【作者】 徐子剑；

【导师】 王兴国；

【作者基本信息】 江南大学 ， 粮食、油脂及植物蛋白工程， 2012， 硕士

【摘要】 涂抹脂近年来在我国发展迅速,但是由于原料中添加了氢化油,涂抹脂产品中一般含有10%左右的反式脂肪酸,产品的营养品质问题突出,以不含反式脂肪酸的油脂取代氢化油开发出零反式脂肪酸涂抹脂产品具有明显的实际价值。以富含油酸、亚油酸等的葵花籽油与价格较为低廉的棕榈油硬脂为原料,通过酶法酯交换技术的改性,解决其简单混合而存在的相容性差的问题,可开发出新型零反式酸健康涂抹脂。全面分析了6种商品化涂抹脂产品的物理化学性质,结果发现:6种商品化涂抹脂的配方差别比较大,其脂肪酸组成、固体脂肪含量、晶体形态等性质上较为相似。在综合考虑性能和组成特征基础上,确定酶法酯交换的底物为棕榈油硬脂和葵花籽油。以脂肪酶(Lipozyme RM IM)作为催化剂,进行酶法酯交换反应。单因素试验结果可知:选取机械搅拌速度为200 r/min、脂肪酶添加量为8%、反应温度为70 oC、反应时间为3 h时最佳。在单因素试验的基础上,通过响应面法优化反应条件,研究了脂肪酶添加量、反应温度、反应时间对酯交换反应的影响及交互作用,得到最优反应条件:脂肪酶添加量为8.51%,反应温度74.3 oC,反应时间3.36 h时,反应的酯交换度为68.61%。采用短程分子蒸馏去除酯交换产生的游离脂肪酸,使酯交换油脂的酸价降至0.12 mgKOH/g。在此基础上,对酯交换反应前后油脂的甘油三酯组成比较后发现,主要甘油三酯种类并未发生改变,但是相对含量发生了较大改变,酯交换反应后的甘油三酯组成更加平衡,适合于涂抹脂产品。结晶行为分析后发现,酯交换反应后油脂由β晶型转变为β′晶型,结晶速率减慢,并改善了晶体形态和棕榈油的后结晶现象。将酯交换油脂作为基料油,添加40%的水相和0.7%的乳化剂,以产品的晶体形态和物性分析结果为评价指标,选取的最优乳化剂配方为:大豆磷脂:单双甘油酯:STS=2:1:1(或1:2:1),制备的涂抹脂品质最好,与商品化涂抹脂比较没有显著差异,并且能很好地抑制产品中油脂晶体的生长,维持晶型的稳定。选取两种商品化涂抹脂加热熔化,按照实验室方法重新制备后,在晶体形态、延展性、黏着性等性质上与原来的商品化涂抹脂比较差距不显著,产品性质总体上较好。更多还原

【Abstract】 Spread has been developed rapidly in China in recent years. However, due to the raw materials added hydrogenated oil, the system is generally contain about 10% trans fatty acids, and the product has the outstanding nutritional quality problem. Replacing hydrogenated oils with trans-free oil has obviously practical value. The problem of poor compatibility of the simple mixture can be resolved through enzymatic interesterification, using sunflower oil rich in essential oleic acid, linoleic acid and cheap palm stearin as materials. Meanwhile, new trans-free healthy spread can also be developed. A comprehensive analysis of the physical and chemical properties of six kinds of commercialized spreads was conducted. The results showed that the formulations differed greatly, but fatty acid composition, solid fat content and crystal morphology were very similar. Based on the comprehensive consideration of properties and composition, sunflower oil and palm stearin were selected as substrates for enzymatic interesterification.Enzymatic interesterification was catalyzed by Lipozyme RM IM. The single factor test results showed that the optimal conditions were as follows: stirring speed of 200 r/min, lipase amount of 8 %, reaction temperature of 70 oC and reaction time of 3 h. Furtherly, the reaction conditions were optimized through response surface methodology. And the effects of lipase amount, reaction temperature, reaction time on the interesterification reaction and their interactions were investigated. The optimal reaction conditions obtained were a lipase amount of 8.51 %, a reaction temperature of 74.3°C and a reaction time 3.36 h. Under the optium conditions the interesterification degree was 68.61%. The free fatty acids generated in the interesterification process were removed by short-range molecular distillation. After that, the acid value of the interesterification product dropped to 0.12 mgKOH/g.Through analysing and comparing the main triglyceride species of the oil before and after the interesterification, we found that the main triglyceride species did not change, but their relative content undergone great change. After interesterification, triglyceride composition was more balanced and more suitable for spread products. The crystal form of fats changed fromβtoβ’ after interesterification. The crystallization rate slowed down, and the crystal morphology and recrystallization phenomenon of palm oil were improved.Water of 40 % and emulsifier of 0.7 % were added into the base oil of interesterification product. And the crystal form and physical analysis results were taken as the evaluation indicators for the evaluation and selection of the optimal emulsifier formulations. The optimal soybean emulsifier’s formulation was: ecithin: monoglyceride and diglyceride: STS =2:1:1 or 1:2:1. The quality of thespreads produced using this formulation were the best. and did not differ significantly with the commercial ones. Moreover, they can inhibit the growth of fat crystals in the product as well as maintaining the stability of the crystal. Two commercial spreads were chosen to be melted, and then re-prepared according to the laboratory method. The product had little differences with original commercial spreads in the properities of crystal microstructure, spreadability and adhesiveness, so the properities in general were better.更多还原