# Unveiling the potential of beetroot leaf as a sustainable source of proteins: insights into ultrasound-assisted extraction, functional properties and in vitro digestibility

## TL;DR

Beetroot leaves, usually thrown away, can be a good source of plant-based proteins using a new extraction method that improves quality and digestibility.

## Contribution

Optimized ultrasound-assisted alkaline extraction (UAAE) for high-quality protein extraction from beetroot leaves.

## Key findings

- UAAE produced beetroot leaf proteins with 73.4% protein content and 10% extraction yield.
- BLP obtained via UAAE showed better heat resistance, less aggregation, and higher zeta potential.
- UAAE-extracted beetroot leaf proteins had improved digestibility compared to soy and pea proteins.

## Abstract

•UAAE was optimized with Box-Behnken design for beetroot leaf proteins.•Optimized UAAE yielded 73.4% protein content with 10% extraction yield.•FTIR and microscopy confirmed intact structure and uniform globular proteins.•UAAE improved heat resistance, reduced aggregation, and increased zeta potential.•UAAE enhanced digestibility, supporting vegan food and supplement applications.

UAAE was optimized with Box-Behnken design for beetroot leaf proteins.

Optimized UAAE yielded 73.4% protein content with 10% extraction yield.

FTIR and microscopy confirmed intact structure and uniform globular proteins.

UAAE improved heat resistance, reduced aggregation, and increased zeta potential.

UAAE enhanced digestibility, supporting vegan food and supplement applications.

Beetroot leaf, typically discarded as agricultural waste, is a promising source of plant-based proteins. With growing interest in sustainable and eco-friendly food production, extracting high-quality protein from such by-products supports a circular economy. This study optimized ultrasound-assisted alkaline extraction (UAAE) using a Box-Behnken design to maximize protein yield and content from beetroot leaves. The combination of ultrasound and alkaline treatment has been shown to enhance extraction efficiency and protein techno-functionality in comparison with conventional alkaline method (CAE). Optimal UAAE conditions (40 min, pH 11, 27.2 °C) yielded a protein content of 73.4% with a 10% extraction yield. Fourier transform infrared spectroscopy analysis confirmed that the secondary structure of beetroot leaf protein (BLP) obtained by UAAE remained intact, while microscopic analysis revealed a more compact globular morphology. Additionally, BLP obtained by UAAE showed better heat resistance and less aggregations, supported by a higher absolute zeta potential value (−31.06 mV, compared to −24.03 mV for BLP obtained by CAE). Both BLP obtained by UAAE and CAE displayed proportional increases in foaming capacity and stability with higher protein concentrations. UAAE led to improved digestibility of the BLP compared to legume protein isolates such as soy and pea protein. These findings highlight UAAE as an efficient method to produce high-quality protein from beetroot leaves, suitable for vegan foods, supplements, and pharmaceuticals.