Spectral Analysis of Peanut Butter: The Multiple Uses of Color Measurement in Nut Products

Peanuts are a major agricultural crop all around the world. Nearly 50% of all shelled peanut products in the United States are processed into peanut butter, and development of this popular commodity depends on spectral analysis for the best visual quality and taste. Perhaps it is already apparent how color measurement would affect the appearance of peanut butter products, but maybe even more important is how the color of roasted peanuts correlates with flavor.

bowl of peanuts in shells spectral analysis
Peanuts are a major agricultural product around the globe. From shelled, to roasted, to crushed and pureed, peanuts are a great snack food and used in many other food products as well.
Image Source: Flickr user USDAgov

Spectral analysis refers to the use of light to differentiate the color in various sample materials and quantify this data for quality analysis or reproduction purposes. This process is extremely important when dealing with food products that require multiple stages of preparation, especially products which are roasted during the processing phase. Spectral analysis during roasting of products, such as coffee beans, helps to determine the final color result and also helps to determine the flavor outcome. This is also true in roasting peanuts. No matter what peanut variety is used, common roasting practices and overall color measurement stability will help ensure a quality product that meets the standards in both appearance and taste.

Spectral analysis during the peanut roasting process

Spectrophotometers are a common tool used for color measurement in peanut butter production. There are many steps to producing commercial peanut butter, beginning first with the cleaning and shelling the raw peanuts and then removing the skin through mechanical processing and heat. This step is crucial in final color development, since the reddish hues of the skin pigmentation can drastically alter the final color of the product. Once the skins are removed and the peanut seeds are split, the embryo (germ) is removed. At this point the nuts are either dry oven roasted or roasted in oil. This process is used to destroy the enzymes that could cause off flavors from oil to break down, and to change the product color to the desired shade and hue for marketability.

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shelled peanuts spectral analysis
Shelled peanuts undergo a series of processes in preparation for use as peanut butter. Proper roasting color can be monitored with spectrophotometers and this data can be used to determine both final color and flavor of the peanut butter.
Image Source: Flickr user Daniella Segura

With flavor so closely linked to color, the use of spectral analysis to monitor color changes throughout the roasting process is essential for creating a quality product. By continually monitoring color changes using spectrophotometric technology during the roasting process, even slight changes can be detected and alterations to the roasting process can be made in real-time. This ensures consistency from batch to batch, as well as creating a determination of final flavor outcome as well as color.

Peanut butter color regulations and standardization

Not only does peanut color affect the final quality and taste of peanut butter, but strict regulations govern the production of peanut butter in the U.S. These regulations refer to color specifications that are dependent on spectral analysis through the use of spectrophotometric instrumentation. The USDA (United States Department of Agriculture) focuses on the importance of color for is grading policies as follows:

SUGGESTED ORDER FOR ON-LINE GRADING OF A SAMPLE UNIT

  • Evaluate each sample unit for flavor and odor. Evaluate the flavor and odor quickly, as soon as the container is opened. The first impression is the best because the taste and smell sensations are quickly satisfied. Often, further flavor and odor evaluations of the sample fail to give reliable results. Good flavor is the result of properly roasted peanuts (neither under roasted nor over roasted) blended with the right proportion of additives (salt, sugar, honey, dextrose, etc.) for the particular type, style, and texture of peanut butter being produced. Good flavor in light brown, non-stabilized, medium texture “old fashioned” peanut butter cannot be used as a guide for evaluating the flavor of a dark brown, stabilized, smooth texture peanut butter containing all the permitted additives. The flavor should be evaluated based on the ideal for the particular style, type, and texture. The degree of roast has a great influence on flavor, odor and color. Peanut butter with good color could be expected to have better flavor than peanut butter with less than good color. The aroma of peanut butter should be that of freshly roasted and ground peanuts. The aroma must be free from musty, rancid, moldy, or any other objectionable odor.

In the USDA’s specific grading policies, sections §52.3066 and §52.3068, color is specifically referred to again.  Even the FDA (Food and Drug Administration) specifically mentions color as a major factor and requirement for federal food safety regulations.

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Not only can spectral analysis help identify slight color variations; it can also be used to measure other food product components, such as protein and sugar content. Spectrophotometers provide a highly versatile tool to food production manufactures, as well as multiple forms of analysis.

peanut butter spectral analysis
Many government standards set regulations on peanut butter quality. Creating the desired color outcome of peanut butter products can easily be obtained through spectral analysis.
Image Source: Flickr user Brad Topar

Spectrophotometers in the peanut industry

Spectrophotometers are a common production tool for many of the major peanut processing manufactures around the globe. Many leading peanut butter producers understand the importance of spectral analysis throughout the roasting process and in the final evaluation of peanut-based products. HunterLab is an industry leader in spectrophotometric technology and maintains a large presence in the food manufacturing industry. Peanut processing is on the forefront of our spectral analysis instrumentation design, and the D25NC is our latest addition to this line of equipment specifically designed for peanut product measurement. We understand the challenges of spectral analysis in peanut products and work hard to meet those needs in our product design. For more information on spectral analysis and color measurement of peanut products and peanut butter, contact HunterLab today.

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