Effects Of Microorganisms On The Characteristics Of Air-Dried Beef Products

Air-dried beef is a traditional cured beef product in China.It is easy to process,store and transport.It is popular among the public because of its convenient consumption,nutrient-rich and unique flavor.However,the traditional wind beef production is naturally dried under low temperature conditions,which is not only limited by geographical,climatic and seasonal conditions,but also the uncontrollable processing environment increases the risk of pollution of harmful microorganisms,nitramine and benzopyrene.The quality and safety of cured fermented meat products have also been highly concerned by self-controlled air drying processes and artificially added microbial starters.To this end,the microbial starter regulation technology of air-dried beef under controlled air-dried fermentation conditions was studied.The focus was on the microbial flora in commercial starter and the beneficial bacteria in traditional natural bean seasoning.The effects of physicochemical,free amino acids and volatile flavor substances lead to the following findings:1.Perform self-control imitation natural air drying instead of natural air drying process and technical parameters screening and determination.The air-dried beef is made by traditional natural air drying,hot air baking and drying and natural self-control air drying.The product characteristics are analyzed and compared,and the comprehensive evaluation of the controllability of the processing environment,processing cycle,processing efficiency and safety.The results show that the natural self-control drying can not only retain the flavor of the product to the maximum extent,but also effectively prevent the fat oxidation of the beef product,solve the problem of slow natural drying speed,low production efficiency,and easy oiling and excessive oxidation of hot air drying and drying products.It can also improve the safety of products and achieve standardization and industrial production of products.After single factor experiment,the process and main technical parameters of self-control drying to produce air-dried beef were determined as follows: raw material selection?cutting?mixing?rolling(4~6°C,2h)? pickling(2~4°C,24h)? Fermentation air drying(temperature 6~10 °C,humidity 55~60%,wind speed 1.5~2.0m/s,time11~12d)?hanging(24~30h),the product dehydration rate is 40~45%.2.Screening of direct-fermented fermenting microorganisms and natural fermenting microorganisms for air-dried beef processing.First,choose from commercial fermented microbial strains(direct-injection freeze-dried bacteria),compare the physical and chemical properties,microbial characteristics,flavor characteristics of the dried beef,and sensory indicators that adapt to Chinese consumption habits.The No.5 fermenting strain of(Staphylococcus carnosus,Pediococcus pentosaceus and Debaromyces hansenii)combines Chinese sensory habits and further guarantees while improving the sensory and physical andchemical properties of the product.The storability and hygienic safety of the product enhance the quality of the product.Using this strain to process air-dried beef,the main characteristics of the product are: sensory total score of 8 points,pH value of 6.15,aw value of 0.761,volatile base nitrogen(TVB-N)14.69 mg/100 g,nitrite residue 3.46 mg/kg,total colony 8.23Log(CFU/g),lactic acid bacteria 6.04 Log(CFU/g),coliform bacteria and pathogenic bacteria were not detected,total free amino acid was 42.12 g/100 g,volatile flavor detected substance The relative total content is 89.22%.Further,the natural bean seasonings(bean meal,watercress,bean curd,soy sauce)rich in beneficial bacteria are analyzed for microbial characteristics,and the seasonings with more abundant microbial species,more content,and closer to the fermenting microbial flora are selected as air-dried.A source of raw materials for naturally fermented microorganisms in beef production.The results showed that the structure and microbial composition of the watercress group in Pixian County were more suitable for adding to the dried beef,and it was the most commonly used seasoning in Sichuan meat products.The source was stable,and the main flora structure and content were Lactic acid bacteria.5.13 Log(CFU/g),Moulds 3.06 Log(CFU/g),Yeasts 3.29 Log(CFU/g),Microbes4.83 Log(CFU/g).3.Study on the effects of fermenting microorganisms on the sensory,conventional physical and chemical properties and texture characteristics of air-dried beef.Three groups of air-dried beef were prepared by natural-controlled air-drying process,and direct-fermented fermenting microorganisms(group A)and Pixian bean peas were added as natural fermenting microorganisms(group B),and traditional air-dried beef without adding fermented microorganisms(group C).Compare.The results showed that there was no significant difference between the total sensory scores and water activity values of the three groups(p>0.05);the chromaticity values were significantly different among the groups(p<0.05):redness values(C<B<A),yellowness value(A<B<C);pH value was significantly different between groups(p<0.05):(A<B<C);moisture content value,There was no significant difference between the two groups(P>0.05).There were significant differences between the two groups(P<0.05):(B<C,A<C);crude protein There were significant differences in crude fat content between the groups(p<0.05):(B<A<C);nitrite residues were significantly different between groups(p<0.05):(A<C<B);texture characteristics were significantly different between groups(p<0.05): hardness(A<B<C),chewiness(A<B<C),firmness(A<C<B).The results showed that the direct-fermented fermenting microorganisms can significantly improve the fermented color of air-dried beef,improve the texture characteristics such as hardness and chewiness of air-dried beef,reduce pH,TVB-N value and nitrite residue,and improve product quality and safety.Naturally fermented microorganisms have also been shown to improve product quality and enhance product color stability and safety.However,direct-fermented fermenting microorganisms are more effective in improving the quality and safety of air-dried beef products than natural fermenting microorganisms.4.Study on the effect of fermenting microorganisms on total free amino acid content in air-dried beef products.A total of free amino acid content,including total free amino acids(TAA),was obtained by using an amino acid analyzer for three groups of air-dried beef products(direct-fermentation fermenting microorganism group A,Pixian watercress natural fermenting microorganism group B,and traditional air-dried beef group C).),essential amino acids(EAA),non-essential amino acids(NEAA),umami amino acid(DAA)content,and umami amino acid ratio(DAA/TAA),essential amino acid ratio(EAA/TAA),etc.Compared with group C,the content of TAA increased by 3.60g/100 g,the content of EAA increased by2.63g/100 g,the content of DAA increased by 5.46g/100 g,the DAA/TAA increased by 9.34%,and the EAA/TAA increased by 3.12%.Group C: TAA content decreased by 3.55g/100 g,EAA content increased by 0.11g/100 g,DAA content increased by 0.29g/100 g,DAA/TAA increased by 5.38%,and EAA/TAA increased by 4.15%.The results showed that the direct-fermentation fermenting microorganisms and natural fermenting microorganisms had significant effects on the improvement of air-dried beef DAA/TAA and EAA/TAA.Compared with natural fermenting microorganisms,direct-injection fermenting microorganisms for air-dried beef TAA,DAA and DAA /TAA's lifting effect is more significant and better.The effect of fermenting microorganisms on the content of volatile flavor substances in air-dried beef was studied.Firstly,the four key factors affecting the extraction effect of air-dried beef(extraction needle,extraction time,extraction temperature,sample desorption time)were optimized by response surface method to obtain the best extraction conditions:50/30?m extraction head DVB/CAR/PDMS Model,extraction temperature 67? extraction time 33 min,sample desorption time 4 min.Under the optimal extraction conditions,three groups of air-dried beef(direct-fermentation microbial group A)were tested by headspace solid phase microextraction-gas chromatography-mass spectrometry(HS-SPME-GC-MS).The type and relative content of volatile flavor substances in the natural fermented microbial group B of the county,and the traditional air-dried beef group C.The results showed that compared with group C,there were 14 kinds of volatile flavor substances detected in group A,and the relative content increased by 13.92%.Compared with group C,one group of volatile flavor substances was detected,and the relative content increased.7.82%.Direct-injection fermenting microorganisms and natural fermenting microorganisms are beneficial to the improvement of volatile flavor substances and total peak area of air-dried beef.Among them,direct-injection fermenting microorganisms have greater influence on air-dried beef volatile wind substances than natural fermenting microorganisms.Compared with natural fermentingmicroorganisms,the direct-injection fermentation microorganisms have extremely better effects and stronger effects.