The purpose of the paper is to provide practical information on the selection of heat treatment conditions and the prevention of secondary microbial contamination of liquid sugar. The guidelines included in the paper were formulated on the basis of practical experience gained. The most important aspect often refers to the unnoticed cause of secondary contamination of liquid sugar after heat treatment, during its cooling in diaphragm heat exchangers along with the indication of the possibility of elimination of this cause. The article also presents the results of microbiological analysis in the field of heat resistance of microorganisms present in raw juice, obtained from the extractor. The data indicate the difficulty of thermal inactivation of mesophilic and thermophilic spores present in the studied environment. The cited results of microbiological analysis prove the usefulness of the measures to prevent secondary microbial contamination of the finished product.

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The main aim of this paper is to discuss the current state of knowledge on the chemical composition of floc isolated from acidified sugar solutions and explain the mechanism of its formation. The literature data shows that depending on the raw material used for the production of white sugar, i.e. sugar beet and sugarcane, the chemical composition of floc is different. The presence of polysaccharides i.e. dextran or levan in floc is a consequence of microbial activity. Therefore, it cannot be explicitly assumed that the origin of individual ingredients of floc is only the raw material, i.e. beets or sugarcane. Taking into account the literature data concerning the chemical composition of floc, it seems reasonable to link the direct impact of microbial biofilms present in sugar industry installations to the tendency of the final product to create floc. Currently, the basis for assessment of the proneness of sugar to create floc is the result of a 10-day test (ICUMSA Method GS2/3-40A). From the perspective of both producers and consumers of sugar, there is a need to develop and validate quick methods for assessing the tendency of sugar to create floc. This task is only possible to complete, when the mechanism of floc formation is fully explained.

Due to the prolongation of the period of the sugar campaign, it is necessary to optimize the storage conditions, so that changes in the quality of the raw material could be minimized. The aim of this study was to determine the effect of storage duration and temperature on changes in the composition of sugar beet. The study presents the changes in the content of glucose, fructose, raffinose, lactic and acetic acids, nitrates and nitrites as well as in the content of the total number of mesophilic bacteria, denitrifying bacteria and spores of denitrifying bacteria during storage under various conditions.