The method of drying saffron has a great effect on the quality and value of the final product. In different countries and regions, saffron is dried in different ways. The special and extraordinary aroma of saffron is produced during drying due to the hydrolysis of picrocrocin compounds and the release of safranal.
Drying and packaging of saffron are the most important stages of saffron production. During the drying or marketing period, the moisture content of saffron is reduced to 15%. To keep saffron longer, the moisture content should be reduced to 12%, which is called drying saffron. It is related to 3632/ ISO / TS.
According to experts, the difference in the quality of saffron from different regions is determined only by the drying condition of saffron And not based on genetics or climatic differences and the like. In general, the lower the drying time with the right amount of temperature, the less quality saffron changes.
1- Drying saffron in the traditional way (the traditional Iranian method)
In this method, after separating the stigma and cream from the flowers and classifying the saffron, they are placed in a row at room temperature, in the sun or in the shade of the sun, inside lattice drains or in a special basket or spread on cloth and paper. Drying time in this method is 15-10 days.
Another way, Saffron is placed inside thin cloths on a wire mesh and a thin cloth is pulled on it to prevent direct sunlight on it. Due to the hot air and high air pressure outside, the drying time in this method is reduced to 2-3 days.
This method of drying saffron has disadvantages, the main of which is the prolongation of drying time. Increasing the time allows the growth and multiplication of microorganisms, increases the amount of pollution and also reduces the quality of saffron. In recent years, this method has gradually become obsolete and has been replaced by other suitable methods.
2- Testing method (sieve and heater)
This method is also known as the Spanish method. It should Use a sieve or silk cloth. In this method, sieves with a diameter of 30 cm and with a silk net were used. Fresh saffron stigmas are placed in a layer 2 to 3 cm thick on the grid and then the sieve is placed at a suitable distance from the heat source.
After setting the temperature, put the net containing the saffron (150- 200gr) on the machine for 15 to 20 minutes, and in this case, the saffron will not be touched in any way. After 20 minutes, place another empty net on the net containing the saffron and take each round of the net together so that the saffron is completely emptied in the second net. The net is placed on the device again and the same operation is repeated after 15 minutes. This is done 3 to 4 times.
Weaknesses and strengths of Spanish sieve and heater method:
- Due to the inaccuracy of the amount of heat produced by the heaters, sometimes due to the carelessness of consumers, saffron suffers from burns and bag drops.
- It is not possible to control the humidity.
- The quality of the final product is relatively good.
- Its speed of action is considerable.
- The price of the device is low and as a result it is possible for all to use it.
3- Electric oven
The use of electric oven with adjustable temperature of 60-50 degrees Celsius and special trays with silk nets is another way to dry saffron. In this method, saffron is dried in a layer 1-2 cm thick for 40-30 minutes at high temperature. In this method, the color strength and aroma of the resulting saffron is high.
4- Freezer dryer
In this method, first put the product at a temperature of -22 to -18 degrees Celsius for 20 hours and then They are placed at -13 C for 0.15 mmHg for 12 hours. In this method, the amount of crocin pigment in the product is very high. It should also be noted that the color of the resulting saffron will be reddish orange, which is not a desirable color in terms of appearance due to the incorrect mentality of consumers about the redness of saffron.
5- Solar dryer
This device consists of layers on which saffron stigmas are placed and moisture is lost and dried by absorbing the sun’s rays.
6- Air Dryer
Here hot air comes in direct contact with the product. The most important of these are tunnel dryers. In this method, the stigma is separated from the petals by a cutting machine and loses 50% of its moisture by passing through the heat tunnel. Then the product is separated by using wind force and based on the difference in volumetric mass by passing through an electric device.
7- Vacuum dryers
These types of dryers have a complex process for drying materials and are mostly used for drying materials that are sensitive to heat. The reason for this is the mechanism of this device. Initially, the product in the chamber is placed in a vacuum condition and the temperature is heated by low pressure and high pressure hot air. Time and temperature in this device is lower than other methods and the product has a higher quality.
Evaluation of different drying methods in saffron quality
The purpose of saffron drying is to observe three points:
- Saffron should reach the consumer almost in its original form, there should be no differences in color, smell and taste.
- Prevent chemical, physical or biological changes of dried saffron during storage.
- Protect it from bacterial contamination.
Different methods of drying saffron with different degrees of heat have been tested and you can see the results:
Four main different methods of drying saffron, including the traditional Iranian method, the Spanish method (using a sieve or silk cloth), electric oven and vacuum dryer have been studied on the main and important components of saffron (compounds that cause color, taste and aroma). The results showed that the color of saffron in the method of drying with an electric oven at 60 ° C for 5.2 hours was superior to the other three methods, and the Spanish method was next.