จิรชัย เลขาวิจิตร. ผลของภาวะในการเกิดเจล ความสดของปลา และระยะเวลาการเก็บรักษาซูริมิแช่แข็งต่อสมบัติของเจลซูริมิจากปลาทับทิม Oreochromis niloticus X O. placidus. ปริญญาโท(เทคโนโลยีทางอาหาร). จุฬาลงกรณ์มหาวิทยาลัย. สำนักงานวิทยทรัพยากร. : จุฬาลงกรณ์มหาวิทยาลัย, 2547.
ผลของภาวะในการเกิดเจล ความสดของปลา และระยะเวลาการเก็บรักษาซูริมิแช่แข็งต่อสมบัติของเจลซูริมิจากปลาทับทิม Oreochromis niloticus X O. placidus
Effect of gelling condition freshness of fish and storage time of frozen surimi on properties of ruby tilapia Oreochromis niloticus X O. placidus surimi gel
Abstract:
The objective of this study was to investigate the effects of heating conditions, freshness of fish and storage time of frozen surimi on properties of ruby tilapia surimi gel, as well as the effect of fish proteases on myosin heavy chain (MHC) of the fish protein. A heating condition that resulted in surimi gel with highest gel strength was first studied. A combination of seven heating temperatures (40, 45, 50, 55, 60, 65 and 70 °C) and four heating time periods (30, 60, 90 and 120 minutes) was used in the first step of surimi gel preparation, followed by a second step heating at 90 °C for 30 minutes. Gel strength was affected by heating temperature, heating time and the combined effect of heating temperature and heating time (p < 0.05). Maximum gel strength (1083.51-1121.07 g.cm) was obtained when heated at 40 °C for 90-120 minutes (p > 0.05). Surimi gels that were heated at 65 °C possessed minimum gel strength. The gel strength decreased with increasing heating time (i.e., 462.92 g.cm at 30 minutes of heating and 207.41 g.cm at 120 minutes of heating) (p ≤ 0.05). Different heating conditions had no effect on the whiteness of surimi gels (p > 0.05). These results were in good agreement with the study of the effect of proteases on MHC of the fish protein. At 40 °C, the changes in the intensity of MHC band were not observed within the range of heating periods studied (0-120 minutes). At 65 °C, the intensity of the MHC band decreased with increasing heating time. For the study of the effect of the fish freshness on the quality of the surimi gel, it was found that the fish at 0 day of storage (TVB = 11.08 mg/100 g sample, TMA = 0 mg/100 g sample) yielded surimi gel with the highest gel strength (1152.42 g.cm) and high value in whiteness (79.07). Surimi gels obtained from fish kept in ice for 5 days possessed lower gel strength (840.66 g.cm) and lower value in whiteness (77.29). There was no difference in gel quality as evaluated using a folding test. Gels produced from surimi kept in frozen storage (-20 ± 2 °C) exhibited reduced gel strength and salt extractable protein content with increasing frozen storage time from 0 to 9 months (p ≤ 0.05). However, frozen storage time had no significant effect on the gel whiteness and the quality of surimi gel as evaluated using a folding test (p > 0.05).