RU2608727C2 - Method for fast freezing of food products from vegetable raw materials in package - Google Patents

Abstract

FIELD: food industry.

SUBSTANCE: invention relates to food industry, specifically to methods for production and freezing of food products from vegetable raw materials. Method for fast freezing of food products from vegetable raw materials in package comprises placing a vacuum bag with product on metal mesh conveyor of air quick-freezing apparatus, where there is preliminary freezing of top layer of product at a depth of 2–3 mm by forced blowing with ascending air flow. Then, final product freezing on plate for contact freezing, in which there is a refrigerating machine evaporator. On entire path inside device package with product is blown with ascending flow of cold air at a rate of 2 m/s and temperature of minus 30–35 °C for 20–90 minutes.

EFFECT: proposed method for fast freezing of vegetable product shortens duration of freezing, manufacture a frozen product of vegetable raw materials in vacuum package without its damage and de-vacuuming in process of freezing.

1 cl, 1 dwg

Description

The invention relates to the food industry, and in particular to methods of production and freezing of food products from plant materials, mainly fruits and berries.

There is a method of contact freezing, in which the product is in direct contact with the cooling metal surface of the plates or conveyor (see Refrigeration technology of food products: Textbook for high schools; in 3 parts / V.I. Filippov, M.I. Kremenevskaya, V .E. Kutsakova. - Part II. Technological foundations. - St. Petersburg: GIORD, 2008). The temperature gradient between the surface of the product and the cooling medium will be less than with the convection method, and the heat flux density will be greater. A comparison of the two methods shows that when freezing a product on a metal surface, heat is required to be removed 1.4 ... 1.5 times less, energy consumption is 1.3 ... 1.5 times less. However, when freezing a wet product, it freezes firmly enough to the surface of the metal. To separate the product, the metal surface from the coolant side is heated to a positive temperature, as a result, the production process is complicated, energy costs increase, and the temperature of the frozen product increases. Also known is a method of quick freezing of food products of plant origin, in which the raw materials are cleaned, blanched, vacuum packed and frozen in a convective manner (Patent CN 103636745). The method allows to preserve the organoleptic properties of the product and its food safety.

The disadvantage of this method is the high duration of freezing, since the convective method has a low heat transfer coefficient. For a faster freezing process, you can use the contact method, but in this case there will be the possibility of damage to the package when it is separated from the surface after completion of freezing due to freezing of the package. Moisture may be present on the surface of the package, which will freeze to the contact surface. Freezing the bag can damage the package when it comes off the contact surface. For this reason, it is impossible to use the contact method for plant materials in vacuum packaging, which could reduce the duration of freezing of the product compared to the convective method.

The basis of the invention is the task of creating the possibility of rapid freezing of food products from plant materials in the package while maintaining the proper quality of the product.

To solve this problem, freezing of vegetable raw materials in vacuum packaging will include inspection of raw materials, washing, peeling, cutting, blanching, drying, freezing and packaging under vacuum, freezing is carried out after packaging of the product, in which the convective method of freezing is used, which consists in preliminary freezing of the surface 2-3 mm layer due to forced blowing with air, and final freezing on the plate for contact freezing, while all the way to inside the apparatus, the product is blown with an intense air stream at a temperature of minus 30-35 ° C for 20-90 minutes.

The machine-hardware diagram of the process of packing and freezing products from plant materials, mainly fruits and berries, is presented in FIG. one.

The proposed method for the quick freezing of food products from plant materials in a package is to place a vacuum bag with the product on a metal mesh conveyor of an air quick-freezing apparatus, where preliminary freezing is performed due to forced blowing with an upward flow of air (convective freezing). The mesh conveyor is used to prevent freezing of the product bag to the surface, which makes it easy to separate the product. As a result of the movement of the product along the conveyor, part of the moisture located on the bag is carried away by an upward flow of air, as well as constant movement and vibration of the surface of the bag on the conveyor. As a result, the remaining moisture freezes on the surface of the bag and prevents freezing of the bag to the conveyor grid. In addition, the surface layer of the product hardens with a depth of 2-3 mm, due to which the raw materials in the package acquire additional mechanical strength. The final freezing of the product is carried out on the contact freezing plate, in which the evaporator of the refrigeration machine is located. All the way inside the apparatus, the product bag is blown up by an upward flow of cold air at a speed of 2 m / s and a temperature of minus 30-35 ° C for 20-90 minutes, depending on the type of product, its size and weight. Freezing the product in the described way will reduce the duration of freezing compared to the convective method, eliminating the freezing of packages and their damage.

Thus, the proposed invention allows to obtain a quick-frozen product from plant materials in a vacuum package without the possibility of damage and evacuation during freezing, which reliably protects the product from moisture loss and quality indicators. Another advantage is that the freezing described method will reduce the duration of freezing of the product.

Literature

1. Refrigeration technology of food products: Textbook for universities; in 3 parts / V.I. Filippov, M.I. Kremenevskaya, V.E. Kutsakova. - Part II. Technological basis. - SPb .: GIORD, 2008.

2. Patent 103636745 Republic of China, International classification / Method for preventing quick-frozen taro from browning / Li Zhifang; Xu Haixiang; Xu Chunzhong et al., Applicant JIANGSU AGRI ANIMAL HUSBANDRY VOCATIONAL COLLEGE. - No. 201331603097 20131126; application 11/26/2013; publication 03/19/2014.

Claims (1)

A method of quick freezing food of plant origin, including inspection of raw materials, washing, peeling, cutting, blanching, drying, freezing and packaging, characterized in that the packaging of raw materials is carried out under vacuum, freezing is performed after packaging the product, which uses the convective method of freezing, consisting in the preliminary freezing of the surface layer of the product with a depth of 2-3 mm due to forced blowing with air, and the final freeze zhivanie on the plate for a contact freezing, while all the way inside the machine the product is blown intensive air flow at minus 30-35 ° C for 20-90 minutes.

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