Effects of fermentation time on chemical, microbiological, antioxidant, and organoleptic properties of Indonesian traditional shrimp paste, terasi

Terasi is a traditional fermented shrimp paste from Indonesia. It is commonly used in the preparation of sambal terasi, a traditional chili sauce. This study aimed to: (1) investigate the microbiological and chemical changes occurring during the fermentation of terasi for 90 days and (2) analyze the antioxidant activity and sensory acceptance of sambal terasi prepared from shrimp paste fermented for different durations. The microbial load increased during fermentation and was highly dominated by halophilic bacteria. The number of lactic acid bacteria decreased at the final stage of fermentation. While the pH fluctuated, the moisture content and water activity did not change during fermentation. According to its water activity (0.634–0.663), terasi is considered as an intermediate moisture food. Protein degradation and lipid oxidation took place during fermentation, as shown by the increase in TCA-soluble peptides and TBARS. Such processes contributed to the flavor development in terasi. In addition, the formation of potential toxic compounds also occurred during the fermentation of terasi, including histamine from protein degradation and acrylamide from the Maillard reaction. Terasi had a negligible antioxidant activity. However, sambal terasi had a strong antioxidant activity due to the presence of chili peppers and other spices rich in antioxidants. The sensory testing revealed consumer preference for sambal terasi prepared with shrimp paste fermented for a longer period (60–90 days). However, due to food safety reasons, it is preferred to opt for a shorter fermentation time of terasi (7–21 days).