Effects Of Oil-water Mixed Frying On Quality Characteristics Of Prepared Chicken Products And Frying Oil

With the rapid development of social economy and the improvement of people’s life quality,the fried prepared chicken products are greatly popular because of their high nutrition value,convenient consumption and distinctive sensorial characteristics(golden brown color,attractive fried aroma,savory flavor and crispy texture),and their production and consumption are increasing day by day.The fried prepared chicken products are the main direction of accelerated development of meat product.Oil-water mixed frying is to use the mixture of frying oil and water in a frying machine.For the insolubility and the difference in density between oil and water,the mixture layers themselves,leaving oil in the upper layer and water in the lower section.In this way,food residues leave the high-temperature oil before carbonization and descend to water under the action of gravity throughout the frying process,thereby being removed with water in time.Therefore,oil-water mixed frying can retard deterioration of frying oils,extend use-life of frying oils and produce higher quality fried products by reducing food residues in frying oils during frying.Oil-water mixed frying has several unique characters,such as limit control,partition temperature control,automatic filter and self-cleaning.Despite oil-water mixed frying being available in our markets,systematic comparisons of the effects of oil-water mixed frying and conventional pure-oil frying on quality characteristics of fried prepared chicken products and frying oils are not available.In this study,the fried prepared chicken chops and soybean oil were used as the research objects,pure-oil frying was used for comparative studies,and the quality indicators of fried prepared chicken chops and soybean oil were measured in order to evaluate the effects of oil-water mixed frying on quality characteristics of fried prepared chicken products and frying oil.Furthermore,the process of oil-water mixed frying was optimized to improve the quality of fried prepared chicken chops.The contents and results were detailed as follows.1.Effects oil-water mixed frying on quality characteristics of fried prepared chicken chops and soybean oilChanges in quality parameters of fried prepared chicken chops and soybean oil during 48 times of frying affected by oil-water mixed frying(OWF)and pure-oil frying(POF)were comparatively investigated.The results showed that the changes in all quality parameters studied p-anisidine value,carbonyl value,specific extinction coefficients K232 and K268,iodine value,vitamin E content,viscosity,transmissivity,color values(CIE L*and CIE b*values),sensory attributes(color,clarity,odor,flavor,foam and smoke)and area ratio of peak S21 of low-field nuclear magnetic resonance of soybean oil were more pronounced in the case of POF during 48 times of frying,expect free fatty acids.These results indicated that oxidative and polymeric degradation of soybean oil was retard by OWF.In addition,the increase in free fatty acids was more in the case of OWF,indicating that OWF could not decrease the rate of oil hydrolysis.With respect to fried prepared chicken chops,there were no significant differences(P>0.05)in moisture content of chicken chops either between the frying methods or among the frying times.Concerning fat content,significantly higher(P<0.05)values were observed in the last three 8 times in the case of POF than OWF.Meanwhile,OWF led to less decrease in core temperature and crust color(CIE L*,CIE a*and CIE b*values)of chicken chops,and lower acrylamide formation in chicken chops during 48 times of frying.Warner-Bratzler shear force test and Texture profile analysis showed that no significant changes(P>0.05)in Warner-Bratzler shear force and five textural parameters(hardness,springiness,cohesiveness,gumminess and chewiness)of chicken chops due to the frying methods or frying times were detected.Sensory evaluation showed that OWF provided chicken chops with five attributes(color,odor,flavor,texture and overall acceptability)similar to those of chicken chops fried by POF in oil subjected to 8 times of frying.As frying times increased,the decreases in scores for color,odor,flavor and overall acceptability of chicken chops were less in the case of POF.In conclusion,oil-water mixed frying could serve as a worthwhile alternative to traditional pure-oil frying for mitigating the rate of oil oxidative and polymeric deterioration,retarding oil degradation and producing healthier and higher quality fried prepared chicken products.2.Optimization of oil-water mixed frying of fried prepared chicken chops by response surface methodologyBased on the single factor experiments,the response surface methodology was applied to optimize the parameters of oil-water mixed flying,namely,frying temperature and frying time,for prepared chicken chops.The effects of frying temperature and flying time,as well as interaction between the two variables on the moisture content,fat content,CIE b*value and sensory properties of fried prepared chicken chops were investigated.Four quadratic polynomial mathematical models about moisture content,fat content,CIE b*value and sensory evaluation score were built.The results indicated that the responses surface models,with frying temperature and frying time as independent variables and moisture content,fat content,CIE b*value and sensory attributes as responses,were fitted.The moisture content of fried prepared chicken chops was significantly influenced by frying temperature(P<0.01)and frying time(P<0.01).The fat content was significantly influenced by frying temperature(P<0.01),frying time(P<0.01)and frying temperature× frying time(P<0.05).The CIE b*value was significantly influenced by frying temperature(P<0.01),frying time(P<0.01)and frying temperature × frying time(P<0.01),The sensory evaluation score was significantly influenced by frying temperature(P<0.01),frying time(P<0.05)and frying temperature × frying time(P<0.01).According to the models,the optimum quality for prepared chicken chops were obtained when frying temperature was 165℃ and frying time was 210 s.Under such conditions,the moisture content,fat content,CIE b*value and sensory evaluation score of prepared chicken chops agreed with the predicted values.These results indicated that the optimized responses surface models had certain theoretical guiding significance for the actual production.