Study On Application Of Lactobacillus With Antiseptic And Antioxidant Effect In Fermented Sausage

In this study,lactic acid bacteria(LAB)were isolated and screened from Yanji pickles,homemade sauerkraut and Sichuan pickles according to the screening criteria for fermented sausage starters.Among all the screened LAB,the best bacteria W36 was identified as Pediococcus pentosaceus.Together with other four LAB strains obtained from our laboratory,the five strains were screened for their potential application as fermented sausage starter.Then the fermentation and cooking parameters,formula composition,quality and storage characteristics of fermented sausage were further studied in this paper.Results were as follows:1.Isolation,screening and identification of LAB and preferred tests for fermented sausage strains.1)A total of 36 LAB strains were screened from samples,which can grow on the MRS medium and produce clear calcium rings,no spores,Gram-positive and catalase-negative strains.At the same time,according to the standards of fermented sausage starter,there was only one strain W36 that met the criteria.The strain W36 was identified as Pediococcus pentosaceus by morphology,physiology,biochemistry and 16S rDNA molecular biology.2)Two strains(P.pentosaceus and Weissella hellenica)with antioxidant ability,with three strains(Lactobacillus sakei,Greece Wesellaella hellenica and Enterococcus faecalis)with bacteriocin-producing ability were explored for salt tolerance,nitrite resistance,strain 24 h growth ability,strain antagonism and strain combination determination test.Determination of fermented sausage starter strains:W.hellenica with antioxidant capacity and two bacteriocin-producing L.sakei and P.pentosaceus strains were picked out for further study.2.Determination of fermentation and cooking parameters,formula composition of fermented sausages.1)Optimizition of fermentation process:the strain inoculation amount is 10~7 cfu/g,and the strain ratio(Wh:Ls:Pp)is 2:1:1.The humidity is 90%and the fermentation time is 18 h.2)Optimizition of fermented sausages formula by response surface method:salt 1.60%,glucose 0.50%,carrageenan 0.3%,and white pepper 0.50%.3)Optimizition of cooking process by response surface method:cooking temperature 40°C,smoking time 150 min,baking time 30 min,baking temperature 45°C.3.Research on the quality characteristics test of fermented sausages.1)The microstructure of fermented sausages was studied by scanning electron microscopy.The results showed that the surface of the myofibrils of the fermented sausages was smooth in the control group(non-inoculated starter),and the myofibrils were rectangular or square.And the myofibrils were arranged relatively neatly.The experimental group(inoculated with starter)had rougher surface of myofibrils,and myofibrils showed round spheroidal particles.Furthermore,myofibrils arranged loosely,indicating that the addition of starter could improve tenderness and quality of fermented sausages.2)Gas chromatography was used to study the free fatty acids in fermented sausages.The results showed that eight kinds of free fatty acids were detected in the control group of fermented sausages,nine kinds of free fatty acids were detected in the experimental group,and the percentage of free fatty acids in the experimental group was measured increasing.The addition of the starter stimulated the endogenous or microbial lipase activity so that the free fatty acids in the fermented sausage were released in large quantities.3)The automatic amino acid analyzer was used to study the free amino acids of fermented sausages.The results showed that the free amino acids in the control group and experimental group were mainly leucine,followed by cysteine,phenylalanine and valine;they accounted for47%of total free amino acids.Compared with the control group,the fermented sausage in the experimental group had higher free amino acid content,indicating that the starter played a role in the decomposition of the protein,which has an important role in the formation of the flavor of the fermented sausage.4)Gas chromatography-mass spectrometry was used to study the volatile flavor compounds of fermented sausages.The results showed that 82 flavor compounds were detected in the control group of fermented sausages,and 92 flavor compounds were detected in the experimental group of fermented sausages.These volatile components were mainly hydrocarbons,alcohols,esters,aldehydes,acids,quinones,ketones and aromatics.Of which 5are alcohols,5 are aldehydes,1 is acid,and 4 ketones increased.One species and four aromatic species were added,indicating that the starter had a very significant effect on the improvement of the flavor of fermented sausages.4.Study on Storage Test of Fermented Sausages.1)Sensory indicators of fermented sausages.During the storage process,the sensory scores of the two groups of fermented sausages changed significantly with the extension of time.The radar chart of the control group was slightly uneven,whereas the experimental group did not change obviously.2)Physical and chemical indicators of fermented sausages.During the storage process,the pH values of the two groups of fermented sausages decreased first and then increased.The changes in the control group were not unstable.The chroma and texture indicators of the experimental group were more stable than the control group;The water content and water activity in the experimental group were lower than those in the control group.The nitrite residues in the fermented sausages of both groups were lower than 30 mg/kg(national standard).The TBA value,TVB-N value,and POV value of the experiment group were all lower than the control groups.All the values obtained in this paper meet the national standard.3)Microbiological indicators of fermented sausages.The number of the total number of bacteria in the two groups rose first and then decreased.Finally,the state of balance was maintained and the experimental group was more stable than the control group.After storage for30-60 d,the number of E.Coli in control and experimental group was less than 3.0 MPN/g;and when stored for 90 days,E.Coli of the control group was more than 3.0 MPN/g,and the sausages were degraded.When the fermented sausages in the experimental group were stored for 30 to 100 days,the results showed that the E.Coli were less than 3.0 MPN/g.The sausages deteriorated when stored for 110 days,since the number of E.Coli was more than 3.0 MPN/g.