ISO 14864 pdf download.Rice — Evaluation of gelatinization time of kernels during cooking
1 Scope
This International Standard specifies a method of evaluating the gelatinization time of rice kernels during cooking. It is applicable to milled rice as defined in ISO 7301 .
2 Normative references
This following normative documents contain provisions which, through reference in this text, constitute provisions of this International Standard. For dated references, subseqent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies. Members of IEC and ISO editions maintain registers of currently valid International Standards. ISO 71 2, Cereals and cereal products — Determination of moisture content — Routine reference method . ISO 7301 , Rice — Specification.
3 Terms and definitions
For the purposes of this International Standard, the terms and definitions given in ISO 7301 and the following apply. 3.1 gelatinization hydration process conferring the jelly-like state typical of the coagulated colloids, which are named “gels”, on kernels 3.2 gel state condition reached as a consequence of gelatinization (3.1 ), when the kernel is fully transparent and absolutely free from whitish and opaque granules after being pressed between two glass sheets See Figures 1 to 3. 3.3 gelatinization time time necessary for 90 % of the kernels to pass from their natural state to the gel state (3.2)
4 Principle
The time span is determined between the immersion of the kernels into boiling water and those kernels becoming fully gelatinized, evaluated by visual observation.
5 Apparatus
Usual laboratory apparatus and, in particular, the following. 5.1 Electric plate, able to maintain a constant temperature of 350 °C ± 1 0 °C. 5.2 Beakers, of borosilicate glass, of capacity 400 ml and diameter 8 cm. 5.3 Perforated spoon, of stainless steel, with a thermo-insulated handle. 5.4 Glass rod, about 25 cm long and 5 mm in diameter. 5.5 Round or square glass slides, about 70 mm in diameter or side length, and 5 mm thickness. 5.6 Balance, capable of weighing to the nearest 0,01 g. 5.7 Stop clock. 5.8 Worksurface, contrasting in colour to rice kernels. 5.9 Sample divider, conical or multiple-slot sampler with a distribution system. 5.10 Glass balls, of diameter of 5 mm.
6 Sampling
Sampling is not part of the method specified in this International Standard. A recommended sampling method is given in ISO 1 3690 [3]. It is important that the laboratory receive a sample which is truly representative and has not been damaged or changed during transport or storage.
7 Preparation of test sample
7.1 Carefully mix the laboratory sample to make it as homogeneous as possible. 7.2 Determine the moisture content of the sample according to ISO 71 2. The acceptable range is a mass fraction of (1 3,0 ± 1 ,0) %. If the moisture content is different from the above, condition the sample at ambient temperature and relative humidity until a moisture content within the specified range is obtained. 7.3 Reduce the laboratory sample, when necessary, using the sample divider (5.9) to obtain an amount of about 1 5 g. Discard all kernels with visible embryo (germ) residues and broken grains. Randomly select (1 0,0 ± 0,1 ) g from the remaining whole kernels as the test sample. 7.4 Prepare five test samples as described in 7.3.
8 Procedure
8.1 Place some glass balls (5.1 0) into the beaker (5.2). Add 275 ml of deionized water and place it on the electric plate (5.1 ). 8.2 Heat the water until boiling vigorously. 8.3 Pour one test sample (7.3) into the beaker, and, at the same time, start the stop clock. Stir with the glass rod (5.4) for a few seconds to prevent the kernels sticking to the bottom of the beaker.