TABLE OF CONTENTS
Title page
Dedication
Acknowledgements
List of Tables
List of Figures
Table of Contents
CHAPTER ONE
1.0 Introduction
1.1 Objectives of this Study
CHAPTER TWO
LITERATURE
REVIEW
2.1 Origin
of Rice and Distribution
2.2 Rice Taxonomy and Botany
2.3 Nutritive Value of Rice
2.4. Utilization
of Rice
2.5 Ways in
Which Rice Is Prepared
2.6 Rice processing
2.6.1 Rice milling
2.6.2 Parboiling
2.6.3 Small scale milling – the system approach
2.7 By-Product Utilization
2.8
Physical Properties
2.8.1
Grain Quality
2.8.2
Grain Dimension
2.8.3
Thousand Grain Weight
2.8.4
Shape
2.8.5 Density
2.8.6 Porosity
2.8.7 Angle of
Repose
2.8.8 Coefficient
of Friction
2.9 Importance of Physical Properties of Rice
CHAPTER
THREE
MATERIALS
AND METHODS
3.1 Source
of Raw Material
3.2 Sample
Preparation
3.3 Moisture
Determination
3.4 Physical
Properties
3.4.1 Size
Characteristics
3.4.2 Geometric Mean Dimension (De)
3.4.3 Sphericity and Aspect Ratio
3.4.4 Thousand
Grain Weight
3.4.5 Surface
Area (sa)
3.4.6 Determination of Bulk Density
3.4.6.1 True Density
3.4.7 Porosity
3.4.8 Angle
of Repose
3.4.9 Static
Coefficient of Friction (μ)
3.10 Statistical
Analysis
References
CHAPTER ONE
INTRODUCTION
Rice
(Oryza sativa L.) is one of the
important cereal crops cultivated worldwide. It is a source of food for about
two-thirds of the world population (Zhout et
al., 2002). It is a daily food for over 1.5 billion people. It is utilized
mostly at the house hold level where it is consumed as boiled or fried with
stew as in Nigeria. Different cultures have different preferences regarding the
taste, texture, colour and stickiness of the rice varieties that they consume.
For example dry flaky rice is eaten in south Asia and the Middle East; moist
sticky rice in Japan. In India, rice is consumed in various forms like whole
cooked grain and dish meal. It is served normally in two ways, white rice and
parboiled grains. Rice is used to produce many indigenous fermented food
products (like idli, dosa, uttapam, sake-
an alcoholic beverages) sweets (anarasa,
khir), kchichadi, pulav, puffed and extruded products (Ghadge and Prasad,
2012).
The marketing values of rice as an
agricultural product depend in its physical qualities after the harvesting. The
percentage of whole grain is the most important parameter for the rice
processing industry (Marchezan, 1991). Improperly designed and adjusted rice
processing machine may produce large quantity of broken rice kernel with
consequent low marketing value. To prevent this knowledge of the physical
properties of rice is of fundamental importance during the harvesting of
grains, transporting and design, manufacturing and operating different
equipments used in post harvesting processing operations of these products
(Ghadge and Prasad, 2012).
The porosity and specific gravity
are important for studies involving heat and mass transfer and air movement
through the bulk grain. The specific gravity could be defined as the ratio of
the mass of a body to its volume. This concept applied to the individual grain,
it determines the real specific gravity of the individual grain. When this
concept is applied to the bulk grain determines the bulk density. According to
Mohsenin (1986), porosity is defined as the ratio of the inter-granular void
space volume and the volume of the bulk grain.
Several
authors through the years have pointed out the need for knowledge of other
physical properties. For example, the static and dynamic friction coefficients,
such as grains on the equipment wall and on the silo wall surfaces are
necessaries and fundamentals for a rational and safe design of grain moving,
processing and storage equipment. (Lawton, 1980; Milani, 1993; Ghadge and
Prasad, 2008a; Mohsenin, 1986; Suthar and Das, 1996). This property develops an
important role on silo wall pressure and grain flowing behaviours. The friction
coefficient is defined as the ratio of the friction forces (forces due to the
resistance of movement) to the normal force on surface of the material used in
the wall. For biological products, according to Mohsenin (1986), two types of
friction coefficient are considered; the static coefficient determined by the
force capable to initiate the movement and the dynamic coefficient determined
by the force needed to maintain the movement of the grains in contact with the
wall surface which depends on the type and nature of the material in contact.
Consumers’
choice of rice varieties are largely based on physical properties. Rice quality
differs according to the variety and processing method use (pomeranz, 1992).
Traditionally, Ebonyi Farmers are rice producers, growing many varieties. The biotechnology
research centre, Ebonyi State University, Abakaliki have introduced new hybrid varieties
with better grain yield. The physical
properties of the new hybrid varieties introduced into the State have not been
studied. Therefore, there is need to assess the physical properties of new
varieties so as to design a machine suitable for handling, dehulling, and other
processes involved in the field of post harvest technology. This basic
information is of value not only to engineers but also Food Scientists,
Processors of plant and animal breeders etc.
1.2 OBJECTIVES OF THIS STUDY
The broad objective of this study
shall be to determine the physical properties of the selected rice varieties
grown in Abakaliki, Ebonyi State.
The specific objectives of the study
shall be to determine:
1. The dimensions and dimension related
properties.
2. The
weight and weight related parameters of rice.
3. The angle of repose, and static
coefficient of friction.