Evaluating the Effects of Grape Harvest Time and Vacuum Drying on the Physicochemical Properties of White Seedless Quchan Raisin Cultivar

Articles in Press

Document Type : Research Article

Authors

• F. Kiumarsi Darbandi ¹
• Y. Selahvarzi ¹
• B. Abedy ¹
• M. Kamali ¹
• H. Sadrnia ²

¹ Department of Horticulture, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran

² Department of Biosystems Engineering, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran

10.22067/jam.2024.87715.1241

Abstract

Introduction
Various methods have been used to dry grapes. The main purpose is to increase shelf life, produce high-quality dried grapes, and also produce raisins to reduce post-harvest losses. Different methods can be used to dry grapes. Sun drying is the method traditionally used to dry commercial raisins. However, this process is very slow and depends mainly on weather conditions, which can cause microbial and insect contamination in dried fruits and hence, reduce their quality. Recently, advanced vacuum drying techniques have been used in order to increase the amount of water removal and ensure better quality of raisins. Vacuum drying (VD) is a process in which wet materials are dried under subatmospheric pressure. Vacuum pressure reduction increases the mass of water between the fruit and its surroundings, thereby reducing the heat needed for rapid drying. Therefore, vacuum drying is a promising technology for drying grapes and has been used in current works. Preserving the quality of raisins and maintaining their essential nutritional indicators is a vital aspect of effective management strategies aimed at enhancing product quality. This improvement boosts demand for raisins in both domestic and international markets. Finding new methods of drying while maintaining the desired quality and preventing contamination are other factors that determine the quality of raisins. On the other hand, it is very important to determine the right time to harvest grapes according to the climatic conditions of each region and its effect on the quality of raisins. For this purpose, in this study, some quantitative, qualitative, and nutritional indicators related to raisins were compared between the sun-dried and vacuum drying methods for the white Quchan cultivar, evaluating the potential of each method in this field.
Materials and Methods
This research was conducted in 2021-2023 in one of the vineyards of the Quchan region in Iran. Quchan city is located within the geographical coordinates of 36 to 37 degrees north latitude and 58 degrees 10 minutes to 58 degrees 58 minutes east longitude. The relative humidity of this city is 40% in summer, 65% in spring, and 60% in autumn. Based on 10-year statistics, the average annual rainfall in this area is 274 mm. This research project was done in the form of a split plot, based on a randomized complete block design with four replications. Experimental factors include three harvesting times (August 27^th, September 6^th, and 16^th) and four modes of drying (sun drying, and vacuum drying at 60, 70, and 80 °C). Fruits were harvested at three different stages, with time intervals of 10 days from August 27 to September 16, based on the sugar content in the pods and the ratio of total soluble solids (TSS) to titratable acidity (TA). At each harvest time, the grapes were dried in four different ways. In the first method, the grapes were dried traditionally in the open environment and in front of the sunlight. In the second method, the grapes were dried using a vacuum system at three different temperatures of 60, 70, and 80 °C.
Results and Discussion
In general, the interaction of harvesting time and drying method had a significant effect on most of the studied traits. The grape drying methods employed in this research significantly influenced the levels of phenolic compounds, flavonoids, and the antioxidant capacity of the resulting white seedless raisins. The amount of these compounds in sun-dried raisins was lower than the raisins produced using the vacuum drying method. The interaction effect of harvesting time and drying method on the production raisin yield was significant at the 1% probability level. The highest yield was related to the third harvest under the vacuum dryer at 60 °C (305.52 g kg^-1), and the lowest yield was related to the first and second harvests with an average of 270.29 g kg^-1 in the sun-dried method. In general, the highest amount of TSS was related to the treatments of the third harvest, which was observed in vacuum drying at 60 °C. After that, no significant difference was observed in temperatures of 70 and 80 °C. The amount of antioxidant, phenol, flavonoid, and total sugar content in the vacuum drying treatment was higher than the sun drying method. The total soluble sugars in sun-dried raisins were, on average, 22.68% lower compared to those dried using the vacuum method. In terms of total microbial count, the highest microbial load (126.51 Cfu g^-1) was related to sun-dried raisins. The treatments under vacuum drying at all three temperatures of 60, 70, and 80 °C showed the lowest amount of microbial load (almost zero). The low level of microbial contamination in raisins produced by the vacuum method in this research can be attributed to the short drying time and also the lack of contact with the surrounding environment.
Conclusion
Vacuum drying is a new technology that has been developed in recent years, employing a lower pressure in the chamber to increase the moisture transfer during the drying process. In this method, due to the lack of oxygen in the environment, some undesirable biochemical reactions such as browning, oxidation, and degradation reactions are reduced. In addition, the periodic pressure change can create fissured and porous structures in the skin of the sample, thereby increasing the mass transfer through the pores. Overall, the results of this research showed that the raisins produced in the third harvest and using vacuum drying at 60 °C had better quality than other treatments in terms of biochemical and sensory characteristics, including flavor, texture, and color. It can also be concluded that the vacuum drying method is a good alternative to traditional drying methods.

Keywords

• Antioxidant
• Flavonoid
• Microbial load
• Phenol content
• Vacuum dryer

Main Subjects

• Post-harvest technologies

©2025 The author(s). This is an open access article distributed under Creative Commons Attribution 4.0 International License (CC BY 4.0)

References

1. Adiletta, G., Russo, P., Senadeera, W., & Di Matteo, M. (2016). Drying characteristics and quality of grape under physical pretreatment. Journal of Food Engineering. 172, 9-18. https://doi.org/10.1016/j.jfoodeng.2015.06.031
2. Ayoubi, A., Sedaghat, N., Kashaninejad, M., Mohebbi, M., & Nassiri Mahalati, M. (2016). Investigation the effect of cabinet drying conditions and different pretreaMAtments on drying rate of grape and quality of raisin. Iranian Food Science and Technology Research Journal, 226-238. (in Persian). https://doi.org/10.22067/ifstrj.v1395i2.32219
3. Bahmanpour, H., Sajadiye, M., Sheykh davoodi, M. J., & Zolfaghari, M. (2016). The Effect of Temperature and Drying Method on Drying Time and Color Quality of Mint. Journal of Agricultural Machinery, 415-426. (in Persian). https://doi.org/10.22067/jam.v7i2.51268
4. Baloch, M. K., & Bibi, F. (2012). Effect of harvesting and storage conditions on the post harvest quality and shelf life of Mango (Mangifera indica) fruit. South African Journal of Botany, 83, 109-116. https://doi.org/10.1016/j.sajb.2012.08.001
5. Bozkir, H. (2020). Effects of hot air, vacuum infrared, and vacuum microwave dryers on the drying kinetics and quality characteristics of orange slices. Journal of Food Process Engineering, 43(10), e13485.‏ https://doi.org/10.1111/jfpe.13485
6. Busta, F. F., Peterson, E. H., Adams, D. M., & Johnson, M. G. (1984). Colony count methods. Compendium of Methods for the Microbiological Examination of Foods, 2, 62-83.‏
7. Cemeroğlu, B. S. (2011). Meyve ve sebze işleme teknolojisi. Nobel Akademik Yayıncılık.‏
8. 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. https://doi.org/10.38212/2224-6614.2748
9. Chen, P. M., & Mellenthin, W. M. (1981). Effect of harvest date on ripening capacity and post harvest life of Anjou pears. Journal of American Society for Horticultural Science, 106, 38-42. https://doi.org/10.21273/JASHS.106.1.38
10. Chiou, A., Karathanos, V. T., Mylona, A., Salta, F. N., Preventi, F., & Andrikopoulos, N. K. (2007). Currants (Vitis vinifera ) content of simple phenolics and antioxidant activity. Food Chemistry, 102, 516-22. https://doi.org/10.1016/j.foodchem.2006.06.009
11. Chong, C. H., Law, C. L., Figiel, A., Wojdylo, A., & Oziemblowski, M. (2013). Colour, phenolic content and antioxidant capacity of some fruits dehydrated by a combination of different methods. Food Chemistry, 141, 3889-3896. https://doi.org/10.1016/j.foodchem.2013.06.042
12. Chung, H. S., Kim, J. K., Moon, K. D., & Youn, K. S. (2014). Changes in Color Parameters of Corn Kernels during Roasting. Food Science Biotechnology, 23(6), 1829 1835. https://doi.org/10.1007/s10068-014-0250-x
13. Çoklar, H., & Akbulut, M. (2017). Effect of sun, oven and freeze-drying on anthocyanins, phenolic compounds and antioxidant activity of black grape (Ekşikara) (Vitis vinifera ). South African Journal of Enology and Viticulture, 38(2), 264-272.‏ https://doi.org/10.21548/38-2-2127
14. Dai, J. W., Rao, J. Q., Wang, D., Xie, L., Xiao, H. W., Liu, Y. H., & Gao, Z. J. (2015). Process-based drying temperature and humidity integration control enhances drying kinetics of apricot halves. Drying Technology, 33(3), 365-376. https://doi.org/10.1080/07373937.2014.954667
15. Deng, L. Z., Yang, X. H., Mujumdar, A. S., Zhao, J. H., Wang, D., Zhang, Q., ... & Xiao, H. W. (2018). Red pepper (Capsicum annuum ) drying: Effects of different drying methods on drying kinetics, physicochemical properties, antioxidant capacity, and microstructure. Drying Technology, 36(8), 893-907.‏ https://doi.org/10.1080/07373937.2017.1361439
16. Dissa, A. O., Desmorieux, H., Bathiebo, J., & Koulidiati, J. (2008). Convective drying characteristics of Amelie mango (Mangifera Indica cv. ‘Amelie’) with correction for shrinkage. Journal of Food Engineering, 88, 429-43. https://doi.org/10.1016/j.jfoodeng.2008.03.008
17. FAO-OIV. Table and Dried grapes-FAO-OIV Focus 2019. Available online: http://www.fao.org/3/a-i7042e. (accessed on 6 May 2020).
18. Ferreyra, M. R., Vina, S. Z., Mugridge, A., & Chaves, A. R. (2007). Growth and ripening season effects on antioxidant capacity of Strawberry cultivar selva. Scientia Horticulturae, 112, 27-32. https://doi.org/10.1016/j.scienta.2006.12.001
19. Ghodsvali, A., Mohamadi, M., Mohamadi Chianeh, S., & Rashizadeh, S. (2016). An Investigation on the Effect of Harvest Time and Storage on the Quality Properties of Red Grape, the Variety of Fakhri Shahrood. Journal of Crop Production and Processing, 5(18), 1-13. (in Persian). https://doi.org/10.18869/acadpub.jcpp.5.18.1
20. Gholami parshokohi, M., Mohammadi shamami, M., Mohseni, Sh., Mashallah kermani, A., & Abdolalizadeh, E. (2014). Determination of Some Physical Properties of Pistachio Nut and Its Kernel (Qazvini Varieties). Scientific & Recarch Journals Management System, 10(92), 38. (in Persian).
21. Guiné, R. P. F., Almeida, I. C., Correia, A. C., & Gonçalves, F. J. (2015). Evaluation of the physical, chemical and sensory properties of raisins produced from grapes of the cultivar crimson. Journal of Food Measurement and Characterization, 9, 337-346. https://doi.org/10.1007/s11694-015-9241-8
22. Hayat, K., Zhang, X., Chen, H., Xia, S., Jia, C., & Zhong, F. (2010). Liberation and separation of phenolic compounds from citrus mandarin peels by microwave heating and its effect on antioxidant activity. Separation and Purification Technology, 73, 371-376. https://doi.org/10.1016/j.seppur.2010.04.026
23. Hellman, E. (2004). How to Judge Ripeness before Harvest. Presentation at the 2004 Southwest Regional Vine & Wine Conference, Albuquerque, New Mexico, February 27-28, 2004.
24. Irigoyen, J. J., Emerich, D. W., & Sanchez-Diaz, M. (1992) Water stress induced changes in concentrations of proline and total soluble sugars in nodulated alfalfa (Medicago sativa ) plants. Physiologia Plantarum, 84, 55-60. https://doi.org/10.1111/j.1399-3054.1992.tb08764.x
25. Karaman S., Said Toker O. S., Çam M., Hayta M., Mahmut Doğan M., & Kayacier A. (2014). Bioactive and Physicochemical Properties of Persimmon as Affected by Drying Methods Drying Technology: An International Journal. https://doi.org/10.1080/07373937.2013.821480
26. Karimi, R., & Mirzaei, F. (2017). The effect of three drying methods on biophysical and biochemical properties of raisin. Iranian Journal of Horticultural Science, 49(2), 475-491. (in Persian). https://doi.org/10.22059/ijhs.2017.232628.1249
27. Kerdpiboon, S., Kerr, W. L., & Devahastin, S. (2006). Neural network prediction of physical property changes of dried carrot as a function of fractal dimension and moisture content. Food Research International, 39, 1110-1118. https://doi.org/10.1016/j.foodres.2006.07.019
28. Khiari, R., Zemni, H., & Mihoubi, D. (2019). Raisin processing: Physicochemical, nutritional and microbiological quality characteristics as affected by drying process. Food Reviews International, 35(3), 246-298. https://doi.org/10.1080/87559129.2018.1517264
29. Kruge, E., Dietrich, H., Schopplein, E., Rasim, S., & Kurbel, P. (2011). Cultivar, storage conditions andripening effect on physical and chemical quality of red raspbeery fruit. Postharvest Biology and Technology, 60, 31-37. https://doi.org/10.1016/j.postharvbio.2010.12.001
30. Langová, R., Juzl, M., Cwiková, O., & Kos, I. (2020). Effect of different method of drying of five varieties grapes (vitis vinifera ) on the bunch stem on physicochemical, biochemical properties of raisins. Iranian Horticultural Sciences, 49, 475-491. https://doi.org/10.3390/foods9091183
31. Li, Y., Wang, X., Wu, Z., Wan, N., & Yang, M. (2020). Dehydration of hawthorn fruit juices using ultrasound-assisted vacuum drying. Ultrasonics Sonochemistry, 68, 105219.‏ https://doi.org/10.1016/j.ultsonch.2020.105219.
32. Magnoli, C. A., Astroeca, L., Ponsone, M., Combina, G., Palacio, C. A. R., Rose, A. M., & Dalcero, M. (2004). Survey of mycoflora and ochratoxin A in dried vine fruit from Argentina markets. Letters in Applied Microbiology, 39, 326-331. https://doi.org/10.1111/j.1472-765X.2004.01583.x
33. Magwaza, L. S., & Tesfay, S. Z. (2015). A review of destructive and non-destructive methods for determining Avocado fruit maturity. Food Bioprocess Technology, 8(10), 1995-2011. https://doi.org/10.1007/s11947-015-1568-y
34. Mandal, G., & Thakur, A. K. (2015). Preparation of raisin from grapes varietiesgrown in Punjab with different processing treatments. International Journal of BioResource, Environment and Agriculture Science, 1(1), 25-31.
35. Moreno, J., Gonzales, M., Zúñiga, P., Petzold, G., Mella, K., & Muñoz, O. (2016). Ohmic Heating and Pulsed Vacuum Effect on Dehydration Processes and Polyphenol Component Retention of Osmodehydrated Blueberries (cv. Tifblue). Innovative Food Science Emerging Technologies, 36, 112-119. https://doi.org/10.1016/j.ifset.2016.06.005
36. Papoutsis, K., Pristijono, P., Golding, J. B., Stathopoulos, C. E., Bowyer, M. C., Scarlett, C. J., & Vuong, Q. V. (2017). Effect of vacuum‐drying, hot air‐drying and freeze‐drying on polyphenols and antioxidant capacity of lemon (Citrus limon) pomace aqueous extracts. International Journal of Food Science & Technology, 52(4), 880-887.‏ https://doi.org/10.1111/ijfs.13351
37. Parikh, D. (2015). Vacuum Drying: Basics and Application. Chemical Engineering. (New York). 122, 48.
38. Piazzolla, F., Pati, S., Amodio, M. L., & Colelli, G. (2016). Effect of harvest time on table grape quality during on‐vine storage. Journal of the Science of Food and Agriculture, 96(1), 131-139.‏ https://doi.org/10.1002/jsfa.7072
39. Pileh, F., Farokhzad, A., Esmaiili, M., & Dolati Baneh, H. (2015). Effect of harvest time and storage duration on some biochemical attributes of table grape cv ‘Bidaneh Sefid. Journal of Food Research, 25(4), 1-16. (in Persian).
40. Sabanci, S., & Icier, F. (2017). Applicability of ohmic heating assisted vacuum evaporation for concentration of sour cherry juice. Journal of Food Engineering, 212, 262-270.‏ https://doi.org/10.1016/j.jfoodeng.2017.06.004
41. Sawheny, R. L., Pangavhane, D. R., & Sarsavadia, P. N. (1999). Drying kinetics of single layer Thompson Seedless grape under heated ambient air conditions. Drying Technology, 17(1-2), 215-236. https://doi.org/10.1080/07373939908917526
42. Serratosa, M. P., Marquez, A., Lopez-Toledano, A., Medina, M., & Merida, J. (2011). Changes in hydrophilic and lipophilic antioxidant activity in relation to their phenolic composition during the chamber drying of red grapes at a controlled temperature. Journal of Agricultural and Food Chemistry, 59, 1882-1892. https://doi.org/10.1021/jf1042536
43. Shojah, A., Ghasemnejad, M., & Mortazavi, S. N. (2011). The Changes of Antioxidant Capacity and Post Harvest Quality of Thompson navel and Blood Orange Fruits during Storage. Journal of Horticultural Science, 25(2), 147-155. (in Persian). https://doi.org/10.22067/jhorts4.v1390i0.9984
44. Sotiropoulos, T. E. (2008). Performance of the apple (Malus domestica Borkh) cultivar ‘Imperial Double Red Delicious’ grafted on five rootstock. Horticultural Science, 35, 7-11. https://doi.org/10.17221/645-HORTSCI
45. Topalovic, A., & Mikulic–Petkovsek, M. (2010). Changes in sugars, organic acids and phenolics of grape berries of cultivar cardinal during ripening. Journal of Food, Agriculture and Environment, 8(3,4), 223-227.
46. Raisins: World Markets and Trade. (2018). Available online: https://apps.fas.usda.gov/psdonline/circulars/raisins. (accessed on 20 October 2020).
47. 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. https://doi.org/10.1021/jf9801973
48. Wang, J., Law, C. L., Nema, P. K., Zhao, J. H., Liu, Z. L., Deng, L. Z., ... & Xiao, H. W. (2018). Pulsed vacuum drying enhances drying kinetics and quality of lemon slices. Journal of Food Engineering, 224, 129-138. https://doi.org/10.1016/j.jfoodeng.2018.01.002
49. Wang, J., Mu, W. S., Fang, X. M., Mujumdar, A. S., Yang, X. H., Xue, L. Y., ... & Zhang, Q. (2017). Pulsed vacuum drying of Thompson seedless grape: Effects of berry ripeness on physicochemical properties and drying characteristic. Food a Bioproducts Processing, 106, 117-126. https://doi.org/10.1016/j.fbp.2017.09.003
50. Wang, J., Mujumdar, A. S., Mu, W., Feng, J., Zhang, X., Zhang, Q., ... & Xiao, H. W. (2016). Grape drying: Current status and future trends. Grape and Wine Biotechnology, 7, 145-165‏. https://doi.org/10.5772/64662
51. Xie, L., Mujumdar, A. S., Fang, X. M., Wang, J., Dai, J. W., Du, Z. L., Xiao, H. W., Liu, Y. H., & Gao, Z. J. (2017) a. Far-infrared radiation heating assisted pulsed vacuum drying (FIR-PVD) of Wolfberry (Lycium barbarum ): effects on drying kinetics and quality attributes. Food and Bioproducts Processing, 102, 320-331. https://doi.org/10.1016/j.fbp.2017.01.012
52. Yousefi, S., Emam-Djomeh, Z., Mousavi, S. M. A., & Askari, G. R. (2011). Comparing the effects of microwave and conventional heating methods on the evaporation rate and quality attributes of pomegranate (Punica granatum L.) juice concentrate. Food Bioprocess Technology, 5, 1328e1339. https://doi.org/10.1007/s11947-011-0603-x
53. Zhou, X., Li, R., Lyng, J. G., & Wang, S. (2018). Dielectric properties of kiwifruit associated with a combined radio frequency vacuum and osmotic drying. Journal of Food Engineering, 239, 72-82.‏ https://doi.org/10.1016/j.jfoodeng.2018.07.006
54. Zomorodi, Sh., Amir Shaghaghi, F., & Gerami, K. (2022). Modification of the traditional grape drying place using control heating plates and evaluate its energy consumption. Iranian Journal of Food Science and Technology, 127, 1-13. (in Persian). https://doi.org/10.22034/FSCT.19.127.167