Condensed milk is produced by evaporation of part of water from fresh milk and by adding sugar. Canning is based on the principle of osmoanabiosis and is achieved by increasing the concentration of solids of milk and by adding sucrose to increase osmotic pressure. The effect of canning is also achieved by heat treatment and integrity of packing.

The composition according to the standard, %:

  • water - 26.5...25.8;
  • fat - 8.5-8.8;
  • mass fraction of solids 29-29.5;
  • protein - 8.8-8.9;
  • lactose - 11.6-11.8;
  • sucrose - 43.5-44.8.

 

The main operations of the conventional technology:

  • Acceptance and quality assessment, cooling, short-time storage, milk purification.
  • Milk standardization by fat and solids. (To increase the fat content, whole milk is standardized by adding cream or milk fat; to reduce the fat content of whole milk - skim milk is added).
  • Pasteurization. (High-temperature pasteurization at temperature of 90-95°C ensures elimination of pathogenic microorganisms and stabilizes physical and chemical properties of milk and as a result milk thickening may be prevented at storage).
  • Cooling to 70-75 °C.
  • Intermediate storage prior to condensation.
  • Addition of sugar. (It is added in solid form or in the form of syrup with sugar content of 60-70%. The resulting syrup is heated up to 95-99°C (without ageing). Syrup is filtered before adding to milk. Most often syrup is added prior to condensation by mixing or in flow).
  • Milk condensation in evaporator. (The readiness of the product is determined by the solids content with refractometer or by density).
  • Cooling of the condensed milk to 20°C within 20-25 minutes. (In crystallizers, in the vacuum environment and continuous mechanical effect - to prevent the formation of large crystals of lactose that leads to the formation of sandiness defect).
  • Addition of seed – lactose ground to ash. (The goal is creation of many centers of lactose crystallization that prevent the formation of large crystals).
  • Packing and storage: in cans - shelf life is 1 year; polypropylene or polystyrene cups and other small packing used in the dairy industry - shelf life is 3 months.

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