378: A Sustainable Pathway to Produce Functional Protein From Okara: A Life Cycle Assessment Perspective

Introduction

Okara, an agro-industrial by-product generated during soybean beverage production, holds significant potential due to its high nutritional protein content. Extracting functional protein from okara through enzymatic hydrolysis can enhance its value. Quantifying the environmental impacts of process workflows is essential for selecting sustainable technological pathways. This study evaluates various process stages, including okara production, dehydration, defatting, pretreatment, and protein extraction, to identify environmentally friendly methods.

Methods

A life cycle assessment (LCA) was conducted to quantify environmental impacts throughout five key steps: okara production, dehydration, defatting, pretreatment, and functional protein extraction. The okara production step examined soymilk processing and by-product generation. The dehydration step compared freeze-drying and heating-drying. Hexane use was evaluated for the defatting step. Pretreatment methods included microwave, ultrasonication, and alkali extraction with acid precipitation. The functional protein extraction involved hydrolysis with alcalase and flavorzyme enzymes. A total of 12 experimental sets were conducted to assess yield, protein content, and environmental impacts, facilitating the identification of the most suitable pathway.

Results

The results recommend heating drying for dehydration, eliminating the need for a separate defatting step. Ultrasound pretreatment followed by enzymatic hydrolysis yielded the lowest environmental impacts. Producing 1 kg of pure protein resulted in a Global Warm Potential (GWP) below 200 kg CO₂ eq. The functional protein extraction and the dehydration steps contributed the most to GWP, accounting for 54.2% and 37.6%, respectively, while okara production and post-drying okara treatment contributed 4.9% and 3.3%.

Significance

This study demonstrates the sustainable utilization of okara through LCA-based evaluation of commonly used processing pathways. It offers actionable insights for industries adopting green manufacturing practices by identifying critical environmental impact contributors, particularly dehydration and protein extraction steps.