Study On The Effect Of Fermented Milk With Streptococcus Thermophilus On Foaming Properties Of Egg Liquid And Sponge Cake Quality

This paper discussed the fermentation properties in skim reconstituted milk about five strains of Streptococcus thermophilus and ST5-8h,ST5-24 h and ST9-24 h fermented milk were added to the whole egg liquid respectively.It aimed at investigating the effect of fermented milk on the foaming ability and foam stability of liquid whole egg and application in the sponge cake by measuring nature of the mixture.The results were as follows:The acidification and viscosity production between 5 strains of Streptococcus thermophilus after fermented 8 hours and 24 hours in skimmed milk were difference.By comprehensive comparison,two strains(ST5 and ST9)were chosen to study more in the fermentation process of 60 hours.It was showed that the ST5 fermented milk obtained the highest acidity and viscosity at different fermentation time,the content of reducing sugar and total sugar was lower.While ST9 fermented milk was in the opposite and capacity to degrade proteins was stronger.The ST5-8h,ST5-24 h and ST9-24 h fermented milk were added respectively to the liquid whole egg and the mixture properties of pH,Zeta potential,viscosity,surface tension,the change of microstructure,etc were measured.Increasing fermented milk concentration 0%-50%(w/w)gradually decreased pH values and changed surface tension and the solution viscosity presented an increase.Compared with skim milk powder and 10% skimmed milk solution with same protein content,the fermented milk had a significant impact on the bubbles elasticity and could slow down the drainage rate in the foams.In conclusion,fermented milk could improve the foam stability of liquid whole egg and had little impact on the foaming ability.According to the effect of fermented milk on foaming properties about liquid whole egg,ST5-8h、ST9-24 h fermented milk and 10% skimmed milk solution were chosen to make sponge cake.The properties about density of cakes batter,cake volume,moisture content,texture parameters and sensory evaluation were analyzed.Compared with the control group,the addition of fermented milk could significantly reduce the density of sponge cake batter and smaller with the increase of the contention,that is greater amount of air in the batter.At the same time,sponge cakes with fermented milk had higher moisture content and it would still maintain above 20% after 3 days storage in a refrigerator.Then the cake flavor,color,volume and nutritional value could be improved with moderate amount of ST5-8h and ST9-24 h fermented milk.