Studies On Development And Stability Of Brown Probiotics Goat Milk Beverage

The brown probiotic goat milk beverage has the characteristics of refreshing taste,unique flavor,high nutritional value,promoting digestion and absorption of the human intestine.It is as popular as Yakult,Meiyitian,Youyi C and other products on the market.However,This beverage is an acid liquid,and the protein content of goat milk is higher than that of milk.During storage,casein molecules in the beverage tend to aggregate and precipitate under acidic conditions,which results in reduced stability and poor quality of brown probiotics goat milk beverage.In this paper,Maillard reaction conditions,selection of stabilizers,optimization of beverage formula,homogenization conditions and storage characteristics were used to develop brown probiotics goat milk beverage and the stability of the product was studied.The results and conclusions are as follows:1.The effect of Maillard reaction conditions on the quality of brown probiotics goat milk beverage:three reducing sugars（glucose,fructose and fructose syrup）were tested by single factor experiment,and the best reducing sugar was fructose,which was optimized by response surface test.The optimum browning conditions were as follows:fructose 6.50g/100 mL,browning temperature 95℃,browning time 140 min.Under this condition,the beverage has a brown color and strong aromatic flavor with a yellow-blue value of 13.12and a sensory score of 81.7.2.Selectionandcompoundingofstabilizers:pectin,solublesoybean polysaccharicdes,PGA can improve the stability of brown probiotics goat milk beverage in six kinds of stabilizer that includes CMC,Pectin,soluble soybean polysaccharicdes,PGA,xanthan gum and sodium alginate,which were compounded by response surface optimization test.The optimal compounded ratio is PGA 0.11 g/100mL,pectin 0.21g/100mL and soluble soybean polysaccharicdes 0.18 g/100mL.At this condition,the brown probiotics goat milk beverage is in good condition and fresh tastes,the sensory score is 87,the centrifugal precipitation rate is 1.68%,the viscosity is 3.60 MPa,the comprehensive score is 91.45,The relative error with the predicted value is 3.60%,and the combination of the stabilizing agent and the stabilizer is good in fitting degree and can be well applied to the practical production.3.Optimization of the formula of brown probiotics goat milk beverage:the effects of fermented yoghurt,sugar and citric acid on the quality of brown probiotics goat milk beverage were studied by quadratic general rotary unitized design.The optimum formula was:fermented yoghurt（20.00 g/100mL）,sugar（5.00 g/100mL）,citric acid（0.10g/100mL）.The beverage has the characteristics of moderate acidity and sweetness,refreshing taste and unique flavor.The sensory score is 85,the centrifugal sedimentation rate is 2.95%,the viscosity is 3.11 MPa,comprehensive score is 59.08,and the relative error of the predicted value is 0.91%.In conclusion,It can be used in the actual production of brown probiotic goat milk beverage.4.The effect of homogenization on the stability of brown probiotic goat milk beverage:The pH value,viscosity,centrifugal sedimentation rate,stability coefficient,particle size D₄₃3 and sensory evaluation were determined by changing the homogenization temperature and time.The optimum homogenization temperature and pressure was 65℃,20 MPa.The results of variance analysis showed that the effect of homogenization on the stability of brown probiotics goat milk beverage was significant（p<0.05）.5.Study on storage characteristics of brown probiotic goat milk beverage:During the storage period of brown probiotic goat milk beverage,the lactobacilli count decreased from 2.34×10⁹CFU/mL to 1.39×10⁹CFU/mL,the pH value decreased from 3.65 to 3.06,and the viscosity decreased from 3.76 MPa.s to 2.56 MPa.s,the rate of centrifugal precipitation varied greatly,ranging from 1.03%to 3.23%,and the dehydration shrinkage remained at 75.02%to 80.32%.During this period,the brown probiotics goat milk beverage has a uniform tissue state,moderate sweet and sour,refreshing taste and unique flavor.