PREPARATION OF FRUIT JELLY

Aim of the Experiment: To understand and prepare the fruit Jelly.

Objectives:

1. To describe the method of preparation and preservation of Jelly.

2. To know the difficulties, precautions to be taken and technical knowledge of the final product quality.

Principle:

  A jelly is a semi-solid product prepared by boiling a clear, strained solution of pectin-containing fruit extract, free from pulp, after the addition of sugar and acid. A perfect jelly should be transparent, and well-set, but not too stiff, and should have the original flavour of the fruit. It should be of attractive colour and keep its shape when removed from the mould. It should be firm enough to retain a sharp edge but tender enough to quiver when pressed. It should not be gummy, sticky or syrupy or have crystallized sugar. The product should be free from dullness, with little or no syneresis (weeping), and neither tough nor rubbery.

Fruit jelly

Guava, sour apple, plum, karonda, wood apple, loquat, papaya, and gooseberry are generally used for the preparation of jelly. Apricot, pineapple, strawberry, raspberry, etc., can be used but only after the addition of pectin powder, because these fruits have low pectin content. 

Specification for Jam preparation: Its acid content should be 0.5-0.75% and TSS=65°Brix.

Raw materials, equipment and apparatus required:

1. Fruit

2. Sugar

3. Cloth/ sieve

4. Pans of suitable size

5. Heaters

6. Thermometer/ Refractometer

7. Crown corking/ capping machine

8. Corks/ caps

9. Sterilizer/Pasteurizer

10. Volumetric flask

11. Measuring cylinder

12. Weighing balance

13. Potable water

Chemicals and reagents required: 

1. Citric acid/ ascorbic acid

2. Potassium metabisulphite

3. Sodium benzoate

Method of preparation

For the preparation of 10 kg of jelly follow the procedure given below:

1. Take about 10 kg of fruit and boil in 15 lit of water for 20 – 30 min.

2. Add to it about 20 g (@ 2g/kg) of citric acid and strain it.

3. Determine the pectin content using alcohol or Jelmeter test.

4. Add the required amount of sugar (1:1 for extracts rich in pectin; 1:0.75 for extracts moderate in pectin; and 1:0.5 for extracts poor in pectin.

5. Boil the mixture and judge the endpoint using the sheet test as mentioned in the preparation of the jam.

6. Add the calculated amount of pulp and sugar to about 2 lit of water and boil it to 105°C so that the sugar dissolves completely. Add citric acid and juice to the sugar syrup and judge the endpoint by measuring its TSS or using a sheet test.

Flow sheet for Fruit Jelly preparation

Observations

Amount of fruit taken =___________

Amount of edible fruit portion = ____________

Amount of Sugar taken =__________

Amount of Citric acid used =__________

Final amount of product =___________

TSS of final product = _______

PRECAUTIONS

1. Avoid overripe and microbiologically spoiled fruits. 

2. Wash the strainers and other equipment with hot water to reduce the chance of infection. 

3. Preserve the jelly immediately after preparation in order to avoid quality deterioration and incidence of spoilage.