Effects of traditional African food processing on carotenoid content of [beta]-carotene-rich maize and a rapid HPLC method for the quantification of carotenoids in maize

Abstract

<p>The effect of traditional African maize processing on the carotenoid content of [beta]-carotene-rich maize was investigated using a Ghanaian maize processing method and high performance liquid chromatograph (HPLC) analysis. The concentration of all-trans-[beta]-carotene decreased significantly from 5.44 ± 0.97 [mu]g/g to 3.56 ± 0.72 [mu]g/g (dry weight basis) after soaking, fermentation and cooking (P = 0.002). Retention of carotenoids in the raw maize kernels after soaking for 24 hours at room temperature ranged from 84.78 ± 10.68% for zeaxanthin to 75.1 ± 9.99% for all-trans-[beta]-carotene. When the unfermented dough obtained from the soaked ground kernels was stir-cooked for 9 min at 930C, the final total retention of carotenoids was 80.52 ± 13.33% for lutein, 81.44 ± 12.07% for zeaxanthin, 77.92 ± 9.97% for [beta]-cryptoxanthin, 73.98 ± 4.55% for [alpha]-carotene and 67.86 ± 8.92% for all-trans-[beta]-carotene. The final retention of all-trans-[beta]-carotene was 67.58 ± 8.01% when the raw dough obtained from the soaked kernels was fermented for 48 hours at room temperature. The final retention of lutein, zeaxanthin, [beta]-cryptoxanthin, [alpha]-carotene, and all-trans-[beta]-carotene in the cooked fermented dough was 63.8 ± 8.01%, 68.0 ± 11.78%, 70.3 ± 11.57%, 71.7 ± 5.68%, and 65.6 ± 7.64%, respectively. Retention of total [beta]-carotene (all-trans-[beta]-carotene plus cis- and trans-isomers) averaged 66.6 ± 7.41% after soaking, fermentation, and cooking. The vitamin A value of the raw maize kernels before soaking was 48.42 ± 8.3 [mu]g Retinol Activity Equivalents (RAE)/100 g which decreased to 13.39 ± 2.6 [mu]g (RAE)/100 g after soaking, fermentation, and cooking (wet weight basis). It was concluded that the vitamin A value of the finished product was decreased significantly during food processing.</p>