Jam preparation

1. Presented by : S.SHARVESH M.Sc. HORTICULTURE
Department of Horticulture
ANNAMALAI UNIVERSITY

2. 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 one kind of fruit or from two or more kinds . Jam contains 0.5-0.6 per cent acid,0.5-1% of pectin and sugar should not be more than 40 percent and TSS 68%.

3. Jam means the product prepared from sound, ripe, fresh,dehydrated, frozen or previously packed fruits including fruit juices, fruit pulp, fruit juice concentrate or dry fruit by boiling its pieces or pulp or puree with nutritive sweeteners namely sugar, dextrose, invert sugar or liquid glucose to a suitable consistency. It may also contain fruit pieces and any other ingredients suitable to the products.

4. It may be prepared from any of the suitable fruits, single or in combination.
It shall have the flavour of the original fruit(s) and shall be free from burnt or objectionable flavours and crystallization.

5. History Culinary matters of cookbook of 1 st century Rome has the recipes to make jam. It was used as a diet in Middle East where there is ample amounts of sugar. In Britain, it was brought by Crusaders. It reached to West Indies by Spanish where the fruit was found in abundance and this method was used to preserve fruits.
The US immigrants have their own recipes of making jam but the book was prepared on 17 th century. In New England, honey, molasses and maple sugar was used to provide the sweet taste.

6. Health Benefits of Fruit Jam It does not have fat and cholesterol which helps to gain a healthy weight.
The pectin helps to lower the chances of cancer and promotes the health of skin, hair, bones and finger nails.
It also lowers the chances of getting stroke, heart attack and cardiovascular ailments.
It also lowers the developments of cancers in stomach, mouth and colon rectum.
It reduces the chances of spina bifida, neural tube defects and anencephaly in pregnant women.

7. One tablespoon of jam contains 56.9 calories, 0.07 g of protein, 0.01 g of total lipid fat, 0.05 g of ash, 13.77 g of carbohydrate, 0.2 g of dietary fiber 9.7 g of total sugars.

8. It also provides 0.02 mg of copper, 2.8 mg of vitamin C, 0.1 mg of iron and 0.015 mg of vitamin B2.

9. Proportion of high quality jam

10. Equipment required Sharp stainless steel knife
Weighing scales (large and small if available)
Plastic bowls
Cooker or stove
Boiling pan (stainless steel or aluminum)
Spoons for measuring Wooden spoon for stirring

11. Sugar thermometer
Refractometer
Jars and lidsLabels

12. Inspection (sorting) Ripe firm fruits received for jam production are sorted and graded according to their color, sensory appeal. Spoiled fruits are removed from the lot. This can be done using hand picking, color sorters. Suitable Fruit may be rich in acid and pectin content Overripe and green fruits, if used, adversely affect the quality of the jam The variety and maturity of the fruit and locality of cultivation influence the flavor and keeping quality of its jam

13. Washing Diseased, damaged or decayed fruits are rejected or Trimmed. For effective washing of fruits, 10 to 200 ppm of chlorine can be used in water. pH and temperature should be maintained, to prevent fruits from getting damaged or bruised. Dump and spray washers can be used in industries.

14. Fruit preparation The fruit is washed thoroughly to remove any adhering dust and dirt. The fruit is then subjected to preliminary treatment which varies with the type of fruit. Strawberries are crushed between rollers; raspberries are steamed, crushed and passed through sieves to remove the hard cores. Plums, peach and apricots are heated with a small quantity of water until they become soft and are then passed through a wide mesh sieve to separate the stones. Fruit after softening by boiling with small quantity of water can be passed through the pulper to extract the pulp.

15. Pears are peeled, cored and cut into small pieces. Mangoes are peeled, stones separated and then the slices are passed through a pulper. Pineapples are peeled, sliced and the cores punched. The slices are then cut into smaller pieces and passed through a screw type crusher to get a fairly coarse pulp suitable for making the jam.

16. Common fruit suitable for jam making Berries – Raspberry, Strawberry and Blueberriess
Drupe – Mango and Plums Stone fruits - Apricot
Pome fruits – Apple and Pear Citrus – Orange and Kumquat Papaya
Pineapple Cherry

17. Guava
Chiku
Grapes Some vegetables also added in jam Carrot
Tomato Muskmelon Watermelon Pumpkin

18. Peeling Fruits can be hand peeled as in case of citrus and apple, mechanical peelers and automated peeling machines containing blades are generally used in industries. Some fruits don’t require peeling. Pitting is sone in fruits containing hard inner stones.

19. Pulping Pulping is done to remove seed and core part. Skin can be removed and the fruit can be sliced before pulping Various pulping machines are available in market for fruits such as mangoes, peaches, tomatoes, bananas, draw berries and celeries etc. The gap between the sieve and rotor can be adjusted to suit different type of size and qualities of materials to be pulped.

20. Addition of sugar Generally 45 parts of cane sugar (sucrose) is used for every 55 parts of fruit for preparation of jam. The prepared jam should contain 30 to 50 percent invert sugar to avoid crystallization of sugar in the jam during storage. If the percentage of invert sugar (reducing sugar) is less than 30, then jam develops crystallization and if it is more than 50%, the jam will develop into a honey like mass due to the formation of small crystals of glucose. pH of the mixture of fruit should be 3.1 before sugar is added.

21. Sugar should not be added in excess as jam with higher total soluble solids becomes gummy and sticky.

22. Boiling The fruit is placed in the boiling pan along with a small quantity of water to facilitate pulping. It is then cooked sufficiently to liberate the pectin. After addition of sugar, the mixture is boiled to concentrate the soluble solids to about 68.5 percent and also to allow the necessary degree of inversion of the sugar. Boiling can be performed in steam jacketed kettle or stainless steel or aluminium boiling pan.

23. Boiling in a vacuum pan using reduced pressure is used to prepare jam at lower temperature (65-75°C) to minimize undesirable changes and for retention of vitamin.

24. Addition of acid, colour and flavour Citric, tartaric or malic acid are used to supplement the acidity of the fruit for jam making. Addition of acids to fruits which are deficient in acid is required to get appropriate combination of pectin, sugar and acid for proper setting of jam. Only permitted edible food colours should be used and these should be added towards the end of the boiling process. Flavours are added at the end of cooking process and just before packing.

25. Colours – Natural and Synthetic food colours
Nature colours obtained from some fruits and vegetables Red colour – Kokum , strawberry and red cherry (Veg – Beetroot)
Blue colour – Blue cherry and Jamun
Red beets - Pink to red.
Red onion skins - Pale purple to red.
Spinach - Green.
Purple grape juice = Lavender. Preservatives – Benzoic acid, sorbic acid and sulphur dioxide

26. End Point The end point can be determined by carrying out a jelmeter test. Generally, fruits which are fairly rich in pectin, the weight of the finished jam is one and a half times (11/2 times) the weight of sugar used. Jam containing 68.5 percent of soluble solids boils at 105°C at sea level. It should yield a definite quantity of the finished jam.

27. Use a refractometer This is the most accurate method. Take a small portion of jam from the pan. Let it cool to 20°C. Place one or two drops of the jam onto the prism and carefully close the prism. Hold the refractometer near a source of light and look through the end piece. Read the corresponding number on the scale, which is the percentage of sugar in the sample. Open the prism and remove the sample with a piece of tissue paper or wet cotton wool.

28. Use a sugar thermometer This method is slightly less accurate, but is very useful at the small-scale. A solution of 68% sugar boils at 105°C at sea level. When the boiling jam reaches this temperature, it is at its end point. Then remove the pan from the heat and dip the thermometer into hot water and then into the jam. If the thermometer reads 104-105°C, the jam is ready. If it is lower than this, return to the heat and continue to boil.

29. Drop test This is the cheapest option, but is the least accurate of the methods. It is good enough for use at the home level. Remove the pan from the heat. Dip a clean wooden spoon into the jam and hold it over the pan for 1 to 2 seconds. If the jam runs back freely, repeat the test every two minutes until the jam looks like a heavy syrup. When a small lump of jam forms on the back of the spoon and breaks away from the rest, the setting point has been reached.

30. Alternatively, you can drop the jam into a glass of cold water: Take a smalldrop of the boiled jam on a spoon. Cool it slightly and drop into a glass of cold water. If the drop falls in a single piece until it reaches the bottom of the glass the end point has been reached.

31. Use the skin wrinkle test Dip a clean wooden spoon into the jam and drip a small amount of jam onto the cold plate surface. Let it cool and then push the lump of jam with your finger. If the surface of the lump of jam wrinkles when you push it, it is cooked.

32. Sheet test/Spoon test A spoon of jam is dropped from a distance on to a plate and
if it falls down as a sheet – jam is do ne

33. Filling and packaging The jam is packed in sterilized glass jars. Glass Jars are thoroughly washed with hot water and filled with hot jam It should be noticed that unless the jars are stored in a fairly cool place, moisture will evaporate from the jam resulting in shrinkage of the jam. If jam is prepared from fresh, unsulphited fruit pulp then it is advisable to add about 40ppm of sulphur dioxide in the form of potassium meta-bi-sulphite to the jam, which is permitted by law.

34. A layer of molten paraffin wax can be put on the top surface of the cooled jam in the glass jar, which on cooling sets. This acts as a safeguard against any possible moulding on the surface of the jam. Jam is sometimes packaged in plastic containers, but this reduces its keeping quality considerably, and makes it proneto rapid spoilage. For the optimum storagetime, jams should be stored in a cool dry place, away from direct sunlight.

35. Jams is made according to the correct recipe will have a longshelf life. Jam stored in glass jars will have a longer storage life (up to 12 months) than those packed in plastic bottles (up to 4 months).

36. Problems in jam production I. Crystallization
II. Sticky or gummy jam III. Premature setting
IV. Surface graining and shrinkage V. Microbial spoilage

37. Precautions It should be avoided by diabetic and obese patients.
Due to the high content in sugar, it may cause tooth decay and lead to weight gain.