The word ‘Jam’ is said to be derived from French word “J’aime” whereas some expert expressed opinion that it came from the Arabian word ‘Jamad’ means preserved fruit. Jam can be prepared by boiling the pulp of any fruit with sufficient amount of sugar and citric acid to a desired thick consistency, firm enough to hold fruit tissues in position. The finished jam should also contain 30 to 50 percent invert sugars or reducing sugars or glucose to avoid the crystals formation in the jam during storage. The cane sugar or non-reducing sugar or sucrose may crystallized if jam contains less than 30 percent invert sugar while jam becomes honey-like mass if more than 50 percent invert sugars are present due to crystallization of invert sugars into small crystals. The suitable per portion of pectin, sugar and acids develops the desirable pH of the mixture that gives good setting to the jam. The good setting may be obtained by cooking the mixture having around 3.3 pH. The mixture is boiled into pans preferably steam jacketed pan to get not less than 65 percent TSS and desired inversion of sugar. Sugar acts as preservative at 65 percent and above concentration. The mixture may be cooked into vacuum pan comparatively at lower temperature of 65 to 760C to prevent the vitamin C loss and undesirable colour change but flavour is lost due to prolonged boiling. The duration of boiling must be appropriate to prevent the undesirable over concentration of TSS, over inversion of sugar and hydrolysis of pectin.
Definition
Jam may be defined as a product prepared by cooking fruits pulp with sufficient quantity of sugar and citric acid to a reasonable thick consistency in order to hold the fruit tissues in a position. According to Codex Alimentarius Commission “Jam is the product prepared from whole fruit, pieces of fruit, fruit pulp or fruit puree; and with or without fruit juice or concentrated fruit juice as optional ingredient(s) and mixed with carbohydrate sweetener , with or without water; and processed to a suitable consistency.” According to FSSAI “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. It may be prepared from any of the suitable fruits, singly or in combination. It shall have the flavour of the original fruit(s) and shall be free from burnt or objectionable flavours and crystallization”.
Suitable fruits
Any fruit like Apple, Aonla, Mango, Papaya, Peach, Pear, Plum Sapota, Muskmelon, Watermelon, Strawberry, Raspberry, Cherry, Gooseberry, Apricot, Pineapple, Banana and even carrot root may be used for jam making but pulpy fruits are preferred for jam preparation. The fresh, frozen, cold stored fruits and preserved fruit pulp may be processed into jam. Although pectin is not essential in jam making but jam gets good setting due to pectin present in the fruits. Use of ripe fruits pulp makes jam rich in the flavour of fruits. The both mature fruits which are rich in pectin as well as ripe fruits which are rich in flavour should be used in the preparation of jam to ensure the good setting and flavour rich quality of jam whereas over ripe fruits should not be used for jam preparation. The fruits are thoroughly washed before converting them into pulp for jam making.
Food Safety and Standards Authority of India (FSSAI) Standard
Particulars | Specification |
Fruit content | not less than 45 percent |
T.S.S | not less than 65 percent |
Preservative (Maximum) | Benzoic Acid- 200 ppm or SO2 - 40 ppm 0r Sorbic Acid- 500 ppm |
Artificial Sweeteners or Polyols (Maximum) | Aspartame- 1000 ppm or Sorbitol- 30% |
Mould Count | Positive is not more than 40 per cent of the field examined, not more than 125 per 1/60 c.m.m. |
Recipes for some important fruits
Fruit | Pulp (Kg) | Sugar (kg) | Citric Acid (g) | Water (ml) |
Aonla | 1 | 0.75 | 1.0 | 200 |
Apple | 1 | 0.75 | 2.5 | 150 |
Pear | 1 | 0.75 | 2.0 | 125 |
Papaya | 1 | 0.50 | 2.0 | 100 |
Spota | 1 | 0.75 | 3.0 | 125 |
Mango | 1 | 0.75 | 2.0 | nil |
Guava | 1 | 0.75 | 2.0 | 100 |
Pear | 1 | 0.75 | 1.5 | 150 |
Strawberry | 1 | 0.75 | 2.0 | 100 |
Raspberry | 1 | 0.75 | 2.0 | 100 |
Preparation Technique
Selection of fruits
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Washing & peeling
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Pulp extraction
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Addition of sugar
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Cooking up to the end point
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Addition of colour if required
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Filling hot (90-920C) into sterilized jam bottles
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Waxing
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Capping and labeling
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Storage
Judging the end point
The end point indicates that jam is ready and cooking is not required further. The end point of the jam can be determined by following methods:
Weight
The weight decreases during boiling due evaporation of water when the weight remains 1.5 times of the weight of the sugar added then jam becomes ready to fill into containers.
Total soluble solids
The finished jam should contain not less than 68 percent T.S.S at 200C or 68.5 per cent at room temperature. The jam is considered to be ready for filling into jam bottles when total soluble solids reached to 68 percent.
Temperature
The 106°C temperature of the cooking jam at sea level indicates the end point but boiling point decreases with increase in altitude therefore end point temperature is kept more than 106°C according to altitude to get the desirable TSS of more than 68 percent.
Plate test
When the few drop of boiling mixture put into a plate with the help of spoon oozing out of water from the mixture indicates need of further cooking while no oozing of water means jam is reached to end point.
Problems in jam
Surface graining and shrinkage of jam
The problem occurs because of the loss of the moisture in excess from the jam through evaporation resulting in the formation of small granules on the surface of jam and also shrinkage of jam. The problem may be controlled by proper capping and storing the jam bottles at cool places.
Crystallization of jam
The cane sugar or sucrose or non-reducing sugar inverts during boiling of fruit pulp, sucrose and citric acids into glucose or reducing sugar or invert sugars. The finished jam should contain 30 to 50 percent invert sugar. The cane sugar may crystallize if jam contains less than 30 percent invert sugar whereas jam changes into honey-like mass when invert sugar content is more than 50 percent due to crystallization of glucose into small crystals. The glucose or corn syrup should be added to prohibit the crystallization of sugar.
Premature setting of jam
A good combination of pectin, sugar and acids gives proper setting of jam and to get the combination these ingredients are added in appropriate quantity. The premature setting of jam takes place if mixture contains less TSS and excess pectin. The premature setting may be avoided by added sugar as per pectin content of the mixture.
Spoilage by moulds
The moulds grow below the lid of the jam containers when sufficient relative humidity remains available. The moulds decomposed the jam and some time it becomes unfit for human consumption. The check the jam from mould spoilage the hot jam should be filled into sterilized bottles. The mouth should be waxed and sealed air light with sterilized lids. The jam bottles should be stored at cool & dry place. The Potassium metabisulphite to produce 40 ppm So2 may be added into jam to check the moulds growth.
Gummy and sticky jam
Jam becomes gummy and sticky when excess sugar is added into pulp for jam making. The proper quantity of the sugar should be added to avoid the problem. In case of excess quantity of sugar has been added the problem is corrected by adding pectin or citric acid or both during cooking.
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