The Color of Flour: Evaluating Grain Products with Spectral Analysis

Spectral analysis plays an important role in the evaluation of baked goods and raw materials and can measure the uniformity and quality of these products. Image Source: Flickr user Shimelle Laine

Flour is a staple that serves as the foundation for many baked goods and products. Many of these baked goods rely on spectral analysis to maintain uniform color. Controlling the color of the raw materials that are used in the production of baked goods is the first step towards consistency and uniformity. Since even slight variations in color can have a major overall effect, this uniformity is of the utmost importance to the finished product.

Flour production is a complex process that requires many steps of analysis. Spectrophotometers are often used to analyze flour color in addition to other key elements of flour. Flour is a biological product, so the raw materials that constitute it often come from a variety of sources. When manufacturing and developing flour, these raw materials can vary greatly and must be evaluated for protein quality and quantity, moisture level, ash content, color, and other physical properties. Spectral analysis provides an effective and efficient method of measurement for many of these properties; so much so, that the analysis of every property can be achieved with one simple tool: the spectrophotometer.

Color testing and quality

Color is an important factor in flour quality and relies on both human vision analysis and instrumental evaluation. Spectral analysis plays an important role in quantifying color for flour quality approval. The book Engineering Aspects of Cereal and Cereal Based Products states: “color testing of wheat flour is done for the purpose of evaluating its whiteness, which determines the extent of oxidization of carotenoid pigments by bleaching agents, or the presence of bran particles…[Color measurement instruments] provide a quantitative measurement and are widely used to monitor the color of flour.”

Spectrophotometers measure whiteness in flour to determine both purity and product quality.

Image Source: Flickr user david pacey

Spectral analysis of flour is an important step in monitoring the color of the final product. Various pigments and particles directly affect color changes and outcomes in baked goods, so they must be carefully evaluated for color consistencies and uniformity. Spectral analysis is an approved method of color quantification and can be used to determine many of the other properties of flour and baked goods.

Other applications for spectral analysis

The American Association of Cereal Chemists (AACC) has published a list of approved analytical methods for monitoring the consistency of different properties of flour and baked goods. In addition to color quality and whiteness, there are three other main properties of flour that require instrumental evaluation:

• Moisture Content: this analysis measures the amount of dry solids in the product. Specifications typically limit moisture content to 14% or less and many millers use this percentage as a standard for their product so that they can optimize shelf-life and flour quality. Anything over 14% allows for the growth of naturally occurring organisms and can create on unpleasant odor or off taste.
• Protein Levels: Protein levels in flour often correlate to their performance in baked goods. Given that, whether or not the level of protein in flour is measured properly can have a drastic impact on the finished product. Higher levels of protein are often more desirable in bread products and very low protein levels produce better results in cakes and pastries. Quality flours depend on the precise quantification of these protein levels, which can directly affect the prices of these flour products.
• Ash Content: Ash content refers to the mineral levels found in flour. Traditional methods for determination of ash involve the lengthy process of incineration and weight measurements. The information provided from ash content analysis measures the percentage of endosperm and purity in the flour product.

There are many properties that affect the quality of flour. Spectral analysis offers a simple and non-destructive method of evaluations in both raw materials and finish products.

Image Source: Flickr user U.S. Department of Agriculture

In addition to color quality, spectral analysis can also be used to quantify all three of these major properties in flour. NIR (near-infrared) spectrophotometry measures light reflectance values, which can provide a wealth of information for flour analysis. Brightly colored or higher-level reflectance value measurements correlate with lower levels of ash. Therefore, brightness levels are often used to determine the purity and quality of flour. Protein and moisture content can also be determined through spectral analysis. Traditional methods of protein analysis are time-consuming and involve the use of toxic chemicals. Spectral analysis offers a safe and non-destructive method of determining protein levels.

From flour analysis to finished product

Spectral analysis is a reliable and efficient method of analyzing the various properties of flour and determining the final color outcome in baked goods. Advancements in spectrophotometry have created a highly versatile tool that can be used for many applications. From raw flour materials to finished baked good products, color measurement plays a vital role in quality and consistency. HunterLab is an industry leader in spectrophotometric technology, and we specialize in baked good production and evaluation. For more information about our instrumentation options or to learn more about spectrophotometric applications in grain products, contact HunterLab today.