Fatty acid composition of oils from green coffee beans from different agro-ecological zones of Uganda

Abstract

Coffee is an important agricultural commodity and beverage widely consumed throughout the world. Two-thirds of Ugandans depend on coffee as an important source of income. The quality of coffee determines the relative price and its end use. The lipid composition has been used to characterize Arabica and Robusta coffee. Oil yield, fatty acid (FA) composition and oil nutritional quality of green coffee beans; arabica coffee (Coffea arabica) from Bugisu, Rwenzori, Kisoro and Maracha, and robusta coffee (Coffea canephora var. robusta) from Iganga, Ibanda, Rukungiri, Mbarara, Ntungamo, Masaka, Kayunga and Luwero coffee regions of Uganda were determined. Green coffee beans were obtained from Uganda Coffee Development Authority (UCDA) and coffee dealers in Iganga, Luwero, Kisoro and Maracha Districts. Oil was extracted in a Soxhlet apparatus using n-hexane. Fatty acids were determined as the FA methyl esters (FAME) using flame ionization detection gas chromatography. Differences in oil yield were analysed by ANOV A. The PUF A/SaF A, MUF A/SaF A, (PUF A +MUF A)/SaF A and PUF A/MUF A ratios were used to evaluate the nutritional quality of the oil. Oil yield ranged between 1. 75 and 15 .45%. Arabica coffee from Bugisu gave a significantly (p < 0.05) higher oil yield. Robusta coffee from Ntungamo gave the lowest mean oil yield. Unsaturated fatty acids (UFA) predominated over saturated fatty acids (SaFA). Linoleic and oleic acids were the main unsaturated fatty acids accounting for 53% of the total. Palmitic acid was the major SaFA. Oil yield and FA composition were dependent on agro-ecological coffee sample source and coffee variety. Based on the obtained nutritional quality indices, green coffee oil can be used in foods on blending with other oils. Nevertheless, there is need to investigate the existence of the transfatty acids in green coffee oil. KEY WORDS: Coffea arabica, Coffea canephora, fatty acid, green coffee beans, oil yield