According to the point of view of traditional Chinese medicine, people with yin deficiency and excessive fire and damp heat constitution should not eat it. Especially in Lingnan area, there has been a saying that "one litchi has three fires" since ancient times. Eat more lychees, ranging from sore throat and nosebleeds to death.

Su Dongpo of the Northern Song Dynasty was accused of "scorning the first dynasty" and was demoted to Lingnan. Because "you can't sign books and business", you suddenly have poetry and distance. When I have nothing to do, I will send my feelings to the mountains and rivers, and write down the endless "3 branches of the sun, and I will not hesitate to be a Lingnan person."

However, someone with a good deed once estimated that 3 lychees must weigh at least 2 kilograms. If you eat them all, it will be worth your life. But in the eyes of the Han emperor, Lingnan litchi has the effect of prolonging life. Lingnan litchi was paid tribute to the imperial court in the Han Dynasty

at the beginning of the Han Dynasty, and Lingnan litchi was paid tribute to the imperial court as a tribute. Due to the lack of preservation technology, we can only pay tribute to dried litchi. Since litchi has a "special effect", it is a great pity not to taste fresh litchi.

According to the Records of China Agricultural Legacy, during the period of Emperor Wu of the Han Dynasty, the court decided to try to transplant litchi to Chang 'an. As a result, not only was it acclimatized, but the whole plant was directly frozen to death in winter. Fresh litchi from Lingnan was transported to Beijing, and it was not really implemented until the Eastern Han Dynasty and Emperor.

The Eastern Han Dynasty and Emperor Liu Zhao have a special liking for Lingnan Jiaguo, and almost all of them take "express delivery" in the same season. According to Zhong Changtong's "Zhong Changzi Chang Yan" in the Eastern Han Dynasty, "Today's people don't think about manna, and the springs are overflowing. And suffering from the rot of loquat and litchi is also embarrassing. "

Liu Zhao wanted to eat and worried about fruit rot, so he ordered someone to ride a fast horse from Lingnan to Beijing day and night. But even so, when it arrived, it was rotten, and the taste and quality of the rest were greatly reduced.

In ancient times, Lingnan was a place of miasma, and there were many poisonous insects and beasts. The litchi eaten by Liu Zhao was picked and shipped from Lingnan, while the longan demanded a tribute from Jiaotoe County (now northern Vietnam), which is farther away. After a long journey, many people and horses were killed and injured.

in the end, some ministers really couldn't stand it, and wrote to Liu Zhao to cancel the tribute to fresh lychee and longan, saying, "See the seven counties in Jiaotoe offering longan and so on, and the birds are shocked." In the land of Nanzhou, there are endless insects and beasts, and as for the harm of death. These two things may not prolong life, and the emperor will follow them. " Great progress has been made in fruit preservation technology in the Tang Dynasty, and Emperor Xuanzong of the Tang Dynasty restarted the transportation of litchi from Lingnan to Beijing

"Riding a princess in the world of mortals and laughing, no one knew it was litchi". Since Tang Xuanzong liked Yang Guifei, he loved her very much. When he knew that Yang Guifei loved fresh branches, he did not hesitate to restart the delivery of litchi from Lingnan to Chang 'an.

Some scholars in later generations believe that the litchi that Yang Guifei ate was not picked from Lingnan, but was in Meishan, Sichuan, where she was born. However, this view is like that Yang Guifei is from Rong County, Guangxi, and there is no evidence.

Although Tang Xuanzong transported litchi from Lingnan to Chang 'an, it took the same "expressway" as Liu Zhao in the Eastern Han Dynasty, that is, the Xijing Ancient Road built in the second year of Jianwu in the Eastern Han Dynasty, the national strength of the Tang Dynasty was much stronger than that of the Eastern Han Dynasty.

In his poem "Sick Orange", Du Fu, a contemporary, said, "Recalling the past ambassadors in the South China Sea, rushing to offer litchi branches. A hundred horses died in the valley, and it is sad to this day. " The poem. The preservation technology of litchi in Tang Dynasty was enough for Yang Guifei to eat fresh litchi.

When the New Tang Book describes the arrival of branches, it still keeps "the same color and taste". The reason is that the preservation technology of litchi in Tang dynasty was adopted, which is a pot sealing technology. This method is different from the bamboo tube sealing method for transporting oranges, and the fresh-keeping effect is better.

However, its fresh-keeping time is just that. After litchi arrives in Chang 'an, if it is not eaten immediately, it will rot if it is parked for a while. "Tang Guo Shi Bu" clearly pointed out this point, "The imperial concubine loves litchi, and the South China Sea flies every year to advance, but it is cooked in the summer and defeated by the night. Later generations don't know it. "

since the song dynasty, the preservation technology of litchi became more and more mature.

in the song dynasty, the preservation method of litchi was changed from that of the Tang dynasty, and two preservation technologies appeared. One is the method of spreading a thick layer of litchi leaves in bamboo cages for long-distance transportation described by Cai Xiang in the Northern Song Dynasty, and the other is the "? Seal its branches "method.

In the Ming and Qing dynasties, various preservation methods appeared one after another, such as cutting off plantains, rooting them in, sealing mud with live bamboo or wrapping them with zongzi leaves, etc. Conclusion:

In ancient times, there were no advanced means of transportation, but the ancients were still able to create various preservation technologies with their wisdom, which was really commendable. Introduction

"Chang 'an looks back and embroiders are piled up, and thousands of doors are opened at the top of the mountain. As soon as I rode on the world of mortals and laughed, no one knew it was litchi. " This is the famous poet Du Mu in the Tang Dynasty who wrote "Crossing the Qing Palace". Its core idea is to satirize the fact that Emperor Xuanzong of Tang Dynasty spared no expense to satisfy Yang Guifei's desire to eat litchi.

Su Shi, a famous poet in the Song Dynasty, once wrote in Eating Litchi that "3 lychees are planted every day, and you will grow up to be a Lingnan person". After this poem, many people combined the poems of Du Mu and Su Shi, forming a kind of litchi that Yang Guifei ate was transported from Lingnan. Analysis

In ancient times, if the food provided to the palace could not be guaranteed, it was in danger of decapitation. However, the technology at that time could not transport litchi from Lingnan to Chang 'an to ensure the quality. But there is a clear record in history that Yang Guifei likes to eat litchi: < P > How did this happen?

there is a fundamental reason why this can be done, and that is, the litchi that Yang Guifei ate did not arrive in Chang 'an from Lingnan.

Lingnan in Su Shi's works is the generation of Guangxi and Guangdong today. According to today's conversion standards, it is also more than 1,5 kilometers from Guangdong and Guangxi to Chang 'an.

1,5 kilometers, that's 3, miles, and there are highways today. However, it was impossible for the Tang Dynasty to clear the way for the mountain and bridge the bridge when encountering water as it is today. Therefore, the distance from Lingnan to Chang 'an is much more than 3 Li. Even the fastest horse and the advanced fresh-keeping technology, litchi has gone bad on the way from Lingnan to Chang 'an.

Therefore, the litchi that Yang Guifei eats is not Lingnan litchi, but Fuzhou litchi:

Fuzhou is today's Chongqing generation, while Yang Guifei grew up in Shuzhou, today's Sichuan generation. Geographically, Yang Guifei should have eaten litchi in Fuzhou when she was a child, but she continued her diet hobby after entering the palace. This is in line with people's physiological and psychological development needs.

Let's take a look at the distance from Fuzhou to Chang 'an. According to today's calculation dimension, the distance from Fuzhou, which is now Chongqing, to Chang 'an should be about 7 kilometers, which is 14 miles. It is more than half the distance from Lingnan to Chang 'an.

during the Tang dynasty, Sichuan and Sichuan had close communication with the capital, and this section of traffic lines was also relatively developed. It is much less difficult to transport litchi from Fuzhou to Chang 'an than from Lingnan to Chang 'an, and it is easier to complete under the background of productivity at that time.

therefore, I will give the first conclusion first. The litchi that Yang Guifei ate was not from Lingnan to Chang 'an, but from Fuzhou to Chang 'an.

Tell a song about Emperor Xuanzong of Tang Dynasty to Yang Guifei, which is really "Love You with My Whole World". First, the princes of Zhou Youwang bonfire drama praised and smiled, and later, Emperor Xuanzong of Tang Dynasty developed litchi road to satisfy the imperial concubine's appetite. In order to please women, ancient emperors really spared no expense.

In order to let Yang Guifei eat litchi as quickly and best as possible, Emperor Xuanzong of Tang Dynasty made a little change on the basis of the original post office and developed a litchi road.

The so-called Litchi Road was not named by Emperor Xuanzong of the Tang Dynasty, but by later generations, the ancient land commercial and trade route connecting Sichuan, Shaanxi and Hubei from Fuling to Kaizhou in Wanzhou, Xuanhan County in Tongzhou and Yangzhou Road to Chang 'an for 2,24 miles was named Litchi Road. The reason for this name is that Xuanzong's original intention is to deliver litchi to Yang Guifei.

How long will it take to transport litchi to Chang 'an on the Litchi Road developed by the state?

It takes seven days to get to Chang 'an, which is recorded in many documents. However, I have some doubts about this. In seven days, it is very difficult for litchi to keep fresh under the ancient technical level, and it takes less than seven days for the 22-mile ancient fast horse.

What I recognize more is the following record:

There are two reasons for choosing this record.

From the geographical point of view, three days is more reasonable than seven days, and it is more in line with the requirements of Xuanzong of the Tang Dynasty. On the other hand, Yu Di Ji Sheng, which recorded three days, was written earlier than Fu Zhou Zhi, which recorded seven days, and the historical materials are more credible.

In this case, we can know that it should take three days for litchi to be transported from its producing area to Chang 'an. This time is not long, and it may be able to keep fresh according to the productivity at that time.

Litchi, a fruit, has been recorded since the Han Dynasty. In Sima Xiangru's Shang Lin Fu, it was written as a branch. Later, Bai Juyi explained this:

From this point, we can see that the ancients have found that litchi can not be preserved without this branch. Therefore, when we eat litchi today, we often see that it still needs to be picked together with this branch. The purpose of doing this should be to keep fresh.

According to Bai Juyi's writing, plus my interpretation of litchi transportation routes above, we should be able to find a problem. If litchi arrived in Chang 'an from Fuzhou within three days, the difficulty of preservation was not as great as we thought.

but after all, it's a tribute to the royal family, and we still need to use our brains in preservation.

In fact, the ancients had long dabbled in food preservation. According to an article in the Book of Songs, we can see that in the Shang and Zhou Dynasties,

the ancients had a sense of preservation.

According to the records in Sui Shu,

When keeping litchi fresh, Emperor Xuanzong of the Tang Dynasty may learn from the method of keeping oranges fresh by Emperor Wendi of Sui Dynasty.

In addition to wax sealing, the ancients also had one of the most commonly used preservation methods, that is, using "ice" to keep fresh. The history of keeping fresh with "ice" can be traced back to the Zhou Dynasty. By the Tang Dynasty, ice had been widely used, and even "ice" was used as a business:

But in today's archaeological discoveries, people found many iron boxes with compartments. There are signs of "ice" stored between the compartments of this iron box. Many people regard this kind of compartment iron box for storing ice as the early embryonic form of refrigerator.

It can be inferred that when keeping litchi fresh in the Xuanzong period of Tang Dynasty, Emperor Wendi of Sui Dynasty should adopt the method of wax sealing and the refrigerator of interlayer iron box.

P.S.: I also want to say that the taste of fruits in ancient times was quite different from that of today. Because of the gap in planting technology, it is far from today in terms of sweetness and moisture.

and an important reason for fruit preservation is to keep its moisture. If the moisture in the fruit itself is not so abundant, the difficulty in preservation will be reduced. Conclusion

Xuanzong in the early Tang Dynasty was a generation of wise kings. If it is carried forward, it is not impossible to become a generation of saints. However, the appearance of Yang Guifei made Tang Xuanzong sink. Just eating lychee, Emperor Xuanzong of Tang Dynasty wasted people and money, just to satisfy Yang Guifei's appetite.

The wisdom of the ancients was so exploited and used by the ruling class. When I think about it, I only sigh all my life.

Thank you for your invitation. [Yi Ya] It is said that there are many post stations to be built along the way, which are less than a few kilometers apart. Express delivery is fast and fast, and the princess smiles [covers her face]. Express delivery brother, and all the horses have sacrificed [tears] [tears] [tears]

There are many ancient capitals in China, including Xianyang, Xi 'an, Luoyang, Beijing, Kaifeng and Nanjing. In history, only Yang Guifei likes litchi the most. When it comes to sending litchi from Lingnan to Beijing, the capital at that time is now Xi 'an. You said it would take a few days at the earliest. Even if litchi was sent from Guangzhou to Chang 'an, the only way to go north in that year was Meiguan. The journey from Guangzhou to Chang 'an was more than 2,5 kilometers. Even the fastest horse had to run for a week, and the litchi was dried before Yang Guifei. Su Dongpo also questioned this matter in those days. He thought that Lingnan litchi could not be sent to Chang 'an because it was too far! But Yang Guifei likes litchi very much. Yang Guifei was born in Meixian County, Sichuan Province. When she was 8 years old, her uncle took her to Luoyang. Yang Guifei likes litchi, which proves that she had eaten litchi before she was 8 years old. I believe that she has never seen anything but litchi in Chang 'an City. In fact, there are lychees in Meixian County and Luzhou, Sichuan Province, and Meixian County is only 7 kilometers away from Chang 'an, which can be delivered in two days by fast horse, so I think the lychee that Yang Guifei ate is the lychee produced in Sichuan.

Don't underestimate the wisdom of the ancients. There are many ways for the ancients to keep fresh:

First, move the whole tree.

Dig up the whole tree when the litchi is about to ripen, and take protective measures. If it belongs to Lingnan, it will be transported by water first. When it reaches the south of Shaanxi, the fruit is almost ripe, so it can be picked and sent to the palace one day.

Second, bamboo tube preservation

First, wrap the litchi with branches with bamboo papyrus and wet it. Then put it in a big bamboo tube and seal it with wax. This preservation time is about one week, and it can be sent to the palace from Guangdong or Sichuan. This has been tested today, and it can be done.

Litchi is also called off-branch, that is, you can't leave the branch. Bai Juyi has a saying: If you leave the branch, the color will change in one day ... the color and fragrance will be gone in four days and five days, so the core of this preservation is not to cut off the branch, and the second is to seal it.

Third, pruning and wax sealing method

First, cut it off, leave some stalks, seal it with wax, then cut off the stalks and seal it. Then soak it in honey. This is said to keep fresh for several months. Although there is no textual research, this method belongs to isolating air and preventing oxidation, and there is still a scientific basis.

So, don't think it's difficult to keep fresh. What's difficult is the inconvenient transportation in ancient times. It's inevitable that the knight who sent litchi over the mountains will be dangerous and expensive. Therefore, Du Mu sneered: "When riding a princess in the world of mortals, no one knew it was litchi."

There is a variety called Feizixiao in Gaozhou, Guangdong. According to legend, Yang Guifei loved lychee in the Tang Dynasty, so she sent it in a thousand miles.

The capital of the Tang Dynasty is in Xi 'an, which is about 2, kilometers from Guangdong. You can only use the official post office, the post office, and hurry up. Every time you go to a post station, you change horses. Immediately relay to send. Therefore, the concubine laughs at this variety of litchi, even if it is mature, there will still be green. Litchi like this should be picked without being too ripe. Add packaging and send it to Beijing for 2-3 days. Litchi is still edible!

bamboo tube, add ice, add horse to rest.

I wonder why I wrote such a simple question.