Bacterial Diversity and Dominant Spoilage Microorganisms in Fresh-Cut Broccoli

Abstract

Different cutting types not only affect the quality and bioactive substances of broccoli but may produce wounding stress that influences the quantity and diversity of microorganisms and finally leads to safety concerns. In this study, three different fresh-cutting types (floret (F), quarterly cut floret (QF) and shredded floret (FS)) and four storage stages (0, 1, 2 and 3 day(s)) were designed to detect the bacterial diversity in broccoli. Results showed that the quantity and growth of microorganisms in fresh-cut broccoli were positively correlated with the intensity of fresh-cut damage, and the 97 strains isolated using 16S rRNA gene sequences were mainly classified into four phyla: Proteobacteria, Actinobacteria, Bacteroidetes and Firmicutes. The predominant phylum was Proteobacteria, dominated by Pseudomonas spp. and Acinetobacter spp. Four representative strains of different species were selected to analyze their spoilage potential on fresh-cut broccoli. Pseudomonas spp. had great impacts on the corruption of broccoli, which affected fresh-cut broccoli by metabolizing to produce nitrite and consuming nutrition. Moreover, Comamonas spp. and Acinetobacter spp. also affected the quality of broccoli, but received little attention previously. This study provides a reference for precise bacteriostasis and preservation of fresh-cut vegetables such as broccoli.