Potential nutritional and functional improvement of extruded breakfast cereals based on incorporation of fruit and vegetable by-products: a review

Background: There is a need to improve the nutritional and functional characteristics of breakfast cereal products (BCP) consumed worldwide, namely by increasing the content and diversity of dietary fibre and enrichment in micronutrients and bioactive compounds. Considering the high amounts of fruit and vegetable by-products (FVB) generated by industrial processing, the associated environmental issues but also their richness in nutrients and phytochemicals, FVB show great potential for incorporation in BCP, thus improving the nutritional and functional aspects of these products. Scope and approach: The transformation of FVB into flours/powders results in added-value ingredients rich in fibre and bioactive compounds (e.g., phenolic compounds, carotenoids, prebiotics). The extrusion processing (used to produce BCP) is an affordable technique that uses flours as raw material. This work reviews extrusion processing to produce BCP supplemented with FVB powders and discusses the main effects on the final products associated with composition and processing characteristics. Additionally, advantages and challenges of introducing FVB powders into BCP are also reviewed and discussed. Key Findings and Conclusions: The use of the FVB flours to create richer BCP in several types of fibre and phenolic compounds appears to be a promising strategy to create nutritionally valuable BCP. By simultaneously valorising FVB, this strategy also contributes positively to the food system sustainability from a circular economy point of view. The use of FVB flours may improve fibre, micronutrient, and bioactive compounds content. High fibre content reduces texture quality of products, but extrusion processing allows to adjust production variables to overcome the potential decrease in sensory quality.