PREPARATION OF FRUIT JAM
Aim of Experiment: To learn the preparation of fruit Jam.
Objectives:
1. To describe the method of preparation and preservation of Jam.
2. To know the difficulties, precautions to be taken and technical knowledge of the final product quality.
Principle:
Jam is a product made by boiling fruit pulp with sufficient sugar to a reasonably thick consistency, firm enough to hold the fruit tissues in position. It can be prepared from a single or two or more kinds of fruits. Commercial Jams can be prepared from pieces of fruit, fruit scraping and pulp. Apple, pear, sapota, apricot, loquat, peach, papaya, karonda, carrot, plum, strawberry, raspberry, mango, tomato, grapes and muskmelon are used for the preparation of jams.
Jam is a very common product made out of fruits and vegetables that permit consumers to taste the fruits of their liking even during lean periods or when the fresh produce is expensive. These products also permit the diversification of the fruit used to avoid distress sales during the production season and to minimize post-harvest wastages. This practice of preparing Jam is very simple and could be attempted at household levels even in rural areas if adequate food safety-related precautions are put in place. Besides, there are several fruits that are not cultivated in large quantities to permit large-scale processing. Still, these fruits are novel enough to convert them into processed products like jam and present them to consumers.
Specification for Jam preparation: Jam contains 0.5-0.6% acid, less than 40% invert sugar and TSS of 68°Brix.
Raw materials, equipment and apparatus required:
1. Fruit/vegetable
2. Sugar
3. Peeler
4. Pulper
5. Filter
6. Cloth / sieve
7. Pans of suitable size
8. Heaters
9. Thermometer
10. Crown corking/ capping machine
11. Corks/ caps
12. Sterilizer/Pasteurizer
13. Volumetric flask
14. Measuring cylinder
15. Weighing balance
16. Potable water
Chemicals and reagents required:
1. Citric acid/ ascorbic acid
2. Potassium metabisulphite or Sodium benzoate
Procedure:
For the preparation of 10 kg of jam follow the procedure given below:
1. Calculate the amount of fruit pulp required as per commercial specification
2. Required pulp = (45/100) x 10 = 4.5 kg.
3. Measure the TSS using a refractometer (say the TSS is 50%)
4. Calculate the total solids content of the juice i.e. 0.5 x 4.5 = 2.25 kg.
5. The final required TSS content in the product is to be say 68%. The TSS required to be added to obtain the final product is (0.68 x 10 – 2.25) kg = 4.55 kg.
6. The amount of soluble solids in the form of citric acid and KMS is Citric acid @ 0.5%, in the final produce is 50 g i.e. 0.05 kg.
7. The amount of solids to be added in the form of sugar is 4.55–0.05=4.5 kg.
8. Add the calculated amount of pulp and sugar to about 2 litres 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.
9. Citric acid @ 0.5%, in the final produce, is 50 g i.e. 0.05 kg.
10. The amount of solids to be added in the form of sugar is 4.55–0.05=4.5 kg.
11. Add the calculated amount of pulp and sugar to about 2 litres 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.
Ingredients for 1 kg of Flavoured Papaya Jam: Papaya=1kg, Sugar=500-650g, citric acid=2g, required flavour and colour.
Observations
Amount of fruit taken =___________
Amount of edible fruit portion = ____________
Amount of Sugar taken =__________
Amount of Citric acid used =__________
Final amount of product =___________
PRECAUTIONS
1. Avoid overripe and microbiologically spoiled fruits.
2. Wash the extractors and other equipment with hot water to reduce the chance of infection.
3. Preserve the jam immediately after preparation in order to avoid quality deterioration and incidence of spoilage.