Document Type : Research Article


Department, Khorasan Razavi Agricultural and Natural Resources Research and Education Center, AREEO, Mashhad, Iran.


Introduction: Saffron (Crocus sativus) is the most expensive kind of spice in the world while around 400 tons of saffron are estimated to be produced in the current Iranian year (March 2016-17) from 90,000 hectares of land under saffron cultivation across the country. But, high share of producing saffron is exclusively dedicated to produce and dry saffron stigma as whereas their violet color petals are mostly ignored and disposed. Saffron petal is one of the most economical sources of anthocyanin pigments. Attractive colour, functional properties and antioxidant properties of anthocyanins can make them a good substitute for synthetic pigments in the food industry. But, due to high moisture content of petals, 96.36% db, they must be dehydrated immediately to prevent the decay. In the meanwhile, the drying conditions are also too critical to petal sensitive compounds while the method of drying along with drying period and the amount of energy consumed, obviously play a significant role on price and quality of the final product.

Materials and methods: In this study, the optimization of the thin layer drying conditions of saffron petal was investigated using response surface methodology (RSM) and Face Centered Experimental Design (FCED) in order to designate the empirical expriments. Saffron petals were dried at different temperatures (40, 50 and 60◦C) and air velocities (0.7, 1.4 and 2.1 m.s-1) in a thin layer dryer and quantitative and qualitative characteristics of saffron petals (color )L: brightness; a: red – green; and b: blue-yellow, total phenolic compounds (TPC), total anthocyanin components (TAC), scavenging activity of DPPH (RSA), ferric reducing-antioxidant power (FRAP) and minimized 50% of radical-scavenging activity (IC50) contents) were invetigated.

Results & discussions: Maintaining the quality of final dried product as high as possible is a major concern while it is an important aspect to consider for use of phenolic compounds and anthocyanins as antioxidants and colorants in food industry. The results showed that the total phenolic compounds (TPC) and total anthocyanin content (TAC) had a remarkable increase with temperature rise from 40 to 50◦C while more temperature increase brought about sharp drops. But, an increasing trend of variations is observed in parallel with increases in velocity of drying air for each temperature. The rise in anthocyanin and phenolic content is more attributed to much significant reduction in drying duration from 40 to 50◦C in comparison with 50 to 60◦C. It was also observed that total antioxidant activity of dried saffron petals showed the same response as TPC and TAC to temperature rise from 40 to 50◦C. Such behaviour could be explained by the findings of other researchers in which the antioxidant activity has high correlation with anthocyanin content and total phenolic composition of food materials. As a complementary, it can be mentioned that polyphenols in an intermediate stage of oxidation have greater antioxidant power than initially even though this is temporary; furthermore high temperature stabilization procedures may lead to the formation of new compounds with higher antioxidant activity. This is essentially the case of the Maillard reaction, which creates various Maillard reaction products, with markedly higher antioxidant power.

Conclusion: Generally, according to Derringer’s desired function approach, the optimal conditions were 50◦C and 1.4 m.s-1.The experimental values agreed with those predicted values. At this optimum condition, the TPC, TAC, DPPH, FRAP, and a value of the dried saffron petal were found to be 46.39 mg/ g ,1205.58 mg/l, 52.97%, 1276.52 µmol Fe2+/l, and 11.13, respectively. The experimental values were in a good agreement with the predicted values.


بی‌نام. 1393. آمارنامه کشاورزی، سال زراعی1394-1393، انتشارات وزارت کشاورزی، معاونت برنامه‌ریزی و پشتیبانی، اداره کل آمار و اطلاعات.
شریفی، م.، رفیعی، ش.، کیهانی، ع.، امید، م. 1389. خشک‌کردن ورقه های نازک پرتقال در خشک‌کن لایه نازک و انتخاب یک مدل ریاضی مناسب. مجله مهندسی بیوسیستم، جلد 41، شماره 1، 67-61.
همتی کاخکی، ع. 1389. بهینه‌سازی عوامل موثر بر تولید رنگ خوراکی از گلبرگ زعفران، مجله علوم و صنایع کشاورزی، جلد 15، شماره 2، 11-19.
Acevedo, N., Schebor, C., & Buera, P. 2008. Non-enzymatic browning kinetics analyzed through water–solids interactions and water mobility in dehydrated potato. Food Chemistry, 108: 900–906.
Azarpazhooh, E., & Ramaswamy, H. S. 2012. Modeling and optimization of microwave osmotic dehydration of apple cylinders under continuous-flow spray mode processing conditions. Food and Bioprocess Technology, 5(5):1486-1501.
Bas, D., & Boyac, I. 2007. Modeling and optimization II: Comparison of estimation capabilities of response surface methodology with artificial neural networks in a biochemical reaction. Journal of Food Engineering, 78: 846-854.
Basti, A.A., Moshiri, E., Noorbala, A.A., Jamshidi, A.H., Abbasi, S.H., & Akhondzadeh, S. 2007. Comparison of petal of Crocus sativus L. and fluoxetine in the treatment of depressed outpatients: a pilot double-blind randomized trial. Prog. Neuro-Psychopharmacol. Biol. Psychiatry, 31(2): 439-442.
Benzie, I.F.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.
Carmona, M., Sanchez, A.M., Ferreres, F., Zalacain, A., Tomas-Barberan, F., & Alonso, G.L. 2006. Identification of the flavonoid fraction in saffron spice by LC/DAD/MS/MS: comparative study of samples from different geographical origins. Food Chem 100(2):445–50.
Catoni, C., Schaefer, H.M., & Peters, A. 2008. Fruit for health: the effect of flavonoids on humoral immune response & food selection in a frugivorous bird. Funct. Ecol., 22(4): 649-654.
Corzo, O., Bracho, N., Vasquez, A .,& Pereira, A. 2008. Optimization of a thin layer drying process for coroba slices. Journal of Food Engineering, 85: 372–380.
Elizalde, B. E., Bressa, F., & Dalla Rosa, M .1992. Antioxidative action of Maillard reaction volatiles: influence of Maillard solution browning level. J. Am. Oil Chem. Soc, 69: 331-334.
Erbay, Z., & Icier, F. 2009. Optimization of hot air drying of olive leaves using response surface methodology. Journal of Food Engineering, 91: 533-541.
Farhoosh, R., & Moosavi, S.M.R. 2006. Determination of carbonylvalue in rancid oils: a critical reconsideration. Journal of Food Lipids., 13: 298–305.
Fatehi, M., Rashidabady, T., & Fatehi-Hassanabad, Z. 2003. Effects of Crocus sativus petals’ extract on rat blood pressure & on responses induced by electrical field stimulation in the rat isolated vas deferens and guinea-pig ileum. J. Ethnopharmacol., 84(2):199- 203.
Francis, F. J. 1989. Food colorants: anthocyanins. Critical Reviews in Food Science & Nutrition. 28: 273-314.
Garau, M.C., Simal, S., Rosello, C., & Femenia, A. 2007. Effect of air drying temperature on physico-chemical properties of dietary fibre and antioxidant capacity of orange (Citrus aurantium v. Canoneta) by-products. Food Chem, 104: 1014–1024.
Giri, S.K., & Prasad, S. 2007. Drying kinetics and rehydration characteristics of microwave-vacuum and convective hot-air dried mushrooms. Journal of Food Engineering, 78(2): 512-521.
Giusti, M.M., & Wrolstad, R.E. 2003. Acylated anthocyanins from edible sources and their applications in food systems. Biochem. Eng. J., 14(3): 217-225.
Gowen, A., Abu-Ghannam, N., Frias, J. & Oliveira, J. 2006. Optimisation of dehydration and rehydration properties of cooked chickpeas (Cicer arietinum L.) undergoing microwave–hot air combination drying. Food Science and Technology, 17: 177-183.
Hammami, C., Rene, F., & Marin, M.1999. Process–quality optimization of the vacuum freeze-drying of apple slices by the response surface method. International Journal of Food Science & Technology, 34(2): 145-160.
Hosseinzadeh, H., & Younesi, H.M. 2002. Antinociceptive and anti-inflammatory effects of Crocus sativus L. stigma and petal extracts in mice. BMC Pharmacol., 2(1): 1-8.
Huang, J., & Ling, Y. 2011. Microencapsulation of anthocyanins from Fruits of berberis kaschgarica Rupr. Food Science, 32(16): 16-21.
Katsube, t., Tsurunaga, Y., Sugiyama, M., Furuno, T., & Yamasaki, Y. 2009. Effect of air-drying temperature on antioxidant capacity and stability of polyphenolic compounds in mulberry (Morus alba L.) leaves. Food Chemistry, 113: 964–969.
Kazuma, K., Noda, N. &, Suzuki, M. 2003. Flavonoid composition related to petal color in different lines of Clitoria ternatea. Phytochemistry, 64(6): 1133-1139.
Koc, B., Yilmazer, M.S., Balk ,R. P.N. & Ertekin, F.K. 2010. Spray drying of yogurt:Optimization of process conditions for improving viability and other quality attributes.Drying Technology, 28 (4): 495-507.
Koocheki, A., & Azarpazhooh, E. 2009. Evaluation of mass exchange during osmotic dehydration of plum using response surface methodology. International Journal of Food Properties, 13: 155-166.
Larrauri, J. A., Ruperez, P., & Saura-Calixto, F. 1997. Effect of drying temperature on the stability of polyphenols and antioxidant activity of red grape pomace peels. Journal of Agricultural & Food Chemistry, 45: 1390–1393.
Madamba, P.S. 2002. The Response Surface Methodology: An Application to Optimize Dehydration Operations of Selected Agricultural Crops. Lebensmittel-Wissenschaft und-Technologie, 35: 584-592.
Mahdavee Khazaeia, S.M., Jafaria, M., Ghorbania, A., & Hemmati Kakhk, A. 2014. Application of maltodextrin and gum Arabic in microencapsulation ofsaffron petal’s anthocyanins and evaluating their storage stability andcolorK. Carbohydrate Polymers, 105: 57–62.
Manzocco, L., Calligaris, S., Mastrocola, D., Nicoli, M., & Lerici, C. 2001. Review of non-enzymatic browning and antioxidant capacity in processed foods. Trends in Food Science and Technology, 11: 340–346.
Maskan, M., & Gogus, F. 1998. Sorption isotherms and drying characteristics of mulberry (Morus Alba). Journal of Food Engineering, 37: 437–449.
Miranda, M., Maureira, H., Rodriguez, K., & Vega-Galvez, A. 2009. Influence of temperature on the drying kinetics, physicochemical properties, and antioxidant capacity of Aloe Vera (Aloe Barbadensis Miller) gel. Journal of Food Engineering, 91(2): 297–304
Montoro, P., Tuberoso, C.I.G., Maldini, M., Cabras, P., & Pizza, C. 2008. Qualitative profile and quantitative determination of flavonoids from Crocus sativus L. petals by LC-MS/MS. Nat Prod Comm, 3(12):2013–6.
Nijveldt, R.J., Van Nood, E., Van Hoorn, D.E., Boelens, P.G., Van Norren, K., & Van Leeuwen, P.A. 2001 .Flavonoids: a review of probable mechanisms of action and potential applications. Am. J. Clin. Nutr., 74(4):418-425.
Nogala-Kalucka, M., Korczak, J., Dratwia, M., Lampart-Szczapa, E., Siger, A., & Buchowski, M. 2005. Changes in antioxidant activity and free radical scavenging potential of rosemary extract and tocopherols in isolated rapeseed oil triacylglycerols during accelerated tests. Food Chemistry, 93: 227–235.
Pabis, S., Jayas, D., & Cenkowski, S. 1998. Grain drying, theory and practice, John Wiely & Sons.
Piga, A., Del Caro, A., & Corda, G. 2003. From plums to prunes: influence of drying parameters on polyphenols and antioxidant activity. Journal of Agricultural and Food Chemistry, 51: 3675– 3681.
Que, F., Mao, L., Fang, X., & Wu, T. 2008. Comparison of hot air-drying and freezedrying on the physicochemical properties and antioxidant activities of pumpkin (Cucurbita moschata Duch.) flours. International Journal of Food Science and Technology, 43(7): 1195–1201.
Rouissi, T., Mahmoudi, A., Tyagi, R.D., Brar, S.K., PrVost, D., & Surampalli, R.Y. 2007.Optimisation of spray drying by response surface methodology for the production of Sinorhizobium meliloti powder formulation by using starch industry wastewater. Biosystems Engineering, 114 (3): 334-343.
Sanchez, F.D., Santos lopez, E.M., kerstupp, S.F., Ibarra, R.V., & Scheinvar, l. 2006. Colorant extraction from red prickly pear (opuntia Lasiacantha) for food application. Electronic Journal of Environment .Agriculture and Food Chemistry, 5:1330-1337.
Severini, C., & Lerici, C. R. 1995. Interaction between the Maillard reaction and lipid oxidation in model sytems during high temperature treatment. Ital. J. Food Sci., 2: 189-196.
Singer, A., Nogala-kalucka, M., & Lampart-Szczapa, E. 2007. The content and antioxidant activity of phenolic compounds in cold-pressed plant oils. Journal of Food Lipids, 15: 137-149.
Sun, D. 2008. Computer vision technology for food quality evaluation.Academic Press, New York.
Tarantilis, P.A., Tsoupras, G., & Polissiou, M. 1995. Determination of saffron (Crocus sativus L.) components in crude plant extract using high-performance liquid chromatography-UV-visiblephotodiode-array detection-mass spectrometry. J Chromatogr A, 699:107–18.
Termentzi, A., & Kokkalou, E. 2008. LC-DAD-MS (ESI+) analysis and antioxidant capacity of crocus sativuspetal extracts. Planta Med., 74(5: 573-581.
Uddin, M.B., Ainsworth, P., & Ibanoglu, S. 2004. Evaluation of mass exchange during osmotic dehydration of carrots using response surface methodology. Journal of Food Engineering, 65:473-477.
Vega-Galvez, A., Lemus-Mondaca, R., Bilbao-Sainz, C., Fito, P., & Andres, A. 2008. Effect of air drying temperature on the quality of rehydrated dried red bell pepper (var. Lamuyo). Journal of Food Engineering, 85(1): 42-5.
Wojdyło, A., Figie, A., & Lech, K. 2014. Effect of Convective and Vacuum–Microwave Drying on the Bioactive Compounds, Color, and Antioxidant Capacity of Sour
Yen, G. C.; & Hsieh, P. 1995. Antioxidative activity and scavenging effects on active oxygen of xylose-lysine Maillard reaction products. J. Sci. Food Agric, 67: 415-420.
Zaiton, H., I. Suzila, M.M.B. Ahmed-Mahir, Y. Salmah & H. Chkzaini. 2009. Quality of roselle tea as affected by drying temperature and storage time. Prosiding Seminar Kimia Bersama.