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In this work, slices of yellow onions (Allium cape) with a diameter of (6.7 ± 0.05) cm and a thickness of (1 ± 0.05) cm are dehydrated in a drying oven at two temperatures: 40 °C and 90 °C. The average initial mass and water content of the samples are 32.61 g and 92.13%, respectively. The microbial flora in moulds and yeast is also enumerated before and after drying. An experiment plan of two variables, namely drying time and temperature, is followed to optimize the process tests. The moisture content is taken as a response. The interactions between operating variables are shown and a mathematical model is established expressing, thus, the variation of the moisture content of the onion slices as a function of the temperature and the drying time. A correlation of experimental results and calculations is indeed established. The results show that drying duration decreases with increa- sing temperature and water content of onion slices decreases from 92.13% to 4.5% during 2595 minutes, and from 92.13% to 9.47% during 1245 minutes, at 40 °C and 90 °C, respec- tively. Also, the experimental results lead to the appropriate choice of the temperature and the drying time in order to reach adequate moisture content. Finally, Oven drying of the yellow onions with determined dimensions eliminates the moulds to desired and encou- raging values.
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