Overview
ISO 14864:1998 specifies a laboratory method to evaluate the gelatinization time of rice kernels during cooking. Applicable to milled rice (as defined in ISO 7301), the standard defines how to determine the time required for kernel starch to reach the fully gelatinized “gel state” by visual inspection after cooking. The primary result is the t90 value - the time for 90% of kernels to become fully transparent and free of whitish opaque granules.
Key Topics and Requirements
- Scope: Method for milled rice; sampling itself is outside the method (see ISO 13690).
- Definitions: Gelatinization, gel state, and gelatinization time (t90).
- Sample preparation:
- Moisture content must be measured per ISO 712 and conditioned to (13.0 ± 1.0) % if necessary.
- Test sample: 10.0 ± 0.1 g whole kernels (no broken grains or germ residues); five replicate test samples.
- Apparatus (selected):
- Electric plate (specified to maintain 350 °C ± 10 °C),
- 400 ml borosilicate beakers (8 cm diameter),
- Glass slides, perforated spoon, glass rod, glass balls, balance (0.01 g), stopwatch, contrasting worksurface.
- Procedure (high level):
- Boil 275 ml deionized water with glass balls, add sample and start timing.
- Remove sets of ≥10 kernels at defined intervals (first at 7 min, then every minute).
- Flatten kernels between glass slides and visually assess the gel state; repeat until 10 kernels are fully gelatinized for two successive readings.
- Result calculation:
- Compute percent gelatinized for each time, average five replicates, perform paired averaging (double equalization), plot curve or use regression to interpolate t90.
- Express t90 in minutes and seconds.
- Precision: Annex B summarizes interlaboratory repeatability and reproducibility from trials.
Applications and Who Uses It
- Rice breeding and varietal screening - assess cooking quality traits.
- Quality control in milling and rice processing - monitor product consistency and cooking performance.
- Food science and R&D - study starch properties, texture and processing effects.
- Regulatory labs and standards organizations - provide reproducible, comparable gelatinization data for specifications and trade.
Typical users include cereal chemists, QC laboratories, rice research centers, food technologists, and commodity specification teams focused on rice gelatinization time, cooking quality, and rice testing.
Related Standards
- ISO 712 - Moisture content determination for cereals
- ISO 7301 - Rice specification (milled rice)
- ISO 13690 - Sampling of static batches (recommended)
- ISO 5725 - Accuracy (trueness and precision) of measurement methods
Keywords: ISO 14864, rice gelatinization time, milled rice, rice testing, cooking quality, t90, laboratory method.