FT-IR spectroscopy based investigation of stability in wheat germ oil body emulsions as affected by general processing treatments

Abstract

In many plants, unsaturated fatty acids are naturally stored in organelles that are named as oil bodies (OB). Wheat germ is a by-product of wheat flour manufacture that is generated in high tonnage globally. Here, an attempt was made to valorize wheat germ through the generation of natural OB emulsions and their extraction was based on an aqueous method. The natural stability limits for OB emulsions were investigated primarily using FT-IR spectroscopy as influenced by processing treatments such as lyophilization, heating and acidification. Differential scanning calorimetry (DSC) and particle size analysis were carried out to complement the FT-IR data. While freeze-drying seemed to have minimal influence on the structural attributes of OB systems, varying pH and extended heating induced destabilization at varying extents. The mean size values for the unprocessed samples were < 8 µm in the first 15 days of refrigerated storage, which was characterized by significant increases in size (d32 ? 9 µm) after 15 days. For the reconstituted samples, while the mean size values were < 6 µm in the first 21 days of storage, d32 ? 8 µm was observed after 21 days. The location and magnitude of DSC peaks were significantly different between unprocessed vs. lyophilized and reconstituted samples implying processing induced changes in protein structure. At neutral pH, thermal sensitivity of OB emulsions were more pronounced compared to their pH 3 or 9 counterparts. The findings were interpreted primarily in regards to oleosin denaturation and oleosin-oil interactions. Although utilization of hydrocolloids and/or emulsifiers and further homogenization might be necessary to enhance the stability of the current samples, the global capacity in wheat germ generation could justify utilization of wheat germ OB emulsions in food formulations. Graphic abstract: [Figure not available: see fulltext.] © 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.