Measuring Large Granular Food Using the D25LT
The color of large, granular food pieces, such as snack food, beans, pasta, cereal, and dried fruit, must be assessed both to ensure lot-to-lot consistency and, in some cases, as an indicator of completeness of baking or frying. These types of samples are typically non-uniform in size and shape. Therefore, special accessories and presentation techniques are required to provide repeatable results. Generally, a sampling of a number of chips or cereal pieces should be measured together in order to obtain an overall average of the color of the batch. Several readings of the group of pieces should be averaged for the final result, preferably with replacement of the sample between measurements.
A HunterLab D25LT 45/0 colorimeter can be used to measure the reflectance of batches of samples with the instrument in the port-up orientation and the samples in a glass or plastic sample cup or dish. This is the most common method advocated by HunterLab for the measurement of chips and cereal. This method also applies to other large, granular pieces, such as pet food, nuts, beans, dried fruit, pasta, gumballs, and candy.
The D25LT Port Up
The Application
Chips and cereal have several non-uniform characteristics that require compensating preparation and presentation techniques in order to ensure a repeatable sample measurement.
The available measurement area of individual pieces may be very small and/or curved. A group of samples must be measured through the clear window of a glass or plastic cup or dish in order to be effectively made into a solid.
These pieces are irregular in size and shape, requiring the averaging of several readings with replacement.
| Recommended Color Scale | CIE L*a*b* or Hunter L, a, b as a full color descriptor |
| Recommended Illuminant/Observer | C/2° |
Measurement Method
| 1. Configure the touch screen software to read using the desired color scale, illuminant, and observer. | |
| 2. Standardize the instrument using the black and calibrated white standards that come with the instrument. |  |
| 3. Scoop up or pour pieces from the sample batch to fill the 5-inch glass sample cup (HunterLab Part Number 04-7767-00) or a large Petri dish. |  |
| 4. Place the sample cup in the sample presenter guide so that the sample pieces will be read through the glass bottom of the cup. |  |
| 5. Take a single color reading of the pieces through the bottom of the sample cup. Dump, refill, and read the pieces at least three times from the same batch or rotate the dish so that the sample is viewed from a different angle. Average the three color readings for a single color measurement representing the color of the batch. Averaging multiple readings minimizes measurement variation associated with non-uniform samples. | |
| 6. Record the average color values for the sample batch. |