Influence of temperature and humidity on the stability of carotenoids in biofortified maize genotypes

Abstract

Maize is a staple crop that has been the subject of biofortification efforts to increase the natural content of provitamin A carotenoids. While significant progress towards increasing provitamin A carotenoid content in maize varieties has been made, post‐harvest handling factors that influence carotenoids stability during storage has not been fully established. The objectives of this study were to determine carotenoid profiles of six selected provitamin A biofortified maize genotypes at various developmental stages, and assess the stability of carotenoids in maize kernels during controlled storage conditions (12 month‐period) including elevated temperature and relative humidity (RH). There were no significant changes in the content of individual carotenoids within genotypes during kernel development from 45 days after pollination through the time of harvest. Carotenoid losses through traditional grain drying were also minimal (<9%). However, stability of carotenoids in maize kernels over storage time after harvest was found to be dependent on both temperature and humidity, with variation observed among genotypes. Different forms of provitamin A carotenoids follow similar degradation rate. Carotenoid degradation rate appears to be independent of initial carotenoid concentration. Genotype (C17/DE3) had a degradation rate 2× faster than the other genotypes evaluated (P<0.001). These differences in carotenoid stability to controlled storage were attributed, in part, to observed differences in physical properties of the kernels (surface area and porosity). These results support the notion that effective control of moisture content and temperature of the kernels during storage conditions is essential to reduce the speed of degradative reactions.Support or Funding InformationFunding provided by NSF, Harvest Plus, Colciencias and Fulbright‐Colombia.