The viability of Rhizopus microsporus APBSMLF19 on different substrates and its application as a starter culture in tempeh fermentation

Abstract

In addition to temperature and incubation time, inoculum is one of the key factors contributing to tempeh’s quality. At several regions in Java, usar, a traditional fungal inoculum obtained from teak leaves, is used for tempeh fermentation, however, there are some lacks in its application. Rice, cassava root and flour, as well as tapioca flour, were evaluated for their suitability as a substrate to support Rhizopus microsporus APBSMLF19 growth (fungi isolated from usar in Gunungkidul, Yogyakarta). About 100 ml/kg of 107 CFU/ml fungi suspension were inoculated to each substrate and incubated at 30 °C for 48 hours. After dried at 50 °C for ± 20 hours and mashed, the fungi viability was observed on weeks 0, 1, 2, and 4 during storage. The result showed no significant difference in the fungi’s number based on storage time for each starter culture’s type, but the inoculum exhibited different viabilities. However, there were no differences in texture measurements for all tempeh produced by using experimental and commercial starter culture (RAPRIMA®). Increasing the culture’s storage time for viability test is required in future research.