Analysis of the hottest freeze-dried food packagin

2022-10-20
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Analysis of freeze-dried food packaging technology

freeze-dried food has become another new type of processed food popular all over the world. Before eating, freeze-dried food can be processed or eaten as long as its original color, aroma and taste are restored after being hydrated. Freeze dried food is easy to rehydrate, and retains the color, aroma and taste of fresh food to the greatest extent, as well as the original nutritional and physiological active ingredients of food to the greatest extent. Therefore, freeze-dried food has become a high-quality instant food, which makes many functional food or high-end food raw materials use freeze-dried food raw materials, and also makes freeze-dried food become high value-added food or raw materials. In some developed countries abroad, freeze-dried food has become an important main food for athletes, field troops, astronauts and other special professionals. It also plays an important role in civil food. For example, 50% of Japan's fast-food is freeze-dried food. In the international market, the price of freeze-dried food is more than four times higher than that of traditional dehydrated food. China's freeze-dried food has just started, but it is predicted that freeze-dried food will become a rising star in China's food industry in the future

freeze-dried food refers to dehydrated food after freeze-drying treatment. It is a new type of food that carries out special treatment on fresh food to achieve fresh preservation and quality assurance. In terms of quality, it is superior to traditional hot air drying, spray drying, vacuum drying and other dehydrated food; From the perspective of storage and transportation, it is far better than quick-frozen food and canned food

packaging characteristics of freeze-dried food

1. Quality characteristics of freeze-dried food

the biggest quality characteristics of freeze-dried food is to maximize the drainage of water from foods with high moisture content through freeze-drying, including freeze sublimation drying and vacuum freeze-drying. Its quality characteristics are as follows

(1) the shrinkage rate of freeze-dried food is far lower than that of other dried foods, which can maintain the shape of fresh food

(2) freeze dried food has no surface hardening phenomenon, and during rehydration, water can quickly penetrate into the interior of freeze-dried food, so it has excellent rehydration performance

(3) during the processing of freeze-dried food, the common phenomenon of heat sensitive components being destroyed and easily oxidized components being oxidized in food processing is avoided. Therefore, the retention rate of nutritional components and physiological active components of freeze-dried food is the highest

(4) freeze dried food is processed at low temperature, and there will be no discoloration caused by pigment decomposition, browning caused by enzymes and amino acids. When eating rehydration, it can achieve the bright effect without adding pigments

(5) when freeze-dried food is processed, the volatility of aromatic components is low, and the concentration of aromatic components increases relatively after drying, and the aroma is thicker

the above quality characteristics determine the packaging characteristics of freeze-dried food

2. Packaging characteristics of freeze-dried food

(1) freeze-dried food is completely dehydrated without adding any preservatives. It can be stored safely and for a long time with proper packaging

(2) the structure of freeze-dried food is porous sponge. If it is improperly packed, it is easy to absorb moisture and deliquesce once exposed to the air

(3) the specific surface area of freeze-dried food is large, which is easy to contact the oxygen in the air with the inside of the food. Over time, the fat in it will be oxidized and rancid, which needs to be controlled by packaging technology

(4) the relative density of freeze-dried food is small and its volume is relatively large. In addition, it has a porous vegetable pine structure, which is fragile and inconvenient for transportation (it needs to be transported after packaging)

the above quality characteristics and packaging characteristics are the research team led by Ivan vallasock has prepared a 2-inch square single atom thickness carbon composite, which must be considered in our design and selection of packaging methods and technologies

frozen food packaging techniques

the main purpose of freeze-dried food packaging is to solve the problems of moisture absorption, oxidation and deterioration

1. moisture proof packaging techniques

freeze dried food is easy to absorb moisture and become damp, that is, it is easy to absorb moisture in the air inside the package during packaging or storage. The research shows that generally speaking, the water absorption of freeze-dried processed food is the largest within 80 hours. At the same time, the moisture absorption is also related to the processing freezing rate and different items

the hygroscopicity of freeze-dried food is related to temperature, air pressure, different food raw materials and other factors, with the supply side structural reform as the main line. In order to reduce the moisture absorption rate, high barrier sealing packaging materials can be selected. The purpose of reducing the moisture absorption rate and extending the shelf life can be achieved by pumping vacuum during packaging and filling special gases (such as nitrogen) into the packaging

2. anti oxidation packaging technology method

the oxidation of freeze-dried food during packaging and storage mainly refers to the oxidation of fat in its components and the oxidation of carotene, chlorophyll and ascorbic acid in oil soluble components. Due to the existence of oxidation, it is difficult to avoid the change of product color and the loss of vitamins

the oxidation degree of fat is more serious when the moisture content is low, because the water molecules adsorbed on the fat are partially broken during drying, which is easy to make the fat surface contact with the oxygen in the air and be oxidized. Therefore, it is difficult to resist oxidation only through the packaging technique of reducing moisture

to sum up, the measures considered for anti-oxidation packaging are to select packaging materials with oxygen absorption function and add antioxidants to make the inner layer of the package have the function of water balance (the inner layer of the package is coated with water retaining agent), so that a certain amount of water can be maintained in the package for low-temperature storage, and packaging materials with good light resistance can be selected at the same time

3. selection of packaging materials

the packaging materials of freeze-dried food should be materials with special functions. The functions of these materials are good sealing and oxygen isolation, strong light blocking, and a certain buffer effect

the preferred freeze-dried food packaging materials mainly include: aluminum foil composite materials, such as aluminum foil and polyethylene composite; Cellophane, polyethylene, aluminum foil, polyethylene four layer composite; Paper, polyethylene, aluminum foil, paper, polyethylene five layer composite; Aluminum foil, polyethylene, polyvinylidene chloride three-layer composite, etc. Metal cans and glass bottles are also used for freeze-dried food packaging. The outer packaging or large packaging are mostly packed in corrugated boxes to achieve the protection purpose of PA) and polycarbonate (polycarbonate buffer and shatterproof).

4. Other packaging measures

(1) put temperature absorbent and oxygen absorbent in the sealed packaging. Hygroscopic agents mainly include: lime, activated carbon, silica gel (natural or synthetic products). Oxygen getters are also called deoxidizers, which are mainly iron deoxidizers and sodium deoxidizers

(2) vacuum packaging method

(3) modified atmosphere packaging method. After the air in the bag (container) is extracted, it is sealed and packed after being filled with nitrogen and other gases

summary

1. Freeze dried food is a new type of processed food with great prospects and market, and its packaging requirements are mainly moisture-proof and anti-oxidation

2. The packaging technology of freeze-dried food mainly adopts vacuum packaging technology and modified atmosphere packaging technology, or adds moisture-proof agent (and PE wax 0.2 parts by weight moisture absorbent) and deoxidizer in vacuum packaging, which is a relatively ideal packaging technology

3. it is particularly important to choose packaging materials, and choose composite packaging materials with good barrier

4. in fact, microorganisms must also be considered in production and packaging, but they are not analyzed emphatically in this paper. Because during freeze-drying, there is often a certain amount of microbial residue, but spores are not formed and revived when there is little water. Once the water increases, they will be revived. Therefore, measures should be taken to sterilize during processing, packaging, storage and transportation, and ensure that the standard sanitary conditions are met. (yangfuxin)

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