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.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Fermented beetroot powders have a high content of bioactive components. Fermented beetroot powders have low bacteria amount. Method of spray‐drying fermented juices needs to be refined.
Summary
The ...aim of this study was to evaluate the influence of bacteria type and carrier addition during microencapsulation process by spray‐drying on the microorganism survival and physicochemical properties of fermented beetroot juice powder. Selected bacteria were as follows: L. fermentum, L. plantarum and L. brevis and its mixture in proportion 1:1:1. Fermented beetroot juice containing selected LAB was spray‐dried at 160 °C. Maltodextrin and gum Arabic were used as drying carriers at 10% (w/w). All powders were stable (low water activity below <0.25, high dry matter content 95–98%). Bacteria type had the main influence on the chemical properties and amount of bacteria. The highest bacteria content was observed in powders with L. brevis as a starter, and the same was observed for polyphenols and betalain content. However, the method of drying fermented juices still needs to be refined due to the 50% reduction in the number of microorganisms during the drying process.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The carrot powders quality depends on carrier type and carrier to juice proportion and temperature. Carrot powders have a high content of bioactive components. The most optimal way should focus on ...the most desirable properties of the powders allowing their best use.
Summary
The objective of this study was to determinate the influence of carrier addition and spray drying temperatures (160 or 200°C) on physicochemical properties of spray‐dried carrot juice powder. As carriers, maltodextrin and gum Arabic in different proportions were used. In powders were determined the following: moisture content, water activity, apparent density, size of particles, colour and carotenoids content. The content of carotenoids in powders prepared from solutions with juice to carrier ratio 2:3 was 324.3–406.6 mg/kg d.m., while in powders with a J:C = 3:2 values ranged from 576.7 to 637.7 mg/kg d.m. The highest content of carotenoids and the most yellow colour were observed in powders with 1:3 gum Arabic to maltodextrin ratio. Powders with the highest amount of gum Arabic have the highest diameter and the lowest water activity. High inlet temperature caused brighter colour of powders, higher dry matter content, lower water activity and apparent density of powders.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Several studies have demonstrated the feasibility of pulsed electric fields (PEF) for different applications in food industry. PEF technology is therefore a valuable tool that can improve ...functionality, extractability, and recovery of nutritionally valuable compounds as well as the bioavailability of micronutrients and components in a diverse variety of foods. Additionally, other studies have shown the potential of PEF treatments to reduce food processing contaminants and pesticides. This opens the doors to new PEF applications in the food industry. This review focused on some of the most renowned traditional and emerging PEF applications for improvement of osmotic dehydration, extraction by solvent diffusion, or by pressing, as well as drying and freezing processes. The impact of PEF on different products of biological origin including plant tissues, suspension of cells, by-products and wastes will be analyzed in detail. In addition, recent examples of PEF-assisted biorefinery application will be presented, and finally, the main aspects of PEF-assisted cold pasteurization of liquid foods will also be described.
•PEF potential to develop energy efficient and environmentally friendly processes•PEF is a useful tool to improve extractability, and bioavailability of bioactives.•PEF ability to decrease drying temperature•PEF potential to reduce freezing time•PEF ability to reduce formation of processing contaminants and pesticides
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
► The effect of ultrasonic treatment before drying of apples were investigated. ► The influence of ultrasound treatment on rehydration properties of dried material was studied. ► The changes in ...apples microstructure were examined. ► Ultrasound application caused alteration of rehydration properties. ► Ultrasound treatment and subsequently drying induced changes of apple microstructure.
The aim of this work was to investigate the utilization of ultrasound as a mass transfer enhancing method prior to drying of apples tissue. Ultrasound power was provided at a frequency of 35kHz for 10, 20 and 30min in the ultrasound bath. Apple cubes were dried using convection method in 70°C and at air velocity of 1.5m/s. The effects of ultrasound pre-treatment upon drying were investigated.
The ultrasound treatment caused reduction of the drying time by 31% in comparison to untreated tissue. The ultrasound treated apples exhibited between 9% and 11% higher shrinkage, 6–20% lower density, and porosity of 9–14% higher than untreated samples. Considerable differences in the density and porosity of the dried apple with and without ultrasonic application were confirmed by scanning electron microscopy image analysis of the investigated tissue. Moreover, ultrasound application caused alteration of rehydration properties in comparison to untreated sample.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
In the present study, the thermal properties (drying time, effective moisture diffusion (Deff), specific energy consumption (SEC)), and quality (color and shrinkage) of kiwi slices were optimized ...using the response surface methodology (RSM). The optimization process was done using central composite design (CCD) in Design Expert software with three independent variables including microwave power (100, 200, and 300 W), sample thickness (4, 6, and 8 mm), and ultrasound pretreatment time (10, 20, and 30 min). The results showed that by increasing the microwave power and ultrasound pretreatment time and decreasing the thickness, the SEC, and drying time decreased in quadratic form, while the Deff linearly increased. Moreover, decreasing microwave power and sample thickness as well as increasing the treatment time diminished the shrinkage and color. The obtained optimal results (4 mm thickness, ultrasound for 30 min, 257.2 W of microwave power) were: drying time for 13.779 min, Deff equal 6.67 × 10−9 m2/s, SEC equal 6.343 MJ/kg, the total color difference of 17.94, and shrinkage of 46%.
Novelty impact statement
Numerous studies have addressed the drying of food products using ultrasound pre‐treatment. However, the optimization process is required for different methods of drying, parameters of treatment as well as type of the material. Thus, the response surface methodology (RSM) was applied for optimization and modeling the drying process and chosen physical properties of ultrasound‐treated kiwifruits slices prior to microwave drying.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
•Ultrasound was applied to different thawing state followed by enzymatic treatment.•The highest quality of juices was obtained when ultrasound was applied up to 50 °C.•Usually longer the ultrasound ...thawing, higher the bioactive components contents were.•Ultrasound to 50 °C and enzymatic treatment increased the extraction efficiency.•Ultrasound applied before juice extraction may replace the costly enzymatic treatment.
Ultrasound (US) assisted thawing of blue honeysuckle berry was utilized in order to reduce the losses of bioactive components (ascorbic acid, anthocyanins, phenolic acids, iridoids, proanthocyanins) and increase the extraction efficiency during juice processing. It was analysed whether it was more beneficial to apply US (alone or with enzymatic treatment) to the frozen state, until reaching the cryoscopic temperature or thawed state. Both the US and enzymatic treatment significantly increased the extraction efficiency, extract content, acidity and the content of iridoids and chlorogenic acid in juices, especially if the US was applied to 50 °C. It was probably due to a higher extractivity by the greater damage of the tissue and detexturation. Enzymatic treatment due to long heating contributed to a higher degradation of anthocyanins, ascorbic acid and proanthocyanidins, which are more heat-sensitive. The results of the study mainly indicated the possibility of including ultrasound-assisted thawing in the fruit processing before pressing the juices. This may replace costly enzymatic treatment.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The influence of low-temperature spray drying (inlet/outlet air, 75/50 °C) with the use of dehumidified air on rapeseed honey phenolics, antioxidant activity, and aroma compounds was investigated. ...Maltodextrin and NUTRIOSE® were used as carriers. Additionally, skimmed milk was tested as water substitute for feed solution preparation. Honey powders obtained by this method were characterized by high antioxidant activity and rich aroma. Changes in aroma profile during drying at low temperature were recognized as favorable and creating desirable fragrance of the product. In the case of 80% honey powders (20% of carrier), the investigated properties were not deteriorated comparing to pure honey before drying. Thus, this level of carrier addition can be treated as optimal from the point of view of bioactive properties retention during low-temperature spray drying. Such low carrier addition was not presented before in case of honey spray drying, and is favorable due to the perception of such product as natural. If used as food component, the dose of such honey-rich powder can be reduced comparing to traditional products containing higher amount of carrier (usually not lower than 50%).
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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.
•Application of combined PEF and US intensifies drying process.•PEF followed by US resulted in better carotenoids retention than US followed by PEF.•Rehydration of carrots treated by PEF and US was comparable to untreated samples.•Electrical conductivity was correlated with drying time and hygroscopicity.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The drying process preserves the surplus of perishable food. However, to obtain a good-quality final product, different pretreatments are conducted before drying. Thus, the aim of the study was the ...evaluation of the effect of thermal (blanching treatments with hot water) and non-thermal technologies (pulsed electric field (PEF) and ultrasound (US)) on the kinetics of the drying process of red bell pepper. The convective and microwave-convective drying were compared based on quality parameters, such as physical (water activity, porosity, rehydration rate, and color) and chemical properties (total phenolic content, total carotenoids content, antioxidant activity, and total sugars content). The results showed that all of the investigated methods reduced drying time. However, the most effective was blanching, followed by PEF and US treatment, regardless of the drying technique. Non-thermal methods allowed for better preservation of bioactive compounds, such as vitamin C in the range of 8.2% to 22.5% or total carotenoid content in the range of 0.4% to 48%, in comparison to untreated dried material. Moreover, PEF-treated red bell peppers exhibited superior antioxidant activity (higher of about 15.2-30.8%) when compared to untreated dried samples, whereas sonication decreased the free radical scavenging potential by ca. 10%. In most cases, the pretreatment influenced the physical properties, such as porosity, color, or rehydration properties. Samples subjected to PEF and US treatment and dried by using a microwave-assisted method exhibited a significantly higher porosity of 2-4 folds in comparison to untreated material; this result was also confirmed by visual inspection of microtomography scans. Among tested methods, blanched samples had the most similar optical properties to untreated materials; however non-thermally treated bell peppers exhibited the highest saturation of the color.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
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