Spoilage potential of psychrotrophic lactic acid bacteria (LAB) species: Leuconostoc gelidum subsp. gasicomitatum and Lactococcus piscium, on sweet bell pepper (SBP) simulation medium under different gas compositions

Abstract Sweet bell peppers are a significant constituent of retail, chilled-stored and packaged food products like fresh salads, marinades and ready-to-eat (RTE) meals. Previously, through general screening of the Belgian market and by means of source tracking analysis in a plant manufacturing minimally processed, vegetable salads the susceptibility of fresh-cut sweet bell peppers to lactic acid bacterium (LAB) contamination was substantiated. The determination of the metabolic profiles of Leuconostoc gelidum subsp. gasicomitatum and Lactococcus piscium , two major psychrotrophic, spoilage-related LAB species, on sweet bell pepper (SBP) simulation medium under different packaging conditions – 1.) vacuum: 100% N 2 , 2.) air: 21% O 2 , 79% N 2 , 3.) MAP 1 : 30% CO 2 , 70% N 2 and 4.) MAP 2 : 50% O 2 , 50% CO 2 – facilitated a better understanding of the spoilage potential of these microbes as well as the presumptive contribution of O 2 in the spectrum of produced volatile organic compounds (VOCs) associated with poor organoleptic properties of food products. Generally, none of the applied gas compositions inhibited the growth of the 4 L. gelidum subsp. gasicomitatum isolates, however the presence of O 2 resulted in buttery off-odors by inducing primarily the accumulation of diacetyl and pungent “vinegar” smell due to acetic acid. The 3 tested isolates of L. piscium varied greatly among their growth dynamics and inhibition at MAP 2 . They exhibited either weak spoilage profile or very offensive metabolism confirming significant intraspecies diversity.