Study On The Effect Of Different Freezing Rates On The Quality Of Chicken Soup

Chicken soup has high protein and minerals content,delicious flavor,and has a nourishing effect.It is favored by consumers.However,rich nutrients and high water content also provide a good condition for the growth of microorganisms.It is easy to change the quality of chicken soup during storage.The frozen storage can keep the soup and prolong the shelf life,but the freezing rate has a great influence on it.In this paper,the physical and chemical properties,amino acids,fatty acids and flavor compounds of chicken soup during freezing and frozen storage under three freezing rates were studied to provide theoretical guidance and experimental basis for the freezing process to obtain high-quality chicken soup.The main conclusions are as follows:1.The time through the largest ice crystals formation area were 79.5min,48 min,18min,respectively,when frozen at-20?,-40?,-80?,and the freezing rates were 0.404cm/h,0.822cm/h and 2.070cm/h.2.Effect of freezing rate on the quality of chicken soup after frozen: Compared with fresh chicken soup,after treatment of three kinds of freezing rate(freezing at-20?,-40?,-80?).The pH,soluble protein content decreased significantly(p<0.05);L*,Ytotal,electrical conductivity and TBARS value were increased significantly(p<0.05);apparent viscosity decreased,and the larger the freezing rate,the greater the apparent viscosity.Freezing rate had significant effect on pH,Ytotal,electrical conductivity and TBARS(p<0.05).Freezing at-80? has a positive effect on maintaining good chicken soup quality.The content of saturated fatty acid(SFA)decreased significantly(p<0.05).Unsaturated fatty acid(USFA)were increased to 63.03%,64.09%,65.79%,Freezing at-40? and-80? showed significant difference(p<0.05);The free amino acids were reduced to 236.52mg/100 mL,245.56mg/100 mL,251.7mg/100 mL,respectively,Freezing at-80? had no significant difference(p<0.05);the contents of volatile flavor substances were decreased,The volatile substances of frozen chicken soup loss least when freezing at-80?.Comprehensive judgment,chicken soup freezing at-80? is more clear than fresh chicken soup,little change in quality after freezing.It is helpful to maintain the quality of chicken soup.3.Effect of freezing rate on physical and chemical properties of chicken soup during frozen storage process: Compared with freezing chicken soup,The radioactivity,total plate colonies,TVBN and TBARS of frozen process were significantly increased after three kinds of freezing rate(freezing at-20?,-40?,-80?)(p<0.05);the basic nutritional components soluble protein,total sugar and solids content of chicken soup decreased significantly(p<0.05).Compared to different freezing rates,the higher the freezing rate,the slower the freshness index of chicken soup,the slower the nutrient decrease(p<0.05).The apparent viscosity of chicken soup was decreased during storage,Frozen to 180 d,the larger the freezing rate,the greater the apparent viscosity.Comprehensive judgment,freezing at-80? can delay the quality of chicken soup deterioration rate,inhibit the decline rate of nutrients,help to maintain the quality of frozen chicken soup.4.Effect of freezing rate on amino acid and fatty acid composition of chicken soup during frozen storage process.with the frozen storage time extended,the total amino acids in freezing process which frozen at-20 ? and-80 ? was significantly decreased(p(27)0.05),frozen at-40?showed decreased first and then increased and then decreased;EAA increased first and then decreased and then increased less;SFA increased,USFA decreased.Compared to different freezing rates,the total amount of amino acids and USFA of frozen chicken soup decreased slowly at-80?.Frozen to 180 d,TAA were 1371.02 mg/100 mL,1595.17 mg/100 mL,1713.05mg/100 m L,there was significant difference between different freezing rates(p<0.05);EAA were 266.66mg/100 mL,352.37mg/100 m L,363.42mg/100 mL respectively,the EAA of freezing at-20 ? group was significantly lower than that of the other two groups(p<0.05).SFA were 43.13%,40.22%,39.54%,respectively,and USFA were 56.87%,59.78%,and 60.46%.The results showed that there was amount of frozen storage loss during the freezing and storage process.The greater the freezing rate,the less the loss.5.Effect of freezing rate on flavor substance in chicken soup during frozen storage process.The contents of free amino acids and flavor amino acids were significantly decreased during storage(p<0.05);The content of volatile flavor compounds decreased gradually during storage process of chicken soup(freezing at-20?,-40?,-80?).The content of aldehydes,ketones and alcohols showed a decreasing trend,and the content of acids,hydrocarbons,esters and contents increased.There were significant differences in free amino acids and flavor amino acids between different freezing rates(p<0.05),and the free amino acids,flavor compounds were reduced the slowest in-80?freezing treatment.Frozen to180 d,free amino acids were 138.08mg/100 m L?169.74mg/100mL?197.67mg/100 m L,flavor amino acid were 81.43mg/100 mL,101.65mg/100 m L,110.71 mg/100 m L,volatile flavor compounds were 770.11ug/100 m L,863.76ug/100 mL,862.36 ug/100 mL.It is Indicated that larger freezing rates can reduce the flavor compounds loss in chicken soup.