Diversity of Fish Terasi Collected from Various Regions in Indonesia Based on Physicochemical Characteristics

Abstract

Terasi, a fish or shrimp paste, has been studied as a naturally fermented product with delectable flavor that is frequently used as a seasoning for food. Besides, terasi is frequently used in Indonesian cuisine to enhance the flavor. There are various places in Indonesia where fish paste is produced, and each producer may use a different manufacturing method in making terasi its-self. Variations in the materials, salt concentration, duration of fermentation and drying give impacts on the physicochemical characteristics such as proximate, NaCl, titratable acids, nucleotides, total amino acids, free glutamic acid, pH, activity of water, texture, color and FTIR profile. The manufacturing procedures of fish paste production include drying the raw materials, grinding the dried components, adding the water, and fermentation from 2 weeks to 8 months. The unique and complex flavor of the paste is produced by microbial growths which allow enzymatic reactions during fermentation. Information regarding the chemical and physical characteristics of fish terasi from various regions in Indonesia is still limited. The objective of this study was to characterize fish terasi products based on the physicochemical attributes and to map the chemical characteristics through multivariate analysis to determine the diversity of fish terasi. Proximate composition, NaCl, total titratable acid, pH, total amino acids, free glutamic acid, nucleotides (AMP and IMP), texture, color and water activity of ten samples of fish terasi collected from different producers in Indonesia, were analyzed. Fish terasi samples used in this study had the average of proximate composition, such as moisture content of 29.77% (wb), ash content of 22.70% (wb), fat content 4.08%, protein content of 33.97% (wb) and carbohydrate of 10.68% (wb). Additionally, the average of free glutamic acid, adenosine monophosphate and (AMP) and inosine monophosphate (IMP) were 0.14% (wb), 0.72% (wb), and 0.17% (wb) respectively. Furthermore, the average of other chemical compositions such as NaCl, total titratable acid was 11.45% (wb) and 3.27% (wb) respectively. Besides, the average of pH and water activity (aw) obtained were 6.67 and 0.7 respectively. Therefore, fish terasi is classified into medium risk food. Fish terasi samples were divided into four groups based on principal component analysis (PCA) on proximate composition data: samples from Rembang (Central Java), Majalengka and Pangandaran (West Java), and Sumenep (East Java) characterized by fat content; samples from Indramayu (West Java), Jember and Sidorajo (East Java) characterized by protein content; samples from Lampung (Southern Sumatera) and Bekasi (The samples classified according to protein concentration were grouped together in the mapping result based on FTIR spectra (400-1500 cm-1). Umami compound mapping revealed that sample from Majalengka was defined by AMP and IMP, whereas samples from Jember, Sumenep, and Pangandaran were characterized by free glutamic acid. The umami taste of fish terasi samples was predicted from equivalent umami concentration (EUC) in g free Glu per 100 g terasi (wet basis). Sample from Majalengka showed the highest EUC (470), followed by that from Indramayu (297), Ogan Ilir (207) and Sidoarjo (154). Other samples had EUC lower than 100. Therefore, samples having relatively high proteins and nucleotides are potential for umami research. Keywords: fish terasi, fish paste, umami, amino acids, free glutamic acid, AMP, IMP, EUC, UPLC, FTIR