Comparison of Four Extraction Techniques for the Evaluation of Volatile Compounds in Spray-Dried New Zealand Sheep Milk

Abstract

Recent growth and diversification of sheep milk products means more sophisticated methods are required to ensure their flavour quality. The objective of this study was to compare four extraction techniques for the analysis of volatile compounds in sheep milk by gas chromatography-mass spectrometry (GC-MS). Solvent Assisted Flavour Evaporation (SAFE), Solid Phase Microextraction (SPME), Headspace Sorptive Extraction (HSSE) and Stir Bar Sorptive Extraction (SBSE) were evaluated for their sensitivity, selectivity, reproducibility, and overall efficiency. A total of 48 volatile compounds from nine compound classes were identified in the spray-dried sheep milk. Alcohols, aldehydes, alkanes, carboxylic acids, ketones, lactones, sulphur compounds, nitrogen compounds, and terpenes were all present, but the differences between the methods were most apparent for lactones. SBSE extracted eight lactones, SAFE extracted four lactones and HSSE and SPME only detected trace levels of two lactones. Six of the lactones—δ-hexa-lactone, δ-octalactone, γ-decalactone, γ-dodecalactone, δ-tetradecalactone, and δ-hexadeca-lactone—were identified for the first time in spray-dried sheep milk. The present work demonstrated that SBSE is an effective tool for the extraction and analysis of volatiles, especially lactones, in sheep milk and dairy products in general. A discussion of the benefits and limitations of each method is included.

Optimization of nuclear magnetic resonance and gas chromatography-mass spectrometry-based fingerprinting methods to characterize goat milk powder

“…The only sulfurcompound identified among the volatile components of fresh milk in the study of (Moio et al, 1993) was dimethyl sulphone. High et al (2019) also noted that the SPME technique enables extraction of this small polar compound, which is consistent with the result of the present study.…”

“…However, in the current study, only 2 ester compounds were identified in the New Zealand GMP using the HS-SPME-GC-MS procedure (Table 2). A similar result was reported in the study of High et al (2019), where esters were not found in the spray-dried New Zealand sheep milk. It was suspected that high thermal load from pasteurization to subsequent spray-drying of the milk powder had affected the levels of esters by decreasing or eliminating them in milk.…”

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

“…All DI-HiSorb techniques (DI-HiSorb S and DI-HiSorb NS), independent of GC column polarity, were characterized by the large volume of lactones extracted (>82%), which differs considerably to all of the other extraction techniques. A similar result was found for SBSE, which is a comparable technique to DI-HiSorb that also used PDMS as the sorbent phase [19]. The only other significant number of chemical classes extracted by DI-HiSorb NS were aldehydes, ketones, and furans, but DI-HiSorb NS did not extract any alcohols, sulphur compounds, acids, terpenes, or esters with the non-polar GC column (but did extract low levels, from 0.5-0.63%, with the polar GC column).…”

An Overview on Truffle Aroma and Main Volatile Compounds

“…However, the extensive sample handling during SAFE, reduce the reproducibility of this extraction technique. Moreover, the lack of sampling automation and the long sample preparation time required, are the main reasons explaining the reduced use of DSE-SAFE in the extraction of aroma compounds in truffles [ 96 ].…”