Dominant Enterobacteriaceae in tempeh were primarily originated from soybean

Abstract

During tempeh production, boiling was considered as heat treatment that could significantly reduce or eliminate bacterial population in soybean before fungal inoculation. The objective of this study was to enumerate and trace Enterobacteriaceae communities in pre-boiling soybean, post-boiling soybean, and fresh tempeh designated as RTI and EMP. Standard plate count and qRT-PCR were employed to determine the culturable and non-culturable bacteria, while Enterobacterial Repetitive Intragenic Consensus PCR was conducted to determine the intraspecies genomic variations. Fresh tempeh from both RTI and EMP contained approximately 10 7 and 10 8 CFU/g of Enterobacteriaceae respectively. The number of bacteria in pre-boiling soybean were 10,000 times lower than in fresh tempeh. Our study showed that most Enterobacteriaceae were severely injured or quiescent during boiling process and quickly recovered up to 10 9 CFU/g in fresh tempeh. Some Klebsiella isolates found in tempeh were genetically identical to isolates in soybean, but different from those of medical isolates. This study suggested that soybean could be the main origin of Klebsiella in fresh tempeh.

Tempeh flour as an excellent source of paraprobiotics

“…This proportion was relatively high, similar to the total found in fresh tempeh at 10 log CFU/g (Erdiansyah et al 2021). Moreover, tempeh contained thermophilic bacteria that could survive after heating (Ilham et al 2021). Some bacteria could be in a "quiescent" stationary phase and did not experience morphological differentiation due to environmental stress, such as heating and drying (Rittershaus et al 2013).…”

“…In the Enterobacteriaceae curve, the minor limit reached 3 log CFU, and the number of Enterobacteriaceae calculated in the sample ranged from 5-6 log CFU. The reports of previous research results with a detection limit value of 4 log CFU were used to analyze LAB and Enterobacteriaceae populations in tempeh (Erdiansyah et al 2021;Ilham et al 2021). In several reports, the LAB detection limit value obtained was 2.78 log CFU of L. paracasei from yogurt (Ilha et al 2016), 2-3 log CFU of L. plantarum and L. fermentum in cocoa fruit (Schwendimann et al 2015).…”

“…Some bacteria could be in a "quiescent" stationary phase and did not experience morphological differentiation due to environmental stress, such as heating and drying (Rittershaus et al 2013). The number of Enterobacteriaceae in tempeh flour was approximately 6 log CFU/g, and almost all were culturable (Figure 5); this total was lower than fresh tempeh, at 8 log CFU/g (Ilham et al 2021). The drying process was the main factor in reducing the number of bacteria, but it did not eliminate them.…”

“…While the uncultured method by metagenomic analysis through Quantitative Polymerase Chain Reaction (qPCR) analysis. The qPCR method is very well used to count bacteria in the food matrix and has been used to determine the number of LAB and Enterobacteriaceae in tempeh by other researchers (Erdiansyah et al 2021;Ilham et al 2021).…”

A Training on Tempeh Processing for Dharma Wanita Persatuan Members of LPKA Kelas II Jakarta

“…Salah satu pelatihan virtual yang dapat dilakukan ialah pembuatan tempe kedelai. Tempe kedelai merupakan pangan fermentasi Indonesia dengan bahan baku kedelai (Ilham et al, 2021). Tempe menjadi salah satu sumber protein yang murah dan mudah didapat di Indonesia.…”