LSE 9a (2Q): L1 - Rice Processing

staple foods

Food is in eaten in almost all diets that it became a part of our daily meals.

grain

Small, hard, dry seed, with/without an attached hull or fruit layer harvested for human and animal consumption.

grain-crop

Grain producing plants.

cereals and legumes

two main types of commercial grain crops

grain quality

Term that refers to the quality of grain, which depends on the use of the grain.

1. uniform moisture content

2. low percentage of discolored, broken, or damaged kernels

3. low breakability

4. high test weight

5. high milling quality

4. high protein and oil content

5. high viability

6. no aflatoxin

7. no foreign material

8. no presence of insects and molds

properties of grain quality

starch

The one that is fermented to get alcohol and a carbohydrate that provides dietary energy

rice (Oryza sativa)

Belongs to the genus Oryza of the subtribe Oryzinea in the family Gramineae and is a staple food in the Philippines. It also contains much starch and belongs to CEREALS (agronomic classification)

cereals

Grasses grown for their edible seeds.

long, medium, and short grains

3 main categories of grain crops

long grains

Relatively long and bold grains that are at least three times as long as they are wide when milled. They are separate, light and fluffy when cooked.

medium grains

Long, thin, cylindrical grains that have a creamy consistency when cooked. When milled, it has a length less than 3 times its width. It is moist and tender and has a tendency to cling.

short grains

Grains that are less than twice as long as they are wide and are soft and cling together when cooked. These are short translucent grains and can be easily picked up with a chopstick

paddy contents

Mature paddy contains 22% by weight of hull, 6% bran, and 72% endosperm.

hull

skin of the rice

brown rice

rice that the hull is removed and is not purely white because of the bran still intact

endosperm

the part of rice we commonly eat

rice post harvest practices

Practices that can affect rice grain quality, including environmental and handling conditions during ripening, harvest, post-harvest, and processing.

Includes:

1. using proper techniques of processing

2. using proper methods of harvesting

3. providing aeration to stored grains and stirring bulk grains occasionally

4. avoiding losses in threshing and winnowing by better mechanical methods

5. immediate drying of wet grains after 24 hours of harvest to avoid heat accumulation

6. using pest control measures before storage

7. prevention and control of fungi

parboiling

Procedure when palay is soaked in warm water, then steamed, dried, and milled to reduce breakage of grains during milling. It reduces breakage of grains when milling, improves nutrient content, and changes the grain's color aroma and taste.

milling

Removing of hull and husk from grain, which may also include removal of bran layer to produce edible white rice.

use of proper method of harvesting

always make sure that harvested palay grains should not be put on bare floor to avoid contamination and should be spread on mats tarpaulins and plastic sheets

bulking

- facilitates the process of threshing

- secures palay grains from rodents and other predators

- done properly = moisture goes down

- when raining unexpectedly = can be easily secured

threshing

- separating palay grains from rice straws

- should be done properly cus if not, it maybe mixed with other foreign materials

- should be done with mech threshers to be more hygienic

winnowing

- separating whole grains from other impurities

- uses weight property of grain

- letting air run thru grains and lighter grains are separated from heavy ones

- can have many loses since the force made by winnowing can also make other grains broken

traditional winnowing

kind of winnowing that uses plastic sheets, traditional mats and woven trays

drying

- process of removing excess moisture of grains, with delayed drying causing grain deterioration.

- paddy is being dried to the recommended storage and milling moisture content of 12-14% wet basis

mechanical and sun drying

two types of drying

mechanical drying

Expensive method that can guarantee a uniform drying among grains and does not depend on the weather conditions.

sun drying

More affordable method but can have longer drying time and depends on weather conditions.

moisture content

amount of moisture in an agricultural product and expressed as percentage of the original weight before drying

fumigation

- process of introducing volatile pesticide that exerts its toxin action in gaseous or vapour form.

- residual deposits on the treated surfaces will kill crawling insects and pests

fumigants

diffuses & penetrate to places where other forms of control are inadequate

bag stack spraying

layer by layer spray technique of fumigation and stack can last for 1 year for rough rice and 6 months for milled rice without insect infestation

whole stack is fumigated after spraying

1. rice weevil (Sitophilus oryzae)

2. khapra beetle (Trogoderma granarium)

3. red rust (Tribolium castaneum)

4. confuse flour beetle (Tribolium confusum)

insects that commonly infest rice grains

aflatoxin

Family of toxins produced by certain fungi that are found on agricultural crops, increasing liver cancer risk.

Aspergillus flavus

Aspergillus parasticus

main fungi present in aflatoxin and is abundant in warm and humid parts of the world

1. pre cleaning

2. hulling and husk aspiration

3. paddy separation

4. whitening

5. grading

rice milling operations

pre cleaning

Initial operation to remove foreign materials consisting of large impurities, small impurities, and impurities as large as size of grains.

It also makes use of sieves of diff sizes, blowers, and sifter using phys properties of grains like size

paddy separation

separation of unhulled palay from brown rice after hulling and

husk aspiration with paddy separator, then is returned to the huller for hulling and husk aspiration

paddy separator

makes use of difference in angle of repose of palay and brown rice

hulling

removal of the hull from the palay to produce brown rice by shearing action using under-runner disc or rubber roll

husk aspiration

separation of husk (light materials) from the brown rice and unhulled palay by blowing air and directing the husk into a cyclone for final discharge

whitening

removal of the bran layer from brown rice by scraping

vertical abrasion whitener, horizontal abrasion whitener, and friction pearler

3 main types of whitening

grading

separation of whole rice from broken rice using a rotating indented drum and grades based on the size of the grain

a. rough rice

b. brown rice

c. well-milled rice

d. parboiled rice

e. brewers/broken rice

f. head rice

different types of rice

Rough rice

Also called "PADDY RICE."

Pertains to individual rice kernels in natural and unprocessed state harvested directly from rice fields.

Brown rice

Also called "unpolished/cargo rice"

Only husk is removed while the bran layer remains, containing more nutrients than white rice.

Well-milled rice

Kernels fully polished and milled with husks and bran completely removed.

Parboiled rice

Rough rice that is soaked, pressure steamed, and dried prior to milling, modifying starch and retaining natural vitamins.

It is slightly yellowish but largely fades after cooking

Brewer's/Broken rice

Cracked rice kernels due to drying or milling, usually caused by moisture migrating too quickly within the kernel.

Head rice

Kernel with its length equal to or greater than 8/10 of the average length of the unbroken kernel.

Rice Based Products Examples

popped rice,

rice flakes,

puffed rice,

fermented rice cakes,

wet-milled rice cakes,

rice noodles,

rice papers,

bread from rice flour,

rice crackers,

rice muffins,

rice pudding,

baby food,

rice cereals,

rice starch,

rice tablets,

rice cakes,

canned/packed rice,

congee,

miso,

rice vinegar,

paella,

rice wine.