哈医大精品课程营养与食品卫生学第一章营养学基础2.ppt

碳水化合物 Carbohydrates Main contents Definition of carbohydrates Classification of carbohydrates Digestion absorption of CHO Functions of carbohydrates Disorders related to CHO metabolism Dietary reference intakes of CHOs Carbohydrates are one of the three macronutrient types that provide energy to our bodies. Carbohydrates contain carbon, hydrogen, and oxygen. 碳水化合物：属三大能量营养素之一，主要由碳、氢、氧构成。 We obtained carbohydrates predominantly from plant foods such as fruits, vegetables, and grain. Monosaccharides-Glucose（葡萄糖） Glucose is the most abundant sugar molecule found in our diets and in our foods. Monosaccharides-Fructose（果糖） Fructose is also called fruit sugar. Fructose is the sweetest natural sugar, occurs naturally in fruits and vegetables. Monosaccharides-Galactose（半乳糖） Galactose does not occur alone in foods. It joins with glucose to create lactose, one of the disaccharides. Disaccharide（双糖） Disaccharide: A carbohydrate compound consisting of two sugar molecules joined together. Disaccharides– Lactose（乳糖） Disaccharides—Maltose （麦芽糖） Maltose: also called malt sugar, consist of two molecules of glucose. It does not generally occur by itself in foods, but results as a by-product of digestion. Disaccharides—Sucrose（蔗糖） Sucrose is composed of one glucose molecule and one fructose（果糖） molecule. 哪种双糖最甜--麦芽糖，蔗糖，乳糖？ Oligosaccharide（寡糖） Oligosaccharide are composed of 3 to 10 monosaccharides. The most common oligosaccharides are raffinose （棉籽糖）and stachyose（水苏糖）. They can not be degraded by enzymes in the small intestine, but can be broke down in the large intestine. Polysaccharides（多糖） Polysaccharides Polysaccharide--Starch Starch: A polysaccharide stored in plants and is the storage form of glucose in plants.（淀粉是葡萄糖在植物中的贮存形式） Our bodies easily digest most starches， we call them digestible starch(可吸收淀粉）. 根据其结构可分为直链淀粉（amylose）和支链淀粉（amylopectin），前者易使食物老化，后者易使食物糊化（gelatinization ）。 However, some starch in plants is not digestible and is called resistant starc