Comparing the stability of beverage emulsions prepared at acidic and neutral pH using mildly fractionated faba bean (Vicia faba) soluble fractions.

Tuesday, April 30, 2024

5:00 PM – 6:00 PM EDT

Presenting Author(s)

Madhurima Bandyopadhyay, M.Sc (she/her/hers)

PhD Candidate
University of Saskatchewan
Saskatoon, SK, Canada

Co-Author(s)

Supratim Ghosh, PhD (he/him/his)

Associate Professor
University of Saskatchewan
Saskatoon, SK, Canada
MN

Michael Nickerson (he/him/his)

Head of the Department
University of Saskatchewan
Saskatoon, Saskatchewan, Canada

Abstract: An aqueous mild-fractionation using one-step centrifugation was conducted on faba bean flour dispersion (at the native pH of 6.7) to obtain albumin protein-rich soluble fractions. The duration of centrifugation was varied keeping the speed constant. The soluble fractions were directly utilized to make the oil-in-water emulsions at pH 7 and pH 2. The long-term stability of the emulsions was determined against different concentrations of NaCl (salt) and heat treatment at 90°C for 30 min. The average droplet size of all the emulsions prepared at pH 7 remained unchanged (0.4 µm) even at 1 M salt, while at acidic pH, it increased from 0.4 µm to >1.0 µm at 0.5 and 1 M salt. On heating, the pH 7 emulsions did not show any aggregation; even with the presence of salt, droplet size remained unchanged. In contrast, heated acidic emulsions showed an increase in average droplet size ( >3.0 µm) at 1 M salt. Visual observations revealed phase separation for the heated and 1 M salt-added acidic emulsions, while slight creaming was observed for those at pH 7. Creaming velocity under accelerated gravitation (2100g) increased with salt at pH 7 (680 to 1081 µm/min), which was lower than those at pH 2 (900 to 3000 µm/min). Heating improved the creaming velocity at pH 7, unlike those at pH 2. At pH 7, soluble fractions obtained via longer centrifugation led to improved emulsion stability against heating, however, no such difference was observed at pH 2. Overall, the emulsions at pH 2 were less stable against salt and heating compared to the emulsions at pH 7, supposedly due to the difference in the colloidal interactions acting between the mildly fractionated proteins at the droplet interfaces at different pH values. Beverage emulsions stabilized by albumin-rich mildly fractionated proteins can be sustainable and cost-effective method.