High hydrostatic pressure treatment and storage of soy-smoothies: Colour, bioactive compounds and antioxidant capacity

• Changes are evaluated in colour and functional properties in HPP-soymilk smoothies.
• HPP-soy smoothies preserve colour better than untreated and heat-treated smoothies.
• Ascorbic acid, carotenoids, polyphenols and antioxidant activity is effectively retained after HPP.
• HPP extends the shelf life of soy smoothies to 45 days.

Bioactive compounds: lycopene, α-, β- and ε-carotenes, ascorbic acid, chlorogenic, p-coumaric, caffeic, hesperidin, narirutin, genistein, daidzin, daidzein, catechin and epicatechin were quantified in order to provide new information on high pressure (HP) processing (550 and 650 MPa/3 min/20 °C) compared to pasteurization (80 °C/3 min) in a multifruit-soymilk smoothie. Antioxidant activity (FRAP and DPPH), colour differences and storage effects (45 days/4 °C) were also investigated. HP maintained better original colour (ΔE< 2.82) than pasteurization (ΔE = 3.70), and did not modify the content of bioactive components (α- and ε-carotenes, ascorbic acid, total polyphenols); it even increased the concentration of lycopene and β-carotene and had higher antioxidant capacity than in heat-treated samples. Most remained quite stable under cold storage. About 55% of the ascorbic acid, the main compound relating to antioxidant capacity (r = 0.7399 for FRAP and r = 0.8944 for DPPH), was retained at the end of the storage period.