乳酸喷淋对猪肉表面减菌效果的研究

Study on bacteria-reducing effect of lactic acid spray on pork surface

为了研究乳酸喷淋浓度、喷淋距离、喷淋量对猪肉表面的减菌效果,进一步优化乳酸喷淋减菌技术,试验以冷鲜猪带皮后腿肉为研究对象,用大肠杆菌、假单胞菌属的恶臭假单胞菌和铜绿假单胞菌、乳酸杆菌配制成浓度为1×10^(7)cfu/mL混合菌悬液预处理10 cm×10 cm×20 cm条状肉样,以菌落总数、大肠杆菌、假单胞菌属、乳酸杆菌的减菌数为检测指标,通过单因素试验,研究乳酸在260 kPa喷淋压力下,采用不同喷淋浓度(1.0%、1.5%、2.0%、2.5%、3.0%)、不同喷淋距离(10 cm、20 cm、30 cm、40 cm、50 cm)和不同喷淋量(50 mL、75 mL、100 mL、125 mL、150 mL)时对混合菌悬液预处理后的肉样的减菌效果;并以菌落总数减菌数为检测指标,通过正交试验对乳酸喷淋参数进行优化和验证。结果表明:随着乳酸喷淋浓度的增加,菌落总数、大肠杆菌、假单胞菌属、乳酸杆菌的减菌数均呈先上升后下降的趋势,其中乳酸喷淋浓度为2.5%时菌落总数和乳酸杆菌减菌数显著高于其他浓度(P<0.05);当乳酸喷淋浓度为2.0%时大肠杆菌减菌数最大,与2.5%差异不显著(P>0.05),但二者均显著高于其他浓度(P<0.05);当乳酸喷淋浓度为2.5%时假单胞菌属减菌数最大,与3.0%差异不显著(P>0.05),但二者均显著高于其他浓度(P<0.05)。随着乳酸喷淋距离的增加,肉样表面菌落总数、大肠杆菌、假单胞菌属、乳酸杆菌的减菌数均呈先上升后下降的趋势,且均为喷淋距离为20 cm时减菌数显著高于其他距离(P<0.05)。随着乳酸喷淋量的增加,肉样表面菌落总数、大肠杆菌、假单胞菌属、乳酸杆菌的减菌数呈持续上升的趋势,当喷淋量为150 mL时菌落总数和假单胞菌属的减菌数最大,与125 mL差异不显著(P>0.05),但二者均显著高于其他喷淋量(P<0.05);当喷淋量为150 mL时的大肠杆菌和乳酸杆菌减菌数均显著高于其他喷淋量(P<0.05)。乳酸喷淋浓度对肉样菌落总数的减菌数影响最大,其次是喷淋量,喷淋距离影响最小。最优乳酸喷淋参数为乳酸喷淋浓度为2.5%、喷淋距离为20 cm、喷淋量为150 mL,此时猪肉表面菌落总数可减少6.90 lg cfu/cm;。说明通过优化乳酸喷淋减菌技术可大大减少猪肉表面初始菌数,有效延长猪肉货架期,可为企业实际生产提供一定的技术指导。

In order to study the effect of lactic acid spraying concentration, spraying distance and spraying amount on the bacteria-reducing effect on pork surface, and to optimize the lactic acid spraying antimicrobial technology, chilled hind leg meat with skin was selected as the experiment subjects, and 10×10×20 cm^(3) strip meat samples were pretreated with 1×10^(7)cfu/mL mixed bacterial suspension prepared by Escherichia coli, Pseudomonas putida, Pseudomonas aeruginosa and Lactobacillus.The total number of bacteria, Escherichia coli count, Pseudomonas spp. count and Lactobacillus count were selected as detection indicators. The bacteria-reducing effects of different spray concentrations(1.0%、1.5%、2.0%、2.5%、3.0%), different spray distances(10 cm、20 cm、30 cm、40 cm、50 cm) and different spray amounts(50 mL、75 mL、100 mL、125 mL、150 mL) of lactic acid on meat samples pretreated by mixed bacterial suspension were studied at 260 kPa spray pressure by single factor test.Decreased bacteria count from the total number of colonies was used as the detection index.The parameters of lactic acid spraying were optimized and verified by orthogonal experiment. The results showed that the reduction number of the total bacteria count, Escherichia coli, Pseudomonas spp. and Lactobacillus increased at first and then decreased with the increase of lactic acid concentration.When the concentration of lactic acid was 2.5%,the reduction number of the total number of colonies and the Lactobacillus was significantly higher than that of other concentrations(P<0.05).The reduction number of Escherichia coli was largest at 2.5% lactic acid spray concentrations, and there was no significant difference between 2.5% and 2.0% lactic acid spray concentrations(P>0.05), but both of them were significantly higher than other concentrations(P<0.05).The reduction number of Pseudomonas spp. was largest at 2.5% lactic acid spray concentrations, and there was no significant difference between 2.5% and 3.0% lactic acid spray concentrations(P>0.05), but both of them were significantly higher than other concentrations(P<0.05).The reduction number of the total bacteria count, Escherichia coli, Pseudomonas spp. and Lactobacilluson meat surface increased at first and then decreased with the increase of lactic acid spraying distance, and the reduction number at the average spraying distance of 20 cm was significantly higher than that at other distances(P<0.05). The reduction number of the total bacteria count, Escherichia coli, Pseudomonas spp. and Lactobacillus increased continuously with the increase of lactic acid spray amount.The reduction number of the total bacteria count, Pseudomonas spp. was largest at 150 mL lactic acid spray amount, and there was no significant difference between 150 mL and 125 mL(P>0.05)spray amounts, but both were significantly higher than other spray amounts(P<0.05).The reduction number of Escherichia coli and Lactobacillus was significantly higher than other spray amounts(P<0.05).The concentration of lactic acid spray had the greatest effect on the reduction number of the total bacteria count, followed by spray amount, and the spray distance had the least effect. The optimal spray parameter of lactic acid were: the lactic acid spray concentration 2.5%, the spray distance 20 cm and the spray amount 150 mL.At this time, the reduction number of the total bacteria count on meat surface was 6.90 lg(cfu/cm~2). The results indicated that the optimized lactic acid spray sterilization technology could greatly reduce the initial amount of bacteria on the pork surface, effectively prolong the shelf life of pork, and provide some technical guidance for the actual production of enterprises.