Effect and mechanism of thyme microcapsules on histamine production by Morganella morganii MN483274 during the processing of smoked horse meat sausage

Abstract

In this work, we evaluated the effects of thyme microcapsules on histamine accumulation by Morganella morganii both in pure culture and during the smoked horsemeat sausage-making process. To assess the expression of histidine decarboxylase (HDC) pathway-related genes, Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was adopted. Further, relative parameters such as histamine concentration, microbiological growth, and pH were evaluated. Results revealed that thyme microcapsules inhibited the growth of M. morganii, and significantly (P < 0.05) reduced histamine accumulation by inhibiting the expression of histidine decarboxylase (hdcA) and histidine/histamine antiporter (hdcP) genes. However, it had minimal influence on the expression of the histidyl-tRNA synthetase (hdcRS) and hdcB genes in HDC clusters. Thyme microcapsules exhibited markedly higher (P < 0.05) inhibitory potential than thyme essential oil. Hence, thyme microcapsules should be added in the production process of traditional Chinese smoked horsemeat sausages.