Using Spectrophotometers to Meet the Color Standard for Canned Tomatoes


Posted on July 17, 2017

Genuine Italian food is known for its rich tomato-based sauces and homemade flavors, so I could not wait to taste and compare what this quaint little hole-in-the-wall had to offer. I was not disappointed! I always order ‘extra’ marinara sauce on the side to judge for quality and genuineness. When the vibrant red sauce appeared, the visual appeal did not disappoint. Appearance is one of the first criteria I use to base my opinion and just one taste had me sold!

Fresh tomato color and flavor are the keys to quality sauce, when paired with the right texture and flavor it is almost like a little taste of Italy right there on your fork. Although the restaurant owner would not share his secret recipe, he did provide a little tip that took me by surprise. He said that one of his tricks was choosing quality tomatoes…in a can! Did I hear that correctly? That bright red burst of flavor was just screaming ‘fresh tomatoes’, so of course I had to ask for the brand name. Now I can’t wait to try out my own recipe and perhaps fool some guests of my own with a canned version of ‘homemade’.

Starting with Raw Color Measurement

Superior canned tomato products start with a high standard of raw ingredients. Color is the main factor for determining quality in raw tomatoes and can be attributed to the presence of lycopene, which gives tomatoes their vibrant red color1. Lycopene is measured based on a color rating scale that utilizes instrumental analysis to create a colorimetric scoring system. Spectrophotometers are used to qualify color and create the measurements needed to relate product quality to a grading scale. This colorimetric scoring system has been developed through extensive research and analysis of tomato products at various stages of production to ensure color consistency and maturity. Advanced color measurement methods have revolutionized the tomato industry and lead to higher standards in all tomato-based products.

There have been various changes in the color measurement of tomato products over the years. Prior to 1972, all color acceptability ratings of raw tomato products were determined visually through the use of color discs to compare an acceptable minimum color standard. The USDA has now developed a new standard of measurement, with color tiles replacing the colored disc as the standard measurement tool. These tiles can also be used to classify tomato color for grade development visually, but variations in individual color perception and the amount of time consumed by this process has now made this process nearly obsolete.

Tomato Grading and Color Analysis

 Like many agricultural products, canned tomatoes are subject to a grading system, which is regulated by USDA standards. Meeting specific criteria for these standards requires the use of instrumental analysis for color determination and variations in product appearance. “Minimum Red” for canned tomatoes is the minimum color acceptable for U.S. Grade C2. Determination of minimum red color is based on a comparison of the blended tomato mixture with the Munsell color system for tomato products to ensure color quality. Spectrophotometers quantify color numerically for the most accurate and efficient system of comparison.

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