Processing of Horticultural Crops (1+2)

Exercise

Practical 21 - Preparation of Jellies

Aim: To prepare jelly from guava fruits.

Theory: Jelly is prepared by boiling the fruit with or without addition of water, straining the extract and mixing the clear extract with sugar followed by boiling the mixture to a stage at which it will set to a clear gel. The jelly should be transparent, well set, but not too stiff and having original flavour of the fruit. It should be attractive in colour and should keep its shape. In the preparation of jellies, pectin is the most essential constituent. As per FPO specifications, the quantity of fruit and soluble solids in the final product shall not be less than 45 and 65 percent (w/w) respectively. Guava jelly is the commercial product available in the market however jelly can be prepared from sour apple, karonda, jamun, loquat etc.

Raw material, ingredients, machinery required

1. Guava, sour apples, karonda, loquat etc are used for making jelly.
2. Stainless steel knives, ladle utensils for cooking and mixing, glass bottles, sterilization tank, juicer/basket press, bhatti/LPG stove/boiler, Refractometer etc.
3. The recipe (for 1kg fruit pulp) for different fruits is given in Table 21.1.

Table 21.1 Recipe for preparation of jelly from different fruits.

Fruit	Quantity	Sugar, g	Citric acid, g
Sour Apple	1kg	750-1000	3.0
Guava	1kg	750	3.0
Karonda	1kg	750	-
Jamun	1kg	750	1.0
Loquat	1kg	800	2.0

Procedure: Jelly is prepared from different fruits by using steps as detailed in Figure 21.1 and method for guava jelly is explained as under:-

Preparation of guava jelly

1. Select sound, mature fruits, wash thoroughly and cut them in small pieces along with peel (peel contains maximum pectin).
2. Cover the pieces with water and add citric acid 1.5 to 2 g/kg fruits.
3. Boil the mass gently to enable release of pectin.
4. Repeat the process 2-3 times for complete extraction of pectin.
5. Strain the mass through a muslin cloth to separate the extract.
6. Do not squeeze, only strain all the extracts and allow it to stand for settling.
7. Collect only the supernatant.
8. Perform pectin test by adding two teaspoonful of rectified spirit to a teaspoonful of extract. Formation of one big clot indicates high pectin in the extract, formation of many clots indicates medium pectin and thin gelatinous precipitates indicates poor pectin.
9. If the pectin contents are poor, concentrate the extract till it gives test of high pectin or add the pectin externally.
10. To prepare jelly from the extract cook till end point reaches. The end-point of a jelly can be judged by using any of the following methods:

• Cold plate test: A drop of the boiling liquid from the pan is taken and placed on a plate and allowed to cool quickly. If the jelly is about to set, the mixture on the plate will crinkle when pushed with a finger.
• Sheet or flake test: This test is more reliable than the plate test. A small portion of jelly is taken with a large spoon or wooden ladle, cooled slightly and then allowed to drop off. If the jelly drops like syrup, it requires further concentration, but if it falls in the form of flakes or sheet, the end point has been reached.
• Temperature of boiling mixture: The temperature of boiling jelly during end point generally corresponds to 105.5⁰C.

11. Pour the finished jelly into clean, dry, pre-sterilized jars kept on a wooden board to prevent breakage.
12. Allow the product to cool and seal the jar air-tight.
13. A layer of molten paraffin wax can be placed at the top of cooled jelly which helps in preservation.
14. Label and store in a cool and dry place.

FPO specifications for jelly

Fruit contents	Not less than 45%
Total soluble solids	Not less than 65% (w/w)
Preservatives	Sulphur dioxide (Not more than 40 ppm) Benzoic acid  (Not more than 200 ppm)
Synthetic sweetening agents	Not permitted
Fermentation test	Negative
Organoleptic test	Retain flavour of original fruit and free from burnt or other objectionable flavour
Crystallization	Absent