Detailed Explanation of the Processing Technology and Production Method of Jujube Puree
Jujubes are sweet and delicious, and rich in nutrients. According to measurements, every 100 grams of fresh jujubes contains 380 mg of vitamin C, 0.06 mg of vitamin B1, and 0.04 mg of vitamin B2, with calcium and phosphorus at 41 mg and 23 mg respectively. They also contain relatively large amounts of sugar, protein, and so on, making them a highly prized delicacy among fruits. Traditional Chinese medicine holds that red jujubes warm the middle and nourish, making them an excellent health tonic for the elderly and children.
Jujube puree processed from red jujubes is sweet and delicious, rich in nutrients, and is a popular table food among consumers. The processing technology for jujube puree is described below:
I. Process Flow
Raw materials -> raw material selection -> soaking -> washing -> softening -> pulping -> rubbing the pulp -> concentration -> filling into cans -> sealing -> sterilization -> cooling -> finished product
II. Key Operating Points
1. Raw materials: Select dried red jujubes that are large and thick-fleshed, and remove broken, rotten, and insect-damaged jujubes. Remove impurities such as stems and calyxes.
2. Soaking: Soak in clean water for 24 hours, then rinse thoroughly under running water, and pick out rotten and insect-damaged fruits.
3. Softening: Place 50 kg of jujubes in a stainless steel double-layer pot, add 25 kg of water, and simmer for 2 hours, stirring 1 to 2 times during the process, until the jujubes are soft and mushy.
4. Pulping and rubbing the pulp: Use a pulper with a pore diameter of 0.2 mm to pulp, removing the jujube pits and skins, then use a nylon sieve to rub the jujube pulp by hand (wearing latex gloves) into jujube paste, removing any remaining jujube skin.
5. Concentration: Carry out in a stainless steel double-layer pot. The formula is as follows: 20 kg of jujube paste, 37.5 kg of white granulated sugar, 3 kg of starch, 150 g of agar, 3 kg of cooked lard, and 2.3 kg of candied osmanthus or candied rose. Prepare the white granulated sugar into a syrup with a concentration of 75%, boil and filter; dissolve the agar in 5 kg of water, filter, and set aside; boil 1 kg of spice with 3 kg of water, filter, and set aside. Add the syrup to the jujube paste, heat and concentrate under a pressure of 0.2 MPa, taking care to stir frequently. When the soluble solids of the jam reach 50%, add the agar; continue concentrating until 55%, then add the cooked lard and spice water, and concentrate for another 10 minutes, stirring evenly, and it is ready to be removed from the pot. If vacuum concentration is used, first start the vacuum centrifugal pump to create a vacuum in the vacuum concentration pot. When the vacuum degree reaches 0.055 MPa, open the feed valve to draw in the jujube paste and syrup, with the vacuum degree at 0.086 to 0.096 MPa and the temperature at 0 to 70°C. During concentration, if boiling is violent and there is excessive foam, the air valve can be opened to let in an appropriate amount of air to suppress the rising foam. During concentration, the material must be kept above the heating surface to prevent scorching. When concentration is near the endpoint, add the spice, cooked lard, and agar, and continue concentrating to the specified concentration. Turn off the vacuum pump, heat the jam to 90 to 95°C while stirring, then quickly close the air inlet valve and remove from the pot.
6. Filling: Use 776-type tinplate cans or four-twist jam jars. Keep the jam temperature above 80°C during filling, do not let the jam contaminate the rim of the can, and wipe the can (jar) rim clean with a clean gauze before capping.
7. Sealing and sterilization: After the jam is filled into cans, it must be sealed immediately, and the sealing quality must be checked at the same time. If the seal is found to be not tight or the vacuum degree is low, open the can and reseal it. Jam sterilization generally uses steam sterilization: raise the temperature for 5 minutes, sterilize at 100°C for 20 minutes, spray with warm water to cool for 5 minutes, then spray with cold water to cool.
III. Finished Product Quality Indicators
Color: brownish yellow to brownish brown. Taste and odor: has the taste and odor that canned jujube pulp or jujube pulp with added natural spices should have, with no off-flavors. Texture and form: no jujube pits, in a gummy or dry sandy state, does not flow or spread, no sugar crystals, and a small amount of jujube skin fragments is allowed. Impurities: not allowed.
(1) Net weight: 340 g, with a tolerance of ±3% per can, but the average of each batch must not be lower than the net weight. (2) Total sugar content: not less than 50% (calculated as invert sugar). (3) Soluble solids: not less than 55% (by refractometer). (4) Heavy metal content: in each kilogram of product, tin content not exceeding 200 mg, copper not exceeding 5 mg, and lead not exceeding 1 mg.
No pathogenic bacteria and no signs of spoilage caused by microbial action.
IV. Precautions
1. Jujube puree has a low acid content, so the invert sugar content should be strictly controlled to prevent sugar crystallization.
2. If vacuum sealing is used for jam cans, the vacuum degree should not be too high, and should not exceed 0.02 MPa, to prevent the jam from being drawn into the machine, which would affect the can filling amount and contaminate the machine.