Kelly Grace M, O'Mahony James A, Kelly Alan L, O'Callaghan Donal J
Teagasc Food Research Centre, Moorepark, Fermoy, Co. Cork, P61 C996, Ireland; School of Food and Nutritional Sciences, University College Cork, Cork, T12 Y337, Ireland.
School of Food and Nutritional Sciences, University College Cork, Cork, T12 Y337, Ireland.
J Dairy Sci. 2016 Sep;99(9):6961-6972. doi: 10.3168/jds.2015-10447. Epub 2016 Jun 16.
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.
喷雾干燥乳粉的物理性质取决于其成分和物理特性。本研究调查了水解乳清蛋白对干燥型婴儿配方奶粉微观结构和物理稳定性的影响。制备了含有完整（DH 0）或水解（DH 12）乳清蛋白的婴儿配方奶粉模型，其中DH =水解度（%）。在喷雾干燥前，完整婴儿配方奶粉和水解婴儿配方奶粉在55°C、剪切速率为500 s(-1)时液体进料的表观粘度分别为3.02和3.85 mPa·s。复水后，与完整乳清蛋白粉相比，含有水解乳清蛋白的粉末具有显著更高的脂肪球尺寸和更低的乳液稳定性。水解配方奶粉的粉末中乳糖结晶发生在相对湿度较高时。拟合吸附等温线的 Guggenheim-Anderson-de Boer 方程表明，当存在完整蛋白质时，单层水分增加。正如预期的那样，玻璃化转变随着含水量的增加而显著降低。婴儿配方奶粉模型中乳清蛋白的部分水解导致粉末颗粒表面形态、乳糖结晶特性和储存稳定性发生改变。
