Improving thermal stability of hydrolysed whey protein-based infant formula emulsions by protein-carbohydrate conjugation

Kamil P Drapala; Mark A E Auty; Daniel M Mulvihill; James A O'Mahony

doi:10.1016/j.foodres.2016.01.028

Improving thermal stability of hydrolysed whey protein-based infant formula emulsions by protein-carbohydrate conjugation

Food Res Int. 2016 Oct;88(Pt A):42-51. doi: 10.1016/j.foodres.2016.01.028. Epub 2016 Feb 1.

Authors

Kamil P Drapala¹, Mark A E Auty², Daniel M Mulvihill³, James A O'Mahony⁴

Affiliations

¹ School of Food and Nutritional Sciences, University College Cork, Cork, Ireland. Electronic address: kamil.drapala@ucc.ie.
² Food Chemistry and Technology Department, Teagasc Food Research Centre, Moorepark, Fermoy, Co. Cork, Ireland. Electronic address: mark.auty@teagasc.ie.
³ School of Food and Nutritional Sciences, University College Cork, Cork, Ireland. Electronic address: d.mulvihill@ucc.ie.
⁴ School of Food and Nutritional Sciences, University College Cork, Cork, Ireland. Electronic address: sa.omahony@ucc.ie.

PMID: 28847402
DOI: 10.1016/j.foodres.2016.01.028

Abstract

Whey protein hydrolysate (WPH) ingredients are commonly used in the manufacture of partially-hydrolysed infant formulae. The heat stability of these emulsion-based formulae is often poor, compared with those made using intact whey protein. The objective of this study was to improve the heat stability of WPH-based emulsions by conjugation of WPH with maltodextrin (MD) through wet heating. Emulsions stabilised by different protein ingredients, whey protein isolate (WPI_E), whey protein hydrolysate (WPH_E), heated WPH (WPH-H_E), and WPH conjugated with MD (WPH-C_E) were prepared and heat treated at 75°C, 95°C or 100°C for 15min. Changes in viscosity, fat globule size distribution (FGSD) and microstructure, evaluated using confocal laser scanning microscopy (CLSM), were used to monitor the effects of hydrolysis, pre-heating and conjugation on the heat stability of the emulsions. Heat stability increased in the order WPH_E<WPI_E<<WPH-H_E<<<WPH-C_E; emulsions WPH_E, WPI_E and WPH-H_E destabilised on heating at 75°C, 95°C or 100°C, respectively. Flocculation and coalescence of oil droplets were mediated by protein aggregation (as evidenced by CLSM) on heat treatment of WPH-H_E emulsion at 100°C, while no changes in FGSD or microstructure were observed in WPH-C_E emulsion on heat treatment at 100°C, demonstrating the excellent thermal stability of emulsions prepared with the conjugated WPH ingredient, due principally to increased steric stabilisation as a result of conjugation.

Keywords: CLSM; Conjugation; Emulsion; Heat stability; Infant formula; Whey protein.