Shelf‐life extension of multi‐vegetables smoothies by high‐pressure processing compared with thermal treatment. Part I: Microbial and enzyme inhibition, antioxidant status, and physical stability

Abstract

Consumer demand for minimally processed food products based on fruits and vegetables is associated with their “fresh‐like” qualities and a desire for convenience. Smoothies could help meet these needs and contribute to increasing fruit and vegetable intake. The first part of this study assesses microbial and enzyme inactivation, antioxidant status, and physical stability of a vegetable smoothie (apple, carrot, zucchini, pumpkin, and leek) stabilized (for up to 28 days at 4°C) by high‐pressure processing (HPP) (350 MPa/5 min/10°C). Compared with mild heating (85°C/7 min), HPP ensured microbial quality (aerobic mesophilic and psychotropic bacteria, yeasts and molds), inhibited peroxidase, and slightly enhanced polyphenol oxidase and pectinmethylesterase enzymes. Consequently, the pressurized smoothies underwent earlier clarification and oxidation as reflected in their values of turbidity, browning index, viscosity, and antioxidant capacity. Therefore, the pressurizing conditions and/or raw material selection need to be improved to achieve better stabilization by HPP.