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What Is the Best Way to Measure the Color of Citrus Juice?

Posted on Feb 06, 2026 by HunterLab

The best way to measure the color of citrus juice, like orange juice, is by using a spectrophotometer, which will accurately handle the unique composition of the natural ingredients. Elements like common citrus juice color indices and color scales and 45°/0° measurement geometry in your testing system will help you adhere to industry standards.

Use the Right Technique to Measure Citrus Liquids

When measuring a citrus juice like orange juice, you'll be testing an opaque liquid. The opacity or transparency of your beverage will determine which mode you'll use for measuring. Opaque juices should be measured in reflectance spectrophotometric mode, while translucent drinks can be measured in reflectance or transmittance spectrophotometric mode.

Measure Your Liquid Samples With a Contactless Method

What Is the Best Way to Measure the Color of Fruit Juices?

Posted on Feb 06, 2026 by HunterLab

A spectrophotometer is the best way to determine the color of fruit juices, as it measures color similar to how the human eye works. It's best to maximize objectivity by quantifying color through the use of industry standard color scales. When you measure the color of a juice using a spectrophotometer, the result is expressed in percentage or number form, eliminating room for error and eye fatigue from subjective methods.

Measure Fruit Juices Using the Right Equipment

Fruit juices can vary in opacity, meaning light won't travel through various beverages the same way. Use a reflectance spectrophotometer to measure opaque liquids like guava or orange juice accurately and employ a reflectance or transmittance spectrophotometer for translucent beverages like apple juice. Selecting the right tools helps you produce accurate results.

What Standard Do I Use to Verify Yellowness Index Performance?

Posted on Feb 06, 2026 by HunterLab

The Yellowness Index from ASTM International provides a measurable standard for assessing the yellowness in white or light-colored materials, such as plastics. This standard determines the degree of yellowness present, allowing companies to perform quality control processes to maintain product consistency. The test uses a spectrophotometer to quantify the color measurement.

The APHA color system is the most common measurement scale for measuring yellowness in liquids. It serves industries ranging from chemical production to pharmaceutical development.

Materials That Require Yellowness Observations

Various plastics require yellowness observations due to the changes these materials undergo in processing. These plastics include:

Polyvinyl chloride (PVC)
Polycarbonate (PC)
Purified terephthalic acid (PTA)
Polyethylene terephthalate (PET)

Yellowness appears in PET due to oxidation. With the increasing use of recycled PET (rPET), manufacturers must measure color to counter yellowness and determine the correct ratio of optical brighteners required to mitigate it.

What Is the Yellowness Index?

The Yellowness Index (YI) measures yellowness due to product changes. The ASTM E313 Yellowness Index is the most common method for determining yellowness in materials like plastics. The standard gives defined indices for measuring the shift from ideal white. It is calculated according to the following formula:

YI = (100CxX - CzZ)/Y

The X, Y, and Z variables are CIE Tristimulus values, which express color and how it is perceived. Cx and Cz depend on the illuminant and observer. During calculations, users choose the values for these coefficients from a table to correspond with spectrophotometer settings. The ASTM E313 combines the calculations into a single value, defining the yellowness amount in a sample. The lower the number, the less yellow the material is.

The YI value is commonly reported as the difference in yellowness between a product sample and the original or reference, designated as delta YI (∆YI).

When Is Sample Averaging Appropriate in Color Measurement?

Posted on Feb 06, 2026 by HunterLab

Carpet samples can be challenging to measure because the texture may make the product appear lighter or darker than it really is. Averaging your sample measurements can help you overcome this challenge. Image Source: Shutterstock user Alena Ozerova

Some textiles are more difficult to test for color consistency than others. A textile manufacturer can easily test a swatch of solid blue jersey fabric because the material is flat, opaque, and homogenous. For these types of smooth, solid textiles, all the manufacturer has to do is take one reading on a spectrophotometer to determine whether the dyed jersey fabric meets the manufacturer’s color standards. But not all textiles are homogenous in color; fabrics like corduroy, heavy knits, and terry cloth have texture variations that making them much more difficult to measure with a spectrophotometer. If the manufacturer measures the color of such fabrics in just one small area of the sample, there’s no guarantee that this measurement will match other measurements taken of the same fabric—move just one inch to the right of your first measurement and you’ll likely find that the color reading is completely different.

When testing for color consistency, how do manufacturers compensate for textured or non-homogenous products like this? One method is to average the color measurements in order to get an overall sense of the product’s color. By averaging your sample measurements, you’ll ensure that your color readings are as accurate as possible, even when working with materials that vary significantly in texture. However, in order to use this method properly, you’ll need to know when it’s appropriate to average your samples and when you should take only a single reading. After all, taking multiple measurements of the same sample can be a time-consuming process, so it’s important to only average measurements for the products that actually require this added level of attention.

Averaging your measurements can help you get an accurate color reading on products like toothpaste, especially those that contain flecks of colorful suspended particles. Image Source: Shutterstock user kikovic

Perfecting the Appearance of Light and Dark Rums Using Spectrophotometric Technology

Posted on Feb 06, 2026 by HunterLab

Rum ranges dramatically in color, clarity, and flavor, from clear as water and virtually tasteless to deep brown and rich in complex flavors. In fact, you can often tell a great deal about the flavor profile and quality of rum simply by looking at the color and clarity of the liquid inside of the bottle. This is why most rum producers distill, filter, and age their rum carefully in order to achieve the perfect appearance. However, a multitude of factors affects the appearance of rum before it is bottled, potentially compromising both the look and taste of the product. For example, if the rum spends too much time in the barrel or it hasn’t been filtered enough, then it may not be as rich in color or as clear as the producer would like and the taste may not be what customers expect.

In order to achieve correct and consistent appearance of rums, many manufacturers are turning to spectrophotometric technology. Whether you want to create perfect clarity in a bottle of light rum or you need to ensure that your dark spiced rum is the same shade of amber after it’s removed from the barrel, spectrophotometers can help you reach your goals.

6 Common Color Measurement Mistakes

Posted on Feb 06, 2026 by HunterLab

Color measurement is a precise science requiring an objective, practical, and effective approach. Accurate data and consistency improve customer satisfaction and product quality across industries ranging from food to plastics. When you know the most common mistakes made in taking accurate measurements, you can proactively prevent or avoid them and capture data you can have confidence in.

1. Relying on Subjective Descriptions and Visual Assessment

People perceive color differently, so subjective descriptions like “navy blue” can't accurately quantify it. In contrast, measuring according to the CIELAB color scale might give you a value of L*= 15, a*= -6, b*= -25, so you'll have an exact number to compare.

Visual assessment leads to color measurement problems due to a lack of optical memory and physiological dysfunctions that influence perception. Even trained eyes with superior detection ability can become fatigued, compromising accuracy.

2. Not Using a Software Program

A software solution simplifies measurement collection and comparison, making it a powerful tool for enhancing spectral data analysis.

3. Not Considering Environmental Factors

Metamerism describes the phenomenon where two colors match under one light but not another, which creates issues with color consistency. A spectrophotometer, which contains a standard light source, combats this phenomenon. Other environmental factors that can influence color include temperature and humidity, which alter the way a material interacts with the wavelengths. Controlling these within your facility can help promote more accurate measurements.

Best Spectrophotometer for Measuring Transmittance Color

Posted on Feb 06, 2026 by HunterLab

Every material absorbs, reflects, or transmits light, which determines the color we see when looking at an object. Transmission refers to the light waves that pass through a translucent or transparent sample, and spectrophotometers provide quantitative measurements of that data. These devices make it possible to evaluate a sample's color scientifically and objectively, which is vital for ensuring color consistency in various applications. Spectrophotometer transmittance measurements enable better quality control and enhanced consumer perception of your products.

What Is Transmittance in a Spectrophotometer?

The definition of transmittance is the measured light that passes through a sample, meaning the light that is not absorbed or reflected. Three primary transmittance measurements include:

Diffuse transmittance (Td, n): This measurement is the ratio of the flux transmitted by a specimen to the incident flux, with the transmitted flux being measured at all forward angles except the regular transmission angle. When light is diffusely transmitted, its direction changes as it passes through the material, causing scattering.
Regular transmittance (tr, n): This measurement is the ratio of undiffused transmitted flux to incident flux. In other words, it is straight-through light.
Total transmittance (tt, n): This measurement is the ratio of the flux transmitted at all forward angles to the incident flux. Total transmittance is the sum of regular transmittance and diffuse transmission.

These values are essential to maintaining quality in products like beverages and edible oils. It's best to measure color with a spectrophotometer to capture more accurate information, as these devices provide exact quantitative data regarding the amount of light that passes through a sample.

The transmittance formula is:

T = PT/P0

The values in this formula represent:

T: Transmittance
PT: The source's radiation power as it exits the sample
P0: The source's radiation power as it enters the sample

The resulting calculation is a ratio, comparing the light before it enters the sample to the light after it passes through it. A value closer to 1 means most light passes through, while lower values mean that less light passes through.

What Is Percent Transmittance in a Spectrophotometer?

Percent transmittance displays the light that passes through the sample as a percentage rather than the ratio created by the above formula. You can get the value by multiplying the ratio by 100.

A sample with 100% transmittance is transparent, allowing all light to pass through. Lower numbers indicate more translucence than transparency. At least 30% of the light must pass through the material for effective transmittance measurements.

The transmission percentage is also helpful for absorbance calculations. A commonly used absorbance formula is:

A = 2-log10(%T)

This formula determines the amount of light absorbed using the percentage of light that passes through the sample.

Interested in a little light reading?

"What Is the Best Way to Measure the Color of Citrus Juice?"

"What Is the Best Way to Measure the Color of Fruit Juices?"

"What Standard Do I Use to Verify Yellowness Index Performance?"

"When Is Sample Averaging Appropriate in Color Measurement?"

"Perfecting the Appearance of Light and Dark Rums Using Spectrophotometric Technology"

"6 Common Color Measurement Mistakes"

"Best Spectrophotometer for Measuring Transmittance Color"

What Is the Best Way to Measure the Color of Citrus Juice?

Use the Right Technique to Measure Citrus Liquids

Measure Your Liquid Samples With a Contactless Method

What Is the Best Way to Measure the Color of Fruit Juices?

Measure Fruit Juices Using the Right Equipment

What Standard Do I Use to Verify Yellowness Index Performance?

Materials That Require Yellowness Observations

What Is the Yellowness Index?

When Is Sample Averaging Appropriate in Color Measurement?

Perfecting the Appearance of Light and Dark Rums Using Spectrophotometric Technology

6 Common Color Measurement Mistakes

1. Relying on Subjective Descriptions and Visual Assessment

2. Not Using a Software Program

3. Not Considering Environmental Factors

Best Spectrophotometer for Measuring Transmittance Color

What Is Transmittance in a Spectrophotometer?

What Is Percent Transmittance in a Spectrophotometer?