Study On The Quality Stability Of Ready-to-eat Isinglass

Isinglass is the dried product of swim bladder and precious food raw material with rich nutritional value.With people’s pursuit of health and convenience in eating,the market of ready-to-eat isinglass products has increased gradually in recent years,but the problem of soft texture will occur in the storage of ready-to-eat isinglass,which greatly destroys the quality.Therefore,this study took the ready-to-eat isinglass products as the object,systematically studied the influence of key processes such as rehydration,pretreatment and sterilization,on the quality of ready-to-eat isinglass,and explored the quality change of ready-to-eat isinglass at different storage temperatures.The results of the experiment can provide technical support for the development of high-quality ready-to-eat isinglass.1.The effects of rehydration temperature and time on the quality of ready-to-eat isinglass were studied.The results showed that under the condition of 100℃,the isinglass had good rehydration degree,and the moisture content of isinglass reached 62.86%after 10 min of rehydration,but with the increase of rehydration time,the collagen content decreased(compared to the blank group decreased by 8.66 g/100 g),accompanied by deterioration of texture.After the isinglass was soaked at 4°C and25°C for 12 h and 4 h respectively,the moisture content of isinglass was finally stabilized at 56.32%and 55.46%,and after sterilization,the ready-to-eat isinglass had higher collagen content and better texture compared with 100°C.At 4℃and 25℃,the flavor of ready-to-eat isinglass changed with the rehydration time,and the flavor change was more significant at 25℃.2.The stability of different additives on the quality of ready-to-eat isinglass during storage was studied.The results showed that calcium chloride and TGase had no significant effect on the texture of ready-to-eat isinglass.It was found that the addition of tea polyphenols decreased the L*value of ready-to-eat isinglass and increased the a*value and b*value.With the increase of concentration of tea polyphenols,the water holding capacity of ready-to-eat isinglass improved,while the moisture content and relaxation time of water reduced.When the concentration of tea polyphenols was 1.0%,the water holding capacity reached 93.15%,the moisture content was 77.67%,and the relaxation time of immobilized water was 74.74 ms.When the concentration was 0.6%,the texture and collagen content of ready-to-eat isinglass were significantly better than those of the blank group.After 12 days of storage at 37°C,the hardness,stickiness and shear force were 21.81 g,-2.87 g and 27.57 g·s respectively,and the collagen content was 16.11 g/100 g(compared with the blank group,which increased 6.07 g/100 g).At the same time,the stability of the secondary structure of ready-to-eat isinglass increased.Compared with the blank group,the random coil content decreased from 32.28%to 22.73%,and the content ofα-helix andβ-sheet increased from 28.72%to 34.63%and 24.64%to27.75%.3.The stability of the sterilization process on the quality of ready-to-eat isinglass during storage was studied.The results showed that at the same sterilization temperature(121℃),with the increase of sterilization time,the quality of ready-to-eat isinglass deteriorated significantly.Under the sterilization intensity of F=4.5 min,the ready-to-eat isinglass sterilized at different temperatures can all ensure commercial sterility,and the L~*value increased during storage.The texture of ready-to-eat isinglass improved with the increase of sterilization temperature.After sterilization at 125°C,the hardness and shear force of ready-to-eat isinglass were the biggest,and the stickiness was the smallest,which were37.02 g,34.41 g·s and-2.82 g,respectively.At the same time,the heat denaturation temperature of the ready-to-eat isinglass sterilized at 125℃was the highest,which was 37.9℃.After being stored at37°C for 12 days,the 125°C group had the lowest moisture content,the highest water holding capacity,and the smallest relaxation time of free water,and the collagen content in the sample was8.11 g/100 g(compared to the 110°C group,which increased by 4.86 g/100g),the collagen content in the solution was 35.57 mg/m L(compared to the 110℃group,which decreased by 43.32 mg/m L).There was no significant difference in the protein secondary structure of ready-to-eat isinglass sterilized by different sterilization temperatures,and the proportions ofα-helix,β-sheet and random coil were similar.4.The effect of storage temperature on the storage stability of ready-to-eat isinglass was studied.The results showed that during storage,volatile base nitrogen and p H values remained stable.Above25℃,the hardness and shear force reduced with the increase of temperature,accompanying the degradation of protein and the increase of water content.The deterioration of quality above 30℃was more notable.Below 20℃,the texture of ready-to-eat isinglass did not change notably,and the protein and water state were stable.At 20°C,after storage for 36 days,the hardness and shear force of ready-to-eat isinglass were 14.51 g and 18.27 g·s,respectively,the moisture content was 87.65%,and the collagen content was 10.37 g/100 g.