Aroma compounds of fresh milk from New Zealand cows fed different diets.
25 Sep 2001-Journal of Agricultural and Food Chemistry (American Chemical Society)-Vol. 49, Iss: 10, pp 4825-4832
TL;DR: Differences in milk flavor are primarily caused by concentration differences of a common set of flavor compounds, rather than by the occurrence of compounds uniquely associated with a particular feed.
Abstract: Volatile compounds were extracted from fresh milk produced by New Zealand cows using the newly developed solvent-assisted flavor evaporation (SAFE) technique. The two samples that were used came from cows that had been fed on different diets and represented the considerably different flavors of Northern hemisphere and New Zealand milk. Using gas chromatography−olfactometry (GC−O), 71 aroma compounds were found from the milk extracts, 66 of which were identified. Nearly all of the aroma compounds were common to both extracts, despite the two milk samples having quite different flavors. Only one compound, γ-12:2 lactone, was significantly odor-active for the extract of milk from cows fed a supplement diet, but was not found for the extract of milk from cows fed a pasture diet. Thus, differences in milk flavor are primarily caused by concentration differences of a common set of flavor compounds, rather than by the occurrence of compounds uniquely associated with a particular feed. Keywords: Milk; gas chromat...
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TL;DR: The appearance of terpenes in sheep and goat milk is enhanced by grazing on some novel pasture species, such as Galium verum, Cichorium intybus and Chrisantemum coronarium, which modify milk and cheese sensorial profile, compared to grazing on conventional forages.
247 citations
01 Jan 2006
TL;DR: The triacylglycerols are relatively simple molecules consisting of a glycerol backbone to which are esterified three fatty acid molecules as discussed by the authors, and the resultant milk fat is a complex mixture of triacylsglycerol molecules due to the large variety of constituent fatty acids.
Abstract: The lipid (fat) fraction of milk is composed mainly of triacylglycerols, with minor contributions from diacylglycerols, free (unesterified) fatty acids, phospholipids and sterols. Trace amounts of fat-soluble vitamins, β-carotene and fat-soluble flavouring compounds are also present. These lipids exist in milk in the form of small globules surrounded by a membrane, which maintains the integrity of the globule. Although the vast bulk of the lipids are in the core of the globule, some fat is found in the milk fat globule membrane (MFGM), for example the majority of the phospholipids and small amounts of triacylglycerols and sterols. The triacylglycerols are relatively simple molecules consisting of a glycerol backbone to which are esterified three fatty acid molecules. However, the resultant milk fat is a complex mixture of triacylglycerol molecules due to the large variety of constituent fatty acids. The physical properties of the milk fat, for instance, the wide melting range of −40 °C to 40 °C, are in part a consequence of the composition of the triacylglycerol. This can markedly affect the functional properties of dairy products. For this reason, much research has gone into determining the constituent fatty acids and the way they are arranged on the glycerol backbone, and the rationale of variations in the composition. The minor components are also important in the overall attributes of milk fat, for instance the desirable flavour; hence, it is important to understand not only what is in milk lipids, but how they interact.
220 citations
Cites background from "Aroma compounds of fresh milk from ..."
...The principal factor that can change the concentration of the volatile compounds is the feeding regime of the cow ( Bendall, 2001 )....
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TL;DR: It was concluded that 3-methylindole was the major cause of pastoral flavour in sheepmeat, and that fat oxidation products represented a background flavour that varied quantitatively but not qualitatively with fatty acid profile.
Abstract: Variations in diet, age and castration were employed to generate a range of flavours that were chemically analysed to find the cause of ‘pastoral’ flavour in sheepmeat and its relationship to species flavour. Lambs were raised on pasture (ram or castrate) or on a maize-based or lucerne-based concentrate diet (ram only). They were slaughtered at 132 and 232 days. Fat from animals raised on concentrates had lower proportions of fat-hardening stearic acid and higher proportions of oxidation-prone fat-softening oleic and linoleic acids. Concentrations of species-characterising short branched-chain fatty acids (BCFAs), typified by 4-methyloctanoic acid, were lower for pasture-fed lambs, particularly at 232 days, although between-animal variation was high. Castration did not statistically affect BCFA concentration at this age. Correlations between BCFAs and testes weight were not significant, suggesting that they were not acting as sex pheromones. Concentrations of 3-methylindole (skatole) in perirenal fat were higher for the pasture diet at both slaughter dates. Concentrations of 4-methylphenol in the fat were not affected by diet. However, 3-methylphenol was more abundant in pasture treatments. A sensory panel found that the intensity of ‘sheepmeat’ flavour was higher for pasture-raised animals, but that associations of ‘barnyard’ flavour (which has been linked to pastoral flavour) with diet were more complex. The issue was resolved by fat sniffing. Panel responses to heated subcutaneous fat were recorded as frequency of descriptive terms drawn from a limited lexicon. Volatiles from fats pooled by treatment were resolved on a gas chromatographic column whose effluent was monitored by odourport sniffing. Compounds were identified by parallel chromatographic/mass spectrometric runs. The headspace concentrations of these compounds were then measured for individual animals. These data were related to frequency data by the principal component method. ‘Mutton’ and ‘sheepmeat’ odour notes were clearly linked to indoles (skatole particularly) and, to a lesser extent, methylphenol, setting these notes apart from ‘lamb’, an odour note more associated with lucerne and maize diets through higher concentrations of BCFAs. It was concluded that 3-methylindole was the major cause of pastoral flavour in sheepmeat, and that fat oxidation products represented a background flavour that varied quantitatively but not qualitatively with fatty acid profile.
© 2002 Society of Chemical Industry
166 citations
TL;DR: This review provides an update on the understanding of the chemical reactions (lipid oxidation, Strecker and Maillard reactions, thiamine degradation) and a discussion of the principal aroma compounds derived from those reaction or other sources in cooked meat, mainly focused on ruminant species.
Abstract: This review provides an update on our understanding of the chemical reactions (lipid oxidation, Strecker and Maillard reactions, thiamine degradation) and a discussion of the principal aroma compounds derived from those reaction or other sources in cooked meat, mainly focused on ruminant species. This knowledge is essential in order to understand, control, and improve the quality of food products. More studies are necessary to fully understand the role of each compound in the overall cooked meat flavour and their possible effect in consumer acceptability.
163 citations
Cites background from "Aroma compounds of fresh milk from ..."
...It has been suggested that the low pH in the rumen of cows fed concentrate facilitates the concentration of lactones in milk, although they come from α-linolenic acid [102], which might apply to meat....
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TL;DR: The HS-SPME technique developed in this study is accurate and relatively simple, and can be used for the quantification of thermally derived off-flavor compounds in milk.
160 citations
Cites background from "Aroma compounds of fresh milk from ..."
...Volatile compounds in milk have been extensively studied with many extraction techniques including static headspace, purge and trap, and solvent-assisted flavor evaporation (Contarini et al., 1997; Bendall, 2001; Simon et al., 2001; Toso et al., 2002)....
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References
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TL;DR: In this article, a solvent assisted flavour evaporation (SAFE) method was proposed for the isolation of volatiles from either solvent extracts, aqueous foods, such as milk or beer, or even matrices with a high oil content.
Abstract: A compact and versatile distillation unit was developed for the fast and careful isolation of volatiles from complex food matrices. In connection with a high vacuum pump (5×10–3 Pa), the new technique, designated solvent assisted flavour evaporation (SAFE), allows the isolation of volatiles from either solvent extracts, aqueous foods, such as milk or beer, aqueous food suspensions, such as fruit pulps, or even matrices with a high oil content. Application of SAFE to model solutions of selected aroma compounds resulted in higher yields from both solvent extracts or fatty matrices (50% fat) compared to previously used techniques, such as high vacuum transfer. Direct distillation of aqueous fruit pulps in combination with a stable isotope dilution analysis enabled the fast quantification (60 min including MS analysis) of compounds such as the very polar and unstable 4-hydroxy-2,5-dimethyl-3(2H)-furanone in strawberries (3.2 mg/kg) and tomatoes (340 μg/kg). Furthermore, the direct distillation of aqueous foods, such as beer or orange juice, gave flavourful aqueous distillates free from non-volatile matrix compounds.
814 citations
TL;DR: In this paper, the volatile compounds formed during autoxidation of linoleic acid and methyl linoleate at 22-24 °C were analyzed by high resolution gas chromatography and eluate sniffing.
Abstract: The volatile compounds formed during autoxidation of linoleic acid and methyl linoleate at 22–24 °C were analysed by high resolution gas chromatography and eluate sniffing. The application of this technique to stepwise diluted extracts of the volatile compounds allowed the determination of a new parameter, theD-value, which reveals the most intense flavour compounds of an extract.
520 citations
TL;DR: In this paper, a new headspace-GC-sniffing method is proposed, using a recently developed headspace cell, the vapor phase is collected under conditions that mimic well those of an aroma above a food.
Abstract: A new headspace-GC-sniffing method is proposed. Using a recently developed headspace cell, the vapor phase is collected under conditions that mimic well those of an aroma above a food. Data treatment is based on detection frequency, rather than on perceived intensity or successive dilutions as used in other approaches. Repeatability appears satisfactory, and independent panels are even able to generate similar aromagrams, without training prior to the analysis. Using a minimum of six assessors, this technique seems to be more reliable than classical ones. To compare detection frequencies between two aromagrams, an estimation of the least significant difference is given. A theoretical justification of this approach is suggested, on the basis of determination of detection thresholds. Keywords: Headspace-GC-sniffing; impact odorants; detection frequency
276 citations
TL;DR: Hereford yearling steers were alloted to one of three pasture systems: tall fescue, smooth bromegrass- red clover or orchardgrass-red clover and serially slaughtered at 0, 56, 84 and 112 days, with major differences between volatiles from fat of forage-fed compared to grain-fed steers.
Abstract: Hereford yearling steers (N= 144) were alloted to one of three pasture systems: tall fescue, smooth bromegrass-red clover or orchardgrass-red clover. After the grazing period, steers were finished in drylot and then serially slaughtered at 0, 56, 84 and 112 days. Carcass quality grades and yield grade numbers increased when steers were fed grain up to 112 days. Tenderness of loin steaks increased up to 84 days, after which no improvements were observed. Sensory panel scores for grassy flavor of steaks and ground beef decreased up to 112 days. Fifty-three compounds were identified in the volatiles of melted subcutaneous fat by direct sampling-gas chromatography/mass spectro-metry. The major differences between volatiles from fat of forage-fed compared to grain-fed steers were the higher concentrations of 2,3-octanedione and various diterpenoids present in the samples of the forage-fed animals.
176 citations
TL;DR: In this article, the odour activity values (OAV; ratio of concentration to odour threshold) were calculated from quantitative data determined by means of stable isotope dilution assays and from odour thresholds in oil.
Abstract: Sensory evaluation of five different kinds of butter revealed an Irish sour cream butter (ISC) and a farmer sour cream butter (FSC) with the highest overall odour intensities Nineteen odour-active compounds were detected by aroma extract dilution analysis in a distillate of the ISC butter The highest flavour dilution (FD)-factors were found for δ-decalactone, skatole, [Z]-6-dodeceno-γ-lactone and diacetyl followed by [E]-2-nonenal, [Z,Z]-3,6-nonadienal, [Z]-2-nonenal and 1-octen-3-one Odour activity values (OAV; ratio of concentration to odour threshold) were calculated from quantitative data determined by means of stable isotope dilution assays and from odour thresholds in oil Diacetyl followed by δ-decalactone and butanoic acid showed the highest OAVs in the ISC butter and a cultured butter with creamy, sweet odours In contrast, a sweaty, rancid odour predominated in the FSC butter in which butanoic acid showed the highest OAV The odour of a mixture of diacetyl (034mg/kg), δ-decalactone (49 mg/kg) and butanoic acid (36 mg/kg) in sunflower oil was in very good agreement with the odour of the cultured butter containing the same amounts of these odorants The data suggest that the three odorants should be useful as indicators for the objective assessment of the buttery odour note in milkfat-containing products
175 citations