Quality Changes Of Pork Oil During Stewing And Effects On Physiology Of Sprague Dawley Rat

It is generally accepted that pork fat is harmful to health because of high saturated fatty acid intakes.Stewed pork is rich in fat,the major processing method of stewed pork is long-term stewing.The stewed pork oil is a traditional pork oil processing by stewing.It was reported that long-term intakes of stewed pork benefit for retarding aging,and the resons might be stewing change the fatty acid profile of the stewed pork oil.There are seldom researches about quality changes of pork oil during stewing and effects on physiology.This study based on stewed pork,focused on the quality changes of pork oil during stewing and the effects on physiology of sprague dawley rat,and the molecular mechanism was also discussed.The contents and results of the study as followed:1 Study of quality changes of pork belly during stewingThis study was designed to investigate the effects of different pre-processing method(boiling,boiling + pre-frying)and stewing time(60,90,120,150 or 180 min)on physicochemical and fatty acid characteristicsof stewed pork with induction heating.Proximate chemical composition,texture,sensory evaluation,lipid oxidation,fatty acid profiles and cholesterol content were determined.Based on optimal parameters obtained from induction heating,the stewed pork was processed with flame heating,and the eating quality of stewed pork were compared between two heating medium.The results indicated that prolonged cooking time resulted in higher percentages of dry matter,fat and fat loss in stewed cubes(P<0.01),and the fat loss increased by two pre-processing method;optimal eating quality was showed in 150 min;pre-frying and extended stewing time significantly increased lipid oxidation(P<0.01);cooking modified fatty acid profiles which altered the derived cardiovascular indices,and reduced cholesterol content.In conclusion,long-term stewing may improve the eating quality,composition of fatty acid and cholesterol content,but increase lipid oxidation of stewed pork.The eating quality and fatty acid composition of stewed pork cooked by pre-frying + boiling were better than those of boiling at the same stewing time,while the cholesterol content of stewed pork cooked by pre-frying + boiling was lower than those of boiling.Comprehensive consideration,the optimal paramcter of processing for stewed pork was pre-frying + boiling and stewed 150 min.2 Effects of stewed pork oil on growth and blood composition of aging ratThe purified diets were manufactured according to AIN-93 M with equal stewed pork oil,soybean oil,lard and fish oil respectively.The animal experiment was conduced with twelve-month-old Sprague Dawley rats for 3 month(n = 12 per group).The growth status,feed intakes,average weight gain,liver index,perirenal fat index,epididymis fat index,blood compostion(blood cell and serum biochemical parameter)and insulin resistant index were measured and analized,and to measure the effects of different oil on the growth and blood parameter of rats.The results demonstrated that fish oil might significantly reduce body weight gain and liver index of old rats compared to lard(p<0.05),and no significant difference existed among stewed pork oil,fish oil and soybean oil group(p>0.05).White blood cell count,neutrophile granulocyte ratio,lymphocyte ratio and monocyte ratio of rats significantly reduced in stewed pork oil,fish oil and soybean oil group(p<0.05).Stewed pork oil,fish oil and soybean oil significantly reduced triacylglycerol(TAG)?total cholesterol(TC)?low density lipoprotein cholesterol(LDL-C)in serum compared to lard(p<0.05),however,there was no significant difference of insulin resistance index among each group(p>0.05).Taken together,the results indicated that stewed pork oil,fish oil and soybean oil might differentially decrease body weight gain,level of inflammatory blood cell and TAG?TC?LDL-C of old rats.3 Effects of stewed pork oil on physiology of sprague dawley ratHepatic fat accumulation,oxidative stress,expression of aging related genes and cytokines and absolute telomere length were determined to evaluate the effects of different dietary fats on physiology of sprague dawley rat.The results showed that fish oil significantly reduced hepatic fat accumulation scores of rats compared to lard(P<0.05).and there was no significant difference among stewed pork oil,fish oil and soybean oil group(P>0.05).Stewed pork oil and fish oil significantly increased POD?SOD?GSH-PX?T-AOC but decreased MDA compared to lard(P<0.05).The effects of different oil on aging were differernt.Except 2 significant genes of stewed pork oil group,all significant genes down-regulated compared to lard.The significant genes of stewed pork oil,fish oil and soybean oil were 47,41 and 32 respectively,and the independent expressed genes were 15,15 and 1 respectively.Stewed pork oil,fish oil and soybean oil significantly decreased the gene expression relative to inflammation response,oxidative stress,mitochondrial dysfunction,cell apoptosis,telomere attrition and proteostasis.The enrichment pathways of significant genes were complement and coagulation cascades,oxidative damage,complement activation,classical pathway and toll like receptor signaling pathway.Fish oil and soybean oil significantly decreased relative expression of NF-?B(P<0.05),the expression of IL-1 and TNF-a of fish oil group significantly decreased,and IL-6 of stewed pork oil,fish oil and soybean oil also significantly decreased(P<0.05).The telomere length of fish oil group was significantly higher than lard group,and was no significant difference with stewed pork oil and soybean oil group(P>0.05)?In conclusion,stewing was beneficial for improving quality of pork fat,stewing pork oil might decrease hepatic fat accumulation at certain level,stewing significantly increased antioxidase activities,decreased MDA level,and increased telomere length at certain level.Stewed pork oil might play a role of healthy aging by decreasing oxidative stress and inflammatory response of elderly rats.