Identification of the bacteria and their metabolic activities associated with the microbial spoilage of custard cream desserts

Abstract

The famous French dessert "ile flottante" consists of a sweet egg white foam floating on a vanilla custard cream, which contains highly nutritive raw materials, including milk, sugar and egg. Spoilage issues are therefore a key concern for the manufacturers. This study explored the bacterial diversity of 64 spoiled custard cream desserts manufactured by 2 French companies. B. cereus group bacteria, coagulase negative Staphylococcus, Enterococcus and Leuconostoc spp. were isolated from spoiled products. Thirty-one bacterial isolates representative of the main spoilage species were tested for their spoilage abilities. Significant growth and pH decrease were observed regardless of species. While off-odours were detected with B. cereus group and staphylococci, yoghurt odours were detected with Enterococcus spp. and Leuconostoc spp. B. cereus group bacteria produced various esters and several compounds derived from amino acid and sugar metabolism. Most Staphylococci produced phenolic compounds. Enterococcus spp. and Leuconostoc spp. isolates produced high levels of compounds derived from sugar metabolism. Each type of spoilage bacteria was associated with a specific volatile profile and lactic acid was identified as a potential marker of spoilage of custard cream-based desserts. These findings provide valuable information for manufacturers to improve food spoilage detection and prevention of chilled desserts made with milk and egg.

Avaliação sazonal da temperatura de iogurtes comercializados em um hipermercado de um município da Baixada Santista/SP / Seasonal evaluation of the temperature of yoghurts sold in a hypermarket in a municipality in Baixada Santista/SP

“…Diversos microrganismos já foram detectados e relacionados a deterioração de iogurtes, causando alterações de diversos aspectos ao produto como, estufamento, alteração de cor, sabor e aroma, sendo estes responsáveis por uma grande parte da perda destes alimentos (MOREIRA et al, 1999;TECHER et al, 2020).…”

“…A manutenção da vida, velocidade de crescimento e produção de enzimas, pelos microrganismos depende de uma faixa ideal de temperatura, por isso se faz tão importante Brazilian Journal of Development, Curitiba, v.7, n.4, p. 43481-43489 apr 2021 o controle de temperatura dos alimentos, principalmente aqueles que já possuem microrganismos em sua composição, como a maioria dos derivados lácteos, desde sua produção até seu armazenamento nos comércios ou na casa do consumidor (TECHER et al, 2020).…”