Foam stability of cloudy carrot juice: effects of protein sources and foaming conditions

Résumé

Carrot is an important crop by containing bioactive compounds such as carotenoids, vitamins and dietary fiber. But the shelf life of fresh carrot is limited due to its moisture content. The aim of this study was to evaluate the effects of using different amounts of egg albumen (EA) and whey protein isolate (WPI) and their interactions on carrot juice foam stability. For this purpose, the experimental design was built by response surface method and employing EA amount (5-10-15%), WPI amount (0-5-10%) and whipping time (4-6-8 min) as independent variables, while selecting the density and overrun as foam stability evaluation criteria. Among the tested levels of independent variables, the lowest density (0.2433 g/ml) and the highest overrun value (2.3466) was observed for 15% EA with 10% of WPI incorporation and the 8 min whipped foam. The levels of EA and/or WPI were found significantly effective on the selected responses (p<0.05), however only the interaction of whipping time with WPI amount had significant effect on density and overrun values. The foam stability improvement with WPI incorporation was confirmed by air bubble diameter distribution analysis, and the lowest average foam diameter with more homogeneous diameter distribution was obtained for 15% EA+10% WPI foam.