Common frozen vegetable production technical points

Vegetables are an indispensable and important food in people's lives. They are rich in VC, carotene, minerals and Other nutrients. Seasonal harvesting of vegetables is very strong and has a certain regional nature, which has caused difficulties in providing balanced supply throughout the year. In addition, vegetables contain a lot of water, and its chemical composition is also a good substrate for the development of microorganisms. Therefore, if it is stored at room temperature for a long time, it will cause the quality of the vegetables to decline or even deteriorate. Therefore, it is very important to preserve vegetables using low temperature, especially quick freezing.
There are many types of vegetables that are suitable for quick-freeze processing. Fruits and vegetables (the edible part is the fruit of the dish and young seeds) are: green beans, kidney beans, peas, tender beans, eggplant, tomatoes, green peppers, peppers, cucumbers, zucchini, gourd, Pumpkins, etc.; leafy vegetables (edible parts are fresh leaves and fresh petiole) are: spinach, celery, leeks, garlic, cabbage, rape, parsley, etc.; stem vegetables (edible parts are fresh stems and metamorphosed stems) There are: potatoes, asparagus, lettuce, taro, winter bamboo shoots, citrons, etc.; root vegetables (the edible part is the root) are: carrots, yams, etc.; cauliflower (the edible part is the flower's floral organ) with cauliflower, etc.; Species (the edible part is the fruit body of avirulent fungi) are: Fresh mushrooms such as mushrooms, mushrooms and so on.

1 Green beans

1.1 Pre-frozen treatment Green beans used for quick-freezing should be fresh, bright and green in color, uniform in shape, long and thin, free of spots, free from pests and diseases, and free from other contamination. All diseases, insects, abrasions, and deformities are removed. Those with no side tendons should be cut off at both ends. Types with side ribs should have side ribs removed and ends cut. The green beans are then washed 3 to 4 times in clean water.
1.2 Blanching and cooling The blanching is performed in hot water of 93-100°C for 1.5-2 minutes, so that the green beans become green and do not show a patchy shape. Blanching time and degree of blanching should be strictly controlled. When blanching is hot, it must be constantly stirred so that the blanching can be even. Blanching tool to use stainless steel mesh woven basket is appropriate.
The blanched raw material is first cooled with tap water or groundwater that meets the hygienic requirements, and then is placed in a cooling bath having a cold water temperature of 5° C. or less to cool the raw material to below 10° C., and then the water on the surface of the raw material is drained.
1.3 Frozen and refrigerated products are frozen in a quick-freezing device at a temperature of -30°C or less for 10 minutes, and packed in 0.25kg, 0.5kg, 1.5kg, 10kg or 20kg packages. Carton packaging, 20kg per carton. The temperature of the frozen storehouse is -18°C. The goods are stratified and stacked to prevent extrusion.

2 peas

2.1 pre-treatment of fresh peas to peel hoeing, artificial hoeing per person per hour can be processed 24kg; a larger amount of production should be used mechanical peeling, peeling per hour 2000kg. After pods pods should be divided into 7 ~ 8mm, 9 ~ 10mm , 11mm or more of various specifications, according to sales requirements of processing. Mechanical stripping should try to avoid mechanical damage.
2.2 Boiled and cooled beans are loaded into the basket and blanched in hot water at 100°C for 1 to 1.5 minutes. The length of blanching time should be determined by the size and maturity of the peas. The blanched raw material was cooled to below 10[deg.] C. and then the water on its surface was drained.
2.3 Frozen and refrigerated peas that have been processed and treated as described above are fed into a freezer unit and frozen by a Bucket Elevator , a vibratory feeder, and a conveyor belt. If the material is suspended in the fluidized bed to suspend the monomer, the freezing temperature is -30 °C, the freezing time is 7 ~ 10min.
According to a variety of specifications for packaging, plastic bags or boxes sealed tightly. Refrigerated in a low-temperature freezer at -18°C. Avoid crushing when stacking.

3 Kidney Beans

Raw materials should be fresh, bright green color, no pests, no spots, no deformities, cleaning 2 to 3 times. In the boiling water at 100 °C blanching 1.5 ~ 2min (blanching hot water temperature must not be less than 93 °C), remove and put in a clear water tank to cool, and then placed in a cooling pool cooled to below 10 °C. Avoid excessive loss of soluble material during blanching, cut it into several sections after cooling, and then freeze, pack, and refrigerate. The frozen kidney beans do not need to be divided and should be packaged, frozen, and then refrigerated.

4 tender beans

Select the appropriate degree of maturity of green beans as raw materials, stripping, immersed in 2% of salt water for 20 ~ 30min, to prevent discoloration. Remove from the salt water and wash in clean water. After blanching at 100°C in a 1.5% magnesium acetate solution for 30 seconds, it is slowly cooled in clean water at 10 to 20°C after being picked up, and then cooled to below 10°C in cold water at 5°C or lower, and drained and frozen. , packaging and refrigeration methods are the same as those for green peas.

5 Soybeans

After the soybeans are picked, they should be transported to the processing site within the shortest possible time. If the soybean meal is too long, it will turn yellow. Wash with a broom, blanched in hot water over 93°C for 3 to 5 minutes, quickly cool to below 10°C after removing. Centrifugal mechanical vibrating drainer was used to remove the surface moisture, followed by quick freezing of the monomers and refrigeration after small packages.

6 Eggplant

6.1 Pretreatment Select raw materials with suitable maturity, freshness, no pests, no damage, no microorganisms or pesticides, and select one by one to eliminate rejects.
After careful selection of raw materials for steaming, they should be washed and steamed. When used for frying, it should be peeled off. Artificial peeling should be thin, the loss is small, and the production rate is high. Generally cut into pieces, strips or sheets, which shape to take the cooking method prevail, for burning eggplant can be processed into a block or strip; for fried eggplant can be processed into a sheet and so on.
To prevent discoloration, paste immediately. After the slicing, the eggplant block is put into the wet starch and the paste is hung. It is generally believed that hanging paste is better than not hanging paste. Hanging paste is not only fuel-efficient, but also beautiful in shape; the eggplant block after hanging paste is immediately put into a boiling pan and fried, and it is generally suitable for frying golden brown. Lard, soybean oil and other vegetable oils can be used for frying eggplant. Experience has shown that the product is best when the lard is large and the soybean oil is low; fried eggplant should be placed in a stainless steel net to drain residual oil.
6.2 Cool and quick-frozen steamed or fried eggplant must be pre-cooled before freezing. Air cooling is generally used for cooling, but it must be ensured that there is no dust or other pollution.
For frying eggplant: can be directly fed into the fluidized bed freezing device below -30°C to freeze it, or it can be frozen in the tray on the tray of the tunnel car. Steamed eggplant: After cooling, it is quantitatively packed in plastic bags, placed on a trolley tray, and pushed into frozen tunnels below -30°C to freeze. After freezing, quantitative packaging or packaging plus storage at -18 °C after the warehouse refrigerated.

7 Tomatoes

Method one: Select mature and suitable fruits as raw materials, and eliminate pests, cracks, deformities or immature. After soaking for about 20 minutes with a 0.5% to 1.0% dietary calcium chloride solution, the surface water was drained and frozen in a freezing tunnel below -30°C. With this method, the freezing speed should not be too fast, otherwise brittle cracks will occur and affect the quality.
Method 2: Pre-freeze processing is the same as method one. After freezing at -30°C for 10 min, immediately place in water of 30-35°C to make the tomato skin crack, peel it manually, put it into plastic bag quantitatively, and then freeze below -30°C to freeze the center temperature to storage. Temperature -18°C.

8 green pepper

8.1 Pretreatment Select fresh sweet pepper (bell pepper) as raw material. Sweet green pepper should have a large flesh thickness, small placenta, bright color (green) without pests, hot spots, not bad. After picking, it should be processed as soon as possible, generally within 24 hours. After the raw materials enter the factory, they must be rigorously selected and then washed 2 to 3 times. According to consumption requirements can be processed into three kinds of specifications: cut: the green pepper will be cut into two slices longitudinally, to pedicle, cover, seed; cut: cut into two pieces after the net pedicle, cover, seed, and then cut into 10 ~ 15mm3 squares; shreds: cut into thin strips of a certain width. The cut green peppers were rinsed with fresh water and the floating seeds were washed.
8.2 Blanching, cooling and draining are performed in hot water at 100°C for 2 minutes. The blanching process may also be performed without freezing. But it must be cooled and drained.
8.3 Frozen, packaged, frozen raw materials after freezing 10min (freezing temperature -35 °C), quantitative packaging, refrigeration.

9 hot peppers

The green or red fresh pepper is used as a raw material, and the pepper must be bright, flesh-thick, spicy, free of pests, and spots. Wash 2 or 3 times, remove the entire stem after cooling and draining.

10 cucumbers

Quick-frozen cucumber is a popular frozen dish. The raw material requirements are fresh, there are less meat and more seeds, and autumn cucumber is the best. The best day of picking the day of processing, storage time does not exceed 24h. After the raw materials into the plant should be cleaned, immersed in a concentration of 5 ~ 10g / L of calcium chloride solution for about 20min, and then washed with water. According to cooking habits slice or dice, can be divided by hand, can also be used mechanically, manual cutting is not suitable for mass production. Advanced cutting machines should be used when using mechanical cutting to reduce juice loss. Can not use squeeze slicer, because this device will squeeze the juice inside the fruit and vegetable tissue, not only increases the loss of juice, but also due to too much juice on the surface of the bar, causing freezing when it becomes a defect, affecting the quality of frozen goods. In order to prevent the product from sticking and freezing during processing, it is most suitable to use a vibrating fluidized quick-freezing device for freezing processing. Freeze after the quantitative packaging, refrigerated at -18 °C warehouse. In the refrigerating, transportation, and sales links, care should be taken to prevent it from being squeezed.

11 Zucchini

Select suitable raw materials for ripening, peel, cut in half, scrape the pods and seeds, immerse them in an aqueous solution of calcium chloride with a concentration of 5 to 10 g/L for 20 minutes, remove them, wash them with clean water, and process as needed. In a piece or block, frozen at -30 °C in low temperature 10min, then quantitative packaging, refrigeration.

12 pumpkins

There are two kinds of frozen pumpkin and frozen pumpkin sauce.
12.1 Frozen Pumpkin Patch Peel the fresh pumpkin and cut it in half. Scrap the seeds and seeds. Wash and cut into squares of about 35mm3. Boil in hot water at 100°C for 5-6 minutes, then cool to below 10°C. After draining, freeze in a freezer and repack.
12.2 Frozen pumpkin sauce Peel the fresh pumpkin and cut it in half. Scrape the seeds and seeds. Cut them into strips and steam them. Manually mash or churn them into a sauce with a blender. Cool quickly to below 10°C in the packaging. And then quickly freeze.

13 Sweet Corn (Green Corn)

The sweet corn with appropriate maturity can be yellowish-white. Corn kernels should be plump and tidy, removing old raw materials. Due to the rapid progress of ripening after picking, freeze processing should be completed in as short a time as possible. Frozen corn can be frozen with a bar, and can also be frozen into grains. It is generally frozen in the country. The process is as follows: removing the skin, picking the net, blanching in hot water at 100° C. for 3 to 4 minutes, and rapidly cooling to below 10° C. after taking it out. It is frozen in a freezing device below -30°C for 10 to 20 minutes, frozen and packaged in plastic bags.
Another method is not blanching, remove the green corn dumplings, leave 1 or 2 layers of skin, freeze directly, and refrigerate after packing. The effect is also very good.

14 spinach

Choose leafy round leaf species. Raw materials are fresh, green, no yellow leaves, no pests, and the length is about 150-300mm. The interval between harvesting and freezing should be as short as possible. The storage time should not exceed 24h. Leaves, remove roots; wash each plant with spinach.
The roots and leaves of spinach have different tenderness and moisture content. Therefore, when blanching is performed, the time for blanching the roots should be longer and the leaves should be shorter. The specific method of operation is as follows: The root of the washed spinach is placed vertically downwards in the basket, and when the hot water is blanched, the root is first immersed in hot water for 30 seconds, then immersed in hot water for 1 minute. In order to keep the spinach thick After the blanching, it should be quickly cooled to below 10°C. After cooling, the spinach should be drained one by one. Each bundle of 500g is packed in a plastic bag, sealed on a sealing machine, and then frozen at a low temperature of -30°C for 20 minutes. The frozen spinach is brittle, easily broken, and should be light when packaged. Take light, usually a box of 20 bags.

15 Celery

Raw materials require fresh petiole, no yellow leaves, no pests and diseases, and bright green, more than 300mm long. When selecting the first plant, select all the leaves and remove the roots. After washing, cut into pieces that are one inch long and blanched in hot water at 100°C for 1.5 to 2 minutes, followed by rapid cooling to below 10°C. After draining, it is sent to the freezing device (under -30°C) and frozen for 10 minutes. Finally, it is packaged and refrigerated.

16 leek

Leek can be processed into frozen leeks filling. Raw materials require fresh, yellow leaves, no pests and diseases. During the initial processing, the plants should be selected one by one and the yellow leaves at the tips and the old leaves at the roots should be removed. Wash away the mud and dirt, cut into fine powder after draining, quantitatively pack and freeze at -30°C for 10-15min. Mix with edible oil, meat, salt and other auxiliary materials when eating.

17 parsley

Raw material requirements and initial processing are the same as those for leeks. After washing and draining, the whole plant is packed into a plastic bag, and the package quality is generally 100g, 250g, or 500g, and then it is sealed on the sealing machine and directly frozen.

18 Succulent

The processing season of garlic is generally after mid-May. The raw materials are fresh, no pests, no hot spots, and are not empty. The length is 350-500mm. The moss and old roots are cut after the roots are selected and washed 2 or 3 times. The blanching was performed in hot water at 100° C. for 1.5 to 2 minutes (blanketing was required after the sliced ​​garlic was cut into inch segments), and the blanching was followed by rapid cooling to below 10° C. The whole frozen garlic must be frozen after being packed neatly. The sliced ​​garlic is sent to a fluidized bed quick-freezing device and frozen for 10 minutes. Finally, it is quantitatively packaged and refrigerated.

19 potatoes

Not only can potatoes be made into convenience foods, but they can also be made into a variety of quick-frozen foods. Since potatoes can be stored for a long period of time, the development of domestic products is not sufficient at present. Actually, potato frozen products have a broad prospect.
Fast-frozen potatoes are fried, using a large, sleek, pest-free raw material, peeled, cut into the desired shape (such as tablets, blocks, diced, strips, etc.), fried in golden oil with soybean oil, drained, cooled , fast freezing, packaging, refrigeration. Refrigerated at up to -18°C for up to 12 months.
In addition, other raw materials can also be added to make convenience foods such as potato cakes, potato cakes, expanded potatoes, and scorpion potatoes.

20 Shantou

Shantou is prolific in the south, and its frozen products (quick-frozen oysters) are sold abroad in large quantities. The raw materials should be sorted by grade, cleaned and peeled according to grade, and immediately immersed in water to prevent oxidation browning. The blanching is performed in hot water at 100° C. for 5 to 10 minutes. The blanching time depends on the size. After blanching, it is cooled to below 10° C. and drained. It is frozen in the freezing device (below −30° C.), and is refrigerated after quantitative packaging. Due to the discoloration of iron ions in steel heads, it is strictly prohibited to use iron tools during processing. Different types of gimmicks should be selected and graded separately for quick freezing so as to save energy.

21 carrots

Carrot is a nutritious and easily processed vegetable. Raw materials require bright red, small yellow core section, no damage to the gloss. Processing should be selected one by one, cut off the inedible parts, cleaned 2 or 3 times, cut into various shapes as required, such as block, sheet, strip, broken diced, round patterns, long patterns, etc. The remaining edge material is generally processed into pieces. Products for export should be peeled according to the requirements of the merchant, and peeling machines can be used in mass production. The processed product is poured into the basket and blanched in hot water at 100°C for 1 to 3 minutes. The degree of blanching should be strictly controlled. If the blanching is too hot, the phenomenon of softening, discoloration, etc. will occur, affecting the product quality. After being blanched, it is chilled to less than 10°C. After being drained on a vibrating drainer, it is sent to a quick-freezing device for freezing for 10 minutes, and then refrigerated after quantitative packing.

22 Cauliflower

The edible part of cauliflower is the flower part of the dish. The raw materials require white, large flowers, and no pests and diseases. During initial processing, the outer leaves and petioles are cut off and then cut into pieces of appropriate size. Wash 2 or 3 times, blanching in hot water at 100°C for 1 to 2 minutes. Quickly cool to below 10°C after removing and drain, freeze and pack.
In order to prevent cauliflower discoloration, steam blanching is generally used instead of hot water blanching. Steam blanching usually takes 4 to 5 minutes; for example, hot water blanching to maintain the white color of cauliflower, 0.1% citric acid can be added in hot water.

23 Mushrooms

23.1 Pretreatment The mushroom used for quick freezing should be complete, white and elastic, free of mud roots, no pests, no mechanical damage, hollow and white heart. The stipe does not exceed 15mm, and the diameter of the mushroom is about 30mm. Wash 2 or 3 times, wash away dirt, dirt and so on. Boil for 3 to 5 minutes in hot water at 100°C. Control the water temperature strictly to prevent discoloration of the mushrooms. After blanching, quickly cool to below 10°C in a cold water bath.
23.2 The grading and freezing of frozen mushrooms are generally divided into large, medium and small grades. The diameter of the umbrella cover is 40mm or more, 30-40mm, or 30mm or less. Mushrooms of different sizes are separately frozen and quickly frozen using fluidized monomers, which is most suitable at -35°C. For different specifications of the packaging, the general bag is 250g, 500g or 1000g. Sealed bag should be excluded from the air, and finally pack cold.

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