Production Practices and Quality Assessment of Food Crops. Vol. 1

246 S. A. Ordoudi and M. Z. Tsimidou
Figure 18. Illustration of piled frames for saffron drying.
meters on a piece of paper hanged on the wall is more useful than memorising them.
In this way, each processor creates his/her own archives. The temperature should
be kept within the region of 35–45 °C while the relative humidity should not
overcome the 50%. The total time for the drying depends on the room dimensions,
the conditions of temperature and relative humidity as well as the frame loading.
Sorting. The sorting of stigmas from the stamens and the remaining floral matter
is a crucial stage of the processing. Producers who are also the processors of their
product should always have in mind the necessity of keeping all the surfaces clean.
Except for a flat surface (Figure 19), a pair of forceps could be used to assist sorting.
In order to comply with ISO specifications it is a good idea to repeat sorting 2–3
times per batch.
Indian saffron is not of high quality most possibly due to the lengthy sun drying
processing periods that may cause both biodegradation and oxidative destruction
of the principle components (27–53 h) (Sampathu et al., 1984). Raina et al. (1996)
worked on the processing conditions used in India and also elaborated some drying
schemes at a laboratory scale. The authors collected samples from the two major
saffron producing areas of India (Sringar and Kishtwar) for three successive
years. The drying methods employed were (i) shade drying, 4–18 °C; ii) sun drying,
11 h photoperiod per day, 12–21 °C; iii) solar drying, highest interior temperature
49 °C (29 °C higher than the ambient; iv) dehumidification drying over Si-gel
(blue), 40 °C; v) in a vacuum oven at 40, 50 and 65 °C and at reduced pressure
of 40 mm; vi) in a cross-flow oven at 20, 40 and 50 °C and vii) in an electric
oven at 40, 50, 65 and 80 °C. The optimum tray-load was found to be 1 kg m –2 .
The findings were very close to those found for Greek saffron drying conditions.
The proposed temperature for artificial drying was 40 ± 5 °C. At lower temperatures,
lengthy periods of processing were experienced that resulted in pigment loss
whereas at 50 or 60 °C thermal degradation of pigments was prevailed. Vacuum
and cross-flow drying caused a significant reduction in safranal content but at the
same time increased levels of 4-β-hydroxysafranal were observed that had as a result