71A-6 |
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N. KOCA, L. Rodriguez-Saona, W. J. Harper, and V. B. Alvarez. Dept. of Food Science and Technology, The Ohio State Univ., 2015 Fyffe Ct., 110 Parker Food Science Bldg., Columbus, OH 43210-1007 Short-chain free fatty acids (FFA) are important sources of cheese flavor and have been reported as indicators for assessing ripening time and quality. The possibilities of predicting the quality of cheese during maturation by means of a few selected variables can save time and money to the cheese-maker. Infrared spectroscopy is an attractive technology for the rapid, inexpensive, sensitive, and high-throughput analysis of food components without requiring special skills from the users. The objective of this research was to develop a simple and rapid screening tool for monitoring short-chain FFA contents in Swiss cheese by using FT-IR spectroscopy. Different sampling approaches were evaluated: (1) Swiss cheeses infiltrated, under vacuum, with different levels of propionic acid (2 mg/1g to 6 mg/1g); (2) Commercial Swiss cheese samples at different ripening ages (1.5, 14, and 33 mo); and (3) Swiss cheeses (16) obtained from a local market. Direct measurements of Swiss cheese slices were made by using an infrared spectrometer equipped with a MIRacle three reflection diamond attenuated total reflectance (ATR) accessory. The FFA (propionic, acetic, and butyric acids) contents in water extract of samples were analyzed by GC-FID as a reference method. Partial least squares (PLS) regression was used to create calibration models that were cross-validated (leave-one-out approach). Infrared spectroscopy and chemometrics accurately and precisely predicted the FFA content in Swiss cheeses. PLS models generated from FT-IR/ATR spectra of cheeses gave standard error of prediction (SEP) < 17mg/100g for propionic, < 9 mg/100g for acetic, and < 7 mg/100g for butyric acids and R2 > 97%. FT-IR/ATR spectroscopy allowed for the rapid (~3 min analysis time) and accurate analysis of FFAs in Swiss cheeses. This technique could contribute to the development of simple and rapid protocols for monitoring the complex biochemical changes occurring during cheese ripening and predicting the final quality of the cheeses.
Session 71A, Dairy Foods: General
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |