impact the sensory properties of treated products.

Pre-cut tomato and carrot were irradiated with doses of 1.0, 1.5 and 2 kGy. Unirradiated control and irradiated samples were compared organoleptically by a sensory panel. Microbiological analyses were performed directly after irradiation and during post-irradiation storage for 8 days at 5 °C. Ascorbic acid contents, composition of carotenoids and tocopherols were determined. Statistically significant differences of sensory scores between unirradiated and irradiated samples were observed only in the texture of sliced carrots. Total aerobic viable cell counts have been reduced by about two log cycles with 1.5 kGy dose. Total coliforms and moulds were below the detection limit of 15 CFU/g in the irradiated samples during the refrigerated storage. Yeasts were relatively resistant part of the microbiota of pre-cut tomatoes, but 2 kGy dose reduced them below the detection limit. In pre-cut tomatoes, alpha-tocopherol and some carotenoids seemed to be the most radio-sensitive losing approximately one-third of their original concentrations at the dose of 2 kGy. At this dose tocopherols and the level of ascorbic acid decreased also one-third of the initial level in sliced carrots. Additional experiments were conducted to study the effect of irradiation and storage on the population of Listeria monocytogenes and Listeria innocua artificially inoculated on cut tomato and carrot. Cell numbers of both test organisms decreased by at least two log-cycles as an effect of 1 kGy dose. Our studies confirmed earlier findings on a temporary antilisterial effect of freshly cut carrot tissue. No re-growth of Listeria was observed during the studied storage period. The results of these studies suggest that irradiation with 1 kGy gamma rays could improve sufficiently the microbiological safety of the investigated pre-cut produce to satisfy the requirement of low microbial raw diets with acceptable nutritional quality and without diminishing significantly the organoleptic parameters of the commodities.

There is an increasing consumer demand for fresh, shelf stable and healthy products with the favourable sensory properties of the original material food. In the beverage industry the appearance of Alicyclobacillus acidoterrestris spp. presents a problem which has to be solved. In this study the effectiveness of combined high hydrostatic pressure and heat treatment was investigated to examine its microbiological reducing ability regarding the A. acidoterrestris DSMZ 2498 in commercial pasteurized apple- and orange juice. In addition it was studied whether the electronic nose is able to show the differences during the 4 weeks storage time regarding the decreasing number of microorganisms which is in connection with aroma changes. It was established that the combined heat- and high pressure treatment caused microbial inactivation of acidoterrestris at different levels dependent on the combination of applied treatment parameters. These differences could be followed also by the electronic nose.

In our tests, we artificially infected liquid whole egg samples with Salmonella enteritidis, Listeria monocytogenes, and Staphylococcus aureus bacteria, and then treated the samples in “Food Lab900” high hydrostatic pressure (HHP) instrument for 3–17 min at 200–400 MPa. Subsequently, the change of the viable cell count of the specific bacteria has been tested. In addition to the samples infected with various bacteria, non-infected samples were also treated in each test and the change in viable cell count, colour and viscosity of the samples upon the effect of the treatment. In summary, it can be concluded that in each test of our investigations, the viable cell count of S. enteritidis critical for egg products is reduced significantly, while the reduction of the total viable cell count was around two magnitudes. Additionally, based on our results, microbial destruction, reduction of enthalpy (denaturation of egg white) caused by the treatment at HPP, and colour change are primarily affected by the pressur...

The consumers have increasing desire towards fresh, long shelf-life and healthy products by consisting favourable sensory properties. As an ambivalent fact appears that the product should meet all these requirements and should be consumable long time. All these demands lead to the importance of the minimal processing methods. The properties of widely common citrus juices (100% orange, – grapefruit, – and tangerine juice) were analyzed by measuring the possible changes in the physical–chemical parameters (pH, Brix°, electric conductivity, colour) respectively the aroma and acid content. The applied technology was pulsed electric field (in furthers: PEF) treatment with the parameters of 28 kV/cm with 50 pulses; respectively high hydrostatic pressure (HHP) technology with the parameter of 600 MPa pressure for 10 min treatment time. The sensory properties of the juices were analyzed with electronic-nose and -tongue to measure the possible changes of the treated juices compared to the untreated (control) samples with the help of these electronic tools, which can serve as a potential detection system for the differentiation of the treatments mentioned above. Industrial relevance Fruit juices are preserved mainly by heat treatment which can change many prosperous flavour- , acid and sensory properties. The present work shows in case of citrus juices the application of pulsed electric field treatment and high hydrostatic pressure techniques as non-thermal preservation possibilities and the use of electronic tongue and – nose as a new method for sensory testing.

The effect of preservatives on microbial quality, pH, drip-loss, roasting-loss, colour, and sensorial properties of modified atmosphere packaged (70% O 2 and 30% CO 2 ) minced beef ( M. semimembranosus ) stored at (2 ± 0.5 °C) for 12 days was investigated. Beef cubes (approx. 20 × 20 × 20 mm size) were immersed in solutions of 2% and 5% lactic acid, 2% lactic acid combined with 0.5% sodium ascorbate, 20% potassium lactate and 20% potassium sorbate before mincing. Addition of lactic acid was associated with pH drop, which increased drip-loss and roasting-loss. Application of all additives inhibited aerobic micro-organisms (10 3 –10 4 CFU g −1 on day 12) compared to reference sample (9 × 10 5 CFU g −1 on day 12). Lactic acid discoloured samples, while sodium ascorbate seemed to improve colour stability. Despite good visual colour characteristics, potassium sorbate treated samples were organoleptically unacceptable with massive off-flavour.

Experimental batches of chilled boneless slices of pork meat have been stored aerobically in sterile Petri dishes and total aerobic plate counts (TAPC) and sensorial observations were made periodically during storage to monitor bacterial growth and apparent deteriorative changes at 4, 8 and 12 °C, respectively. Near infrared spectroscopy (diffuse reflectance) measurement was performed on replicate meat samples in the wavelength range of 1000–1800 nm. Second derivative and multiplicative scatter correction were performed on the spectra as data pre-treatments. Principal component analysis (PCA) and canonical discriminant analysis (CDA) were used for observation of discrimination of the samples due to loss of freshness and onset of bacterial spoilage as a function of the storage time. The percentage of correctly classified samples decreased somewhat by increasing the storage temperature. Partial least squares (PLS) chemometric model was developed to predict and quantify bacterial loads from the scatter corre...

High hydrostatic pressure (HHP) processing technology offers the possibility to preserve quality attributes. Objective test methods describing quality in a complex form have an important role in the development of new products and in the quality assurance of different technologies. Therefore, research was performed to compare the effects of HHP treatment and heat pasteurization on visual appearance, volatile composition, taste and texture properties of strawberry purees measured by sensorial and objective methods. Sensory evaluation did not show significant differences between samples. Similar result was obtained from the color measurements. Viscosity of purees changed only slightly as a result of the treatments. Electronic nose and electronic tongue were found to be promising tools for discrimination of strawberry purees treated by different levels of high hydrostatic pressure or thermal treatment. Canonical discriminant analysis showed that control and “600 MPa for 5 minutes” samples were quite similar. Samples treated by 600 MPa for 15 minutes were distinguished from the above mentioned ones. The heat treated samples (80°C for 5 and 15 minutes) were definitely separated from the control samples. Fusion of the data from the electronic nose and tongue showed the same trend and improved the classification of the treated puree samples.

Experiments were performed to study the effects of high hydrostatic pressure (HHP) and gamma irradiation, respectively, from two aspects. The effects of HHP treatments on minced pork meat exposed to 50–800 MPa for 20 min and stored at 4 °C for a period of 1 week were examined. The immediate effects of HHP on egg white samples were compared to that of irradiation. Egg white samples were subjected to irradiation (3 kGy) and HHP treatment (400 MPa, 5 min) and measured immediately after treatments. The recorded electronic nose data and near infrared spectra were evaluated using different methods of multivariate qualitative analyses.

Experiments were performed to study changes caused by irradiation or high hydrostatic pressure pasteurization of liquid egg white by differential scanning calorimetry, spectrofluorimetry, electronic nose measurements and NIR-spectrometry. The non-thermal pasteurization treatments were also assessed in relation to loss of carotenoid content, and lipid- and cholesterol oxidation of liquid egg yolk. Unlike radiation pasteurization, high pressure processing caused protein denaturation in egg white, which manifested in changes of its DSC-thermogram and intrinsic tryptophan fluorescence. Electronic nose testing showed changes of the head-space volatile composition of egg albumen, particularly as a function of radiation treatment. Both treatments caused changes in the NIR-spectrometric “fingerprint” of the liquid egg white. Various chemometric analyses of the results of the latter instrumental methods, particularly statistical techniques developed by the group of one of the co-authors of this article, demonstrat...

Polyphenol oxidase (PPO) was isolated from strawberries (Fragaria ananassa) and some of its biochemical characteristics were studied. The optimum pH for strawberry PPO activity was pH= 5.0. K m and V max values were 5.95 mM and 133.8 A 420nm /min using a 50 mM catechol substrate solution. Kinetic studies showed that the thermal inactivation of strawberry PPO followed biphasic kinetics, resulting in an activation energy of 314.1 kJ/molfor the labile fraction and 321.3 kJ/mol for the stable fraction. Pressure/ temperature inactivation of the stable fraction of strawberry PPO can be adequately described by a first-order model. Pressure and temperature were found to act synergistically, except in the high temperature-low pressure region where an antagonistic effect was observed. A second-degree polynomial model was successfully applied to describe the temperature/pressure dependence of the inactivation rate constants of the stable strawberry PPO fraction.

In principle, high hydrostatic pressure (HHP) processing offers the possibility to preserve berry products while affecting their volatile components less than heat pasteurization. Therefore, we performed preliminary investigations to compare effects of HHP treatment (600 MPa, 5 min, at ambient temperature) and heat pasteurization (80 °C, 5 min) on volatile composition of raspberry, strawberry and blackcurrant purees measured by ‘electronic nose’ at 25 °C. Changes in the head space volatiles could be monitored by this method. Taking into account the confusion matrix of the discriminant analysis, heat-treatment had a more significant effect on volatile compounds than HHP. So, application of HHP treatment can retain volatiles of berry products.

hereisanincreasingconsumer� demandforhighquality,� minimally- processed,� additive-freeand� microbiologically-safefoods.�The� applicationofnon-thermalfoodprocessing� techniques,�suchasultra-highhydrostatic� pressureandgammairradiation,� inde- velopingrapidly.�Beingnon-thermaltreat- ments,� foodcomponentsinvolvedinboth� sensoryandnutritionalqualityremainlarge- lyunaffected.�Inordertogainexperience� onthefeasibilityofnon-thermalpasteurisa- tionofegg,�theeffectsofultra-highhydro - staticpressure�(uHP)� andgammairradia- tiontreatmentswereinvestigatedonfresh� samplesofliquideggwhite.� Nearinfrared� (NIR)� spectroscopywasusedinorderto� monitorqualitychangescausedbytheap- pliedtreatmentsascomparedtountreated� controlsamples.�ourreportsdescribingthe� treatmentsandotheranalyticaltechniques� havebeenpublishedelsewhereingreater� FluidPowerLtd,� uK)� andgammairradia- tion�(3�kGydose)�(RH-γ-30,� Moscau),�re- spectively.�Thesampleswereanalysedim- mediatelyafterthesetreatmentsbyaNIR� spectrometerinordertoseethedifferences� intheNIRpropertiescausedbythevarious� procedures.�NIRspectrawererecordedon� aMetriNIR�10-17�PRtypeNIRspectrometer� inthewavelengthrangeof�1000-1700�nm� withaspectralstepof�2� nm. Forevaluation,�thefirststepinvolvedap- plicationofthePolarQualificationSystem� (PQS) 3 � usingautomaticwavelengthrange� optimisation.� Subsequently,� aSampleRec- ognitionTool�(SRT)� wasalsousedtodis- criminatebetweenthesamplesandtopro- ducetheclassification�(confusion)� matrices.� ResultsofPQSandSRTanalysiswerethen� comparedwiththeclassicalmathemati- cal-statisticalmethodsofprincipalcom- ponentanalysis�(PCA),� canonicaldiscrimi- nantanalysis�(CDA)� andtheircombination� (PCA�+�CDA),� calculatingthediscriminant� functionsusingthefirstfewprincipalcom- ponents. ThePQSwasintroducedatthe�3 rd �Inter- nationalConferenceonNearInfraredSpec- troscopyinBrussels.�AccordingtoPQS,�a� "qualitypoint"� wasdefinedonatwo-dimen- sional�"qualityplane"� anda�"polardistance"� wasusedtodescribequalitydifferences.� Thequalitypointoftheinvestigatedmaterial� wasgivenonthequalityplanebythecentre� ofitsspectrumrepresentedinapolarco- ordinatesystem. 4