High hydrostatic pressure treatments for keeping quality of orange vegetables smoothies

© 2018 International Society for Horticultural Science. All rights reserved. In order to avoid sensory and nutritional quality losses, novel approaches as alternatives to thermal pasteurization have been proposed, such as high hydrostatic pressure processing (HPP). The physicochemical (pH, titratable acidity, soluble solids content and color), microbial quality, phenylalanine ammonia lyase activity and total phenolic content (TPC) changes of an orange smoothie (carrot and pumpkin) after different HPP treatments (0 (CTRL), 300, 400, 500, 600 MPa for 5 min at 23°C) and after 7 days at 5°C were studied. In general, quality parameters did not greatly change after HPP treatments compared to CTRL samples on the processing day and after 7 days at 5°C. HPP reduced initial mesophilic counts (3.4 log CFU mL-1) by 2.0-2.7 log units, without differences among HPP treatments, these microbial counts being well maintained after 7 days at 5°C while CTRL samples increased by 4.1 log units. Generally, the initial PAL activity (206.4 µM kg-1 h-1 of cinnamic acid) was greatly reduced after HPP treatments and throughout storage although the 300 and 600 MPa HPP achieved the greatest enzyme activities after 7 days. The initial TPC (712.1 mg chlorogenic acid equivalent kg fw-1) was reduced by 31, 14 and 7% after 300, 400 and 500/600 MPa treatments, respectively, although it increased up to 1.6-fold after storage. A TPC increment throughout storage was observed for all samples, those smoothies treated at 300 and 400 MPa registering the highest TPC levels after 7 days. Conclusively, all HPP treatments greatly kept the microbial and physicochemical quality of the smoothie after 7 days at 5°C although treatments at 300 and 400 MPa achieved the highest TPC.