Synthesis and Characterization of Lactose-amines with Respect to Oil-in-Water Emulsion Stability
Fatty amines (hexadecyl-amine) can be esterified to lactose via Schiff-base formation at temperatures of 60Â° C. Extending the time of the reaction results in a darker colored product due to the Maillard reaction. Due to the amphiphilic properties of the lactose-amines, the emulsion stabilization characteristics were investigated. In this study, synthesis of lactose-amines was done at four different heating and cooling cycles from 4 to 24 hours. Lactose-amines processed for 24 hours and 12 hours of constant heating and cooling cycles are named as 24H and 12H, respectively. Lactose-amines 4H and 8H were processed for 4 and 8 hours of constant heating at 60Â°C. The 24H and 12H samples were white in color as they were exposed to heat for short time (due to the cooling cycle) i.e. 2-2.5 and 1.5 hours, respectively, as compare to 4H and 8H (i.e. 4 hours and 8 hours, respectively). It was assumed that white colored compounds are early intermediates of Maillard browning reactions known as Amadori. The light brown color of the 4 hours heat-treated product might contain intermediate products of the Maillard browning reaction. The dark brown colored after 8 hours of constant heating might have advanced Maillard products and polymers. Each lactose-amine sample was used as emulsifiers in oil-in-water (20:80 ratio of oil: water) emulsion at four different concentrations (0.01%, 0.05%, 0.1%, and 1%). Negative controls consisted of hexadecyl-amine and lactose at the same concentrations as stated above, as well as an oil-in-water control. The positive control was an emulsion containing 2% whey protein (WP). Emulsions were formed with a microfluidizer 110S at a pressure of 6,900 psi. Emulsion stability was monitored by measuring the oil droplet sizes of each emulsion on day 0 and destabilization kinetics on day 1 and 5. The oil droplet size distribution and destabilization kinetics of the emulsions prepared with lactose-amines (4H, 8H, 12H, and 24H) at 0.01% of concentration were closer towards the negative controls (lactose, fatty-amine, and o/w). At 1% concentration, emulsions prepared with all types of lactose-amines had smaller droplet size similar to WPC 80. Destabilization kinetic profiles of the emulsions show that 1% lactose-amines produced more stabilized emulsions as compared to WPC 80 with respect to time. Emulsions of 4H and 24H were following the similar trend of droplet size distribution and destabilization rate as of WPC 80. Lactose-amines 8H and 12H emulsions were showing more destabilization and bigger oil droplet size as compared to 4H, 24H, and WPC 80. Droplet size distribution at day 0 and destabilization kinetics from day 0 to day 5 showed that the types of lactose-amines and their increasing concentrations have great influence on the stability of emulsions. This research has shown that lactose-amines produced at treatments of 24 and 4 hours are effective at stabilizing emulsions at 1% concentration.
School:Utah State University
School Location:USA - Utah
Source Type:Master's Thesis
Keywords:agriculture food science
Date of Publication:12/01/2008