The quality and chemical characteristics of dried rabbitfish products in Penghu and their changes during storage

• Main Authors: Yu-Ching, Lai, 賴鈺菁
• Other Authors: Shiau, Chyuan-Yuan
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/74688621454757714844

碩士 === 國立臺灣海洋大學 === 食品科學系 === 103 === Rabbit fish is a common species of fish in Penghu. Because of special flavor and more inexpensive, rabbit fish has been made into dried product and sold in the market. Traditionally, dried rabbit fish is one of the important fishery products in Penghu area. There is a few report on the variable quality of dried rabbit fish; therefore, this study is designed to investigate the hygienic quality and chemical compositions of the products sold in local markets, fishing villages and fishing ports in Penghu. In order to understand its storage stability, changes in freshness quality and chemical compositions of the products during storage at 25℃ were studied as well. Results showed that total plate count (TPC) of 10 samples of dried rabbit fish ranged from 4.28 to 7.17 log CFU / g, of which two products do not meet the hygienic limit of 3 × 106 CFU / g. The samples possessed volatile basic nitrogen (VBN) ranged 44.6 - 210.4 mg / 100 g, higher than 25 mg / 100 g of the limit. Results revealed that the manufacturing process and storage method of commercial dried rabbit fish need to improve. Most individual free amino acids (FAA) of dried products were more than those of raw fish, of which taurine, alanine, glutamic acid were predominant ones. The increase in FAA enhances the taste of dried fish products. The VBN, trimethylamine (TMA), pH value and TPC were higher than raw fish. The POV and TBA values of dried pruduct were 56.27 meq / kg fat and 4.38 MDA / Kg, which were much higher than 1.63 meq / kg fat and 0.99 mg MDA / Kg of raw fish; showing processing obviously cause lipid oxidation of dried fish. The pH, TMA, VBN, TPC and K value of dried rabbit fish increased with time during storage at 25℃. Providing thorough drying process extended the shelf-life of dried product storing at ambient temperature. However, enzymatic action may result in low quality of the product after prolonged storage. Results from the freshness quality indicators reveal dried rabbit fish is not suitable for long-term storage at ambient temperature. Low temperature such as refrigeration or frozen storage was better way to maintain better hygienic quality.