The effect of starter culture on bacterial profile in soybean tempeh

T.E Pramudito,E Paluphi,E.G.A Putri,Y Yogiara

doi:10.26656/fr.2017.5(1).436

Abstract

The bacterial population in soybean tempeh can be affected by many factors such as hygiene and preparation procedure of the soybean. In this study, we investigate the effect of different tempeh starter culture on the bacterial profile in comparison to other factors. The bacterial profile of five commercial tempeh made with different processing techniques and three samples made with different starter culture were analyzed using quantitative polymerase chain reaction (qPCR). The phylum Verrucomicrobia was only detected in commercial tempeh from unstandardized home-scale industries. Bacteroidetes were present in commercial tempeh and samples made with starter that contains cassavabased materials. Commercial tempeh from standardized medium-scale industries contains fewer total bacteria than those from home-scale industries. The addition of starter culture for tempeh production can increase the number of total bacteria compared to uninoculated soybeans. However, there was no difference in total bacterial amount between starter culture variation. Bacterial profiles of all samples were dominated by Firmicutes except tempeh with the starter culture Cap Jago that is dominated by Gammaproteobacteria. This study showed that although the type of starter culture did not significantly contribute to total bacteria in tempeh, it can influence the bacterial profile of the product on phylum level.

Highlights

Tempeh is an Indonesian traditional food made from the fermentation of soybeans by mold as a starter culture, Rhizopus microsporus var. oligosporus
We focused on the ratio of Firmicutes and Gammaproteobacteria considering both phyla make up the majority of the bacterial population in tempeh
We found that the type of starter culture can influence the bacterial phylum profile in soybean tempeh

Summary

Introduction

Tempeh is an Indonesian traditional food made from the fermentation of soybeans by mold as a starter culture, Rhizopus microsporus var. oligosporus. There are five main steps involved in the tempeh production process, namely cooking of soybeans, soaking in water, dehulling, starter culture inoculation and incubation (Efriwati et al, 2013; Seumahu et al, 2013). Mold acts as the main fermenting microorganism in tempeh production, other microorganisms such as bacteria and yeast are present and grow during production. Some of these bacteria play a major role in tempeh production for example during the soaking process. The bacterial population in tempeh has been reported to affect the functionality of the product as immunostimulant (Soka et al, 2014)

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