White asparagus stem proteins, from waste to interface stabilizer in food foams

Abstract

White asparagus stems are a large waste stream that, despite having a high nutritional quality, is currently underutilized. Plant waste stream utilization is often based on extensive processing, which uses copious amounts of resources, and can negatively affect protein functionality. Hence, our study aimed to explore alternative processing routes and characterize the effect of asparagus extract composition on interfacial and foaming properties.Screw pressing followed by mild purification methods was used to obtain and purify protein extracts from white asparagus stems. Mild purification by filtration removed particles and purification by dialysis removed molecular impurities. Removal of particles and molecular impurities led to improved interfacial properties, as shown with drop tensiometry. The particles disturbed interfacial network formation and the presence of small impurities reduced network density and in-plane interactions. Extracts without particles and molecular impurities formed a dense interface with stiff solid-like behavior and strong in-plane interactions, which resulted in superior foam stability. Additionally, foamability was improved after filtration and/or purification, which could be related to the air bubble size and adsorption rate.In this study, we identified critical factors for interface and foam stabilizing properties of asparagus proteins, and we revealed the great potential of mildly processed asparagus stem extracts for application in food foams.