Developing Spectrophotometric & Colorimetric Field Tests to Measure Beta-Carotene Concentration of Biofortified Cassava

Overview

Objectives/Goals In an effort to fight vitamin A deficiency, a leading cause of morbidity and mortality in Africa, South America, and Southeast Asia, HarvestPlus and BioCassavaPlus have biofortified cassava to increase its beta-carotene concentration. Because carotenoid concentration is affected by climate and growing conditions, field tests are needed to maintain the integrity of these biofortification programs. Current HPLC methods are timely and expensive, making spectrophotometric and colorimetric assays more desirable for field tests. Methods/Materials Samples were prepared in two ways: beta-carotene was extracted and then reconstituted to 1:2 dilutions to be measured on the spectrophotometer and colorimeter; and dry samples were homogenized and measured on the colorimeter. Linear regressions were plotted to depict the correlation between the known concentrations and the values obtained using the spectrophotometer and colorimeter. Results Spectrophotometric assays were reasonably effective, with R^2 = 0.7284. For wet colorimetric assays, there was a strong correlation between the a*, b*, C*, and h values and the concentration of beta-carotene, with R^2=0.82, R^2=0.89. R^2=0.90, R^2=0.74,respectively. Both wet assays were more effective than dry colorimetric tests. It is important to note that for actual field tests, standard curves must first be created for each individual spectrophotometer and colorimeter. Conclusions/Discussion Excitingly, both spectrophotometric and colorimetric assays have much potential to be used as field tests, saving nonprofit organizations like HarvestPlus and BioCassavaPlus time and money, resources they can use to further their impact preventing vitamin A deficiency and saving lives doing so. This study also suggests that carotenoid concentration determines the color values of extracted samples. More broadly this suggests that higher concentrations of beta-carotene results in a color shift to a more vivid yellow-green, away from being a white-yellow color. More research should be done to evaluate the limitations of spectrophotometric and colorimetric assays as field tests and their potential applications to other biofortified foods.

Competition history

• CSEF 2014 Chemistry · Entry S0622

Resources

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