NaCl induces flocculation and lipid oxidation of soybean oil body emulsions recovered by neutral aqueous extraction

Abstract

BACKGROUND: Soybean oil bodies (SOB) are naturally pre-emulsified lipid droplets recovered directly from soybean seeds. Almost all food emulsions contain salts. However, it was not clear how the incorporation of salts affected the physicochemical stability of SOB.RESULTS: This study investigated the effect of NaCl (0-1.2%) on the physical and oxidative stability of SOB emulsions under neutral (pH 7) and acidic (pH 3) conditions. In the presence of NaCl, the SOB emulsion (pH 7) showed strong flocculation during storage due to electrostatic screening. The NaCl-induced flocculation of SOB was attenuated at pH 3, which may be due to the difference in conformation or interaction of the protein interfaces covering SOB at different pH values. The increase in ionic strength or acid conditioning treatment resulted in a remarkable increase in the stability of SOB emulsions against coalescence. The confocal laser scanning microscopy images also confirmed the NaCl-induced changes in the flocculation/coalescence properties of SOB. The oxidative behavior tests indicated that SOB emulsions containing NaCl were more susceptible to lipid oxidation but protein oxidation was inhibited due to electrostatic screening, which reduced pro-oxidant accessibility of unadsorbed proteins in the emulsion. This oxidative behavior was attenuated at pH 3. CONCLUSION: The incorporation of NaCl significantly reduced the physical and oxidative stability of the SOB emulsion, and acidic pH mitigated NaCl-induced flocculation and lipid oxidation of SOB.

Soybean Oil Bodies as a Milk Fat Substitute Improves Quality, Antioxidant and Digestive Properties of Yogurt

“…The microstructure was determined according to the methods of Zhou et al with some modification [ 22 ]. Laser scanning confocal microscopy (Deltavision OMX SR, GE, Fairfield, CT, USA) was used for observation.…”

Physical and oxidative stability of astaxanthin microcapsules prepared with liposomes

“…The changes of particle size, ζpotential, astaxanthin retention rate, peroxide value (PV), and acid value (AV) of microcapsule powders in different condition (light and dark), different aerobic environments (oxygen and vacuum), different storage temperatures (4, 25, 60 °C), and different pH levels (3,7,10) were analyzed within 14 days.…”

“…Its surface proteins are mainly divided into three types: Oleosin (15–26 ku), caleosin (25–35 ku) and steroprotein (40–55 ku) 1 . Oleosin is highly hydrophobic and forms strong elastic networks at the air‐water and oil–water interfaces in the absence of phospholipids 2‐3 . Caleosin could be more directly involved in membrane and OB reactions 4 .…”

“…1 Oleosin is highly hydrophobic and forms strong elastic networks at the air-water and oil-water interfaces in the absence of phospholipids. [2][3] Caleosin could be more directly involved in membrane and OB reactions. 4 Steroleosin is similar in structure to caleosin but it does not stabilize the OBs' structure.…”

Oil bodies extracted from high-oil soybeans (Glycine max) exhibited higher oxidative and physical stability than oil bodies from high-protein soybeans

“…6 The size and composition of OBs may vary depending on the plant from which they are derived; the particle size of water-extracted OBs typically range from 0.4 µm to 2.0 μm. 7,8 Soybean OBs have higher thermal stability and resistance to coalescence compared to sesame and hazelnut OBs. 9 However, when isolating soybean oil bodies (SOBs) by aqueous extraction, co-extracted exogenous proteins often bind to the OB surface, which can severely damage the physical stability and oxidative stability of the OBs as a result of enzymatic degradation.…”