This document summarizes an experiment analyzing organic acids in cheese using HPLC methods. Key findings include: - Lactic acid is the main acid present in cheeses tested (American, Parmesan, American Cheddar). Its concentration can be attributed to ripening during storage. - Butyric acid concentrations were too small to detect in the cheeses. - American cheese had the highest lactic acid concentration, while American Cheddar had the lowest. - The method achieved good resolution of peaks using a temperature of 60°C and a cation exchange column, allowing consistent analysis of lactic, acetic, butyric and pyruvic acids.

1. Determination of Organic Acids in Cheese by HPLC Methods Holy Cross Analytical Lab II Andre Isaacs Dan Dowling

7. Calibration Data

8. Linear Regression Coefficients and Detection Limits for method 0.000405 0.9993 Pyruvic 0.003454 0.9996 Butyric Acid 0.00529 0.9995 Acetic Acid 0.006425 0.9993 Lactic Acid Detection limit R 2 Organic Acid

9. Sample Chromatogram: Parmesan Cheese

10. Organic Acids Data 6 Pyruvic 7 Lactic 11.2 Butyric 8.1 Acetic Ret. Time (min) Acid 0.0001 ± 0.0001 0.0005 ± 0.0001 0.0004 ± 0.0001 Pyruvic -0.001 ±0.006 -0.003 ± 0.002 0.00 ±0.01 Butyric 0.004 ± 0.003 0.002 ± 0.003 0.009 ± 0.003 Acetic 0.0939 ± 0.0002 0.054 ± 0.004 0.048 ± 0.004 Lactic American Cheese (M) Parmesan (M) American Cheddar (M) Acids

11. Literature Comparison 1 Zeppa, G., COnterno, L., Gerbi, V.: Determination of Organic Acids, Sugars, Diacetyl, and Acetoin in Cheese by High-Performance Liquid Chromatography . J. Agric. Food Chem. 2001 , 49, 2722-2726 0.035 0.18 Pyruvic Acid 0.54 2.96 Acetic Acid 4.3 62.01 Lactic Acid Experimental conc. (American Cheddar) (g/kg) Literature conc. (Ossolano Cheese) (g/kg) 1 Organic Acid