Cryoscopic and microbiological study of the semi­finished product for making a smoothie drink

Abstract

The dynamics of freezing a semi-finished product for making a smoothie drink was investigated. We have chosen, as the subject of present study, a semi-finished product whose production technology included strawberry, dried apple, and oat flakes. By using a low temperature calorimeter, crystallization ranges for the examined semi-finished product, as well as the amount of frozen moisture, which was 68.6 %, were identified. It is established that freezing at −20±2 °C contributes to the complete preservation of the sample, and its further storing at the temperature within such limits ensures its storage over a long period of time. It was also experimentally established that the curves of freezing and defrosting of the sample do not coincide, that is, the character of temperature dependence during freezing and defrosting is different. This testifies to the irreversibility of plant tissue during ice formation and thawing. A reduction in the total microbial contamination over a long refrigeration storing is established, which indicates a negative effect of cold on the viability of microorganisms. The amount of mesophilic-aerobic and optionally anaerobic microorganisms in 30, 60, 90, 180, and 270 days of refrigeration at −18±2 °C is significantly reduced compared to freshly prepared. The amount of yeast and mild fungi also decreases during storage. It is important to comply with sanitary and hygienic standards during production, packaging, storing, and selling, since the complete extinction of the microflora does not occur. The development and active introduction of effective freezing technologies, low temperature storage, and processing of fruits and berries would contribute to solving a task on the balanced nutrition of people, reducing the level of diseases, improving quality of life. In addition, the introduction of such technologies would significantly enlarge the base of local processing industry whose development, in turn, would contribute to the development of agricultural production in a given region. The data obtained data could be applied to determine the rational freezing and defrosting modes for a semi-finished product and would make it possible to extend the assortment of frozen products.