| The present study aims to elucidate the main factors influencing the formation of N-nitrosamines(NAs)in western bacon and the blocking of N-nitrosamine.The effects of species of raw meat,fat proportion and processing technology on the formation of N-nitrosamine were evaluated.The efficiency of different levels of nitrification inhibitors in blocking the formation of NAs was determined.Base on the above analysis,the new western bacon products with low contents of N-nitrosamines were manufactured and evaluated for its quality during freeze and thaw cycles.The main results are as follows:(1)The effects of several potential factors on the formation of NAs including: source of raw meat(from ternary hybrid white pig hereinafter referred to as white pork,meat from white pig fed Chinese herbs,black pork),parts of the carcass(lean,fat,mixture of lean and fat),pickling time(0 h,12 h,24 h),smoking time(2 h,4 h,6 h,8 h),frying time(2min at 180?)were analyzed.The contents of residual nitrite,8 biogenic amines(BA)and9 NAs and other related indicators were detected.The results showed that: western bacon manufactured with white pork had lower contents of nitrite,biogenic amines and N-nitrosamine than those with black pork(P<0.05).The content of N-nitrosamines in the mixture of fat and lean was significantly higher than that in pure fat and lean(P<0.05);The formation of N-nitrosamines and biogenic amines occurred mainly during smoking and frying.(2)Microbial nitrification inhibitors(MNI)prepared according to our previous research adding to pickling solution as 0%,0.05%,0.10%,0.15%,0.20%,0.25%,0.50%(based on weight of bacon)to manufacture 7 groups of bacon,where the contents of nitrite,N-nitrosamine,and biogenic amines were determined.The results showed that with the increase of MNI(0.1%~0.15%),the eliminating rate of nitrite increased significantly,the blocking of N-nitrosamines and biogenic amines enhanced firstly but then weakened.The optimal MNI was 0.1%~0.2% according to the comprehensive evaluation of the above indicators.(3)Two composite antioxidants(CA)that selected previously in a stimulatory system where CAI containing tea polyphenol,rosemary,VE and VC and CAII containing VC,grape seed extract,niacinamide and coenzyme Q10 were added to bacon.The eliminating effectof CAI and CAII on N-nitrosamine,nitrite,biogenic amines were subsequently studied.The results showed that the content of nitrite,biogenic amine and N-nitrosamine bacon adding with CAI was significantly lower than that with CAII(P<0.05)where the inhibition rate of N-nitrosamines was 35.46% higher than CAII;The two composite antioxidants have different inhibitory efficiency depending on the species of N-nitrosamines where CAI was more efficient on inhibition of NDMA?NMEA?NDPA?NPIP,and CAII was more efficient on inhibition of NPYR.(4)According to the results of(2)and(3),sliced bacon with no N-nitrosamine inhibitors(control,CK)and with an additional 0.15% MNI and CAI were made,vacuum-packed.The 70 days of storage contained ten times of freeze and thaw cycles where samples stored in-18? were thawed under tap water to reach a central temperature of 2~4 ? every 10 days,at the 0,1,3,7,10 cycle,the three groups of bacon were sampled to evaluate the sensory quality,the total microbial count,shear force,color difference,TVB-N,TBARS,p H and the content of nitrite,biogenic amine and N-nitrosamine.The results showed that TVB-N,TBARS,NAs,BA and the total microbial count increased with the increase of freeze and thaw cycles,while the shear force,values of L* & a* and contents of nitrite decreased representing a deterioration of sensory quality.Compared with the three groups,bacon containing MNI and CAI deteriorated more gently than the control group,especially the formation of NDMA were significantly slower than control,which was lower than the limitation of Chinese Standard of 3 ?g/kg.The inhibitory of MNI and CAI on NDMA was 65.1% and 33.0%,respectively.The results proved that MNI and CAI could improve the safety of western bacon. |
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