Litchi microwave sterilization preservation technology
Taste delicious lychee pulp , known as the king of fruit . World litchi production of about 270,000 tons , while its international trade of about 16,000 tons per year , accounting for only 5.9% of total output ( taken from Zhang Zhanwei " litchi cultivation " ) . Country both in cultivation and production ranks first in the world , it should be said , the export trade prospects are good , but because of storage and preservation technology behind remote distribution restricted.
Scholars since the 1960s has begun litchi research . They reveal the lychee Browning , but in preservation methods were a breakthrough technology research. For example, the State of Israel fungicide solution processing techniques using fresh litchi , China's Guangxi Province, the end to the Israeli introduction of the whole litchi processing production line. The solution is to use fresh approach .
A fresh litchi microwave mechanism
1.1 lychee cause browning and deterioration
According to the research data indicate spoilage and browning of litchi pulp reasons summarized in the following three aspects:
( 1 ) lychee picking season high ambient temperature ( about 28 ~ 30 ℃), lychee after picking as a living body , the ambient temperature within the pulp contained invertase and polyphenol oxidase activity is very strong, led to rapid litchi pulp softening corruption , it can be said that the rate of softening corruption is "day three changes ."
( 2 ) the outer pericarp after picking fungi and bacteria attached in a suitable ambient temperature growth of reproduction, the formation penetrated flesh peel mildew and quickly accelerated deterioration of litchi .
( 3 ) Lychee from sticks easily after dehydration , prompting browning .
It is recognized that deterioration and browning of litchi reasons , using a variety of methods to prevent lychee deterioration, such as using timed blanching in boiling water method , the use of heat sterilization and inactivating enzymes , or by adding sulfite oxidation and reduction methods to suppress atmosphere oxidase activity , but with little success , because these methods have their limitations.
For example , a conventional boiling water blanching , the processing time is short , the heat conduction is slow, the process results in a short time , the lychee fruit lase difficult to achieve within the temperature and time requirements , if the increase in the heating blanching time , make the outer layer of flesh for a long time to heat, then compromise flavor.
1.2 Mechanism fresh litchi microwave
Preservation litchi microwave microwave energy on the fruit of Litchi integrally , at the same time , the rapid inactivating enzymes , and kill mold , bacteria, characteristics , obtained litchi preservation . Is analyzed as follows :
( A ) the overall microwave heating , research shows that lychee polyphenol oxidase massively distributed within the lychee pericarp and seed in place . Therefore, I want to passivate these distributions in the peel or stone at the polyphenol oxidase, and the flesh must be deep inside , and let the fruit as a whole while meeting the requirements of inactivating enzymes . This is the conventional heating ( boiling ) can not and blanching . The microwave energy can penetrate into the interior of fruit immediately converted to heat , so that the overall heating fruit , temperature uniformity . Microwave heating uniformity of temperature field and the presence of a temperature gradient small features , to meet the requirements of litchi overall passive activity , and can quickly passivation activity. With conventional heating ( water bath ) compared to ( see Figure 2-20 enzyme activity and the heating temperature and time relationship ) microwave method makes oxidase activity decreased 40% , only 1 ~ 2min, while the conventional heating method takes more than 12min , a difference nearly 10 times.
2 fresh litchi microwave experimental results
Lychee with microwave sterilization inactivating enzymes and bactericidal test results , the microwave fresh frozen 23 days after treatment , the color of the case is , the color turn dark , but the flesh firmness unchanged. Also visible microwave preservation treatment, the litchi refrigerated effect.
After 23 days if refrigerated samples still sealed packaging, and stored at room temperature 28 ℃ after three days , the color and flesh firmness did not change . Taste basically unchanged. After 23 days if refrigerated samples open sealed packaging. Then stored at room temperature 28 ℃ for three days, their skin color becomes deeper , but the flesh firmness and flesh color unchanged.
3 fresh litchi microwave core technology and its advantages
Microwave litchi preservation techniques need to solve the following contradiction:
( 1 ) lychee moisturizing and sterilization contradiction .
( 2 ) the whole litchi inactivating enzymes , a short time to inactivate the enzyme and prevent lychee pericarp browning and flesh taste of contradictions.
( 3 ) and refrigeration methods combine to make litchi lychee extend shelf life and prevent changes in skin color and flesh tastes contradiction .
Microwave litchi preservation technology process is divided into two parts: First, by using microwave litchi integrity inactivating enzymes , destroy mildew and bacteria ; Second, gas tuning package and refrigerated ( including refrigerated transport ) . A combination of both to achieve the following litchi preservation effect ; refrigerated storage period of 30 days or more. Good fruit rate of 90 % or more , more than 72h sales shelf , without the use of chemical preservatives, no radioactive residues .
Microwave passivation process characteristics different from the conventional enzyme blanching in boiling water method ; ① it is straightforward to dry inactivating enzymes , no heat medium indirect heating ( such as boiling water blanching ) , easy to operate , clean environment . Also eliminates the need for conventional steam blanching in boiling water boiled , drained blanching kettle and other equipment. Inactivating enzymes within the pulp and peel one for sterilization step outside , take shorter. Lychee conveying continuous operation , low labor intensity suitable for pipeline operations. It does not soak liquid residues.
Microwave litchi preservation processes are the dry state. Production line equipment part is simple, just microwave inactivating enzymes , sterilization equipment, packaging equipment, and transportation equipment. Those produced without wet steam, hot water , containers and pipes and other devices. Equipment investment , low cost, small footprint device .

 

主要产品推荐： 烘干机  干燥机  杀菌机  微波设备