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Undersized kiwifruits are considered waste, therefore, there is a need to develop sustainable processing technologies for their valorization, in order to have a positive economic impact on their entire production chain. Therefore, the aim of this study was to apply pulsed electric fields (PEF) combined with osmotic dehydration (OD) and air drying (AD) to develop a novel yellow kiwifruit dried snack with high nutritional functionality. In particular, the effect of the different pre-treatments, PEF (200 V/cm) and/or OD (trehalose at 40%), on the color, bioactive compounds content and antioxidant activity (AA) was evaluated on kiwifruit chips air-dried at three different temperatures (50, 60, 70 &deg, C). The results showed that better color maintenance was observed at the drying temperature of 60 &deg, C. Concerning the bioactive compounds, a good retention in total polyphenols (TP), vitamin C content and AA with the DPPH method was obtained on OD and PEF kiwifruit dried snacks, similar to that of control samples. Instead, the ABTS method showed the best AA in PEF and OD/PEF samples. In general, a shorter drying time in the OD- and PEF-treated samples could contribute to the higher sustainability of the process.

This work aimed to determine the effect of homogenization pressures (HPH) and addition of trehalose on the functional and technological properties of low pulp mandarin juice (LPJ). A set of experiments was designed, combining a non-targeted metabolomic 1 H NMR based approach together with suspended pulp and transmittance, hesperidin, vitamin C and antioxidant activity analysis. Suspended pulp increased with HPH and trehalose addition. Flavonoid hesperidin initially decreased with HPH but trehalose addition resulted in less flavonoid degradation during storage, increasing the effect with the HPH. Vitamin C was not affected by trehalose and pressure treatment but more Vitamin C degradation was observed in trehalose samples during storage. Antiradical activity improvement by trehalose was conditioned by homogenization pressures and specific bioactive compounds. 1 H NMR based approach highlighted the HPH effect on the microbiological aspects of low pulp mandarin juice by the identification of key molecules responsible of the microorganism profile evolution during storage.

Vacuum impregnation combined with other techniques such as air drying allows obtaining not only a low-moisture product but also to enrich it with beneficial bioactive compounds. The aim of this work was to evaluate the efficacy of combined process that involves vacuum impregnation and air drying to obtain an enriched strawberry snack. The strawberry samples were vacuum impregnated with bilberry juice-based solution at three different sucrose concentrations: 10, 30 and 50 °Brix. Afterwards, the samples were subjected to air-drying treatment at 40 °C for 24 h and the obtained final products were analysed for texture, colour, total polyphenol content (TPC), antioxidant activity and sensory analysis. Moreover, the volumetric impregnation level was evaluated, and the drying kinetics were studied. The impregnated and dried samples showed higher values of TPC and antioxidant activity than those of control ones, due to the high antioxidant power of the bioactive compounds present in bilberry juice. The sample that showed the highest value of total polyphenol content and antioxidant activity was the one impregnated with bilberry juice at 30 °Brix. The impregnated and dried samples presented lower firmness and crispness in comparison to the control; however, all analysed samples were above the acceptability threshold by sensory analysis.

The aim of this work was to evaluate the efficacy of an innovative edible coating, based on chitosan from mushrooms enriched with procyanidins extracted from grape seeds, on fresh blueberry quality maintenance, (weight loss, pH, dry matter, colour, firmness and antioxidant activity) and microbial growth, during 14 days of storage at 4 °C. For weight loss, pH and dry matter no relevant differences were detected among the control and the differently coated samples at each considered storage time. Chitosan and chitosan + procyanidins coatings promoted a slight decrease of luminosity and an increase of blue hue colour of blueberry samples during the whole storage period. The use of coating promoted an increase in the antiradical activity that was the highest in blueberries coated with chitosan + procyanidins. Microbiological analysis results indicated that the chitosan-based coated samples had a significantly higher yeast and mould growth inhibition compared to the uncoated sample.

The aim of this work was to quantify the recovery of juice and bioactive compounds of apple and carrot mashes treated by the electrotechnologies (PEF or OH) at different pre-heating temperatures (40, 60 or 80 °C), considering thermal and electric field based cell disintegration. In general, a higher cell disintegration resulting from the applied pre-treatments also resulted in higher juice yield (around 10% increase for carrot and 5% for apple compared to untreated). Regarding the carotenoid content of obtained carrot juices, only the PEF pre-treatment at 20 °C resulted in an increased extractability. A release of total polyphenols from apples into the juice increased in all pre-treated samples compared to the control. This study suggests that a combined pre-treatment can further improve the cell disintegration and juice yield and may have the potential to increase the recovery of bioactive compounds depending on the treatment parameters. Industrial relevance Thermal treatment followed by PEF or conducted by OH can still improve the cell disintegration and yield of juice. Moreover, the combination of thermal and electric field effects may also improve the recovery of bioactive compounds depending on the chosen treatment conditions. Therefore, the combined treatments show high potentiality for the application at industrial level to improve the release of the juice and at the same time to obtain novel products with high quality.