Okara is a byproduct of soymilk processing and is rich in fiber and protein. It is underutilized in the food industry as an ingredient owing to its high perishability. The objective of this work was to study the drying of okara in a rotating-pulsed fluidized bed dryer to verify the effect of air temperature (50–90 °C) and frequency of disc rotation (7.5–24.5 Hz) on the inactivation of trypsin inhibitors and the retention of the total phenolic compounds and isoflavones. The drying process was effective in drying this cohesive material. The process conditions exhibited no significant effect on the activity of trypsin inhibitors and content of total isoflavones. However, the content of total phenolic compounds was affected by the air temperature, in which the higher retention occurred at 70 °C and 16 Hz. Regarding the conversion of isoflavone classes, the drying process favored the hydrolysis of malonylglycosides and β-glycosides into aglycones.
This is a preview of subscription content, access via your institution.
Buy single article
Instant access to the full article PDF.
Tax calculation will be finalised during checkout.
Subscribe to journal
Immediate online access to all issues from 2019. Subscription will auto renew annually.
Tax calculation will be finalised during checkout.
Agrahar-Murugkar, D., & Jha, K. (2010). Effect of drying on nutritional and functional quality and electrophoretic pattern of soyflour from sprouted soybean (Glycine max). Journal of Food Science and Technology, 47(5), 482–487.
Andrade, J. C., Mandarino, J. M. G., Kurozawa, L. E., & Ida, E. I. (2016). The effect of thermal treatment of whole soybean flour on the conversion of isoflavones and inactivation of trypsin inhibitors. Food Chemistry, 194, 1095–1101.
AOAC. (2016). Official methods of analysis (20th ed.). Washington, D.C.: Association of Official Analytical Chemists International.
AOCS. (2009). Sampling and analysis of oilseed by-products. Trypsin inhibitor activity. Champaign: American Oil Chemist’s Society Official Method Ba 12-75.
Barnes, S. (2010). The biochemistry, chemistry and physiology of the isoflavones in soybeans and their food products. Lymphatic Research and Biology, 8(1), 89–98.
Baú, T. R., & Ida, E. I. (2015). Soymilk processing with higher isoflavone aglycone content. Food Chemistry, 183, 161–168.
Bootkote, P., Soponronnarit, S., & Prachayawarakorn, S. (2016). Process of producing parboiled rice with different colors by fluidized bed drying technique including tempering. Food and Bioprocess Technology, 9(9), 1574–1586.
Chien, J. T., Hsieh, H. C., Kao, T. H., & Chen, B. H. (2005). Kinetic model for studying the conversion and degradation of isoflavones during heating. Food Chemistry, 91(3), 425–434.
Chung, I.-M., Seo, S.-H., Ahn, J.-K., & Kim, S.-H. (2011). Effect of processing, fermentation, and aging treatment to content and profile of phenolic compounds in soybean seed, soy curd and soy paste. Food Chemistry, 127(3), 960–967.
Croge, C., Felix, D. S., Araújo, P., & Gallina, M. (2018). Okara residue as source of antioxidants against lipid oxidation in milk enriched with omega-3 and bioavailability of bioactive compounds after in vitro gastrointestinal digestion. Journal of Food Science and Technology, 55, 1518–1524.
Dacanal, G. C., Feltre, G., Thomazi, M. G., & Menegalli, F. C. (2016). Effects of pulsating air flow in fluid bed agglomeration of starch particles. Journal of Food Engineering, 181, 67–83.
Deng, Y., Padilla-Zakour, O., Zhao, Y., & Tao, S. (2015). Boiling on chemical compositions, antinutritional factors, fatty acids, in vitro protein digestibility, and microstructure of buckwheat. Food and Bioprocess Technology, 8(11), 2235–2245.
Dong, X., Xu, W., Sikes, R. A., & Wu, C. (2013). Combination of low dose of genistein and daidzein has synergistic preventive effects on isogenic human prostate cancer cells when compared with individual soy isoflavone. Food Chemistry, 141(3), 1923–1933.
Fennema, O. R. (1996). Water and ice. In O. R. Fennema (Ed.), Food Chemistry (3rd ed., pp. 17–94). Marcel Deckker: New York.
Gaewsondee, T., & Duangkhamchan, W. (2019). A novel process for preparing instant riceberry using fluidized bed drying assisted with swirling compresse-air: Kinetic aspects. Food and Bioprocess Technology, 12(8), 1422–1434.
Grizotto, R. K., & Aguirre, J. M. D. (2011). Study of the flash drying of the residue from soymilk processing - " okara". Food Science and Technology, 31(3), 645–653.
Guimarães, R. M., Silva, T. E., Lemes, A. C., Boldrin, M. C. G., Silva, M. A. P., Silva, F. G., & Egea, M. B. (2018). Okara: A soybean by-product as an alternative to enrich vegetable paste. LWT- Food Science and Technology, 92, 593–599.
Guimarães, R. M., Ida, E. I., Falcão, H. G., Rezende, T. A., Silva, J. S., Alves, C. C. F., Silva, M. A. P., & Egea, M. B. (2020). Evaluating technological quality of okara flours obtained by different drying processes. LWT – Food Science and Technology, in press, 109062.
Handa, C. L., Couto, U. R., Vicensoti, A. H., Georgetti, S. R., & Ida, E. I. (2014). Optimization of soy flour fermentation parameters to produce β-glucosidase for bioconversion into aglycones. Food Chemistry, 152, 56–65.
Hosokawa, M., Katsukawa, M., Tanaka, H., Fukuda, H., Okuno, S., Tsuda, K., & Iritani, N. (2016). Okara ameliorates glucose tolerance in GK rats. Journal of Clinical Biochemistry and Nutrition, 58(3), 216–222.
Itaya, Y., Kobayashi, N., & Nakamiya, T. (2010). Okara drying by pneumatically swirling two-phase flow in entrained bed riser with enlarged zone. Drying Technology, 28(8), 972–980.
Jia, D., Bi, X., Lim, C. J., Sokhansanj, S., & Tsutsumi, A. (2016). Biomass drying in a pulsed fluidized bed without inert bed particles. Fuel, 186, 270–284.
Kakade, M., Rackis, J., McGhee, J., & Puski, G. (1974). Determination of trypsin inhibitor activity of soy products: A collaborative analysis of an improved procedure. Cereal Chemistry, 51, 376–382.
Lima, F. S., & Ida, E. I. (2014). Optimisation of soybean hydrothermal treatment for the conversion of β-glucoside isoflavones to aglycones. LWT- Food Science and Technology, 56(2), 232–239.
Lima, F. S., Handa, C. L., Fernandes, M., Rodrigues, D., Kurozawa, L. E., & Ida, E. I. (2019). Kinetic modeling of the conversion and losses of isoflaones during soybean soaking. Journal of Food Engineering, 261, 171–177.
López, J., Uribe, E., Vega-Gálvez, A., Miranda, M., Vergara, J., Gonzalez, E., & Di Scala, K. (2010). Effect of air temperature on drying kinetics, vitamin C, antioxidant activity, total phenolic content, non-enzymatic browning and firmness of blueberry variety O’Neil. Food and Bioprocess Technology, 3(5), 772–777.
Monteiro, N. E. S., Queirós, L. D., Lopes, D. B., Pedro, A. O., & Macedo, G. A. (2018). Impact of microbiota on the use and effects of isoflavones in the relief of climacteric symptoms in menopausal women – A review. Journal of Functional Foods, 41, 100–111.
Muliterno, M. M., Rodrigues, D., de Lima, F. S., Ida, E. I., & Kurozawa, L. E. (2017). Conversion/degradation of isoflavones and color alterations during the drying of okara. LWT- Food Science and Technology, 75, 512–519.
Nishibori, N., Kishibuchi, R., & Morita, K. (2018). Suppressive effect of okara on intestinal lipid digestion and absorption in mice ingesting high-fat diet. International Journal of Food Sciences and Nutrition, 69(6), 690–695.
Perussello, C. A., Amarante, A. C. C., & Mariani, V. C. (2009). Convective drying kinetics and darkening of okara. Drying Technology, 27(10), 1132–1141.
Rodrigues, M. I., & Iemma, A. F. (2014). Experimental design and process optimization. Boca Raton: CRC Press.
Rosa, G. S., Marsaioli Jr., A., & Rocha, S. C. S. (2013). Energy analysis of poly-hydroxybutirate (PHB) dryign using a combined microwave/rotating pulsed fluidized bed drying (MW/RPFB) dryer. Drying Technology, 31(7), 795–801.
Salim, N. S. M., Garièpy, Y., & Raghavan, V. (2019). Effects of processing on quality atributes of osmo-dried broccoli stalk slices. Food and Bioprocess Technology, 12(7), 1174–1184.
Samborska, K., Jedlińska, A., Wiktor, A., Derewiaka, D., Wołosiak, R., Matwijczuk, A., Jamróz, W., Skwarczyńska-Maj, K., Kiełczewski, D., Błażowski, Ł., Tułodziecki, M., & Witrowa-Rajchert, D. (2019). The effect of low-temperature spray drying with dehumidified air on phenolic compounds, antioxidant activity, and aroma compounds of rapeseed honey powders. Food and Bioprocess Technology, 12(6), 919–932.
Silva, B., Souza, M. M., & Badiale-Furlong, E. (2020). Antioxidant and antifungal activity of phenolic compounds and their relation to aflatoxin B1 occurrence in soybeans. Journal of the Science of Food and Agriculture, 100(3), 1256–1264.
Singh, A., Kuila, A., Yadav, G., & Banerjee, R. (2011). Process optimization for the extraction of polyphenols from okara. Food Technology and Biotechnology, 49, 322–328.
Spagnuolo, C., Russo, G. L., Orhan, I. E., Habtemariam, S., Daglia, M., Sureda, A., Nabavi, S. F., Devi, K. P., Loizzo, M. R., Tundis, R., & Nabavi, S. M. (2015). Genistein and cancer: Current status, challenges, and future directions. Advances in Nutrition, 6(4), 408–419.
Vagadia, B. H., Vanga, S. K., & Raghavan, V. (2017). Inactivation methods of soybean trypsin inhibitor – A review. Trends in Food Science & Technology, 64, 115–125.
Vanga, S. K., Singh, A., & Raghavan, V. (2018). Changes in soybean trypsin inhibitor by varying pressure and temperature of processing: A molecular modeling study. Innovative Food Science & Emerging Technologies, 49, 31–40.
Villanueva-Suárez, M., Pérez-Cózar, M., Mateos-Aparicio, I., & Redondo-Cuenca, A. (2016). Potential fat-lowering and prebiotic effects of enzymatically treated okara in high-cholesterol-fed Wistar rat. International Journal of Food Sciences and Nutrition, 67(7), 828–833.
Villares, A., Rostagno, M. A., García-Lafuente, A., Guillhamón, E., & Martinez, J. A. (2011). Content and profile of isoflavones in soy-based foods as a function of the production process. Food and Bioprocess Technology, 4(1), 27–38.
Wachiraphansakul, S., & Devahastin, S. (2007). Drying kinetics and quality of okara dried in a jet spouted bed of sorbent particles. LWT- Food Science and Technology, 40(2), 207–219.
Walsh, K. A., Kauffman, D. L., Kumar, K. S. V. S., & Neurath, H. (1964). On the structure and function of bovine trypsinogen and trypsin. Proceedings of the National Academy of Sciences of the United States of America, 51, 301–308.
Wang, H. J., & Murphy, P. A. (1994). Isoflavone content in commercial soybean foods. Journal of Agricultural and Food Chemistry, 42(8), 1666–1673.
Wang, G., Deng, Y., Xu, X., He, X., Zhao, Y., Zou, Y., Liu, Z., & Yue, J. (2016). Optimization of air jet impingement drying of okara using response surface methodology. Food Control, 59, 743–749.
Wardhani, D. H., Vázquez, J. A., & Pandiella, S. S. (2008). Kinetics of daidzin and genistin transformations and water absorption during soybean soaking at different temperatures. Food Chemistry, 111(1), 13–19.
Xiao, Y., Zhang, S., Tong, H., & Shi, S. (2018). Comprehensive evaluation of the role of soy and isoflavone supplementation in humans and animals over the past decades. Phytotherapy Research, 32(3), 384–394.
Yoshiara, L. Y., Madeira, T. B., Delaroza, F., Silva, J. B., & Ida, E. I. (2012). Optimization of soy isoflavone extraction with different solvents using the simplex-centroid mixture design. International Journal of Food Sciences and Nutrition, 63(8), 978–986.
The authors acknowledge the São Paulo Research Foundation, FAPESP (17/16835-5) and FAEPEX/Unicamp (14759-17), for the financial support. Lazarin, R.A. would like to thank FAEPEX/Unicamp for the master scholarship (2977/16). Kurozawa, L. is a CNPq Research Fellow.
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Chemical compounds: Daidzein (PubChem CID: 5281708), Daidzin (PubChem CID: 107971), 6”-O-acetyldaidzin (PubChem CID: 156155), 6”-O-malonyldaidzin (PubChem CID: 9913968), Genistein (PubChem CID: 5280961), Genistin (PubChem CID: 5281377), 6"-O-acetylgenistin (PubChem CID: 5315831), 6”-O-malonylgenistin (PubChem CID: 53398685), Glycitein (PubChem CID: 5317750), Glycitin (PubChem CID: 187808), 6”-O-acetylglycitin (PubChem CID: 10228095), malonylglycitin (PubChem CID: 23724657).
About this article
Cite this article
Lazarin, R.A., Falcão, H.G., Ida, E.I. et al. Rotating-Pulsed Fluidized Bed Drying of Okara: Evaluation of Process Kinetic and Nutritive Properties of Dried Product. Food Bioprocess Technol 13, 1611–1620 (2020). https://doi.org/10.1007/s11947-020-02500-2
- Soy pulp
- Rotating-pulsed fluidized bed dryer
- Trypsin inhibitors