Macadamia spp., also known as magnolia, Australian walnut, or Queensland chestnut, is native to the subtropical rainforest of southeastern Queensland and northeastern New Zealand Wales. It is a perennial evergreen tree in the family Proteaceae, belonging to the genus Macadamia. muell. Macadamia nut fruits include green skin (green skin), brownish red shell, and milky white kernels, with green skin accounting for 45% to 60% of the fresh fruit weight. Due to the high moisture content in green skin, it is not conducive to long-term storage. Existing Macadamia nuts need to remove the green skin after picking to prevent excessive moisture content from causing Macadamia nut decay. The edible part of macadamia nuts is the kernel, which has a fat content of over 72% and is also rich in protein, calcium, phosphorus, iron, B vitamins, thiamine, riboflavin, and niacin. Fruit kernels contain 17 types of amino acids, which are nutritious and delicious. They are one of the best quality nuts in the world and are known as the "King of Nuts".
At present, most of the processed macadamia nuts on the market are dried fruit products after removing the green skin, such as open shelled macadamia nuts and dried fruit kernels. The moisture content of the kernels in these dried fruit products is required to be below 1.5%. Macadamia nuts are a type of nut with high calorie content. The existing dried fruit products of Macadamia nuts are dry, fragrant, and greasy. Eating a little too much can easily lead to body heat and cause swelling and pain in the throat and gums. The high fat content in dried fruits can also lead to body fat accumulation. But consuming small amounts does not meet the nutritional needs of people to supplement macadamia nuts. Moreover, research has found that dried macadamia nut products that undergo excessive drying processes can cause deterioration or loss of nutrients and functional components.
With the continuous expansion of the planting area and production area of macadamia nuts in China, the yield of macadamia nuts is also increasing year by year. In order to meet the market demand, the deep processing and new product development of macadamia nuts have become very necessary and urgent. When the moisture content of macadamia nut kernels exceeds 5% or more, they can be called fresh nuts. Fresh macadamia nut products processed on a fresh basis may solve the problem of easy ignition due to their relatively high moisture content. Therefore, developing fresh macadamia nut products will become a new way out in the current nut market.
At the 2017 China International Nut Conference, experts and industry insiders unanimously believed that the market would ignite a wave of fresh nut consumption. Although people have always longed for the processing of fresh macadamia nut products, due to the high moisture content of macadamia nut kernels, which is generally higher than 5%, the enclosed and adhered macadamia nut kernels are prone to enzymatic browning reactions and the growth of microorganisms such as molds, making it difficult to preserve the freshness of their fresh products in industrial production. At the same time, fresh macadamia nut kernels are difficult to separate from the shell, Its edibility and convenience are extremely poor, and so far there has been no fresh macadamia nut product on the market.

The most typical representative that can be processed fresh in nut products is fresh walnuts, which have the characteristics of high moisture content in the nuts, crispy and delicious taste in the fresh products, and sweet taste. At the same time, fresh walnuts effectively avoid the disadvantage of dry walnuts being easy to catch fire after eating too much, and have been loved by consumers and occupy an increasing proportion in the nut market. The moisture content of fresh walnut products is also high, but the reason why they can enter the market quickly is because there is a coating film on the outside of the walnut kernels, which makes it easy for the walnut kernels to be directly separated from the shell, thereby ensuring the edible and convenient nature of fresh walnut products, and ensuring the crispy taste of fresh walnuts.
Compared with fresh walnut products, the reason why fresh macadamia nut products have not yet been developed is not only because of the difficulty in preservation mentioned above, but also because the nuts and shells of macadamia nuts are tightly adhered to each other, rather than the existence of a coating film between the nuts and shells of fresh walnuts, which can easily and perfectly remove the nuts. When retaining a high water content in the kernels for processing and preparing fresh macadamia nut products, it is not possible to effectively separate the kernels from the shells, which greatly affects the edible and convenient nature of fresh macadamia nut products, and seriously affects the taste of fresh macadamia nut products, resulting in the absence of fresh macadamia nut products on the market, But people have always longed for a fresh macadamia nut product to replace the problems of easy ignition and high calorie caused by its dried fruit products.
Therefore, in order to develop fresh macadamia nut products, it is necessary to solve the preservation and antibacterial problems of the wet kernels of fresh macadamia nuts, as well as the problems of poor edibility and convenience caused by the tight adhesion between the wet kernels and the shell. Currently, there is no solution to these two problems, which have become urgent technical problems in the field of fresh macadamia nut product processing.