GRADE QUALITY OF DOMESTIC RICE VARIETIES SOLD IN THE SOUTH-EAST ZONE OF NIGERIA. *1Azuka, C .E., 1Nkama, I. and 2Danbaba, N. 1DEPARTMENT OF FOOD SCIENCE AND TECHNOLOGY, UNIVERSITY OF NIGERIA, NSUKKA. 2NATIONAL CEREALS RESEARCH INSTITUTE (NCRI), BADEGGI, P.M.B.8 BIDA, NIGER STATE, NIGERIA *email@example.com
INTRODUCTION • Grading in rice processing is a process in which the head rice is separated from broken rice using grain graders and improved technologies. • High head rice yield is one of the most important criteria for measuring milled rice quality as broken grains have normally only half of the value of head rice. The value of broken rice is 30 to 40% as high as the value of whole kernels. • Grading is carried out in many industrial rice mills with advanced technologies. These include in drum graders, plansifters and indented cylinders working at different stages .
Table 1: Grade Characteristics Source: Semple et al., 1992
STATEMENT OF PROBLEM • Limited studies have been conducted on the quality characteristics of domestic rice varieties sold in Nigeria. The grade quality of domestic rice varieties sold in Nigeria has not been fully investigated. • OBJECTIVE OF THE STUDY • The objective of this study was to determine the grade quality of parboiled milled domestic rice sold in the South-East zone of Nigeria.
MATERIALS AND METHODS • Eighteen (18) varieties of domestic rice were collected from Adani rice mills and Ikpa market in Enugu state; Omor and Ogboji-Ekwulobia in Anambra state; Afikpo and Abakiliki rice mills in Ebonyi state, Nigeria. Three (3) imported rice varieties were purchased from Ogige market in Nsukka LGA of Enugu state, Nigeria. The imported rice varieties were coded controls 1, 2 and 3. • The samples collected were cleaned by winnowing using plastic trays to remove husk and shrivelled kernels (defectives).
Ten (10) grams of the cleaned milled rice of each variety were selected and graded. • The head rice were separated from the brokens by hand-picking method. • The weights of the broken and head rice grains were determined using an electronic pocket scale (model EHA251). • The percentage values for the head rice and broken rice were calculated using the expressions below: • % Head rice = Wt. of whole grains x 100 • Wt. of sample used
% Brokens = Wt. of brokens x 100 Wt. of sample used
RESULTS AND DISCUSSION • Table I shows the grade quality of the rice varieties obtained from the different locations. • There was no significant (p>0.05) difference in the broken and head rice value of imported rice varieties. The imported rice varieties were of premium quality grade. • Significant (p<0.05) differences existed in the head rice and brokens of imported rice varieties and a large percentage (77.78%) of the domestic rice varieties.
Table I: Head rice and broken rice values of domestic rice varieties sold the South-East zone of Nigeria. * Means in the same column carrying similar superscript are not significantly (P>0.05) different
The rice varieties from Enugu state excluding Fortin 16 (old variety) were of grade 1 quality. • Faro 40 and Taraba rice from Anambra state were of grade 2 quality while R-Bus, Igboukwu rice, Aguleri rice and B-G were of grade 1 quality. • Geshua from Ebonyi state was of grade 2 quality while Afikpo-Mas, Abakiliki-Mas, R-8 and 306 were of grade 1 quality.
Only Omor-Mas, Akpujie, kpurukpuru and Fortin 16 (old variety) met the criteria for premium quality • Large percentage (88.89%) of the domestic rice varieties excluding Akpujie and Kpurukpuru from Abakiliki had significant (p<0.05) high brokens.
High broken in milled rice reduces the quality of the milled rice lot. This is seen in most of the domestic rice varieties which had high brokens being of grade 1 quality and some of them of grade 2 quality. • From the Table, it can be inferred that nearly 100% (94.4 %) of rice mills in South-Eastern zone of Nigeria do not grade parboiled rice after milling. This is the result of the high brokens in domestic rice varieties along with production factors. The mills do not have any equipment for grading of milled rice lot.
Non-grading of milled rice is as a result of absence of grain graders in all the rice mills visited. • CONCLUSION • Grading as a unit operation should be incorporated in rice mills in Nigeria in order to obtain high head rice yield. • Grain graders should be provided for all rice mills in Nigeria in order to improve the grade quality of the domestic rice varieties and meet international standards.
REFERENCES Web, D. B. and Stermer, R. A. (1972). Criteria of rice quality. In: Rice Chemistry and Technology (Houston, D. F., ed.). American Association of Cereal Chemists, Incorporated St. Paul, Minnesota. pp.102-139 Nkama, I., Kassum, A. L. and Jato, A. A. K (2011). Rice processing in Nigeria. Publication of the Intellectual Property and Technology Transfer office, University of Maiduguri, Maiduguri, Nigeria. Semple, R. L., Hicks, P. A., Lozare, J. V., and Castermans, A. (1992). Towards integrated commodity and pest management in grain storage. http://www.fao.org/docrep/x5048e/x5048e03.htm