Effects Of Cooking On Functional Component And Nutrition Assessment

Vegetables are a kind of important food in human diet. Vegetables contain less protein, do not contain or contain only trace amounts of fat. Because the people’s eating habits and food structure in our country is mainly based on the vegetarian diet, so the vegetable is the important source of the human body carbohydrate, vitamin, protein and other nutrients. In addition, vegetables are one of the important sources of human dietary fiber. Fresh vegetables are high potassium and low sodium foods, and intaking of fresh vegetables for hypertension patients have a positive role in the control of blood pressure. Therefore, eating more vegetables can improve blood glucose control in patients with diabetes, improve the condition of hypertension, reduce blood lipids and reduce the risk of complications. There is a variety of cooking methods, different cooking methods will lead to a different degree of loss of nutrients in vegetables. Therefore, this paper studied the effects of different cooking methods on nutrients in vegetables, and established a new mathematical model to evaluate the changes of nutritional value of vegetables before and after cooking.In the this paper, the impact of boiling1-4 mins, steaming 1-4 mins, frying in150℃、175℃、200℃、225℃ 2mins, and in180℃frying in 1mins、1.5mins、2mins、2.5mins on a group of vegetables’ VC、VB2、β-carotene、flavones、polyphone、lycopene and chlorophyll was detailed studied.Studying the effects of cooking methods on vitamin showed that vitamins are a kind of complicated-structure, unstable chemicals. So cooking will make vitamins loss, and different methods of cooking have different degree of loss. For vitamin C, vitamin B2 of the water soluble vitamins, boiling and steaming will make its due to dissolution and loss more, stir frying because of high temperature will destroy vitamins in vegetables and the loss. For the β-carotene which is fat soluble vitamin, frying will make the loss more.Studying the effects of cooking methods on flavones、polyphone showed that in a certain range, the content of total flavonoids, total phenols and other functional components increased with the frying process. However, when the frying temperature is too high or frying time is too long, it will be the total flavonoids, total phenolic content decreased. Boiling will make the above ingredients gradually reduced along with the cooking time.Studying the effects of cooking methods on vegetables’ calcium, iron, and zinc showed that because of minerals is a kind of stable material, it didn’t change with high cooking temperature. But minerals exist in the cell sap, cooking heating or stir fry will damage vegetables of the cellular structure to reduce vegetables’ cell sap and cause minerals losses.Using principal component analysis to establish a mathematical model to evaluate the nutritional value of vegetables before and after cooking. The results showed that: the fresh vegetables owe highest nutritional value. No matter what kind of cooking methods will make the overall nutritional value of vegetables is lower. Boiling can make the vegetables lose more nutrients, and the nutritional value of the vegetables after boiling is lower compared with other methods. Steaming time is short, the nutritional value of vegetables is higher, but when the steam system for a long time, the vegetables will loss of more nutrients. Stir frying has the characteristics of short time and high temperature. Compared with other cooking methods, it can keep the nutritional value of vegetables. However, the stir frying time should not be too long; otherwise the unstable nutrients are easily to be oxidized. Stir frying temperature is not easy too high, on the one hand will make the ingredients easily become paste, affecting the taste, on the other hand, it will also damage the nutrients in vegetables. As can be seen from the data, stir frying temperature at 150-180℃is better and the time should be controlled at about 1min-2min.