Fat and Fatty Acid Concentrations in Some Green Vegetables

Petroleum ether is the solvent recommended by AOAC for fat determination using the Soxhlet method. However, hexane has also been used for defatting and for analysis of fat, lipids, and fatty acids in oil seeds, cereals, milk, and vegetables. This study compares the concentrations of fat and fatty acids in some green vegetables extracted by hexane or petroleum ether. Fat in dried cabbage, collard, purslane, peanut, and sweetpotato greens was extracted with hexane or petroleum ether by the Soxhlet method. Fatty acids in the extracts of peanut and sweetpotato greens were converted to methyl esters and analyzed by gas chromatography. The percentage of fat was higher when hexane was used and ranged from 0.9 to 3.4% for hexane and 0.5 to 2.8% for petroleum ether on a dry weight basis. For each vegetable, some fatty acid concentrations varied according to the extractant used and palmitic, linoleic, and linolenic acids generally had high values.