Freshly picked asparagus 20 if exposed to air , the average loss of about vitamins C5O% per day. If stored at ambient O , the amount of the loss is significantly reduced. Broadly speaking , lower storage temperature 10 , the proliferation of microorganisms can be reduced by half.

Frozen fruits and vegetables , the main cryogenic grade polyethylene plastic film packaging. Packing in a vertical molding machine for filling an aggregate . Packaged form was shaped pillow . To reduce the activity plastic packaging box of frozen fruit , during the filling step of packaging often a certain amount of added sugar , and leafy vegetables prior to freezing the first pre- cooked .

Before packaging, pre-prepared and frozen fruits and vegetables weighing job is a relatively cumbersome process . For example, before packaging , have to fruits, vegetables, grading and inspection. These processes are often performed after the freezing . Take the belt vibration method can assist product separation and classification. In the inspection apparatus may be provided between the refrigerator or freezer with the weighing station . Conveyor speed and flow must be controlled to ensure accurate weighing and smoothly. Larger package (each 5Kg) weighing device can be arranged together in forming a filling a packaging production line. Some products ( such as peas and dried vegetables, etc. ) clamshell packaging according to the size of the volume of packaging . Young fruit vulnerable to damage , such as poison , black plastic packaging design poison , raspberry , etc. before freezing is plastic trays best to use polyethylene bags packaging.

Frozen fruits , fresh vegetables and different . Before freezing, fruits and vegetables are subject to past stems , peeled , pitted and peeled , such as processing , in order to reduce unnecessary waste of energy. Cut into small entities left , sheets, wire, or minced into the mud, and then frozen . In the process , we must pay attention to some issues, such as vegetables after harvest during the pretreatment interval length , often causing it to lose flavor ; . Produce if placed at a temperature of 30 24 hours, it ‘s boring points will be lost 1 / 2 ; after peas marinated placed under 25 6 hours, about the loss of its sugar l / 3. Spinach , beans, potatoes, mushrooms and , at higher ambient temperatures is placed , it will lose a large amount of glutamate and flavor . Thus , rapid and timely handling of such frozen foods. Was to reduce various losses above a minimum the only way to .

Bananas , peaches, apples and pears and other fruits , peeled and exposed to air , will soon become mortgage -colored catechol tannins . If taken and frozen nitrogen , substituted nitrogen, oxygen to mitigate the action of enzymes , and thus to prevent discoloration . Ascorbic acid is also added to prevent discoloration. Strawberry peeled exposed to air , will soon discoloration and dehydration, but the taste is very fresh.

Vegetables, precooked hot water or steam through the purpose of making some of the enzyme plastic box inactivation , for example , vegetable taste causing inactivation enzyme catalase . Pre-cooked vegetables can save the color . However , pre-cooked can cause loss of nutrients and vitamins vegetables should be avoided. Cooked fresh frozen vegetables more difficult .

IQF frozen fruits and vegetables requirements , otherwise , it will cause packaging design tissue freezing inside the cell , thereby undermining the internal structure of the product , causing weak and erosion. If freezing temperatures alternating uncertain and more will encourage the formation of ice crystals . Some fruits after freezing later, is still very sensitive to oxygen , oxidizes black. Changed its original flavor. Because at refrigerated temperatures , the effect of fruit and vegetable products and the enzyme reaction is still going on , but more slowly than at room temperature only. Generally , frozen after the still very sensitive to oxygen , oxidizes black, changing its original flavor. Although the freezing temperature , the effect of fruit and vegetable products and the enzyme reaction is still going on , but more slowly than at room temperature only. Generally, the temperature at which freezing or below -17.7 , fruit not seriously change occurred in a few months to a year or so . But once thawed, it ruined the speed is much faster than before freezing . After the fruits like plums , subjected to freezing and thawing , become very sour, when sugar consumption needs . Some fruits are leaking water , which was the dry, juice reduced. Most acidic fruits do not contribute to dangerous pathogens , such as Clostridium , but such fruit is very easy to fermentation and mildew.

Frozen fruit and vegetable packaging should primarily to prevent dehydration , while providing convenience to transportation , from physical and mechanical damage. Shading and oxygen barrier is not important unless the individual oxygen sensitive products. Most frozen fruits and vegetables packaging film or polyethylene plastic and composite materials , and some also uses polypropylene and ethylene / vinyl acetate film. Low cost of such films , transparency, water vapor transmission rate, low temperature brittleness can meet the requirements. These features than wax wrapping superior. Foreign polyethylene plastic bags of polyester (PET ) film with a good sauce made ??from the packaging mix vegetables ( such as mushrooms , beans , carrots, peppers and other vegetables prepared into several ) can be stored frozen , customers buy after the house directly to the bag to release the pot cooked, open clear plastic packaging the bag to remove the dishes eaten bags also belong to this type of cooking bag . Two bags a carton plastic packaging , a retail packaging of frozen vegetables.

Other packaging frozen fruits and vegetables are coated cellophane moisture , moisture ( plastic or coated with wax ) carton and foam polystyrene packaging box ( or boxes ) and so on .

Usually taken to reduce the storage temperature to control the emblem of biological reproductive capacity and proliferation rate . However, some tropical fruit not suitable for cold storage , are susceptible to frostbite , so fruits and vegetables should be the appropriate choice depending on the characteristics of the storage temperature . Table 3 lists 4 a suitable storage temperature of some fruits and vegetables , humidity and storage period .

Storage life of fruits and vegetables in addition to temperature and humidity have a direct effect on its metabolism ( respiration rate ) , the pair of outside mechanical damage , is also very important factors. For example, when picking handled with care to prevent vibration and shock during transportation , warehousing , and so when avoiding pressure . Experimental results show that lemon drop from the height of 46cm , which can speed up the breathing rate of 60% ; withstand the pressure 9.8N/cm2 after their breathing rate may accelerate doubled. Skin breakdown fruits, vegetables , and most likely lead to microbial invasion vac tray . Fruits, vegetables, high moisture content , stored in a low relative humidity environment tend to lose moisture , wilting occurs . Best stored at a relative humidity of 85 % to 90% range of places. While a suitable water vapor transmission rate should be used to protect the packaging material . Low water vapor transmission rate of the packaging material is easy to cause anaerobic conditions and mold breeding ; high moisture permeability of the packaging material and it is difficult to prevent moisture loss, should be based on product performance requirements , a suitable choice of packaging material , respectively .