Effects of Ɛ-Polylysine Combined with Plant Extract on the Microbiological and Sensory Qualities of Grapes

Grapes are prone to rot and deterioration during storage, seriously affecting their food value. The effects of five extracts, cinnamon, perilla, green tea, pomegranate peel, and ginger, on the microbial growth, weight loss, and sensory quality of grapes were investigated using colony counting and sensory scoring methods. The results showed that perilla and cinnamon extracts had the best effect on maintaining the overall freshness of grapes on the 35th day of storage. The sensory scores were 82 and 80, respectively, and the number of microorganisms was below 6.13 log CFU/g. Further studies revealed that the combination of perilla and cinnamon extracts with Ɛ-polylysine resulted in better inhibition of microbial growth, reduced weight loss, maintained grape quality, and extended storage period to 40 days. An analysis of the active ingredients of the perilla and cinnamon extracts revealed that both extracts contained active antioxidant and antimicrobial ingredients, such as protocatechuic acid, coumaric acid, protocatechuic aldehyde, and rutin. The active ingredients of the perilla extract also included luteolin and apigenin, and those of the cinnamon extract included pinocembrin and epicatechin. These ingredients were deduced to have contributed to preserving the freshness of grapes by the plant extracts.