A ¿GREEN PATH¿ STRATEGY FOR COMPLETE RECOVERY OF BUCKWHEAT PROCESSING BYPRODUCTS

This PhD thesis fits in the general framework of the so-called “circular bioeconomy” and focuses on the valorization of buckwheat husk, an agro-industrial by-product generated during the milling process. The main objective of the work was to identify and develop innovative strategies for the reutilization of buckwheat husk, thereby contributing to the reduction of food waste and the establishment of more sustainable and resource-efficient production systems. This work aligns with one of the key priorities of the European Green Deal, namely the efficient and responsible utilization of food by-products and food waste. Throughout the three-year research period, the possible end uses of this by-product—containing interestring bioactives compounds, was investigated with the aim of promoting its sustainable reuse. The main research outcomes can be summarized as follows: 1. A green extraction approach - based on microwave-assisted extraction (MAE)- was set up to improve recovery of the phenolics from buckwheat husk. The protocol developed here increased by 43.6% the polyphenols recovery compared to conventional techniques. 2. Buckwheat husk was evaluated as a natural filler in biocomposite materials. By combining enzymatic action with a microwave-assisted treatment, an enhanced cellulose accessibility was achieved along with complete retention of the original antioxidant activity, making the resulting material of interest for bioactive packaging applications. 3. Buckwheat husk was utilized as a substrate for solid-state fermentation (SSF) with the edible mushrooms Pleurotus ostreatus and Ganoderma annularis. Fungal growth improved the nutritional and functional profile of the husk, increasing its content in soluble dietary fiber and its proteolytic activity. 4. Mixtures of husk and either mushroom biomass were successfully incorporated into bread formulations (at a 10% substitution level), without compromising technological performance. The SSF-derived ingredients show promise for the development of baked goods with a decreased glycemic index. Overall, this research demonstrates the multifunctional potential of buckwheat husk as a sustainable material and functional ingredient, contributing to the advancement of resilient, circular, and sustainable food systems.