MODIFICATION AND PERFORMANCE EVALUATION OF A TEMPERATURE CONTROLLED RICE PARBOILER

Background of the Study
Rice ((Oryza spp.) is the world’s most important staple food crop consumed by more than half of the world population as represented by over 4.8 billion people in 176 countries with over 2.89 billion people in Asia, over 150.3 million people in America and over 40 million people in Africa. In Nigeria, the demand for rice has been on the increase since the mid 1970 Houssou, et al., (2004). During the 1960’s, Nigeria had a per capita annual rice consumption of 3 kg which increased to an average of 18 kg during the 1980’s, reaching 22 kg in the latter half of the 1990’s. Since the mid-1980’s, rice consumption has increased at an average annual rate of 11% with only 3% explained by population growth. Also, within the decade of the 1990’s, reported a 14% annual increase in the demand for rice in Nigeria.
An interesting reason for it being so popular, nutritionists suggest is its ease of digestion. Even the sick, elderly and babies can digest this grain very well if cooked. Even people who are allergic to lots of other foods can eat rice. Besides, rice provides 21% of global human per capita energy and 15% of per capita protein. It is low in fat and protein, compared with other cereal grains. Recent studies by the modern nutritionists have compared the easily digestible organic rice protein, a highly digestible and non-allergenic protein to mother’s breast milk in the aspect of its nutritious quality and also for the high quantity of amino acid that is common in both rice protein and breast milk. Rice also provides minerals, vitamins and fiber. Although, all constituents except carbohydrates are reduced by milling. No matter how plausible the reasons by nutritionist for rice consumption, they do not explain the increasing demand for rice in Nigeria (Graham, et al., 2015).

Parboiled rice is rice that has its starch partially gelatinized by soaking paddy rice or brown rice in water followed by steaming and a drying process. A major reason for parboiling rice in sub-Saharan African (SSA) countries is to reduce grain breakage during milling although it has also been shown that the water- soluble minerals and vitamins content of parboiled rice are higher than that of non-parboiled rice. Parboiling increases grain translucency and decreases chalkiness due to starch gelatinization. It also increases grain hardness and manages to reduce grain breakage as a result of the swelling of the starchy endosperm during gelatinization, which heals the pre-existing defects. In many SSA countries, artisanal methods of parboiling using diverse rudimentary equipment and procedures are common. In these countries, improving the artisanal parboiling process is a key component of national programs targeted at improving local rice quality. Focal activities in these programmes involve understanding the technicalities in the parboiling process from paddy cleaning through optimum parboiling, drying and milling Bhattacharya, (2004).

1.1 Statement of Problem
Rice is a staple food eaten all over the world. Good quality rice needs to be made available steadily, since half of the world population subsists wholly or partially on it. This is achieved by first parboiling the rice before it is milled. The local parboiling method used by rural farmers makes this process take a very long period of about twenty hours or more, and this consequently minimizes the milling quality of the rice. This has led to the development of modernized parboiling machines. Some of the already existing rice parboilers lack a means of temperature control and this consequently reduces the efficiency of the parboilers.

1.3 Objectives of Study
The general objective of the study is to modify an already fabricated rice parboiler and carryout its performance evaluation after modification. While the specific objectives are to:
I. Incorporate the temperature controlled device.
II. Drastically reduce the long period it takes to parboil paddy rice.
III. Improve the output efficiency of the already fabricated rice parboiler which can be verified by carrying out a performance evaluation after modification.
1.2 Justification of the Study
It is expected that the success of this research work will help in the formulation of adequate controlled techniques for paddy rice parboiler.

1.3 Scope of the Study
This study deals with the modification and performance evaluation of a temperature controlled rice parboiler.