Effect of vacuum grinding and storage under oxygen free condition on antioxidant activity and bacterial communities of strawberry puree

Abstract

The purpose of this study is to investigate the effects of vacuum processing on antioxidant activity and microbial growth of strawberry puree over day 10 after storage at 5, 25, and 35 °C. The strawberry puree was prepared under vacuum (7.2 Pa) using a specially designed grinding and packaging system. Grinding under vacuum resulted in significantly greater antioxidant activity retention (78.6–92.1%) as compared to grinding in atmospheric conditions (48.4–68.2%) during storage at all temperatures. Samples ground under vacuum showed delayed or no growth of total aerobic counts, anaerobic bacteria, and mould and yeast, while control groups showed significant microbial growth. Taxonomic composition analysis of samples at day 7 and 25 °C, showed the most abundant bacteria of the control group were from the genus Rahnella belonging to the phylum Proteobacteria, while those of the vacuum-processed groups were from the genus Lactobacillus belonging to the phylum Firmicutes. Consequently, vacuum grinding and packaging can be used in developing technology for preservation of nutritional quality and microbial safety of strawberry puree.