Characterization of Volatile Compounds in Microfiltered Pasteurized Milk Using Solid-Phase Microextraction and GC×GC-TOFMS

Abstract

Volatiles of milk were characterized by solid-phase microextraction coupled with comprehensive twodimensional gas chromatography and time-of-flight mass spectrometry. Comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry two-dimensional gas chromatography with time-of-flight mass spectrometry not only separated the 52 compounds that co-elute in conventional gas chromatography-mass spectrometry, but also identified 107 compounds that were first reported in milk. These volatiles included aliphatic hydrocarbons (69), aromatic hydrocarbons (42), ketones (28), esters (16), aldehydes (14), alcohols (14), acids (14), nitrogenous compounds (9), ethers (8), and sulfo compounds (3). Five dominant volatiles were hexanoic acid (193.57 ng/mL milk), methoxy-phenyl-oxime (114.83 ng/mL milk), octanoic acid (109.38 ng/mL milk), 4,5-dimethyl-1hexene (101.48 ng/mL milk), and 2-Pentanone (99.74 ng/mL milk). This proposes an improvement methodology for determining the volatiles of dairy products.

Characterization of volatile compounds and organic acids in ultra-high-temperature milk packaged in tetra brik cartons

“…Similarly, Vegas and Roussis [13] reported an increase in butanoic, hexanoic, octanoic, and decanoic acids in pasteurized milk compared to raw cow milk. Acids identified in this study have previously been found in milk pasteurized by microfiltration and ultrapasteurized milk with dominance of hexanoic and octanoic acids, respectively, [18,29,44] who indicated that pasteurization with microfiltration caused a greater increase in acids than pasteurization only. Although the fat content of commercial UHT milk samples analyzed is standardized to values of ≤3% and <3.5% as UHT whole milk, the values of free fatty acids showed a wide variation from brand to brand, ranging from 25.78 to 87.96%.…”

“…There is little information on oxime-methoxy phenyl. This compound has previously been found in micro-filtered pasteurized milk as dominant VOC, [18] and also in ultrapasteurized milk packaged in polyethylene terephthalate containers [29] and reconstituted milk. [44] Oximes are may be formed by reaction aldehydes or ketones with a nitrogen-containing reducing agent in a weakly acidic medium during the high heat treatment and/or homogenization since aldehydes were detected in UHT milk samples at trace levels and samples with low ketone percentages had a high level of oxime-methoxy phenyl.…”

“…This could be attributed to the different process technology, quality of initial raw milk and the high storage temperatures since the contents of free fatty acid are increased in UHT milk produced from the raw material with the largest number of psychrotrophic bacteria and stored at the high temperatures [54] and also in milk pasteurized by microfiltration. [18,29,44] Although ethanol was found in all the samples at trace levels, 2-furan methanol, 2-pentanol, and 2-ethyl-1-hexanol were determined in some UHT milk samples as the major alcohols. These alcohols may be formed by the reduction of aldehydes, were previously identified in milk powder.…”

“…[16] SPME-gas chromatography-mass spectrometry (GC/MS) technique has been used in analysis of volatiles of milk. [4,13,17,18] In the present study, we sampled the UHT milks with the similar expiration date and fat content in order to elimination the effects of storage period and fat content on VCs. Therefore, we aimed to determine the changes in VCs and OA contents in the UHT milk samples with the similar basic nutrient components, packing materials, and the expiration date.…”

Dietary Compounds Influencing the Sensorial, Volatile and Phytochemical Properties of Bovine Milk

“…It is possible that the furan 2,4-dimethylfuran (odor unknown) in the milk samples is due to the thermal degradation of certain amino acids, including serine and cysteine [52]. Further, 1,3-Bis(1,1-dimethylethyl)-benzene (odor unknown), 2,4-dimethyl-benzaldehyde (naphthyl), and tert-butylbenzene (phenolic) could have entered the milk through inhalation or ingestion, and were possibly partially degraded to phenol (phenolic) [53], however, some benzene compounds are thought to be products of the Strecker reaction [54]. For example, p-Xylene (sweet) may be present as a result of β-carotene degradation in the rumen [55], or from direct transfer from feed [56].…”