【作者】 冀聪伟；

【导师】 金青哲；

【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】 我国猪油资源丰富,长期以来,猪油以其特有的香味和易消化吸收的特点广受消费者的欢迎。然而,近年来随着人们生活水平的逐步提高,猪油因存在胆固醇含量高、油脂晶体粗大等问题越来越不被人们接受。本文针对猪油存在的上述问题,进行了猪油精炼工艺和深加工技术的研究,以期开发一种低胆固醇猪油基焙烤起酥油产品,解决市场上出现的猪油资源过剩问题。首先,对猪油精炼工艺进行了改进。比较了95%乙醇、活性白土、活性炭、硅胶、β-环糊精(β-CD)对猪油中胆固醇的脱除效果。结果表明:β-CD脱除猪油中胆固醇的效果最佳。为了将β-CD脱除胆固醇工艺应用到猪油精炼工艺之中,研究了精炼过程中β-CD脱除胆固醇工艺对其脱除效果的影响以及脱除工艺对猪油稳定性的影响。结果发现,精炼过程中游离脂肪酸的含量对脱除胆固醇的效果影响显著,随着游离脂肪酸含量的增加脱除效果明显下降;β-CD脱除胆固醇工艺可降低猪油中游离脂肪酸和过氧化物的含量,在一定程度上增强猪油的稳定性。结合工业实践,得出猪油脱胶脱酸后再进行β-CD脱除胆固醇的处理最为合理。另外,由于国内外猪油以及β-CD品质存在差异,本文采用均匀设计方法对β-CD脱除胆固醇工艺进行了优化,得到最佳工艺条件为β-CD添加量5.79%、温度59 oC、时间89 min,在此条件下胆固醇脱除率可达96%。随后,对β-CD-胆固醇包合物中胆固醇的释放条件也进行了优化,在pH9.5、乙醇浓度95%、搅拌转速为200 r/min、回流时间为40 min的条件下胆固醇释放率可达到95.3%,将经释放处理后的β-CD进行重复利用,发现其依然具有良好的包合吸附特性。其次,本论文进行了以猪油和棕榈硬脂为原料经酶法酯交换制备零反式脂肪酸起酥油基料油的研究。以混合体系在20 oC、25 oC下的固体脂肪含量(SFC)及熔点为指标,考察了反应温度、酶用量以及反应时间对酯交换反应的影响,得出在反应温度60 oC,酶用量8%(以底物质量计,w/w),反应时间1 h的条件下酯交换反应可达到平衡。通过对混合体系酯交换前后的相容性、SFC曲线、晶型、熔化性质等分析发现经酯交换后混合体系相容性得到显著改善;SFC曲线变得更加平滑;晶型由以β型结晶为主转变为以β′型为主,结晶更加均匀细腻。通过对混合体系酯交换前后甘油三酯组成和脂肪酸组成的分析得出:混合体系甘油三酯组成发生显著变化,不对称甘油三酯含量显著增加;脂肪酸组成基本无变化,无反式脂肪酸生成。最后,对混合体系酯交换前后制备的起酥油品质进行了应用评价。结果表明混合体系经酯交换后制备的起酥油具有更好的酪化性,焙烤的面包品质更佳。更多还原

【Abstract】 Due to its unique flavor and easy digestive properties, lard has a long edible history in China and is very popular with Chinese people. However, with the improving of people’s living standard , lard gradually became less and less accepted because of its high cholesterol content and bulky crystal.The purpose of this paper is to develop a low cholesterol lard-based baking shortening and solve the problem of lard resources surplus by studying the refining and deep processing techniques of lard.Firstly,this paper improved the lard refining process and compared the effect of 95% ethanol, activated Earth, activated carbon, silica gel andβ-cyclodextrin (β-CD) on removing cholesterol from lard. The results showed that the cholesterol removal rate ofβ-CD was the best. Furtherly, the effect ofβ-CD on removal of cholesterol during the lard refining and stability of lard were studied . The study results showed that during the refining process free fatty acids content had important effect on the removal of cholesterol.The cholesterol removal rate decrease as the free fatty acid content increase; The cholesterol removal process ofβ-CD reduced the content of free fatty acid and peroxide in lard, and strengthened the stability of lard. Combined with industry practice, it is better to add the cholesterol removal process ofβ-CD after degumming and deacidification of lard. Since the quality of lard andβ-CD are varied at home and abroad, this paper optimized the cholesterol removal process ofβ-CD by uniform design method and obtained the best conditions: reaction temperature 59 oC,β-CD 5.79% , reaction time 89 min. Under this condition, the cholesterol removal rates was up to 96% . Theβ-CD release rate ofβ-CD- cholesterol complex compound was also optimized, and got the optium conditions: pH9.5, ethanol concentration of 95%, mixing speed of 200 r/min and reflow time of 40 min. Under the optium conditions theβ-CD release rate was up to 95.3%. The results revealed that the embedding capability of the recyclingβ-CD was as effective as before.Secondly, baking shortening produced by enzymatic interesterification using lard and palm stearin as raw materials was studied and the influence of temperature, enzyme addition and reaction time were also discussed. The reaction equilibrium conditions were as follows: temperature of 60 oC, enzyme addition of 8% and reaction time of 1 h. After interesterification, the compatibility of mixed fats got better; SFC curve became smoother; crystalline transformed fromβtoβ′primarily and crystallization got more uniform. Besides, the triglyceride and fatty acid composition before and after interesterification were compared, and found that the asymmetric TAGs increased significantly, there was no change in fatty acid and no trans fatty acid was formed.Finally, the quality of shortening before and after interesterification was evaluated . The results showed that shortening after interesterification had better air-absorbing capacity, and could produce better quality baking bread.更多还原