Processing is a key step for blueberries to move from agricultural products to commercialization. The use of automated blueberry production lines can achieve higher efficiency and maximize the value of its products. We know that there are many commodity forms of blueberries, but they can be roughly divided into two categories: fresh blueberries and deep-processed blueberries. So let us understand what are the links in the processing of fresh blueberries?
1. Picking
Due to the constraints of various conditions such as the varieties of blueberries, the origin environment, planting technology, and the level of automation, blueberry plantations generally use manual or machine picking.
Correct blueberry picking gesture: The palm should be facing up, and the thumb and index finger should be used to quickly and gently pick the fruit from the fruit stem, so that the fruit rolls naturally into the palm. This posture can maintain the highest picking efficiency without damaging the fruit. But in practice, very few workers can perform it correctly.
Manual picking is a seemingly simple job with a high level of actual technology and difficulty in operation.
Blueberry fruits grow in clusters, and the color is blue-purple when ripe, especially when the sky is cloudy, the color is dark, and the vision requirements for long-term workers are very high. Because it is difficult to ensure that a cluster of blueberries mature at the same time, there are always a few that mature early, and the remaining fruits are green or dark red, which need to be carefully identified.
Blueberry branches are dense, and it is very easy to see the ripe fruits behind because of the obstruction of the front branches when picking. If it cannot be effectively overcome, the fruits that miss the best time to pick because of the obstruction will fall off due to overripeness, causing huge losses to growers.
Some varieties of blueberries have a strong connection between the fruit stem and the fruit. If the operation is not careful during picking, it is easy to cause the skin of the fruit to rupture at the junction of the fruit stem due to tearing, which will cause hidden dangers for subsequent processing. If the fruit stem is directly cut off, it is easy to receive customer complaints due to the existence of the fruit stem after boxing.
In addition, choosing the right time to pick is also a very difficult thing.
After entering the ripening season, blueberries generally enter the expansion stage quickly within two or three days. The size of the fruit is very different before and after expansion. In order to pursue a better appearance and taste, growers hope to pick them when they expand to a certain extent. However, if the degree is not grasped well, picking too late will make the fruit overripe and insufficient in hardness, which is very likely to cause loss in subsequent processing and transportation.
It is worth pointing out that rain is extremely taboo during the blueberry picking period. For any blueberry plantation, precipitation during the picking season will have a catastrophic impact. Rainfall will cause a sharp increase in the difficulty of picking, and the quality of the raw fruit picked by force will also drop significantly, and the possibility of fruit powder, hardness, taste and even subsequent fruit flies will increase significantly. Although the impact of rainfall during the picking season can be reduced to a certain extent by setting up a rain shelter, the construction of the rain shelter is also a pain point that many growers cannot bear due to geographical conditions and economic reasons.
According to statistics, the average speed of manual blueberry picking is 15 to 20 kilograms per hour. If the temperature is high or the weather is rainy, the picking speed will decrease to varying degrees. The picking speed is also closely related to the training level, management ability and proficiency of the base.
After picking, the blueberry raw fruit has been divided into two categories: fresh fruit and frozen fruit, which enter different subsequent processing processes respectively.
2. Precooling
Precooling refers to "a commercial treatment measure that quickly cools the temperature of harvested fruits and vegetables to a temperature suitable for preservation before processing, storage or transportation".
When fruits and vegetables are picked, the temperature is high and there is a lot of field heat. The fruits breathe vigorously and continuously release a lot of respiratory heat. If they are not cooled in time, the ripening and aging of the fruits will be accelerated, affecting storage and transportation, reducing the quality, and even causing rot in severe cases.
Precooling is best done at the place of production, and the sooner the better. Untimely or incomplete precooling will reduce the freshness, flavor and quality of fruits and vegetables. Poland, which has the most developed blueberry industry in Europe, has even set a 30-minute precooling standard: precooling within 30 minutes after blueberries are picked.
Along with precooling, another important process is dehumidification, especially for raw fruits that are forcibly picked in a rainy environment. The common practice is to place the raw fruits with high humidity into a three-dimensional shape in a well-ventilated container, and use a high-power fan to blow air to force the evaporation rate of water on the surface of the fruit to accelerate.
Even for frozen fruit used for deep processing of blueberries, not all blueberry fruits are qualified. There are also many entry standards for the raw materials of frozen fruit. Because the raw fruit of frozen fruit is relatively rough in picking, there are more impurities, and the ratio of green fruit to red fruit is relatively high, it needs to go through the intermediate links of washing, preliminary selection and color selection to complete the first sorting before entering the freezing process.
3. Selection
Selection is a very important process. This process generally pours the raw fruit that has been pre-cooled or frozen onto the conveyor belt. During the conveying process, the workers identify the defective fruit with the naked eye and select it out.
This process is an important checkpoint before sorting and packaging, and has a great impact on the quality of the fruit. Because blueberries belong to berries, if the defective fruit cannot be picked out as much as possible before boxing, the defective fruit can easily spread the defect to other healthy fruits after boxing, thereby greatly shortening the shelf life.
After this process, the raw fruit of fresh fruit will also go through a sorting process, and the raw fruit of different sizes will be separated by a grading machine for subsequent packaging. For raw fruit of frozen fruit, this is not necessary.
4. Sorting
A major feature of agricultural products is poor consistency. Even the fruit on the same blueberry tree will have large differences in size. Friends who are familiar with blueberries know that, generally speaking, the larger the fruit, the better the taste. In order to obtain the greatest benefits, growers also invest a lot of energy in sorting.
Common blueberry sorting is done by automatic sorting machines. The sorting machine sets screening holes of different apertures at different positions on the conveyor belt according to the grading size standards. After passing through the screening area, the fruit will be automatically sorted into fruits of different specifications and concentrated in different containers.
The current domestic grading standards are as follows: fruit diameters below 12mm are small fruits, fruit diameters of 12~15mm are medium fruits, fruit diameters of 15~18mm are large fruits, and fruit diameters above 18mm are special fruits. Corresponding to this standard, the screening apertures on the automatic sorting machine are also divided into three levels: 12mm, 15mm and 18mm.
For a blueberry base, most of the fruits are medium-sized, while the proportion of small and large fruits is relatively small, and special fruits are even rarer. Nevertheless, in order to further highlight the differentiation and increase the overall selling price of the product, some growers with higher planting levels will separate a limited fruit of more than 22mm from the special-grade fruits of more than 18mm.
Blueberries are delicate berries, and the thickness and uniformity of the surface fruit powder have a great impact on the appearance of the product. Fstsort uses a smaller transmission transition and anti-scratch design, which can gently and effectively separate blueberries one by one and transfer them to conveyor belts of different grades. For more information about this sorting equipment, please click on the blueberry grader picture below.
5. Weighing and packaging
There is only one way to pack fresh blueberries: 12 boxes per box, 125g of fruit per box, and a net weight of 1.5 kg for the whole box of blueberries.
There are also two processes for weighing and boxing fresh fruits. One is the last automatic boxing process of a complete set of fresh fruit sorting and processing machinery, and the other is manual weighing and boxing as shown in the figure below.
For frozen fruits, the packaging specification is generally 10kg carton. After simple weighing, the frozen fruits are directly packed into the carton and then imported into the quick-freezing warehouse or freezer for freezing.