Packaging and quick freezing technology of the hot

Packaging and quick freezing technology of Agaricus bisporus (Part 2)

3. Scalding. The main purpose of mushroom scalding is to destroy the activity of polyphenol oxidase, inhibit enzymatic browning, drive away the air in mushroom tissue, shrink the tissue, ensure the requirements of solids, increase elasticity, reduce brittleness, and facilitate packaging. When sulfite is used to protect the color, scalding can also play the role of desulfurization. In order to reduce non enzymatic browning, an appropriate amount of citric acid is often added to the scalding solution to increase the reducibility of the scalding solution and improve the mushroom color

there are two scalding methods: hot water or steam. The steam method has a rich flavor due to less loss of soluble components. The temperature of hot water is ℃, and the ratio of water to mushroom should be greater than 3:2. Under normal circumstances, mushrooms turn from white to light yellow after scalding, which is the reason for non enzymatic browning. With the extension of scalding time, the color is darker and the weight loss is more. Generally, 0.1% citric acid solution is added to the scalding water to adjust the acidity to inhibit non enzymatic browning. The scalding time is controlled within min according to the size of the cap. However, the scalding time should not be too long to prevent the tissue from getting too old, losing water and losing elasticity. In order to prevent the color of mushrooms from darkening, the acidity of scalding solution should be adjusted frequently and the scalding water should be changed regularly

4. Cooling. After scalding, quickly send the mushrooms into the cooling pool to cool thoroughly, so as not to affect the quality by excessive heating. Cooling water contains residual chlorine 0 7mg/kg。

5. Drain. Mushrooms should be drained before quick freezing. Otherwise, the mushroom surface will freeze if it contains too much water, especially for some hydraulic molding machines operating outdoors, the equipment environment is very despicable and clumsy, which is not conducive to packaging and affects the appearance. Moreover, too much water will increase the freezing load. The dewatering can be carried out by vibrating screen, dryer (centrifuge) or fluidized bed precooling device

anjianeng released a new type of open-hole sprayed foam insulation material product 6. Quick freezing. The biggest damage of freezing vegetables is tissue damage. This is mainly due to the expansion of the volume after the formation of ice crystals, while the solid components in vegetables shrink, causing local pressure, leading to the rupture of the cell wall of vegetables and the destruction of their organizational structure, cell dehydration, irreversible changes in the structure of proteins and colloids. The water generated during thawing cannot be combined with proteins to restore their original state, and can only be allowed to flow out. The loss with water also includes water-soluble proteins, vitamins, organic acids, pigments Sugars, inorganic salts and other nutrients. In order to minimize the impact of ice crystals on the quality of vegetables, rapid freezing can be used to make the ice crystal particles in quick-frozen vegetables small and evenly distributed in the cell tissue, so as to reduce the recombination of ice crystals and the local pressure and dehydration damage of ice crystals to cells

fluidized bed quick freezing device should be used for quick freezing of mushrooms. Put the cooled and drained mushrooms evenly on the fluidized bed conveyor belt. Because mushrooms can only form a semi fluidized state in the fluidized bed, the thickness of the mushroom layer of the conveyor belt is cm, the air temperature in the fluidized bed device is required to be -30 to -35 ℃, the flow rate of cold air is m/s, the quick freezing time is min, and the central temperature of mushrooms is below -18 ℃

II. Grading

mushrooms after quick freezing should be graded by roller classifier or mechanical shock drum classifier according to the shape and size of cap and the length of stalk

III. check

remove mushrooms that do not meet the standard requirements of quick-frozen mushrooms: such as deformities, spots, rust, hollowness, handle removal, umbrella opening, color changing mushrooms, thin mushrooms, etc

IV. pack ice clothes

in order to ensure the quality of quick-frozen mushrooms and prevent the dry consumption and oxidation discoloration of products in the market during the refrigeration process, mushrooms must be wrapped in ice after grading and checking. The ice coating has certain technicality, which means that the product should be covered with a layer of thin ice without thawing or caking. The specific method is to pour 5kg mushrooms into perforated plastic baskets or stainless steel wire baskets, then immerse them in clean water at ℃ for s, take them out, vibrate them left and right, shake them evenly and drain them, and operate again. The cooling water shall be clean and contain 0% residual chlorine 7mg/kg。

v. packaging

the packaging must be carried out in a low temperature environment below -5 ℃. When the temperature is above -1 to -4 ℃, the quick-frozen mushroom will recrystallize, which will greatly reduce the quality of the quick-frozen mushroom. The packaging room must be sterilized with UV lamp 1H before packaging, and all packaging tools, working clothes, hats, shoes and hands of workers must be disinfected regularly

the inner package can be used with low temperature resistance, low air permeability, impermeable, odorless, non-toxic, thickness of 0 08mm polyethylene film bag. The outer packing carton has a net weight of 10kg per carton. The surface of the carton must be oiled with good moisture resistance, lined with clean wax paper, and sealed with adhesive tape paper. All packaging materials must be pre cooled at a low temperature below -10 ℃ before packaging

quick frozen mushrooms should be checked according to the specification before packaging. When sealing the bag manually, pay attention to expelling air to prevent oxidation. If it is possible to seal bags with a heat sealing machine, here is an important feature of high molecules --- creep vacuum packaging machine bagging. Weigh the whole box after packing. The qualified person shall print the product name, specification, weight, production date, storage condition and period, batch number and manufacturer on the carton. After sealing the box with sealing strip, it shall be stored in the refrigerator immediately

VI. cold storage

quickly put the quick-frozen mushrooms that meet the quality standards after inspection into the refrigerator for refrigeration. The refrigeration temperature is -18 to -20 ℃, and the temperature fluctuation range should be as small as possible, generally controlled within ± 1 ℃. Quick frozen mushrooms should be placed in a special warehouse for storing quick-frozen vegetables. Refrigerate for months at this temperature

source: China Agriculture