RICE MILLING AND PROCESSING

Introduction

Rice milling is a process which involves the removal of husk from paddy to get brown rice which is later polished to get white rice. This can be done both on small scale (traditional method of husk removal) and large scale (done by modern machines)

Small Scale or traditional milling
This involves the slow beating or hitting paddy in a mortar using a pestle. The mixture is then winnowed to get rid of husk and remain with brown rice. In traditional method, there is no polishing and rice is meant for domestic consumption.

Large Scale or commercial milling
This involves the use of modern machines
•    Single or one stage mill
•    Beehive machine milling-a series of machines

Single or one stage mill
•    One unit machine
•    All milling machines are combined in series under one unit.
•    This involves the husk removal section, husk separator section and the polishing section.
•    The machine doesn’t sort or grade the rice after polishing.
•    Meant to help farmers mill rice for domestic consumption and for informal market.

Beehive Machine milling
This involves a series of machines arranged singly for specific functions.
•    Removal of husk
•    Polishing
•    Sorting and blending
•    Colour sorting
•    Packaging

Rice is sorted and blended into grades as per the KEBS (Kenya Bureau Standards) manuals.
Rice is for commercial or large scale (sale).
Rice traded on formal market.

Quality of paddy to be milled
•    Well matured-exceeding 90% mature grain
•    Free from impurities (chaff, mud balls, stones and paddy straws).
•    Potential milling moisture content of 14%.
•    Pure to variety (no mixing of varieties.
•    Free from internal cracks
•    No fermented grains
•    Free from weed seeds

Grading of rice
The blending is done as per the Kenya Bureau of Standards (KBS) manuals. The packaging can be in denominations of 1kg, 2kgs and 5kgs.
•    Grade 1 -85% HR(whole grain) and 15% broken rice
•    Grade 11-75% HR and 25% broken rice
•    Grade 111-65% HR and 35% broken rice
The rest is packaged as broken rice.

Reasons for drying paddy at moisture content of 14%
•    Be safe for storage
•    Be safe for milling

Pre-planting

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Seeds of high quality should be true to its kind or variety, contain a minimum of impurities and have high establishment rates in the field. The main criteria for describing seed quality can be considered under the following:

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Growth

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There are five parts in understanding good land preparation. These components are an understanding of the:

  1. role of tillage and land leveling in land preparation
  2. reasons why good land preparation is important

Postharvesting

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Guidelines to proper harvesting:

  • Harvest at the right time with the right moisture content;
  • Avoid delays in threshing after harvesting;
  • Use proper machine settings when using a threshing machine;
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