Deterioration of lipids in stored wheat grains by environmental conditions and fungal infection ‒ A review

During the storage of wheat grains and flours, a natural deterioration occurs due to aging over time, which is accelerated by adverse conditions of temperature and humidity that cause the growth of fungi. The local climates and infrastructure available for storage affect the preservation and duration of the safe storage time. Wheat lipids are a minor component, whose level and composition are decisive in the quality properties of wheat final products. Lipids are easily degraded, which is the main cause of quality loss. The enzymatic degradation of lipids is carried out by the activation of endogenous and/or fungal enzymatic activities, which produces hydrolytic and oxidative rancidity. Fusarium, Aspergillus, Penicillium and Alternaria are the most frequent genera found in infected grains. Wheat infection by Fusarium spp. is associated with considerable economic losses in crops throughout the world. The volatile compounds produced by oxidative rancidity are the main indicators of deterioration. Lipid rancidity must be monitored periodically using a combination of different analytical methods, ranging from traditional to modern alternative techniques of varied scope. Sensitivity to lipid deterioration varies with the wheat cultivar genotype, thus the selection of cultivars with better stability allows to obtain better quality products. In addition, a large proportion of the harvested wheat is usually stored for a long time until use, so achieving suitable environmental conditions and applying control measures prevent quality loss. This review updates the knowledge about wheat lipids, the importance of preserving their integrity during storage, presenting different monitoring alternatives to detect their rancidity, which would allow better decision-making.