Improving the preservation, marketability and utilisation of traditional Ghanaian leafy vegetables for use as sources of micronutrients

Abstract

This is a baseline report on some of the traditional leafy vegetables (TLVs) used in Ghana. Amaranthus spp., Corchorus spp. and Hibiscus sabdarrifa occupy between 50 - 60 % of land allocated for vegetable cultivation in the study areas in the dry savannah parts of Ghana. Production, however, suffers from lack of planting/high yielding seeds, weeds, insect pests and lack of official research and development supports. Post-harvest management is poor in most places. With the high rate of wilting and the lack of appropriate storage techniques, the resulting poor keeping quality of all three TLVs is one of the biggest worries of almost all the farmers. Sun drying was the only preservation technique employed to improve shelf lives. Unfortunately, this was done mainly on uncemented floors where rodents and domestic animals like goats, fowls and sheep have easy access. Consumer preference for the three TLVs varied from place to place. Whilst at the Kumasi Central Market, the order of marketability of the three TLVs, used as a proxy for consumer preference, was Corchorus spp >Amaranthus spp> Hibsicus sabdariffa, the order, however, reverses at the Tamale Central Market. Unlike the latter market, the three TLVs were poorly integrated into the mainstream marketing of vegetables at the Kumasi Central Market. The marketing of TLVs had an unfortunate socio-cultural bias. Different ethnic groups specialised in the sale of TLVs that are preferred by their communities. At most markets in the south, whilst the marketing of the leaves of cocoyam, Xanthosoma maffafa, the most popular TLV in the forest zone, is widespread, that of the three popular dry-savannah TLVs was limited and handled mainly by traders of northern Ghana descent. Market women from the south wrongly perceived these TLVs as weeds; a major obstacle to the general use of these TLVs. When the three TLVs were minimally processed, sealed-packaged in low-density polyethylene bags, with perforations, and stored at 5-8 °C and 80-85 % RH for a period of 18 days, the order of increasing shelf-life obtained for the three TLVs was; Hibsicus sabdariffa (3 days), <Amaranthus viridis (by 6 days) and Corhorus olitorius (by 10 days). Though most households in the north consume these 'leaves about 4 to 5 times in a week, the drudgery and cumbersome processes involved in the using these TLVs in the preparations of traditional dishes as well as the undesirable sensory characteristics such as the taste, especially if not well cooked, were identified as the main obstacles to increased use of the TLVs. Initial traditional parboiling of the leaves before being used resulted in considerable losses of micronutrients. The worst was Corhorus o/itorius, which lost 15 % vitamin A, 40 % of vitamin C, 20 % of iron and 40 % of zinc when parboiled for 30 minutes and water strained off. Though solar dehydration considerably reduced drying time and microbial load, it affected micronutrient retention ratio, colour and therefore, general quality of the TLVs. TLVs from the dry-savannah parts of Ghana are not widely used in the cities of Ghana. Only 10 % of respondents (n= 200) of the two major cities in Ghana claim to be using the TLVs occasionally. This means that there is an urgent need to create national awareness of the nutritional values of these TLVs