【作者】 彭健斌；

【导师】 苏平；

【作者基本信息】 浙江大学 ， 食品工程， 2021， 硕士

【摘要】 羊肉作为一种药食两用的优质肉类,肉质鲜美,易于消化吸收,具有良好的营养品质和保健功能,广受消费者的青睐。但目前市面上羊肉深加工制品较少,且相关的研究开发滞后问题日愈凸显。不适的羊肉膻味难以去除,以及羊肉制品产业结构不合理等现象,都严重限制羊肉深加工产业的发展。将羊肉利用发酵技术制作成肉脯,不仅能改善肉脯风味和质地,延长货架期,还可有效去除羊肉膻味,开发出一种新型发酵羊肉脯产品,丰富羊肉制品的种类。本文以发酵羊肉脯为研究对象,探究植物乳杆菌(Lactobacillus plantarum)、肉葡萄球菌(Staphylococcus carnosus)和戊糖片球菌(Pedicoccus pentosaceus)的发酵特性及应用于羊肉发酵的可行性,确定混菌发酵剂的最佳组合,进一步优化羊肉脯的发酵工艺,并通过加速货架期试验考察发酵羊肉脯贮藏品质变化,结合化学动力学方程以建立其货架期预测模型,加以验证。(1)选取植物乳杆菌、肉葡萄球菌和戊糖片球菌研究其发酵特性,结果表明:三株菌种在培养16～18 h后进入生长稳定期,均具有一定的产酸能力,能耐受6%食盐溶液和150mg/L亚硝酸盐溶液;除植物乳杆菌无脂肪酶活性,其他两株菌具有蛋白质和脂肪分解能力,其对膻味脂肪酸的降解率可达60%～80%;各菌均能抑制大肠杆菌和金黄色葡萄球菌生长,且菌种间无拮抗作用,对羊肉制品的风味和形态无其他不良发酵特性;活菌计数结果均为10~9 CFU/m L,三菌基本符合发酵羊肉制品的发酵剂要求,可应用于发酵羊肉制品的生产。(2)利用单一菌种和复配菌种的不同发酵剂组合生产发酵羊肉脯,并比较其品质的差异。与未发酵的羊肉脯相比,羊肉脯经7组发酵剂发酵后,其水分活度、水分含量、p H降低,L*和a*增加,剪切力、硬度和咀嚼性减小,膻味脂肪酸含量显著降低,挥发性风味物质数量和醛类含量明显增多。发酵可以改善羊肉脯的感官品质和安全性,其中混菌发酵对品质的改善效果优于单菌发酵。综合来看,植物乳杆菌、肉葡萄球菌和戊糖片球菌(1:1:1)混合发酵制成的羊肉脯各项指标较好且感官评分最高,可确定其为最佳发酵剂组合。(3)以发酵羊肉脯的感官评分和剪切力为指标,通过单因素和响应面试验优化羊肉脯的发酵工艺,确定最佳的发酵工艺为:发酵剂菌种配比1:1:2(植物乳杆菌:戊糖片球菌:肉糖葡萄球菌),发酵剂接种量2.2×10~7 CFU/g,发酵温度26℃,发酵时间38 h。在此工艺条件下,发酵羊肉脯的剪切力和感官评分别为4989.13和92.2分,相对误差分别为1.05%和1.98%。将以发酵工艺和传统工艺制作的羊肉脯进行比较,发现发酵羊肉脯的营养、感官和质构等各项指标均得到显著改善。(4)根据加速货架期试验结果,发酵羊肉脯在40℃、50℃、60℃下的货架期分别为140 d、112 d和84 d。发酵羊肉脯随贮藏时间的增加,其p H值先减后增,色度值(L*、a*、b*)不断减小,总挥发性盐基氮(total volatile basic nitrogen,TVB-N)含量和硫代巴比妥酸(thiobarbituric acid,TBA)值不断增加,且温度升高会加快品质指标变化速率。Person相关性分析得出TBA值和TVB-N含量是预测货架期的关键指标。利用一级化学动力学方程和Arrhenius方程构建货架期模型,经误差分析和预测能力对比发现,基于TBA值建立的货架期预测模型更适用于预测发酵羊肉脯的货架期,误差在10%以内,以其预测25℃下发酵羊肉脯的货架期为233 d。更多还原

【Abstract】 As a kind of medicinal and edible quality meat,mutton is not only delicious,easy to digest and absorb,but also has good nutritional quality and health care functions,which is widely favored by consumers.However,there are currently few mutton deep-processed products on the market,and the related research and development lagging problem has been highlighted.The unpleasant mutton odor is difficult to remove,and the structure of mutton products is unreasonable,which severely restricts the development of mutton deep processing industry.Using fermentation technology to make mutton into jerky,can not only improve the flavor and texture of jerky,extend the shelf life,but also effectively remove mutton odor.A new type of fermented mutton jerky product has been developed to enrich the types of mutton products.In this study,the fermented mutton jerky was used as the research object.We investigated the fermentation characteristics of Lactobacillus plantarum,Staphylococcus carnosus and Pedicoccus pentosaceus and the feasibility of their application in mutton fermentation.The optimal combination of mixed fermentation starter was determined to further optimize the fermentation process of mutton jerky.The storage quality changes of fermented mutton jerky were investigated by using accelerated shelf-life test,and the shelf-life predicting model was established and verified in combination with chemical kinetic equation.The main research contents and results are as follows:(1)Staphylococcus carnosus,Lactobacillus plantarum and Pedicoccus pentosaceus were selected to study their fermentation characteristics.The results showed that the three strains enter a stable growth period after being cultured for 16～18 h.They had the ability to produce acid and tolerated 6%salt solution and 150 mg/L nitrite solution.Except for Lactobacillus plantarum,which had no lipase activity,the other two strains had protein and fat degradation ability,and their degradation of mutton odor fatty acids reached 60%～80%.They inhibited the growth of Escherichia coli and Staphylococcus aureus,had no antagonism,and had no other negative fermentation characteristics on the flavor and appearance of mutton products.The results of viable bacteria count were all 10~9 CFU/m L.They basically met the starter standard for fermented mutton,and could be applied to the production of fermented mutton products.(2)The different starter combinations of single strain and compound strain were used to produce fermented mutton jerky,and the difference in quality was compared.Compared with unfermented mutton jerky,water activity,water content and p H of mutton jerky decreased after fermented by 7 groups of starters.The L~*and a~*of 7 kinds of fermented mutton jerky were higher than that of unfermented mutton jerky.The shearing force,hardness,chewiness and the content of mutton odor fatty acid of fermented mutton jerky all significantly decreased.The number of volatile flavor substances and the content of aldehydes were significantly increased by fermented.Fermentation improved the sensory quality and safety of mutton jerky,and the quality improvement effect of mixed-strain fermentation was better than that of single-strain fermentation.Taken together,the mixed fermentation of Lactobacillus plantarum,Staphylococcus carnosus and Pedicoccus pentosaceus(1:1:1)produced mutton jerky with better indicators and the highest sensory score,which was determined as the optimal starter combination.(3)The single factor method and response surface test were used to optimize the fermentation process parameters of mutton jerky.The optimal fermentation process were as follows:starter strain ratio(Lactobacillus plantarum:Pedicoccus pentosaceus:Staphylococcus carnosus),1:1:2;starter Inoculation amount,2.2×10~7 CFU/g;fermentation temperature,26℃;fermentation time,38 h.Under such technological condition,the shear force and sensory evaluation of fermented mutton jerky were 4989.13 g and 92.2,and the relative errors were 1.05%and 1.98%,respectively.Comparing the mutton jerky made by fermentation technology and traditional technology,it was found that the nutrition,sensory and texture of fermented mutton jerky have been significantly improved.(4)According to the results of accelerated shelf-life test,the shelf life of fermented mutton jerky at 40℃,50℃and 60℃was 140 days,112 days and 84 days,respectively.With the increase of storage time,the p H value first decreased and then increased,the color value(L*,a*,b*)decreased continuously,and the total volatile basic nitrogen(TVB-N),thiobarbituric acid(TBA)value increased continuously.The increase in temperature accelerated the rate of change of the quality index.Person correlation analysis showed that TBA value and TVB-N content are key indicators for predicting shelf life.The shelf-life model was established by first-order chemical kinetic equation and Arrhenius equation.After error analysis and prediction comparison,it was found that the shelf-life predicting model based on the TBA value is more suitable for predicting the shelf life of fermented mutton jerky,and the relative error is within 10%,which predicted that the shelf life of fermented mutton jerky at 25℃is 233 days.更多还原