What! More than half of the world’s macadamia nuts come from Yunnan?

When it comes to Yunnan nuts, you may be confused, but as soon as you look at the picture, you will definitely feel familiar with it.

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Yes, Yunnan nuts refer to macadamia nuts.

What you may not imagine is that the largest producing area of ​​this nut with the foreign name "macadamia nut" is actually in Yunnan, China, and the planting area accounts for more than half of the world's total.

Image source: CCTV video screenshot

How did Yunnan become the origin of **Macadamia nuts**?

The origin of macadamia nuts is quite complicated. It is native to Australia, so it is also called macadamia nuts (Macadamia spp.). At the end of the 19th century, it was introduced to Hawaii, where it was commercially cultivated and promoted. In the 20th century, Hawaii once became its main production area, so consumers are more familiar with the name - macadamia nuts.

Generally speaking, macadamia nuts belong to the Proteaceae family, a general term for a class of plants. There are about 10 species of macadamia nuts in the world, 6 of which are native to Australia. The main cultivated fruit trees are:

Macadamia (M. integrifolia), also known as "smooth-shelled macadamia", has three leaves arranged in a whorl, with serrated and wavy edges and no thorns, smooth and hairless pericarp, and a smooth seed coat.

The four-leaf macadamia nut (M. tetraphylla), also known as the "rough-shelled macadamia nut", has leaves with hooks on the edges, a rough peel covered with fine short hairs, and a textured seed shell.

The smooth-shell variety is currently widely planted, which has a higher kernel rate and oil yield than the coarse-shell variety and has a better flavor.

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In Australia, the hometown of macadamia nuts, they mainly live in the southeast of Queensland and the northeast of New South Wales. If you look at the map, you will find that these two places are connected and are both subtropical rainforests with a mild and humid climate. Growing under such native conditions, macadamia nuts are water-loving and not cold-resistant, and are quite "picky" about the planting environment.

First of all, it must be moist, and the annual precipitation should not be less than 1000mm.

What does this mean? In my country, areas with an annual rainfall of more than 800 mm are called humid areas, and areas with an annual rainfall of less than 200 mm are called arid areas. In other words, macadamia nuts must be grown in humid areas. If the rainfall is insufficient, an irrigation system must be installed, but this is costly and not environmentally friendly.

Secondly, the temperature should be appropriate.

The average annual temperature should be above 17°C, and there should be no frost period, and it is best not to have a high temperature above 39°C. Especially during the flowering period, if the temperature is too high, the flowering and pollination of macadamia nuts will be affected, and the fruiting rate will be greatly reduced.

In addition, the wind cannot be particularly strong.

There is an interesting saying: Hawaii introduced this tree not for eating nuts, but because it is evergreen and has a dense crown. They wanted to use it as a street tree and windbreak. Unexpectedly, its root system is very shallow and its wind resistance is very poor, so they turned to eating "nuts". The anecdote of that year is no longer verifiable, but what is certain is that there is another condition for growing macadamia nuts, which is to choose a windless area.

With so many restrictions, it is difficult to find a few suitable places in the world, but in Yunnan, China, it is very simple. Yunnan is known for its "three-dimensional climate", which means that there are many types of climates, from the northern tropics to the high and cold mountainous areas. This means that species living in various climatic conditions can find a suitable home in Yunnan.

Macadamia nuts are no exception. The tropical and subtropical areas in southern Yunnan Province, located south of 25° north latitude, have abundant rainfall, sufficient sunshine, mild climate, and are not affected by typhoons. They are very similar to the original production areas of macadamia nuts and are one of the few "golden planting belts" for macadamia nuts in the world.

By the way, let me tell my foodie friends that this is also a golden place for coffee and tea production. Lincang City is the largest macadamia nut planting area in Yunnan, and is also a famous production area for small-grain coffee, Pu'er tea, and Dianhong. It is a place with rich species and magical fertile soil.

Image source: CCTV video screenshot

How did “Macadamia Nuts” in Yunnan Province grow from “zero” to “the largest in the world”?

At the end of the 20th century, macadamia nuts were first introduced to Yunnan Province, where they soon took root. In less than 40 years, Yunnan went from zero to the world's largest planting area.

In addition to a suitable climate, policy support is also needed.

This starts with the long growing period of macadamia nuts. Unlike cash crops such as bananas and sugarcane that can be harvested in the same year, macadamia nuts take at least 5 years from planting to flowering and fruiting, and nearly 10 years to enter the high-yield period.

For the majority of farmers, growing macadamia nuts requires great courage. “Where does the money to buy seedlings come from?” “How can I eat during the long waiting period?” These realistic and urgent questions are before them.

Fortunately, the government and some leading enterprises took the lead in providing farmers with seedlings and technical support. During the long waiting period, some farmers cleverly adopted the strategy of intercropping. Macadamia trees must be planted sparsely, which leaves space in the fields. Before the fruit trees grow up, farmers will intercrop crops such as sugarcane and corn in the fields to maintain their living expenses. When the fruit trees start to bear fruit, they can focus on planting nuts.

There is even a saying circulating in Yunnan that when it comes to nuts, persistence is the key to success.

After more than 30 years of persistence, from screening suitable seedlings to forming a complete and comprehensive cultivation technology, and then to promotion and planting, the people of Yunnan have used their wisdom and courage to explore a path that will bear fruit.

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How did macadamia nuts get their “ smile ” name?

However, it is not enough to just increase the planting area. A complete macadamia nut industry chain also requires supporting processing companies.

The macadamia nuts we usually eat are brown in color with a small hole. When you pry them open, you will find a milky white kernel inside. But the macadamia nuts on the trees do not look like this.

When you go to a macadamia nut planting base, you will find clusters of green fruits on the trees, like a string of small bells. The green part is actually the peel, and the brown macadamia nut hidden inside the peel is what we commonly see.

When the green fruit is ripe, it will fall to the ground and the skin will crack, just like the small cracks on the chestnut thorn ball when it is ripe. More than 200 years ago, the Australian Aboriginals would pick up these green fruits that fell to the ground. As long as they peeled off the skin, they could get delicious macadamia nuts.

Of course, in that era when there were no openers, the indigenous people had to put in some effort if they wanted to eat the milky white kernels inside.

From left to right: macadamia green fruit, a ripe fruit with cracked exocarp, a fruit with only the endocarp left after the exocarp is removed, and a kernel. Image source: Public Domain, Wikimedia Commons

In today's large-scale planting, it is obviously unrealistic to peel the fruit by hand because the quantity is too large. In addition, after the green fruit is harvested, the peel must be removed as soon as possible, otherwise it will easily become moldy.

Another key point is that fresh nuts have high moisture content and need to be dried as quickly as possible, otherwise the fruit will easily germinate. These three points require a modern factory that can use automated production lines to quickly complete the processes of transportation, peeling, cleaning, water flotation, drying, etc.

After completing these basic processes, macadamia nuts will be sent to the assembly line with "blades" to make a cut in the shell, which is the common "open smile" for consumers. As long as you don't lose the "small iron piece" in the packaging bag, you can easily enjoy the convenience of modern processing technology.

In fact, fresh macadamia nuts have a light milky flavor, but the milky macadamia nuts we eat everyday are not the original flavor, but seasoned products. It is said that mustard flavor, seaweed flavor, and matcha flavor have also been developed. Friends who like to explore new things may wish to try them.

With the development of processing technology, macadamia nuts are no longer just a snack eaten during the Chinese New Year. They have also been made into cosmetics, cooking oil (fat content is 75% to 79%), essential oil, and so on.

A tiny seed contains such rich vitality. It can grow into a big tree or evolve into a wide range of commodities. In this vibrant place south of 25° north latitude, this seed is leading the people of Yunnan towards a more abundant future.

Planning and production

This article is a work of Science Popularization China-Starry Sky Project

Produced by: Science Popularization Department of China Association for Science and Technology

Producer｜China Science and Technology Press Co., Ltd., Beijing Zhongke Xinghe Culture Media Co., Ltd.

Author: Cheng Guan, Master of Biology, Imperial College London

Review丨Gu Yourong Associate Professor of the School of Life Sciences, Capital Normal University, PhD in Botany, Chinese Academy of Sciences

Planning丨Lin Lin

Editors: Lin Lin, Yang Yaping