Breeding history and preservation technology of seaweed
The seaweed is delicious and low-calorie food. The seaweed has high nutritional value, contains various vitamins and minerals, and is especially rich in vitamins A and C. It is a popular food. First, the development of seaweed breeding technology in the Japanese seaweed cultivation began in the late 17th century, when the method of cultivation of seaweed is very primitive, about 1926 introduced the laver network, of course, spores are still natural seeding. The modern porphyra breeding technology was developed by Dr. KMDrew after linking the conchocelis filaments with the life history of seaweed. Initially, artificial spores were planted with shell spores in about 1960. Floating-breeding systems were popularized in 1967, and frozen seaweed-net technology was developed in 1969. As a result of the adoption of these techniques, laver production has increased. Due to the development of artificial sowing of shell spores, the seaweed farm has expanded widely. For example, as a result of the introduction of this method, seaweed cultivation began in the Ariake Sea in Japan in 1959 and thereafter became one of the largest seaweed farms in Japan in 1968. Here, the seaweed net is hung between the pillars and called the "pillar-system" site. Later, it was discovered that the growth of seaweed does not need to be continuously dried, so a new method of cultivation of seaweed has been developed. The laver's buoyancy, which floats on the sea, always floats on the sea and is often immersed in seawater. With this method, even if The shallow sea of ​​10-20m depth can also cultivate seaweed, which is called "floating-system" site. The seaweed filaments grow slowly at night when the water temperature is high, and the nighttime temperature is higher in the middle and late November. Under such circumstances, the growth of seaweed was hindered. In order to avoid this loss, a new technology was introduced to store the net deposit in the freezer in the middle and late November. When the laver sprouts grow to 1-3cm in length, the laver net is taken out and dried, and the suitable water content of the fronds is about 20-40%, and it is usually air-dried for 2-3 hours. The laver net is put in a plastic bag and is hidden at -20. °C in the freezer, then place the net in place and continue culturing. Around 1950, various types of fishery machinery became popular. Since about 1977, a variety of "people" type seaweed bread makers have become popular. Chopped seaweed is thrown in from one side of the machine, and seaweed cake is formed on the curtain to squeeze out water. , Drying, and then seaweed cake fell from the net curtain, these processes are fully automated. Due to the combination of new farming methods, mechanization of work and the introduction of rapidly growing varieties, the annual output in 1973 reached 9 billion cakes. The increase in seaweed production is the result of the introduction of seaweed-net freezing, the rapid growth of new varieties, and the popularity of various automatic seaweed-makers. Later, there was an oversupply of seaweed, which required the production of high-quality seaweed. Second, the processing of laver preservation Laver harvest season is limited to the beginning of October to the second year in April, so this season must be preserved seaweed harvest seaweed harvest season in October. This must study the method of quality preservation and the factors that influence the quality reduction in this period. From the aspect of laver quality and nutrition, the effects of water content and temperature on the pigment (such as chlorophyll), carotenoids, phycocyanin, and vitamin C during the preservation period of seaweed were studied. Decrease in chlorophyll is caused by the increase in water content in seaweed and is related to the increase in temperature. If the water content is kept below 6% and the temperature is below 20°C, all chlorophyll can be retained. If the water content is below 6% and the temperature is 30°C, the chlorophyll content will be reduced by 10%. The decrease in carotenoids is similar to that of chlorophyll. However, when the water content of seaweed is less than 6%, the carotenoids significantly decrease when the temperature rises. When the water content of seaweed is less than 6%, the red algae and phycocyanin decrease with the increase of temperature, especially at a temperature of 30°C. When the moisture content of laver is 12%, the temperature is from 0-30°C, and the result of vitamin C reduction is similar. Even at various temperatures where the water content is only 2%, the vitamin C will be reduced. According to the experimental results, vitamin C in seaweed is estimated to disappear completely after 4 months. During the preservation process, the vitamin C content of seaweed decreases with the increase of the water content of the seaweed. When the temperature rises, the trend of vitamin C reduction is more rapid. The water content of 4% of seaweed is the lowest temperature of seaweed. If the seaweed is dried to a moisture content of 2%, the seaweed is automatically oxidized. The production of dry laver has a water content of about 8% or 10%, but later the water content at least increases to 11-12%. When the collection is not good, the water content reaches 15% or more, and the laver cake is placed at a relative humidity of 50%. Under 55% conditions, the water content of the seaweed cake rapidly increases. Therefore, it is necessary to dry the moisture to less than 15% as quickly as possible, and the collection temperature must be reduced as much as possible. In the case of high water content, the quality of seaweed rapidly declines, not only changes in pigment and vitamin C, but also protein content. Therefore, laver packaging must be carried out under low humidity conditions, and packaging should be rapid. Second, the effect of using oxygen-free gas on the quality of laver was studied. The laver sample with 10% water content was stored at 20°C for 6 months. The pigment content was completely preserved, and vitamin C reduction could be avoided in an oxygen-free gas. From these results, to maintain the quality of seaweed, we must avoid moisture, the use of oxygen-free gas preservation is one of the most effective methods. The preservation of anaerobic gasification of seaweed, which is now used for cold storage of dried seaweed and replaced with nitrogen, has become popular. The taste of seaweed is produced by baking. After baking, the color of seaweed changes from reddish purple to blue-green. These results are due to the destruction of phycoerythrin and phycocyanin. After baking, not only the pigment changes but also the cells of the porphyra are changed. This is the reason why the taste of the laver after baking is improved.