| Chemical liver injury is caused by chemical hepatotoxic substances,which is mainly caused by cytochrome P450 and N-acetyl-p-benzoquinimide(NAPQI),an intermediate metabolite produced by binding reaction.It is a relatively common liver disease.However,due to its high incidence and side effects of therapeutic drugs,the development of functional food has gradually become a research hotspot.The chicken liver used in this study is one of the main by-products in the process of poultry slaughtering,which is rich in nutrients.However,due to its fishy and bitter flavor,it is difficult to remove and has a high cholesterol content,and high cholesterol is the main cause of cardiovascular and cerebrovascular diseases,which limits the further processing and application of chicken liver.Therefore,reducing the cholesterol content and improving the flavor of chicken liver are the first steps to achieve its industrial use.The purpose of this thesis is to prevent chemical liver injury by fermentation of chicken liver paste with lactic acid bacteria.At present,the health products with liver protection function have gradually entered the international market,so the development and application of this product have a good prospect.In this study,Streptococcus thermophilus STN-26 with better fermentation performance and cholesterol-lowering ability was screened from nine common lactic acid bacteria strains using chicken liver as raw material.Single factor and response surface optimization experiments were used to optimize the fermentation process of chicken liver by lactic acid bacteria.The optimal fermentation conditions were 4% Streptococcus thermophilus inoculum and 6 h fermentation time.The degradation rate of hepatobiliary sterols was 48.17% at 35℃.The fermented chicken liver was processed into chicken liver paste.According to the sensory score,the sensory quality of the pre-cooked chicken liver paste was higher than that of the non-pre-cooked chicken liver paste.At 4℃,20℃,25℃ and other storage temperatures,the Arrhenius equation was used to construct a kinetic prediction model with TVB-N and TBA as the key factors.The relative error between the predicted value and the actual value measured at three storage temperatures with TBA value as the factor was less than 5%,which proved that the model could accurately predict the shelf life of the chicken liver paste at the temperature of 4℃ to 25℃.The fermentation of chicken liver by Streptococcus thermophilus was carried out with the best fermentation process.The changes of basic nutrients in chicken liver before and after fermentation were determined.The results showed that the contents of fat,cholesterol,VA,VE,Ca,Fe,polyunsaturated fatty acids(PUFA),adenine and guanine in chicken liver decreased significantly after fermentation.However,the contents of water,ash,protein,Mg and Zn were decreased,but there was no significant difference.Fermentation significantly increased the contents of VB1,VB2,VB6,VPP,free amino acids(FAA),hydrolyzed amino acids(HAA),Na,saturated fatty acid(SFA),hypoxanthine and xanthine in chicken liver,while the contents of monounsaturated fatty acids(MUFA),K,P,Cu and Se were slightly increased,but there was no significant difference,indicating that fermentation could increase the nutrients and flavor substances in chicken liver.In this paper,acetaminophen(APAP)was used to establish a mouse model of acute chemical liver injury.The ICR mice were randomly divided into blank control group(NC),model group(APAP),low dose(L-CLP),medium dose(M-CLP),high dose(H-CLP)and positive control group(PC)to study the effect of chicken liver paste on acute chemical liver injury induced by APAP in mice.After 15 days of drug administration,Except for the blank control group,acute liver injury model was established by intraperitoneal injection of acetaminophen solution in the other groups.All the mice were sacrificed 24 hours after modeling,and the liver tissues were collected for HE staining to observe the pathological changes of the liver.Western blot(WB)and real-time fluorescent quantitative PCR(RT-q PCR)were used to detect the changes in the expression of corresponding proteins and m RNA in the liver tissue of mice.The results showed that the levels of alanine aminotransferase(ALT),aspartate aminotransferase(AST)and alkaline phosphatase(ALP)in the high-dose group were significantly decreased,and the level of albumin(ALB)was increased,which indicated that the high-dose group had a significant protective effect on mice with chemical liver injury.Therefore,this study mainly discusses the protective effect of chicken liver paste on mice with chemical liver injury from the aspects of anti-inflammatory effect,oxidative stress and apoptosis.The results showed that the high-dose Jegan jam could reduce the inflammatory response in the liver of mice by reducing the inflammatory factors such as tumor necrosis factor-α(TNF-α),interleukin-1β(IL-1β)and interleukin-6(IL-6),and inhibiting the expression of NF-κB-mediated NLRP3/Caspase-1 signaling pathway.It can also increase the activities of antioxidant enzymes such as superoxide dismutase(SOD)and glutathione peroxidase(GSH-PX),reduce the activities of antioxidant enzymes such as malondialdehyde(MDA)and reactive oxygen species(ROS),down-regulate the expression of p22 phox,p40phox,p47 phox and gp91 phox genes in liver tissue,inhibit the activity of NADPH oxidase,and improve the decrease of mitochondrial membrane potential caused by excessive APAP.Activation of Nrf2/HO-1 signaling pathway can inhibit the expression of CYP2E1 and DRP1,thereby alleviating oxidative stress caused by APAP-induced liver injury.Moreover,it can down-regulate the expression of P53 and Bax proteins and up-regulate the expression of Bcl-2protein to alleviate hepatocyte apoptosis.This study improved the processing adaptability of chicken liver,explored the potential industrial added value of chicken liver,verified the protective effect of chicken liver paste on chemical liver injury in mice,and provided a new direction for the food supplement of chemical liver injury. |
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