Insights of the ability of gelatinized fractions from non-chemical modified corn, rice, wheat, and waxy corn starches to stabilize O/W emulsions

Non-chemical modified native corn (NCS), rice (NRS), wheat (NWS), and waxy corn (WCS) starch dispersions (5.0 g/100 g water) were heated (90 degrees C, 20 min) for producing gelatinized starch dispersions (GSD). GSD were centrifuged and the supernatant starch fraction (SF) was used for preparation of O/W emulsions (dispersed phase mass fraction of 0.15). The interfacial activity of the different SFs was assessed by dynamic interfacial tension measurements. The SF from NCS, NRS and NWS showed significantly higher and faster interfacial tension decaying rates than the WCS SF. All the SFs were able to form O/W emulsions. The volume-weighted mean droplet diameter (d(4,3)) of the fresh emulsions were significantly different ranging from similar to 1.4 to 19 pm. The emulsions made with SFs from NCS, NRS and NWS showed larger d(4,3) and faster creaming rates than that made with SF of WCS. The latter produced an emulsion with practically unchanged d(4,3) and slowest creaming rate with storage time. FTIR, XRD, zeta-potential measurements, and adsorption time relaxation constants allowed postulating that emulsion stability was related to the formation of inclusion starch-lipid complexes at the oil-water interface. This study provides insights about the phenomena occurring on O/W emulsions interface due to interactions between cooked starch fractions from different botanical origin and lipids, and which might occur during food processing.