Reuse of tempeh fermentation: a promising protein source using food byproduct and edible filamentous fungi.

The growing global population and increasing demand for food pose a challenge for sustainable food production. Traditional methods, especially those based on animal proteins, have a significant environmental impact. To address these challenges, alternative protein sources such as single cell proteins (SCPs) have emerged that can be produced using microbial cultures. Edible filamentous fungi offer a promising opportunity for SCP production and can be grown on agroindustrial residues such as spent grains, thereby upgrading protein content and improving the quality of fermented foods.

1. spent grain: a valuable substrate for tempeh production

Treber meal is a by-product of the brewing industry and accounts for over 80 % of the residues produced. Normally used as animal feed, spent grain contains high protein content and dietary fiber, making it an attractive candidate for upgrading processes such as single cell protein (SCP) production. In this study, researchers from the Politecnico di Torino propose converting spent grain into a valuable protein source through tempeh fermentation.

2. use of edible filamentous fungi for solid-state fermentation.

The solid-state fermentation (SSF) process involves the use of the filamentous fungus Rhizopus oligosporus to convert spent grain into tempeh. This process aims to increase the protein content of spent grain and improve its nutritional value. To start SSF, an inoculum of Rhizopus oligosporus is prepared using a powdered commercial tempeh starter culture spore and organic rice flour.

3. experimental setup and analytical measurements

The SSF tests were performed with a small-scale fermenter, adjusting various parameters in each batch, such as temperature, inoculum content, mass of spent grains, and the interface. The fermentation process lasted 5 days. Several measurements were made during the process to analyze the fermentation products and evaluate the protein content compared to raw spent grain. Proximate analysis, pH, titratable acidity (TA), degrees Brix (°Bx) and protein content were measured using homogenized liquid samples prepared from fresh spent grain and fermented spent grain.

Clitec climate chambers: Promoting tempeh production

Clitec’s advanced climate chambers can play a crucial role in the production of tempeh. These chambers provide precise control over temperature, humidity and other environmental factors, creating optimal conditions for the growth and fermentation of filamentous fungi such as Rhizopus oligosporus. By using Clitec climate chambers, producers can ensure consistent and efficient tempeh production, maximize the protein content of spent grain and reduce environmental impact.


Repurposing technology enables efficient use of food scraps and edible fungi for protein production, especially in tempeh fermentation. Cultivation of Rhizopus oligosporus in solid-state fermentations shows a significant increase in protein content. The fermentation process can be optimized by adjusting operating parameters such as temperature, inoculum ratio and amount of BSG substrate.

The use of Clitec climate chambers plays a crucial role in this process, as they provide optimal growth conditions for tempeh culture through precise control of temperature, humidity and other environmental conditions. Clitec climate chambers enable reproducibility and precise control of the fermentation process and support sustainable protein production. Collaboration with companies like Clitec promotes the further development and application of this technology in the food industry. Further research and development are needed to realize the full potential of this innovative technology and maximize its impact on the sustainability of food production.


Gomez-Camacho, C. E., Mollea, C., Mazzarino, I., Ruggeri, B., & Bosco, F. (2022). Repurposing Tempeh Fermentation: a Promising Protein Source Using Food Residues and Edible Filamentous Fungi. Chemical Engineering Transactions, 93, 37-42.