Efficient and source-independent preparation of amyloid fibrils from almond protein isolates and concentrates

Amyloid fibrils generated from food proteins have been shown to be promising building blocks for designing functional materials and future foods. The formation of food amyloid fibrils usually requires the use of protein isolates, which largely hinders their practical application due to the high cost and environmental impacts for protein purification. In this study, we found that both almond protein concentrate (APC) and isolate (API) can be efficiently converted into amyloid fibrils by heating under acidic conditions. Atomic force microscopy (AFM), ThT fluorescence, ultracentrifugation measurements indicated that APC and API fibrils have comparable mesoscopic structures and conversion rate, analogous to whey protein isolate fibrils (the model system with excellent fibrillization property). The high fibrillization capacity of APC was demonstrated to benefit from its coexistence with sucrose. In fact, sucrose only slightly affected almond protein fibrillization even at high content of sucrose (60%). More importantly, the efficient fibrillization remained for APCs obtained from different sources, and can be scaled-up. Therefore, this study confirms for the first time the amyloidogenic property of almond proteins and paves the way for their practical utilization.