Quality Changes after Oven-drying and Frozen Storage of Bluestripe Herring (<i>Herklotsichthys quadrimaculatus</i>)

Abstract

Proximate composition (moisture, ash, protein, and fat) of muscle tissue and small, medium, and large sizes bluestripe herring (Herklotsichthys quadrimaculatus) were analyzed. The fresh index of all three sizes bluestripe herring was monitored every month during six months frozen storage (-20°C). Small-sized specimens spoil faster than the larger ones; therefore it is mostly processed into dried products right away and sold in the market in dried form. As two of the often-used methods, oven and sun drying of small bluestripe herring were compared for their water activity and moisture changes, freshness index values (pH, Thiobarbituric acid (TBA), and Total volatile basic nitrogen (TVBN)), and overall acceptability. pH and TVBN values indicate that bluestripe herring (all sizes) are still under fresh index value in fresh condition even after 6 month storage at -20°C, but considering the TBA values, the fish are considered best to consume when fresh or at most before 1 month at -20°C frozen storage. The fish oven-dried at 80°C gave lower TVBN amount than sun dried fish, and both values are still considered suitable for human consumption. Their pH, TVBN and TBA values showed significant difference. The fish oven dried at 60°C and 80°C received a higher score by panelists than sun-dried fish. Oven drying at 80°C can be an alternative to traditional sun drying as it is time saving. Frozen storage still considered as the best method for mitigating quality changes of bluestripe herring.