Processing of Horticultural Crops

Exercise

Practical 22 - Preparation of Marmalades

Aim: To prepare marmalade from citrus fruits.

Theory: Marmalade is a fruit jelly in which the slices/shreds of peel are suspended. The marmalades are prepared generally from citrus fruits like orange and lemon. The pectin and acid contents of the marmalades are kept slightly higher than that for jellies. They shall contain minimum of 45% fruit and 65% total soluble solids.

Raw material, ingredients, machinery required

1. Orange and lemon like citrus fruits are used for making marmalade.
2. Stainless steel knives, utensils for cooking and mixing, muslin cloth, glass jars, sterilization tank, gas bhatti etc.
3. Sugar (1:1), Citric acid 1g, shredded peel of orange 62g and flavour.

Procedure for preparation of marmalade
The marmalade is prepared by using the steps as given in flow sheet (Fig 22.1) and discussed as under:

1. Wash orange and lemon fruits in water and remove the thin peel.
2. Cut peel into thin fine shreds using knife or shredding machine.
3. Cut the peeled fruit into slices (0.3-0.45 cm thick) or crush into rough pulp.
4. Boil slices gently for 30-45 minutes by simmering with 2-3 times its weight of water to extract the pectin.
5. Test the extract for pectin by using alcohol test.
6. Clarify or strain the extract by passing through muslin cloth or use filter aid like wood pulp or flo-supercel or use filter press to get cleanextract. .
7. Cut peel into 1.9-2.5cm long and 0.8-0.12cm thick shreds using knife or shredding machine.
8. Soften these shreds by boiling in water for 10-15 minutes or in 0.25% sodium carbonate solution or by autoclaving at 10-15 psi steam pressure (116-121^oC).
9. Boil the extract along with sugar (1:1) to about 103^oC temperature.
10. Add prepared shreds to the boiling mixture.
11. Continue boiling to jellying end point (check by using sheet test, drop test, weight or temperature test), total boiling time shall not exceed 20 minutes.
12. Cool marmalade in a shallow pan with gentle straining to keep the shreds uniformly distributed in the marmalade. During cooling, orange peel oil can be added as an essence.
13. Fill cooled marmalade in pre-sterilized glass jars.
14. Place the layer of molten paraffin wax on the top surface of the jar.
15. Cover the jars with lug type lids and store in a cool and dry place.

FPO specifications for marmalade

Fruit content	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

* Sheet 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. Falling of the drop in the form of flakes or sheet indicates the end point.