Published in Food Chemistry, European researchers investigated the antioxidant activity of four red- and purple-flesh potato flours and extruded snacks made from these flours.
One red-fleshed variety Herbie 26 was tested, along with three purple-fleshed potatoes: Valfi, Blue Congo and Salad Blue.
“There was a significant influence of potato variety on the experimental flour and snack properties,” the researchers wrote.
Findings showed snacks produced with colored potato flour contained, on average, 40% more polyphenols and an antioxidant activity 2-3 times higher than regular potato-based snacks.
“Dough destined for pellet extrusion and subsequently snack frying, enriched with colored-potato flour, had higher contents of total polyphenols than dough containing only industry made potato grits,” the researchers said.
However, low shear extrusion and frying “significantly contributed to changes” in the antioxidant activity of the end snacks, the researchers added.
For example, antioxidant activity decreased in Blue Congo- and Valfi-snacks but increased 50% in Salad Blue- and Herbie 26-snacks.
“These differences could be due to a higher degradation of total polyphenols in snacks supplemented with Blue Congo and Valfi potato flour,” they suggested.
However, while loss of polyphenols varied, losses remained lower than when regular potato flours were processing into snacks.
“These results suggest that the polyphenols present in tubers of colored-flesh varieties are better stabilized during thermal processes than polyphenolic compounds in potatoes of traditional colored flesh,” the researchers wrote.
In addition to improved antioxidant activity, the researchers said use of colored potatoes added “novel visual characteristics”.
“The utilization of experimental, colored potato flours favorably affected the color and expansion index of the obtained snacks and did not change their texture”, they said.
Processing created color loss in some potato varieties but improvement in others.
The anthocyanin content – water-soluble color pigment – remained highest throughout processing for purple-fleshed Blue Congo and red-fleshed Herbie 26 potatoes.
Out of all four varieties tested, red-colored Herbie 26 potatoes resulted in an attractive pink snack color, the researchers said.
Source: Food Chemistry
Published online ahead of print, doi: 10.1016/j.foodchem.2014.09.033
“Anthocyanin and antioxidant activity of snacks with coloured potato”
Authors: A. Nemś, A. Pęksa, AZ. Kucharska, A. Sokół-Łętowska, A.Kita, W. Drożdż, and K. Hamouz