Raw materials, equipment and apparatus
1. Fruit/vegetable, sugar
2. Peeler
3. Pulper
4. Filter cloth / sieve
5. Pans of suitable size
6. Heaters
7. Volumetric flask
8. Weighing balance

Chemicals and reagents
  1. Citric acid / ascorbic acid
  2. Potassium metabisulphite (KMS)
  3. Sodium benzoate

Theory: - Jelly is a semi solid product prepared by boiling a clear strained solution of pectin containing fruit extract free from pulp. After addition of sugar and acid a perfect jelly should be transparent well set, but not too stiff and should have the original flavor of the fruit.

Procedure

  1. Selection of fruit: - In preparation of jelly the main step is selection of fruit. The fruit are select deep color, mature fruit and fruit can not be over ripe.
  2. Washing: - The fruits are washed with clean or plane water
  3. Cutting into thin slices
  4. Boiling with water for extraction of juice
  5. Addition of citric acid during boiling
  6. Straining of extract
  7. Addition of pectin: - We know pectin is structural component of jelly. We should be careful while addition of pectin. Some pectin is already present in fruit so first its amount is detected and then rest is added. Because high quantity of pectin may give a firm and tuff jelly if it is less the jelly may fail to set. 0.5 to 1% pectin of good quality can be used.
          Pectin Test
            (a) Alcohol test: - In which the alcohol are add in the juice extract if clump form, the pectin is high, if                  fragment form, the pectin is medium and if dissociates form the pectin is low.
            (b) Jell meter test: - In which the juice are filed in jell meter allowed to flow in specific time and amount of extract is noted and then calculate.
  1. Addition of sugar: - 0.75/kg of sugar is added in 1 liter of extract there should be excess addition of sugar. It too much sugar is added it result in a syrupy or highly soft jelly
  2. Cooking: - In preparation of jelly cooking should not be below the end point. If the cooking is stopped before the total soluble solid reaches 65%. The jelly may remain syrupy and highly soft jelly should not be cooked beyond.
  3. Addition of sugar: - 0.75/kg of sugar is added in 1 liter of extract there should be excess addition of sugar. It too much sugar is added it result in a syrupy or highly soft jelly.
  4. Judging of End Point: - Boiling of jelly should not be prolonged, because excessive boiling results in greater inversion of sugar and destruction of pectin. The end point can be judged by sheet test, drop test, refractometer, and thermometer.
    • Refractometer method
    • Temperature test
  1. Removal of scum: - We have to add one tea spoon full of edible oil added for 45 kg sugar. If the scum is not removing the jelly become cloudy. When the scum is not removed before pouring.
  2. Addition of  color and preservatives
  3. Filling in sterilized jar: - The hot solution is poured into sterilized container. So as to reduce the time of contact b/w pectin acid and boiling sugar.
  4. Sealing: - The container is sealed by air tight sealing machine.
  5. Storing: - This is the last step in processing of jelly. The container is stored at 25 to 35 degree C (at ambient temperature).

Problems in Jelly Making
The most important difficulties that are experienced are as follows:
• Failure to set: This may be due to the addition of too much sugar, lack of acid or pectin, cooking below/ beyond the end-point.
• Colour changes: Darkening at the top of the jars can be caused by storing them in too warm place or by an imperfect jar seal.
• Gummy jelly: It is the result of prolonged or over cooking in which more than desired inversion of sugar occurs
• Stiff jelly: Over cooking or using too much pectin makes too tough jelly which fails to spread when applied on bread.
• Cloudy or foggy jellies: It is due to the use of non-clarified juice or extract, use of immature fruits, over-cooking, over-cooling, non-removal of scum, faulty pouring, and premature gelation.
• Formation of crystals: It is due to addition of excess sugar and also due to the over-concentration of jelly. This excess sugar comes from over cooking, too little acid or from under cooking.
• Presence of mold: Due to imperfect sealing and insufficient sugar.
• Colour fading: This is due to high temperature and bright light in storage room. Another possible cause could be the insufficient processing to destroy the enzymes affecting colour.


According to FPO Jelly should contain


  • Acid                                                                                                    0.5-0.75%. 
  • Permitted quantity of Benzoic Acid Parts per million (ppm)                                                  Jams, marmalades, preserves, canned cherry, fruit jelly                         200ppm
  • Permitted quantity of Sulfur dioxide                                                                                        Fruit jam, jelly, and marmalade                                                              150ppm
  • Minimum % of TSS in final product                                                 65
  • Minimum % of prepared fruit in final product                                 45
  • Pectin                                                                                                 1%
  • Sugar                                                                                                  60 to 65%
  • Water                                                                                                  33 to 38%.