Storage stability of vitamin C fortified purple mashed potatoes processed with microwave-assisted thermal sterilization system

Abstract

Quality changes in ready-to-eat, shelf-stable foods, during storage can be influenced by many factors, such as processing, storage conditions, and the barrier properties of the packaging. This research investigated retention of vitamin C and anthocyanin in purple mashed potatoes as influenced by packaging barrier properties and encapsulation during storage after microwave assisted thermal sterilization. Purple mashed potatoes fortified with encapsulated (EVC) or non-encapsulated vitamin C (NVC) were packaged in two high-barrier polymer pouches (TLMO and PAA), processed with a pilot-scale microwave assisted thermal sterilization (MATS) system ( F ₀ = 10.7 min), and stored at 37.8 °C for 7 months. MATS processing caused a significant increase ( P < 0.05) in the oxygen transmission rates (OTRs) of PAA pouches but did not affect the barrier properties of TLMO pouches. PAA film also had a significantly higher ( P < 0.05) water vapor transmission rate (WVTRs) than TLMO films, which resulted in a significantly higher ( P < 0.05) weight loss in the samples packaged in PAA pouches than TLMO pouches. Purple mashed potatoes containing encapsulated vitamin C in both TLMO and PAA pouches showed the highest retention over 2 months of storage at 37.8 °C than non-encapsulated vitamin C. Additionally, purple mashed potatoes exposed to 700 lumens light showed a significantly higher ( P < 0.05) deterioration in the anthocyanin, total phenolic content, color, and vitamin C. Overall, MATS processed purple mashed potatoes in high barrier polymeric packaging can minimize the quality changes when stored in dark conditions during storage and have an extended shelf life.

Keywords

flexible packaging / shelf life / thermal processing / antioxidant / encapsulation