Study On The Quality Characteristics Of Quick-frozen Prepared Braised Crucian Carp

Crucian carp has high quality protein and rich amino acid,with high nutritional value and medicinal value.However,the cooking method of crucian carp is single.Crucian carp is cooked only in homes or restaurants,and is rarely available for convenient dishes.With the accelerated pace of modern life and the reduction of cooking time in the kitchen,quick-frozen pre-made dishes are very popular among consumers.The complicated cooking process and many factors in the processing of Chinese dishes will have a great impact on the quality of prefabricated convenient dishes.In this research,quick-freeze prepared braised crucian carp was taken as the research object,the effects of pre-frying conditions,freezing methods and freezing storage time on its quality were studied,and the effects of different reheating methods on lipid oxidation and flavor of quick-freezing prepared braised crucian carp were analyzed.The purpose of this research is to develop quick-frozen prepared braised crucian carp food.Through discussing the quality changes of crucian carp in different processing stages,the research promoted the development of the processing and utilization of crucian carp,and provided a theoretical basis for the research and development of quick-frozen prepared products.According to this objective,the research contents and conclusions will mainly carry out as follows:(1)Effects of pre-frying on quality characteristics of Crucian carpThis research studied the effects of different frying temperature(160℃,170℃,180℃)and frying time(3 min,4 min,5 min)on the quality characteristics of pre-fried crucian carp.The results showed that the yield was 82.67%at 160℃.Water content was 76.41%,TBARS value was 0.81 mg MDA/Kg.At 4 min,the yield was77.99%.Water contentwas 72.40%,TBARS value was 1.79 mg MDA/Kg.The chewiness of fish was significantly increased with the increase of frying temperature and time.The brightness(L~*),reddness(a~*)and yellowness(b~*)of fish at three frying temperatures were 47.08-54.78,2.39-2.57 and 14.21-16.02,respectively.Under the three frying times,the L~*of the fish was 47.74-64.96,the a~*was 0.85-3.00,and the b~*was 11.51-14.36.The p H value increased with the increase of frying temperature and decreased with the prolongation of frying time.In addition,the use of electronic tongue and electronic nose biomimetic sensory technology can better distinguish the smell and taste of pre-fried crucian carp at different temperatures and different frying times.When the frying temperature is 160℃and the frying time is 4 min,the moisture and protein content are high,the p H is about neutral,the TBARS value is low,and the yield rate is good.The hardness and elasticity of fish is moderate,and the fish has good chewability.The fish surface presents golden color,and its color is more acceptable,and in line with the subsequent braising process of pre-fried crucian carp color requirements,so determined as the best pre-fried conditions for subsequent research.(2)Changes of quality characteristics of quick-frozen prepared braised crucian carp during frozen storageThe effects of quick-freezing at-35℃and slow-freezing at-20℃on the quality characteristics of quick-frozen prepared braised crucian carp during frozen storage were compared.The results showed that the moisture content of samples decreased by 1.0%(-35℃quick-freezing)and 3.3%(-20℃slow-freezing)when frozen for 60d.The protein content increased to 22.31 mg/100g(-20℃slow-freezing).The p H values of the quick-frozen samples at-35℃and-20℃reached the maximum value of 6.91 and 6.83 at 100 d and 60 d,respectively,and then decreased significantly.The TVB-N values of-35℃quick-frozen and-20℃slow-frozen samples were 11.47mg/g and 13.37 mg/g,respectively,after frozen for 20 days.When frozen for 100days,the POV values and TBARS values of the quick-frozen sample at-35℃were0.09 meq/Kg and 0.82 mg MDA/Kg,respectively,while the POV and TBARS values of the slow-frozen sample at-20℃were 0.17 meq/Kg and 1.15 mg MDA/Kg,respectively,all of which are greater than-35℃quick-frozen samples.The hardness of the quick-frozen samples at-35℃is 433.17-850.00 g,the elasticity is 2.12-2.71mm,and the chewiness is 6.65-10.57 m J.The hardness,elasticity and chewiness of the slow-frozen sample at-20℃were 542.50-696.00 g,1.95-2.52 mm and 5.70-7.34m J respectively.Compared with slow freezing at-20℃,samples quick-frozen at-35℃had higher water holding capacity,lower TVB-N value,better hardness,elasticity and chewiness,which could effectively slow down fat oxidation and better maintain fish quality.In addition,the total number of colonies of the quick-frozen samples at-35℃reached 3.70±0.01 lg CFU/g after 80 days of freezing,and the quality began to deteriorate,and the electronic nose could well distinguish the quick-frozen fish samples at-35℃under different freezing times.(3)Lipid oxidation and flavor of quick-freeze prepared braised Crucian carp under different reheat braised cooking processesThe effects of two different reheating braised processes(stewed reheating and microwave reheating)on lipid oxidation and flavor substances of quick-frozen prepared braised crucian carp were compared.The results showed that when stewed for 10 min and microwave for 6 min,the maximum POV value was 0.201 meq/Kg and 0.214 meq/Kg.The TBARS value reached the highest value of 0.801mg MDA/Kg and 1.066 mg MDA/Kg when stewing for 5 min and microwave for 8min,and decreased to 0.459 mg MDA/Kg and 0.658 mg MDA/Kg when the time was extended to 10 min,respectively.The POV value and TBARS value of the stewed and reheated samples at different times were lower,and the fish fat oxidation degree was smaller.In addition,electronic nose can distinguish microwave reheating samples at different times well,but it is not effective in distinguishing stewed reheating samples at different times.GC-MS detection showed that there were 154 volatile flavor compounds in fish samples at different processing stages and under different reheating methods,mainly including 17 aldehydes,34 alcohols,and 24 hydrocarbons.The relative contents of aldehydes in the samples that were stewed for 25 min and microwaved for 10 min were higher,which were 11.13%and 12.96%,respectively.The relative contents of alcohols in the samples that were stewed for 20 min and microwaved for 12 min were higher,which were 6.76%and 8.39%,respectively.The relative contents of ketones in the samples that were stewed for 15 min and microwaved for 12 min were higher,reaching 23.36%and 26.42%.There was little difference in the number of flavor substances in the fish samples under different processing methods,and different substances were produced in each processing stage.Among them,there were more kinds of aldehydes,alcohols and esters under microwave reheating method,which had unique flavor.However,harmful substances such as benzene ring compounds are also produced during the processing.