Fish Qualify Assessment Based on Glass Transition Temperature (Study case : frozen fish and fish crackers)

Abstract

Some Indonesian fish products have potential prospect for export commodities, :cluding frozen fish and fish crackers products. It has been stated that glass transition -emperature (Tg) can be found rn frozen and dried products. There are limited study on glass ::rnition temperature in relation to their stabilitv on such products. Glass transition ::mperature (Tg) is a physicochemical indicator that can be used to determine quality and r-abrliry* of food including fisheries product. Tg can determine the physical state of the product -n ri'hich it is considered that in glass-v state, the stability of food is in very high condition. The I: of product will be related to water content. Using glass transition parameter, fish product :a1 be evaluated and predicted for its shelf life. Recently, the study of food shelf life in Xndonesia is mainly based on water actir,ity and water content, \rery rare rvas focused on glass :ansition that is very suitable for dried and frozen products. This experiment was conducted :o evaluate the Tg of frozen fish product and fish crackers. Materials used in this experiment rvere yellowfin tw:a (Thunnus albacares) and some Indonesian fish crackers (with different market brand) produced traditionally and some from mdustries. Glass transition temperature was analysed using Differential Scanning Calorimetry IDSC) method and water content of the samples was analysed b5' drying method (AOAC). The results showed that different sample with different characteristics on physicochernical properties give different in water content and also glass transition temperature. Glass ransition temperature (Tg) of the products was depend on the water content and components of the products. Based on the results, Tg of frozen yellowfin tuna was * 63'C and fish crackers and shrimp cracker were in the range of 58.8oC * 76.4'C and 44.l7oc - 62.65oC, respectivelly. The water content of yellowfin tuna was 78% and fish crackers and shrimp cracker were ranged between ll.9o/a - 17.8% and 11.18% - 15.19%