094: The Impact of Supercritical Carbon Dioxide Processing on the Aroma and Physicochemical Properties of Soybean Flour

Introduction

Soybeans are rich in protein (35-40%) but have limited food applications due to undesirable volatile compounds that affect flavor and consumer acceptance of soybean flour. This study aimed to improve the aroma profile using a single-step SC-CO2 extraction process to remove lipids and undesired volatile compounds without using petroleum-based toxic solvents.

Methods

The extractions of lipids and removal of volatile compounds from soybean flours were carried out using hexane (H1:23℃ and H2:60℃), as well as SC-CO2 treatments (S1:40 MPa/60℃/4 hours with a 2 L/min constant CO2 flow rate and S2: S1 + an additional 2 hours of extraction at 15 MPa and 60℃ with 2 L/min CO2 flow rate). Then, the effects of these extraction conditions on soybean flour properties were assessed, including particle size distribution, composition, volatile compound analysis, color, functional properties, rheological behavior, morphology, and textural qualities. Statistical analysis was performed using Tukey’s test at a 5% significance level.

Results

The lipid extraction yields (~20%) were comparable between SC-CO2 and conventional hexane extractions. However, SC-CO2 extraction significantly reduced the volatile compound concentration in soybean flour (0.63–1.00 µg/g) compared to hexane extraction (1.44–1.68 µg/g), while untreated soybean flour had a much higher concentration (~7 µg/g). SC-CO2-treated flour exhibited superior characteristics, including smaller particle sizes (<250 µm, ~70%), improved protein purity during protein extraction, and a brighter color than hexane-extracted flour. Compared to untreated soybean flour, SEM images revealed a more disrupted and rough structure in defatted flour. S2 significantly enhanced functional properties, increasing WAI to 3.14 g/g, FC to 95%, and FS to 55%, outperforming hexane-extracted flour. Textural analysis showed SC-CO2-treated flour had greater cohesiveness and gumminess, reflecting improved structural integrity and resistance to crumbling.

Significance

The expected outcomes of this research are to (i) achieve the simultaneous extraction of lipids and undesirable off-aromas in a single, streamlined step, (ii) the potential of a greener method for improving the sensory properties and functional characteristics of soybean flour, and (iii) eliminate the use of petroleum-based toxic solvents.

Authors: Sumanjot Kaur, Ali Ubeyitogullari