STUDY OF THE KINETICS OF DRYING DARK GREEN LEAFY VEGETABLES
Abstract
Nutrition plays a vital role in human health. Dark green leafy vegetables are rich in vitamins (especially K and folic acid), chlorophyll, antioxidants and other nutrients that support bone health, heart health and overall immunity. Dark green leafy vegetables include spinach, kale, arugula, romaine lettuce, Swiss chard, bok choy, sorrel, and turnip greens.
Folate is a water-soluble B vitamin that plays a vital role in cell growth and development. The names folic acid and folate come from the Latin word folium, meaning ‘leaf,’ and it was first isolated from spinach leaves in 1941.
Spinach (Spinacia oleracea L.) is an annual leafy green plant rich in beta-carotene (provitamin A), folic acid (vitamins A and C), minerals (phosphorus, sodium and potassium) and dietary fibre.
Sorrel (Rumex acetosa L.) is a perennial herbaceous plant with a high content of ascorbic acid and antioxidant properties; rich in minerals, vitamins and fibre; and also has a high protein content in its leaves.
Spinach and sorrel are vegetables that spoil quickly after harvesting and can only be consumed during the growing season. Drying is one method of preservation that extends the shelf life of these vegetables while preserving their vitamin content and preventing the growth and production of microorganisms that cause decay.
Dark green leafy vegetables are dried using the following methods: solar, convective, microwave, incineration, sublimation, convective-microwave, and others.
Convective drying is one of the most common methods for processing dark green leafy vegetables.
To stabilise folates, plant raw materials must be combined with raw materials that are high in vitamin C. Given that sorrel is high in vitamin C, it is advisable to add it to spinach to stabilise folates.
Therefore, the aim of this work is to study the drying processes of folate-containing raw materials based on spinach and sorrel.
The work involved conducting drying studies on an experimental convective bench using spinach, sorrel and mixtures based on these ingredients.
The results show that the drying time for these leafy vegetables is between 180 and 190 minutes at a heat transfer fluid temperature of 55°C. Creating a spinach-sorrel mixture allows you to preserve the folates found in spinach. Using high temperatures during drying accelerates the destruction of chlorophyll and folates, so it is advisable to use lower heat transfer parameters.
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