Apple Waste Preservation for Extraction of Antioxidants

Abstract

A huge amount of apple waste is generated from juice, cider and other apple product industries. This waste represents a cost and causes environmental problems. Apple waste is a rich source of polyphenolic compounds, mostly found in the apple peels and cores. Polyphenols are antioxidants with high value that can be extracted from the waste and exploited commercially. Proper methods of waste pasteurisation would allow its preservation and reduce waste degradation. In this study, diluted apple waste was pasteurised using three different technologies: thermal processing (TP), high pressure processing (HPP) and low pressure assisted thermal processing. The effect of processing on the waste native yeasts and moulds, inoculated Saccharomyces cerevisiae yeast and antioxidants were investigated. TP at 60, 80 and 100 °C for 30 min, HPP at 300, 400 and 500 MPa for 10 min and 600 MPa for 20 min, and low pressure assisted thermal processing at 60, 80 and 100 °C with 2 MPa for 30 min were carried out. The total yeasts and moulds initially in the diluted apple waste was about 6.6×101 cfu/g, which was fully inactivated by the three technologies. S. cerevisiae inoculated in the waste was reduced by 5-log or more with all processing methods/conditions. HPP and low pressure assisted thermal processing treatments did not affect the antioxidant activity (DPPH-radical scavenging). However, both TPC and DPPH radical scavenging decreased with TP (p < 0.05). The results of this study can be helpful for designing appropriate conditions to pasteurise fruit industry byproducts for further extraction of high value antioxidants.