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Abstract The evaluation of the impact of food processing on the nutrients and health benefits of vegetables and fruits is of high practical importance. In this short literature overview the refractance window drying (RWD) technology, a novel contact drying technique, was compared with other drying techniques as the freeze drying technique to stabilize fruits and vegetables. The antioxidant capacity, phenolic or polyphenol content and carotenoids are important published quality properties. The RWD technology as mild drying process showed various opportunities to maintain the product quality and the nutrient content as well as their biological activity to a high degree. Highlights • Refractance window drying (RWD) technology is a mild drying process. • Air-drying, freeze drying and RWD retained almost the same antioxidant capacity in leek samples. • The antioxidant capacity of RW dried fruit is significantly higher than in spray-dried samples. • The energy efficiency of the RW dryer is 3-fold and 40-fold higher compared to the spray dryer and the freeze dryer, respectively. • The content of carotenoids and capsaicinoids decreases significantly by freeze drying and oven drying as well as RW drying. [ABSTRACT FROM AUTHOR]

Highlights: [•] The antioxidant capacity and the total content of phenolic compounds in the white shaft of leek was stable during 13 days of refrigerated storage. [•] The total phenolic content in the white shaft of leek was stable during 13 days of refrigerated storage. [•] A significant increase in the concentration of isoalliin could be observed during refrigerated storage. [•] The ACSO content in the white shaft of packaged leek was significant lower than the content in the white part of the entire leek. [Copyright &y& Elsevier]

Abstract: Extracts of the white shaft and green leaves of 30 leek cultivars were investigated for their antioxidant properties, total phenolic (TP) and l-ascorbic acid (AA) content. The measured antioxidant properties included free radical scavenging activities against peroxyl (ORAC) and 2,2-diphenyl-1-picrylhydrazyl radicals (DPPH) and their Fe3+ reducing capacity (FRAP). The results from this study suggest that the green leek leaves generally have significantly stronger antioxidant properties than the white shaft. Correlation analysis between the TP and the AA content and the antioxidant activity showed that phenolics and ascorbic acid contribute significantly to the antioxidant activity of leek. The three antioxidant activity assays were all correlated for the extracts of the white shaft of the 30 leek cultivars. Principal component analysis (PCA) elucidated the influence of part and type of cultivar on the antioxidant capacity, TP, and l-ascorbic acid content, whilst the breeding strategy and seed company had no influence. [Copyright &y& Elsevier]

The impact of low-oxygen spiral-filter press technology combined with thermal pasteurization (TP), pulsed electric field (PEF) and high pressure processing (HPP) on cloudy apple juice quality was investigated immediately after the treatments and after 3 weeks of storage at 4 °C. Based on equivalent levels of microbial safety and desired shelf-life, low and high processing intensities were selected: TP (72 °C/15 s; 85 °C/30 s), PEF (12.5 kV/cm, 76.4 kJ/L; 12.3 kV/cm, 132.5 kJ/L), and HPP (400 MPa/3 min; 600 MPa/3 min). High intensity thermal treatment resulted in a bright, yellowish color which was maintained during storage. PPO and POD activities were largely reduced by high intensity PEF and TP yet showed high resistance to HPP. The highest vitamin C content was provided by fresh juice followed by PEF-treated juices. Due to oxidative degradation reactions, vitamin C of all treated samples significantly decreased during storage. Immediately after processing, high cloud stability values were obtained in all samples; however, cloud stability decreased during storage particularly for HPP juices with high residual PME. No significant changes were observed in pH, titratable acidity, organic acid and sugar content which also corresponded to sweet and sour taste. Results from untargeted volatile profiles showed that esters increased after PEF and were better retained after HPP. Contrary to TP treatment where ester degradation reactions occurred together with the formation of off-flavors. Most of the volatiles decreased during storage which could be linked to oxidation and ester hydrolysis reactions. Being one of the most popular fruit juices consumed worldwide, cloudy apple juice can still undergo quality changes such as color degradation, cloud loss (fast sedimentation) and flavor changes during processing and storage. This study evaluates the potential of low-oxygen spiral-filter press in combination with different preservation technologies to obtain a maximal quality of cloudy apple juice. Results showed that high intensity thermal pasteurization can effectively inactivate quality-degrading enzymes, therefore it is useful to obtain an optimal cloudy apple juice product in terms of color and cloud stability. Although HPP has minimal impact on aroma of the juice, shelf-life of the juice may be limited due to incomplete enzyme inactivation. In the case of PEF treatment, thermal effects may contribute to maintain apple juice quality. • Enzymes can be completely inactivated by high intensity thermal processing. • Less effect of processing and storage on particle sizes, acidity and sugar content • Spiral-filter press combined with PEF or HPP retained the fresh apple juice aroma. • Spiral-filter press coupled with severe pasteurization preserved color and cloud stability. • Thermal effects resulting from PEF may contribute in maintaining the juice quality. [ABSTRACT FROM AUTHOR]

Industrial processing of fruit and vegetables can have detrimental effects on health-promoting phytochemicals. Here, a novel pilot-scale process using an innovative spiral-filter press followed by a thermal treatment was evaluated for the production of tomato juice. Three-month storage of the resulting juice was also evaluated. The process impact of the different unit processes, with emphasis on the novel spiral-filter pressing, was investigated for the three major compound classes present in tomato (ascorbic acid, phenolic compounds and carotenoids). The spiral-filter press processing did not seem to cause degradation of ascorbic acid, phenolic compounds or carotenoids, which can be ascribed to the fast processing in a low-oxygen atmosphere. Maintaining the native constitution of tomato to a great extent, the spiral-filter press thus offers potential for processing tomatoes and other vegetables into juices, smoothies and purees. [ABSTRACT FROM AUTHOR]

• Apple pomace extracts obtained using DES solvents exhibit antioxidant properties. • Apple pomace extracts using classical solvent systems promote insulin secretion. • Specific DES systems resulted in extracts with insulinotropi effects. The objective of this study was to examine the bioactivity of extracts from apple pomace obtained by non-conventional green extraction methods (DES systems). Bioactivity was antioxidant capacity and ability to stimulate insulin secretion from pancreatic beta-cells. The antioxidant capacity of extracts was examined using the DPPH and the FRAP assay. Impact of the extracts on cell viability and insulin secretion were examined using the BRIN-BD11 cell line. ChCl:EG(1:4) extracts resulted in high antioxidant capacity in the DPPH assay (80.1% inhibition versus 11.3%). Extracts obtained from the classical systems demonstrated an ability to promote insulin secretion significantly higher than the positive control, p < 0.05. ChCl:EG(1:4) extracts stimulated insulin secretion to a lesser extent. Overall, the data provides evidence for the potential of DES systems to extract bioactive compounds from apple pomace that have relevance for metabolic health. Further optimisation of the extraction procedures should be tailored to the desired bioactive properties. [ABSTRACT FROM AUTHOR]

This study focused on investigating quality changes of thermally processed kale purée using an integrated targeted and untargeted approach. Low, medium, and high processing intensities (carried out at 70, 90, and 128 °C) were selected based on predetermined shelf-life targets: frozen-thawed, refrigerated, and ambient storage, respectively. The results show that that physicochemical properties determining consumer acceptability were largely dependent on the treatment intensity. The high intensity treatment resulted in the least favorable quality characteristics (distinct brown color, chlorophyll a nd vitamin C destruction as well as a phase separation after storage). Enzymes were inactivated with increasing thermal load. Regarding taste related compounds, there was no clear effect of processing and storage on acidity and sugar profiles. The untargeted GC–MS approach showed that increasing the processing intensity resulted in an increase of the formation of furans and sulfides. Storage clearly affected the formation of volatiles that could be, depending on the thermal treatment, attributed to lipid and/or carotenoid oxidation, continuation of Maillard reactions, and enzyme catalyzed reactions. Compared to other Brassicaceae vegetables such as as broccoli, cauliflower and different types of cabbages, kale so far has received little attention from an industrial processing point of view. However, kale has been reported to contain high nutritional value due to its important content of minerals, bioactive compounds and fibre. With the growing health awareness of consumers and increasingly busy lifestyles, the demand for more convenient fruit and vegetable products with high nutritional content has increased. Therefore, research to obtain more insight on the effect of processing and storage on kale purée is important. • A combined targeted and untargeted approach is useful to study quality changes during processing and storage • High-intensity thermal processing had the least favorable quality characteristics • Low-intensity processing resulted in quality changes due to enzymatic reactions • Enzymes can be inactivated by medium- and high-intensity thermal processing • No significant impact of processing and storage on acidity and sugar content [ABSTRACT FROM AUTHOR]