Method 21.0 Scoville Heat Test (SHU)
Method 21.0 Scoville Heat Test (SHU)
Purpose: To determine pungency in Capsicum spices and oleoresins, via SHU "taste" analysis.
Erlenmeyer flask, narrow neck, 125 ml. with ground glass stopper.
Pipette, serological, 1 ml. capacity, 0.01 ml. graduations.
Pipettes, volumetric transfer 2 ml. and 5 ml. capacity.
Volumetric flasks, stoppered, 50 ml. capacity, 100 ml. capacity.
Funnel, analytical 58°, short stem.
Filter paper, Whatman No. 1, 12.5 cm.
Ethyl alcohol, 95%
Sucrose solution, 5% sucrose in tap water (w/v) i.e. 50 g. made up to a liter.
C. Preparation of Samples:
Ground capsicums and oleoresins should be used as is. Prepare unground capsicums as directed in Method 1.0. Oleoresins should be mixed thoroughly before taking sample.
Make an alcoholic extract of the sample based on anticipated pungency. Ground Capsicum should be extracted for a minimum of 16 hours. Shake occasionally. An Oleoresin sample can be dissolved and used immediately.
Decant or filter to get a clear extract.
For the material to be tasted, dilute the quantity to 50 ml. with 5% sucrose solution using pipettes and volumetric flask. In any given test start with an amount of alcoholic extract considered to be too small so that negative response will be obtained and increase the amount three out of five tasters report positive results. Record individual response to each dilution. For selection of panelists see Note 1.
Before the first tasting and between each tasting have the individuals sip or rinse their mouth with water at 90°-100°F.
For tasting, 510.1 ml. aliquots of the solutions prepared as indicated in step 3 are to be swallowed one at a time from small cups. The judgment as to whether or not heat is present is to be made between 20 and 30 seconds after swallowing. The minimum interval between tasting the solutions should be 5 minutes. (See Note 2).
Tasters are to continue through the sequences of solutions until each reports a definite burn sensation. (See Note 3). Report the heat units for the first solution for which three out of the five panelists report positive.
A panel of five reliable tasters is required.
Potential panelists should be given several trials at tasting a series of solutions which is known to contain the threshold heat response. A Capsicum sample analyzed previously is suitable. The panelists' results for several days can be compared for agreement and with results of experienced individuals. It is important for potential panelists to learn their own threshold sensation to Capsicum heat. For example, where the sensation occurs in their mouth. This experience may build sufficient confidence in individuals for them to judge their own performance. Some individuals may not qualify because of extremely poor repeatability. Others may not be capable of utilizing their taste sensation. Finally the threshold level of Capsicum is not necessarily the same for each person. Results of this procedure can be biased if panelists are chosen for high or low sensitivity. A panel of five is not expected to indicate a threshold reaction on the same dilution. In fact, the pattern of positive response may include a range of dilutions.
Experienced panelists who have respiratory infections, a recent exposure to highly seasoned foods or medications may be incapable of a reliable response. For this reason it is helpful to maintain experienced alternates.
An experienced panel may be capable of good performance without waiting 5 minutes between solutions. But allow 1.5 hours between panel sessions.
A great deal of time will be wasted if the panel is given solutions which are far too dilute. Therefore, knowledge of approximate Scoville value is a great aid in presenting the least number of solutions. In addition, the individual preparing the extract and solutions can perform preliminary tasting. Although, this will eliminate them from immediate participation as one of the five member panel.