MFSc

A study was undertaken with the aim of reducing the concentration of cryoprotectants in surimi without adversely affecting stability of the material during frozen storage. The concentration of sugar in commercially produced surimi is generally about 8% which may result in high sweetness in the products prepared. A tropical fish, Nemipterus japonicus (Bloch) was used as the raw material. Minced fish meat was strained, water leached, mixed with different levels (0%, 2%, 4%, 6% and 8%) of sucrose-sorbitol mixture in 1:1 ratio, quick frozen at -35 oC and frozen stored at -20 oC.

Water leaching resulted in a slight absorption of water by meat and reduction in protein, fat and mineral contents. Surimi was found to have a moderately white colour. Sensory evaluation studies were conducted on three products, viz., sausage, patty and cake, prepared using surimi containing different concentrations of sucrose-sorbitol mixture. Sugar content varying from 0% (control) to 4% in surimi resulted in products that were more acceptable to the taste panelists compared to those prepared using surimi with 6% and 8% sugar mixture. A slight sweetness in the product (2% to 4% sugar in surimi) was more preferred by the panelists than their respective controls prepared using surimi containing no sugar.

Frozen storage studies were carried out at -20oC on surimi treated with various concentrations of sugar mixture as mentioned above for a period of five months. pH and total plate count remained nearly steady for all sugar concentrations and throughout the storage period indicating insignificant microbial activity. Moisture content appeared to remain constant during storage, but decreased with increase in sugar concentration probably on account of addition of the sugar mixture. The salt soluble nitrogen content of surimi and gel strength of sausage prepared from it decreased with storage period in all surimi samples, and increased with sugar concentration, while expressible water content of the sausage showed an increasing trend with storage period and a decreasing trend with cryoprotectant concentration. These indicate a greater extent of protein denaturation occurring at low concentration of surimi samples. Sensory evaluation parameters - elasticity, sweetness and preference - remained more or less steady during storage. However, elasticity of sausage prepared from surimi with no cryoprotectant (control) and with 2% sugar level showed a decreasing trend with storage. Elasticity and sweetness increased while preference decreased with cryoprotectant concentration. Elasticity and gel strength seemed to be much lower for control (1.7 and 783.71 g.cm, respectively) compared to even the lowest concentration of sugar (2%) used (2.6 and 886.9 g.cm, respectively). From the study it may be concluded that a concentration of 2 to 4% sucrose-sorbitol mixture is well accepted by the consumers in products such as surimi sausage, patty and cake. At this range of concentration, surimi can be well-preserved in frozen condition at -20oC for at least five months.