Volatile component profiles of conventional and lactose-hydrolyzed UHT milk—a dynamic headspace gas chromatography-mass spectrometry study

Abstract

et al.. Volatile component profiles of conventional and lactose-hydrolyzed UHT milk-a dynamic headspace gas chromatographymass spectrometry study.Abstract Lactose-hydrolyzed milk gains still increasing market share, and understanding the chemical characteristics of lactose-hydrolyzed milk products is important for the dairy industry. The aim of the present study was to identify and compare volatile compounds of commercial lactose-hydrolyzed and conventional ultra-high temperature (UHT) milk. For this purpose, the volatile compounds of lactose-hydrolyzed (<1% lactose), conventional (100% lactose), and filtered (60% lactose) UHT-treated milk were extracted using dynamic headspace sampling and analyzed by gas chromatography-mass spectrometry (GC-MS). A total of 24 volatile compounds were identified including ketones, aldehydes, and sulfides. Overall, principal component analysis (PCA) showed grouping of the different milk types, with loadings indicating a higher concentration of ketones in conventional versus lactose-hydrolyzed UHT milk, but PCA also indicated a marked batch-to-batch variation. Elucidation of individual volatile compounds detected also revealed that the content of ketones in general was higher in conventional UHT milk than in lactose-hydrolyzed milk; however, no significant differences in the volatile compound profiles could be identified between the various milk types as a result of the batch-to-batch variation. The present study

Application of PTR‐TOF‐MS for the quality assessment of lactose‐free milk: Effect of storage time and employment of different lactase preparations

“…The profile was in line with the literature available on the topic 7,27 Mass peaks considered relevant for the trends showed in the PCA (Figure 2) were investigated in more details, and those tentatively identified are summarized in Table 2. In supplementary material (S1) temporal trend of the selected mass peaks reported in Table 2, separated for each replicate of production and lactase preparation tested are reported as well.…”

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

“…A total of 43 VCs were identified in UHT milk, including 4 aldehydes, 5 alcohols, 10 ketones, 9 acids, 9 aromatic hydrocarbons, 3 nitrogenous, 2 sulfur containing compound, and 1 alkane hydrocarbon ( Table 3). The number of VOCs identified in UHT milk samples was greater than those in previous studies [4,8,11,13] where were ranged from 8 to 32. Nitrogenous containing compounds were the most abundant, accounting for 46.44% of total VOCs identified in all the UHT milk samples, followed by ketones (24.50%), acids (16.94%), aromatic hydrocarbons (9.35%), sulfur compounds (7.96%), alkane (5.37%), alcohols (2.94%), and aldehydes (0.99%) in decreasing order (Fig.…”

“…The chemical groups of VOCs identified in UHT milk samples were similar to those previously determined by authors. [4,8,11] As far as we know, 2-mercapto-4-phenylthiazole, 2-amino-5-ethoxycarbonyl benzophenone and 2,6,10,14-tetramethyl pentadecane (pristane) were identified in the volatile profile of UHT milk for the first time. The occurrence of these compounds may be associated to the severity of heat treatment applied to milk and the interaction between packaging material and milk.…”

“…This result was in accordance with previous findings in conventional UHT milk. [8][9][10][11] Ketones 2-pentanone, 2heptanone, 2-nonanone, 2-tridecanone, 2-undecanone, and δ-decalactone were identified in all UHT milk samples. As shown in Table 4, 2-heptanone was the most abundant ketone, ranged from 8 to 33%, which followed by 2-nonanone and 2-undecanone, ranged from 1.77 and 0.26% to 11.14 and 2.41%, respectively.…”

“…[2][3][4] The extent of these changes depends on many factors such as the type of UHT heating, the combination heat and time, the quality of initial raw milk, and the duration and temperature storage. [5][6][7][8] In general, UHT milk is characterized by an increase in the amount of methyl ketones, [9,10] hydrocarbons, [4] aldehydes, [10,11] and sulfides. [12] The content and profiles of VCs identified in UHT milk are related to the fat content of milk, the intensity of heat treatment, the homogenization process (pressure/temperature) and the storage conditions.…”