Influence of soil composition and drying methods on chemical and physical quality evaluation of saffron

摘要

The quality of saffron is generally evaluated according to the specifications in ISO 3632-1 where the moisture and volatile matter content and the spectrometric analysis of flavour strength (expressed as picrocrocin), aroma strength (expressed as safranal) and colouring strength (expressed as crocin) are considered to be the most important characteristics. Buyers however are often interested in physical characteristics such as olfactory, palpable and visual aspects. In this research, the influence ofsoil composition and postharvest drying practices on chemical and physical characteristics of saffron is discussed. In case influencing factors are identified, producers can use these in their choice of fields, potential correction of soil nutrient composition and choice of drying method. Secondly, we want to determine whether there is a correlation between the chemical analysis and physical evaluation of saffron, to see if physical characteristics can be used as a first indication of chemical composition in cases where it is impossible to analyse according to ISO 3632-2. Forty-five saffron samples from the 2015 harvest in the region of Taliouine, Morocco are analysed. The chemical analysis of water and volatile matter content, picrocrocin, safranal and crocin aborbance is performed according to ISO 3632-2 (2010). The physical evaluation is based on the methodology applied by saffron merchants in the region of Taliouine. Saffron from altitudes above 1800 m seems to exhibit a less intense aroma than saffron from lower altitudes, but the difference is not statistically significant (p>0.05). The drying method (shadow, sun or electrical food dryer) influences the colour of the yellow part of the style (p<0.05). Further research on the effect of the recent introduction of food dryers in Taliouine on saffron quality is required. A weak correlation is found for the combination of colour and aroma intensity as a predictor for safranal and crocin absorbance.