Writing in its international patent filing, the research team from INIFAP said the dough – made with a blend of Chalqueño, blue VC-42 or 'Bolita' and red Cónico – resulted in a “nutraceutical mass with natural colors” that could be used to make traditional blue tortillas or maize-based fried snacks.
Driving up antioxidants
Use of the dough in these two specific food groups, particularly tortillas, could be significant.
Per capita consumption of maize in Mexico was around 107kg per year, they said, about 90% of which was consumed in tortillas; but most tortillas were typically made with white maize rather than antioxidant-rich blue or purple varieties.
“The tortilla of the invention is characterised in that it contains twice as many antioxidants as the traditional tortilla, without its sensory or nutritional qualities being effected,” said the INIFAP researchers.
“The nutraceutical blue tortilla provides an option for substantially increasing the ingestion of antioxidants among the Mexican population using a popular consumer product.”
Anthocyanins – increase and protect
The researchers said the key to the dough's antioxidant punch was its anthocyanin content – a pigment found in the aleurone layer of the maize, just below the hull or pericarp of corn grain.
The three maize varieties used in the dough, they said, had been selected or developed for these higher levels of the pigment, which ensured higher levels of vitamin C and soluble vitamin E Trolox.
Mexican maizes showed “great variation” in anthocyanin content, they said, much of which depended on growing environment. Breeds adapted to higher altitudes, for example, contained much higher levels of anthocyanins than those adapted to the subtropics.
This “great diversity in agronomic characteristics, adaptation and physical and chemical characteristics” had been used to adapt “much more stable” varietals, they said. Blue VC-42 corn, for example, from the 'Bolita' race had been developed and released in 2011 by INIFAP.
Importantly, the corn grains used in the dough had also been processed in such a way that protected and maintained antioxidant levels, the researchers said.
Traditional methods like nixtamialization, where the grain is soaked in an alkaline solution, washed and then hulled or ground, were “very aggressive” and destroyed up to 70% of anthocyanin content in the raw grain, they said. But using extrusion or fractionated nixtamalization instead was gentler on the grain and therefore reduced the loss of anthocyanins..
Perfecting the blend
The researchers said they had tested a range of ratios to perfect the dough and found blending Chalqueño with VC-42 at a wet ratio of 70:30 ensured a strong enough texture for the manufacture of tortillas.
Incorporating the VC-42 was important because alone, the blue/purple grain of Chalqueño was floury and not strong enough to withstand processing.
“This mixture yielded a similar dough texture to that of a white grain corn intended for this purpose,” the researchers wrote.
The pericarp/aleurone layer of red Cónico – rich in insoluble fiber and antioxidants – was then incorporated as a functional ingredient during the treatment of the grain blend, ideally at around 3% by wet weight (wW), during the grinding step.
Regarding antioxidants, the researchers said this treatment was “outstanding, introducing 50% more antioxidants than white corn tortillas and traditional blue/purple tortillas”.
Importantly, shelf-life was not impacted – the tortilla could be stored for ten days refrigerated – and the mineral composition was similar to regular white tortillas.
Source: WIPO Publication No. WO2017105210
Published: June 22, 2017. Filed: December 7, 2016.
Title: “Nutraceutical dough obtained from a mixture of native maize varieties (Chalqueño, Blue VC-42 (Bolita), Red Conico), uses thereof and production method of same”
Authors: National Institute for Forest, Agriculture and Livestock Research (INIFAP)