Food by-products and food wastes: are they safe enough for their valorization?

Background: Reduction of food waste provides important environmental and economic benefits. Valorization of food by-products into edible materials is one of the most interesting strategies in this field. However, food byproducts and wastes can contain chemical contaminants or potential pathogens that may endanger consumers' health. Therefore, assuring quality and safety of these by-products is of utmost importance to take advantage of this valorization strategy. Scope and approach: In this review, safety evaluation of valorized by-products intended for human and animal consumption has been revised and critically discussed. With this aim, the most relevant applications of valorized by-products intended for livestock feed or food, nutraceutical, and pharmaceutical industries, in which quality and safety were assessed have been compiled. Moreover, the most common strategies for the analysis and removal of undesirable substances in these valorized by-products have been pointed out, as well as the requirements established by current regulations. Key findings and conclusions: Despite the great number of applications found on food by-products valorization, only in a reduced number of works safety evaluation studies, such as physicochemical and microbiological assessments or the determination of toxic contaminants, were carried out. Among them, the development of decontamination procedures and processing approaches that avoid the generation of such undesirable substances, as well as effective analysis methods have been reported. However, in most cases the evaluation of results has been very complex and difficult due to the lack of specific legislation that regulates the suitability and safety of the new products to guarantee consumers' safety.