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Fresh basil and parsley leaves are perishable and they are often processed by drying, which is an energy-consuming process and contributes to nutrient degradation. These downsides can, however, be mitigated by various pre-drying treatments. Thus, the objective of this study was to assess the impact of different treatments (ultrasound, steaming, dipping) and their duration (20, 30 min) on contents of chlorophylls and lutein (analyzed by UPLC-PDA), total phenolic content (TPC), as well as antioxidant capacity (determined as DPPH radical scavenging activity) in basil and parsley leaves. The changes in the chemical properties after treatments were more significant in the case of basil than parsley, probably due to a lower thickness of leaf epidermis layer and stiffness of the former. In comparison to fresh leaves, enhanced extractability of chlorophyll a after all treatments and TPC after dipping for 20 min, was observed in basil. In parsley, instead, the chlorophylls content remained unchanged after treatments, but TPC decreased. Lutein content remained stable in both herbs following different treatments. Irrespectively of the treatment type, the TPC and antioxidant capacity were higher after 20 min of basil treatments, while in the case of parsley, higher TPC was determined after longer treatments (30 min). The study demonstrated that the investigated treatments could preserve or even enhance the chemical properties of herbs.

In recent years, an increasing interest in reducing sugar consumption has been observed and many studies are conducted on the use of polyols in the osmotic dehydration process to obtain candied or dried fruits. The studies in the literature have focused on the kinetics of the process as well as the basic physical properties. In the scientific literature, there is a lack of investigation of the influence of such polyol solutions such as sorbitol and mannitol used as osmotic substances during the osmotic dehydration process on the contents of bioactive components, including natural colourants. Thus, the aim of the study was to evaluate the impact of polyols (mannitol and sorbitol) in different concentrations on the process kinetics and on chosen physical (colour and structural changes) as well as chemical (sugars and polyol content, total anthocyanin content, total polyphenol content, vitamin C, antioxidant activity) properties of osmotic-dehydrated organic strawberries. Generally, the results showed that the best solution for osmotic dehydration is 30% or 40% sorbitol solutions, while mannitol solution is not recommended due to difficulties with preparing a high-concentration solution and its crystallization in the tissue. In the case of sorbitol, the changes of bioactive compounds, as well as colour change, were similar to the sucrose solution. However, the profile of the sugar changed significantly, in which sucrose, glucose, and fructose were reduced in organic strawberries and were partially replaced by polyols.

The conditions of convective drying induce a negative effect on the quality of the dried products, and thus, innovative solutions, such as the utilization of ultrasound and dehumidified air are gaining importance. Therefore, the aim of this study was to evaluate the impact of ultrasound pretreatment and variable air temperature on the kinetics of convective drying with dehumidified air and the quality of dried apples. Apples were dried with dehumidified and non-dehumidified air at 55, 70 and 85 °C. Preliminary ultrasound treatment was conducted by immersion for 60 min. The effect of both ultrasound and dehumidified air utilization was more prominent in the terms of drying time reduction, when lower drying temperatures were used. Drying of apples with dehumidified air, preceded by ultrasound pretreatment, resulted in a greater rehydration capacity of the products, and limited the browning process. Dehumidified air increased the lightness of the dried products, while sonication darkened them. The use of ultrasound before drying coupled with a drying with dehumidified medium at a temperature of 70 °C reduced the exposure of the product to a high temperature and oxygen. Products treated before dehumidified air drying with ultrasounds were characterized by high total phenolic content and the greatest antioxidant activity. This was because such technological treatment reduced exposure of the product to a high temperature and oxygen.

The aim of this work was to compare selected physicochemical properties of air dried ‘Golden Delicious’ apples, pretreated either by high-pressure processing (HPP), ultrasound (US) or pulsed electric field (PEF). Following parameters of pretreatment were used: HPP–400 MPa for 15 min, US–21 kHz, 180 W for 45 min, PEF–1 kV/cm, 3.5 kJ/kg. The quality of materials was evaluated by their rehydration properties, hygroscopicity, color and total phenolic content. To compare the effectiveness of the utilized methods, determined properties were expressed as relative comparison values against the reference sample obtained without any pretreatment in the same conditions. The performed research demonstrated that properties can be shaped by the application of proper pretreatment methods. For instance, PEF was shown to be the best method for improving water uptake during rehydration, whereas HPP was the most effective in decreasing hygroscopic properties in comparison with untreated dried apples. Among the investigated methods, HPP resulted in the deepest browning and thus total color difference, while the effects of US and PEF were comparable. For all pretreated dried apples, the total phenolic content was lower when compared with reference material, though the smallest drop was found in sonicated samples.

In the study, the impact of combined pulsed electric field (PEF) and ultrasound (US) pre-treatments on drying kinetics and quality of dried carrot was evaluated. Carrot samples were subjected either to US followed by PEF (US-PEF) treatment or to PEF followed by US (PEF-US) treatment. Afterwards material was dried using convective method at 70 °C. Drying time of the samples subjected to combined treatment ranged from 180 to 255 min, whereas in the case of untreated carrots the drying time was equal to 298 min. The highest water diffusion coefficient (11.5·10−10 m2/s) was calculated for the samples subjected to PEF treatment followed by immersive sonication and it was 63% higher than reference ones. No significant differences were stated when comparing the rehydration properties of all investigated samples. However, samples pre-treated by combined method exhibited lower ability to adsorb water vapour from environment. Subjecting carrots to combined treatments resulted in a better carotenoids retention (60.5–80.6%). The material treated by PEF-US or US-PEF exhibited higher values of redness (a*) and lower of yellowness (b*) in comparison to untreated dried carrots.

In recent years, traditional high-temperature food processing is continuously being replaced by nonthermal processes. Nonthermal processes have a positive effect on food quality, including color and maintaining natural food pigments. Thus, this article describes the influence of nonthermal, new, and traditional treatments on natural food pigments and color changes in plant materials. Characteristics of natural pigments, such as anthocyanins, betalains, carotenoids, chlorophylls, and so forth available in the plant tissue, are shortly presented. Also, the characteristics and mechanism of nonthermal processes such as pulsed electric field, ultrasound, high hydrostatic pressure, pulsed light, cold plasma, supercritical fluid extraction, and lactic acid fermentation are described. Furthermore, the disadvantages of these processes are mentioned. Each treatment is evaluated in terms of its effects on all types of natural food pigments, and the possible applications are discussed. Analysis of the latest literature showed that the use of nonthermal technologies resulted in better preservation of pigments contained in the plant tissue and improved yield of extraction. However, it is important to select the appropriate processing parameters and to optimize this process in relation to a specific type of raw material.

This chapter presents the mechanism of the enhancement of freezing by means of ultrasound (US). It has been demonstrated that the effects of US are a rather complex issue. In theory, ultrasound creates cavitation bubbles throughout the volume of the product, which promotes nucleation of the ice and crushes the crystals already present in food. They can also enhance convective heat transfer to the cooling media, thereby accelerating freezing. Moreover, it has been shown that ultrasound reduces the degree of supercooling before nucleation in frozen food. Additionally, numerous experimental studies indicate that ultrasound assisted freezing is a good method to achieve homogenous crystallizations, reduce the deteriorating effect of freezing on food, and thus improve quality after thawing.

Ultrasound is one of the most often investigated nonconventional technologies applied to enhance drying progress. The existing literature proves that ultrasound can be used to accelerate the process, reducing drying time and decreasing energy consumption. Shorter exposure to elevated temperature during water removal provides a better quality of product, expressed as both physical and chemical properties. Moreover, ultrasound treatment itself can participate in the modification of some quality parameters, due to the mechanisms that it provokes during pretreatment. On the other hand, the complexity of the phenomena and processes that can be induced in the food matrix by sonication is one of the biggest challenges for food scientists and engineers. Based on the results presented and discussed in this chapter, it seems that ultrasound application, when it aims towards drying improvement, requires optimization not only for each individual raw material but also for each specific process. This situation can be considered as a drawback and benefit alike since it opens multiple ways of ultrasound utilization for water removal enhancement.

In this chapter the mechanism of the enhancement of freezing by the means of pulsed electric field (PEF), the use of cryoprotectants alone or with PEF during vacuum impregnation (VI) or osmotic dehydration (OD) were described. Both the freezing kinetics and the quality aspects were discussed and compared with other nonthermal technologies, such as ultrasound, high hydrostatic pressure, or radio-frequency treatment. The results showed that the PEF treatment due to electroporation of cell membranes improved the freezing kinetics, but the degree of the freezing time reduction was dependent on the food matrix. On the other hand, food texture after PEF is usually softened and the color can be changed. These negative aspects of PEF treatment may be minimized by the use of cryoprotectants during VI or OD in combination with PEF that helps in implementation of cryoprotectants into the cells. These treatments are promising due to obtaining a product with enhanced, more fresh-like texture and maintained turgor after thawing and have already been commercialized for green leafy vegetables.

Both ultrasound (US) and pulsed electric field treatment (PEF) allow achieving similar technological aims. Their application can for instance improve food preservation or enhance heat and mass transfer based processes. However, the mechanisms of action and the impact of these technologies on the structure of biological systems are different. Based on the knowledge concerning the behaviour of tissue subjected to pulsed electric field or sonication it can be assumed that the combination of these techniques can be beneficial. Therefore the aim of this study was to analyse the impact of pulsed electric field, ultrasound and combined (pulsed electric field followed by ultrasound or ultrasound followed by pulsed electric field) treatment on electrical conductivity, intercellular structure, mechanical and acoustic properties of plant tissue as exemplified by carrot samples. Performed research proved that the mechanism of action and the consequences of US treatment are different in comparison to pulsed electric field application. The efficiency of sonication cannot be evaluated on the basis of electrical conductivity like it is usually done in the case of electroporation efficacy assessment. The results concerning mechanical and acoustic properties also indicate that pulsed electric field causes higher alterations of intercellular structure than ultrasound. In general the utilization of US prior to PEF treatment can enhance the effectiveness of electroporation.

Food safety is a crucial aspect, when designing food packaging. It is necessary to assess every layer of the material that could be interacting with food. There are various substances that could be used to produce coatings for the cardboard materials, safe for the application in the food packaging materials. By introducing additional layer to the packaging material, it is possible to enhance food safety, improve packaging and food quality, and extend food shelf-life. The aim of this work is to present the background of some applications of paper coatings based on proteins, polysaccharides, lipids and others. Moreover the food safety aspect of paper and cardboard was described.

The aim of this study was to investigate the effects of pre-treatment in ethanol solution carried out in variable time with and without ultrasound (US) assistance on convective drying kinetics, total phenolic content (TPC) and hygroscopicity of an apple. The drying time after immersion in ethanol solution was shorter up to 13.4 (without US) and 18.3 % (with US) in comparison to intact slices. The most appropriate model that described kinetics of drying was the one proposed by Sledz et al. Drying of the untreated apple resulted in a decrease of the TPC by 18 %, compared with raw apples and the pre-treatment led to further losses. The tissue after ethanol pre-treatment was less hygroscopic, which proves the possibility to maintain a characteristic texture of the dried apple with prolonged storage stability. The best quality of dried apples was obtained after 1 min of ethanolic pre-treatment with US.

The aim of this study was to investigate the effect of a pretreatment, performed by a combined method based on blanching, ultrasound, and vacuum application, on the kinetics of osmotic dehydration and selected quality properties such as water activity, color, and bioactive compound (polyphenols, flavonoids, and anthocyanins) content. The pretreatment was carried out using blanching, reduced pressure, and ultrasound (20 min, 21 kHz) in various combinations: Blanching at reduced pressure treatment conducted three times for 10 min in osmotic solution, blanching with reduced pressure for 10 min and sonicated for 20 min in osmotic solution, and blanching with 20 min of sonication and 10 min of reduced pressure. The osmotic dehydration was performed in different solutions (61.5% sucrose and 30% sucrose with the addition of 0.1% of steviol glycosides) to ensure the acceptable taste of the final product. The changes caused by the pretreatment affected the osmotic dehydration process by improving the efficiency of the process. The use of combined pretreatment led to an increase of dry matter from 9.3% to 28.4%, and soluble solids content from 21.2% to 41.5%, lightness around 17.3% to 56.9%, as well as to the reduction of bioactive compounds concentration until even 39.2% in comparison to the blanched sample not subjected to combined treatment. The osmotic dehydration caused further changes in all investigated properties.

Ultrasound (US) is a promising technology, which can be used to improve the efficacy of the processes in food technology and the quality of final product. US technique is used, e.g., to support mass and heat transfer processes, such as osmotic dehydration, drying and freezing, as well as extraction, crystallization, emulsification, filtration, etc. Osmotic dehydration (OD) is a well-known process applied in food processing; however, improvements are required due to the long duration of the process. Therefore, many recent studies focus on the development of OD combined with sonication as a pretreatment method and support during the OD process. The article describes the mechanism of the OD process as well as those of US and changes in microstructure caused by sonication. Furthermore, it focuses on current applications of US in fruits and vegetables OD processes, comparison of ultrasound-assisted osmotic dehydration to sonication treatment and synergic effect of US and other innovative technics/treatments in OD (such as innovative osmotic solutions, blanching, pulsed electric field, reduced pressure and edible coatings). Additionally, the physical and functional properties of tissue subjected to ultrasound pretreatment before OD as well as ultrasound-assisted osmotic dehydration are described.

The purpose of this study was to investigate the effect of pre-treatment in ethyl alcohol for 5, 15, 60 and 180 s with the application of ultrasound on the course of convective drying and properties of carrot tissue directly after the treatment and after the drying process. The treatment in ethanol resulted in loss of mass, increase of dry matter, ethanol conductivity, extractivity of carotenoids with a slight effect on the colour of carrot tissue after the treatment. The utilization of ultrasound during immersion in ethanol contributed to additional increase of conductivity of ethanol, and extractivity of carotenoids. The immersion in ethanol virtually did not affect the drying kinetics, which can be explained by the increase of shrinkage of the tissue in relation to the untreated dried tissue. Despite the lack of the influence on the drying course in the ethanol-immersed carrot, an increase of the carotenoid content (up to 135%) and the rehydration ability (up to 19%) was noted with the simultaneously unchanged colour of dried carrot in comparison to untreated dried material, which indicates the possibility to improve the quality of dried carrot after immersion in ethanol.

The aim of this work was to analyse the acoustic and mechanical properties of pulsed electric field treated solid-like plant tissue as exemplified by apple fruits. The electrical conductivity of the untreated and PEF treated samples was measured as well. Additionally, an attempt to use the acoustic emission as a tool to assess the electroporation efficiency was done. Subjecting the apple discs to PEF treatment resulted in altered mechanical, electrical and acoustic properties. The compressive force registered at 15% strain was reduced by the PEF application up to 72.7% in comparison to the intact material. The number of acoustic events obtained by the contact method was the most suitable acoustic emission descriptor among other ones to differentiate the PEF treated and intact materials. The results of experiment and especially the PCA point out that the acoustic emission measured by the contact method can be a useful tool to evaluate both the disintegration efficiency and texture changes caused by the PEF application.

The aim of this study was to analyze the impact of traditional and combined pretreatment on dehydration kinetics and quality of dried swamp cranberries. Fruits were blanched, cut, or treated by combined technique consisting of blanching and application of pulsed electric field. Afterwards, fruits were subjected for osmotic dehydration (OD; 72 hr) in 61.5% sucrose solution or in ternary solution consisting of 30% sucrose with 0.1% addition of steviol glycosides to ensure similar sweetness of both mixtures. In the case of samples treated by combined method, OD was enhanced during first 30 min by sonication. Partially dehydrated cranberries were air dried at 70 °C. The quality of dehydrated fruits was assessed by the means of phenolics content, anthocyanin content, flavonoid content, vitamin C content, water activity, and color. Blanching decreased drying time by 48% to 50% in comparison to cutting. Utilization of combined method reduced drying time of cranberries up to 55% in comparison to cut samples. Water activity of all samples was below 0.6. Blanched samples or blanched and then treated with pulsed electric field and ultrasound contained more anthocyanins and flavonoids and less sucrose than cut samples. PRACTICAL APPLICATION: According to current trends in food and beverage industry, consumers seek for products which does not contain excessive amounts of sugars, salt, or fats. Dried cranberry fruits are rich in bioactive compounds and need to be osmotically dehydrated in sugar solutions to make the taste of the final product acceptable. Osmotic dehydration is also carried out to decrease time of drying, which is one of the most energy intensive processes. Therefore, there is a need to develop a technology with potential to maintain the bioactive compounds, reduce sugar content in comparison to traditionally process fruits, and enhance the kinetics of drying.

The aim of the study was to investigate the impact of pulsed electric field (PEF) treatment on the convective drying kinetics of a carrot and color and microstructure changes of the dried product. Samples were treated by PEF with the specific energy input equal to 5.63, 8 and 80 kJ · kg−1. After PEF treatment, thermal conductivity and electrical conductivity were measured. Drying time of the PEF-treated samples was reduced up to 8.2% (Ws = 8 kJ · kg−1, 5 kV · cm−1; 10 pulses) in comparison to intact tissue. Statistical analysis showed that Midilli et al.’s model was considered to describe the kinetics of the process the most precisely. Pulsed electric field treatment increased the effective water diffusion coefficient up to 16.7%. Moreover, PEF treatment and drying caused the alteration of the sample color. After drying, the lightness and chroma were higher or unchanged in comparison to the intact tissue. The dried PEF-treated samples exhibited significantly higher redness (higher value of a* para...

The aim of the study was to investigate the influence of ultrasound treatment applied in osmotic solution on bioactive compounds, such as vitamin C, polyphenols, anthocyanins and flavonoids content as well as antioxidant activity in cranberries (Vaccinium oxycoccus). Ultrasound treatment was performed at the frequency of 21 kHz for 30 and 60 min in two osmotic solutions - 61.5% sucrose and 30% sucrose with an addition of 0.1% of steviol glycosides. Before the ultrasound treatment the material was subjected to cutting or blanching. The obtained results indicated that the influence of ultrasound waves on cranberries depends on a type of bioactive component. The ultrasound treated cranberries as well as the ones subjected to cutting or blanching enhanced by ultrasound were characterized mainly by a lower content of bioactive compounds.

Parsley leaves contain a high amount of bioactive components (especially lutein), therefore it is crucial to select the most appropriate pre-treatment and drying conditions, in order to obtain high quality of dried leaves, which was the aim of this study. The optimization was done using response surface methodology (RSM) for the following factors: microwave power (100, 200, 300W), air temperature (20, 30, 40°C) and pre-treatment variant (ultrasound, steaming and dipping as a control). Total phenolic content (TPC), antioxidant activity, chlorophyll and lutein contents (using UPLC-PDA) were determined in dried leaves. The analysed responses were dependent on the applied drying parameters and the pre-treatment type. The possibility of ultrasound and steam treatment application was proven and the optimal processing conditions were selected.

The aim of the study was to investigate the effect of ultrasound treatment in osmotic solution, carried out at different time and solutions, on mechanical and thermal properties of cranberries. Ultrasound treatment was applied for 30 and 60 min in liquid mediums such as 61.5 % sucrose solution and 30 % sucrose solution with 0.1 % steviol glycosides addition. Before the ultrasound treatment samples were subjected to traditional operations (cutting, blanching). The traditional operations and ultrasonic treatment of whole fruits did not influence or slightly influenced dry matter content and mechanical properties. The cutting had impact on thermal properties to the highest extent due to the exposition of fruits’ flesh. The combination of cutting and sonication decreased thermal conductivity which suggests that mass transfer was more pronounced. The sonication had greater influence when compared to only ultrasonic treatment. Combined both cutting and blanching with ultrasonic treatment led to greater changes in cranberries properties.

The benefits of using hybrid drying are increasingly remarked. Microwave-convective drying (MW-CD) links the advantages of both microwave and convective drying methods and allows the negative phenomena that appear when the methods are used separately to diminish. Most importantly, reduced specific energy consumption and relatively short drying time are observed, which can be additionally decreased by the application of various preliminary treatments, e.g., pulsed electric field (PEF). Thus, the purpose of this study was to determine the impact of PEF pretreatment on the MW-CD of apples and its chosen physicochemical properties. This research was designed using response surface methodology (RSM). The first variable was microwave power (100, 200, and 300 W), and the second was specific energy input (1, 3.5, and 6 kJ/kg). Optimization responses were assumed: drying time to MR = 0.02, water activity, hygroscopicity after 72 h, rehydration ratio, relative dry matter content, total phenolic content, ability to scavenge ABTS•+ radical cations, and DPPH• radicals based on the EC50 values. The most optimal parameters were comprised of specific energy intake of 3.437 kJ/kg and microwave power of 300 W (desirability equalled 0.624), which provided the most minimized drying time and obtaining of apples with the most desired properties.