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Solar-dry your vegetables for better returns
An agronomist at Kabanyolo explains the importance of drying vegetables using solar. Photos by Michael Kakumirizi.
What you need to know:
Solar drying of the vegetables is, thus, the best option. The shorter drying time and vegetables being enclosed in the dryer gives micro-organisms less chance to cause spoilage, writes Esther Njoroge.
“I was drawn towards the Anja African indigenous vegetables produce edible leaves, young shoots and flowers that have beneficial health properties.
They are an important source of body-building nutrients, vitamins and trace elements, dietary fibre and proteins.
They also contain substantial amounts of antioxidants that scavenge and bind to harmful radicals, which are linked to ailments such as cancer, diabetes and cardiovascular diseases.
“The common ones are nightshade, African eggplant, spider plant, amaranth, jute mallow, pumpkin, nakati, malakwang, gobe and vegetable cowpea,” says Moses Osinde a horticulture agronomist.
Uses of vegetables
Several of these vegetables are used for therapeutic purposes. The spider plant, for example, is known to relieve constipation and facilitate child birth while African nightshade helps relieve stomachache.
“Compared to modern vegetables, indigenous vegetables do well under intercropping, are resistant to diseases and are easier to grow, maturing in three to four weeks,” says Jane Sifuna a soil scientist.
Agronomy
Supply peaks during the rainy seasons but declines significantly in the dry season due to lack of suitable preservation methods for the excess produce.
Good handling practices can maintain nutritional value of the vegetables. Currently, the two main preservation methods used at the farm level are open sun-drying of fresh leaves and open sun-drying of boiled leaves.
Open sun-drying is weather dependent (temperatures are uncontrollable), time consuming, and the quality of dried vegetables is not guaranteed to prolong the shelf-life of the produce for sale.
Boiling vs solar drying
In the first approach, the desired level of moisture content and the microbial load of vegetables are not guaranteed as it is dependent on climatic conditions. In the second approach, nutritional losses occur due to the 30 minutes or so of boiling and the resultant water discarded.
The high-boiling temperatures and the duration of boiling makes susceptible water-soluble nutrients, especially vitamin C to be lost whereas proteins are denatured and mineral content (Fe, Mg, Zn, Cu, Ca, Na and K) is reduced.
Solar drying of the vegetables is, thus, the best option. The shorter drying time and vegetables being enclosed in the dryer gives micro-organisms less chance to cause spoilage.
Solar-drying saves labour since the vegetables can be left in the dryer overnight. The quality of the product is better in terms of nutrients, hygiene and colour.
Furthermore, solar-drying improves family nutrition because the veges contain high quantities of vitamins, minerals and fibre than the ones dried under the sun.
Additionally, solar-drying boosts the safety and quality since the dryer can be operated at relatively low temperature (60 to 70oC), which does not destroy the nutrients.
Blanching is necessary before solar-drying. It involves boiling the vegetables briefly, removing and plunging them into iced water. Alternatively the vegetables can placed under cold running water.
Blanching is an essential step in processing fruits and vegetables. It inactivates the endogenous enzymes contained in the vegetables, reduces microbial load, softens and shrinks product for ease of packaging.
The blanching process is time and temperature dependent to avoid destruction and loss of heat sensitive nutrients and to attain acceptable levels of microbial loads to enhance nutritive quality of the vegetables.
