Tags : FSSAI

Scope

This method is a routine reference for determining the moisture content of cereals and cereal products. It applies to the following products: wheat, durum wheat, rice (paddy, husked, and milled rice), barley, millet, rye, oats and rolled oats, triticale, sorghum and kaffir in the form of grains, milled grains, semolina or flour, pulses (whole and dehulled), macaroni products, solvent extracted and expeller pressed flours, cereal and legume (pulses) flours, bran, cornflakes, corn flour, couscous, tapioca sago and palm sago starch flour, textured soy protein products, etc. This method is not applicable to malted foods.

Caution

• Hot air oven: Always wear insulated gloves when handling samples in the heated oven. Open hot ovens with care. Stand to one side when opening the door to avoid high temperatures.
• Desiccators: Exercise extreme caution when opening and closing desiccators.

Principle

The sample is ground, if pre-conditioning is required. A test portion is dried at a temperature of 130 ± 3 °C to a constant mass. The loss in mass is expressed as a percentage.

Equipment/Apparatus

1. Analytical balance: Accurate to 0.001 g.
2. Grinding mill: Must have the following characteristics:
   • Made of material that does not absorb moisture.
   • Easy to clean with minimal dead space.
   • Enables rapid and uniform grinding without appreciable heat development and minimal contact with outside air.
   • Adjustable to obtain particles that pass through a 1.0 mm IS sieve. Cold grinding mills can be used.
3. Moisture dishes: Made of porcelain, silica, glass, or aluminum, approximately 7.5 cm wide and 2.5 cm deep with tight-fitting lids.
4. Convection oven: Thermostatically controlled to maintain a temperature between 130 ± 3 °C.
5. Desiccators: Containing desiccant (Silica gel/P₂O₅, CaCl₂).

Sample Preparation

Refer to the manual for sample preparation

Method of Analysis

1. Weigh approximately 5.0 g of the laboratory sample to the nearest 0.001 g in a pre-dried and weighed moisture dish with its lid.
2. Place the dish with its lid underneath in the oven for 2 hours.
3. Start timing once the oven reaches 130 °C after the dishes are placed inside.
4. After 2 hours, cover the dish while still in the oven, and then transfer it to the desiccator.
5. Cool the dish in the desiccator.
6. Once cooled to room temperature (25 ± 3 °C) after 30-45 minutes in the desiccator, weigh it to the nearest 0.001 g.
7. Repeat the drying process until a constant weight is achieved.

Calculation with Units of Expression

The moisture content, expressed as a percentage by mass of the product, is calculated as follows:

\text{Moisture (%) =} \left( \frac{W1 - W2}{W1 - W} \right) \times 100

Where:

• $W_w$ = Mass in g of the empty dish
• $W_1$ = Mass in g of the dish with the test portion before drying
• $W_2$ = Mass in g of the dish with the material after drying

References

1. IS 4333 (Part II): 2002 Methods of Analysis of Food Grains Part II Moisture
2. AOAC Official Method 926.06 Macaroni Products Preparation of Samples
3. AOAC Official Method 925.10 Solids (Total) and Loss on Drying (Moisture) in Flour Air Oven Method