Study On The Effect Of Sodium Nitrite On The Quality Of Dry-Cured Fermented Sausages

During processing and storage,dry-cured meat products are prone to oxidation,affecting the hydrolysis process during fermentation and the production of small molecule active substances.These factors are closely related to the final nutritional quality,flavor attributes,and health activity of the product.Sodium nitrite,a common additive,is used to improve the quality of cured meat products.At present,the maximum addition limit for nitrite in meat products at home and abroad is mostly 150mg/kg.Although it is recognized that excessive use of nitrite poses a cancer risk,its role in meat products at safe doses is still difficult to replace.Existing research has shown that sodium nitrite has an inhibitory effect on fat oxidation in meat products.However,the comprehensive effect of adding sodium nitrite on various components in dry-cured meat products,such as protein oxidation and hydrolysis,especially the impact on the production of bioactive substances（such as bioactive peptides）,is still unclear.This study uses beef with high myoglobin content and chicken with low myoglobin content as typical animal products to analyze the inhibitory mechanism of sodium nitrite on myoglobin-mediated lipid oxidation through the preparation of minced meat models.By preparing dry-cured fermented sausages and combining peptidomics and proteomics,the effects of adding sodium nitrite on protein oxidation,protein hydrolysis,and bioactive peptides in dry-cured fermented sausages are investigated,and the comprehensive effects on oxidative/hydrolytic products are explored.In combination with in vitro simulated digestion experiments,the effects of sodium nitrite（≤150 mg/kg）on lipid and protein oxidation processes in the gastrointestinal tract are evaluated.This study aims to provide a scientific basis for optimizing the quality of dry-cured fermented sausages.The specific research results are as follows:The addition of NaNO₂significantly inhibited the lipid oxidation induced by myoglobin（Mb）.Mb significantly promoted lipid oxidation in beef,with the TBARS value increasing from 5μmol/kg to 25μmol/kg,while the TBARS value remained within 10μmol/kg after adding NaNO₂,indicating that lipid oxidation was inhibited;the addition of NaNO₂inhibited the degradation of protoheme content in beef（>33μmol/kg）and the increase of non-heme iron content（about 65%）,and significantly reduced H₂O₂content;electron spin resonance spectroscopy results showed that the addition of NaNO₂reduced the lipid free radical content;UV-visible spectroscopy results indicated that NaNO₂formed a stable NO-Mb structure with Mb,thus NaNO₂reduced the degradation of protoheme IX in Mb and inhibited the release of iron ions in myoglobin,slowing down Mb-mediated lipid oxidation in beef.The addition of NaNO₂inhibited lipid and protein oxidation in beef and chicken dry fermented sausages,reduced protein aggregation caused by oxidation,and promoted protein hydrolysis.NaNO₂significantly reduced the TBARS and PV values in beef and chicken sausages（p<0.05）,inhibiting sausage lipid oxidation;compared with the non-added group,the protein carbonyl content and surface hydrophobicity in sausages with added NaNO₂were significantly reduced（p<0.05）,indicating that NaNO₂inhibited protein oxidation in sausages;protein solubility in beef and chicken sausages with added NaNO₂was about 10%higher than that of the non-added group at the end of storage,free amino acid levels were significantly increased（p<0.05）,and the low molecular weight band area in the protein electrophoresis pattern was deepened,indicating that NaNO₂reduced protein aggregation,increased protein solubility,and promoted its hydrolysis.The addition of NaNO₂increased the concentration of peptides and antioxidant activity in beef and chicken dry fermented sausages,and increased the variety of antioxidant peptides in the sausages.With the extension of processing time,the peptide concentration in beef and chicken dry fermented sausages increased from 3.6mg/m L and 3.0 mg/m L to 5.8 mg/m L and 5.3 mg/m L,respectively.The addition of NaNO₂increased the peptide concentration by about 10%and significantly increased the in vitro antioxidant activity of peptides（DPPH,ABTS,hydroxyl radicals,and superoxide anion radical scavenging capacity）（p<0.05）.In beef dry fermented sausages,a total of 123 types of peptides were identified,mainly derived from myoglobin（44.56%）,myosin（14.39%）,and actin（15.59%）.New antioxidant peptides,namely GLAGA,LPGGGT,and AEEEYPDL,were identified in sausages with added NaNO₂at the end of processing,and the variety of antioxidant peptides in the sausages increased significantly after the addition of NaNO₂.NaNO₂is closely related to the hydrolysis of proteins and fatty acids.It increases the variety of proteins and amino acid content in sausages,affecting the composition of volatile components and final sensory quality.After adding NaNO₂,the number of protein types in chicken dry fermented sausages increased from 924 to 1037,and the number of protein types in beef sausages increased from 860 to 870.Proteomics analysis showed that the addition of NaNO₂affected protein complex assembly,lipid localization regulation,eicosanoid biosynthesis,protein serine/threonine phosphatase activity,and enzymes acting on ester bonds.NaNO₂significantly increased the content of various amino acids（p<0.05）and significantly reduced the content of hexanal,hexanol,andβ-pinene in sausages.The overall odor,sourness,aroma,and overall flavor of the sausages were higher than the control group without NaNO₂.The addition of NaNO₂inhibited lipid and protein oxidation in beef and chicken dry fermented sausages during in vitro gastrointestinal digestion but increased the level of nitrosamines.As the amount of NaNO₂added increased,the TBARS value of sausages during in vitro simulated digestion was significantly inhibited,delaying lipid oxidation in the in vitro gastrointestinal tract.Medium and high doses of NaNO₂（100mg/kg and 150 mg/kg）delayed the increase in protein carbonyl content,inhibiting protein oxidation during in vitro digestion.The addition of NaNO₂increased the level of nitrosamines;in beef sausages with 150 mg/kg NaNO₂,the nitrosamine content increased from an initial 90μmol/kg to 130μmol/kg after simulated small intestine digestion.In summary,NaNO₂can form a stable NO-Mb structure with Mb,inhibiting Mb-mediated lipid oxidation in beef;NaNO₂can inhibit protein oxidation in dry fermented sausages,reduce protein aggregation caused by oxidation,and promote protein hydrolysis;this in turn increases the peptide content in fermented sausages and produces antioxidant peptides with certain biological activities.NaNO₂is closely related to the degradation of proteins and lipids,increasing the content of small molecule amino acids and reducing some volatile lipid components,improving product sensory quality.Additionally,NaNO₂can inhibit lipid and protein oxidation in dry fermented sausages during in vitro gastrointestinal digestion.This study provides theoretical basis for the application,control,and safety of sodium nitrite in the production of fermented meat products,and provides theoretical support for the research and production of functional fermented meat products.