| Although the added value of silver carp(Hypophthalmichthys molitrix)would be improved by processing into surimi produc ts,the demanding for higher quality surim i products is still an ur gent trend.As we all known,high-salt food will cause great damage to the hea lth of human body while the regular-salt content of the traditional surimi products is about 2%~3%.Thus,low-salt surimi products have gradually become a research hotspot in the surimi processing industry.Currently,the ultra-high pressure processing(UHPP)technology is an ef fective and non-therm al processing m ethod which could improve the functional properties and retain the nutritional value of surimi.In addition,carrageenan has been widely used in the surim i products as it can im prove the gel properties.In this dissertation,the improvement of gel properties of surim i on low-salt by the addition of carrageenan a nd the treatment of UHPP was studied.The results are as follows:Compared with the fresh fish mince,the moisture content of frozen surimi increased while the crude protein,crude lipid and ash decreased.In addition,significant decreases in sweet amino acids an d bitter amino acids contents were observed.And except f or small differences in the conten t of sweet am ino acids,bitter amino acids,total amino acid and essential amino acid,there was no si gnificant difference between fresh mince and frozen surimi due to the treatment of UHPP.Using response surface m ethodology(RSM),the results showed that the optim um conditions of low-salt surim i gels by UHPP were 300 MPa at 25 ? for 10 m in.Meanwhile,compared to the low-salt surimi gels(1.5% Na Cl,0.1MPa),the gel strength of the optimized low-salt surimi gels(1.5% Na Cl,300 MPa)increased by 26.04%,and reached 258.24 g·cm,and also significantly higher than that of the stand ard percentage of added salt of surim i gels(2.5% Na Cl,0.1 MPa)(p<0.05),and the water holding capacity(WHC)was also obviously increased(p<0.05).And then,the effect of water properties on gel properties of high pressure processed low salt surimi gel was investigated.The results showed that gel strength and WHC of low-salt surimi gels increased and then decreased significantly as the pressure increased,and reached the maximum values at 300 MPa.It was conspicuous that 300 MPa caused the enhancement of the hydrogen bonding inte ractions,the increase of the bound w ater content and the decrease of the spin-spin relaxation time(T2),which indicated that the percentage of the water increased within the gel matrix.Scanning electron microscopy(SEM)was employed to explain the above results.A more smooth,continuous,uniform and denser three-dim ensional(3D)network structure of low-salt surim i gels was observed at 300 MPa.This structure resulted in retaining a lar ge amount of water and increasing gel strength,ther eby contributing to for ming a good gel in high pressure processed low-salt surimi gel.Finally,the effect of UHP P on properties of low-salt surimi gel containing carrageenan was further studied.The results showed that the gel stren gth and WHC were increased significantly by the addition of carrageenan(p<0.05),and the maximum values were reached at the 0.8%(w/w)carrag eenan.And the hydrophobic interactio ns,disulfide bonds and bound water contents of the pressurized lo w-salt surimi gels containing 0.8% carrageenan in creased significantly at 300 MPa.Moreover,it could cause the transition of ?-helical to random coil depended on promoting the aggregation among the surimi protein molecules.Therefore,the gel properties could be improved in low-salt surimi gels with added carrageenan which were processed under UHPP and obtain better quality of surimi gel. |
PDF Full Text Request