In addition to fresh marketing, a part of the blueberry fruit is also used for processing into products. At present, blueberry products include wine, beverages, jams, snacks, etc.
Drying methods
1.vacuum freeze drying: the blueberries are cooled and frozen in advance and put into the vacuum chamber of the food freeze dryer for drying, the vacuum degree is about 10Pa, the cold trap temperature is -42℃, drying until the final water content of blueberries is 3±1% end.
2.Hot air drying: the fresh blueberries are evenly spread in trays within the drying oven, the oven temperature is set at 60°C, the drying time is about 16h, the moisture content within the blueberry fruit after drying is 15±1%.
Effect of different drying methods on the rehydration ratio and microstructure of blueberry
As can be seen from Figure 1, the rehydration ratio gradually increased with the extension of rehydration time, but the rehydration of blueberry fruits after freeze-drying was significantly greater than that of Hot air dried products. At the early stage of rehydration, the samples rapidly absorbed water, and after 5 min, the blue rehydration of the vacuum freeze-dried samples was significantly better than that of the hot air-dried samples.
The rehydration ratio was 1.57 and 1.14 respectively; after 20 min, the rehydration ratio of both samples almost stopped increasing, indicating that the rehydration was over.
At this time, the rehydration ratio of vacuum freeze-dried blueberry was as high as 2.15, while the rehydration ratio of hot air-dried blueberry was only 1.21. From Figure 2-A, it can be seen that
This method has a low degree of damage to the flesh structure, and can remove the flesh from the blueberry tissue.
low, which can dissipate the ice crystals in the blueberry tissue directly by sublimation, resulting in irregular arrangement or separation of cells and good tissue deformability, thus
This structure is conducive to the retention of water in the process of rehydration and has good rehydration, while the pores of the blueberry products treated by hot air drying can be reduced to a minimum.
The pores of blueberry products treated by hot air drying are very small, and due to the prolonged hot air drying treatment, the texture of blueberry is damaged to a greater extent, and the structure is tight.
As a result, the structure of the blueberry was not restored to its original structure after rehydration, and the rehydration performance was poor (Figure 2-B)
Kassel is a professional manufacturer and dedicated to provide our customers with R&D, production, selling& after-sales service as a turnkey solution with our customers.Our industrial blueberry freeze dryer (1㎡to 200㎡） are widely used in the food, pharmaceutical and cosmetic industries and have been widely recognised and praised for their efficient, stable and reliable performance.
Our lyophilisers are equipped with advanced technology and high quality materials, and feature highly efficient refrigeration systems, intelligent control systems and safe and reliable operating systems to meet the needs of different customers. We can also customise our machines according to customers' special requirements to meet their individual needs.
We always adhere to the tenet of "quality first, customer first" and constantly improve the quality of our products and services in order to meet the needs and expectations of our customers. We welcome customers to consult and negotiate with us for mutual development and win-win cooperation!
If you have any question about fruits freeze dryer ,
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