Image analysis for monitoring the barley tempeh fermentation process

Tempeh: A semicentennial review on its health benefits, fermentation, safety, processing, sustainability, and affordability

Tempeh is a fermented food made of mainly soybeans and is a nutritious, affordable, and sustainable functional source of protein. Globally, tempeh is a widely accepted fermented product. Although there is a growing body of literature on tempeh, most research has focused on unfermented soybeans, thus the impact of tempeh fermentation on biological properties of soybeans has been largely left scattered. The objective of this review is to summarize the literature of tempeh fermentation over the past 60 years. A search of articles on tempeh published from 1960 to 2020 was performed using the Cochrane Library, Web of Science, EBSCOhost FSTA database, and Google Scholar. References from identified articles were reviewed for additional sources. In total, 321 papers were selected for this review, of which 64 papers were related to the health benefits of tempeh. This review concluded that sufficient evidence exists in the literature supporting tempeh fermentation as a low-cost, health-promoting, and sustainable food processing technology to produce protein-rich foods using various beans, legumes, and grains. This comprehensive review suggests further studies are needed on tempeh fermentation and its impact on human health; research and standardization of nonsoy tempeh; assessment of food safety-improving modification in tempeh production system; and initiatives supporting the sourcing of local ingredients in tempeh production.

Controlled fermentation of rapeseed presscake by Rhizopus, and its effect on some components with relevance to human nutrition

The use of rapeseed protein could contribute to meeting the increasing demand for plant proteins with high biological value in human nutrition. In order to make rapeseed presscake fit for human consumption, the presscake was fermented by using the tempeh mould, Rhizopus microsporus var. oligosporus. Fermentation was satisfactory at initial levels of added acetic acid of 40-60 mmoles/Kg, a_w of 0.97, pasteurization, surface inoculation and incubation at 32 °C and 90-95% relative humidity. It was crucial to stop the fermentation once the mould had grown and metabolized sufficiently but before a major rise in pH and subsequent growth of acid-sensitive sporeforming bacteria occurred. Some degradation of glucosinolates, cell wall polysaccharides and phenolic compounds was found, but there was some evidence that growth and metabolism of the mould also depended on the texture of the presscake, as these factors affect the oxygen supply to the mould. In conclusion, it is possible to ferment rapeseed presscake by using the "Tempeh starter" Rhizopus oligosporus, but in order to use the resulting product to enrich various foods with protein or replace other proteins, the degree of degradation of undesired compounds should be further standardized, especially by the control of the pH, oxygen supply, and fermentation time.