When customers choose beverage products on the shelf, they demand not only a first-rate taste but also a consistent appearance. Color and clarity are essential quality criteria: any defects can indicate contamination, raw material mix-ups, or heating and oxidation during production.
However, controlling the production process of fruit and vegetable juices, beer, and flavored liquor is not easy for manufacturers. For one thing, the color of natural ingredients, such as fruit, can vary. Furthermore, the raw materials for mixed drinks can involve a variety of liquids, solids, and powders. Even small color deviations between batches can result in significant color variations in the final mixed drink.
To control the color of liquids and achieve consistent color appearance, you need to have the right tools to collect color data and implement the right processes to identify and adjust for color variations.
Liquid Color Measurement Tools
1-Spectrophotometer
To measure liquids, visual inspection is clearly insufficient. You need a non-contact, ideally precise spectrophotometer to prevent contamination of colored samples or the lens from covering the beverage film, which can cause measurement errors or damage the spectrophotometer. You also need a reflectance or scattering spectrophotometer, depending on the liquid’s opacity or translucency.
1) Measuring opaque liquids
To measure the color of opaque liquids such as cider, stout, and juice, a reflectance spectrophotometer is used. A glass cuvette holder, mounted on the front of the device, holds the opaque liquid in the correct position for color measurement. The measurement device shines light onto the sample and quantifies the color data by capturing the light reflected back to the lens.
If you are only measuring opaque liquids like juice, you can purchase the lower-priced TS8210 for opaque liquids that can be measured in reflection mode.
2) Measuring translucent liquids
For transparent dyes and beverages (such as apple juice, white wine, mineral oil, vinegar, olive oil, and light beer), which are colored but generally translucent, reflectance measurements are not suitable. Some light waves pass directly through the sample rather than being reflected. To measure translucent liquids, a spectrophotometer that supports scattering measurements is required.
Gardner liquid Spectrophotometer TS4020
A scattering spectrophotometer places a liquid sample in a glass cuvette or colorimetric container within the instrument. The device passes the visible spectrum directly through the sample and uses a receiver on the other side to capture the proportion of transmitted light at various wavelengths. The relatively transparent liquid absorbs some of the white light component, allowing others to pass through. This data is used to quantify the sample’s color.
Many benchtop spectrophotometers support both reflectance and scattering measurements. This pink, translucent liquid is being measured.
3) Simultaneous measurement of opaque and translucent liquids
If you want to measure two liquids, you don’t need two instruments. Many benchtop spectrophotometers support both reflectance and scattering measurements.
2-Quality Control Software
Quality control software facilitates quantification of final measurement results, whether measuring the color of transparent liquids using scatterometry or opaque liquids using reflectometry. Thus, a known standard or CIE colorimetric standard can be entered and compared to the measured sample to check whether it meets the set tolerances. The software will plot the standard and sample in the L*a*b* color space to visualize the results.
The following points can be understood through color measurement data.
1) Is the color accurate?
Color measurement data from the QC phone can show whether the manufactured color is within tolerance. If the liquid is mixed, the type and amount of colorant can be adjusted accordingly to change the color, and the software can help you quantify which color to add to meet the tolerance requirements.
2) Is the liquid too opaque or translucent?
Color measurement data can indicate that the pulp or impurities need to be filtered, rather than that there is not enough light. On the other hand, if the liquid is too clear, it can help determine the amount of dye to increase.
3) Does it meet a specific color index or have a specific quality level?
For liquids like natural beverages or gasoline, you can’t add additional dyes to change their color. In this case, color measurement data can determine whether a product meets the international standards and color scales defined by ASTM. For example, there’s a color calculation method called the OJ Index. A light orange batch number still allows for a delicious blended juice, but the light color might jeopardize USDA approval and raise consumer concerns about quality. Proving that a single parameter in a mobile phone meets ASTM requirements can be used to sell juice at a higher price.
The interface shows that the ColoriQC measurement results of the sample and the CIE standard color index of the green sample are within the tolerance range, indicating that the requirements of the specific juice are met.