To make fruit jam at home need the following steps: Fruit sorting, washing, precooking, pulping, concentration, filling and sterilization. First, select qualified raw materials and clean them up. Then, precook them in hot water until they get soft, and pulp them into fruit puree. Next, heat and concentrate to raise the sugar content. Finally, fill fruit jam into cans before they get cooled, and sterilize them in boiling water or special pot.
Raw materials processing
Fruits for making jams should have high maturity, high fruit pectin and tartaric acid content. You should first pick out the qualified fruits and get rid of the rotten ones. For mass production, a fruit sorting machine would be helpful.
Then you have to remove their cores, peels, pedicles and calyx, and clean them by hands or with a fruit washing machine. Besides, you need to immerse them into citric acid or salt solution to preserve the color of fruits.
Fruit precooking and softening
If you want to make fruit pulp at home, a steam layered pot is enough. Cut the fruit pulp into pieces and put them into the pot, then add water of 2 times the volume of fruits. For different fruits and maturities, the cooking time is varied but less than 10 minutes.
For mass production, a spiral continuous precooking machine is helpful. When raw materials falls on the cylindrical screen, a screw propeller put it downward and immerse the fruits into hot water, where they are heated to soften. Then they are discharged through the outlet.
Fruit pulping process
When fruit become soft and easy to puree, you can use a fruit pulping machine to make them into puree and separate the pomace. Through the 0.8mm screener in fruit pulping machine, fruit purees are sieved into uniform size and pure color, without any particles or impurities.
Adding sugar and concentration
The sugar content of fruit puree should be more than 65%, solid content over 68%, citric acid 0.7%. So adding sugar, heating and concentration is necessary for making fruit jam at home.
Concentration devices can be classified into normal pressure and vacuum 2 types. A steam jacket kettle works under normal pressure. You need to set the steam pressure between 1-1.5 kg/cm2. Keep stirring to prevent coking. When the sugar content is up to 65%, add dissolved jam stabilizer, and continue to stir and heat. At last, add preservatives and acid and mix them well.
Fruit puree filling and sterilization
Canning must be carried out right after the fruit puree comes out of the kettle. The canned fruit puree temperature should be no less than 85℃. After sealing, put them into boiling water or steam for about 20min to eliminate bacteria, then cool them gradually and wipe them to dry.
For mass production, double piston constant loading machine is a specialized device for canning. It can realize precise quantification, adjustable volume and good filling effect. For sterilization, high pressure sterilization pot is commonly used for canned and bottled products.
To identify the quality of fruit jam, spreadability is an important indicator. When you scoop it up with a knife, it should be hard to flow down from the knife. And you can spread it up evenly on breads or other food. Generally, even concentrated fruit puree appears fluid, you need to add some fruit jam stabilizer when making fruit jam.