Water sorption and diffusion properties of spray-dried dairy powders containing intact and hydrolysed whey protein. (May 2016)

• Record Type: Journal Article
• Authors: Kelly, Grace M.; O'Mahony, James A.; Kelly, Alan L.; O'Callaghan, Donal J.
• Is Part Of: Lebensmittel-Wissenschaft + Technologie =. Volume 68(2016)
• Page Start: 119
• Page End: 126
• Publication Date: 2016-05
• Subjects: Hydrolysed whey protein -- Fick's second law -- Diffusion -- Sorption isotherm -- Microstructure; Food industry and trade -- Periodicals; Food -- Composition -- Periodicals; Microbiology -- Periodicals; Nutrition -- Periodicals; 664.005
• DOI: 10.1016/j.lwt.2015.11.056
• Languages: English
• ISSNs: 0023-6438

Abstract

Abstract: The aim was to compare the effect of intact or hydrolysed whey protein in spray-dried lactose/protein powders on water diffusion properties and microstructure. Dispersions of protein/lactose (0.21:1) containing either intact or hydrolysed whey protein were spray-dried at pilot scale, and physical properties were determined. Lactose/hydrolysed whey protein powders had significantly increased ( P < 0.05) particle density, resulting in lower bulk density and occluded air, and higher interstitial air. Moisture sorption analysis at 25 °C showed that dispersions containing intact whey protein exhibited lactose crystallisation at a lower relative humidity (RH) compared to the dispersions containing hydrolysed whey protein. Hydrolysed whey protein dispersions had a lower monolayer moisture value (mm ) than intact whey protein dispersions, as calculated using the Guggenheim–Anderson–de Boer (GAB) equation. Water diffusivity, determined at 25 °C from water sorption kinetics and the application of a mathematical model based on Fick's 2nd law, was significantly different ( P < 0.05) with respect to the presence of intact or hydrolysed whey protein over the RH range examined (0–60% RH), except at 40% RH. The presence of hydrolysed whey protein resulted in a significantly higher ( P < 0.05) water diffusivity in powders, with potential implications for hygroscopicity, caking, stickiness and flowability in humid environments. Highlights: Higher RH was required to crystallize powders containing hydrolysed whey protein. Higher diffusion of moisture occurred with hydrolysed whey protein. Post-crystallisation structure was more agglomerated with hydrolysed whey protein.