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WULS-SGGW, Institute of Food Sciences
University of Valencia, Faculty of Pharmacy, Nutrition and Food Science Area
Sorbonne Universites, University of Technology of Compiègne, Integrated Transformations of Renewable Matter Laboratory
Shiraz University of Medical Sciences, Division of Food and Nutrition, Burn and Wound Healing Research Center
Publication date: 2021-06-07
Radish sprouts are rich in bioactive compounds and usually consumed as raw or slightly cooked. Due to their high water activity, they are perishable and the microorganisms can grow very easily. Moreover, sprouts have been associated with numerous foodborne outbreaks worldwide. Thus, there is a need to develop efficient methods to preserve all the healthy valuable compounds and limiting the contamination of sprouts with foodborne pathogens. One of the ideas is to use drying as one of the oldest methods of food preservation. However, the high temperature of traditional drying negatively influences the quality of agricultural products and this process is energy-intensive. The different methods of drying can be used in order to shorten the drying time and improve the quality of dried plant tissue. The aim of this work was to compare the drying kinetics of different drying techniques such as convective drying (air-drying, CD), microwave-assisted convective drying (MV-CD) and infrared-assisted convective drying (IR-CD) of radish sprouts. Convective drying was conducted using temperature of air equal to 60°C and airflow set at 1 m·s –1 . Microwave-assisted convective drying was set on microwave power equal to 200 W, the airflow 1 m·s –1 and the temperature was equal to 30°C. In infrared-assisted convective drying was used the power of infrared emitter equal 7.875 kW·m –2 , and airflow was set at 1 m·s –1 . Fresh radish sprouts contained 88.64% of water and their water activity was equal to 0.94. Drying time was calculated as the time necessary to reach a moisture ratio equal to 0.0014. The shortest drying time (92 min) was noted for the convective drying compared to infrared-assisted (127 min) and microwave-assisted (152 min) air-drying methods. The highest value of drying rate was noticed for the samples dried by the convective method. For microwave-assisted convective drying and infrared-assisted convective drying rates were reduced by 45.2% and 27.6%, respectively. After the drying process, water content was reduced to the range of 4.53–5.65%, whereas water activity was reduced to the range of 0.330–0.401. This means that all of the dried products exhibited water activity below 0.6 which ensures their microbiological stability and improves the safety of radish sprouts.
Figiel A., 2007. Dehydration of apples by a combination of convective and vacuum-microwave drying. Pol. J. Food and Nutr. Sci. 57(4), 131–135.
Horwitz W. (Ed.), 2002. Method 920.15. In: Official Methods of Analysis of AOAC International. 17th ed. AOAC International, Gaithersburg, Md.
Jayaraman K.S., Das Gupta D.K., 2006. Drying of fruits and vegetables. In: A.S. Mujumdar (Ed.), Handbook of Industrial Drying. Taylor & Francis Group, New York, 606–631.
Kowalski S.J., Rajewska K., 2009. Convective drying enhanced with microwave and infrared radiation. Dry. Technol. 27(7), 878–887.
Kucuk H., Midilli A., Kilic A., Dincer I., 2014. A review on thin-layer drying – curve equations. Dry. Technol. 32(7), 757–773.
Lewicki P.P., 2006. Design of hot air drying for better foods. Trends Food Sci. Technol. 17(4), 153–163.
Lewicki P.P., 2010. Kiełki nasion jako źródło cennych składników odżywczych [Sprouts as source of valuable nutrients]. ŻNTJ 73, 18–33.
Li R., Song D., Vriesekoop F., Cheng L., Yuan Q., Liang H., 2016. Glucoraphenin, sulforaphene, and antiproliferative capacity of radish sprouts in germinating and thermal processes. Eur. Food Res. Technol. 243(4), 1–8.
Markowski M., Sobieski W., Konopka I., Tańska M., Białobrzewski I., 2007. Drying characteristics of barley grain dried in a spouted-bed and combined IR-convection dryers. Dry. Technol. 25(10), 1621–1632.
Maskan M., 2001. Drying, shrinkage and rehydration characteristics of kiwifruits during hot air and microwave drying. J. Food Eng. 48(2), 177–182.
Michino H., Araki K., Minami S., Takaya S., Sakai N., Miyazaki M., Ono A., Yanagawa H., 1999. Massive outbreak of Escherichia coli O157:H7 infection in schoolchildren in Sakai City, Japan, associated with consumption of white radish sprouts. Am. J. Epidemiol. 150(8), 787–796.
Midilli A., Kucuk H., Yapar Z., 2002. A new model for single-layer drying. Dry. Technol. 20(7), 1503–1513.
Ndawula J., Kabasa J.D., Byaruhanga Y.B., 2004. Alterations in fruit and vegetable beta-carotene and vitamin C content caused by open-sun drying, visqueen-covered and polyethylene-covered solar-dryers. Afr. Health Sci. 4(2), 125–130.
Nowacka M., Wiktor A., Śledź M., Jurek N., Witrowa-Rajchert D., 2012. Drying of ultrasound pretreated apple and its selected physical properties. J. Food Eng. 113(3), 427–433.
Oliviero T., Verkerk R., Van Boekel M.A.J.S., Dekker M., 2014. Effect of water content and temperature on inactivation kinetics of myrosinase in broccoli (Brassica oleracea var. italica). Food Chem. 163, 197–201.
Pereira N.R., Marsaioli A. Jr., Ahrne L.M., 2007. Effect of microwave power, air velocity and temperature on the final drying of osmotically dehydrated bananas. J. Food Eng. 81(1), 79–87.
Praveen Kumar D.G., Umesh Hebbar H., Sukumar D., Ramesh M., 2005. Infrared and hot-air drying of onions. JFST 29(2), 132–150.
Śledz M., Wiktor A., Nowacka M., Witrowa-Rajchert D., 2017. Drying kinetics, microstructure and antioxidant properties of basil treated by ultrasound. JFST 40(1), 1–13.
Timoumi S., Mihoubi D., Zagrouba F., 2007. Shrinkage, vitamin C degradation and aroma losses during infra-red drying of apple slices. LWT-Food Sci. Technol. 40(9), 1648–1654.
Vega-Galvez A., Ayala-Aponte A., Notte E., Fuente L. de la, Lemus-Mondaca R., 2008. Mathematical modeling of mass transfer during convective dehydration of brown algae Macrocystis pyrifera. Dry. Technol. 26(12), 1610–1616.
Wiktor A., Nowacka M., Śledź M., Selke M., Witrowa-Rajchert D., 2012. Kinetyka suszenia konwekcyjnego wspomaganego ogrzewaniem mikrofalowym miąższu jabłka – dobór modelu matematycznego [Kinetics of microwave-assisted drying of apple – Selection of suitable mathematical model]. Nauki Inż. Technol. 4(7), 99–111.
Zhang C., Cao W., Hung Y.-C., Li B., 2016. Application of electrolyzed oxidizing water in production of radish sprouts to reduce natural microbiota. Food Control 67, 177–182.