乳脂乳球菌复配发酵乳贮藏期品质变化研究

Changes of the quality of fermented milk with Lactococcus lactis ssp.cremoris during storage

探讨了分离自新疆酸奶疙瘩的一株乳脂乳球菌,在乳制品应用中具有的潜在益生价值。通过测定多肽、滴定酸度、丁二酮、乙醛、黏度、活菌数等指标,研究了乳脂乳球菌复配菌株发酵乳在贮藏期间的发酵特性。结果表明,在贮藏期发酵乳各指标均显著高于对照组,酸度升高了29.59°T,后酸化能力较强。丁二酮含量在整个贮藏过程中较稳定,乙醛、多肽、黏度、胞外多糖的含量在贮藏7 d后达到最大值。多肽含量最高达3.34 mg/m L,胞外多糖含量与测定的黏度值呈现正相关。活菌数呈下降趋势,贮藏21 d后,为7.8×107CFU/m L,仍高于发酵乳标准中活菌数1×106 CFU/m L的要求。

The potential application in milk products ofLactococcus lactis ssp. cremoris isolated from Xinjiang yogurt bumps was discussed. The fer- mentation characteristics of compound strains fermented milk of Lactococcus lactis ssp. cremoris during storage were researched via the determina- tion of polypeptide, titration acidity, butanedione, acetaldehyde, viscosity, viable count and so on. The results showed that each index of fermented milk was significant higher than the control group, the acidity increased 29.59 °T, and the capacity of post-acidification was strong. The butanedione content remained stable during the whole storage, the contents of acetaldehyde, polypeptide, extracellular polysaccharide and viscosity reached to the maximum after 7 d. The maximum content ofpolypeptide was up to 3.34 mg/ml. The extracellular polysaccharide content was positively related with viscosity. The viable count was on a declining trend, and it was up to 7.8×107 CFU/ml after storage for 21 d, but it was still higher than the viable count （1 × 106 CFU/ml） in the National Standard.