PRELIMINARY OBSERVATION OF FUNGAL CONTAMINATION IN PEANUT TEMPEH FERMENTATION: CHALLENGES IN SMALL-SCALE PRODUCTION

Abstract

Tempeh is a traditional fermented cuisine, generally produced from soybeans and Rhizopus spp., with great nutritional content and functional health advantages. In recent years, the increasing demand for locally available, sustainable and cost-effective protein sources has led to significant interest in developing non-soy tempeh using alternative substrates such as peanuts. Although peanut-based tempeh has been suggested as a substitute for soybean tempeh, there is insufficient empirical investigation of the fermentation behaviour, failure mechanisms and process stability of peanut substrates under controlled small-scale production circumstances. This study was conducted to investigate the fermentation behaviour of peanut tempeh and to determine the possible reasons for fermentation failure, with the practical relevance in small-scale and community-based production. Peanut substrates were inoculated with commercial Rhizopus starter and fermented under ambient conditions. The fermentation process was tracked over a period of three days using visual observation, temperature profiling and pH testing. The results showed that the fermentation did not occur. On Day 1 there was little mycelial development seen, peanut kernels were loose, and surface wetness was present. By Day 2 it showed greyish mycelial development, uneven colonisation and increasing condensation. By the third day, there was heavy contamination with grey-black mycelium and green-yellow patches of fungus, and this was a complete failure of fermentation. The temperature profile was non-linear with an increase from 26.18°C to 31.01°C on Day 1, decrease to 29.29°C on Day 2 and increase again to 31.22°C on Day 3. In addition, pH increased from 5.46 to 6.62, indicating alkaline conditions consistent with microbial deterioration. The observed failure in fermentation might have been caused by insufficient compacting of the substrate, uneven moisture distribution and inappropriate fermentation conditions. Nevertheless, further controlled experiments are necessary to confirm these contributing factors. Results from the point of view of small-scale production show practical difficulties in adapting peanut tempeh for small-scale and community production where control over the process is limited. These results provide a basis for the optimisation of fermentation techniques and improved practicality of peanut-based tempeh as a sustainable alternative protein product for community-scale production.