Effects of freezing and thawing on the physical properties and acceptability of tempeh fish ball

Abstract

The main approach of this study was to evaluate the effects of freezing and thawing process on the physical properties and acceptability of tempeh fish ball. Five formulations of tempeh fish ball were developed. These formulations were the incorporation of tempeh in the ingredients at 0%, 5%, 10%, 15% and 20%. Physical analyses were carried out for five freeze-thaw cycles (FTO, FTl, FT2, FT3 and FT4) at every week within 28 days of storage. Tempeh fish balls were analyzed for physical characteristics including color (whiteness index), texture (hardness, chewiness, springiness, and gumminess) and folding test for every freeze thaw cycle. Whereas, only fresh sample (FTO) were analyzed for chemical properties (moisture content, protein, fat, ash, carbohydrate and crude fiber). The chemical composition of tempeh fish balls were ranged from 74.55 to 77.22% of moisture content, 10.78% to 12.43% of protein, 0.55% to 1.07% of fat, 9.13% to 10.51% of carbohydrate, 1.36% to 1.65% of ash and 0.09% to 0.67% of crude fiber content. Increment of the percentage of tempeh incorporation, increased the composition of moisture, ash and crude fiber of the fish ball. On the other hand, the protein, fat and carbohydrate were reduced significantly (p:::0.05). Most of the physical characteristics showed reduction in their values with the increased of tempeh incorporation as well as through freeze-thaw cycles. Microscopic structure showed that freezing and thawing enlarged pore sizes and changed the structure of tempeh fish ball. For the sensory evaluation, the consumer acceptance level of tempeh fish ball were significantly decreased when the percentage of tempeh in the formulations increased as well as when the freeze-thaw cycle increased. Most of the attributes showed the decreasing of acceptability values with the increasing of tempeh incorporation, especially formulation E (20% tempeh). All formulations also showed the reduction of acceptance level after three freeze thaw cycles. Formulations B (5% tempeh) was selected as the most accepted tempeh fish ball as it showed similar acceptance score values with the control (0% tempeh) for the most attributes evaluated.