Changes in bacterial loads, gas composition, volatile organic compounds, and glucosinolates of fresh bagged Ready-To-Eat rocket under different shelf life treatment scenarios

Abstract

Temperature abuse and improper shelf life treatment of Ready-to-Eat wild rocket is a leading cause of product quality losses and consumer rejection. It can cause the deterioration of appearance, the build-up of bacterial numbers, and the production of off-odours. This study subjected commercially produced and processed bags of wild rocket to various temperature and shelf life duration treatments that could hypothetically be experienced by a consumer, purchasing bags from supermarkets that have suffered cold-chain breaches. We take a unique experimental perspective that accounts for potential temperature variation scenarios within supermarkets and the home. Bacterial counts, volatile organic chemical production, glucosinolate concentration, and internal bag atmosphere composition were measured under these temperature scenarios and across growing seasons. Our results showed that the season of purchase significantly affects wild rocket respiration and bacterial loads. Prolonged high temperature abuses increased microbial loads, disulfide abundance, and reduced content of the glucosinolate glucoerucin. Short temperature abuse treatments resulted in no significant changes in bacterial numbers, providing bags were returned to cool-chain conditions. Samples stored under these conditions (<5 °C) saw no significant changes. The effect of growth season also significantly affects wild rocket respiration. Summer-grown produce had high bacterial loads, but winter-grown had a higher respiration rates. These data illustrate the importance of maintaining cold-chain conditions for wild rocket to preserve key glucosinolate compounds and prevent sulfide formation via bacterial propagation and anaerobic respiration.