Protein, Fat, and Total Solids Analysis of Cultured Dairy Beverages

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Cultured dairy products have seen a strong resurgence over the last decade, which started with an increase in popularity of Greek yogurt. Greek yogurt is high in protein and is generally perceived as a very healthy food. As the popularity in cultured dairy products continues to evolve, the demand for Kefir and other dairy-based beverages has grown significantly in the last few years. Kefir is a cultured dairy beverage that is high in protein and is easy to consume on-the-go. High and low fat options are available with fruit flavors being the most popular. Traditionally, fat testing for cultured dairy products has been performed using gravimetric extraction, which is time consuming, demands skilled technicians, and requires hazardous solvents. Various rapid techniques (TD-NMR, NIR, FT-IR, and FT-NIR) have been introduced, each with their own shortcomings, due to the need for extensive calibration development and maintenance. Protein determination has traditionally been accomplished with Kjeldahl titration, which is similarly time-consuming, requires hazardous chemicals, and is an indirect method that equates total nitrogen with protein levels.

The Sprint is a dye-binding technique that measures proteins directly instead of total nitrogen, avoiding error due to the presence of nitrogen in flavorings or additives. The ORACLE is a rapid time domain NMR (TD-NMR) instrument incorporating proprietary technology that allows for direct determination of fat in any dairy sample. Unlike other rapid techniques, the ORACLE is able to completely isolate the detection of fat in complex matrices, eliminating the need for calibration. To achieve both rapid moisture/solids and fat testing, the ORACLE can be coupled with a SMART 6 moisture/solids analyzer.

To demonstrate the ability of the Sprint, ORACLE, and SMART 6 to accurately and reliably determine the protein, fat and total solids in cultured dairy samples, an assortment of five samples were obtained and analyzed. The samples were selected to represent a range of protein and fat concentrations.