How to Measure the Color of High-Fiber Drinks Such as Carrot Juice and Tomato Juice?

Orange juice (unfiltered), carrot juice, tomato juice , mango juice, peach juice and other high-fiber drinks are rich in dietary fiber, which makes their color not as transparent and clear as clear juice . It is not recommended to use transmission measurement to measure color. Reflection measurement is recommended to measure juice color. This article introduces how to use appropriate methods and equipment to accurately measure the color of high-fiber drinks, ensure product color stability, and improve market competitiveness.

Steps for Measuring the Color of High-Fiber Drinks Such as Carrot Juice and Tomato Juice

1. Sample Preparation: Ensuring Consistency and Homogeneity

High-fiber drinks such as carrot juice and tomato juice often contain suspended particles and fiber, which can lead to uneven color distribution, and direct measurement may affect the accuracy of the results. Therefore, sample preparation is a critical first step:

• Filtration or homogenization: If there are many suspended particles in the beverage, you can filter it first or use a homogenizer to mix the sample to reduce the effect of particles on light scattering and ensure the consistency of color measurement. For example, pulp particles in tomato juice may interfere with the light path, and homogenization can make the sample more uniform.
• Dilution (optional): For darker colored samples (such as concentrated tomato juice), appropriate dilution can be performed to avoid saturation of the instrument's detection range, but the dilution ratio needs to be recorded and kept consistent for subsequent calculations.
• Stirring: Stir the sample thoroughly before measurement to ensure homogeneity.
• Temperature control: Keep the sample at a constant temperature (usually room temperature, about 25°C) because temperature changes may affect the stability of pigments, such as beta-carotene in carrot juice, which may degrade at high temperatures.
• Avoid oxidation: High-fiber drinks are susceptible to oxidation due to exposure to air (e.g., the orange color in carrot juice may darken due to oxidation). It is recommended to minimize the sample exposure time before measurement, or add a small amount of antioxidants (e.g., vitamin C) to the sample to slow down oxidation.

2. Choose the Right Instrument: 3nh YS3X Series Spectrophotometer

It is recommended to use 3nh YS3X series spectrophotometers (such as YS3010, YS3020, YS3060). These instruments have the following advantages in the color measurement of high-fiber beverages:

• High-precision measurement: 3nh YS3X series instruments use spectrophotometric technology, which can measure the reflectance spectrum of samples at different wavelengths, providing detailed color data (such as CIELAB, Hunter Lab parameters), suitable for pigment analysis of carrot juice orange-yellow (dominated by β-carotene) and tomato juice red (dominated by lycopene).
• SCI/SCE mode: High-fiber drinks may produce surface scattering due to particles. The 3nh YS3X series supports SCI (specular reflection included) and SCE (specular reflection excluded) modes, which can measure the true color and surface gloss of the sample respectively, helping to eliminate the interference of fiber particles on the measurement.
• Color Difference Analysis: By measuring the color difference ΔE, the 3nh YS3X series can quantify the difference between the sample and the standard color, suitable for batch-to-batch quality control.
• Geometric conditions: 3nh YS3X series instruments have a D/8 (diffuse illumination/8° observation angle) geometric condition, which complies with the food color measurement standard recommended by CIE and can reduce light scattering interference caused by uneven sample surfaces (such as fiber particles).

3nh YS3060

3. Instrument Calibration and Measurement Condition Setting

When measuring the color of high-fiber beverages, instrument calibration and standardization of measurement conditions are very important:

• Calibrate the instrument: Use the standard white and black boards that come with the 3nh YS3X series instrument to calibrate to ensure the accuracy of the measurement results.
• Select light source: D65 light source (simulated daylight) is usually used because it is the standard light source for color measurement in the food industry and can truly reflect the color of carrot juice and tomato juice under natural light.
• Sample container: Place the sample in a clear, colorless optical glass or plastic cuvette, making sure the container does not interfere with the light path. The thickness of the cuvette should be consistent (e.g. 2mm or 10mm) to ensure the stability of the light path.

4. Measurement Process

a. Multi-point measurement: Since high-fiber drinks may have local color unevenness, it is recommended to perform multiple measurements (at least 3 times) at different locations of the sample and take the average value to improve the reliability of the data.

b. Observation data: 3nh instruments can automatically store the measured CIELAB parameters (L represents brightness, a represents red-green axis, b* represents yellow-blue axis) and color difference ΔE . For example:

• Typical color data for carrot juice might be high L* (bright), positive a* (redder), and high positive b* (yellower).
• Tomato juice generally exhibits a higher L*, a higher positive a* (red), and a lower b* (little yellow).
• Color difference ΔE, to ensure color consistency meets quality standards (usually ΔE < 1.5 is considered acceptable).

5. Data Analysis and Application

Color stability monitoring: By regularly measuring the color data of carrot juice and tomato juice, color changes during production can be monitored. For example, oxidation or high temperature sterilization may cause the b value of carrot juice to decrease (yellowness decreases), while the a value of tomato juice may decrease (redness decreases) due to lycopene degradation.

Color adjustment: If the color deviation is large, you can combine 3nh color management software to adjust the production process by analyzing spectral data (such as adding antioxidants and optimizing sterilization time).

Quality Control: Compare measurement data to industry standards, such as food color specifications, to ensure product color meets consumer expectations.