IMPROVING THE QUALITY OF FERMENTED SHRIMP PASTE THROUGH OPTIMIZATION OF FERMENTATION, METAGENOMIC AND METABOLOMIC STUDIES IN THE FERMENTATION PROCESS

• Main Author: Helmi, Henny
• Format: Dissertations
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/67668
• Institution: Institut Teknologi Bandung

Terasi is a fermented product of shrimp which is used as a seasoning in various Indonesian dishes. Products such as terasi or better known as fermented shrimp paste are consumed by the people of China and Southeast Asia as a spice or as a staple food. The differences in raw materials, manufacturing processes, salt content and fermentation time make fermented shrimp paste products diverse in the world. Fermentation involves various microbes and these microbes have a role as a determinant of taste by releasing various metabolites in fermented products which ultimately determine public acceptance of a product. This study aims to standardize the production of shrimp paste to get the best quality of shrimp paste through optimization of the fermentation process (salt content and fermentation time) supported by metagenomic and metabolomics studies. This research is divided into three stages. The first stage aimed to determine the production process, the quality profile of shrimp paste, and the relationship between raw materials, the production process and the quality of shrimp paste in Indonesia. The second stage aimed to standardize the use of salt content in shrimp paste to improve the quality of shrimp paste in Indonesia and determine the community of microorganisms that play a role in the process of making shrimp paste. The third stage was carried out to determine the role of the microorganism community and analyzing changes in metabolites during the process of making shrimp paste in the best quality shrimp paste. The purpose of each stage in this research is achieved by several methods. In the first stage, shrimp identification by Omori method, pH by AOAC method, water content and ash content were tested by thermogravimetric method, salt content by Mohr method, protein content by Kjehdahl method, fat content by hydrolysis method, amino acid test using Ultra High Performance Liquid Chromatography (UHPLC), organoleptic and hedonic tests. In stage II, the bacterial population dynamics was observed using Polymerase Chain Reaction (PCR) in the V3-V4 region and Illumina sequencing. The quality of the shrimp paste was observed, namely salt content, pH, the proximate test, microbial contamination analysis, hedonic test was carried out in the same way as the first stage. In stage III, physiological changes in the bacterial community and metabolite changes in shrimp paste with selected salt content were carried out using EcoPlateTM and with an untargeted metabolomics approach using gas chromatography coupled with mass spectrophotometry (GC/MS). The results obtained in stage I showed that the shrimp paste from various shrimp paste centers had different characteristics. Shrimp used for making shrimp paste are Acetes indicus, A. japonicus, A. vulgaricus, A. sibogae, and Metapenaeus lysianassa. Terasi produced from various regions in Indonesia shows differences in quality which are influenced by the processing method (preservation, fermentation, salting, and drying). The shrimp paste from Toboali centre which made using A. japonicus and initial fermentation for 48 hours is the shrimp paste that has the preferred taste and amino acids. The results in stage II showed the differences in the quality of shrimp paste and bacterial population dynamics in the shrimp paste fermentation process with the addition of 5%, 10%, 15% and 20% salt levels. The shrimp paste with 15% salt meets the standards of SNI 2716:2016 based on the requirements for salt content, water content, protein content, acid insoluble ash content and does not contain pathogenic and putrefactive bacteria during fermentation. The shrimp paste with 15% salt at 21 days of fermentation is the most preferred shrimp paste and meets the sensory standards of SNI 2716:2016. In the initial fermentation (48 hours) and during storage for up to 14 days, the shrimp paste with 15% salt was dominated by Staphylococcus cochnii, Salimicrobium jeotgali, and Corticicoccus populi. At 7 days of fermentation, in addition to these bacteria, Alkalibacillus almallahensis also dominated. At the end of the shrimp paste fermentation with 15% salt (21 and 28 days of fermentation) was dominated by Alkalibacillus almallahensis and Lentibacillus kimchi. The results in stage III showed that there were physiological changes in the bacterial community and metabolite changes during fermentation in shrimp paste with 15% salt. At the beginning of the fermentation (0 to 14 days of fermentation), the activity of the bacterial community was highest in degrading carbohydrate substrates (xylose). At the end of fermentation (21 and 28 days of fermentation), the activity of the bacterial community was highest in degrading the glycyl-L glutamic acid. The sugar group (mannose, ribose, maltose, glucose and N-acetyl glucosamine), the amine group (histamine and 1,3 propanediamine), glutamine, acetoacetic acid and decanoic acid decreased during the shrimp paste fermentation. Amino acid group (tyrosine, methionine, phenylalanine, aspartic acid, N-acetyl valine and N-acetyl leucine), carboxylic acid (lactic acid, glyceric acid and urocanic acid) and behenic acid increased during shrimp paste fermentation. There are several taste precursor compounds and flavor enhancers in shrimp paste with 15% salt, namely glutamic acid, aspartic acid, lactic acid, ribose, dipeptides and the Maillard reaction.