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Spectrometers or spectrophotometers are valuable tools companies use to ensure the quality and consistency of the products they make and sell. They can tell us if the oil is contaminated or if the fruit is ripe. They ensure that your favorite tomato ketchup is the same red, batch to batch. They provide the safety and efficacy of the medications you take. They are a valuable tool to ensure corporate brand integrity and that consistency and performance remain intact across an entire warehouse of products. To understand how spectrophotometers work, we need to comprehend the science of spectrophotometry.
Spectrophotometry is the science of how light interacts with matter. The objects we see daily are different forms of matter – solids, liquids, and gases. You may be surprised to learn that matter does not possess color. An apple appears red because of how light interacts with the chemical composition of the apple. When light strikes matter, some wavelengths are absorbed, and some are emitted. We see and perceive the emitted light as ‘color.’
Spectrophotometers mimic this visual observing condition, providing information about the color of materials that is meaningful and actionable, allowing companies to ensure color accuracy and consistency across their range of products and brand colors.
So, how does all this happen from a spectrophotometer, and how do we use it? The science behind this tool is robust and can be utilized in several different ways. To clarify, we’ve gathered information on how spectrophotometers contribute to the color management of various products and technologies, so let’s dive in.
What Is a Spectrophotometer?
You may remember from chemistry class that light is a form of electromagnetic radiation, like microwaves and gamma rays. When we talk about the spectrum of light, we’re talking about a spectrum of energy, where different energy levels create what we perceive as other colors. The colors of the rainbow follow the progression of visible energy, with red being the lowest and violet being the highest. Materials that absorb all visible light appear black, while those that do the opposite appear white. In between those two are materials that emit certain light energies and absorb others, displaying specific colors.
A spectrophotometer is essentially a calibrated light counter.
“Spectro” refers to the fact that light is dispersed into individual wavelengths in the electromagnetic energy spectrum. Some of that energy is in the ultraviolet and visible spectrum, which spectrophotometers can read, while other spectrometers can measure infrared radiation.
“Photometer” measures light intensity at specific wavelengths and is scaled from 0 to 100. Zero equals total darkness, and 100 is perfect white. Some properties, like fluorescence, make it possible for this scale to go over 100, so most spectrophotometers can reach 150 or 200.
Spectrophotometers are used to measure the color of materials. Materials can be solid, liquid, opaque, translucent, or transparent. Different methods are used to measure these materials, depending on their form and transparency. Opaque materials are measured using reflectance spectrophotometers, which measure the amount of light reflected from a sample. In contrast, transparent materials use transmission spectrophotometers, which measure the amount of light that passes through the material. Regardless of the method used, all spectrophotometers share the same basic technology and optical design:
A controlled light source to illuminate the material.
A lens to collimate the light to the monochromator.
A monochromator that separates the light into its constituent color wavelengths.
A wavelength selector.
A detector that quantifies the light emitted from the sample.
Loose powders present several color measurement challenges, from nonuniform samples to light interference. These challenges exist across everything from powdered chemicals to cocoa and baking powder. The ColorFlex L2 overcomes all the challenges of powder color measurement, offering an easy-to-use design and high-quality results.
The Difficulties of Powder Color Measurement
Understanding the challenges faced in color measurement enables you to address them more effectively. Here are the most common issues in collecting spectral data for powders:
Nonuniformity: Powders consist of tiny particles that appear differently depending on how they are prepared.
Light sensitivity: Powders cause light trapping, shadowing, and ambient light interference, which can result in inaccurate measurements.
Sample size: Powders often consist of a small amount of material, but the sample must be thick enough to create an opaque layer.
Fluorescence: Powders are sometimes affected by UV light, which influences their measurement results without adequate controls.
Spice color measurement presents several challenges, from controlling costs for more expensive spices to maintaining effective quality control procedures. The ColorFlex L2 from HunterLab easily addresses these and other measurement difficulties, reducing wastage and ensuring accuracy.
The Challenges of Spice Color Control
Spice color control comes with several unique hurdles, including:
Meeting industry-standard control regulations, such as those from the American Spice Trade Association (ASTA)
Measuring color as it changes throughout stages of production and considering the influence of maturity on color
Managing costs in spectral data measurement, especially for more expensive spice varieties
Maintaining quality control by identifying variations that could indicate compromised food safety
How the ColorFlex L2 Helps
The ColorFlex L2 is a durable, reliable color measurement solution that takes up minimal space on your benchtop. It works on everything from powders to granules, making it ideal for measuring spices throughout various stages of production. This solution includes all scales and indexes in the food industry, including ASTA.
It enables you to control costs, even for expensive spice varieties, by measuring small samples and reducing the wastage of end products. You can even export your results to monitor data and safety over time.
Consumers of food products like tomato paste judge their quality by their color. Appearance relates to freshness and taste, so buyers prefer a product with a standardized, consistent appearance. Following best practices in color measurement allows tomato paste producers to create a product that appeals to customers, influencing sales.
Consider Factors Influencing Color
Before measuring color, determine the factors that influence it. The ripeness of the tomatoes impacts appearance, as the amount of lycopene increases as tomatoes ripen to create a more vibrant red. Other factors, like production methods and storage conditions, lead to variations such as brown or muted hues. Knowing these factors enables producers to adjust their processes based on the measurement results.
Color is a critical quality component for spices like paprika. The American Spice Trade Association (ASTA) has sampling and measurement standards for paprika, and a spectrophotometer from HunterLab effectively quantifies paprika color values for quality assurance.
How Paprika and Oleoresin Spices Are Made
Paprika is obtained from the ripened, ground, and dried fruit pods of the Capsicum annuum species. The Capsicum annuum peppers used for paprika are sweet and mild with little to no capsaicin, which is a heat compound.
The Capsicum annuum plant is grown until its peppers are mature and have ripened to a red color. The fully ripened peppers are picked for paprika to give the spice its signature red color. The pepper seeds are removed, and the fruit pods are dried in the sun or specially constructed dryers. After drying, producers grind peppers into powder.
Oleoresin paprika — or paprika extract — is the oil-soluble extract obtained by extracting lipids and pigments from Capsicum annuum linn or Capsicum frutescens fruits. The oleoresin comprises capsaicin, capsanthin, and capsorubin, giving the product a strong taste and odor. Oleoresin paprika is a natural dye that colors foods a deep red hue.
While cocoa powder isn't consumed on its own, it flavors and colors many chocolate-based recipes, from brownies to bundt cakes. To ensure their baked goods turn out the way they intend, consumers often judge cocoa powder based on its appearance alone — sometimes subconsciously — to determine its quality.
As a cocoa powder producer, your primary goal is to assure customers that your cocoa powder is the best choice for their recipes. One way to do that is by measuring the color of your cocoa powder at each stage.
Analyzing loose powder hues comes with unique challenges due to the innate qualities of the powders.
Spring is a time of rebirth and regeneration when color returns to our world vividly after the grays and whites of winter. And perhaps there is no better expression of this than the Hindu celebration of Holi, also known as the festival of colors.
Each spring, people around the world — Hindu, and non-Hindu alike — mark the coming of the season in a brilliant display of colorful powders thrown in the air and streaked across revelers. This colored powder is essential to the celebrations, originating with the legend of the Hindu deity Krishna who colored his lover’s face to match his own blue skin.
Today, four primary powder colors are used during the festival, each representing a unique aspect of the Holi celebration. Green signifies spring's new beginnings, blue symbolizes the connection to Krishna, red stands for fertility and love, and yellow evokes health and happiness.
Traditionally, these hues were created using real turmeric, flower extracts, and sandalwood paste. Now, however, they are largely produced using artificial colorants. This practice has led to health and environmental concerns after reports that hazardous materials like chromium and lead were used in powder production. These chemicals can cause pollution and health issues like eye and skin irritation or respiratory illnesses.
As a result, a number of commercial powder suppliers have recently returned to more natural and plant-based color sources. In order to promote safer, more eco-friendly products, however, powder suppliers must ensure that their powders accurately reproduce the vivacious colors we have become accustomed to. This is vital in order to allow customers to obtain healthier products without compromising appearance. This requires careful monitoring of color behavior throughout the production process.
Reflectance spectrophotometers are ideal for measuring the color of all types of loose powders, regardless of their end use. Using a 45°/0° geometry, these spectrophotometers mimic the way the human eye sees color, only better. Without the impact of outside interferences, spectrophotometric devices are able to objectively analyze samples for the highest level of accuracy and repeatability. As such, they serve a critical role in the development and production of loose powders across industries, from cosmetics to pharmaceuticals. However, there are a number of special considerations for loose powder color measurement that must be kept in mind during the analytical process.
