Vegetables can be preserved through drying. In Comparison to fruits, vegetables contain less acid, so they are dried until being crisp, with a moisture content of about 10%. At this stage, microorganisms cannot proliferate.
1. Preparing vegetables
To prepare vegetables for drying, it initiates with washing them under cool water to remove dirt and chemicals on the surface. Then, they are into pieces or slice them thinly according to the guidelines for each specific type of vegetable. It is noteworthy to remove any tough fibers, woody parts, or cores if necessary and discard any damaged or discolored parts. The vegetable pieces should be cut evenly to ensure uniform drying. A food slicer or food processor can be used to prepare a large quantity at once.
2. Blanching vegetables:
Blanching is a necessary step in the drying process to stop enzyme activity, which can cause loss of colour and flavour in the vegetables during drying and storage. Blanching also helps shorten the drying time and rehydration time by loosening the cell structure, allowing moisture to escape and be absorbed more quickly.
Blanching in water: fill 2/3 of a pot with water, cover, and bring to a boil. Place the vegetables in a basket and dip them into the boiling water. Cover and blanch for the specified time, starting the timer when the water comes back to a boil. If it takes more than a minute for the water to return to a boil, it means too many vegetables were added; reduce the amount for the next batch.
Blanching with steam: Use a deep pot with a tight-fitting lid and a basket to keep the vegetables above the water. Boil the water and place the vegetables in the basket which is less than 50mm deep, to allow steam to circulate freely around the vegetables. Cover and steam according to the guidelines.
3. Cooling and drying vegetables:
After blanching, vegetables are immersed in cold water and rinse immediately when they are only slightly warm to the touch. Then, place them on a prepared drying tray and dry. The residual heat after blanching helps kickstart the drying process.
4. Determining vegetables dryness:
Vegetables should be dried until they are crisp, or "snap dry." Some types of vegetables may crumble when struck forcefully. At this stage, the moisture content in the vegetables is about 10%. Due to the high level of dryness, vegetables do not need to be conditioned (cooled) like fruits