Drying Kinetics and Fungal Infection in Red and Yellow Onions (Allium cepa): A Simulation Approach | Chapter 4 | New Horizons of Science, Technology and Culture Vol. 6

 

In the Philippines, red and yellow onions are frequently cultivated. The country’s advantageous climate and soil traits create an optimal setting for growing these onion types. The elevated moisture levels in onions render them vulnerable to fungal growth, especially Aspergillus niger, leading to spoilage and economic losses in agriculture. Drying is a method used to prolong the shelf life of onions by decreasing moisture content and water activity. Dehydrating onions to a moisture content (MC) of 5% prevents the proliferation of microorganisms and ultimately extends their shelf life. This study aims to determine the ideal drying temperature and minimum duration for onions to reach 5% moisture content by assessing the least energy usage. Three mathematical models—Laplace Transform Model, Page Model, and Non-linear Decomposition Model—were analysed to characterise the drying behaviour of thinly cut red and yellow onions at temperatures of 50, 60, and 70°C, utilising a tray dryer with 20% relative humidity and an air velocity of 2 m/s. The Page model provided the optimal fit for red and yellow onions with the smallest overall error. The optimum drying temperature was observed at 70°C for both red and yellow onions, which was efficient in producing quality onions without any fungal growth at the shortest drying time of 25.6 and 24.74 minutes, respectively. The power requirement calculated at 70°C was 154.18 W for red onions and 148.07 W for yellow onions.  These results may serve as a basis for developing efficient drying protocols in red and yellow onion processing industries.

 

 

Author(s) Details

 

Lola Domnina Pestaño
Chemical Engineering Department, Faculty of Engineering, University of Santo Tomas, Philippines and Research Center for the Natural and Applied Sciences, University of Santo Tomas, Philippines.

 

Megan Krisanta E. Gaspar
Chemical Engineering Department, Faculty of Engineering, University of Santo Tomas, Philippines and Research Center for the Natural and Applied Sciences, University of Santo Tomas, Philippines.

 

Aereous Francesca D. Quizon
Chemical Engineering Department, Faculty of Engineering, University of Santo Tomas, Philippines and Research Center for the Natural and Applied Sciences, University of Santo Tomas, Philippines.

 

Rhodelie Anne L. Sandoval
Chemical Engineering Department, Faculty of Engineering, University of Santo Tomas, Philippines and Research Center for the Natural and Applied Sciences, University of Santo Tomas, Philippines.

 

Please see the book here :- https://doi.org/10.9734/bpi/nhstc/v6/6622

The Drying Kinetics of Pre-Treated Sweet Potato Strips | Chapter 1 | Contemporary Perspective on Science, Technology and Research Vol. 6

 Sweet potatoes are prone to the fungi, Rhizopus oryzae that results in fast spoilage upon delivery due to its moisture content (MC). This problem can be addressed by a drying process where a hot tray air dryer was used. The decrease in MC can prolong the shelf-life of the sweet potato. Also, pre-treating sweet potato with sodium metabisulfite results in unique flavor, color and texture attributes which are the main drivers of consumer acceptability of the products.  Sweet potatoes were cut uniformly into 30x5x5 mm dimension. The sweet potato strips were soaked in 2%(w/v) Potassium Metabisulfite (KMS) solution at 50°C for 15 minutes and were drained under standard condition. The treated sweet potato strips were dried at 40°C, 50°C, 60° C until the constant weight was obtained. Laplace Transform Model, Non-Linear Decomposition Model, and Page Model are the three mathematical models that were compared to determine what is the best fit for the drying of the sweet potato. Based on data gathered, The Page model was found to be the most suitable to describe the drying characteristics of treated sweet potato strips with the least total error and highest coefficient of determination. The optimum drying temperature was 60°C with a drying time of 46 minutes to achieve 10% MC that inhibit the growth of Rhizopus oryzae. The pre-treatment of sweet potato strips avoids the undesirable changes such as the natural color and texture of sweet potatoes after air-drying.

Author(s) Details:

Lola Domnina Pestaño,
Department of Chemical Engineering, Faculty of Engineering, University of Santo Tomas, 1015 España Boulevard, Manila-1004, Philippines and Research Center for Natural and Applied Sciences, University of Santo Tomas, 1015 España Boulevard, Manila 1004, Philippines. 

Fauve Ira Alexa V. Obregon,
Department of Chemical Engineering, Faculty of Engineering, University of Santo Tomas, 1015 España Boulevard, Manila-1004, Philippines.

Maria Blesy C. Silvano,
Department of Chemical Engineering, Faculty of Engineering, University of Santo Tomas, 1015 España Boulevard, Manila-1004, Philippines.

Jeelaine G. Vicencio,
Department of Chemical Engineering, Faculty of Engineering, University of Santo Tomas, 1015 España Boulevard, Manila-1004, Philippines.

Please see the link here: https://stm.bookpi.org/CPSTR-V6/article/view/13558