Vitamin A content in the traditionally preserved indigenous vegetables: a case study of Koru location, Nyando district
Manuche, Winnie Enid
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In Koru Location indigenous vegetables grow well during the rainy season but remain scarce in the dry season.The indigenous vegetables are usually preserved and stored for use during the dry season. However, vitamin A deficiency is still a problem in the area-affecting children of six years of age and below. The present study investigated the methods used in preserving indigenous vegetables and determined the beta-carotene and thus vitamin A content in them. Field data on types of indigenous grown, the extent of their preservation and the methods used for preservation were collected through interviews using a semi-structured questionnaire administered to a sample of 60 women residing in the study area, as well as through observation. Beta-carotene content in the preserved vegetables was determined using a spectrophometric procedure. Beta-carotene was extracted in an organic solvent, purified by passing through a column and absorbance read at 451nm. The results showed that eleven types of indigenous vegetables are grown in Koru Location out of which five types, namely cowpea leaves, spider herb, bush okra, black nightshade and pumpkin leaves are usually preserved for use during the dry season. Sixty three percent of women are involved in the preservation of vegetables. There was a significant difference in the age of mothers who preserved vegetables and those who did not, with mothers of over 46 years preserving vegetables more than younger mothers (p=0.0005). The methods used to preserve vegetables included sun drying, fire drying and fermentation. Sun drying of vegetables takes one to three days depending on the amount of sunshine available and the pre-treatment method of the samples. The sun-dried vegetables are kept for a period of up to 8 months though the majority of mothers keep them for 6 months (55%). Fermented vegetables are kept for a shorter time (maximum of 7 days). The sun dried indigenous vegetables contain significantly lower amounts of beta-carotene as compared with fresh vegetables (p=0.002). The fresh vegetables lost between 29-74% of their beta-carotene content on sun drying. After 6 months of storage there was a further significant decrease in the beta-carotene content in the sun dried and stored vegetables (p=0.003), losing about 62-68%. However, solar drying was found to retain more beta-carotene in the vegetables than sun drying (p=0.001). It can be concluded that the indigenous vegetables grown and preserved in Koru Location contain high amounts of beta-carotene (provitamin A) that can be used to prevent vitamin A deficiency. The preserved vegetables retain very low concentrations of beta-carotene after 6 months of storage.