Measuring Baked Goods Using the ColorTrend HT
The color of baked goods, such as rolls, cookies, and crackers, can be assessed immediately after baking, while still on the line, using the ColorTrend HT. Such measurements provide information about product quality and sufficiency of baking. Color measurements can help reduce costs associated with color complaints and can indicate where there is a process upset, such as a temperature set too high or too low. On-line measurements allow you to react quickly to such upsets and to measure product constantly, rather than just intermittently in the laboratory.
There are a number of process variables that can impact the color of baked goods. Typically, control parameters such as operating temperature, line speed, and dwell (or resident) time all have an effect on color. In order to determine how these variables affect color, it is important to first get real-time measurements of color that can be tracked accurately and consistently from the beginning stages of a run through to the finished product. This information helps determine the causes and effects of process variation, allowing prompt corrective action to minimize off-quality product, increase production throughput, and maximize equipment usage. As a result, plant operating costs are ultimately reduced and overall product quality is improved. On-line measurements also result in reduced laboratory labor and material sampling costs, as the laboratory quality control function is reduced to infrequent auditing.
The ColorTrend HT
The Application
Typically, the ColorTrend HT sensor is mounted above the conveyor belt just after the oven. (Mounting over the oven band is not recommended.) The baked goods pass under the sensor in lines and the instrument measures the goods that it "sees" and provides colorimetric data that is updated frequently.
| 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. Position the ColorTrend HT over the product on the line. The ColorTrend HT viewing window should be 3-4 inches from the product surface. The instrument can compensate for height, so small differences in the height of the product is not of concern.
2. Configure a product setup for each type of baked product with the following parameters:
...*Parenthetical entries refer to terminal wording where it differs from that of the Utility Software.
| ... | Set-up Number | Your choice |
| Set-up Name (Product Name) | Your choice | |
| Color Scale | L*a*b* (CLab) | |
| Product Target Values (Target Values) | Establish using the read button with an ideal product standard, if desired (Enter values for ideal product standard, if desired) | |
| Chart Color Index (Display Height) | No (Yes) | |
| Hitch (Enable Hitch) | Off (No) | |
| Average | 1 | |
| Read Mode | Piecewise (Piece) | |
| Hold Time | 5 seconds | |
| Data Mode | Absolute | |
| Datalogging Interval | 1 second or more | |
| Background Distance | Recalculate for this product | |
| Cut-off Distance | Recalculate for this product | |
| Units (Height Units) | Your choice | |
| Alert Limit | Enter color values beyond which alert should be given | |
| Alarm Limit | Enter color values beyond which alarm state should be activated | |
| Analog Outputs (Channel Centers/Channel Spans) | If analog outputs available, enter appropriate values | |
| Filter | Disabled (0.0) | |
| Color Tracking (Track Color) | On and enter limits (thresholds) | |
| Tilt Angle | 0° | |
| Standardization Interval | If autocalibrator, available, enter appropriate choice | |
| AC Frequency | Enter appropriate value | |
| White Tile Values | Do not change values shown |
3. Begin the run.
4. Modify the target values and limits as necessary to optimize the process. The ideal situation is one where the reading of defective product immediately causes the alarm state to be activated, but acceptable products continue to be read as usual.