2012-01-16 mishra - grain storage methods and measurements

7/25/2019 2012-01-16 Mishra - Grain Storage Methods and Measurements

1/33

Grain Storage: Methods and Measurements

Dr H N Mishra

Professor & Programme Coordinator (Food Technology)President (P), Association of Food Scientists & Technologists (India)

[email protected]

Agricultural & Food Engineering Department

Indian Institute of Technology

Kharagpur 721302, India


2/33

Grains in India

2

Food grain production in the country grew atan average 1.98 % during 2004 to 2010,which was higher than the average rate of

population growth of 1.50 %

232.07 million tonnes production in 2010-11

10% storage losses.

60-70% of food grain produced in the countryis stored at home level in indigenous storagestructures.

Rest enters the urban market channel andpublic distribution system

1 February 2012 Professor H N Mishra, IIT Kharagpur


3/33

Rice WheatCoarse

CerealsPulses

Total food

grains

1950-51 20.58 6.46 15.38 8.41 50.82

1960-61 34.58 11 23.74 12.7 82.02

1970-71 42.22 23.83 30.55 11.82 108.43

1980-81 53.63 36.31 29.02 10.63 129.59

1990-91 74.29 55.14 32.7 14.26 176.39

2000-01 84.98 69.68 31.08 11.07 196.81

2010-11 94.01 81.47 40.08 16.51 232.07

3

Grain Production (million tonnes) in India



4/33

Moisture

Temperature

Insects and rodents

Quality before storing the grain

Type of storage bin

Use of pesticides and fumigants

Mechanical loss factors General condition of location of

storage.

4

Factors Affecting Grain Losses



5/33

Single most important factor responsible for thedeterioration in the quality of the food grain.

Reduction in 1% of moisture content will double the

shelf life.

Higher moisture and temperature, the faster thegrowth and more rapid the spoilage of grain.

At low enough moisture contents, all mold growthstops even at favourable temperatures.

5

Grain moisture



6/33

Commodity Moisture content

(% wet basis)

Paddy, rice (raw) 14

Rice (Parboiled) 15

Wheat, Bengal gram 12

Sorghum, maize, barley, ragi, bajra, pulse, turmeric,

wheat atta, maida besan

12.5

Coriander, chillies 10

Groundnut pods 6-7

Mustard seed 5-6

Upper limit of grain moisture content for safe storage

1 February 2012 6Professor H N Mishra, IIT Kharagpur


7/33

Temperature controls the activities of themicroorganisms and its effect is also correlated to themoisture present in the grain.

When grain in storage is cool, there is little likelihood of

spoilage. Low temperature offset the effects of high moisture,

particularly as it affects the development of molds andinsects.

One of the greatest benefits of moving and turning grainis cooling.

7

Temperature



8/33

The grains usually contain initial internal infestation as

well as field and storage fungi.

The temperature gradient and moisture migration mayinduce the initiation of due point and condensation of

moisture with in the bulk.

It may be responsible for high rate of respiration, mouldgrowth and threatened germination.

8

Storage environment



9/33

The insects accelerates their growth up to 42oC but fungi

have tolerance limit from 20oC to a maximum 63oC.

These environment have to be avoided for safe storagerequirements.

Fungi are the most dangerous and extremely harmful

enemy for the grain as they can not be seen with nakedeyes and their harmful influence spreads very quickly.

9

Insects and fungi



10/33

The storage structure should be

Elevated and away from

moist places

Airtight, even at loading andunloading ports

Rodent-proof & clean

Plastered with an

impervious clay layer toavoid termite attack, or

attack by other insects.

Steps to reduce losses



11/33

Points to remember for safe and scientific storage

Site selection

Storage structure

Cleaning and fumigation

Aeration

Regular inspection of grain stock

Storage Methods



12/33

12

Local

nameState

Material of

constructionShape Dimension Capacity

Khani or

Patra

Orissa

A.P.

Dug out with

sides plastered

with cow dung

Rectangular

D = 150 cm

Sides: 150-

200 cm

2-3 ton

Khai Rajastan

Well, lined with

stone / sand-

cement

Circular orrectangular

D = 600 cmDia = 600 cm

Upto 60ton

Indian TraditionalUnderground Storage Structures



13/33

13

Localname

State Material ofconstruction

Shape Dimension Capacity

Khothi

Bihar,

Punjab,

U.P.

Unburnt clay mixed

with straw and mud-

cow dung or brick and

masonary

Cylindrical

Rectangular

Varies in

diameter1-50 ton

KanagiMysore

and M.S.

Bamboo plastered

with clayCylindrical Varies in sizes 1-20 ton

KothaPunjab

and U.P.

Small shed built with

brick and masonary

CylindricalVary in sizes 5-100 ton

Indian TraditionalAbove-ground Storage Structures



14/33

14

Local

nameState

Material of

constructionShape Dimension Capacity

Dholi M.P.

Straw, bamboo,

palm leavesplastered with mud

and cow dung mix

Cylindrical Vary in sizes 2 ton

Thekka

Punjab,

U.P

Gunny or cotton

wound aroundwooden support

Rectangular

L = 240 cm

B = 390 cm

H = 210-330

cm

Upto

30 ton

Indian TraditionalAbove-ground Storage Structures



15/33

Crop umbrella:

A flexible PVC sheet covering (30-50

micron size), used if storage time is

short (2-3 weeks).

For 2-3 months storage periods,

Pusa bin

Coal-tar drum bin

Domestic Hapur Bin

Pusa bin

LDPE (low density polyethylene)

sandwiched bin. Moisture migration

during storage is minimal because of

the good insulation properties.

On-Farm Food Grain Storage



16/33

Pusa Bin



17/33

Low cost and easy

availability

Developed at the

Central Institute of

Agricultural

Engineering (CIAE)

Coal-tar Drum Bin



18/33

Developed by Indian Grain

Storage Institute

Made of galvanised iron

and/or aluminium sheets

Capacity 200 to 1000 kg

Domestic Hapur Bin



19/33

Food Corporation of India (FCI)

Central Warehousing Corporation

State Warehousing Corporation

Grain marketing co-operatives

State government agencies

Benefits:

Low running costs

Low labour requirements

Rapid handling

Low through spillage and rodents

Efficient and effective fumigation operation

Less land area requirement

Complete control of aeration

Possible to store the grain for longer periods

Possible to mechanize all operations

Possible to store moist grain for short periods

Bulk storage of food grains in India



20/33

Cover and Plinth Storage

Community Storage Structures

Rural Godowns

Silos

Bulk Storage of Food Grains in India



21/33

Grain stays warm without aeration



22/33

Ambient Aeration

A process of forcing air throughgrain to reduce its temperature inorder to preserve them fromdeterioration

Requirements:To provide some form ofperforated ducting on the floorthrough which air can be blowninto the grain, and

Venting above the grain for airexhaust

Refrigerated AerationAchieves much lower temperatureswhen ambient conditions are

warmRequirements:Same as for ambient aeration,except that no fan control isrequired since the system willoperate 100% of the time until thetemperature front has passedthrough the grain mass.

Relationship of storage

temperature and grain moisture

content

Aeration



23/33

Most insects cannot exist indefinitely

without oxygen or in conditions of

raised (greater than approximately

30%) carbon dioxide.

The required atmospheres can be createdeither by:

adding pure gases carbon dioxide or

nitrogen or the low oxygen exhaust of

hydrocarbon combustion, or

using the natural effects of respiration(grain, moulds or insects) to reduce

oxygen and increase carbon

dioxide Hermetic storage.

23

Controlled Atmosphere Grain Storage



24/33

What determines grain quality?

24

Genetic AcquiredChemical characteristics such as

gelatinization temperature, gel

consistency, and aroma

Moisture content

Grain shape and size Color and chalkiness

Bulk density PurityThermal conductivity Damage

Equilibrium moisture content Cracked grains

Immature grains

Milling-related characteristics (head

rice recoveries, whiteness and

milling degree) are also included as

relevant measures of quality

because they are of concern to

consumers



25/33

Major quality changes during storage

Loss/gain of weight

Changing of physical appearance

Loss of nutritional/food value

Loss of culinary properties

Total destruction of the grain



26/33

Grain quality measurement methods

Visual inspection

Machine vision system

Near-infra red (NIR) system

Chemical & microbiological analysis



27/33

Cracked, Immature & Discoloured Grains

Breakage occurs during harvesting and milling Immature grains do not survive the milling process

Grains can ferment if exposed to wet conditions

All measurements can be made by physical

counting or using appropriate instrumentation



28/33

Measuring foreign matters

Screens in sieves consist of perforated metal plate

(national or international standards organizations)

28

Nominal aperture

(mm)

Recommended

volume of load (cm)

Typical grain

equivalent

8.0 500 300g Maize

4.0 350 250g Sorghum

2.0 200 150g Wheat

1.0 140 100g Millet

(Source: International Standard ISO 2591-1973)



29/33

Moisture meter

Factors to be considered whileselecting a meter

Resolution

Repeatability

Reliability

Stability

Range of commodity

Range of mc

Sample size

Sample weighing

Ambient effect



30/33

Machine vision system

Statistical or artificial neural network classifiers for pattern recognition

To determine

varietal purity

class identification

impurities or foreign matters

grain kernel morphology

grain discoloration

stress cracks &

insect damaged kernels

Soft X-ray system - for stress cracks, hidden insect infestation & sproutedkernels

Transmitted light systems for stress cracks

Hardness testers - Susceptibility of breakage during handling



31/33

NIR-Spectroscopy

It is a rapid technique requiring small sample size

Replaced the chemical intensive Kjeldahl method

For measuring moisture, protein and oil content in grains

Also being investigated for

hardness and vitreousness of grain kernels

grain color classification

identification of damaged grain

detection of insect and mite infestation and

detection of mycotoxins



32/33

Conclusions

The indigenous storage structures are not suitable for storing grains for

long periods.

Thus, improved storage structures and scientific storage of grains in form

of warehouses is the need of the hour to strengthen traditional means of

storage with modern inputs and to provide cheaper storage to farmers so

as prevent enormous storage losses.

Over 420 standard test methods, including at least 75 internationally-

applicable methods, are available to test the quality of stored grains.

Of the wide range of properties used for testing, the bulk density and the

foreign matter are commonly assessed for most types of grains.

1 February 2012 Professor H N Mishra, IIT Kharagpur 32


33/33

14 January 2012 33Professor H N Mishra IIT Kharagpur

2012-01-16 mishra - grain storage methods and measurements

Documents