Comparison of Automated Extraction Techniques for Volatile Analysis of Whole Milk Powder

Abstract

Volatile profiling of whole milk powder is valuable for obtaining information on product quality, adulteration, legislation, shelf life, and aroma. For routine analysis, automated solventless volatile extraction techniques are favored due their simplicity and versatility, however no single extraction technique can provide a complete volatile profile due to inherent chemical bias. This study was undertaken to compare and contrast the performance of headspace solid phase microextraction, thermal desorption, and HiSorb (a sorptive extraction technique in both headspace and direct immersion modes) for the volatile analysis of whole milk powder by gas chromatography mass spectrometry. Overall, 85 unique volatiles were recovered and identified, with 80 extracted and identified using a non-polar gas chromatography column, compared to 54 extracted, and identified using a polar gas chromatography column. The impact of salting out was minimal in comparison to gas chromatography column polarity and the differences between the extraction techniques. HiSorb extracted the most and greatest abundance of volatiles, but was heavily influenced by the number and volume of lactones extracted in comparison to the other techniques. HiSorb extracted significantly more volatiles by direct immersion than by headspace. The differences in volatile selectivity was evident between the techniques and highlights the importance of using multiple extraction techniques in order to obtain a more complete volatile profile. This study provides valuable information on the volatile composition of whole milk powder and on differences between extraction techniques under different conditions, which can be extrapolated to other food and beverages.

The Influence of Pasture and Non-pasture-Based Feeding Systems on the Aroma of Raw Bovine Milk

“…Bendall et al ( 13 ) also found an odour-active lactone (γ-dodec-cis-6,cis-9-dienolactone) present in milk derived from a TMR diet but absent in cows on a pasture diet. However, it appears that the extraction method can also have a significant impact on the recovery of many lactones ( 20 , 21 ) and that HS-SPME is not very suitable for the extraction of lactones (dependent upon fibre type), an extraction technique widely used for VOC analysis in bovine milk ( 27 , 28 , 31 , 40 ).…”

“…Other studies have also identified butanoic acid in bovine milk (1,13,16,27,28) although abundances were not statistically different in raw or pasteurised milk from these diets. The choice of the extraction method and the GC column used is likely to have a significant effect on the recovery of butanoic acid, as the recovery of acids is greatly influenced by the polarity of the sorbent and GC column (21). γ-Hexalactone is a lactone, with a coconut, fruity, sweet aroma and a medium odour threshold (45), but was described in this study as having a barbeque, caramel, tobacco, toasted, toffee aroma (as the odour was so diverse, it is possible that coelution may have occurred with another odour-active VOC that was below the limits of MS detection).…”

“…These appear to be more effective as direct immersive procedures rather than as headspace extraction procedures ( 20 ). A new version of sorptive extraction called high-capacity sorptive extraction (HiSorb) was successfully utilised by Faulkner et al ( 6 ) to profile VOC from bovine milk produced by different diets and outperformed HS-SPME in a study by Cheng et al ( 21 ) to profile VOC in whole milk powder. Thus, HiSorb as a direct immersion technique (DI-Hisorb) utilising polydimethylsiloxane (PDMS) as the sorbent appears ideally suited for GC-O analysis of bovine milk.…”

Volatile organic compounds in beef and pork by gas chromatography‐mass spectrometry: A review

“…Initially it was only available with PDMS but is now also available with PDMS/CWR, PDMS/DVB, and DVB/CWR/PDMS. Typical Hi‐Sorb applications include aromatics in coffee, lactones in milk, bacterial VOC in bodily fluids and esters in whisky [100], and whole milk powder [101], but no research has been carried out on meat to date.…”

Exploring the Volatiles Released from Roots of Wild and Domesticated Tomato Plants under Insect Attack

“…We trapped the root volatiles from the headspace in a compartmentalized setup using two different sorbent materials: polydimethylsiloxane (PDMS) in silicon-based tubes and commercial coated probes (HiSorb TM ). These materials have been reported to be widely used for passive sampling of volatiles from soil and roots [ 16 , 17 , 18 ]. Combining these two trapping methods, we compared the root volatilome of the domesticated tomato Solanum lycopersicum cv Moneymaker with that of its wild relative Solanum pimpinellifolium under attack of the leaf herbivore insect Spodoptera exigua .…”