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℃.