Solid phase microextraction and gas chromatography-mass spectrometry (SPME-GC-MS) are commonly used for qualitative and quantitative analysis of volatile compounds in various dairy products, but conditions have to be adjusted to maximize release while not generating new compounds that are absent in the original sample. Queso Fresco, a fresh non-melting cheese, may be heated at 60 °C for 30 min; in contrast, compounds are produced in milk when exposed to light and elevated temperatures, so milk samples are heated as little as possible. Products such as dehydrated whey protein are more stable and can be exposed to longer periods (60 min) of warming at lower temperature (40 °C) without decomposition, allowing for capture and analysis of many minor components. The techniques for determining the volatiles in dairy products by SPME and GC-MS have to be optimized to produce reliable results with minimal modifications and analysis times.
References
[1]
Fox, P.F.; Guinee, T.P.; Cogan, T.M.; McSweeney, P.L.H. Fundamentals of Cheese Science; Springer: Gaithersburg, MD, USA, 2000; pp. 31–39.
[2]
Tunick, M.H. Whey Production and Utilization: A Brief History. In Whey Processing, Functionality and Health Benefits; Onwulata, C.I., Huth, P.J., Eds.; Wiley-Blackwell: New York, NY, USA, 2008; pp. 1–13.
[3]
Kataoka, H.; Lord, H.L.; Pawliszyn, J. Applications of solid-phase microextraction in food analysis. J. Chromatogr. A 2000, 880, 35–62, doi:10.1016/S0021-9673(00)00309-5.
[4]
Arthur, C.L.; Pawliszyn, J. Solid phase microextraction with thermal desorption using fused silica optical fibers. Anal. Chem. 1990, 62, 2145–2148, doi:10.1021/ac00218a019.
[5]
Zhang, Z.; Yang, M.J.; Pawliszyn, J. Solid-phase microextraction. A solvent-free alternative for sample preparation. Anal. Chem. 1994, 66, 844A–853A.
[6]
Marsili, R.T. SPME-MS-MVA as an electronic nose for the study of off-flavors in milk. J. Agric. Food Chem. 1999, 47, 648–654, doi:10.1021/jf9807925.
[7]
Chin, H.W.; Bernhard, R.A.; Rosenberg, M. Solid phase microextraction for cheese volatile compound analysis. J. Food Sci. 1996, 61, 1118–1122.
[8]
Quach, M.L.; Chen, X.D.; Stevenson, R.J. Headspace sampling of whey protein concentrate solutions using solid-phase microextraction. Food Res. Int. 1999, 31, 371–379.
[9]
McGorrin, R.J. Flavor Analysis of Dairy Products. In Flavor of Dairy Products; Cadwallader, K.R., Drake, M.A., McGorrin, R.J., Eds.; ACS Books: Washington, DC, USA, 2007; pp. 23–49.
[10]
Guo, L.; Van Hekken, D.L.; Tomasula, P.M.; Shieh, J.; Tunick, M.H. Effect of salt on the chemical, functional, and rheological properties of Queso Fresco during storage. Int. Dairy J. 2011, 21, 352–357, doi:10.1016/j.idairyj.2010.12.009.
[11]
Marsili, R.T. Flavours and Off-Flavours in Dairy Foods. In Encyclopedia of Dairy Sciences; Roginski, H., Fuquay, J.W., Fox, P.F., Eds.; Academic Press: San Diego, CA, USA, 2003; pp. 1069–1081.
[12]
Hettinga, K.A.; van Valenberg, H.J.F.; van Hooijdonk, A.C.M. Quality control of raw cows’ milk by headspace analysis. Int. Dairy J. 2008, 18, 506–513, doi:10.1016/j.idairyj.2007.10.005.
[13]
Valero, E.; Sanz, J.; Martinez Castro, I. Volatile components in microwave- and conventionally-heated milk. Food Chem. 1999, 66, 333–338.
[14]
Croissant, A.E.; Washburn, S.P.; Dean, L.L.; Drake, M.A. Chemical properties and consumer perception of fluid milk from conventional and pasture-based production systems. J. Dairy Sci. 2007, 90, 4942–4953, doi:10.3168/jds.2007-0456.
[15]
Mariaca, R.G.; Berger, T.F.H.; Gauch, R.; Imhof, M.I.; Jeangros, B.; Bosset, J.O. Occurrence of volatile mono- and sesquiterpenoids in highland and lowland plant species as possible precursors for flavor compounds in milk and dairy products. J. Agric. Food Chem. 1997, 45, 4423–4434.
[16]
Grova, N.; Feidt, C.; Crépineau, C.; Laurent, C.; Lafargue, P.E.; Hachimi, A.; Rychen, G. Detection of polycyclic aromatic hydrocarbon levels in milk collected near potential contamination sources. J. Agric. Food Chem. 2002, 50, 4640–4642.
[17]
Contarini, G.; Povolo, M. Volatile fraction of milk: Comparison between purge and trap and solid phase microextraction techniques. J. Agric. Food Chem. 2002, 50, 7350–7355, doi:10.1021/jf025713a.
[18]
Vazquez-Landaverde, P.A.; Velazques, G.; Torres, J.A.; Qian, M.C. Quantitative determination of thermally derived off-flavor compounds in milk using solid-phase microextraction and gas chromatography. J. Dairy Sci. 2005, 88, 3764–3772, doi:10.3168/jds.S0022-0302(05)73062-9.
[19]
Le Quéré, J.-L.; Molimard, P. Cheese Flavour. In Encyclopedia of Dairy Sciences; Roginski, H., Fuquay, J.W., Fox, P.F., Eds.; Academic Press: San Diego, CA, USA, 2003; pp. 330–340.
[20]
Milo, C.; Reineccius, G.A. Identification and quantification of potent odorants in regular-fat and low-fat mild Cheddar cheese. J. Agric. Food Chem. 1997, 45, 3590–3594, doi:10.1021/jf970152m.
[21]
Frank, D.C.; Owen, C.M.; Patterson, J. Solid phase microextraction (SPME) combined with gas-chromatography and olfactometry-mass spectrometry for characterization of cheese aroma compounds. Lebens. Wiss. Technol. 2004, 37, 139–154, doi:10.1016/S0023-6438(03)00144-0.
[22]
Burbank, H.M.; Qian, M.C. Volatile sulfur compounds in Cheddar cheese determined by headspace solid-phase microextraction and gas chromatograph-pulsed flame photometric detection. J. Chromatogr. A 2005, 1066, 149–157.
[23]
Pérès, C.; Viallon, C.; Berdagué, J.-L. Solid-phase microextraction-mass spectrometry: A new approach to the rapid characterization of cheeses. Anal. Chem. 2001, 73, 1030–1036.
[24]
Wright, B.J.; Sevchak, S.E.; Wright, J.M.; Drake, M.A. The impact of agglomeration and storage on flavor and flavor stability of whey protein concentrate 80% and whey protein isolate. J. Food Sci. 2009, 74, S17–S29, doi:10.1111/j.1750-3841.2008.00975.x.
[25]
Farrell, H.M., Jr.; Jimenez-Flores, R.; Bleck, G.T.; Brown, E.M.; Butler, J.E.; Creamer, L.K.; Hicks, C.L.; Hollar, C.M.; Ng-Kwai-Hang, K.F.; Swaisgood, H.E. Nomenclature of the proteins of cows’ milk—Sixth revision. J. Dairy Sci. 2004, 87, 1641–1674.
[26]
Carunchia Whetstine, M.E.; Croissant, A.E.; Drake, M.A. Characterization of dried whey protein concentrate and isolate flavor. J. Dairy Sci. 2005, 88, 3826–3889, doi:10.3168/jds.S0022-0302(05)73068-X.
