Key points and solutions of fresh-keeping packagin

Moon cake fresh-keeping packaging points and solutions

Abstract: moon cake contains a large amount of oil and nutrients, and it is easy to deteriorate if it is improperly packaged. In this paper, the main factors of moon cake deterioration are analyzed in detail, and the solutions that can be adopted in the packaging structure design are given

key words: moon cake, fresh-keeping, microorganism, oil oxidation, barrier in recent years, the "over packaging" of moon cake has become a typical representative of resource waste. With the urgent need of consumers to return to "simplicity" of moon cake packaging, China's upcoming moon cake packaging standards have detailed requirements on the packaging size and cost of moon cakes, which will have a strong impact on the luxury packaging, Make moon cake packaging return to "moderation"

however, scientific and reasonable packaging structure is more necessary to "appropriately package" moon cakes, because moon cakes contain a large amount of oil and nutrients, which are easy to deteriorate if not properly packaged

1. Factors affecting the preservation of moon cakes

moon cakes are the traditional food for the Mid Autumn Festival in China. There are many kinds of moon cakes in China, and the ingredients vary greatly. According to the place of origin, there are Beijing style, Guangzhou style, Soviet style, desktop style, Hong Kong style, Chaozhou style, etc; In terms of taste, there are sweet, salty, salty and sweet taste; According to the stuffing, it can be divided into nuts, rongsha, coconut, fruits and vegetables, jam, egg yolk, etc; According to the cake skin, there are three categories: pulp skin, mixed sugar skin and pastry; As far as the shape is concerned, there are glossy moon cakes, lace moon cakes, etc. Although there are great differences in the composition of various moon cakes, tension and pressure tests are used to detect the tensile, contraction, zigzag, shear, peel, tear, two-point extension and other experiments of the products; The reasons for their deterioration are very similar, mainly due to the excessive microorganisms in the moon cake and the rancidity of the oil (commonly known as "Khara")

1.1 the microorganism exceeds the standard

although there is a high-temperature baking process in the production of moon cakes, and the high-temperature baking can eliminate a large number of microorganisms in the moon cakes and make the moon cakes basically sterile. However, after baking, moon cakes will be subject to secondary pollution from operating environment, processing equipment, operators and microorganisms in packaging materials during cooling, packaging and storage. If no corresponding measures are taken, the microorganisms will rely on the rich nutrients in the moon cakes to multiply in large numbers in the temperature and humidity environment, resulting in the moldy and deteriorated moon cakes. Some literatures point out that microorganisms can propagate rapidly at room temperature, but will be inhibited at high temperature; The oxygen content and relative humidity in the package will have a significant impact on the growth of microorganisms

1.2 oil oxidation

because moon cakes contain more vegetable oils, unsaturated fatty acids in oils can be oxidized by oxygen, resulting in deterioration of moon cakes. Temperature, light and radiation, water content, oxygen concentration and exposure area are the main factors that cause the rancidity of moon cake oil. With the increase of temperature, the oxidation rate of oil will increase; When the moisture content in the moon cake is high or especially dry, it will also accelerate the rate that the slope of wa → WB spectrum is 3dB; The size of the exposed area of the moon cake and the oxygen concentration in the package will obviously affect the oxidation rate of the oil, which is the main factor affecting the oxidation rate of the oil

2. To sum up, moon cake packaging must pay attention to the following aspects:

the first is to reduce the microorganisms in the moon cake as much as possible. At present, the domestic moon cake packaging is mainly through adding antibacterial and bacteriostatic agents in the moon cake packaging that inhibit or kill the microorganisms in the moon cake, packaging and the environment

the second is to minimize the oxygen content in the package. On the one hand, deoxidizer is sealed in the package to effectively remove the trace oxygen remaining in the package during the packaging process. On the other hand, barrier packaging materials with excellent oxygen isolation performance (such as aluminum foil, PVDC, K film and composite film made of them) are used in combination with vacuum or nitrogen filled packaging. Deoxidizer can remove part of the oxygen in the moon cake packaging. The hydraulic system of the concrete pressure tester adopts air-cooled device air, which can slow down the oxidation rate of the oil in the moon cake and inhibit the growth of some aerobic microorganisms, so as to achieve the purpose of moon cake preservation. However, this kind of preservative has higher requirements on the moon cake packaging, and the use cost is also more expensive. In actual use, it can be determined whether deoxidizer is required according to shelf life and storage requirements

thirdly, high moisture resistance materials are used for packaging to reduce the impact on the quality of moon cakes when the environmental humidity is high. It is pointed out in the literature that when the water content of the moon cake is greater than 24%, the microbial contamination bacteria are mainly bacteria and yeast. However, most of the bacteria are anaerobic bacteria, and the yeast is facultative bacteria, so the deoxidizer is invalid for them. Therefore, the shelf life of the moon cake has nothing to do with the specification of the deoxidizer and the amount of oxygen absorbed; However, when the water content is about 18 ~ 20%, the microbial contamination bacteria are mainly molds, which are aerobic bacteria. The use of deoxidizer can effectively inhibit their growth. Therefore, the moon cake can obtain a long storage life. It can be seen that the moisture resistance of the packaging materials must be controlled for the moon cake packaging, otherwise the quality assurance effect obtained by the deoxidization of the moon cake is not ideal

in terms of flexible packaging testing, the gas resistance and humidity resistance of materials are closely related. Although only a few materials have excellent gas resistance and humidity resistance at the same time, for many high gas resistance materials, when the environmental humidity increases, the gas resistance decreases sharply, and nylon and EVOH are more obvious. Of course, if the development of biomedical material industry requiring cold storage strongly relies on the support of advanced technology and economic strength in relevant fields, the gas and humidity resistance of materials should also be tested at low temperature. Only when the temperature is as close as possible to the actual use temperature can the most real and effective data be obtained. For testing the permeability of materials under low temperature, please refer to the article "Application of permeability test in the field of fruit and vegetable preservation" in Languang Laboratory Forum on June 13, 2005

in addition, pay attention to shading. If there is an outer package outside the flexible package, the mechanical performance of the outer package shall also be tested to ensure that the appearance of the contents is intact

3. Packaging cost

it is understood that the new moon cake standard not only requires that the moon cake packaging materials meet the safety and health requirements, but also requires that the moon cake packaging cost should not exceed 25% of its ex factory price. Compared with the current cost of over packaging, which ranges from several times to hundreds of times the price of moon cakes, it seems inconceivable to control the packaging cost within such a small range. Some people may even think that the quality of moon cakes packaged at this cost will not be guaranteed. However, biscuits, deep fried cakes, cakes and other products with very similar composition to moon cakes are sold and packaged with good quality and low price, such as the widely used aluminum foil composite film or aluminized film for the packaging of cookies containing nuts or jam, and the plastic tray for the packaging of egg rolls with aluminized or aluminum foil composite materials. It can be seen that the packaging cost can be controlled at a low price by designing a reasonable and effective packaging structure and using testing equipment to select the most economical packaging materials that can meet the requirements. It is not difficult to realize the "appropriate packaging" of moon cakes

information source: Languang Laboratory