| Abstract: |
This study investigated the feasibility of front-face fluorescence spectroscopy to predict the functional properties of whey. Whey has a commercial interest due to its excellent nutritional value and versatile functional properties, while its attributes depend dramatically on heat treatment, which may alter its suitability for different food applications. Tryptophan front-face fluorescence of the whey and its functional properties, i. e. , foaming, gel-forming, and emulsifying properties, were evaluated after milk heat treatment (at 80 °C with holding times of 0, 5, 10, 15, 20, 25 and, 30 min) in order to detect correlations between tryptophan fluorescence and functional parameters and generate predictive models. Whey samples were obtained by isoelectric precipitation of caseins (pH 4. 6) from reconstituted skim milk powder enriched with whey protein isolate. As expected, heat provoked a decrease on the undenatured whey proteins of milk, the total concentration of proteins in whey and the intensity of tryptophan fluorescence. Gel-forming and emulsifying properties of whey significantly correlated with the maximum intensity of tryptophan (P < 0. 001). Concerning foaming properties, only the foam stability index revealed a weak correlation with tryptophanmaximum intensity parameters(P < 0. 05). Merely the predictive models of emulsifying ability possessed a determination coefficient greater than 0. 8, albeit most models presented a strong significance (P < 0. 001). Thus, although significant correlations were observed, the information provided by tryptophan fluorescence was in general not enough to build strong prediction models. |
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