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

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

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

ABSTRACT Deep-fat frying is susceptible to induce the formation of undesirable products as 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 to evaluate the quality of plantain chips from local producers in relation to 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 in Yaoundé. Quality parameters determined in this study were: fatty acid composition of the oils, determined by gas chromatography (GC) of free acid methyl ester; trans fatty acids, determined by Fourier transform infra-red spectroscopy; Tocopherols and tocotrienols as markers of nutritional quality were analyzed by High Performance Liquid Chromatography in isocratic mode. Free fatty acids and acylglycerols as markers of lipid hydrolysis were analyzed by GC of trimethylsilyl derivatives of glycerides. 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. Asparagine content 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 trans fatty acids were not detected. Soybean oils were partly hydrolysed leading to the formation of free fatty acids, monoacylglycerols and diacylglycerols. In both oils, 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. This is explained by the absence of asparagine in the raw plantains, the other acrylamide precursors being present. This study shows 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 usage for frying should be questioned. Considering that asparagine is the limiting factor for the formation of acrylamide in plantain chips, its content depending on several factors such as production parameters and maturity stage should be explored

Freeze-thaw stability of konjac glucomannane-potato starch gels: Stability from macroscopic to microscopic scale, using image processing

Freeze-thaw (FT) stability is often used to assess the ability of a gel to support the damage induced byfreezing; selected parameters such as drip loss, damage to structure etc can be used to assess the freezetolerance of a gel. Konjac glucomannan (KGM) is a very specific hydrocolloid able to trap 100 timesits weight in water; it has not been studied so far as an improver to enhance FT stability. The aim of the study was to show that the presence of a small quantity of konjac glucomannan (KGM)in potato starch suspension increased the stability of carvacrol antioxidant trapping. FT cycles wereused to accelerate the ageing of the product and to assess its stability. In addition to drip lossesdetermination, the stability of carvacrol trapping was evaluated by the quantification of carvacrol inthe syneresis liquid. Microscopic and macroscopic scales were considered with microscopy. Themoment of the addition of carvacrol and the presence of KGM both had an effect on the stability ofcarvacrol trapping and of the structure of the gel. KGM promoted amylose retrogradation but sloweddown amylopectin retrogradation. The stability of potato starch gels can be improved by the addition of a small quantity of KGM, which showed a "cryoprotectant" behaviour. New method to characterizethe micro and macrostructure from SEM images processing has also been proposed. The processing ofmicroscopy images was done using Generalized Fourier Descriptors and allowed the characterization of each sample. The carvacrol addition lowered the physical stability of the gel with larger pores and increased syneresis. On the contrary, the KGM addition increased the size of the pores but preventedthe formation of very large pores and reduced syneresis. The most stable system was obtained by theaddition of carvacrol at the end of heating, in a konjac glucomannane potato starch gel. © 2018 International Institute of Refrigeration. All rights reserved