Document Type : Original research


1 Food Science and Technology Department, Islamic Azad University, Mako, Iran

2 Institute of Chemical Technologies, Iranian Research Organization of Science and Technology (IROST), Tehran, Iran


Effects of pretreatments (blanching, air-drying, osmotic dehydration and freezing) and process parameters: frying temperature (100, 110 and 120°C) and frying time: (180, 300 and 420 s) at constant vacuum pressure of 70 mbar on some quality characteristics of vacuum fried onion chips (oil uptake, shrinkage, breaking force, and total color difference) were studied. The results showed that frying temperature and frying time at all pretreatments had a significant effect (p ≤ 0.05) on oil uptake and shrinkage, as well as total color difference and breaking force of vacuum fried onion chips. The results demonstrated that the oil uptake, shrinkage and total color difference of the fried onion chips increased, while breaking force decreased with increasing frying temperature and time. The results showed that the different pretreatments before vacuum frying influenced significantly (p ≤ 0.05) the quality characteristics of vacuum fried onion chips. At the same frying temperatures and frying times, the lowest oil uptakes were observed in osmotic dehydrated samples, followed by air-dried and then blanched samples. Freezing pretreated onion samples show the highest o oil uptake (p ≤ 0.05) than other pretreatments. Freezing pretreatment resulted in minimum shrinkage, compared to other pretreatments (p ≤ 0.05) followed by osmotic dehydrated samples. Shrinkage in air drying and blanching pre-treated samples did not differ significantly. Osmotic dehydration pretreated onion samples show less breaking force (p ≤ 0.05) than other pretreatments followed by air-dried pretreated onion samples while blanching and freezing pretreatment resulted in minimum crispiness. At the same temperatures and frying times, the lowest levels of total color difference were observed in blanched samples, followed by osmotic dehydrated and then the air-dried samples.  Freezing pretreated onion samples show the highest levels of total color difference (p ≤ 0.05) than other pretreatments.


Main Subjects

Albertos, I., Martin-Diana, A. B., Sanz, M. A., Barat, J. M., Diez, A. M., Jaime, I., & Rico, D. (2016). Effect of high-pressure processing or freezing technologies as pretreatment in vacuum fried carrot snacks. Innovative Food Science Emerging Technology, 33, 115-122.
Andrés-Bello, A., García-Segovia, P., & Martínez-Monzó, J. (2011). Vacuum Frying: An alternative to obtain high-quality dried products. Food Engineering Reviews3(2), 63-78.
Angie, C., Caro, D., Sandrith, D., Sampayo, P. Diofanor, C., & PiedadMontero, C. (2020). Mass transfer and colour analysis during vacuum frying of colombian coastal carimañola. International Journal of Food Science, 106, 1-11.
AOAC. (1990). Official methods of analysis of the Association of Official Analytical Chemists. 2 vols. 15th ed. Washington, DC.
Assis, F. R., Morais, R. M., & Morais, A. (2017). Osmotic dehydration with sorbitol combined with hot air convective drying of apple cubes. Journal of Food Science and Technology, 54(10), 3152–3160.
Ayustaningwarno, F., Dekker, M., Fogliano, V., & Verkerk, R. (2017). Effect of vacuum frying on quality attributes of fruits. Food Engineering Reviews, 10, 154–164.
Bae, S., Choi, J, Y., Lee, H. J., Kim, J., & Moon, K. D. (2020). The effect of osmotic dehydration pretreatment with sweeteners on the quality of dried aronia berries. The Korean Society of Food Preservation Korean Journal of Food Preservation, 27(4), 468-475.
Belkova, B., Hradecky, J., Hurkova, K., Forstova, V., Vaclavik, L., & Hajslova, J. (2018). Impact of vacuum frying on quality of potato crisps and frying oil. Food Chemistry241, 51-59.
Cruz, G., Cruz-Tirado, J. P., Delgado, K. Guzman, Y. Castro, F., Lindsay Rojas, M., & Linares, G. (2018). Impact of pre-drying and frying time on physical properties and sensorial acceptability of fried potato chips. Journal of Food Science and Technology, 55(1), 138-144.
DasGupta, D. K., Manjunatha, S. S., & Mohan Kumar, B. L. (2003). Development and evaluation of selected dehydrated vegetable curry mixes. Indian Food Packer, 57(2), 62-68.
Diamante, L. M., Savage, G. P., & Vanhanen, L. (2012a). Optimization of vacuum frying of gold kiwifruit slices: application of response surface methodology. International Journal of Food Science and Technology, 47, 518-524.
Diamante, L. M., Savage, G. P., Vanhanen, L., & Ihns, R. (2012b). Effects of maltodextrin level, frying temperature and time on the moisture, oil and beta-carotene contents of vacuum-fried apricot slices. International Journal of Food Science and Technology, 47, 325-331.
Dueik, V., & Bouchon, P. (2011). Vacuum frying as a route to produce novel snacks with desired quality attributes according to new health trends. Journal of Food Science76(2), 188-195.
Fan, L.P., Zhang, M., & Mujumdar, A. (2006). Effect of various pretreatments on the quality of vacuum-fried carrot chips. Drying Technology24(11), 1481-1486.
Fante, L., & Norena C. P. Z. (2012). Enzyme inactivation kinetics and colour changes in garlic (Allium stativum L.) blanched under different conditions. Journal of Food Engineering108, 436-443.
Fathi, M., Mohebbi, M., & Razavi, S. M. A. (2011). Application of fractal theory for prediction of shrinkage of dried kiwifruit using artificial neural network and genetic algorithm. Drying Technology, 29, 918–925.
Garayo, J. & Moreira, R. (2002). Vacuum frying of potato chips. Journal of Food Engineering, 55, 181-191.
García, M. A., Ferrero, C., Bertola, N. C., & Zaritzky, N. E. (2002). Edible coatings from cellulose to reduce oil uptake in fried products. Innovative Food Science & Emerging Technologies3(4), 391-397.
Garcia-Segovia, P., Urbano-Ramos, A. M., Fiszman, S., & Martínez Monzó, J. (2016). Effects of processing conditions on the quality of vacuum fried cassava chips (Manihot esculenta Crantz). LWT-Food Science and Technology69, 515-521.
Hu, J., Zeng, H., Deng, C., Wang, P., Fan, L., Zheng, B., & Zhang, Y. (2019). Optimization of vacuum frying condition for producing silver carp surimi chips. Food Sciences & Nutrition, 7(9), 1-10. 
Kidmose, U., & Martens, H. J. (1999). Changes in texture, microstructure and nutritional quality of carrot slices during blanching and freezing. Journal of the Science of Food and Agriculture79, 1747-1753.
Kothakota, A., Thimmaiah, B., Yadav, K. & Panday, J. (2013). Development of microwave baked potato chips using tomato flavor. Asian Journal of Agriculture and Food Science, 1, 246-260.
Krokida, M. K., Oreopoulou, V., Maroulis, Z. B., & Marinos-Kouris, D. (2001). Effect of pre-drying on quality of French fries. Journal of Food Engineering49(4), 347-354.
Kumar, M., & Babu R. (2007). Effect of frying conditions on quality of fried onion slices. Journal of Food Science and Technology, 44(5), 483-486.
Liberty, T. Z., Dehghannyaba, L., & Ngadia, M. (2019). Effective strategies for reduction of oil content in deep-fat fried foods: A review. Trends in Food Science & Technology, 92, 172-183.
Marrelli, M., Amodeo, V., Statti, G., & Conforti, F. (2018). Biological properties and bioactive components of Allium cepa L.: Focus on potential benefits in the treatment of obesity and related comorbidities. Molecules24(1), 119-131.
Mohsenin, N. N. (1986). Physical properties of plant and animal materials. Second ed., Gordon and Breach Science Publishers, New York.
Moreira, R. G. (2014). Vacuum frying versus conventional frying – An overview. European Journal of Lipid Science and Technology, 116(6), 723-734.
Ndiaye, C., Xu, S. Y., & Wang, Z. (2009). Steam blanching effect on polyphenoloxidase, peroxidase and colour of mango (Mangifera indica L.) slices. Food Chemistry113, 92-95.
Negi, P. S., & Roy, S. K. (2001). The effect of blanching on quality attributes of dehydrated carrots during long-term storage. European Food Research and Technology, 212, 445-448.
Nikzad, N., Ghavami, M., Seyedian-Ardabili, M., Akbari-Adergani, B., & Azizinezhad, R. (2021). Effect of deep-frying process using sesame oil, canola and frying oil on the level of bioactive compounds in onion and potato and assessment of their antioxidant activity. Food Science Technology, 41(3), 1-11.
Oztop, M. H., Sahin, S., & Sumnu, G. (2007). Optimization of microwave frying of potato slices by using Taguchi technique. Journal of Food Engineering, 79(10), 83-91.
Pavkov, I., Radojcin, M., Stamenkovic, Z., Kešelj, K., Tylewicz, U., Sipos, P., Ponjican, O., & Sedlar, A. (2021). Effects of osmotic dehydration on the hot air drying of apricot halves: Drying Kinetics, Mass Transfer, and Shrinkage. Processes, 9(2), 1-22.
Pedreschi, F., & Moyano, P. (2005). Effect of pre-drying on texture and oil uptake of potato chips. LWT- Food Science and Technology38(6), 599-604.
Piyalungka, P., Sadiq, M. B., Assavarachan, R., & Nguyen, L. T. (2019). Effects of osmotic pretreatment and frying conditions on quality and storage stability of vacuum-fried pumpkin chips. International Journal of Food Science and Technology, 54, 2963–2972.
Ramesh Babu, D. (2017). Mathematical modeling of moisture loss, oil uptake and colour kinetics during deep fat frying of onion slices. Engineering & Technology in India, 8(1&2), 39-48.
Ren, A., Pan, S., Li, W. Chen, G. & Duan, X. (2018). Effect of various pretreatments on quality attributes of vacuum-fried shiitake mushroom chips. Journal of Food Quality, 1, 1-7.
Rigi, M., Salehi, E. A., & Ghahremani, H. (2020). Determination of optimum osmotic dehydration as a pretreatment in hot air drying of turnip slices by response surface methodology (RSM). Journal of Research and Innovation in Food Science and Technology, 8(4), 325-340.
Rodriguez, A., Sancho, A. M., Barrio, Y., Rosito, P., & Gozzi, M. S. (2019). Combined drying of Nopal pads (Opuntia ficus‐indica): Optimization of osmotic dehydration as a pretreatment before hot air drying. Journal of Food Process Preservation, 43, 1-9.
Roy, S. S., Taylor, T. A., & Kramer, H. L. (2001). Textural and ultrastructural changes in carrot tissue as affected by blanching and freezing. Journal of Food Science66(1), 176-180.
Salehi, F. (2019). Measurement of central temperature and color changes of onion slices during frying process. Food Technology & Nutrition, 16(4), 71-80.
Shyu, S. L., & Hwang, L. S. (2001). Effects of processing conditions on the quality of vacuum fried apple chips. Food Research Insertional, 34, 133-142.
Shyu, S. L., Hau, L. B., & Hwang, L. S. (2005). Effects of processing conditions on the quality of vacuum‐fried carrot chips. Journal of the Science of Food and Agriculture85(11), 1903-1908.
Sobukola, O. P., Dueik, V., Munoz, L., & Bouchon, P. (2013). Comparison of vacuum and atmospheric deep-fat frying of wheat starch and gluten-based snacks. Food Science and Biotechnology22(1), 177-182.
Song, X., Zhang, M., & Mujumdar, A. (2007). Optimization of vacuum microwave predrying and vacuum frying conditions to produce fried potato chips. Drying Technology25(12), 2027-2034.
Su, Y., Zhang, M., Bhandari, B., & Zhang, W. (2018). Enhancement of water removing and the quality of fried purple-fleshed sweet potato in the vacuum frying by combined power ultrasound and microwave technology. Ultrasonics Sonochemistry, 44, 368-379.
Taiwo, K. A., & Baik, O. D. (2007). Effects of pre-treatments on the shrinkage and textural properties of fried sweet. LWT- Food Science and Technology40(4), 661-668.
Therdthai, N., Wuttijumnong, P., Jangchud, A, & Kusucharid, C. (2007). Optimization of vacuum frying condition for shallot. Kasetsart Journal, 41, 338 – 342.
Turkiewicz, I. P., Wojdyło, A., Tkacz, K., Lech, K., & Nowicka, P. (2020). Osmotic dehydration as a pretreatment modulating the physicochemical and biological properties of the Japanese quince fruit dried by the convective and vacuum-microwave method. Food and Bioprocess Technology, 13, 1801–1816.
Wang, H., Fu, S., & Xie, H. (2018). Effect of hot-water blanching pretreatment on drying characteristics and product qualities for the novel integrated freeze-drying of apple slices. Journal of Food Quality, 5, 1-12.
Wang, Y., Ngadi, M. O., & Adedeji, A. A. (2010). Shrinkage of chicken nuggets during deep-fat frying. International Journal of Food Properties, 13, 404–410.
Wang, L., Zhang, M., Fang, Z., & Xu, B. (2014). Application of intermediate-wave infrared drying in preparation of mushroom chewing tablets. Drying Technology, 32, 1820-1827.
Xiao, H. W., Pan, Z., Deng, L., & Zhang, Q. (2017). Recent developments and trends in thermal blanching – A comprehensive review. Information Processing in Agriculture4(2), 1-22.
Xin, Y., Zhang, M., Xu, B., & Sun, J. (2015). Research trends in selected blanching pretreatments and quick-freezing technologies as applied in fruits and vegetables: A review. International Journal of Refrigeration57, 11-25.
Yoshida, M., Isamu, M., & Chiku, K. (2017). Acrylamide in stir-fried potato and onion for simmered dishes in Japan. Food Safety, 5(2), 54–60.