Gas chromatography-mass spectrometry-based metabolite profiling and sensory profile of Indonesian fermented food (tempe) from various legumes.

Tempe is an Indonesian fermented food prepared from soybean or other non-soy legumes. Non-soy legumes based tempes have been reported to have a nutritional profile different from that of soybean-based tempe. However, a comprehensive study of the metabolite and sensory profiles of legume tempes has not been conducted. This study investigated the metabolite profile of legumes before and after fermentation using a metabolomic approach and its relation to the sensory profile. Four different legumes, namely red kidney bean, soybean, cowpea bean, and jack bean, and four kinds of tempe prepared from the abovementioned legumes were subjected to gas chromatography-mass spectrometry (GC-MS) analysis. These tempe samples were fermented in two different production places, Japan and Indonesia. In total, 83 metabolites were annotated from all samples. Principal component analysis (PCA) showed that the samples were separated based on their type (legume and tempe) along PC1 with a 36.3% variance, in which sugars and amino acids significantly contributed to the separation. In addition, samples were separated along PC2 with a 17.2% variance based on the different production places. The combination of 75% soybean and 25% red kidney bean (75S:25R) could increase the concentrations of amino acids that were initially low in soybean tempe. The 75S:25R tempe showed no significant differences in taste and texture preference compared to the 100% soybean tempe, based on sensory result. These findings provide evidence that metabolomics could be used to identify the differences between tempes from different legumes.