Study On The Application Of Sugar Alcohols In Walnut Milk

Walnut milk is a kind of popular milk,whose sweetener is commonly sucrose.However,too much intake of sucrose is easily associated with obesity,cardiovascular,diabetes and other diseases.Therefore,sugar-free walnut milk has become a hot spot in today's researches.Due to similar sweeteness characteristics and low calorific value,sugar alcohol is a good choice for complete or partitial replacement of sucrose in walnut milk.Replacing sucrose completely with xylitol,sorbitol,maltitol and erythritol in walnut milk,this paper studied the thermal stabilities of the four sugar alcohols.The heat stability,emulsifying stability,colour and other qualities of walnut milk added with sugar alcohols and sucrose were compared before and after sterilization.Finally,the shelf life of walnut milk sweetened with poloys and sucrose was predicted by accelerated storage test.The main contents and conclusions were as follows:First,a quantative method of xylitol,sorbitol,maltitol and erythritol was established.Then the thermal stabilities of four sugar alcohols under 115°C,118°C,121°C sterilization conditions were analyzed.HPLC was adopted for quantative analysis.A TOSOH Amide-80 column(2.0 mm?15 cm,3 ?m)kept at 26°C eluted with acetonitrile and water was used for separation.The detector adopted was evaporative light scattering detection whose evaporative temprature was 50°C,the flow rate of air was 2.5 L/min.The results showed that the linear range of erythritol and xylitol was 0.15~1.25 mg/m L,and the linear range of sorbitol and maltitol was 0.05~1.45 mg/m L.The precision of the HPLC-ELSD method was <3.5% in 6 replicate determinations,and average spike recovery was 94.3~102.8%.The remaining percentages of four sugar alcohols indicated that stability increased with pH in the range of pH 6.0~8.5 and decreased with temperature,and four sugar alcohols were all suitable for the application of alkaline walnut milk.At the three sterilization temperatures,the remaining rate of the four sugar alcohols was 83.03~101.76%,and the stability condition of sugar alcohols was xylitol > maltitol > erythritol > sorbitol.And the appropriate sterilizing time of the four poloys at 121°C,118°C,and 115°C was respectively controlled within 20 min,20 min and 25 min.Second,the optimum sterilization conditions of walnut milk were studied.The optimum F values of walnut milk sweetened with sucrose,maltitol,sorbitol,erythritol and xylitol were 4.0 min,3.4 min,3.0 min,3.4 min,3.4 min respectively.Compared with 115°C and 118°C,the stability,sensory quality and colour of the production processed at 121°C were superior at the same F value.Therefore,the optimum sterilization temperature of walnut milk added with sucrose,maltitol,erythritol,sorbitol,xylitol was 121°C,the time was respectively 14.8 min,13.3 min,13.9 min,13.2 min and 13.8 min,and the substitution of maltitol,erythritol,sorbitol,xylitol can reduce sterilization time by 10.14%,6.08%,10.81%,6.76%.Then,the quality variation of walnut milk sweetenend with four sugar alcohols and sucrose before and after sterilization was on research.Before sterilization,the stability,viscosity,absolute value of Zeta potential,turbidity and interfacial tension of walnut milk added with sugar alcohols were all decreased compared with sucrose group.The replacement of xylitol,sorbitol,erythritol improved the protein solubility,but the substitution of maltitol had no significant difference.Compared with sucrose group,the average particle size of walnut milk added with xylitol,sorbitol,erythritol was reduced,while the particle size of maltitol group had no significant difference.Maltitol prolonged the heating coagulation time,but sorbitol,erythritol,xylitol shortened the time,which suggested that maltitol was more able to improve the thermal stability of walnut milk than sucrose,while the other sugar alcohols relatively reduced it.After sterilization,the thermal residual rates of maltitol,xylitol,erythritol and sorbitol in walnut milk were 95.78%,95.73%,95.12% and 94.91% respectively,and the thermal stabilities were good;Sorbitol,maltitol,xylitol and erythritol enhanced the stability,sensory quality and protein solubility of walnut milk due to shorter sterilization time.In a word,the quality of walnut milk added with sorbitol,xylitol,maltitol and erythritol was superior to that of walnut milk sweetened with sucrose.Finally,the variation of sensory difference,average particle size,centrifugal precipitation rate and viscosity of walnut milk stored at 25°C,35°C and 45°C were studied by accelerated test.The centrifugal precipitation rate and sensory difference were used as indicators to predict the shelf life under room temperature.The shelf life of walnut milk sweetened with maltitol,erythritol,sorbitol,xylitol and sucrose was 219 d,192 d,216 d,209 d,187 d,respectively.Therefore,the alternative of maltitol,erythritol,sorbitol and xylitol can extend the shelf life of walnut milk by 17.11%,2.67%,15.51%,11.76%.The calculated results showed that the caloric value of walnut milk sweetened with maltitol,sorbitol,erythritol and xylitol was 23.08%,15.38%,48.42% and 19.46% lower than that of walnut milk added with sucrose.All in all,through overall consideration of thermal stability of sugar alcohol,the quality and shelf life of walnut milk,maltitol was the best choice for applying in the walnut milk to replace sucrose among four polyols,and sorbitol and xylitol respectively took the second and third place.The substituting effect of erythritol was worse than that of other sugar alcohols,but it's still a good choice to replace sucrose owning to the lowest caloric value.