Generally, it can be found from the food composition table, or it can be accurately measured by calorimeter. Put the sample to be measured into the combustion chamber of calorimeter for complete combustion, and use water to absorb all the released energy. When a millilitre of water rises once at normal pressure, it needs to absorb 4. 187 joules, and record the changes of water quality and water temperature, and make corresponding conversion.
The calorie of food samples is defined as: when heating 1 ml (with a mass of 1 g), the required calorie is 4.8 1 7 joules for every increase of1degree Celsius. [ 1]?
(1) staple food: such as rice, porridge, noodles, etc. If 80 calories are taken as the calculation unit, the calories of 1/4 bowls of rice, half bowls of porridge or half bowls of noodles commonly used in daily life are equivalent to 80 calories.
② Meat, tofu and eggs: 37 grams of lean meat, 20 grams of fat meat, 80 calories. 125 grams of milk, two teaspoons or half a tablespoon of oil are 80 calories. It is worth noting that the calorie of 1 boiled eggs is 80 calories, but the calorie of 1 fried eggs is 120 calories.
Vegetables: 600 grams of any vegetable equals 80 calories.
④ Seafood: 100g is about 80 calories.
⑤ Fruit: 300 grams of watermelon and 2 oranges, all of which are 80 calories.
Extended data
1. What is heat? The human body consumes energy all the time, and energy is provided by thermogenic nutrients in food. Nutrients that can produce calories in food are protein, fat, sugar and carbohydrate. They are oxidized to generate heat for the body to maintain life, grow and develop and exercise. When there is too much heat supply, the excess heat will be stored as fat. After a long time, the body will get fat.
2. Unit of calories: In nutrition, "kilocalories" is used as the unit of calories. 1 kcal is the heat required for 1L water to rise from 15℃ to 1℃.
There are three main ways to consume heat. The first part is basal metabolic rate, which accounts for about 65-70% of the total calorie consumption of human body. The second part is physical activity, which accounts for about 15-30% of the total calorie consumption. The third part is the thermal effect of food, which accounts for at least about 10%. The proportion of these three parts has been basically fixed.
Calorific unit: calories, 1 calories = 1000 calories.
Nutrients that can provide calories in the diet are sugar (carbohydrate), fat, protein, alcohol, organic acids and so on. The calories they contain are: sugar (carbohydrate) 4 calories, fat 9 calories, protein 4 calories, alcohol 7 calories and organic acid 2.4 calories.
To calculate the calories contained in food or diet, we must first know the weight of calorie nutrients, and then use the following formula to calculate:
Calories (kilocalories) = grams of sugar ×4+ grams of protein ×4+ grams of fat ×9+ grams of alcohol × 7.
The heat consumed by adults is utilized in three aspects: basic metabolism, activity and food thermal effect; During growth and pregnancy, the tissue structure needs extra heat.
References:
Baidu encyclopedia food heat meter