Optimizing Wolffia globosa protein extraction by ultrasonic pretreatment and enhancing protein attributes through LAB fermentation

Abstract

The rising global population is generating food security issues, particularly in protein demands and nutritional quality. Many plant-based foods have been explored to meet this demand, although they often lack total protein or protein quality. Therefore, underutilized water crops, such as Wolffia globosa, offer great potential for alternative protein production. This study investigated the parameters of ultrasonic-assisted alkaline extraction and probiotic fermentation to extract and enhance the qualities of Wolffia protein. Response surface methodology was utilized to optimize ultrasound-assisted alkaline extraction, resulting in a maximum soluble protein yield of 118.44 ± 13.60 mg g⁻¹ under conditions of 95% amplitude, 16 minutes extraction time, and a 1 : 20 g mL⁻¹ solid-to-liquid ratio. This method increased total protein content by 127%. Subsequent fermentation with Lactobacillus plantarum 2075 then improved nutritional quality by raising digestibility from 55.82% to 70.45%, increasing essential amino acid content, and raising antioxidant activity by 15.24% and phenolic content by 98.89% relative to the raw sample. Fermentation also modified technofunctional properties of the extracted sample, reducing foaming capacity and emulsion activity but improving the foam and emulsion stability. These findings highlight that ultrasonic-assisted alkaline extraction improves protein yield, and sequential fermentation further modifies protein characteristics and significantly enhances nutritional quality. The dual processing strategy for Wolffia globosa thus presents a promising sustainable alternative for quality plant protein in diverse food applications.