Effect of egg yolk substitution by sweet whey protein concentrate on some Gelato ice cream physical properties during storage

Changes in physical properties of Gelato vanilla ice cream during four weeks of storage using different levels of sweet whey protein concentrate (WPC) substitutions of two levels of egg yolk (4.5% and 9%) were studied. For each level, one control sample with no WPC addition and four levels of WPC substitutions (three replications of each treatment) were made. Determinations of texture, stability and colour were made. Results showed a significant (P < 0.05) difference in hardness (N) among 4.5% and 9% egg yolk samples during four weeks of storage. However, increasing WPC level led to a significant (P < 0.05) decrease in the melting rate between 9% egg yolk samples with increased storage time. On the other hand, there was no significant (P > 0.05) effect on melting rate among 4.5% egg yolk samples with increasing WPC levels. Addition of WPC did not affect whiteness (L) values within 4.5% egg yolk samples, whereas L values were significantly (P < 0.05) affected among 9% egg yolk samples, after one week storage. The results indicated that it is possible to substitute egg yolk with WPC in Gelato, particularly on the 4.5% egg yolk samples, allowing for a cheaper product, without any detrimental change in physical quality parameters.