The effect of three drying methods on biophysical and biochemical properties of raisin

Document Type : Full Paper


1 Assistance Professor, Faculty of Agriculture, Malayer University, Iran

2 Member of Production and Genetic Improvement Department, Iranian Grape and Raisin Institute, Malayer University, Iran

3 Former M. Sc. Student, Faculty of Agriculture, Malayer University, Iran


Raisin is the main product of grape in Iran that obtains through drying process. Regarding to mass production of grape in this country, optimization of the raisin preparation methods in order to increase world market demand is required. In this research, effects of three different methods of drying including of sun drying, shad drying and alkaline emulsion drying (potassium carbonate + ethyl oleate) were investigated on biophysical and biochemical properties' of Sultana grape's raisin including raisins yield, drying rate, dry weight, and rachis weight and also antioxidant capacity (based on DPPH, FRAR methods), total flavonoids, total phenols, total protein, soluble sugars (fructose, glucose, sucrose, raffinose), organic acids (ascorbic acid, malic acid, tartaric acid) and some nutrients under a completely randomized design with three replicates in Iranian Grape and Raisin Institute of Malayer University. In early Sep. of 2015, fruits were harvested manually based on TSS index of 21 (°Brix) and then were laid on drying net racks until they reached 15% moisture. Based on results, significant differences were found among three drying methods regarding to both biophysical and biochemical properties'. The highest drying period was related to shade drying methods while the lowest was found in alkaline emulsion drying method. Furthermore, the highest and lowest grape to raisin drying rate was belonged to alkaline emulsion and shade drying methods, respectively. Raisin yield was highest in alkaline emulsion drying method and lowest in sun drying method. The highest total phenol, total flavonoid and measured antioxidant capacity by DPPH and FRAR was found to be higher in alkaline emulsion drying method compared to other methods. Moreover, soluble sugars (sucrose, glucose, fructose and raffinose) and organic acids (tartaric, malic but not ascorbic acid) was higher in alkaline emulsion drying method than other methods. In conclusion, owing to faster grape to raisin drying rate observed in alkaline emulsion drying method, the oxidation of phenolic compounds and flavonoids of these raisins was lower compared to both sun-and shade drying methods which showed higher nutritional value and antioxidant capacity than other methods.


Main Subjects

  1. Agulea, J. M., Opperman, K. & Sanchez, F. (1987). Kinetic of browning of Sultana grapes. Journal of Food Science, 52, 990-1005.
  2. Almeida, I., Guiné1, R. P. F., Gonçalves, F. & Correia A. C. (2013). Comparison of drying processes for the production of raisins from a seedless variety of grapes. International Conference on Engineering UBI2013 - 27-29 Nov 2013 – University of Beira Interior – Covilhã, Portugal.
  3. Arzani, K., Sherafaty, A. H. & Koushesh-Saba M. (2009). Harvest date and post harvest alkaline treatment effects on quantity and quality of Kashmar, Iran, green raisin. Journal of Agricultural Science and Technology, 11, 449-456.
  4. Aung, L. H., Ramming, D. W. & Tarailo, R. (2002). Changes in moisture, dry matter and soluble sugars of dry-on-the-vine raisins with special reference to sorbitol. The Journal of Horticultural Science and Biotechnology, 77, 1, 100-105
  5. Benzie, I. F. & Strain, J. J. (1996). The ferric reducing ability of plasma (FRAP) as a measure of “antioxidant power”: The FRAP assay. Analytical Biochemistry, 239, 70-76.
  6. Carranza, J., Benlloch, M., Camacho, M. M. & Martínez-Navarrete, N. (2012). Effects of drying and pretreatment on the nutritional and functional quality of raisins. Food and Bioproducts Processing, 90, 243-248.
  7. Carughi, A. (2009). Health benefits of sun-dried raisins, health research and studies center: Kingsburg, CA, USA.
  8. Cetin, E. S., Altinoz, D., Tarcan, E. & Baydar, N. G. (2011). Chemical composition of grape canes. Industrial Crops Andproduction, 34, 994-998
  9. Chang, C., Yang, M., Wen, H. & Chern, J. (2002). Estimation of total flavonoid content in propolis by two complementary colorimetric methods. Journal of Food and Drug Analysis, 10, 178-182.
  10. Comis, D. B., Tamayo, D. M. & Alonso, J. M. (2001). Determination of monosacharids in cider by reversed-phase Liqueid Chromatography. Analytic Chemica Acta, 436, 173-178.
  11. Costa, E., Cosme, F., Jordão, A. M. & Mendes-Faia, A. (2014). Anthocyanin profile and antioxidant activity from 24 grapevarieties cultivated in two Portuguese wine regions. Journal International des Sciences de la Vigne et du Vin, 48, 51-62.
  12. Dincer, L. (1996). Sun drying of sultana grapes, Drying Technology: An International Journal, 14, 1827-1838.
  13. Doymaz, I. & Pala, M. (2002). The effects of dipping pretreatments on air-drying of the seedless grapes. Journal of Food Engineering, 52,413-417.
  14. Eissen, W., Muehlbauer, W. & Kutzbach, H. D. (1985). Solar drying of grape. Drying Technology, 3, 63-74.
  15. Fennema, O. (1993). Química de los alimentos, Editorial Acribia, S. A. Zaragoza, 102-108.
  16. Food and Agriculture Organization. (2014). Statistical Yearbook. FAOSTAT, United Nations New York.
  17. Franco, M., Peinado, R. A., Medina, M. & Moreno, J. (2004). Off-vine grape drying effect on volatile compounds and aromatic series in must from Pedro Ximénez grape variety. Journal of Agriculture and Food Chemistry, 52, 3905-3910.
  18. Gabas, A. L., Menegalli, F. C. & Telis-Romero, J. (1999). Effect of chemical pretreatment on the physical properties of dehydrated grapes. Drying Technology, 17, 1215-1226.
  19. Ghorbani, P., Sarikhani, H., Gholami, M. & Ahmadi, E. (2014). Effect of alkaline treatment on color, phenolic composition and antioxidant property of raisin. Journal of Crop Production and Processing, 4, 63-71. (in Farsi)
  20. Hamada, A. M. & El-Enany, A. E. (1994). Effect of NaCl salinity on growth, pigment and mineral element contents, and gas exchange of broad bean and pea plants. Biologia Plantarum, 36, 75-81.
  21. Isci, B. & Altındisli, A. (2015). Drying of Vitis vinifera L. cv “Sultanina” in tunnel solar drier. Bio Web of Conferences, 5, 01016
  22. Lewis, W, J. & Simmons, L. D. (1978). A test for skin damage of dried grapes. Food Technology in Australia, 30, 391-2.
  23. Lokhande S. M. & Sahoo A. K. (2016). Effect of drying on grape raisin quality parameters. International Journal of Innovation Research in Science and Engineering, 2, 86-95.
  24. Maghsoudi, S. (2012). Food drying technology. Iran agriculture science publishing Co. 330 p. (in Farsi)
  25. Mandal, G.  & Thakur, A. K. (2015). Preparation of raisin from grapes varieties grown in Punjab with different processing treatments. International Journal of Agricultural and Biological Engineering, 1, 25-31.
  26. Miranda, M., Vega-Gálveza, A., López, J., Parada, G., Sanders, M., Aranda, M., Uribe, E. & Di Scala, K. (2010). Impact of air-drying temperature on nutritional properties, total phenolic content and antioxidant capacity of quinoa seeds (Chenopodium quinoa Willd). Industrial Crops and Products, 32, 258-263.
  27. Nejatian, M. N. (2013). A complete guide of grape production and processing. Education and Extention of Agriculture Publishing Co. 319 p. (in Farsi)
  28. Pahlavanzadeh, H., Basiri, A. & Zarrabi, M. (2001). Determination of parameters and pretreatment solution for grape drying. Drying Technology, 19, 217-226.
  29. Pangavhane, D. R., Sawhney, R. L. & Sarsavadia, P. N. (1999). Effect of various dipping pretreatment on drying kinetics of Thompson seedless grapes. Journal of Food Engineering, 39, 211-216.
  30. Parker, T. L., Wang, X. H., Pazmiño, J. & Engeseth, N. J. (2007). Antioxidant capacity and phenolic content of grapes, sun-dried raisins, and golden raisins and their effect on ex vivo serum antioxidant capacity. Journal of Agriculture and Food Chemistry, 55, 8472-8477.
  31. Pellegrini, M., Serafini, S. & Salvatore, D. (2006). Total antioxidant capacity of spices, dried fruits, nuts, pulses, cereals and sweets consumed in Italy assessed by three different in vitro assays. Molecular Nutrition and Food Research, 50, 1030-1038.
  32. Sanchez, C., Larrauri, J. A. & Saura-Calixto, F. A. (1998). Procedure to measure the antiradical efficiency of polyphenols. Journal of the Science of Food and Agriculture, 76, 270-276.
  33. Sanz, M., Castillo, M. D., Corio, N. & Olana, A. (2001). Formation of Amadori compounds in dehydrated fruits. Journal of Agricultural and Food Chemistry, 49, 5228-5231.
  34. Sério, S., Rivero-Pèrez, M. D., Correia, A. C., Jordao, A. M. & Gonzàlez-San Josè, M. L. (2014). Analysis of commercial grape raisins: Phenolic content, antioxidant capacity and radical scavenger activity. Ciência e Técnica Vitivinícola, 29, 1-8.
  35. Shin, K. S., Chakrabarty, D. & Paek, K. Y. (2002). Sprouting rate, change of carbohydrate contents and related enzymes during cold treatment of Lily bulblets regenerated in vitro.Scientia Horticulturae, 96, 195-204
  36. Soysal, Y. M. (2004). Microwave drying characteristics of parsley. Biosystems Engineering, 89, 167-73.
  37. Spiller, G. A. & Spiller, M. (2001). Tartaric acid content of foods. In dietary fiber in human nutrition, p. 681 [GA Spiller, editor]. Boca Raton, FL: CRC Press.
  38. Telis, V. R. N., Lourencon, V. A., Gabas, A. L. & Telis-Romero, J. (2006). Drying rates of rubi grapes submitted to chemical pretreatments for raisin production. Pesquisa Agropecuária Brasileira, 41, 503-509.
  39. Vazquez, G., Chenlo, F., Moreira, R. & Costoyas, A. (2000). Effects of various treatments on the drying kinetics of Muscatel grapes. Drying Technology, 18, 2131-2144.
  40. Velioglu, Y. S., Mazza, G., Gao, L. & Oomah, B. D. (1998). Antioxidant activity and total phenolics in selected fruits, vegetables and grain products. Journal of Agriculture and Food Chemistry, 46, 4113-4117.
  41. Vermerris, W. & Nicholson, R. (2006). Phenolic Compound Biochemistry. Springer Pub., USA.
  42. Vikram, V. B., Ramesh, M. N. & Prapulla, S. G. (2005). Thermal degradation kinetics of nutrients in orange juice heated by electromagnetic and conventional methods. Journal of Food Engineering, 69, 31-40.
  43. Zarei, M., Baninasab, B., Ramin, A. A. & Pirmoradian, M. (2013). The effect of chemical thinning on seasonal changes of mineral nutrient concentrations in leaves and fruits of ‘Soltani’ apple tree. Iran Agricultural Research,32, 89-100.