Erzincan University Journal of Science and Technology 2149-4584 Erzincan Binali Yıldırım Üniversitesi 10.18185/erzifbed.1202053 Engineering Mühendislik Effect of Different Roasting Methods on Some Properties of Walnut Kernels Effect of Different Roasting Methods on Some Properties of Walnut Kernels https://orcid.org/0000-0002-4075-8823 Kutlu Kantar Naciye BAYBURT UNIVERSITY, AYDINTEPE VOCATIONAL SCHOOL, DEPARTMENT OF FOOD PROCESSING https://orcid.org/0000-0002-8836-8808 Elbir Tuğba BAYBURT UNIVERSITY, FACULTY OF ENGINEERING https://orcid.org/0000-0001-7113-8574 Yılmaz Özlem BAYBURT UNIVERSITY https://orcid.org/0000-0002-6756-0331 Kamiloğlu Aybike BAYBURT UNIVERSITY 12 23 2022 15 Special Issue I 65 74 11 10 2022 12 01 2022 Copyright © 2008, Erzincan Üniversitesi Fen Bilimleri Enstitüsü Dergisi 2008 Erzincan Üniversitesi Fen Bilimleri Enstitüsü Dergisi

In this study, the effects of oven roasting and microwave roasting on some properties of walnut kernels were determined. Roasting methods at different oven temperatures (70, 100, and 130 ºC for one hour) and at different microwave powers (240, 535 and 830 W for 5 min) were applied to samples. Moisture ratio values, total phenolic compound, antioxidant activity, and oil yield of the roasted and unroasted products were discussed. The highest oil yield was determined in the high temperature oven roasting but the microwave roasting mostly increased the oil yield of the product. Microwave roasting was found to be more suitable for decreasing moisture content. The lowest antioxidant activity was detected with microwave roasting. It was determined that the effect on the amount of phenolic substance in the two methods was indifferent.

In this study, the effects of oven roasting and microwave roasting on some properties of walnut kernels were determined. Roasting methods at different oven temperatures (70, 100, and 130 ºC for one hour) and at different microwave powers (240, 535 and 830 W for 5 min) were applied to samples. Moisture ratio values, total phenolic compound, antioxidant activity, and oil yield of the roasted and unroasted products were discussed. The highest oil yield was determined in the high temperature oven roasting but the microwave roasting mostly increased the oil yield of the product. Microwave roasting was found to be more suitable for decreasing moisture content. The lowest antioxidant activity was detected with microwave roasting. It was determined that the effect on the amount of phenolic substance in the two methods was indifferent.

 Roasting microwave Juglans regia L. phenolic compound oil Roasting microwave Juglans regia L. phenolic compound oil This study was presented at the 4th International Conference on Advanced Engineering Technologies. [1] Liu, M., Li, C., Cao, C., Wang, L., Li, X., Che, J., ...and Liu, X., (2021). Walnut fruit processing equipment: academic insights and perspectives. Food Engineering Reviews, 13(4), 822-857. [2] Pycia, K., Kapusta, I., Jaworska, G., Jankowska, A., (2019). Antioxidant properties, profile of polyphenolic compounds and tocopherol content in various walnut (Juglans regia L.) varieties. European Food Research and Technology, 245(3), 607-616. [3] Queirós, C. S., Cardoso, S., Lourenço, A., Ferreira, J., Miranda, I., Lourenço, M. J. V., Pereira, H., (2020). Characterization of walnut, almond, and pine nut shells regarding chemical composition and extract composition. Biomass Conversion and Biorefinery, 10(1), 175-188. [4] https://www.fao.org/faostat/en/#data/QCL. Erişim tarihi 08/11/2022. [5] Martínez, M. L., Labuckas, D. O., Lamarque, A. L., Maestri, D. M., (2010). Walnut (Juglans regia L.): genetic resources, chemistry, by‐products. Journal of the Science of Food and Agriculture, 90(12), 1959-1967. [6] Ros, E., Izquierdo-Pulido, M., Sala-Vila, A., (2018). Beneficial effects of walnut consumption on human health: Role of micronutrients. Current Opinion in Clinical Nutrition & Metabolic Care, 21(6), 498-504. [7] Hayes, D., Angove, M. J., Tucci, J., Dennis, C., (2016). Walnuts (Juglans regia) chemical composition and research in human health. Critical Reviews in Food Science and Nutrition, 56(8), 1231-1241. [8] Ni, Z. J., Zhang, Y. G., Chen, S. X., Thakur, K., Wang, S., Zhang, J. G., ... and Wei, Z. J., (2022). Exploration of walnut components and their association with health effects. Critical Reviews in Food Science and Nutrition, 62(19), 5113-5129. [9] Liu, B., Chang, Y., Sui, X., Wang, R., Liu, Z., Sun, J., Xia, J., (2022). Characterization of Predominant Aroma Components in Raw and Roasted Walnut (Juglans regia L.). Food Analytical Methods, 15(3), 717-727. [10] Małgorzata, W., Konrad, P. M., Zieliński, H., (2016). Effect of roasting time of buckwheat groats on the formation of Maillard reaction products and antioxidant capacity. Food Chemistry, 196, 355-358. [11] Gunel, Z., Torun, M., Sahin‐Nadeem, H., (2020). Sugar, d‐pinitol, volatile composition, and antioxidant activity of carob powder roasted by microwave, hot air, and combined microwave/hot air. Journal of Food Processing and Preservation, 44(4), e14371. [12] Nicoli, M. C., Anese, M., Parpinel, M., (1999). Influence of processing on the antioxidant properties of fruit and vegetables. Trends in Food Science & Technology, 10(3), 94-100. [13] Jeong, S. M., Kim, S. Y., Kim, D. R., Nam, K. C., Ahn, D. U., Lee, S. C., (2004). Effect of seed roasting conditions on the antioxidant activity of defatted sesame meal extracts. Journal of Food Science, 69(5), C377-C381. [14] Lin, J. T., Liu, S. C., Hu, C. C., Shyu, Y. S., Hsu, C. Y., Yang, D. J., (2016). Effects of roasting temperature and duration on fatty acid composition, phenolic composition, Maillard reaction degree and antioxidant attribute of almond (Prunus dulcis) kernel. Food Chemistry, 190, 520-528. [15] Sruthi, N. U., Premjit, Y., Pandiselvam, R., Kothakota, A., Ramesh, S. V., (2021). An overview of conventional and emerging techniques of roasting: Effect on food bioactive signatures. Food Chemistry, 348, 129088. [16] Schoeman, L., Manley, M., (2019). Oven and forced convection continuous tumble (FCCT) Roasting: Effect on physicochemical, structural and functional properties of wheat grain. Food and Bioprocess Technology, 12(1), 166-182. [17] Fahmi, R., Ryland, D., Sopiwnyk, E., Malcolmson, L., Shariati‐Ievari, S., McElrea, A., ... and Aliani, M., (2021). Effect of Revtech thermal processing on volatile organic compounds and chemical characteristics of split yellow pea (Pisum sativum L.) flour. Journal of Food Science, 86(10), 4330-4353. [18] Ceccanti, C., Pellegrini, E., Guidi, L., (2021). Effect of superheated steam and conventional steam roasting on nutraceutical quality of several vegetables. LWT, 149, 112014. [19] Bagheri, H., Kashaninejad, M., Ziaiifar, A. M., Aalami, M., (2016). Novel hybridized infrared-hot air method for roasting of peanut kernels. Innovative Food Science & Emerging Technologies, 37, 106-114. [20] Juhaimi, F. A., Özcan, M. M., Uslu, N., Doğu, S., (2017). Pecan walnut (Carya illinoinensis (Wangenh.) K. Koch) oil quality and phenolic compounds as affected by microwave and conventional roasting. Journal of Food Science and Technology, 54(13), 4436-4441. [21] Labuckas, D. O., Maestri, D. M., Perello, M., Martínez, M. L., Lamarque, A. L., (2008). Phenolics from walnut (Juglans regia L.) kernels: Antioxidant activity and interactions with proteins. Food Chemistry, 107(2), 607-612. [22] Wu, S., Shen, D., Wang, R., Li, Q., Mo, R., Zheng, Y., ... and Liu, Y., (2021). Phenolic profiles and antioxidant activities of free, esterified and bound phenolic compounds in walnut kernel. Food Chemistry, 350, 129217. [23] Bao, J. S., Cai, Y. Z., Sun, M., Wang, G., Corke, H., (2005). Anthocyanins, flavonols, and free radical scavenging activity of chinese bayberry (Myrica rubra) extracts and their color properties and stability. Journal of Agricultural and Food Chemistry, 53(6), 2327–2332. [24] AOAC, C. J. O. M. G., MD, USA. (2005). Official methods of analysis of the Association of Analytical Chemists International. [25] Bagheri, H., Kashaninejad, M., Ziaiifar, A. M., Aalami, M., (2019). Textural, color and sensory attributes of peanut kernels as affected by infrared roasting method. Information Processing in Agriculture, 6(2), 255-264. [26] Shakerardekani, A., Karim, R., Ghazali, H. M., Chin, N. L., (2011). Effect of roasting conditions on hardness, moisture content and colour of pistachio kernels. Moisture Content and Colour of Pistachio Kernels, 18, 704-710. [27] Ahmed, I. A. M., Al Juhaimi, F. Y., Osman, M. A., Al Maiman, S. A., Hassan, A. B., Alqah, H. A., ... and Ghafoor, K., (2020). Effect of oven roasting treatment on the antioxidant activity, phenolic compounds, fatty acids, minerals, and protein profile of Samh (Mesembryanthemum forsskalei Hochst) seeds. LWT, 131, 109825. [28] Vignoli J.A., Viegas M.C., Bassoli D.G., Benassi Md.T., (2014). Roasting process affects differently the bioactive compounds and the antioxidant activity of Arabica and Robusta coffees. Food Res. Int. 61: 279–85 . [29] Herawati, D., Giriwono, P. E., Dewi, F. N. A., Kashiwagi, T., Andarwulan, N., (2019). Critical roasting level determines bioactive content and antioxidant activity of Robusta coffee beans. Food Science and Biotechnology, 28(1), 7-14. [30] Poggetti, L., Ferfuia, C., Chiabà, C., Testolin, R., Baldini, M., (2018). Kernel oil content and oil composition in walnut (Juglans regia L.) accessions from north‐eastern Italy. Journal of the Science of Food and Agriculture, 98(3), 955-962. [31] Chandrasekara, N., Shahidi, F., (2011). Oxidative stability of cashew oils from raw and roasted nuts. Journal of the American Oil Chemists' Society, 88(8), 1197-1202. [32] Fathi-Achachlouei, B., Azadmard-Damirchi, S., Zahedi, Y., Shaddel, R., (2019). Microwave pretreatment as a promising strategy for increment of nutraceutical content and extraction yield of oil from milk thistle seed. Industrial Crops and Products, 128, 527-533.