ARS | Publication request: Effect of extrusion on the antioxidant capacity and color attributes of expanded extrudates prepared from purple potato and yellow pea flour mixes

Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 24, 2011
Publication Date: August 5, 2011
Citation: Nayak, B., Berrios, J.D., Power, J.R., Tang, J. 2011. Effect of extrusion on the antioxidant capacity and color attributes of expanded extrudates prepared from purple potato and yellow pea flour mixes. Journal of Food Science. 76(6):C874-C883. DOI: 10.1111/j.1750-3841.2011.02279x.

Interpretive Summary: The effect of extrusion cooking on the antioxidant capacity and color attributes of extruded products prepared from three selected formulations of purple potato and yellow pea flours using a co-rotating twin screw extruder were studied. The expansion of the extruded products varied from 3.93 to 4.75, which is considered appropriate for expanded snack type products. Color attributes such as brightness and whiteness, yellowness and/or darkness were evaluated to determine the changes that color rich anthocyanin compounds underwent as a consequence of extrusion cooking. The total antioxidant capacities of the extruded products were high and not different from their respective raw formulations, which indicated that the extrusion cooking processing preserved the original antioxidant capacities present in the raw materials. The total phenolic contents of the extruded products varied from 2088 to 3766 u.g of gallic acid equivalent/g dry weight sample and retained 73 - 83 % of total phenolic from the raw formulations after extrusion. This study demonstrated the potential for the production of puffed extruded food products with the improved antioxidant content from colored potatoes and pulse-based formulations.

Technical Abstract: The effect of extrusion cooking on the antioxidant capacity and color attributes of extruded products prepared from three selected formulations of purple potato and yellow pea flours using a co-rotating twin screw extruder were studied. Expansion ratios of the extruded products varied from 3.93 to 4.75. The total antioxidant capacities (TAC) of the extruded products, using DPPH assay, were 3769 - 4116 |ig trolox equivalent/g dry weight sample and not significantly different (p < 0.05) from their respective raw formulations. The total phenolic contents (TP) of the extruded products varied from 2088 to 3766 |ig of gallic acid equivalent/g dry weight sample and retained 73 - 83 % of TP from the raw formulations after extrusion. Color attributes such as brightness, chroma and hue angles reflected the degradation of anthocyanins in the extruded products. However, extrusion cooking retained antioxidant capacities of the raw formulations in the extruded products either in their natural forms or degraded products with radical scavenging activity. This study demonstrated the potential for the production of puffed extruded food products with the improved antioxidant content from colored potatoes and pulse-based formulations.