| dc.description.abstract | This study was conducted to determine the effect of fermentation, solar drying and
storage duration on the levels of anti-nutrients: nitrates, oxalates and phenols, in
cowpea leaf vegetables. The rationale was reduction of the anti-nutrients. Reduction
of nutritional stress factors in plant foods increases bioavailability of nutrients, hence
improving their quality as foodstuffs. The cowpea leaves were purchased from the
local markets, sorted to remove blemished leaves and foreign materials, washed in
running tap water. Then, the vegetables were drained and divided into three batches of
16 kg each. One batch was heat-treated in hot water for 3 minutes and then cooled to
ambient temperatures, drained and solar-dried. The second portion was acidified to a
pH of 3.8, heat-treated, and solar-dried. The third portion was fermented for 21 days,
heat-treated, and solar-dried. The three batches of vegetables were spread at different
times on drying trays at the rate of 4 kg/m2 and dried in a solar drier to an
approximate moisture content of 10%. The dried vegetables were packaged in either
polyethylene bags or Kraft paper bags and stored for three months at 18oC, 22o- 26oC
or 32oC. Fermentation, heat-treatment and drying of vegetables led to significant (P <
0.05) reduction in nitrates compared to fresh cowpea leaves, but the reduction in
oxalates and phenols was not significant. Storage for three months led to significant
(P < 0.05) reduction in nitrates in the fermented sample compared to the other
samples. The acidified sample had significantly (P < 0.05) higher levels of phenols
after three months of storage than the other samples. Samples stored at 18oC had
higher levels of oxalates and phenols but lower levels of nitrates, compared to those
stored at higher temperatures. Packaging material had no significant effect on the
level of nitrates, oxalates and phenols. Data obtained in this study reveal a novel
technique for the reduction of anti-nutrients in cowpea leaf vegetables, namely;
fermentation followed by solar drying. The increased acceptability of these
fermented-dried vegetables would help rural communities in providing better
foodstuff with fewer anti-nutrients, thus alleviating micronutrient malnutrition. This
novel long-term storage technology can greatly help to deal with the issue of
seasonality and will increase food security, especially during the dry season. | en |
