Abstract
The dehydration process is the basis to obtain high quality saffron and to preserve it for a long time. This process modifies saffron’s main metabolites that define its quality, and are responsible for the characteristic color, taste, and aroma of the spice. In this work, the effect of microwave dehydration on saffron main metabolites (picrocrocin, safranal and crocetin esters) from Crocus sativus L. stigmas at three determinate powers and different time lapses was evaluated. The results showed that this dehydration process obtained similar or lower crocetin esters content, and after three months of storage, higher concentration was shown in treatments at 440 W for 36 s, 55 s, and 73 s; at 616 W for 90 s; and at 800 W for 20 s. Picrocrocin content was lower and safranal content was higher in all treatments compared to the control both before and after storage. Regarding to commercial quality, microwave dehydration obtained Category I of saffron according to International Standard Organization (ISO) 3632. After three months of storage, treatments at 616 W for 83 s and 800 W for 60 s obtained lower categories. The results obtained suggest that microwave dehydration is a suitable process for obtaining high quality saffron, 800 W with 6 lapses of 20 s being the best conditions studied.
Highlights
Saffron is the dried stigmas of Crocus sativus L. and its high value is due to its colour, flavour, and aroma [1]
Saffron in Spain is obtained by C. sativus L. stigmas dried by a process called “toasting”, in which stigmas are put on a sieve with a silk bottom placed over a heating source, whereas in other countries, in terms of temperature, stigmas are dehydrated at room temperature under sunlight or in the shade
The control sample consists of a part of fresh stigmas that were dehydrated according to the own company’s internal procedures, considering that this saffron belongs to Protected Designation of Origin (PDO) “Azafrán de La Mancha” [4,31]
Summary
Saffron is the dried stigmas of Crocus sativus L. and its high value is due to its colour, flavour, and aroma [1]. Stigmas’ dehydration is the key process to obtaining the spice and is responsible for saffron composition [4,5,6] During this process, stigmas lose around 80% of their weight and, according to the International Standard ISO 3632 (2011) [7], moisture must be lower than 12% in order to preserve the spice for a long time [8]. Depending on the physical and chemical characteristics of saffron, it is classified into one of the three categories established by the ISO 3632 (2011) standard This international standard is principally used to determine the saffron quality in international commercial agreements, colouring strength being the main parameter from which its price is set. The quality of this spice is measured via Ultraviolet-visible (UV-vis) spectrometry, according to ISO 3632 (2011), this method does not provide a precise determination of picrocrocin and safranal concentration [15]
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