Study of the Coefficient Evaporation Resistance of Various Apples and Pears Varieties Growning in the Southern Regions of Kazakhstan

Abstract

Studies have established that various drying periods are observed during the drying process: for example, for apple varieties, the first drying period is 5.45...6.10 hours, and for pear varieties 6.12 ...6.25 hours. The duration of the second drying period for apple varieties is 4.15...3.50 hours, and for pear varieties 4.35...4.48 hours. The analysis of the drying curve showed that the boundary between the periods of constant and falling land velocity, i.e. the critical humidity for apple varieties is on average 27 ± 2.1%, and for pear 30.1 ± 2.5%. An analysis of the kinetics of moisture evaporation shows that in an apple during the first four hours of drying, on average, 2.71 g evaporates, and for the next two hours it decreases monotonically to 2.31 g. The same picture of moisture evaporation dynamics is also observed for pears: for the first four hours, on average, 3.41 g evaporates, and for the next two hours, the evaporation dynamics decreases to 2.78 g. Studies have established that the coefficient of evaporation resistance for apple varieties: Baiterek, Sarkyt and Saya is µ = 2.03 ± 0.07, for pear varieties: Sylyk, Zhazdyk and Nagima is µ = 2.3± 0.05.

Keywords

• vacuum drying
• apples
• pear
• water activity indicator