Identification of Aroma-active Compounds in Milk by GC×GC-O-TOF-MS Combined with Check-all-that-apply.

Understanding consumers' sensory preferences for dairy products is essential. This study employed sensory analysis and instrumental techniques to analyze the flavor of pasteurized milk and ultra-high temperature (UHT) milk. There were 6 milk samples with similar fat content (4.0-4.6 g/100mL) and protein content (3.2-3.8 g/100mL). Sensory data from consumer tests was collected using CATA (n = 100) and 9-point hedonic preferences. Research showed that Chinese consumers could distinguish the flavor of the 2 types of milk, and UHT milk showed a higher preference score, which may be due to the more pronounced milky flavor and sweet taste of UHT milk. A total of 48 aroma-active compounds were sniffed through GC × GC-O-TOF-MS, among which 11 were determined as key aroma-active compounds. Correlation analysis showed that milky odor, sweetness, and aftertaste-milky were positively correlated with γ-dodecalactone and γ-nonanolactone. Cooked and oxidized taste were positively correlated with 1-octen-3-ol and E-2-octenal. This study is important for developing Chinese dairy products and exporting dairy products to China by multinational companies.

Functional properties and flavor characteristics of milk from cows supplemented with jujube powder.

Jujube has various functional properties and is a promising source of bioactive compounds and flavors. This study investigated the functional properties and flavor characteristics of milk from cows supplemented with jujube powder (JP). Here, milk volatile profiles and taste properties were analyzed by using an electronic nose, and headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS). Compared with the control group, the total antioxidant capacity, 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulphonic free radical scavenging activity, lactoferrin, and IgG levels increased significantly in the JP group. Volatile flavor analysis indicated that ketone levels increased, while acid abundance decreased, and toluene and dimethyl sulfone significantly increased in the JP group. Taste profile analyses demonstrated that jujube supplementation altered the taste of the milk. In summary, dietary jujube powder supplementation affects the volatile flavor composition and aroma of milk, as well as the bioactive component and antioxidant properties. These findings enhance our understanding of milk production using direct dietary supplementation to produce sustainable dairy products.

Lipase-catalyzed modification of the flavor profiles in recombined skim milk products by enriching the volatile components.

The purpose of this study was to modify the amount and composition of volatile components in bovine milk products, in an attempt to create a recombined skim milk product with full-fat milk flavor but with only 0.5% fat. The experimental plan included lipase-catalyzed hydrolysis and esterification reactions using Palatase 20000L (Novozymes, Bagsværd, Denmark). The results, measured by the methods of volatile compositional analysis and sensory evaluation, showed that the flavor profiles of the optimal recombined milk products were effectively modified in this way, possessing intensified characteristic volatile flavor components with rather low level of fat contents, and the sensory characters were quite realistic to natural whole milk flavor.

Milk composition and flavor under different feeding systems: a survey of dairy farms.

Understanding the influence of regional dietary factors on the flavors of milk and dairy products will provide consumers with more options and promote the conservation of regional resources and the original terroir. The objective of this study was to evaluate the influence of regional differences in feeding systems on the composition, fatty acid content, and flavor of pasteurized milk at the farm level. Nine dairy farms using grass silage (GS), 6 farms using maize silage (MS), and 4 farms using by-products (BP) as the characteristic feed components were chosen for this survey. Fresh milk was sampled once per month from September 2008 to February 2009 at each dairy farm. The percentages of GS, MS, and BP (soybean curd residue or brewer's grain) in the feed were 32.4, 22.1, and 15.1%, respectively. The milk fat, protein, and lactose contents did not differ among the milks from farms with different feeding systems. Fatty acids with chain lengths of less than C16 and saturated fatty acids were present at higher concentrations in the milks from the GS and MS farms than in the milk from the BP farms; conversely, fatty acids with chain lengths greater than C18 and unsaturated fatty acids (UFA), including mono- (MUFA) and polyunsaturated fatty acids (PUFA), were present at higher concentrations in the milks from the BP farms than in the milks from the GS farms. No significant differences were detected in milk flavor, evaluated as sweetness, body, texture, aftertaste, and palatability, between the milks from the farms with different feeding systems. The proportion of BP in the cow's diet was positively correlated with the concentrations of fatty acids with chain lengths greater than C18 and with UFA, MUFA, and PUFA. In contrast, the proportion of GS in the diet was positively associated with the levels of milk fat, protein, fatty acids with chain lengths less than C16, and SFA. The MUFA, PUFA, UFA, and fatty acids with chain lengths greater than C18 were not associated with any of the milk flavors. These results suggest the regional differences in feeding systems contribute to the differences in the fatty acid compositions of milk at the farm level. However, these differences do not influence the flavor of pasteurized milk. Thus, more specific feed profiles will be required to provide a specific regional flavor to pasteurized milk.

The Flavor of Dairy Products from Grass-Fed Cows.

The milks used for manufacturing bovine dairy products are not all equal. The feeding regimen of lactating cows can widely vary, giving rise to remarkable compositional differences. Recently, grass-fed/based milk and transformed products are being taken into great consideration due to their more favorable nutritional characteristics and better sustainability over those from intensive systems. Besides these well-established aspects, the existence of differences in flavor is highly debated. The "cheese story tellers" consider it as a proven fact and tend to directly link the aroma of grass-based dairy products to the plants the animals ate. Unfortunately, this claim is not yet supported by scientific data. Actually, there is sufficient evidence of the presence of a distinctive aroma in milk from grass-fed cows, but the connection with specific aroma-active compounds is still in progress. In addition to this, the role of some compounds deriving from cow's metabolism seems to be much more important than that of other compounds that directly derive from feed. The situation in transformed products, in particular cheese, is even more complicated due to the overlapping of flavor compounds originating from technological operations, microbial metabolism and enzyme activities during storage or ripening. Further work is still needed to answer the question, but the increasing application of a flavoromics approach to the studies should rapidly bring about a decisive contribution to the knowledge.

A strategy for the determination of flavor substances in goat milk by liquid chromatography-high resolution mass spectrometry.

A new analytical method for untargeted screening of flavor compounds in goat milk and milk flavor using mass spectrometry was developed and validated. All compounds of low molecular weight were considered as candidate chemicals, instead of focusing only on compounds that already have a known affect on the flavor quality of goat milk. High performance liquid chromatography coupled with high resolution quadrupole orbitrap mass spectrometry based on external standard was used to analyse flavor compounds in complex samples. The untargeted screening strategy is data pre-processing, automated componentization, suspect library spectra searching and the retained analytes confirming based on the reference standard solutions. Forty-two flavor compounds were confirmed and analyzed. The established method was validated by considering the guidelines specified in Commission Decision 2002/657/EC and European SANCO/12571/2013 Guideline 2013. This validated method was successfully applied to samples detection, and some unique flavor compounds were found between goat milk and milk flavor samples, which can provide some useful references for the illicit addition of flavors and fragrances in dairy products.