Processing of Horticultural Crops (1+2)

Exercise

Practical 20 - Preparation of Jam

Aim: To prepare Jam from different fruits.

Theory: Jam is prepared by boiling the fruit pulp with a sufficient quantity of sugar to a thick consistency, firm enough to hold fruit tissues in position. For preparation of jam not less than 45 parts of fruits are used for every 55 parts of sugar. According to FPO specifications, minimum quantity of soluble solids in the prepared jam shall not be less than 68% (w/w). The jam prepared by using two or more fruit pulps, is called as mixed fruit jam. Approved fruit colour and flavour can also be added into the jam when declared on the label.

Raw material, ingredients and utensils required

1. Fruits like Apple, apricot, mango, plum, peach, guava, pineapple, pear and kiwifruit etc either singly or in combination.
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 20.1.

Table 20.1 Recipe for preparation of jam from different fruits (basis 1 kg fruit pulp)

Fruit	Sugar, g	Citric acid, g
Apple	750	2.0
Apricot	600	1.0
Mango	750	1.5
Plum	750	-
Peach	800	3.0
Pear	750	1.5
Strawberry	750	2.0
Aonla	750	-
Mixed jam (equal amount of fruit pulp)	800	2.5

Procedure for preparation of jam: The jam from different fruits is prepared by using the steps as given in flow sheet (Fig 20.1) and discussed as under:

Sheet or flake test: A small quantity of jam is taken out during boiling in a spoon or wooden ladle. It is allowed to drop after slight cooling. If the product falls off like a sheet instead of flowing like syrup, indicates the end point. Otherwise, continue boiling till the sheet test is positive. OR
A drop of prepared jam if poured gently in glass tumbler full of water settles down at the bottom of tumbler also indicates the end point. In case of shattering in water further cooking is needed.

Weight Test: Generally from one kg sugar and one kg pulp approximately one and half kg jam is obtained.

Procedure for jam preparation
1. Select fully ripe fruits and wash thoroughly to remove any adhering dust and dirt.

2. Peel the washed fruits slice and cook till softening and extract the pulp. Preserved pulp can also be used for jam making.

• Mangoes are peeled, stones separated and then sliced. The slices are then passed through a pulper.
• Pineapples are peeled, sliced and the cores punched.
• Apple, guava and pear after washing are cut into halves or quarter, boiled till softening and pulp extracted in a pulper.
• Peach, plum and apricot was washed, boiled like softening and pulp extracted in a pulper.

3. Addition of sugar: Add continue cooking with stirring. Generally 55 parts of cane sugar (sucrose) is used for every 45 parts of fruit for preparation of jam.

4. Citric, tartaric or malic acid are used to supplement the acidity of the fruit for jam making. (Generally 5 g citric acid for each kg of sugar used is added to the jam). Flavours are added at the end of cooking process and just before packing.

5. Only permitted colours are added not exceeding 100 ppm limit as per the Indian Food Laws.

6. Cook the mixture slowly with occasional stirring with a small quantity of water to facilitate pulping. After addition of sugar, the mixture is boiled rapidly to concentrate the soluble solids to about 68.5% in a pan made of stainless steel or aluminium.

7. Add pectin (5 g for each kg of sugar used) in powdered or liquid form just before the end point if jam is made from preserved pulp.

8. Determine the end point of jam by using a jelmeter test, ladle test or sheet test or weight test.

9. Fill the prepared jam while hot in glass jars.

10. Allow the product to cool and seal the jar air-tight. A layer of molten paraffin wax can be placed at the top of cooled jam which helps in preservation. When paraffin wax solidifies, place the lid on the jar.

11. Label and store in a cool and dry place.


FPO specifications for Jam

Fruit contents	Not less than 45% Except Raspberry and strawberry jam where it shall be not less than 25%
Total soluble solids	Not less than 68% (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