The peculiarities of crystal formation during freezing of broccoli

Abstract

The peculiarities of crystallization during the freezing of the inflorescences broccoli of Parthenon sort, zoned cabbage  in Ukraine, have been researched and analyzed. The mass fraction of moisture and the form of its connection with dry substances in freshly picked cabbage and depending on the methods of pretreatment before freezing were determined: blanching for 3 minutes at a temperature of 85°C and exposition in the 3% salt solution for 20 minutes. It is established that in the general part of moisture prevails osmotically-absorbed. When blanching cabbage, the amount of the colloid-bound moisture is significantly reduced and the amount of osmotic-absorbed increased. It is predefined by partial dеnaturаtion of the protein and by the decline of him to moisture keeping ability. Exposure in solution of NaCl substantially does not influence on the change of forms of the moisture binding. Study of the process of the crystals formation was undertaken by the method of differentially thermal analysis. Analysis of the exothermic processes shows that the optimum temperature for storage of non treating broccoli is –14.5°C, at which crystallization occurs all forms of physical and chemically bonded water, which helps to maximize the preservation of consumer properties of cabbage The inflorescences exposure in the salt solution, compared with the most commonly used blanching operation, also contributes to reducing the energy intensity of the production, as it provides the crystallization of all forms of water at a temperature of –10°C, which is substantially lower than the temperature regulated by the regulatory documents –18°С. A forecast model of the dependence of the crystallization initiation temperature on the mass fraction of moisture has been developed. The use of the presented model will help to manage the process of crystallization to improve the quality of the frozen broccoli cabbage.