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The objective was to review, using an integrated approach, all parameters related to osmotic dehydration, freezing, and frozen storage when assessing the advantages of the osmodehydrofreezing-ODF process. Peeled cherry tomatoes were treated at (T) 25, 35, and 45 °C (t) up to 180 min in glycerol-based OD-solution (50, 60, 70% w / w ). OD was studied and optimized by applying the Response Surface Methodology, combined with selected desirability criteria to define the optimum process parameters. Water loss-WL, solid gain-SG, water activity reduction-a w , texture and color changes were monitored during the process. Untreated and OD-treated at optimal OD conditions (C = 61.5%, T = 36 °C; t = 72 min) samples were frozen and stored at isothermal (T, -5, -8, -14, -23 °C) and non-isothermal temperature conditions (T eff , -7.3 °C). OD samples presented acceptable color, increased firmness, low drip loss and high vitamin C/lycopene retention during frozen storage. OD increased the shelf life of frozen cherry tomato (up to 3.5 times based on sensory quality loss). The kinetic models obtained for vitamin and lycopene degradation and sensory quality loss were validated at non-isothermal conditions.

This study focused on the osmotic dehydration (OD) of ready-to-eat spinach leaves combined with the pulsed electric field (PEF) pre-treatment. Untreated and PEF-treated (0.6 kV/cm, 0-200 pulses) spinach leaves were osmotically dehydrated at room temperature for up to 120 min. The application of PEF (0.6 kV/20 pulses) prior to OD (60% glycerol, 25 °C, 60 min) lowered water activity ( a w = 0.891) while achieving satisfactory product acceptability (total sensory hedonic scoring of 8). During the storage of the product (at 4, 8, 12, and 20 °C for up to 30 d), a significant reduction in total microbial count evolution was observed (9.7 logCFU /g for the untreated samples vs. 5.1 logCFU /g for the PEF-OD-treated samples after 13 d of storage at 4 °C). The selection of these PEF and OD treatment conditions enabled the extension of the product shelf life by up to 33 d under chilled storage. Osmotically treated spinach could find application in ready-to-eat salad products with an extended shelf life, which is currently not possible due to the high perishability of the specific plant tissue.

An objective of the present study was the enrichment of skim sheep yoghurt milk base with hydrolysates (WPHs) of whey protein concentrate (WP80) derived from Feta cheesemaking. Moreover, the use of high hydrostatic pressure (HP) treatment at 600 MPa/55 C/10 min as an alternative for heat treatment of milk bases, was studied. In brief, lyophilized trypsin and protamex hydrolysates of WP80 produced under laboratory conditions were added in skim sheep milk. The composition and heat treatment conditions were set after the assessment of the heat stability of various mixtures; trisodium citrate was used as a chelating agent, when needed. According to the results, the conditions of heat treatment were more important for the physical properties of the gel than the type of enrichment. High pressure treatment resulted in inferior gel properties, irrespective of the type of enrichment. Supplementation of skim sheep milk with whey protein hydrolysates at >0.5% had a detrimental effect on gel properties. Finally, skim sheep milk base inoculated with fresh traditional yoghurt, resulted in yoghurt-type gels with high counts of Lb. delbrueckii subsp. bulgaricus and Str. thermophilus -close to the ideal 1:1- and with a high ACE inhibitory activity >65% that were not essentially affected by the experimental factors., Competing Interests: The authors declare no conflict of interest.