Page 27 - Vol.38-No.2

CROP PROTECTION

• Only use clean and dry (prefer-
ably new) jute or sisal sacks. This
avoids risk of contamination and
moisture absorption by the grain.
If grain is earmarked for transit to
a more humid zone then it should
be packaged in polythene sacks.
However, only optimally dry grain
should be packed in polythene
sacks, or paper sacks with poly-
thene liners. Polythene not only
Rice panicles packed with full, ripe stops moisture getting into the bag Small-scale rice-harvesting in Nigeria
grain and ready for harvest and but also any excess moisture in the (Picture courtesy Nick Ashton Jones)
processing (Picture courtesy Omex)
grain from getting out.
s 6WULFW FRQWURO RI VDFN RU EDJ ÞOOLQJ Be that as it may parboiled rice offers
Storage in well-aerated rooms avoids using accurate scales. a number of clear advantages over and
absorption of moisture leading growth • Well ventilated and insect and above untreated milled rice. Parboiling
of surface mould and grain discolour- rodent free storage conditions prior hardens grain and thereby decreas-
DWLRQ %XW URRPV PXVW EH VXIÞFLHQWO\ to retailing es susceptibility to breakage during
sealed to exclude insects, rodents and the de-husking process and damage
• Re-packing in paper packets for
birds. Provided these measures are im- by insect pests in store. In addition it
short-term storage and retail, and
plemented, threshed grain can be kept enhances the nutritional quality and
heat-sealed polythene for longer-
in good condition until milling. value of rice by promoting movement
term storage prior to retail.
of nutrients from the outer coverings
Quality control points Because the rice stays dry throughout (bran) and into the grain, so they
in primary processing, and does not undergo any pre-cooking are not removed in the bran during
sacking and storage or contact with water there is minimal de-husking. On the other hand oil in-
risk of contamination with pathogenic
Primary process control points dur- microbes. Standard hygiene practices side the grain moves out. The reduced
oil content lowers the risk of rancidity
ing milling are: in relation food production and han- and improves storage life.
• Maintenance of grain moisture GOLQJ DUH GHHPHG VXIÞFLHQW Mainstream parboiling methods use
at 12-14% w/w to facilitate optimum a soaking time of 1 to 3 days at an initial
de-husking (hulling) and storage The wet rice process ZDWHU WHPSHUDWXUH RI Ĺ& WKH PRUH
quality Par boiling is the pre-cooking of rice constant the temperature the shorter
• Select holding times for grain in in water prior to milling. This simple the soaking time with limitation on the
de-husking and polishing machines. process sets off and maintains a series development of off-flavours. The prod-
This ensures optimum balance be- of rather more complicated reactions uct is then steamed for 20 minutes at
tween level of grain breakage and in the grain. These positively alter the Ĺ& )LQDOO\ LW LV VXQ GULHG WR
per cent of de-husked grain in the grain’s physical, chemical and nutri- w/w moisture while carefully avoiding
ÞQLVKHG ULFH SURGXFW /HQJWK RI WLPH tional qualities in relation to both mill- extreme high temperature and peri-
in these machines also determines ing and eventual consumption. ods of wet weather. It is now ready for
whether the end product is white 3DUERLOLQJ oVWDUWHG OLIHp DV D oYLO- village scale de-husking/polishing or
rice or brown rice. Brown rice is lage-level’ technique then developing industrial milling operations.
de-husked less and is richer in the differently in various parts of the world Key process control points to look out
Vitamin B complex. according to custom, requirement and for during parboiling include:
Equivalent primary control points WKH GHVLUHG WDVWH DQG IODYRXU RI WKH ÞQ- • Grain to be soaked at a constant
during following packaging, storage ished rice product. As such, there is no Þ[HG WHPSHUDWXUH IRU D VSHFLÞF SHULRG
and marketing phases of post-harvest standard technique of parboiling rice of time to produce a consistently high
processing are: in relation to water temperature and quality product, and of a type required
length of the processing time. Parboil-
by local consumers
ing as the wet method of processing
rice for human consumption originat-
ed in Asia in but there was already a
strong tradition in West Africa of similar
treatment for other staples like cassava,
which is fermented during the produc-
tion of Gari.
Techniques in which the paddy rice
is steeped in hot water for a long time
impart a strong flavour and yellow col-
our to the product. In other areas where
these characters are not required, the
Successful rice crop growth and paddy rice is simply boiled until the
development for which the rewards husks burst, after which the product is A rice grain cleaning system
will come with the rice harvest(Picture dried. This technique only partly ge- constructed in Africa by Alvan Blanch
courtesy Nick Ashton Jones) latinizes starch in the rice grains so the (Picture courtesy Alvan Blanch)
grains are not fully hardened.
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Vol. 38 No. 2