Course : Grain QualityModule 5 : Determining the Physical Characteristics of Milled RiceLesson 1 : What are the six physical characteristics of milled rice that determine quality?

Head Rice Recovery

High head rice yield is one of the most important criteria for measuring milled rice quality because broken grain has normally only half the value of head rice

% Brewer’s Rice

Brewer’s rice is often used as an ingredient for beer brewing, hence the name. In rural areas, brewer’s rice has a variety of uses and is commonly ground into rice flour.

% Damaged

Damaged rice kernels are those which are fully or partially darkened as a result of insect, mold, water, or heat damage. The presence of even a few damaged grain kernels can severely downgrade rice.

Course : Grain QualityModule 5 : Determining the Physical Characteristics of Milled Rice Lesson 1 : What are the six physical characteristics of milled rice that determine quality?

Attractive?

Under-milled rice is under-polished rice, or rice with bran streaks left in it. Under-milled rice does not store well because of high oil content of the residual bran. In addition, rice consumers almost universally desire well-milled rice because of its better appearance

Red/Red Streaked

Related to milling degree is the occurrence of red-streaked kernels; rice with part of the bran layer still sticking to the surface.

Chalkiness

If part of the milled rice kernel is opaque rather than translucent, it is characterized as chalky. Chalkiness disappears upon cooking and has no effect on taste and aroma. However, it downgrade the quality of milled rice.

Course : Grain QualityModule 5 : Determining the Physical Characteristics of Milled RiceLesson 2 : Measuring head rice recovery

HEAD RICE RECOVERY

1. Select 25 gram random sample of grain [A].

2. Using a grain grader separate the broken grain from the whole grains. For the calculation of the percentage of ‘brokens’ and the percentage of head rice recovery, a grain is considered to be a whole grain if it is 75% or larger of the grain.

3. Weigh the ‘brokens’ separated from the sample [B].

4. Compute the percentage of the ‘brokens’ [C] using the following equation:

5. Given the percentage of ‘brokens’, the percentage of whole grains can be calculated by subtracting the percentage of ‘brokens’ [C] from 100%. This is the percentage of head rice recovery

Wt of broken grains[B]X 100% Brokens[C]=

Wt of milled sample[A]

Course : Grain QualityModule 5 : Determining the Physical Characteristics of Milled RiceLesson 3 : What is brewer’s rice and how is it created?

Procedure

1. Using your scale, measure a 100 gram sample of milled grain [A].

2. Using the brewer’s rice sieve, select and separate the damaged grains from the sample.

3. Weigh the brewer’s rice separated from the sample [B].

4. Calculate the percentage of damaged grains in the sample using the formula:

Wt brewer’s [B]

wt of sample [A]X 100% brewer’s grains =

Brewer’s rice

BREWER’S RICE

Course : Grain QualityModule 5 : Determining the Physical Characteristics of Milled RiceLesson 4 : Which conditions damage rice grains and how does this affect the quality of rice?

DAMAGED GRAINS

Procedure

1. Using your scale, measure a 25 gram sample of milled grain [A].

2. select and separate the damaged grains from the sample.

3. Weigh the damaged grains separated from the sample [B].

4. Calculate the percentage of damaged grains in the sample using the formula:

Wt damaged grains [B]

Total wt of sample [A]X 100% Damaged grains =

Damaged grains

Course : Grain QualityModule 5 : Determining the physical characteristics of milled riceLesson 5 : What is chalkiness and how do you measure its presence in a sample of rice?

CHALKY GRAINSProcedure

1. Using your scale, measure a 25 gram sample of milled grain [A].

2. Separate the chalky grains with an SES scale of 9 (see table below)

3. Weigh the chalky grains (SES scale of 9) that you separated [B].

4. Determine the percentage of chalky grains using the equation:

Wt damaged grains [B]

Total wt of sample [A]X 100% Damaged grains =

Scale % area of chalkiness

0 None

1 Less than 10%

5 10-20%

9 More than 20%

A visual rating of the chalky proportion of the grain is used to measure chalkiness. The rating is based on the Standard Evaluation System [SES] scale:

Chalky grains

Course : Grain QualityModule 5 : Determining the Physical Characteristics of Milled RiceLesson 6 : What causes red and red-streaked grains and how does this affect the quality of milled rice?

RED AND RED-STREAKED GRAINS

Procedure

1. Using your scale, measure a 25 gram sample of milled grain [A].

2. Select and separate the red grains from the sample. The red grains are those that have 25% or more of the grain red.

3. Weigh the red grains separated from the sample [B].

4. Calculate the percentage of damaged grains in the sample using the formula:

Wt red grains [B]

Total wt of sample [A]X 100% Red grains =

Red grains Red-streaked grains

Course : Grain QualityModule 5 : Determining the Physical Characteristics of Milled RiceLesson 7 : Why is whiteness, translucency and milling degree important?

Procedure

1. Using your scale, weigh a 25 gram sample of milled rice. 2. Measure the grain whiteness using the whiteness meter.

The meter will return three values:

• Whiteness• Translucency• Milling Degree

3. Record the values for each of the three measures.

WHITENESS, TRANSLUCENCY AND MILLING DEGREE

Course : Grain QualityModule 5 : Determining the Physical Characteristics of Milled RiceLesson 7 : Why is whiteness, translucency and milling degree important?

WHITENESS, TRANSLUCENCY AND MILLING DEGREE

Whiteness

Whiteness is a combination of varietal physical characteristics and the degree of milling.During the whitening, the silver screen and bran layer of the rice is removed

Translucency

is determined by the clarity of the endosperm

Milling Degree

is determined by the amount of bran removed from the rice

Course : Grain QualityModule 5 : Determining the physical characteristics of milled riceLesson 7 : Why is whiteness, translucency and milling degree important?

WHITENESS, TRANSLUCENCY AND MILLING DEGREE

Whiteness meter