Packaging of the hottest fruits and vegetables

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Packaging of fruits and vegetables

pretreatment of fruits and vegetables before packaging

pretreatment before packaging refers to that the fruit is soaked in chemical solution before packaging, so as to eliminate the mold and bacteria on the surface of the fruit, so as to reduce the harm of microbial invasion during the circulation of the fruit. In addition, it also includes the sterilization of packaging materials, packaging liners and packaging containers

apples are most prone to brown spot during storage. The main prevention method is to wrap it with oil soaked paper. The paper is impregnated with mineral oil or paraffin oil, and the amount of oil impregnated is 15% - 17% of the weight of the paper. The effect of wrapping pear fruits with this kind of oilpaper is also very significant. In addition to oil paper, it can also be impregnated with copper carbonate solution. The effect of soaking oil is mainly to prevent brown spot, while the effect of soaking copper carbonate can control the destruction of gray grape spores

for citrus fruits, biphenyl is generally used as an effective fungicide. Fruits can be directly immersed in biphenyl solution for about 2 minutes, or biphenyl solution can be used to treat packaging paper and padding materials. Although biphenyl also has some peculiar smell with functions such as limit protection and overload protection, this smell will naturally disappear when the fruit is exposed to the air. A fiberboard box, with a volume of about 30 liters, if the top and bottom of the box are lined with a gasket. The total amount of biphenyl absorbed by these two gaskets is about 4.7G. Corrugated boxes are also widely used. Fruits are put into perforated plastic bags and then placed in corrugated boxes with upper and lower liners. These two linings have been impregnated with biphenyl solution, and their efficacy is longer. After taking out the gasket, the efficacy can still be maintained for more than a week. However, in order to control the corruption of fresh fruits, it is necessary to use linings that have been soaked in liquid medicine. As a fungicide for citrus fruits, in addition to biphenyl, sodium phosphate phenol can also be used. According to the regulations of the U.S. Food and Drug Administration (FDA), the residue of fungicide on fruits is: biphenyl shall not exceed 110ppm. Sodium phosphite shall not exceed 10ppm. At the same time, it is stipulated that all packages that use sterilizing agents must be marked with the words "sodium phosphate phenol as sterilizing agent" on the package

sodium phosphate phenol can be mixed with hexamine (trade name: utopine), with sodium phosphate phenol 2% and hexamine 1%. The method of use is to prepare the sterilizing agent into an aqueous solution, and then directly immerse the fruit or carefully brush it. The method of preparing the solution is as follows:

① put caustic soda (industrial pure) 1:14kg, sodium phosphate phenol 11.4okg, hexamine 5.70kg. Add water to a total of 683kg, and stir to dissolve it evenly to form a solution

② prepare 0.77kg caustic soda (industrial pure), 22.75kg sodium phosphate hexamine concentrate and 432.25kg water into a solution

when the fruit is soaked, the temperature of the solution should be maintained at about 35 ℃. After soaking for 2 minutes, rinse with clean water. The concentration of the solution was measured by Bailey hydrometer and kept at about 2.7 ℃. The pH value of the solution should be kept between 11.5 and 12.2

sodium phosphine, hexamine and biphenyl can be mixed, but they should meet the requirements of relevant regulations. For fruits that are transported for a long distance and ready to be refrigerated or packed in plastic bags, better protective effects can be obtained after the above solution treatment

the packaging paper is impregnated with biphenyl solution, and the biphenyl content in the paper is 1.75%; The impregnation content of the liner in the packing box is about 17%. The maximum content of biphenyl in wrapping paper is about 6.2mg/100cm2

sales packaging of fruits and vegetables

[1) plastic film packaging

fruits and vegetables are packaged with various plastic films. The main problems that should be discussed are the influence of film permeability and water vapor transmission on product quality. The research shows that when the concentration of oxygen in the packaging system is less than 3%, the normal respiration of fresh products will be destroyed and gradually turn into anaerobic fermentation reaction. The lower limit of oxygen concentration in the system shall not be less than 5%. The oxygen permeability of various plastic films currently used is not enough to meet the needs of fresh product breathing. Experiments show that if two small holes with a diameter of 3.8mm are made on a plastic bag, it is enough to prevent the anaerobic fermentation reaction of fresh products in the bag.

general plastic films can be made into sheets, rolls, plastic bags and plastic covers, as well as shrinkage and non shrinkage. Before the early 1970s, cellophane was the main non shrink film used for packaging fruits and vegetables. After that, various types of cellophane were gradually replaced by plasticized polyvinyl chloride film. Cellophane and plastic film can be coated with nitrocellulose or polyvinylidene chloride on one or both sides to improve moisture resistance, heat sealing and water resistance. Cellophane itself is a semi oxygen permeable film, and several holes must be punched to increase its oxygen permeability to meet the needs of product respiration. The mechanized punching can adopt the rolling punching machine, and the stacked films will be punched with holes of the same specification and size through the punching machine. If it is a covering film, there is no need to punch holes

PVC stretched film has excellent transparency and gloss, does not generate fog, and is not easy to crack when being killed. It is an ideal material for wrapping fruits and vegetables. At present, it is also widely used.

polyethylene film is often non heat shrinkable and low-density, and its heat sealing property is good. Although the transparency is not as good as cellophane, it can be improved. Polyethylene film is often made into plastic bags to pack hard fruits and root vegetables such as oranges, potatoes, onions and carrots. If fruits and vegetables with high breathing rate are packed, the plastic bag needs to be perforated to increase its oxygen supply. Polyethylene plastic cover is often used to pack celery, and small plastic is used to pack nest head. This kind of package is easy to heat seal, strong and has high tear strength. Acetate film has high transparency, dazzling luster and attractive packaging. Its air permeability (O2 and CO2) is high, which is unnecessary for product packaging with low breathing rate. It is often used to wrap lettuce and tomatoes in cartons. Sometimes it is also used as a transparent film for window cartons. 7d

the transparency and permeability of polystyrene film are similar to that of cellulose acetate film, but they are brittle. It is often used to wrap lettuce and tomatoes, and can also be made into heat shrinkable film for shrinkable packaging

perforated polypropylene film is used for body fitting wrapping and packaging cabbage, lettuce, Laihua and other vegetables

other heat shrinkable films include radiation crosslinked polyethylene, polyvinyl chloride, polyvinylidene chloride and polypropylene, which are used for optional wrapping of heat shrinkable "calibration" items of fruits and vegetables. If they are packed in shrink bags, they need to be perforated to varying degrees

(2) shallow dish packaging

if the food is contained in the form of tray, covered with plastic film, or the tray and food are packed into plastic substitutes or carton cases, the shore a hardness value is obtained It belongs to shallow dish packaging. The materials of pallets include molded products of pulp or paperboard, thermoforming of plastic sheets, foam shallow trays, composite materials and aluminum foil. Different materials adapt to different packaging requirements. For example, a certain kind of shallow dish can hold 4 painted fruits, such as tomatoes or oranges; Another kind of shallow dish can hold two ears of corn; Another kind of shallow dish can hold six ears of corn or five or six baked sweet potatoes, etc. The main function of some containers is to protect products from mechanical damage; The function of some containers is to improve the sales appearance of products. In a word, the packaging containers with appropriate materials must be selected according to the requirements of product packaging

(3) boxes, baskets and box packaging

all wooden cases, pulp molded products, plastic baskets, windowed cartons, flap cartons and various cup containers belong to this category. Some are suitable for the packaging of berries, and some are suitable for the packaging of hard fruits. Windowed cartons are convenient for decoration and product description. Cartons are superior to wooden cases. The application of plastic turnover boxes is also increasingly common

(4) bag packaging

this type of packaging container includes all kinds of bags (except plastic bags), as well as kraft paper bags, double-layer paper, windowed paper bags, fiber bags, plastic bags, paper bags with holes and plastic bags. Bags and bags with eyelets have always been used to pack products such as potatoes, onions and oranges. High density polyhexene plastic film bags with holes are most suitable for packaging grapes, oranges and other fruits in orchards

source: Food Forum

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