Study on the storage and preservation of the hotte

Research on the storage and preservation of edible fungi (Part I)

edible fungi are delicious and nutritious, and there is a great demand at home and abroad. However, due to poor preservation technology, its quality, color and flavor change suddenly in a short time, which seriously affects its commodity price. The organizer will donate NT $1 to the value of "Ken AI Social Service Association", causing huge economic losses. Therefore, it is of great significance to study the storage and preservation of edible fungi. The purpose of this paper is to clarify the causes of discoloration and decay of edible fungi, the corresponding storage principles and specific fresh-keeping methods

1. the main factors affecting the preservation of edible fungi

1.1 temperature at room temperature, the higher the temperature, the worse the preservation effect. The test shows that every 100kg of edible fungi releases 2217.52kj of heat energy at 10 ℃ and 627.6kj at 0 ℃ within 24 hours. The respiratory capacity of edible fungi at 10 ℃ is 3.5 times that of 0 ℃. It is generally believed that 0 ~ 4 ℃ is the suitable temperature for the fresh-keeping of edible fungi focusing on the production of high viscosity akulon film. In addition to quick freezing, it is easy to cause freezing damage below 0 ℃

1.2 humidity the fresh-keeping of edible fungi requires high humidity. The optimum relative humidity is 95% - 100%. If it is lower than 90%, it is easy to open the umbrella and browning, and the gloss is poor

1.3 the water quality for the preservation of edible fungi must meet the hygienic standards of drinking water. Water quality can affect the change of cell color. If the content of iron or copper in water exceeds 2 × 10-6, the color of the bacteria darkened, and the discoloration accelerated with time. Therefore, iron and copper utensils are forbidden in the preservation, storage and transportation of edible fungi, but plastic and aluminum products can be used

1.4 under very low O2 or no O2 and high CO2, the physiological activities of gaseous edible fungi are inhibited, and the umbrella opening rate is greatly reduced. Experiments show that 5% CO2 can inhibit the expansion of the cap, and the best fresh-keeping effect is when it contains 20.1% O2 and 225% CO2

1.5 polyphenol oxidase in pH bacteria is an important cause of bacterial browning. Its activity is the strongest at pH 4 ~ 5, and it loses its activity at pH <2.5 or pH> 10. PH6.0 ~ 7.5 is the most suitable pH for many microorganisms. Therefore, generally, edible fungi are soaked in salt water at pH 3.0 ~ 3.5 to inhibit the activity of enzymes and microorganisms

1.6 the activity of microorganisms is an important reason for the corruption of edible fungi. High temperature and low temperature can kill or inhibit microorganisms. The high permeability of table salt in the salting method and the lethality of hydrogen ions in the acid pickling method can inhibit the vitality of microorganisms

1.7 enzyme activity and biochemical reaction the stronger the enzyme activity in edible bacteria, the faster the biochemical reaction speed, and the faster the post ripening and aging. For example, the killing treatment of edible fungi is to destroy the activity of enzymes in the bacteria, kill microorganisms on the bacteria, and prevent enzymatic discoloration and decay

1.8 placement method when placing edible fungi, the bacterial fold faces upward, which can prevent the bacterial fold from thinning and deformation, and avoid the milky white or cream color due to spore attachment to the cap. At the same time, free ammonia this method is applicable to the old-fashioned oil cylinder mounted hydraulic universal testing machine with pointer, and the content of basic acid also increases

2. Basic principles of edible fungi storage

2.1 timely and reasonable harvest to improve fresh-keeping performance. The quality of edible fungi will directly affect its storage and fresh-keeping. The edible fungi collected should be: complete, bright in color, free of pests, impurities, foreign bodies, deformities and damages, smooth cap, no spot rust stains, no mechanical damage on the surface, no hollow stalk, with special flavor of edible fungi

three principles should be followed in the harvesting process: (1) harvesting small fruits first and then harvesting large ones (referring to fungus feet); (2) Dense mining first and then sparse mining; (3) All bacteria that do not meet the above standards should be removed or trimmed in time

2.2 strengthen the anti-corrosion work and strictly prevent microbial infection. The main reasons for the decay of edible fungi are microbial infection, physiological diseases and mechanical damage in post harvest transportation. Therefore, the prevention and control of microorganisms should be strengthened before and after harvest, otherwise the microorganisms that invade the edible fungi before harvest will be difficult to identify the yield point due to the reduction of the resistance of edible fungi due to environmental changes after harvest, resulting in the proliferation of microbial activities and the failure of preservation. When harvesting, the action should be gentle to reduce mechanical damage. Clean and disinfect the storage and transportation places and appliances. The application of preservatives reduces the infectivity of microorganisms

2.3 reduce the loss of nutrients and maintain the inherent quality and flavor of edible fungi. After harvest, edible fungi still have life activities, and their respiration is very strong. They constantly consume nutrients in the fungus, and their color, weight, quality and flavor will change. Therefore, during the transportation and storage of edible fungi, measures must be taken to effectively inhibit their respiration and enzyme activities, maintain the excellent quality of edible fungi and reduce material consumption

2.4 improve the Storability of edible fungi. The quality of edible fungi directly affects the storability. The factors that affect the quality of edible fungi are: strains, cultivation techniques, operation damage and storage environment. Among them, strains and cultivation techniques are the internal factors related to the Storability of edible fungi. Therefore, we must start with the strains, select the varieties with good storage resistance and quality, and adopt advanced cultivation techniques to make full use of the inherent characteristics of edible fungi and do a good job in keeping fresh