Simulated Bioaccessibility Studies of Beta-Carotene and Vitamin B Series in Selected Leafy African Indigenous Vegetables in Kisii County, Kenya
Moraa, Onyambu Zipporah
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Over two billion people worldwide are affected by various vitamin deficiencies resulting in poor health, low gross domestic product and high mortality rates. Deficiency of vitamins remain a public health problem in the developing countries affecting mostly expectant and lactating mothers as well as children under five years of age. Despite a number of approaches taken in managing these deficiencies, the nutritional approach is still most preferred and especially employing leafy African indigenous vegetables (LAIVs), which can be consumed either fresh or processed. In Kenya, LAIVs are locally available and inexpensive. Although they are good sources of vitamins and other nutrients, the LAIVs are underutilized and face postharvest losses in seasons of high availability. Sun drying and oven drying are among the methods employed to address postharvest losses. The research gap presented is on the in vitro bioaccessibility of beta-carotene (BC) and vitamin B series to support promotion of LAIVs when consumed as individual fresh, processed or as recipes of mixtures and formulations, among the forms in which they can be consumed. This would inform on the amount of the same nutrients that are potentially available for absorption in the gastrointestinal tract once ingested. In vitro methods are preferred for being accurate, reproducible and have no ethical constrains among others. The general objective was to investigate the bioaccessibility of beta-carotene (BC) and vitamin B series in LAIVs, recipes and formulations using an in vitro method. Levels of vitamins were determined in the fresh and processed LAIVs; Cleome gynandra, Vigna unguiculata, Amaranthus viridis, Basella alba and Cucurbita maxima by UV-Vis spectrophotometry for BC and high performance liquid chromatography (HPLC) for vitamin B series. Gastrointestinal digestion was performed for the gastric and intestinal phases. The data obtained was analyzed by SPSS employing ANOVA to compare the mean levels and percentage bioaccessibilities of the vitamins. The mean (n=3) levels (mg/100g DW) of BC and the vitamin B series were sufficient to meet the recommended dietary allowances (RDAs) and provided the mean range of % bioaccessibility of BC of 61.36±1.87 to 97.23±0.06 (fresh), 65.67±5.53 to 84.31±0.27 (boiled) and 16.97±0.02 to 48.19±0.82 (boiled-fried) and for vitamin B ranged from 5.17±0.93 to 100.00±0.01 (fresh), 5.18±0.87 to 100.00±0.01 (boiled) and 14.23±3.69 to 100.00±0.01 (boiled-fried). In recipes the range of the mean % bioaccessibility of BC was 69.09±1.29 to 88.97±0.22 (RCP1) and 17.45±6.47 to 25.30±1.05 (RCP2) while that of vitamin B was 19.97±3.57 to 100.00±0.00 (RCP1) and 5.57±1.18 to 92.57±0.62 (RCP2). In formulations the range of the mean % bioaccessibility of BC ranged from 48.28±3.66 to 70.45±0.78 while that of vitamin B was 6.28±0.21 to 97.20±2.01. Statistical differences (p<0.05) were observed between processes, recipes and formulations. Both the fresh and processed vegetables were found to contain levels of BC and vitamin B series that meet the RDAs as set by the World Health Organization (WHO). The findings show there is sufficient in vitro bioaccessible levels of BC and vitamin B series with processing of LAIVs therefore promoting their consumption would play a significant role in addressing malnutrition and food security.
- PHD-Chemistry