Drying of Vegetables
Drying of Vegetables
The steps in the dehydration of vegetables are preparation (washing, peeling and slicing), balancing, sulphating and drying. Blanching may be carried out either in boiling water or in steam, but in the case of green vegetables like green peas, split field beans, spinach and fenugreek leaves, blanching in boiling water containing 0.1% magnesium oxide, 0.1% sodium carbonate and 0.5% potassium metabisulphite (KMS) is recommended to ensure maximum retention of natural green colour in the dehydrated vegetables. In other case, sulphating may be carried out immediately after blanching by steeping in half the weight of KMS solution of appropriate (0.1 to 0.25%) concentration, while beet root is not sulphated. Onion and garlic are neither blanched nor sulphated. For drying, generally 5-10 kg material is loaded per sq. m. of the area in trays.
Table: Schedule for Drying of Vegetables:
| Sr. No. |
Vegetables |
Preparation |
Pre-treatment |
Max. Drying Temp (Degree C) in home drier |
|
1 |
Potato |
Peel and cut in 1 cm thick slices |
Blanching in boiling water or steam for 3-4 min and sulphate in 0.125% potassium metabisulphite (KMS) soln for 10 min using 0.5 kgs of soln per kgs of slices |
65 |
|
2 |
Cabbage |
Remove outer leaves, cores and cut into 4-8 mm thick shreds |
Blanching in boiling water or steam for 3-4 min and sulphate in 0.25% potassium metabisulphite (KMS) soln for 10 min |
55 |
|
3 |
Onions |
Remove top and tails, peel and cut into 4-8 mm thick shreds |
Nil |
55 |
|
4 |
Okra |
Remove both ends with stainless steel khif and cut into 6 mm thick slices |
Blanching in boiling water or steam for 3-4 min and sulphaite in 0.25% potassium metabisulphite (KMS) soln for 10 min |
60 |
|
5 |
Bitter Gourd |
Remove both ends with stainless steel khif and cut into 6 mm thick slices |
Blanching in boiling water or steam for 8 min |
60 |
|
6 |
Green Pea |
Remove pod and prick with small nail or pin |
Blanch 3-4 min in boiling water containing 0.5% KMS, 0.1% Magnesium Oxide and 0.1% Sodium Bicarbonate |
60 |
|
7 |
Spinach |
Sort, wash thoroughly and cut in to 10-12 mm portions using a stainless steel knife |
Blanch 2 min in boiling water containing 0.5% KMS, 0.1% Magnesium Oxide and 0.1% Sodium Bicarbonate |
60 |
|
8 |
Fenugreek Leaves |
Sort, wash thoroughly and remove stalks and stem |
Blanch 2 min in boiling water containing 0.5% KMS, 0.1% Magnesium Oxide and 0.1% Sodium Bicarbonate |
60 |