Bioactivity of Antioxidants in Extruded Products Prepared from Purple Potato and Dry Pea Flours

• Published in: Journal of agricultural and food chemistry 2011-08, Vol.59 (15), p.8233-8243
• Main Authors: Nayak, Balunkeswar, Liu, Rui Hai, Berrios, Jose De J, Tang, Juming, Derito, Christopher
• Format: Article
• Language: English
• Subjects: Antioxidants - analysis; Biological and medical sciences; Chemical Changes Induced by Processing/Storage; Flour - analysis; Food Handling; Food industries; Fruit and vegetable industries; Fundamental and applied biological sciences. Psychology; Hep G2 Cells; Humans; Pisum sativum - chemistry; Plant Extracts - analysis; Solanum tuberosum - chemistry
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf200732p

Measuring antioxidant activity using a biologically relevant assay adds important evidence to aid in understanding the role of phytochemicals based on data from in vivo and chemical assays of extrusion processed purple potato and pea flours. A cellular antioxidant activity assay could provide biologically relevant information on bioactive compounds in raw as well as processed food products. The objective of this study was to investigate the complete phytochemical profiles, antioxidant activity, cellular antioxidant activity, and their contribution to bioactivity in purple potato flour, dry pea flour, raw formulations, and extrusion cooked products prepared with the above ingredients. The free fraction of extracts contributed 68, 64, and 88% to total phenolics, total antioxidant activity (ORAC value), and total flavonoids, respectively, in purple potato flour (PPF). Similarly, extracts in the free fraction contributed 87, 86, and 64% to total phenolics, total antioxidant activity (ORAC value), and total flavonoids, respectively, in dry pea flour (DPF). The amount of total phenolics and total flavonoids in purple potato flour and the antioxidant activity of PPF and DPF were comparable to published data. However, a higher amount in the total flavonoids and lower in the total phenolics of DPF were observed. Caffeic, p-coumaric, and ferulic acids were mostly observed in the bound extracts of raw formulations as in the extrudates, whereas chlorogenic acid was predominant in the free extracts. The extruded products had significantly higher (p < 0.05) content of total phenolics, ORAC antioxidant activity, and flavonoids, compared to the raw formulations. Extrusion processing increased the cellular antioxidant activity of the extrudates prepared from 35:65 and 50:50 PPF/DPF (w/w) of ingredients compared with control raw formulations in a dose-dependent manner. Increase of PPF significantly increased (p < 0.05) the cellular antioxidant activity of 35–50% PPF formulations.