Physical properties and carotenoid content of maize kernels and its nixtamalized snacks

Vitamin A and protein deficiencies afflict hundreds of millions of people, and because maize is a staple food providing a large portion of energy and nutrients for many, its genetic fortification or biofortification could significantly contribute to alleviating malnutrition. Therefore, we measured carotenoid and tryptophan contents for grain, nixtamalized (lime-cooked) maize, and processed snacks of 13 maize genotypes including landraces, quality protein maize (QPM) and non-QPM hybrids. An average 36% loss of provitamin A and an 8% increase in tryptophan were observed following nixtamalization and subsequent snack preparation by deep-frying. The correlations for physical properties of grain and maize flour with provitamin A were calculated to investigate whether secondary traits may be useful as indicators of provitamin A content. The correlation of chroma values with provitamin A contents was significant (P < 0.05) for 15% and 25% hydrated maize flour (r = 0.57 and r = 0.51, respectively), but was not significant for whole maize kernels.Industrial relevanceYellow maize is used as food and feed. Possible methodologies for rapid carotenoid estimation for industrial purposes like corn flakes or for the poultry industry will be of importance. One of the objectives of this work was to establish correlation between physical parameters and carotenoid concentration in maize. The correlation of chroma values with provitamin A contents was significant (P < 0.05) for 15% and 25% hydrated maize flour (r = 0.57 and r = 0.51, respectively), which could be explored as a methodology for rapid and inexpensive estimation of provitamin A and total carotenoids in maize. Lime-cooking is the traditional method for maize preparation in Mexico and Central America. The estimation of carotenoid losses during this process and the bioavailability studies are important to measure the impact of biofortified maize in the populations with provitamin A deficiencies. During this work we have determined that an average 36% loss of provitamin A and an 8% increase in tryptophan were observed following nixtamalization and subsequent snack preparation by deep-frying.