Home :: Academic Members :: News

view:24959   Last Update: 2024-3-8

Simin Hagh Nazari

سیمین حق نظری محمدرضا عظیمی جواد درگاهی
پاستوریزاسیون شیر به روش القایی و تاثیر آن بر کیفیت میکروبیولوژیکی شیر
Milk pasteurization by induction heating and its effect on the microbiological quality of milk
Abstract


Increasing the pasteurizing temperature of contaminated milk in classic method for completing the heating process causes burning the milk layer on pasteurizer and creates thick milk stone. This event in addition to prevents the sufficient transfer of heat, produces carcinogenic compounds, changes in milk color and increases remained microbial load in the milk. Thus, threaten the product's health in the method used in this study (induction heating), electromagnetic current was induced into milk and caused it gets hot faster than classic method. In this research, milk was pasteurized by using an induction heater in 243 different conditions and optimized method was selected for adequate process via a factorial experiment design. In this experiment, the effects of four different factors including: 1) 3 intensities of electricity  transmittance (350, 1000 and 1600 watts), 3 levels of test containers surface (12, 17 and 23 cm), 3 temperatures (72, 75 and 84 °C) and 3 pasteurization time (15, 20 and 30 seconds) were used in three replications. The optimized method was selected respectively in three steps based on 1) the minimum percentage of microbial load, 2) a minimum elapsed time for pasteurization and 3) the lowest energy consumption for pasteurization. Consequently, the results showed that destruction of total bacterial load was 99.5 % in selected induced heating method in comparison to classic method (98.23%). Moreover, Coliform and Escherechia counts in induced heating method have been one tenth to classic method. In induced heating method, milk stone wasn’t produced due to the fast heating.

 

 

Copyright © 2024, University of Zanjan, Zanjan, Iran
master[at]znu.ac.ir