Antioxidant properties of whey protein hydrolysates as measured by three methods
- 912 Downloads
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.
KeywordsWhey Hydrolysates ABTS Liposomes Chemiluminescence
This work was supported by the Ministry of Education, Youth and Sports of the Czech Republic (research project MSM 6046137305) and by the Socrates—Erasmus program.
- 14.Peña-Ramos EA, Xiong YL (2001) Antioxidative activity of whey protein hydrolysates in a liposomal system. J Dairy Sci 84:2577–2583Google Scholar
- 16.Lowry OH, Rosebrough NJ, Farr AL, Randall RJ (1951) Protein measurement with folin phenol reagent. J Biol Chem 193:265–275Google Scholar
- 18.Adler-Nissen J (1986) Some fundamental aspects of food protein hydrolysis. In: Enzymic hydrolysis of food proteins. Elsevier, New York, pp 9–19Google Scholar
- 23.Ursini F, Maiorino M, Valente M, Ferri L, Gregolin C (1982) Purification from pig liver of a protein which protects liposomes and biomembranes from peroxidative degradation and exhibits glutathione peroxidase activity on phosphatidylcholine hydroperoxides. Biochim Biophys Acta 710:197–211Google Scholar