High pressure processing and heat sterilization of kale: Impact on extractability, antioxidant capacity and storability of carotenoids and vitamin E

Abstract

AbstractFood process engineering represents a rapidly evolving discipline traditionally focussing on thermal treatments including objectives such as preservation and stabilization. Innovative and gentle preservation techniques such as high‐pressure processing (HPP) may potentially improve or replace conventional methods by enhancing nutritional and health aspects, flavor and taste, sustainability, and more consumer‐targeted, minimally processed food items. As information about the impact of HPP (600 MPa, 5–40 min) on lipophilic food ingredients (e.g., carotenoids, vitamin E) in kale is limited, a comparison to heat sterilization (20 min, 121°C) may result in new insights related to lipophilic, antioxidant capacity (L‐AOC), extractability and storage stability (8 weeks, 5°C). HPP of chopped kale resulted in significantly increased (p < 0.05) total carotenoid and chlorophyll contents in contrast to declined concentrations of vitamin E. Significantly decreased extractabilities were observed for total carotenoids and chlorophylls in heat sterilized kale, showing no significant change (p > 0.05) in vitamin E content. Moreover, 2 months of storage of HP‐treated kale resulted in a major loss of vitamin E and total carotenoid contents compared to thermally treated samples. Elevated α‐tocopherol equivalent antioxidant capacities (αTEAC) and lipophilic oxygen radical antioxidant capacities (L‐ORAC) correlated with an increased pressure holding time.