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氫化植物油

作者:養身殿  於 2009-1-19 16:02 發表於 最熱鬧的華人社交網路--貝殼村

通用分類:其它日誌|已有2評論

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什麼是氫化植物油

  氫化植物油也叫反式脂肪酸,俗稱奶精、乳馬林或是人造奶油,是普通植物油在一定溫度和壓力下加氫催化的產物。因為它不但能延長保質期,還能讓糕點更酥脆;同時,由於熔點高,室溫下能保持固體形狀,因此廣泛用於食品加工。 氫化過程使植物油更加飽和。或使其中的順式脂肪酸變為反式脂肪酸。這種油存在於大部的西點與餅乾裡頭。還有我們去吃韓國烤肉時,旁邊放的那一塊奶油或是奶油餅里所包的都是這種油脂。珍珠奶茶中是奶香就是使用氫化植物油與甜味劑、香料、木薯粉等材料調製,對身體有害,不宜多吃。

危害

   氫化植物油的結構在化學上是呈反式的鍵結,它比真正的奶油要毒上好幾百倍。最近研究表明,反式脂肪酸對人體的危害比飽和脂肪酸更大。膳食中的反式脂肪酸 每增加2%,人們患心腦血管疾病的風險就會上升25%。還有實驗發現,反式脂肪酸可能會引發老年痴呆症。 Time雜誌在曾經公布,氫化植物油在自然界是不存在的,也就是說在自然情況下,人體是無法吸收消化這種油脂的。食用後會對肝臟產生傷害,進而破壞人體細 胞膜,造成細胞的缺陷,影響細胞未來的複製與再生,長期大量使用,可以使人產生身體過早衰老的癥狀。
  我國對氫化植物油的使用尚無明確標準。如果在配料表上注有「氫化植物油」「植物奶油」「起酥油」等字樣,就意味著食品中含有反式脂肪酸。另外,咖啡伴侶的主要配料「植脂末」也是「氫化植物油」,珍珠奶茶中乳香的主要來源也是「氫化植物油」。
  氫化植物油不含有膽固醇類物質且相對於動物奶油價格低廉,因此,很多人養成以人造奶油替代動物 奶油的習慣。但最近的研究表明,大量食用氫化植物油會對心臟產生一定的危害。還有實驗發現,人造奶油中的反式脂肪酸易引發老年痴呆症。但學術界對這些說法 意見不統一,關於反式脂肪酸對人體的危害也是近年來爭論的熱點。

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回復 養身殿 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.
回復 養身殿 2009-1-19 16:13
氫化植物油,含「反式脂肪酸」。反式脂肪是一種廣泛用於膳食烹調和食品加工的油脂,它以不飽和脂肪酸為主的植物油為原料,經加熱並適度引入氫分子,使原有的脂肪酸發生結構改變,將順式雙鏈變成反式雙鏈,把液態不飽和脂肪變成易凝固的飽和脂肪酸。反式脂肪酸具有耐高熱,可塑性強,不易變質腐敗,便於存放保管等特點。同時,還可增加食品可口程度,讓食品外形更加美觀,且成本低廉等優點,因而被廣泛應用於食物烹調和食品加工。

反式脂肪酸是不健康的成分,它對心臟的損害程度遠遠高於任何一種動物油。含有氫化植物油的食品都可能含有反式脂肪酸,比如餅乾、麵包、西式糕點、巧克力派、沙拉醬、炸薯條、炸雞塊、洋蔥圈、咖啡伴侶、熱巧克力等。但是,反式脂肪酸的名字有很多,一般配料表裡標明「氫化植物油」、「植物起酥油」、「 人造黃油」、「人造奶油」、「植物奶油」、「麥淇淋」、「起酥油」或「植脂末」等,都含有反式脂肪酸。

反式脂肪酸對人體的危害比飽和脂肪酸更大,它不僅影響人體免疫系統,還會提高對人體有害的低密度脂蛋白膽固醇含量,降低對人體有益的高密度脂蛋白膽固醇含量,促進動脈硬化,增加血液黏稠度和凝聚力。實驗證明,攝入占熱量6%的反式脂肪酸人群比攝入占熱量2%的反式脂肪酸人群的全血凝集程度明顯增加,可見反式脂肪酸容易使人產生血栓,導致心肌梗塞和腦栓塞。反式脂肪酸能通過胎盤直接轉運給胎兒,母親攝入人造黃油可通過母乳餵養而使嬰兒被動攝入反式脂肪酸,從而減少男性荷爾蒙分泌,影響胎兒和嬰幼兒的生長發育,並對中樞神經系統的發育產生不良影響,使思維不敏捷,記憶減退。反式脂肪食品產熱多,常吃易導致人肥胖。最近,美國哈佛大學的一個研究小組發現,反式脂肪酸是糖尿病發病的危險因素,它比飽和脂肪酸的危害更大。通過測算,如果將佔食物總熱量2% 的反式脂肪酸換為不飽和脂肪酸,就可使糖尿病的發生危險減少40%。

鑒於反式脂肪酸對人體健康的危害,歐洲丹麥是世界上第一個限制食品中反式脂肪酸含量的國家,法律規定從2004年1月1日起油脂中反式脂肪含量不得超過2%;美國在2004年8月發表的飲食指南中,發出了日均反式脂肪攝入量應在攝取總熱量的1%以下的勸告。美國紐約市所有餐飲業已從2007年7月 1日開始,停用反式脂肪的烹調油,並從2008年7月1日起所有餐飲業完全封殺含有反式脂肪的食品。

我國對反式脂肪在食品中應用尚無明確限制,為了減少肥胖、糖尿病和心血管疾病的發生,中老年人還是遠離反式脂肪食品為好。在購買食品時請注意配料,凡標明含精鍊植物油、氫化植物油、氫化油、人造奶油、人造黃油者,請避而遠之。

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