山楂果胶低聚半乳糖醛酸(PGA)酸奶饮料工艺优化及PGA对乳酸菌的抑制作用

以山楂超微果粉和牛乳为主要原料,添加果胶低聚半乳糖醛酸(pectin oligogalacturonic acid,PGA),制作山楂PGA酸奶饮料。运用正交实验对山楂PGA酸奶饮料进行工艺条件优化并通过测定菌液OD值研究乳酸菌在此工艺下的生长状态。结果表明,最佳工艺条件为:杀菌后牛乳加入7%的蔗糖、2%山楂超微果粉、0.25%的乳酸菌菌粉,42 ℃发酵5 h后加入2‰半乳糖醛酸,低温后熟。在此条件下得到的酸奶组织结构光滑细腻,质地均匀,酸甜适中,具有浓郁的酸奶风味。乳酸菌抑菌实验表明,制备的寡聚半乳糖醛酸混合物在添加量2‰时,抑制率达23.6%。酸奶在30 ℃的贮藏环境下可有效延长2 d(7 d贮存期内)的货架期,并保持乳酸菌活性。

Process Optimization of Hawthorn Pectin Oligogalacturonic Acid (PGA) Yogurt Drinks and Inhibitory Effect on Lactic Acid Bacteria by PGA

Hawthorn berry ultrafine powder and milk were used as the main ingredients together with pectin oligogalacturonic acid(PGA)to produce hawthorn PGA yogurt drinks. Orthogonal test was used to optimize the technological conditions of hawthorn PGA yoghurt beverage and the growth state of lactic acid bacteria under this technology was studied by measuring the OD value of bacterial liquid. The results showed that the optimum technological conditions were as follows:Milk sterilization followed by the addition of 7% sucrose solution,addition of 2% hawthorn berry ultrafine powder,addition of 0.25% lactic acid bacteria powder,fermented 5 h under 42 ℃ addition of 2‰ galacturonic acid,and finally post-ripened at a low temperature. Under these process conditions,the texture of the yogurt drink product was uniform,fine,and smooth. The drink had a balanced taste between sourness and sweetness,and a rich yogurt flavor. The experiment on the inhibition of lactic acid bacteria showed that when the PGA mixture added was at 2‰,the inhibition rate was 23.6%. The shelf life of yogurt could effectively be prolonged for 2 d(within the 7-day storage period)and the activity of lactic acid bacteria could be maintained under the storage environment of 30 ℃.