Rice Quality Training Manual 06

Rice Quality Training Manual
2.0 Grain quality characteristics
Rice grain quality represents a summary of the physical and chemical characteristics that may be genetic or acquired properties.
The genetic properties include:

• chemical characteristics (gelatinization temperature, apparent amylase content, gel consistency, alkali spreading value and aroma),
• shape,
• size,
• color of grain,
• chalkiness,
• bulk density,
• thermal conductivity,
• equilibrium moisture content and
• flowability.
The acquired properties or environmental factors are either additional to the normal complement of genetic qualities or are the consequence of certain genetic qualities being lost or modified. The important acquired properties are:

• moisture content,
• grain purity,
• physical and pest damage, cracked grains,
• presence of immature grains and
• milling-related characteristics (milling and head rice recoveries, grain dimensions, whiteness, milling degree and chalkiness) will likewise be included.
Milling-related characteristics are relevant measures of value because these are the major concern of consumers. The quality characteristics of paddy and milled rice can be considered separately.