Analysis of amaranthus oil from selected agro-ecological zones in Kenya
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Date
2012-03-28
Authors
Okoth, Kevin Otieno
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Abstract
Amaranthus is a pseudocereal that has its origin in Mexico, South America. It is commonly known as 'terere' in Kenya and is mostly used as leaf vegetable. It is fast gaining interest in Kenyan population as a grain due to its ability to adapt to different environments thus can be grown in semi-arid areas, its fast maturity time of 45-75 days, its high economic value and its vital nutrient composition. Amaranth is found to flourish in hot and dry climates where other cereals are difficult to grow. It also grows in diverse geographical areas. It is also recommended for those ailing from cancers, skin diseases, arthritis, allergies, diabetes, cardiovascular diseases and HIV and AIDS due to immune boosting properties of its composition. Very little is available on the quality of amaranth oil in Kenya. Therefore, the study set out to establish if the diversity affected the amaranth grain oil composition, quality and quantity. Four different regions namely: Bondo, Bureti, Kenyatta University and Nyeri were chosen and two species of amaranth:
Amaranthus cruentus and Amaranthus hypochondriacus were grown. The oils from the grains were extracted using soxhlet and Dyer and Bligh methods. Cold pressed oil was obtained for Meru and Embu regions from All Grains Company in Nairobi. The fatty acids composition were determined using gas chromatography and were identified by comparison with the RF of fatty acid standards injected under the same conditions while polar and neutral lipid composition was determined using thin layer chromatography. The study showed that there was statistically no difference in the composition of oil extracted from Dyer and Bligh method and that of cold pressing. The fatty acid profile for Amaranthus cruentus included: linoleic acid (35-38 %), oleic acid (32-36 %), palmitic acid (22-24 %), stearic acid (2-4 %) and linolenic acid (1-2 %). There was no significant difference in the composition of fatty acids in the selected regions. The fatty acid profile for Amaranthus hypochondriacus was: linoleic (41-44 %), oleic (26-34 %), palmitic (19- 24 %), stearic (2-3 %) and linolenic acid (1-3 %) with no significant difference being observed between the study regions.
This study reported capric, lauric, myristic, pentadecanoic, palmitoleic and heptadecanoic acids for the first time though in small amounts. The total lipid component ranged from (7-10 %) for Amaranthus hypochondriacus and (7-9 %) for Amaranthus cruentus. There was a significant difference in the iodine value of both Amaranthus hypochondriacus and Amaranthus cruentus when they were compared for the respective regions. Triacyglycerides were the major component of neutral lipids (73-83 %) while phosphatidylethanolamine (25-60 %) and phosphatidylcholine (15-35 %) were the major components of the polar lipids. The results of the study compared well with those done earlier in other countries. The results of the study will be used to sensitize the communities on the oil nutritional value of amaranth us. They will also be availed to relevant authorities for further action.
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Department of Chemistry, 96p. The SB 191 .A42O38 2009