GB/T 5525-2025Vegetable fats and oils - Method for identification of transparency, odour and taste (English PDF)

5.1 Instruments and equipment

5.1.1 Glass colorimetric tube. 100 mL, inner diameter 25 mm.

5.1.2 Thermometer. 0 °C ~ 100 °C.

5.1.3 Incandescent lamp. Milky white glass bulb.

5.1.4 Constant temperature water bath. 0 °C ~ 100 °C, temperature control accuracy ±1 °C.

5.2 Operating method

5.2.1 When the fat and oil sample is liquid at room temperature, pour the sample into a glass colorimetric tube (5.1.1) to the 100 mL mark, let it stand at 20 °C for 24 h (48 h for castor oil), then place it in front of an incandescent lamp (5.1.3) (a white paper can be placed behind the colorimetric tube simultaneously) to observe the transparency and record the observation results.

5.2.2 When the fat and oil sample is solid or semi-solid at room temperature, melt the sample according to the melting point of the fat and oil, but the temperature shall not exceed the melting point by 5 °C. After the sample has melted, pour the sample into a glass colorimetric tube (5.1.1) to the 100 mL mark. Set the constant temperature water bath (5.1.4) according to the "transparency" specification in the product standard, place the colorimetric tube containing the sample in the constant temperature water bath, let it stand for 24 h, then place it in front of an incandescent lamp (5.1.3) (a white paper can be placed behind the colorimetric tube simultaneously). Quickly observe the transparency and record the observation results. NOTE. If there is no product standard, the temperature is set to the temperature at which the fat and oil sample completely melts.

5.3 Expression of results At the observation temperature, the results are expressed as "transparent", "slightly turbid", or "turbid". For example, transparency (20 °C). transparent. "Transparent" can also be expressed as "clear", "crystal clear", or "clear and transparent".

6.1 Instruments and equipment

6.1.1 Beaker. 100 mL.

6.1.2 Temperature-adjustable electric furnace. Voltage 220 V,

50 Hz, power less than 1000 W.

6.1.3 Thermometer. 0 °C ~ 100 °C.

6.2 Basic requirements for evaluating

6.2.1 Evaluating laboratory The evaluating room shall be well-ventilated, free from odours or residual smells, with a room temperature of 20 °C ~ 25 °C, no loud noise, sufficient light intensity, and soft colors, avoiding strong contrasts. The room or environment shall be kept quiet and undisturbed during evaluating.

6.2.2 Evaluator Evaluators shall possess keen sensory organs and identification abilities. Selection of evaluators shall be based on Annex A. During the evaluating, no communication is allowed, and the following shall be observed.

a) No smoking or eating one hour before evaluating, but water may be allowed;

b) At normal physiological state during evaluating, neither hungry nor overly full;

c) No use of cosmetics or other products with strong odours during evaluating;

d) Rinse mouth with warm water before evaluating to remove any residue.