Antioxidant properties of whey protein hydrolysates as measured by three methods |
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Authors: | Adriena Dryáková Anne Pihlanto Pertti Marnila Ladislav Čurda Hannu J T Korhonen |
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Affiliation: | 1. Institute of Chemical Technology, Technická 5, 166 28, Prague 6, Czech Republic 2. MTT Agrifood Research, 31600, Jokioinen, Finland
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Abstract: | Four microbial proteases (Alcalase, Flavourzyme, Neutrase and Protamex) were used for the preparation of whey protein hydrolysates.
The aim of this research was to find out whether these hydrolysates can be used as a source of whey derived antioxidants.
Hydrolyzed samples, including their unhydrolyzed protein solutions were tested by the ABTS (2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic
acid) decolorization assay, by the total radical-trapping potential method and by the assay of liposomes peroxidation (fluorescence
photometry). Antioxidant properties were enhanced by hydrolysis in most of cases. Alcalase hydrolysates were found as the
most effective antioxidants as determined by ABTS assay (~50% of antioxidant activity at 0.1 mg ml−1 of hydrolysate in reaction) and fluorescence photometry. Liposomes were oxidized ~50% less (1.1 μM of α-tocopherol equivalent)
with Alcalase hydrolysates additive (at 5.85 mg ml−1 of hydrolysate in reaction). Hydrolysates did not inhibit the oxidation of liposomes at concentrations below 1.0 mg ml−1 in reaction. On the contrary, results of total trapping potential method did not agree with findings observed in other tests.
In this assay, Neutrase hydrolysates showed the best antioxidant properties. Pro-oxidant properties were observed in solutions
containing (prior to the enzyme Protamex addition only) intact whey protein as determined by the measurement of the liposome
peroxidation. The ABTS assay was optimized for the evaluation of the antioxidant activity in whey protein hydrolysates. The
reaction time should be prolonged to avoid underestimation of the antioxidant activity. |
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