Effect of intermittent frying on fatty acids, vitamin E, lipid oxidation and acrylamide in oils and plantain chips collected from small- scale producers in Cameroon

International audience

إنجليزي. Deep-fat frying is susceptible to inducethe formation of undesirable productsas lipid oxidation products and acrylamide in fried foods. Plantain chips produced by small-scale producers are sold to consumers without any control. The objective of this study was toevaluate the quality of plantain chips from local producers in relationto production process parameters and oils, and to identify the limiting factors for the production of acrylamide in plantain chips.Samples of frying oils and plantain chips prepared with either palm olein or soybean oil were collected from 10 producers inYaoundé.Quality parameters determined in this study were: fatty acid composition of the oils, determined by gas chromatography (GC) of free acid methyl ester; transfatty acids,determinedby Fourier transform infra-red spectroscopy; Tocopherols and tocotrienols as markers of nutritional quality were analyzed by High Performance Liquid Chromatography in isocratic mode.Freefatty acids and acylglycerols as markers of lipid hydrolysis were analyzed by GC of trimethylsilyl derivatives ofglycerides. Conjugated dienes, Anisidine value and viscosity as markers of lipid oxidation and thermal decomposition of the oils;acrylamide which is formed through Maillard reaction and identified as a toxic compound in various fried products. Asparaginecontent of the raw fresh plantain powder was also determined.Fatty acid composition of palm oleins was stable within a day of intermittent frying. In soybean oils, about 57% and 62.5% of linoleic and linolenic acids were lost but transfatty acids were not detected.Soybean oils were partly hydrolysed leading to the formation of free fatty acids, monoacylglycerols and diacylglycerols. Inbothoils,tocopherols and tocotrienols contents decreased significantly by about 50%. Anisidine value (AV) and polymers contents increased slightly in fried palm oleins while conjugated hydroperoxides, AV and polymers greatly increased in soybean oils. Acrylamide was not detected in the chips. Thisis explained by the absence of asparagine in the raw plantains, the other acrylamide precursors being present. This studyshows that the plantain chips prepared at the small-scale level in Yaounde with palm olein are of good quality regarding oxidation and hydrolysis parameters and the absence of acrylamide. In contrast, oxidation developed with soybean oil whose usagefor frying should be questioned.Considering that asparagineis thelimiting factor for the formation of acrylamide in plantain chips, its content depending on several factorssuch as production parameters and maturity stageshould be explored.