Fermentation of Soybean Seeds Using Rhizopus Oligosporus for Tempeh Production and Standardization Based on Isoflavones Content

Abstract

Objective: To determine the best temperature and time of fermentation for making soybean (Glycine max (L.) Merril) tempeh seeds with high content of isoflavones. Methods: Five varieties of soybean seeds, Devon-1, Dena-1, Dega-1, Anjasmoro, and Argomulyo, were determined for their isoflavones content using an Ultraviolet (UV) spectrophotometer. A variety containing the highest isoflavones was washed, boiled, peeled, then mixed with tempeh starter (Rhizopus oligosporus culture) at 1 g/kg. The mixture was then poured into plastic bags and flattened with two centimeters of thickness. Fermentation in three conditions: (a) ambient temperature (27-32 °C) without air circulation, (b) 27±0.5 °C, and (c) 30±0.5 °C both with air circulation. The inner temperature, ripening time, and rotting time was recorded. The total isoflavones content was measured every 6 h. Results: The variety of Devon-1 has the highest content of isoflavones (0.112% w/w). Fermentation in condition (a) caused the tempeh too hot(42 °C) and rotted at the 42nd h. Condition (b) produced the best tempeh, ripening at the inner peak temperature (32.5 °C) at the 32nd h; and rotted after the 100th h. Condition (c) produced good tempeh; the ripening occurred at the 31st h at 33 °C and rotted after the 113th h. Tempeh that was produced with condition (b) at the 72nd h has the highest content of isoflavones (0.089% w/w). Conclusion: Fermentation at 27±0.5 °C with air circulation for 72 h produced tempeh with the highest isoflavones content (0.089% w/w), but decrease about 20% compared to its content in seeds (0.112% w/w).

The Enhancement of Isoflavone Aglycones Daidzein and Genistein from Soybean Devon-1 Tempeh through Heat Treatment after 61 Hours of Fermentation

“…This enzyme could produce isoflavone aglycone resulting from the hydrolysis of isoflavone glycosides. 20 The effect of heat treatment on the enhancement of isoflavone had been reported by Hasanah et al, showing increased genistein from tempeh after boiled, steamed, or fried treatment. This suggested that the continuous hydrolysis process of tempeh through the activation of β-glucosidase enzyme by heat.…”

Fibrinolytic Protease Production: Impact of Initial pH and Temperature in Solid-State Fermentation by Rhizopus microsporus var. oligosporus FNCC 6010

“…In addition, at low temperatures, there is a possibility that bacterial contamination grows faster than the growth rate of Rhizopus sp. (Dwiatmaka et al, 2022). Open access article under the CC BY-NC-SA license be used directly as a source of crude enzyme and easily harvested from the media (Sambo et al, 2021).…”

Flour made from cacao-soybean tempeh fermented using soybean tempeh inoculum

“…The process of making tempeh and cacao tempeh flour was performed according to Dwiatmaka et al (2022) with a slight modification. Tempeh was cut into small pieces and dried in a fluidized bed dryer at 45°C for 4 h. Dry tempeh was then ground using food and sieved using 70 mesh.…”

“…In seed pre-treatment, steamer duration was longer for cacao beans than for soybean. The antioxidant agents in cacao beans and soybean are mostly contributed by the polyphenol contents of beans, whose compounds are unstable to heat (Indiarto et al, 2019;Oracz & Nebesny, 2016) and reduced during the processing and fermentation process (Dwiatmaka et al, 2022). Cacao bean fermentation by Rhizopus inoculum might not be performed well as the bean is harder than soybean.…”

“…This process makes soybean tempeh more nutritious because proteins and other compounds are more digestible, and certain vitamins are produced. Rhizopus oligosporus can increase the content of isoflavones during soybean tempeh fermentation (Dwiatmaka et al, 2022). Therefore, it is interesting to conduct further studies on the potential of cacao tempeh as a functional food.…”