氢化植物油

作者:养身殿  于 2009-1-19 16:02 发表于 最热闹的华人社交网络--贝壳村

通用分类:其它日志|已有2评论

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什么是氢化植物油

  氢化植物油也叫反式脂肪酸,俗称奶精、乳马林或是人造奶油,是普通植物油在一定温度和压力下加氢催化的产物。因为它不但能延长保质期,还能让糕点更酥脆;同时,由于熔点高,室温下能保持固体形状,因此广泛用于食品加工。 氢化过程使植物油更加饱和。或使其中的顺式脂肪酸变为反式脂肪酸。这种油存在于大部的西点与饼干里头。还有我们去吃韩国烤肉时,旁边放的那一块奶油或是奶油饼里所包的都是这种油脂。珍珠奶茶中是奶香就是使用氢化植物油与甜味剂、香料、木薯粉等材料调制,对身体有害,不宜多吃。

危害

   氢化植物油的结构在化学上是呈反式的键结,它比真正的奶油要毒上好几百倍。最近研究表明,反式脂肪酸对人体的危害比饱和脂肪酸更大。膳食中的反式脂肪酸 每增加2%,人们患心脑血管疾病的风险就会上升25%。还有实验发现,反式脂肪酸可能会引发老年痴呆症。 Time杂志在曾经公布,氢化植物油在自然界是不存在的,也就是说在自然情况下,人体是无法吸收消化这种油脂的。食用后会对肝脏产生伤害,进而破坏人体细 胞膜,造成细胞的缺陷,影响细胞未来的复制与再生,长期大量使用,可以使人产生身体过早衰老的症状。
  我国对氢化植物油的使用尚无明确标准。如果在配料表上注有“氢化植物油”“植物奶油”“起酥油”等字样,就意味着食品中含有反式脂肪酸。另外,咖啡伴侣的主要配料“植脂末”也是“氢化植物油”,珍珠奶茶中乳香的主要来源也是“氢化植物油”。
  氢化植物油不含有胆固醇类物质且相对于动物奶油价格低廉,因此,很多人养成以人造奶油替代动物 奶油的习惯。但最近的研究表明,大量食用氢化植物油会对心脏产生一定的危害。还有实验发现,人造奶油中的反式脂肪酸易引发老年痴呆症。但学术界对这些说法 意见不统一,关于反式脂肪酸对人体的危害也是近年来争论的热点。

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1 回复 养身殿 2009-1-19 16:11
What is Hydrogenated Oil?

Oils have been hydrogenated since the 1930s to prolong their shelf life and make the oils more stable. Hydrogenated oil is oil in which the essential fatty acids have been converted to a different form chemically, which has several effects on the oil. Hydrogenated oil is far more shelf stable, and will not go rancid as quickly as untreated oil. It also has a higher melting point, and is often used in frying and pastries for this reason. Finally, the chemical structure of the oil is changed, which scientists in the 1990s began to realize could result in health effects.

Hydrogenated oil is made by forcing hydrogen gas into oil at high pressure. Both animal and vegetable fats can be and are hydrogenated. In general, the more solid the oil is, the more hydrogenated it is. Two common examples of hydrogenated oil are Crisco and margarine. In the 1990s, it was realized that these products might have deleterious health effects, a tragic irony since they were originally produced and promoted as being healthier than conventional oils.

The unstable fatty acids in oils happen to be unsaturated fats, which have been determined to be healthier for consumers, acting to reduce cholesterol in some cases. When hydrogenated oil is made, these healthy fats are converted into a new type of fatty acid, known as a trans fat. Trans fats are not at all good for one's health. In some highly hydrogenated oils like margarine, trans fats can make up almost half of the total fat content.

Trans fatty acids work to increase LDL, or "bad" cholesterol, and they also decrease HDL cholesterol, which is "good" cholesterol. This means that the fats in hydrogenated oil are far more damaging than even saturated fats, which medical professionals have already determined to be harmful. There is also evidence to suggest that trans fatty acids may bioaccumulate in the body, because the digestive system has difficulty figuring out what to do with them. As a result, a diet high in trans fats will result in weight gain.

Consumption of hydrogenated oil has been linked with diabetes, coronary disease, and obesity in a wide number of scientific studies. In the 1990s, many activists began to lobby for clear food labeling, indicating when products contained trans fats. Other activists went further, attempting to ban trans fats because of their detriment to human health. All medical professionals agree that people should limit their consumption of hydrogenated oil to avoid exposure to trans fats, and should eat foods with healthy fats such as nuts, avocados, and olive oil.
1 回复 养身殿 2009-1-19 16:13
氢化植物油,含“反式脂肪酸”。反式脂肪是一种广泛用于膳食烹调和食品加工的油脂,它以不饱和脂肪酸为主的植物油为原料,经加热并适度引入氢分子,使原有的脂肪酸发生结构改变,将顺式双链变成反式双链,把液态不饱和脂肪变成易凝固的饱和脂肪酸。反式脂肪酸具有耐高热,可塑性强,不易变质腐败,便于存放保管等特点。同时,还可增加食品可口程度,让食品外形更加美观,且成本低廉等优点,因而被广泛应用于食物烹调和食品加工。

反式脂肪酸是不健康的成分,它对心脏的损害程度远远高于任何一种动物油。含有氢化植物油的食品都可能含有反式脂肪酸,比如饼干、面包、西式糕点、巧克力派、沙拉酱、炸薯条、炸鸡块、洋葱圈、咖啡伴侣、热巧克力等。但是,反式脂肪酸的名字有很多,一般配料表里标明“氢化植物油”、“植物起酥油”、“ 人造黄油”、“人造奶油”、“植物奶油”、“麦淇淋”、“起酥油”或“植脂末”等,都含有反式脂肪酸。

反式脂肪酸对人体的危害比饱和脂肪酸更大,它不仅影响人体免疫系统,还会提高对人体有害的低密度脂蛋白胆固醇含量,降低对人体有益的高密度脂蛋白胆固醇含量,促进动脉硬化,增加血液黏稠度和凝聚力。实验证明,摄入占热量6%的反式脂肪酸人群比摄入占热量2%的反式脂肪酸人群的全血凝集程度明显增加,可见反式脂肪酸容易使人产生血栓,导致心肌梗塞和脑栓塞。反式脂肪酸能通过胎盘直接转运给胎儿,母亲摄入人造黄油可通过母乳喂养而使婴儿被动摄入反式脂肪酸,从而减少男性荷尔蒙分泌,影响胎儿和婴幼儿的生长发育,并对中枢神经系统的发育产生不良影响,使思维不敏捷,记忆减退。反式脂肪食品产热多,常吃易导致人肥胖。最近,美国哈佛大学的一个研究小组发现,反式脂肪酸是糖尿病发病的危险因素,它比饱和脂肪酸的危害更大。通过测算,如果将占食物总热量2% 的反式脂肪酸换为不饱和脂肪酸,就可使糖尿病的发生危险减少40%。

鉴于反式脂肪酸对人体健康的危害,欧洲丹麦是世界上第一个限制食品中反式脂肪酸含量的国家,法律规定从2004年1月1日起油脂中反式脂肪含量不得超过2%;美国在2004年8月发表的饮食指南中,发出了日均反式脂肪摄入量应在摄取总热量的1%以下的劝告。美国纽约市所有餐饮业已从2007年7月 1日开始,停用反式脂肪的烹调油,并从2008年7月1日起所有餐饮业完全封杀含有反式脂肪的食品。

我国对反式脂肪在食品中应用尚无明确限制,为了减少肥胖、糖尿病和心血管疾病的发生,中老年人还是远离反式脂肪食品为好。在购买食品时请注意配料,凡标明含精炼植物油、氢化植物油、氢化油、人造奶油、人造黄油者,请避而远之。

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