Effect of hydrolyzed whey protein on surface morphology, water sorption, and glass transition temperature of a model infant formula.
Physical properties of spray-dried dairy powders depend on their composition and physical characteristics. This study investigated the effect of hydrolyzed whey protein on the microstructure and physical stability of dried model infant formula. Model infant formulas were produced containing either intact (DH 0) or hydrolyzed (DH 12) whey protein, where DH=degree of hydrolysis (%). Before spray drying, apparent viscosities of liquid feeds (at 55°C) at a shear rate of 500 s(-1) were 3.02 and 3.85 mPa·s for intact and hydrolyzed infant formulas, respectively. On reconstitution, powders with hydrolyzed whey protein had a significantly higher fat globule size and lower emulsion stability than intact whey protein powder. Lactose crystallization in powders occurred at higher relative humidity for hydrolyzed formula. The Guggenheim-Anderson-de Boer equation, fitted to sorption isotherms, showed increased monolayer moisture when intact protein was present. As expected, glass transition decreased significantly with increasing water content. Partial hydrolysis of whey protein in model infant formula resulted in altered powder particle surface morphology, lactose crystallization properties, and storage stability.
Teagasc Food Research Centre, Moorepark, Fermoy, Co. Cork, P61 C996, Ireland; School of Food and Nutritional Sciences, University College Cork, Cork, T12 Y337, Ireland.
Grace M
GM
Kelly
School of Food and Nutritional Sciences, University College Cork, Cork, T12 Y337, Ireland.
James A
JA
O'Mahony
School of Food and Nutritional Sciences, University College Cork, Cork, T12 Y337, Ireland.
Alan L
AL
Kelly
Teagasc Food Research Centre, Moorepark, Fermoy, Co. Cork, P61 C996, Ireland. Electronic address: donal.ocallaghan@teagasc.ie.
Donal J
DJ
O'Callaghan
D002152:Calorimetry, Differential Scanning; D055598:Chemical Phenomena; D003460:Crystallization; D003890:Desiccation; D004655:Emulsions; D005504:Food Analysis; D005511:Food Handling; D006017:Glycolipids / Q000737:chemistry; D006023:Glycoproteins / Q000737:chemistry; D006868:Hydrolysis; D041943:Infant Formula / Q000737:chemistry*; D007785:Lactose / Q000737:chemistry; D066292:Lipid Droplets; D008855:Microscopy, Electron, Scanning; D011208:Powders / Q000737:chemistry; D014783:Viscosity; D014867:Water / Q000032:analysis; D000067816:Whey Proteins / Q000737:chemistry*
D004655:Emulsions; D006017:Glycolipids; D006023:Glycoproteins; D011208:Powders; D000067816:Whey Proteins; C110367:milk fat globule; D014867:Water; D007785:Lactose
hydrolyzed whey; infant formula; sorption isotherms; storage stability; surface morphology