The essence of vacuum freeze drying of Broth of white fungus is to first boil it into soup, then freeze it at low temperature, and finally vacuum sublimation dehydration. It is more difficult to make than tremella pieces, because Broth of white fungus contains polysaccharide, gum and sugar, high viscosity, many solids, easy to collapse, stick to the plate, and slow rehydration. In terms of craftsmanship, it is necessary to control the "boiling concentration, plating thickness, pre freezing permeability, sublimation rate, and analytical endpoint" in a series.

Overview of vacuum freeze drying of tremella soup:
The essence of vacuum freeze drying of Broth of white fungus is to first boil it into soup, then freeze it at low temperature, and finally vacuum sublimation dehydration. It is more difficult to make than tremella pieces, because Broth of white fungus contains polysaccharide, gum and sugar, high viscosity, many solids, easy to collapse, stick to the plate, and slow rehydration. In terms of craftsmanship, it is necessary to control the "boiling concentration, plating thickness, pre freezing permeability, sublimation rate, and analytical endpoint" in a series.
Vacuum freeze-drying production process of tremella soup:

The purpose of the key control points in the process is to select fresh or high-quality dried Tremella fuciformis for raw material pretreatment, clean, remove stems, soak, and cut to ensure the release of gum and stable batch. The ingredients are boiled with red dates, wolfberries, rock sugar, etc., and simmered over low heat until a stable soup is formed. The solid ratio is stable. After cooling and packaging, the material is quantitatively loaded onto a tray/mold with uniform thickness to ensure even freezing and drying. The pre freezing temperature is -30 ℃ to -45 ℃, and the center temperature is lower than the eutectic point. The moisture is completely frozen to prevent collapse, foaming, sublimation, and drying. The vacuum is about 10~40Pa, and the shelf is slowly heated to remove about 90% of free water. The analytical drying is 40~60 ℃, and the vacuum is 20~30Pa to remove bound water. The moisture content is reduced to 3 Nitrogen filling/aluminum foil sealing for moisture resistance, oxidation resistance, and rehydration retention in wet environments. Moisture retention, rehydration, sensory, and microbiological testing of samples Ensure stability and traceability of finished products
Vacuum freeze drying process of tremella soup:

The boiling concentration should be fixed, and the Broth of white fungus should not be too thin, otherwise the freeze-drying cycle will be long and the energy consumption will be high; It cannot be too thick, otherwise the heat will be uneven after loading, and the center will easily freeze and not be fully penetrated. Suggest fixing the ratio of Tremella fuciformis, water, sugar, and excipients, and conducting small-scale tests to verify the solid content. The thickness of the plating should be uniform. The thicker the soup, the greater the sublimation resistance. Quantitative molding can ensure consistent taste after rehydration of each piece, and also facilitate subsequent calculation of net content and brewing water volume per package. The pre frozen Broth of white fungus must be thoroughly frozen. It should be pre frozen in the quick freezing warehouse or freeze-drying machine to make the central temperature stable below the eutectic point. The common practice is to pre freeze at -30 ℃ to -45 ℃, depending on the thickness of the optic disc layer and the equipment capacity, and not just on the surface freezing. During the sublimation stage, the temperature should not be too high. When drying once, the vacuum degree is usually controlled at around 10-40Pa, and the shelf temperature slowly increases from the low temperature range. If the temperature rises too quickly, the surface will first crust, and the internal water cannot be released, resulting in collapse, poor honeycomb structure, and slow rehydration of the finished product. After analyzing the final moisture content determined by drying and sublimation, the material still contains bound water. The analysis stage can be raised to 40-60 ℃, and the vacuum degree can be further stabilized at around 20-30 Pa until the moisture content drops to 3% -5%. The endpoint cannot be determined solely by time, it is best to combine pressure rise testing, material temperature, and moisture content testing. The discharging and packaging environment should be low humidity and freeze-dried Broth of white fungus soup, which is porous sponge and easy to absorb moisture. After discharge, it should be packaged in a low humidity and clean environment as soon as possible, commonly using aluminum foil bags, nitrogen filling, or deoxidizers. If the humidity in the packaging environment is too high, the finished product will quickly regain moisture and become soft. The rehydration property is that the acceptance core is qualified, and the freeze-dried Broth of white fungus soup should be able to rehydrate quickly with hot water to restore the thick, smooth and gelatinous state of the soup. If there is layering, high water output, and insufficient gum after rehydration, it is mostly due to poor control of the boiling, pre freezing, or drying stages.