【作者】 Khamis Ali Omar；

【导师】 王兴国；

【作者基本信息】 江南大学 ， 食品科学， 2010， 硕士

【摘要】 亚麻子油(Flaxseed oil, FO)是一种不稳定的植物油,含有以α-亚麻酸(ALA)为主的大量的多不饱和脂肪酸。在确保高质量的油脂及油脂产品以及延长它们保质期的各种有效方法中,加入合适的抗氧化剂及采用微胶囊化被认为是经济有效的方法。亚麻籽油的稳定化可望延长其货架期,拓展其应用范围。近期研究发现,FO对人体有许多有益的功能。FO所含有的大量的ALA是人体必需脂肪酸之一,能够通过机体转化为EPA和DHA。因此,FO对人体的生长发育及智力发展有益,同时也能够预防及治疗心脏病、关节炎、炎症及自身免疫性疾病。在FO中存在的生育酚主要是γ-生育酚,这种类型的生育酚在抑制血小板聚集及血栓形成、降低低密度脂蛋白、延缓动脉内的血栓形成方面更为有效。在超声辅助提取的条件下,采用L9(3)4正交设计对FO得率、β和γ生育酚的得率以及总氧化值进行了优化,并将优化得到的结果同索氏提取得到的结果进行了比较。结果显示,在30℃,底物溶剂比为1：10的条件下,采用超声辅助提取30min, FO的得率为80.05%,而在60℃,底物溶剂比为1：20的条件下,索氏提取8h,FO的得率为100%。在20℃,底物溶剂比为1：10的条件下,采用超声辅助提取30min, p和γ生育酚的得率为40.39 mg/100 g油,而通过索氏提取的得率为56.37 mg/100 g油。同索氏提取相比,超声辅助提取得到的油的总氧化值要低一些。两种提取方法得到的油在脂肪酸组成方面没有显著差异(p<0.025)。以上结果说明,同索氏提取相比,超声辅助提取能够提高效率,节约能源,而且对环境无害。采用单一和混合抗氧化剂的方法来稳定FO,试验研究了Tp、TBHQ、MGC以及它们的混合物的还原能力,发现Tp和TBHQ的混合物几乎在任何浓度下都比其他抗氧化剂的混合物还原能力强(p<0.025)。同时,对DPPH清除自由基能力的研究显示,Tp和TBHQ的混合物或者Tp、TBHQ、MGC三种抗氧化剂的混合物较理想,较其他混合物强。研究了在高温下,添加及不添加抗氧化剂的FO的氧化稳定性。采用的抗氧化剂为Tp、TBHQ和MGC以及它们按不同比例混合的混合物。在60℃的条件下保存20天,以FO的过氧化值(PV)和茴香胺值作为氧化程度的指标。结果显示,TBHQ200+Tp400+MGC200、Tp400+TBHQ200、TBHQ200+MGC200和Tp200+TBHQ100对控制FO的氧化有良好效果(下标表示mg/kg)。Rancimat试验表明,TBHQ200+Tp400+MGC200是最有效的抗氧化剂配方,接下来是TBHQ200+MGC200、Tp400+TBHQ200TBHQ100+Tp200+MGC100、TBHQ100+MGC100和Tp200+TBHQ100。由于人们更倾向于天然的物质及最少的食品添加剂的添加量,因此在使用多组分抗氧化剂时,可以向其中加入一些天然的物质以达到协同抗氧化的效果,同时也能降低脂质中人工合成抗氧化剂的量,而Tp+TBHQ是较好的选择之一。通过响应面分析法(RSM)得到采用FO、大豆磷脂和黄原胶制备小颗粒的亚麻籽油滴(FOD)和高微胶囊化效率(M.E.E)的最佳条件。阿拉伯胶和麦芽糊精的比例保持1：1不变,主要研究了FO的加入量(20-35%),卵磷脂(1-2%)和黄原胶的加入量(0.1-0.4%)对乳化效果及喷雾干燥颗粒的影响。结果显示,响应面模型能够显著地描述各因素对乳化效果及喷雾干燥颗粒的影响,其决定系数分别为0.9963和0.9944。通过优化,得到的最优条件为10%的阿拉伯胶和麦芽糊精,22.78%(w/w)的油酸,1.14%(w/w)的大豆磷脂和0.10%(w/w)的黄原胶,在此条件下,FOD为446.9 nm,M.E.E为92.3%,在储存10周内具有较好的氧化稳定性。更多还原

【Abstract】 Flaxseed oil (FO) is one among unstable vegetable oils due to its high content of polyunsaturated fatty acids (PUFA) which is mainly composed of alpha linolenic acid (ALA). Among the effective ways to ensure a high quality of lipids and lipid-containing products and prolong their storage time, the addition of suitable antioxidants and use of microencapsulation are considered to have good techno-economic values. The stabilization of flaxseed oil is expected to help increase its shelf life and use to different applications.FO is found recently to have many beneficial functions to human health. ALA, which occurs in large amounts in FO, is one among the essential fatty acids and may also be converted in the body to eicosapentaenoic acid (EPA) and decosahexaenoic acid (DHA); hence, it may help for essential growth and development and also is believed to be associated with the prevention and treatment of heart disease, arthritis, inflammatory and autoimmune diseases. The major tocopherols found in FO are y-tocopherols which are considered more potent in inhibiting platelet aggregation and thrombogenesis, low density lipoprotein and delaying intra-arterial thrombus formation.Orthogonal array design (L9 (3)4) was applied to optimize FO yield,β-andγ-tocopherols yields (mainly tocopherols found in FO) and total oxidation value (totox value) using ultrasound assistance extraction (UAE). The optimized results were then compared with the one extracted by Soxhlet extraction (S.E). The results revealed that 80.05% FO yield can be extracted for 30 min,30℃and 10:1 solvent/solid ratio by UAE compared to 100% yield obtained by 8 h,60℃and 20:1 solvent/liquid ratio by S.E.β-andγ-tocopherols yielded 40.39 mg/100 g oil at 30 min,20℃and 10:1 solvent/liquid ratio by UAE compared to 56.37 mg/100 g oil by S.E. Totox value of FO by UAE was lower compared to S.E. No significant different were shown for fatty acids between both extraction methods (p<0.025). UAE is capable to save time, energy and is environmental friendly.Stabilizing of FO with individual and different mixtures of antioxidants was studied. In vitro tests of tea polyphenols (Tp), tert-butylhydroquinone (TBHQ) and monoglyceride citrate (MGC) with their different mixtures as to their reducing power revealed that the reductive capability of Tp+TBHQ was found to be stronger compared to other mixture of antioxidants at almost all concentration levels studied (p< 0.025). However, DPPH radical scavenging activity had shown both the ternary mixture and the binary mixture of Tp+TBHQ of the antioxidants were more effective compared to other mixtures. Oxidation stability of FO in the absence and presence of antioxidants as a function of time at high temperature was also investigated. Tp, TBHQ and MGC with their mixtures at different concentration levels were used whereby peroxide value (PV) and p-anisidine value of FO were determined as indicators of oxidation at 60℃during 20 days. The results revealed that TBHQ200+Tp400+MGC200, Tp400+TBHQ200, TBHQ200+MGC200 and Tp2oo+TBHQ100 as the best for controlling oxidation in FO (subscript denotes in mg/kg). On Rancimat tests conducted, showed the most effective antioxidant formulation was ternary mixture of TBHQ200+Tp400+MGC200 followed by TBHQ200+MGC200, Tp400+TBHQ200 TBHQ100+Tp200+MGC100, TBHQ100+MGC100 and Tp200+TBHQ100.Due to worldwide preference of naturalism and minimization in using food additives, the use of multi-component antioxidants, wherein some natural substances is included to achieve synergistic antioxidative activity, Tp+TBHQ would be a better choice for minimizing the additions of synthetic antioxidants in food lipids.Response surface methodology (RSM) was used to establish optimum conditions for FO, soy lecithin and xanthan gum to yield stable flaxseed oil droplet (FOD) size and high microencapsulation efficiency (M.E.E). Gum arabic and maltodextrin were used at constant ratio of 1:1. FO loading (20-35%), lecithin (1-2%) and xanthan gum (0.1-0.4%) were studied regarding their effects on emulsion and the spray dried powder. Results indicated that response surface models significantly fitted to all response variables studied. Regression models describing variations of responses of FOD size and M.E.E showed high coefficient of determination (R2) of 0.9963 and 0.9944 respectively. Overall numerical optimization predicted a desirable system attainable using gum arabic and maltodextrin each at an amount of 10%(w/w),22.78%(w/w) FO loading,1.14%(w/w) soy lecithin and 0.10%(w/w) xanthan gum, which resulted into FOD size of 446.9nm, M.E.E of 92.3% and good stability towards oxidation during 10 weeks of storage tests.更多还原