Levels of Β-Carotene and Microbial Load in Solar Dried Dark Green Leavy Vegetables of Different Moisture Content With Storage
Green vegetables such asAmaranthus and cowpea leaves constitute an indispensible constituent of human diet. They are rich sources of carotene, vitamin, riboflavin, folic acid, protein and minerals like calcium, iron and phosphorous. There are a lot of these vegetables in the market during the rainy season resulting in reduced prices and rottage leading to losses. Preservation of these greens can prevent huge wastages as well as make them available in the dry season at remunerative prices. This further aids in averting vitamin A deficiency in pregnant women and young children below the age of five years since these vegetables are a good source of β-carotene which is a pre-form of vitamin A. Up until now, programmes to combat vitamin A deficiency have been directed largely towards use of vitamin A supplements in hospitals during immunization and in foods which are mostly expensive and less effort has been directed towards locally available foods.This study was conducted to determinethe effect of moisture content and storage conditions on the levels of β-carotene and microbial load on solar dried dark green leafy vegetables with storage. The vegetable samples were evaluated for concentration of β-carotene and total microbial count at varied intervals of 1 week in the first month, 2 weeks in the second and third month and 4 weeks in the subsequent weeks. The moisture content were in the range of 7-13%. Moisture content was determined by weighing 0.5g of the ground sample in a dry pre weighed crucible and heated in an oven at 1100for 3 h. The contents were then cooled in the closed crucible in dessicator and the weight determined after attaining room temperature. The percentage moisture content was then determined by dividing change in weight by original weight then multiplied by 100. The storage conditions include inert, which was created by flushing vegetable samples in nitrogen gas. Modified atmosphere packaging (MAP), where an oxygen absorber was included in the vegetable pack and Normal, where there were no modifications in the storage condition. Extracts from vegetable samples were analysed by High Perfomance Liquid Chromatography. Elution was perfomed isocratically with systems of methanol:dichloromethane:water (79:18:3, v:v:v). Microbial count was determined by enumeration of colony forming units on inoculums. Fresh blanched vegetable leaves contained β-Carotene as follows; 65933.5-76275.5μg/ /100g DM for Cowpeas and 75627.5-96974.5μg/100g DM for Amaranthus. Minimum microbial growth was observed in vegetables stored under inert storage conditions at 7% moisture content (34cfu/0.5g) while maximum microbial growth was observed in vegetables stored under normal storage conditions at 13% moisture content (154cfu/0.5g). The effect of storage condition on level of β-carotene was significant (p<0.05), with storage under MAP showing the highest stability. The effect of moisture content on level of β-carotene was not significant (p>0.05). The effect of storage condition and moisture content was significant on microbial load (p<0.05). This study concludes that, storage under MAP at 7% moisture content improves stability of β-carotene with storage while ensuring microbial safety during consumption. The study recommends that during drying on a sunny windy day the vegetables be aired for 7h.