亲水胶体对糖溶液模拟冷冻过程中冰晶生长的影响

Effects of hydrocolloids on the growth of ice crystals in simulated freezing of sugar solutions

为了探讨冰淇淋等冷冻甜品溶液的流变性对冷冻成品中冰晶生长的影响,配制0.3%(质量分数)的不同亲水胶体(黄原胶、罗望子胶、瓜尔豆胶、羧甲基纤维素和刺槐豆胶)的糖溶液,通过依次降低糖溶液中0%、15%、30%、45%、60%和75%的水含量模拟冷品冷冻过程,分别采用流变和低温显微镜技术研究溶液的黏弹性与重结晶速率的关系。结果表明,与不含亲水胶体的对照组比较,含不同亲水胶体的糖溶液的流变性对重结晶速率具有显著性影响,其中,罗望子胶对重结晶速率影响最为显著,使得重结晶速率从对照组的62.45μm^3/h减小为1.66μm^3/h;糖溶液的标准化断点黏度与标准化断点模量均和重结晶速率具有良好的线性相关性,相关系数分别为r^2=0.92和r^2=0.95。以上结果表明在冷冻浓缩过程中,糖溶液的流变性与其冰晶生长有关,添加亲水胶体可降低糖溶液的重结晶速率,延缓冰晶生长,并可借此预测和判断冰的重结晶速率,为工业生产节约成本。该研究为亲水胶体,尤其是罗望子胶降低重结晶速率、控制冰晶大小以及提高冷冻甜品感官品质的应用奠定理论依据。

To investigate the effect of rheological properties of frozen dessert solutions such as ice cream on the growth of ice crystals in frozen products,sugar solutions containing 0.3%(w/w)of different hydrocolloids(xanthan gum,tamarind seed gum,guar gum,carboxymethylcellulose and locust bean gum,respectively)were prepared.The water content of sugar solutions were sequentially reduced by 0%,15%,30%,45%,60%and 75%to simulate the freezing process.The effects of viscoelasticity of solutions on the rate of recrystallization were studied using rheology and cryomicroscopy techniques.Results showed that the rheology of sugar solutions supplemented with different hydrocolloids had significant effects on the recrystallization rate by comparing with control group without hydrocolloid.And the tamarind seed gum reduced the recrystallization rate from 62.45μm 3/h of control group to 1.66μm 3/h which exhibiting the most significant effect among all the samples.Both standardized breakpoints of viscosity and modulus of sugar solution presented good linear correlations with the rate of recrystallization(correlation coefficients of r 2=0.92 and r 2=0.95,respectively).Above results indicated that the rheological properties of sugar solutions with hydrocolloids during freezing process were related to the growth of ice crystals.Supplementation of viscous hydrocolloids could reduce the rate of recrystallization,delay ice crystal growth,and predict and judge the ice recrystallization rate,and thus saving costs for industrial production.This study established a theoretical foundation for the application of hydrocolloid,especially tamarind seed gum,on reducing recrystallization rate,controlling ice crystal size and improving sensory quality of frozen desserts.