Dried chilli quality
Factors that affect the colour and quality:
Factors that affect the colour of dried chillies include the cultivar, the stage of maturity at harvest and subsequent curing, fruit drying conditions, and the final moisture content. At less than 10% moisture, the colour appears bleached, while at levels greater than 10% there is darkening, possibly caused by non-enzymatic browning. The colour of crushed or ground chilli powder deteriorates faster than whole chillies, due to the auto-catalyzed degradation of carotenoids.
The major factor influencing colour retention during storage is the temperature, followed by the moisture content. The effect of air, light, and type of container is minimal. The optimum storage conditions for chilli powder colour retention are 16ºC and 10–11% moisture.
The American Spice Trade Association (ASTA) has set standards for measuring colour in pepper products that are widely followed. Samples are extracted by acetone and the absorbance is read by a spectrophotometer at 460 nm. Values are expressed as ASTA units; a value greater than 200 is considered a very deep red colour. Commercial samples of chilli powder normally range from 100–200 ASTA units, and a premium may be paid by processors for lots with extractable colour greater than 140 units.
Similarly the standard for measuring pungency in all forms of peppers is Scoville Heat Units (SHU).The Scoville scale is a measurement of the spicy heat of a chili pepper. The number of Scoville heat units (SHU) indicates the amount of capsaicin present. Basically the pungency of the chilli depends on the location in which chilli is grown and the genetic structure of the chilli. The pungency of the chilli is due to the capsaicin. The scale is named after its creator, American pharmacist Wilbur Scoville. His method, devised in 1912, is known as the Scoville Organoleptic Test. In Scoville’s method, an alcohol extract of the capsaicin oil from a measured amount of dried pepper is added incrementally to a solution of sugar in water until the “heat” is just detectable by a panel of (usually five) tasters; the degree of dilution gives its measure on the Scoville scale. Thus a sweet pepper or a bell pepper, containing no capsaicin at all, has a Scoville rating of zero, meaning no heat detectable. The pungency of the peppers is rated in multiples of one hundred SHU. It has largely been replaced by high-pressure liquid chromatography (HPLC), which is relatively rapid and reliable compared to the Scoville Organoleptic test.