Study On The Combined Effects Of Ultrasound And Cassava Starch On The Properties Of Low-Salt Grass Carp Surimi Gel And Its Application

Grass carp is an important economic fish species in China,which has long been mainly sold fresh and has a single product range,while its preparation into high value-added surimi products can make full use of resources and improve production efficiency.However,the amount of salt added to traditional surimi products is usually high,which is difficult to meet the consumer demand for healthy low-salt food.Directly reducing the amount of salt used can easily lead to problems such as low gel strength,poor water-holding capacity(WHC)and rough taste.Therefore,this study was conducted to improve the gelation performance of grass carp surimi under low salt conditions by adding cassava starch combined with ultrasonic pretreatment,and use it for the development of flavored fish sausage,in order to enrich the variety of grass carp processed products and promote the development of grass carp deep processing technology.The main results of this paper are as follows:(1)The influence of ultrasound pretreatment with different power,temperature and time on the gel properties of low-salt grass carp surimi were investigated.The actual optimal ultrasound conditions were obtained by response surface optimization: ultrasound power was 220 W,temperature was 6 °C,and time was 35.5 min.The gel strength of surimi obtained under these conditions was 214.98 g·cm,and the WHC was 82.42 %,which increased by 31.97% and 8.73%,respectively,compared with the low-salt control(1.5%Na Cl).In addition,the whiteness,hardness,springiness,cohesiveness and chewiness of the surimi were also improved to different degrees(p<0.05).(2)The influence of cassava starch addition on the gel properties of ultrasonically pretreated low-salt grass surimi was investigated.The results showed that the addition of cassava starch further optimized the gel strength,WHC and texture of the surimi compared with the control group without cassava starch addition(p<0.05),but the whiteness was reduced.The comprehensive evaluation results showed that the addition of cassava starch at7.5% resulted in excellent surimi gel performance with moderate whiteness,and the surimi gel strength obtained under this condition was 338.16 g·cm,WHC was 91.59%,whiteness was 75.65,hardness was 2633.09 g,springiness was 0.956,cohesiveness was 0.674,and chewiness was 1839.44 g.PAS staining The results showed that 7.5% cassava starch was well dispersed in the gel network of low-salt surimi without obvious pores and agglomeration.(3)The influence of cassava starch combined with ultrasonic pretreatment on the conformation and interaction and microstructure of proteins in low-salt grass carp surimi gel was investigated.The results showed that cassava starch combined with ultrasonic pretreatment increased the salt-soluble protein solubilization by 8.23%,and the particle size distribution of myofibrillar protein narrowed and shifted toward small particle size,and the average particle size decreased from 235.10 nm to 209.70 nm with good dispersibility.At the same time,the protein structure was stretched,the percentage of α-helix decreased and the relative content of β-sheet increased(p<0.05),but the molecular weight was not affected.The results of gel solubility and chemical interactions showed that the degree of crosslinking within the surimi gel increased after the addition of cassava starch combined with ultrasonic pretreatment,and the hydrogen bonding,disulfide bonding and hydrophobic interaction indices were all at a high level.The scanning electron microscopy(SEM)results showed that the combined treatment formed a more tightly ordered network structure of the low-salt grass surimi gels compared with the single treatment,which could improve their gel properties more effectively.(4)Based on the previous experiments,the tomato-flavored fish sausage was prepared from low-salt grass carp surimi prepared by adding cassava starch combined with ultrasonic pretreatment,and various supplementary ingredients were added to make tomato-flavored fish sausage,and the orthogonal optimization of the supplementary ingredients formulation was carried out by combining the sensory score and gel characteristics.The results showed that when adding 12.5% tomato paste,10% egg white and 5% sugar,the product had the highest sensory score and good gelling quality.The fish sausage with this formulation was lotus pink in color,with appropriate sugar content and acidity,moderate saltiness,dense and uniform texture,and good springiness and chewiness.