Effect of Ultrasound-vacuum Pretreatment on Drying Kinetics and Physical Characteristics of Hot Green Pepper

Document Type : Original Paper


Department of Food Science and Technology, Faculty of Agriculture, Isfahan Branch (Khorasgan), Islamic Azad University, Isfahan, Iran


Hot green pepper (Capsicum annuum) is a commonly used spice , that is highly spoilable due to  high moisture content. Therefore, drying is valuable in order to reduce volume, transportation cost and longer shelf life. For this purpose, using an ultrasound-vacuum bath and a water bath-vacuum (50 and 70 °C), under vacuum condition, until reaching 50% humidity were used as a pre-treatment. Then all samples were dried using microwave (360 w) until reaching 10% final moisture content. The diffusion coefficient of hot green pepper slices was calculated using the Fick diffusion model. Applying ultrasound-vacuum pretreatment caused a decrease of the drying time, and increased the diffusion coefficient and drying speed of the product in the microwave sample compared to other samples significantly (P<0.05). Ultrasonic pretreatment significantly reduced changes in the percentage of size change and browning index and increased the rehydration ratio of the sample significantly (P<0.05). In general, applying ultrasonic as a pre-treatment helps to dry green pepper in microwave conditions and increases the speed of drying in microwave and better maintaining the physical characteristics of the product. Finally, the use of ultrasonic can be a perspective to produce a product with better quality and appearance characteristics and more marketability.


Main Subjects

© 2023, Research Institute of Food Science and Technology. All rights reserved.

This is an open-access article distributed under the terms and conditions of the Creative Commons Attribution 4.0 International (CC-BY 4.0). To view a copy of this license, visit (https://creativecommons.org/licenses/by/4.0/).

Başlar, M., Kılıçlı, M., Toker, O. S., Sağdıç, O., & Arici, M. (2014). Ultrasonic vacuum drying technique as a novel process for shortening the drying period for beef and chicken meats. Innovative Food Science & Emerging Technologies, 26, 182-190. https://doi.org/10.1016/j.ifset.2014.06.008
Bhargava, N., Mor, R. S., Kumar, K., & Sharanagat, V. S. (2021). Advances in application of ultrasound in food processing: A review. Ultrasonics sonochemistry, 70, 105293. https://doi.org/10.1016/j.ultsonch.2020.105293
Bisht, A., Kaur, A., Singh, P., Pranshu, & Alam, F. (2022). A study on the dehydration of vegetables using novel drying techniques. The Pharma Innovation Journal, SP-11(1), 978-989. https://www.thepharmajournal.com/archives/2022/vol11issue1S/PartO/S-11-1-161-142.pdf
Brines, C., Mulet, A., García-Pérez, J. V., Riera, E., & Cárcel, J. A. (2015). Influence of the Ultrasonic Power Applied on Freeze Drying Kinetics. Physics Procedia, 70, 850-853. https://doi.org/10.1016/j.phpro.2015.08.174
Chen, Z.-G., Guo, X.-Y., & Wu, T. (2016). A novel dehydration technique for carrot slices implementing ultrasound and vacuum drying methods. Ultrasonics sonochemistry, 30, 28-34. https://doi.org/10.1016/j.ultsonch.2015.11.026
de la Fuente-Blanco, S., Riera-Franco de Sarabia, E., Acosta-Aparicio, V. M., Blanco-Blanco, A., & Gallego-Juárez, J. A. (2006). Food drying process by power ultrasound. Ultrasonics, 44, e523-e527. https://doi.org/10.1016/j.ultras.2006.05.181
Dehghannya, J., Hosseinlar, S.-H., & Heshmati, M. K. (2018). Multi-stage continuous and intermittent microwave drying of quince fruit coupled with osmotic dehydration and low temperature hot air drying. Innovative Food Science & Emerging Technologies, 45, 132-151. https://doi.org/10.1016/j.ifset.2017.10.007
Dı́az, G. R. z., Martı́nez-Monzó, J., Fito, P., & Chiralt, A. (2003). Modelling of dehydration-rehydration of orange slices in combined microwave/air drying. Innovative Food Science & Emerging Technologies, 4(2), 203-209. https://doi.org/10.1016/S1466-8564(03)00016-X
Feng, H. (2002). Analysis of microwave assisted fluidized-bed drying of particulate product with a simplified heat and mass transfer model. International Communications in Heat and Mass Transfer, 29(8), 1021-1028. https://doi.org/10.1016/S0735-1933(02)00430-X
Guclu, G., Keser, D., Kelebek, H., Keskin, M., Emre Sekerli, Y., Soysal, Y., & Selli, S. (2021). Impact of production and drying methods on the volatile and phenolic characteristics of fresh and powdered sweet red peppers. Food Chemistry, 338, 128129. https://doi.org/10.1016/j.foodchem.2020.128129
Hernández-Pérez, T., Gómez-García, M. D. R., Valverde, M. E., & Paredes-López, O. (2020). Capsicum annuum (hot pepper): An ancient Latin-American crop with outstanding bioactive compounds and nutraceutical potential. A review. Compr Rev Food Sci Food Saf, 19(6), 2972-2993. https://doi.org/10.1111/1541-4337.12634
Huang, D., Men, K., Li, D., Wen, T., Gong, Z., Sunden, B., & Wu, Z. (2020). Application of ultrasound technology in the drying of food products. Ultrasonics sonochemistry, 63, 104950. https://doi.org/10.1016/j.ultsonch.2019.104950
Kowalski, S. J., Mierzwa, D., & Stasiak, M. (2017). Ultrasound-assisted convective drying of apples at different process conditions. Drying Technology, 35(8), 939-947. https://doi.org/10.1080/07373937.2016.1239631
Lewicki, P. P. (2006). Design of hot air drying for better foods. Trends in Food Science & Technology, 17(4), 153-163. https://doi.org/10.1016/j.tifs.2005.10.012
Marques, L. G., Prado, M. M., & Freire, J. T. (2009). Rehydration characteristics of freeze-dried tropical fruits. LWT - Food Science and Technology, 42(7), 1232-1237. https://doi.org/10.1016/j.lwt.2009.02.012
Mayor, L., & Sereno, A. M. (2004). Modelling shrinkage during convective drying of food materials: a review. Journal of Food Engineering, 61(3), 373-386. https://doi.org/10.1016/S0260-8774(03)00144-4
Nourani, M., Hamdami, N., Keramat, J., Moheb, A., & Shahedi, M. (2016). Preparation of a stable nanocomposite phase change material (NCPCM) using sodium stearoyl lactylate (SSL) as the surfactant and evaluation of its stability using image analysis. Renewable Energy, 93, 404-411. https://doi.org/10.1016/j.renene.2016.02.073
Nowacka, M., Wiktor, A., Śledź, M., Jurek, N., & Witrowa-Rajchert, D. (2012). Drying of ultrasound pretreated apple and its selected physical properties. Journal of Food Engineering, 113(3), 427-433. https://doi.org/10.1016/j.jfoodeng.2012.06.013
Orsat, V., Raghavan, G. S. V., & Krishnaswamy, K. (2017). 5 - Microwave technology for food processing: An overview of current and future applications. In M. Regier, K. Knoerzer, & H. Schubert (Eds.), The Microwave Processing of Foods (Second Edition) (pp. 100-116). Woodhead Publishing. https://doi.org/10.1016/B978-0-08-100528-6.00005-X
Ozkan, I. A., Akbudak, B., & Akbudak, N. (2007). Microwave drying characteristics of spinach. Journal of Food Engineering, 78(2), 577-583. https://doi.org/10.1016/j.jfoodeng.2005.10.026
Papageorge, L. M., McFeeters, R. F., & Fleming, H. P. (2003). Factors Influencing Texture Retention of Salt-free, Acidified, Red Bell Peppers during Storage. Journal of Agricultural and Food Chemistry, 51(5), 1460-1463. https://doi.org/10.1021/jf025788e
Paran, I., & van der Knaap, E. (2007). Genetic and molecular regulation of fruit and plant domestication traits in tomato and pepper. Journal of Experimental Botany, 58(14), 3841-3852. https://doi.org/10.1093/jxb/erm257
Prosapio, V., & Norton, I. (2018). Simultaneous application of ultrasounds and firming agents to improve the quality properties of osmotic + freeze-dried foods. Lwt, 96, 402-410. https://doi.org/10.1016/j.lwt.2018.05.068
Ratti, C. (1994). Shrinkage during drying of foodstuffs. Journal of Food Engineering, 23(1), 91-105. https://doi.org/10.1016/0260-8774(94)90125-2
Rodríguez, Ó., Santacatalina, J. V., Simal, S., Garcia-Perez, J. V., Femenia, A., & Rosselló, C. (2014). Influence of power ultrasound application on drying kinetics of apple and its antioxidant and microstructural properties. Journal of Food Engineering, 129, 21-29. https://doi.org/10.1016/j.jfoodeng.2014.01.001
Roshanak, S., Rahimmalek, M., & Goli, S. A. (2016). Evaluation of seven different drying treatments in respect to total flavonoid, phenolic, vitamin C content, chlorophyll, antioxidant activity and color of green tea (Camellia sinensis or C. assamica) leaves. J Food Sci Technol, 53(1), 721-729. https://doi.org/10.1007/s13197-015-2030-x
Senadeera, W., Bhandari, B. R., Young, G., & Wijesinghe, B. (2000). Chapter 6- Physical property changes of fruits and vegetables during hot air drying. In A. S. Mujumdar (Ed.), Drying technology in agriculture and food sciences (pp. 149-166). Science Publishers, USA.
Sette, P., Salvatori, D., & Schebor, C. (2016). Physical and mechanical properties of raspberries subjected to osmotic dehydration and further dehydration by air- and freeze-drying. Food and Bioproducts Processing, 100, 156-171. https://doi.org/10.1016/j.fbp.2016.06.018
Volume 12, Issue 3
December 2023
Pages 305-312
  • Receive Date: 18 September 2022
  • Revise Date: 14 February 2023
  • Accept Date: 15 February 2023