Penetration of Rhizopus oligosporus into Soybeans in Tempeh

Area of Science:

• Microbiology
• Food Science
• Mycology

Background:

• Tempeh, a fermented soybean food, undergoes significant physical and chemical transformations.
• The Indonesian fermented soybean product tempeh relies on Rhizopus oligosporus fermentation.
• Understanding the interaction between Rhizopus oligosporus and soybean cotyledons is crucial for tempeh quality.

Purpose of the Study:

• To investigate the histological penetration of Rhizopus oligosporus hyphae into soybean cotyledons.
• To quantify the depth and frequency of hyphal penetration in tempeh fermentation.
• To correlate hyphal penetration with observed changes in soybean cotyledons during tempeh production.

Main Methods:

• Histological examination of soybean cotyledons fermented with Rhizopus oligosporus.
• Microscopic analysis to observe and measure hyphal penetration depth and density.
• Quantitative assessment of hyphal infiltration on both outer and inner cotyledon surfaces.

Main Results:

• Rhizopus oligosporus hyphae demonstrated significant penetration into soybean cotyledons.
• Average hyphal penetration occurred at rates of 1 per 1,400 µm (outer) and 1 per 1,010 µm (inner) surfaces.
• Hyphae infiltrated to an average depth of 742 µm, approximately 25% of the cotyledon width.

Conclusions:

• The extensive hyphal penetration of Rhizopus oligosporus into soybean cotyledons is a key factor in tempeh fermentation.
• This deep infiltration provides a partial explanation for the rapid physical and chemical alterations of soybeans during tempeh production.
• Further research can explore the specific mechanisms by which hyphal penetration drives tempeh's characteristic changes.