analysis of glucose, fructose, and sucrose in jams pureesWhat does it take in terms of process analysis and control to manufacture jams, purees, and fruit juice from fresh, sweet summer fruits? Historically, wet chemistry methods have been been used to analyze raw materials and fruit juice products in a manufacturing setting, but this is a slow tedious process and for labs requiring a high turnover of samples is not efficient or timely.

At the J.M. Smuckers Co. in Orville, Ohio, preserves and jellies have been produced since the early 1920s and until a few years ago, their Discovery Lab used traditional wet chemistry methods to analyze glucose, fructose, and sucrose using this very slow process that did not provide their R&D department with timely results. In 2013, they modified their lab to include a discrete analysis system (Thermo Scientific Arena 20 Photometric Analyzer) and automated their test methods. Where it used to take up to one week to analyze just the sugars in fruit juice and purees, they could now analyze 50 samples in one hour and test for acetic, ascorbic, and citric acids in addition to the sugars.

What are they testing and why? Grape juice, in particular, is composed of 70-80% water, 20% carbohydrates, and 1% phenolics, vitamins, minerals, and nitrogenous compounds (link to page on extension.iastate.edu). Along with phenolics, sugars and organic acids provide the flavor. Sugars are a chemical subgroup of carbohydrates, taste sweet, and are water soluble and good sources of energy. Glucose and fructose are the most common sugars in grape juice, are responsible for its sweetness and will be consumed by yeast if fermentation is desired, e.g., in the production of wine. For more details on the lab solution, read more in this Case Study, titled, Benchmarks and Rapid Results for a Jam Producer (downloadable PDF).

By the way, sugar content in fruit juices is often examined to verify authenticity by using the ratio of fructose/glucose as specific natural sugar ratios exist for many fruits. In addition, sugar and acid levels are an indicator of the quality of fruit products. Simple enzymatic tests can be used with an automated discrete analysis system (either a Thermo Scientific Gallery Automated Photometric Analyzer or an Arena Photometric Analyzer). Common methods of determination can be accessed through AOAC Official Methods of Analysis 985.09 (19th edition) or International Federation of Fruit Juice Producers (IFU), Method numbers 52, 55, 56, 66 (1985-1996).

Our range of automated analyzers have test kits that can reliably measure the following sugars:

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  • D-Glucose
  • D-Fructose
  • D-Glucose + D-Fructose
  • D-Glucose + D-Fructose + Sucrose
  • Sucrose

They are optimized for use with the analyzers and have been developed for cost-efficient analysis and quality control while offering flexibility, speed, measurement accuracy, and precision. Standards are available to ensure that results are accurate and repeatable. In homogeneous juice samples, 100 samples can be analyzed for both glucose and fructose in 90 minutes with first results available in less than 15 minutes. Further savings can be realized as a result of reduced reagent usage and waste production; and, the cost is less than 20 cents per test.

Now that we have the jam, the only other necessary ingredient is peanut butter for a traditional American snack of peanut butter and jam on toast!

Additional Resources

More resources on this topic that may be of interest:

Are you measuring sugars in your fruit juice and puree samples and is automated photometric determination of interest to your laboratory? If so, we would like to hear about your experiences.

Liisa Otama is an International Application Specialist for Discrete Analyzers providing application support for food and beverage testing and water analysis in the Chromatography and Mass Spectrometry Division at Thermo Fisher Scientific, Inc. Her expertise is highly customer-focused and includes evaluating industrial product feedback and addressing inquiries, supporting customer training, and identifying new customer needs. Since 2008, she has held several positions ranging from process engineering to R&D. Liisa earned a B.Sc. in analytical chemistry from University of Helsinki, Finland, and has six publications and a patent to her credit.