Antioxidant Properties of High-Lutein Grain-Based Functional Foods

in comparison with Ferulic Acid and Lutein

Agriculture and Agri-Food Canada, Guelph Food Research Centre, 93 Stone Road West, Guelph, ON, Canada

^*Corresponding author:

El-Sayed M. Abdel-Aal

Agriculture and Agri-Food Canada

Guelph Food Research Centre

93 Stone Road West, Guelph

ON, Canada, N1G 5C9

Tel: 226-217-8079

Fax: 226-217-8181

e-mail: abdelaale@agr.gc.ca

Abstract

Dietary antioxidants could alleviate oxidative damage to cellular components via their ability to scavenge reactive oxygen species and other free radicals. In this regard wholegrain foods are recognized sources of dietary antioxidants and thus they are linked with health promotion and reduced risk of chronic diseases. In the current study high-lutein wholegrain bread, cookie and muffin products were assessed in terms of antioxidant properties based on their ability to scavenge peroxyl, ABTS and DPPH radicals and compared with ferulic acid and lutein, the primary antioxidants in the products. Aqueous methanol extract and bound diethyl ether/ethyl acetate extract followed alkaline hydrolysis were employed in the antioxidant measurement. Antioxidant capacity of the products was influenced by food product, type of extract (e.g. unbound versus bound) and antioxidant assay. In the ORAC test similar antioxidant capacities were obtained for unbound phenol extracts either from fortified or unfortified products, while significant differences were observed in bound phenol extracts. Significant differences were also found between unbound and bound phenol extracts in their ability to scavenge ABTS radical cation. In the DPPH assay lutein-fortified products had scavenging capacities significantly higher than that of the unfortified ones. In general, the bound phenolic extracts contribute significantly higher to the antioxidant capacity than the unbound phenol extracts. Only the DPPH test showed the contribution of lutein to the antioxidant capacity. At a lutein level of about 1.1-1.2 mg per serving (e.g. 30g) the products would boost the daily intake of lutein and antioxidants, as well as consumption of wholegrain foods.

Keywords: Antioxidant capacity, ORAC, TEAC and DPPH assays, Lutein, Ferulic acid, high-lutein wholegrain foods.

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