Study on the effect of intermittent microwave drying conditions on the bioactive compounds and antioxidant capacity of beetroots
Keywords:intermittent microwave drying, beetroot, betalains, total phenolic, antioxidant capacity
The object of this research was the beetroots prepared by intermittent microwave drying at different conditions. The paper aimed to investigate the influence of intermittent microwave drying conditions (power density, microwave gap ratio and slice thickness) on the bioactive compounds and antioxidant capacity of beetroots. A microwave drying system SAM-255 (CEM Corporation, USA) was used to intermittent microwave drying of fresh beetroots. The effect of different power densities (1.0, 1.5, 2.0, and 2.5 W/g), microwave gap ratios (1, 2, 3, and 4) and slice thicknesses (2, 4, 6, and 8 mm) on the bioactive compounds and antioxidant capacity of beetroots were investigated. Colorimetric methods were used to determine contents of betalains, total phenolic and total flavonoid, and antioxidant capacity of dried beetroots. The ascorbic acid content was determined using 2,6-dichloroindophenol titration method.
Results showed that power density, microwave gap ratio and slice thickness significantly affected the drying time, bioactive compounds and antioxidant capacity of beetroots. The drying time decreased with the increasing of power density, while increased significantly with the growth of slice thickness and microwave gap ratio. The shortest drying time (35.4±2.6 min) of beetroots was occurred at microwave gap ratio of 2. The content of betacyanins was found to be the highest in the dried beetroots with thickness of 2 mm. The beetroots with slice thickness of 2 and 4 mm showed the highest betacyanins content. Moreover, the highest content of ascorbic acid (240.00±2.32 mg/100 g) and total flavonoid (14.52±0.06 mg rutin equivalent (RE)/g) was appeared at power density of 2.0 W/g, while the content of total phenolic to be highest (12.54±0.13 mg gallic acid equivalent (GAE)/g) at slice thickness of 6 mm. For the antioxidant capacity of dried beetroots, the 1,1-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity reached to the highest value of 6.43±0.03 mg trolox equivalent (TE)/g at power density of 2.5 W/g. While the highest values of ferric-reducing antioxidant power (FRAP) (15.47±0.10 mg TE/g) and 2,2′-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging activity (25.31±0.30 mg TE/g) at microwave gap ratio of 2. It was found that ABTS radical scavenging ability and FRAP were related to the presence of reductions including betalains, ascorbic acid, and total flavonoid in beetroots.
The most effective condition for intermittent microwave drying of beetroots were microwave gap ratio of 2, power density of 2.0 W/g, and slice thickness of 4 mm, leads to a better preservation of bioactive compounds and high antioxidant capacity.
Chhikara, N., Kushwaha, K., Sharma, P., Gat, Y., Panghal, A. (2019). Bioactive compounds of beetroot and utilization in food processing industry: A critical review. Food Chemistry, 272, 192–200. doi: http://doi.org/10.1016/j.foodchem.2018.08.022
Clifford, T., Howatson, G., West, D., Stevenson, E. (2015). The Potential Benefits of Red Beetroot Supplementation in Health and Disease. Nutrients, 7 (4), 2801–2822. doi: http://doi.org/10.3390/nu7042801
Fu, Y., Shi, J., Xie, S.-Y., Zhang, T.-Y., Soladoye, O. P., Aluko, R. E. (2020). Red Beetroot Betalains: Perspectives on Extraction, Processing, and Potential Health Benefits. Journal of Agricultural and Food Chemistry, 68 (42), 11595–11611. doi: http://doi.org/10.1021/acs.jafc.0c04241
Paciulli, M., Medina-Meza, I. G., Chiavaro, E., Barbosa-Cánovas, G. V. (2016). Impact of thermal and high pressure processing on quality parameters of beetroot (Beta vulgaris L.). LWT – Food Science and Technology, 68, 98–104. doi: http://doi.org/10.1016/j.lwt.2015.12.029
Nistor, O.-V., Seremet (Ceclu), L., Andronoiu, D. G., Rudi, L., Botez, E. (2017). Influence of different drying methods on the physicochemical properties of red beetroot (Beta vulgaris L. var. Cylindra). Food Chemistry, 236, 59–67. doi: http://doi.org/10.1016/j.foodchem.2017.04.129
Jin, W., Zhang, M., Shi, W. (2018). Evaluation of ultrasound pretreatment and drying methods on selected quality attributes of bitter melon (Momordica charantia L.). Drying Technology, 37 (3), 387–396. doi: http://doi.org/10.1080/07373937.2018.1458735
Alibas, I. (2007). Microwave, air and combined microwave–air-drying parameters of pumpkin slices. LWT – Food Science and Technology, 40 (8), 1445–1451. doi: http://doi.org/10.1016/j.lwt.2006.09.002
Arikan, M. F., Ayhan, Z., Soysal, Y., Esturk, O. (2011). Drying Characteristics and Quality Parameters of Microwave-Dried Grated Carrots. Food and Bioprocess Technology, 5 (8), 3217–3229. doi: http://doi.org/10.1007/s11947-011-0682-8
Junqueira, J. R. de J., Corrêa, J. L. G., Ernesto, D. B. (2017). Microwave, convective, and intermittent microwave-convective drying of pulsed vacuum osmodehydrated pumpkin slices. Journal of Food Processing and Preservation, 41 (6), e13250. doi: http://doi.org/10.1111/jfpp.13250
Vadivambal, R., Jayas, D. S. (2008). Non-uniform Temperature Distribution During Microwave Heating of Food Materials – A Review. Food and Bioprocess Technology, 3 (2), 161–171. doi: http://doi.org/10.1007/s11947-008-0136-0
Wei, Q., Huang, J., Zhang, Z., Lia, D., Liu, C., Xiao, Y. et. al. (2018). Effects of different combined drying methods on drying uniformity and quality of dried taro slices. Drying Technology, 37 (3), 322–330. doi: http://doi.org/10.1080/07373937.2018.1445639
Gunasekaran, S. (1999). Pulsed microwave-vacuum drying of food materials. Drying Technology, 17 (3), 395–412. doi: http://doi.org/10.1080/07373939908917542
Stintzing, F. C., Herbach, K. M., Mosshammer, M. R., Carle, R., Yi, W., Sellappan, S. et. al. (2005). Color, betalain pattern, and antioxidant properties of cactus pear (Opuntia spp.) clones. Journal of Agricultural and Food Chemistry, 53 (2), 442–451. doi: http://doi.org/10.1021/jf048751y
Nguyen, T.-V.-L., Nguyen, Q.-N., Nguyen, P.-B.-D., Tran, B.-L., Huynh, P.-T. (2020). Effects of drying conditions in low‐temperature microwave-assisted drying on bioactive compounds and antioxidant activity of dehydrated bitter melon (Momordica charantia L.). Food Science and Nutrition, 8 (7), 3826–3834. doi: http://doi.org/10.1002/fsn3.1676
Emilio, A. P., Laura, A. de la R., Ryszard, A., Fereidoon, S. (2011). Antioxidant activity of fresh and processed Jalapeño and Serrano peppers. Journal of Agricultural and Food Chemistry, 59 (1), 163–173. doi: http://doi.org/10.1021/jf103434u
De Souza, V. R., Pereira, P. A. P., da Silva, T. L. T., de Oliveira Lima, L. C., Pio, R., Queiroz, F. (2014). Determination of the bioactive compounds, antioxidant activity and chemical composition of Brazilian blackberry, red raspberry, strawberry, blueberry and sweet cherry fruits. Food Chemistry, 156, 362–368. doi: http://doi.org/10.1016/j.foodchem.2014.01.125
Brand-Williams, W., Cuvelier, M. E., Berset, C. (1995). Use of a free radical method to evaluate antioxidant activity. LWT – Food Science and Technology, 28 (1), 25–30. doi: http://doi.org/10.1016/s0023-6438(95)80008-5
Benzie, I. F. F., Strain, J. J. (1996). The Ferric Reducing Ability of Plasma (FRAP) as a Measure of “Antioxidant Power”: The FRAP Assay. Analytical Biochemistry, 239 (1), 70–76. doi: http://doi.org/10.1006/abio.1996.0292
Re, R., Pellegrini, N., Proteggente, A., Pannala, A., Yang, M., Rice-Evans, C. (1999). Antioxidant activity applying an improved ABTS radical cation decolorization assay. Free Radical Biology and Medicine, 26 (9-10), 1231–1237. doi: http://doi.org/10.1016/s0891-5849(98)00315-3
Bing, L., Jun, C., Ai-Guo, F., Yan, L., Qun, Y., Chuan, L., Zhen-Hua, D. (2018). Effects of osmotic dehydration vacuum-microwave drying on the properties of tilapia fillets. Czech Journal of Food Sciences, 36 (2), 169–174. doi: http://doi.org/10.17221/137/2017-cjfs
Horuz, E., Jaafar, H. J., Maskan, M. (2016). Ultrasonication as pretreatment for drying of tomato slices in a hot air–microwave hybrid oven. Drying Technology, 35 (7), 849–859. doi: http://doi.org/10.1080/07373937.2016.1222538
Izli, N., Polat, A. (2019). Effect of convective and microwave methods on drying characteristics, color, rehydration and microstructure properties of ginger. Food Science and Technology (Campinas), 39 (10), 652–659. doi: http://doi.org/10.1590/fst.04518
Dudley, G. B., Richert, R., Stiegman, A. (2015). On the existence of and mechanism for microwave-specific reaction rate enhancement. Chemical Science, 6 (4), 2144–2152. doi: http://doi.org/10.1002/chin.201521253
Mao, L.-C., Pan, X., Que, F., Fang, X.-H. (2005). Antioxidant properties of water and ethanol extracts from hot air-dried and freeze-dried daylily flowers. European Food Research and Technology, 222 (3-4), 236–241. doi: http://doi.org/10.1007/s00217-005-0007-0
Inchuen, S., Narkrugsa, W., Pornchaloempong, P. (2010). Effect of drying methods on chemical composition, color and antioxidant properties of Thai red curry powder. Kasetsart Journal (Nature Science), 44 (1), 142–151. Available at: https://www.researchgate.net/publication/266224049
Figiel, A. (2010). Drying kinetics and quality of beetroots dehydrated by combination of convective and vacuum-microwave methods. Journal of Food Engineering, 98 (4), 461–470. doi: http://doi.org/10.1016/j.jfoodeng.2010.01.029
Zielinska, M., Zielinska, D. (2019). Effects of freezing, convective and microwave-vacuum drying on the content of bioactive compounds and color of cranberries. LWT, 104, 202–209. doi: http://doi.org/10.1016/j.lwt.2019.01.041
Ravichandran, K., Saw, N. M. M. T., Mohdaly, A. A. A., Gabr, A. M. M., Kastell, A., Riedel, H. et. al. (2013). Impact of processing of red beet on betalain content and antioxidant activity. Food Research International, 50 (2), 670–675. doi: http://doi.org/10.1016/j.foodres.2011.07.002
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