What are the national standard numbers for moisture in food in 2020?

There are many types of food, there are foods with high sugar content, foods with high oiliness, and foods with spicy taste, but the national standards for food moisture testing are still several, such as drying method, vacuum drying method, distillation method, Karl Fischer and so on, different standards are used for different food moisture testing, and there are also rapid detection methods CS-002 food moisture analyzer is widely used in the food industry flour, bacon, meat products, aquatic products, candy, fillings, condiments, peppers, dried fruits, biscuits, Baked goods, etc., it only takes a few minutes to test a sample, CCTV news, Chinese international channel has repeatedly reported that the use of production capacity has improved the efficiency of production, and has won praise from users.

The scope of food covers a lot, but the national standard for the detection of food moisture is universal direct drying method, vacuum drying method, Karl Fei group stove rest method, distillation method, etc., but there is not or wide industry standards, the national standard method for detecting food moisture only plays an arbitration role, and the real test is still the rapid method CS-002 food moisture meter to detect food moisture such as flour, cakes, fillings, dried fruits, etc.;

There is a wide variety of pastry foods. The degree of wetness and dryness of different types of pastries will vary greatly, so there should not be a uniform moisture content.

In the national standard GBT 20977-2007 "General Principles of Pastries", the water content limits of different types of pastries are specified in the form of a percentage of loss on drying, as shown in the figure below

In this standard, the direct drying method is applicable to the determination of moisture in grains and their products, aquatic products, soy products, dairy products, meat products and marinated vegetable products and other foods that do not contain or contain very little other volatile substances under 101 105, and is not suitable for samples with moisture content less than 100 g.

The vacuum drying method is suitable for the determination of moisture in foods that are easy to decompose such as sugar and monosodium glutamate, and is not suitable for the determination of samples with added other raw materials, such as toffee, gummies, etc., and is not suitable for samples with moisture content less than g 100 g.

The distillation method is suitable for the determination of moisture in foods containing more volatile substances, such as oils and spices, and is not suitable for samples with moisture content less than 1 g and 100 g.

The Karl Fischer method is suitable for the determination of moisture in food, the Karl Fischer volume method is suitable for samples with a moisture content greater than 100 g, and the Karl Fischer coulometric method is suitable for samples with a moisture content greater than 100 g.

The first method is the direct drying method.

2 Principle. Using the physical properties of water in food, the weight lost by drying in the sample is determined by volatilization method at kpa (one atmospheric pressure) and temperature 101 105, including hygroscopic water, partial crystal water and volatile substances under this condition, and then the moisture content is calculated by weighing the value before and after drying. 3

Reagents and materials.

Unless otherwise specified, the reagents used in this method are analytically pure. Hydrochloric acid: excellent pure.

Sodium hydroxide (NaOH): Superior pure.

Hydrochloric acid solution (6 mol l): measure 50 ml of hydrochloric acid and dilute to 100 ml with water.

Sodium hydroxide solution (6mol l): Weigh 24 g of sodium hydroxide, add water to dissolve and dilute to 100 ml.

Sea sand: take sea sand or river sand washed off the soil with water, first use hydrochloric acid (boil h, wash with water to neutral, and then use sodium hydroxide solution (boil h, wash with water to neutral, dry by 105 for later use. 4 Instruments and Equipment.

Flat aluminum or glass weighing flasks.

Electrically heated constant temperature drying oven.