Diet and growth effects in panel assessment of sheepmeat odour and flavour

The effects of sheep age and diet on several odours and flavours are described. Ram lambs raised on ewe's milk then a corn-based diet were compared with lambs raised on milk and a pasture of grass/clover, six treatments in all. A seventh treatment comprised very old ewes maintained on pasture. Fat and lean from forequarters was minced and cooked together. Cooked lean was assessed for intensity by a sensory panel for 10 flavour attributes. Four showed significant (P < 0.01) treatment effects: 'sheepmeat', 'animal', 'liver', and 'poultry'. Sheepmeat flavour was highest in the slow-grown pasture-fed lambs. Animal flavour-the flavour associated with the odour of confined livestock-showed a similar pattern with treatment. Liver flavour was highest in ewe meat, and the biochemical origin of this flavour is discussed. Eleven related odour attributes were assessed on the rendered fat with a novel olfactometer. Five attributes showed highly significant treatment effects for intensity (P < 0.001): animal and sheepmeat odours showed a similar distribution to the equivalent flavours; likewise cabbage and rancid odours were associated with the two slow-grown pasture treatments. A comparison of the odour and flavour statistics showed that the sense of smell was the more discriminating in sheepmeat assessment, and also confirmed that fat was the true source of sheepmeat odour/flavour. In respect of sheepmeat production for effective marketing, the data showed that at 90 days, a pastoral diet resulted in slightly enhanced odours when compared with a corn-based diet. By 215 days, however, many undesirable odours were exacerbated. Since these older rams were more sexually developed, a sex rather than an age effect could not be excluded. Rendered fat from this work was further used in a companion study (Yang et al., 1997. Meat Sci., 45, 183-200) in an attempt to link individual volatile compounds to odour attributes.     

Fat-borne volatiles and sheepmeat odour

The effects of lamb age and diet on volatiles from fat are described. Rendered fat from ram lambs raised on ewe's milk then a corn-based diet was compared with that from lambs raised on milk and a pasture of grass/clover, six treatments in all. An additional treatment comprised very old ewes maintained on pasture. Helium-borne volatiles of rendered fat were resolved on a DB5 gas chromatographic column and the mass spectra obtained. Long chain alka(e)nes like neophytadiene were dominant in pasture treatments especially where the lamb growth rate was slow. Branch chain fatty acids (4-methyloctanoic, 4-methylnonanoic and an unidentified acid) were also highest in these treatments. Longer chain aldehydes like 2-undecenal were good indicators of a grain diet. Hexanal, commonly associated with rancid odours, was unaffected by treatment. The diketone 2,3-octanedione was an excellent indicator of a pasture diet, as was 3-methylindole (skatole). Phenols showed complex relationships to treatments, but were generally more common in pasture treatments. Benzenethiol (thiophenol) was unaffected by treatment. Inspection of principal component analysis plots identified 10 volatile compounds as contenders for the cause of sheepmeat odour; branch chain fatty acids were confirmed as the leading chemical class. There were indications that puberty or age caused an increase in the odorous 4-methylnonanoic acid. Animal odour-the odour of confined livestock-was clearly causally linked to 3-methylindole, a rumen breakdown product of tryptophan. 3-Methylindole was also responsible for rancid odour, rather than hexanal and its analogues. A hypothesis is advanced that links 2,3-octanedione formation to the enzyme lipoxygenase and linolenic acid, both abundant in green leafy tissue. Overall, the data confirm that sheepmeat odour/flavour is specifically linked to the branch chain fatty acids, and is probably exacerbated by pasture-derived 3-methylindole and alkyl phenols.     

Effect of branched-chain fatty acids, 3-methylindole and 4-methylphenol on consumer sensory scores of grilled lamb meat

Tenderness, flavour, overall liking and odour are important components of sheepmeat eating quality. Consumer assessment of these attributes has been made for carcasses from the Information Nucleus Flock (INF) of the Cooperative Research Centre for Sheep Industry Innovation. The concentrations of three branched chain fatty acids, 4-methyloctanoic (MOA), 4-ethyloctanoic (EOA) and 4-methylnonanoic acids (compounds related to ‘mutton flavour’ in cooked sheepmeat) and 3-methylindole and 4-methylphenol (compounds related to ‘pastoral’ flavour) were determined for 178 fat samples taken from INF carcasses. Statistical modelling revealed that both MOA and EOA impacted on the ‘Like Smell’ consumer sensory score of the cooked meat product (P < 0.05), with increasing concentration causing lower consumer acceptance of the product. None of the compounds though had an effect on the liking of flavour. Obviously, reducing the effect of MOA and EOA on the odour of grilled lamb will improve consumer acceptance of the cooked product but other factors affecting the eating quality also need to be considered.     

The effect of supplementation of a white clover or perennial ryegrass diet with grape seed extract on indole and skatole metabolism and the sensory characteristics of lamb

Condensed tannin in the form of a grape seed extract (GSE) was dosed to weaned wether lambs fed white clover (WC) or perennial ryegrass (PRG) over a 9‐week period to determine whether the ‘pastoral’ flavour and odour of meat could be altered. The concentrations of the pastoral flavour compounds indole and skatole were determined in the rumen fluid, blood plasma and intermuscular fat. The odour and flavour of fat and meat from the slaughtered lambs was assessed by a trained panel. The rumen fluid and blood plasma concentrations of indole and skatole were higher in those lambs fed WC compared to PRG (P < 0.05) and the overall meat flavour intensity was greater when feeding WC (P < 0.01). The observed concentration of indole and skatole in the fat between WC and PRG feeding treatments was not statistically different. Power analysis indicated that increasing the number of lambs per treatment group from 20 to 65 would result in a higher fat skatole concentration (P < 0.05) being detected in lambs fed WC compared to PRG. Dosing with GSE gave a small reduction in skatole concentration in the rumen fluid and reduced plasma concentration of indole and skatole (P < 0.001). Odour and flavour scores of the fat and meat samples were not particularly high however, dosing with GSE lowered the overall and sweet odour and the sheepy, camphor, faecal and barnyard flavour (P < 0.05). Although the plasma concentration of indole and skatole suggests that GSE reduced indole and skatole formation, the intermittent supply of the GSE to the rumen environment was not sufficient to reduce their concentration in the fat. Hence, the small difference in the scores for pastoral odour and flavour attributes associated with GSE treatment may arise from other unknown factors. From a primary investigation, there was no difference in the concentration of indole and skatole in fat samples collected from carcasses before and after chilling. Further investigations into meat pastoral flavour are warranted through feeding condensed tannin‐containing forages. Copyright © 2007 Society of Chemical Industry     

Sensory and chemical changes in five varieties of carrot (Daucus carota L) in response to mechanical stress at harvest and post‐harvest

Carrots harvested by hand or machine and given additional mechanical stress by shaking in a transport simulator were analysed for taste, flavour and content of sugars, terpenes, 6‐methoxymellein and ethanol as well as for ethylene production and respiration. Carrots stressed by shaking had higher ethylene production and respiration, higher content of ethanol and 6‐methoxymellein and lower levels of total terpenes, several individual terpenes and sugars. This corresponded to a higher sensory score for ethanol flavour and odour, bitter taste, earthy flavour, terpene flavour, aftertaste and sickeningly sweet taste and a lower score for acidic taste and sweet taste as measured by an expert taste panel. Ethanol content was highly correlated with ethanol flavour and odour and sickeningly sweet taste. Of five varieties tested, ‘Bolero’ ‘Panter’ and ‘Yukon’ were most sensitive to mechanical stress, whereas ‘Napa’ and ‘Newburg’ were most resistant. Hand‐harvested carrots were not significantly different from machine‐harvested carrots as regards chemical or sensory variables. Principal component analysis showed only slightly different placing of these samples in the score plot. A digital carrot could monitor the degree of mechanical stress to which the carrots were subjected. © 2001 Society of Chemical Industry     

Composition of subcutaneous fat from dry‐cured Iberian hams as influenced by pig feeding

The triacylglycerol and free fatty acid composition and volatile profile of subcutaneous fat of three batches of dry‐cured lberian hams from pigs fed in an extensive system based on acorn and pasture (‘montanera’: MONT) or in confinement with a control diet (FEED) or a 100 mg α‐tocopheryl acetate kg^?1 enriched diet (VITE) were investigated. Triacylglycerol of subcutaneous fat of hams from pigs fed on acorn and pasture (MONT) was more unsaturated, with larger percentages of monounsaturated and polyunsaturated fatty acids, than triacylglycerol of subcutaneous fat of hams from pigs fed on concentrate feeds (FEED and VITE). However, the trend of oxidative processes was quite similar in the groups that contained antioxidants (‘montanera’ and α‐tocopherol supplementation); namely, the highest volatile contents were found in subcutaneous fat of hams from pigs fed on acorn and pasture, while α‐tocopherol supplementation gave rise to a different profile of volatile compounds in comparison with the control diet. Therefore antioxidant presence could contribute to a high intensity and quality of aroma of these hams. © 2001 Society of Chemical Industry     

The effect of different types of pasture on the organoleptic qualities of lambs

The palatability characteristics of carcasses of lambs grazed on either pure perennial ryegrass or Pure lucerne were studied in three experiments. Consumer preferences were ascertained in two experiments with untrained members of the public who scored the meat for flavour, tenderness and juiciness. The type of pasture had no significant effect on the palatability characteristics examined but the shoulder joints were significantly more juicy than the legs. In a third experiment, members of a trained taste punel were able to detect a significantly more intense flavour and odour from the casseroled twelfth rib chop of lucerne-grazed lambs than that from lambs grazed on perennial ryegrass. Since the results from the consumer acceptance tests and the trained taste panel were inconsistent, it is concluded that both methods of assessing palatability should be carried out concurrently in any evaluation of meat quality.     

Sensory characterisation of food and beverage stimuli containing β-ionone and differences between individuals by genotype for rs6591536

The aroma compound β-ionone is present in many fruits and vegetables and their derived products. Odour profiles at different β-ionone concentrations and perceived contributions of β-ionone to food/beverage flavour have only been partially established, and they generally do not extend to differences among individuals who vary in their sensitivity to the odour. Recent research has identified rs6591536, a single nucleotide polymorphism (SNP) located in the coding region of the odorant receptor OR5A1 as responsible for major differences in ability to detect β-ionone odour. In Study 1, using trained sensory panellists (n = 12), odour profiles were obtained for a range of β-ionone concentrations and compared across sensitivity groups defined by genotypes for rs5691536 (GG/AG or AA). A similar comparative approach was used in Studies 2 and 3, where participants (n = 104 and 158) characterised food/beverage stimuli containing added β-ionone using check-all-that-apply questions. The concentration of β-ionone required to elicit perception of the ‘floral’, ‘rose/violet’ and ‘aromatic/fragrant’ characteristics typically associated with β-ionone depended on the background fruit flavour (apple, raspberry, orange) and/or the product type (juice, jelly). It also differed among people classified as more sensitive (“sensitive”) and more insensitive (“insensitive”) to the odour of β-ionone. Perception of negative aspects of β-ionone (incl. ‘sour, acid, vinegar’, ‘sharp, pungent’, ‘soap’, ‘chemical’, ‘artificial’, ‘aftertaste’, ‘woody’) was encountered in all studies, but with varying frequency depending on concentration of added β-ionone and whether participants were “sensitive” or “insensitive” to β-ionone. There was some evidence in Study 3 that perception of β-ionone flavour was masked by the fruity flavours of the test products and that changes in ‘sweet’ and ‘fruity’ were associated with β-ionone spike concentration. Overall, this research suggests a need to consider genotype-encoded sensitivity together with other variables when measuring human flavour perception.     

Effect of duration of the Montanera diet on the hydrocarbon fraction of intramuscular lipids from Iberian dry‐cured ham; characterization by gas chromatography

The characterization and differentiation of Iberian hams was studied as a function of the diet received by animals during the fattening period using a method based on hydrocarbon analysis. Thirty‐one hams were divided into three groups according to fattening diet (1, ‘Concentrate Feed’, fed on an intensive system with concentrates; 2, ‘Short Montanera’, fed on an extensive system with acorns and pasture for 50 days; and 3, ‘Long Montanera’, fed on an extensive system for 75 days). Saturated hydrocarbons in the n‐C₁₄ to n‐C₃₂ range and a large number of branched hydrocarbons were identified in the intramuscular fat of the three groups studied. The diet of the pigs during the fattening period did not affect the n‐alkane and n‐alkene content. The analysis of branched hydrocarbons revealed some significant differences relative to the type of diet. The ‘Concentrate Feed’ group had different concentrations of 2‐butyl‐1,1,3‐trimethylcyclohexane (P < 0.01), 3‐octadecene (P < 0.001), branched hydrocarbon 4 (P < 0.01) and neophytadiene (P < 0.001) than the ‘Montanera’ group. Copyright © 2006 Society of Chemical Industry     

Influence of defined milk products on the flavour of white coffee beverages using static headspace gas chromatography–mass spectrometry/olfactometry and sensory analysis

The influence of milk processing and ingredients on the sensory properties of white coffee beverages has, as yet, not been thoroughly investigated, so in this study analysed milk products processed in a defined manner were added to a standardized, fresh coffee beverage; the resulting odour, taste and retronasal odour perception were measured by intensity tests, and selected volatiles were analysed by static headspace gas chromatography/mass spectrometry. After adding pasteurized consumers’ milk, the effects of a different fat content (3.5 and 1.5%) and fat dispersion were studied. The milk with the lower fat content and with smaller fat globules, resulting from double homogenization (each 250/50 bar), induced a more intense coffee-related retronasal odour perception, whereas the milk-related impression was nearly the same. The addition of casein increased the creamy and milky retronasal odour perception and reduced the coffee-related taste and retronasal odour. These correlations may result in a custom-made development of milky coffee beverages controlled in their nasal and retronasal odour and taste by the defined processing of the milk component. With instrumental analysis it was observable that the effect of the addition of twice-homogenized, twice-pasteurized low-fat milk and of the addition of whole milk was similar. In both cases more volatiles were released from the beverage than with the addition of low-fat milk that was homogenized once. This is an unexpected result, because the whole milk has a higher fat content than the low-fat milk and therefore a greater retention of the flavour compounds was expected. Is it possible that the flavour compounds are not dissolved in fat and that interactions happen only with fat globule membrane constituents?     

Effects of goat milk or milk replacer diet on meat quality and fat composition of suckling goat kids

The effects of a diet with goat milk "GM" or milk replacer "MR" on the meat quality and fat composition of suckling Murciano-Granadina kids were studied. MR consisted of powdered skimmed milk, coconut oil and fat, and cereal products and by-products. Raw meat quality (moisture, protein, lipids, ash, collagen, cholesterol, haem pigments, CIELab colour, pH and water retention capacity), fatty acid "FA" composition and eating quality of cooked meat (odour, flavour and texture) were determined. Diet had only a slight effect on raw meat quality but had a pronounced effect on fatty acid composition and eating quality of cooked meat. MR diet increased the water/protein proportion in the muscle. The saturated/unsaturated FA ratio in GM and MR fat was 0.94 and 2.27, respectively. The major FA in GM and MR fat were C16:0 and C18:1, respectively. Short-chain C4-C12 hardly accumulated in the adipose tissue of suckling kid, increasing the relative percentages of C14-C20. This effect was more pronounced in MR fat, due to the fact that MR contained more short-chain fatty acids than GM. MR diet gave cooked meat a more intense characteristic goat meat odour and flavour, more tenderness and more juiciness than the natural suckling diet. This fact could be related to differences in meat and fat composition.     

Effects of previous diet and duration of soybean oil supplementation on light lambs carcass composition, meat quality and fatty acid composition

Forty Merino Branco ram lambs were used to study the effects of initial diet and duration of supplementation with a conjugated linoleic acid (CLA) promoting diet, on carcass composition, meat quality and fatty acid composition of intramuscular fat. The experimental period was 6 weeks. The experimental design involved 2 initial diets (commercial concentrate (C); dehydrated lucerne (L)), and 2 finishing periods (2 and 4 weeks) on dehydrated lucerne plus 10% soybean oil (O). Data were analysed as a 2 × 2 factorial arrangement with initial diet and time on finishing (CLA promoting) diet as the main factors. The lambs were randomly assigned to four groups: CCO; COO; LLO; LOO according to the lamb’s diet fed in each period.Lambs initially fed with concentrate showed higher hot carcass weights (11.2 vs 9.6 kg) than lambs fed initially with lucerne. The increase of the duration of finishing period reduced the carcass muscle percentage (57.4% vs 55.5%) and increased the subcutaneous fat percentage (5.67% vs 7.03%). Meat colour was affected by initial diet. Lambs initially fed with concentrate showed a lower proportion of CLA (18:2cis-9, trans-11 isomer) (0.98% vs 1.38% of total fatty acids) and most of n−3 polyunsaturated fatty acids than lambs initially fed with lucerne. Initial diet did not compromise the response to the CLA-promoting diet and the proportion of 18:2cis-9, trans-11 in intramuscular fat increased with the duration of time on the CLA-promoting diet (1.02% vs 1.34% of total fatty acids).     

Effect of Brussels sprouts and inulin/rape seed cake on the sensory profile of pork M. longissimus dorsi

The objective of the present study was to evaluate the influence of two diets containing either Brussels sprouts or inulin/rape seed cake, compared with a standard diet (control) for slaughter pigs on flavour and odour attributes and sensory profile of cooked pork. Three weeks prior to slaughter 24 female pigs were allocated to three diets: (1) a standard grower-finishing diet (control) for slaughter pigs containing barley, wheat and soy-bean meal, (2) the control diet containing 11 energy percent Brussels sprouts and (3) a diet containing 25% inulin and 55% rape seed cake. The odour and flavour of the cooked meat from inulin/rape seed cake-fed pigs differed significantly from the other two diets, showing reduced meat odour, increased pig and acrid odour, increased pig flavour, reduced fresh flavour and total impression. Meat from the Brussels sprouts-fed pigs deviated only slightly from the control-fed pigs.     

The effects of castration on the eating quality of dry-cured ham

The influence of the castration of entire male pigs on the eating quality of dry-cured ham was evaluated. Forty-eight dry-cured hams (435-day aged) were studied from entire and castrated males of two different crossbreeds. The proximate composition of the meat and the androstenone, indole and skatole fat content were determined. The entire hams were classified according to the androstenone and skatole content. Sensory analysis was carried out by a trained panel, evaluating marbling, juiciness, saltiness, graininess, toughness, overall flavour, boar odour and boar flavour. Also carried out was a preference and acceptability paired test by consumers. Castration increased meat fattening and reduced the androstenone and skatole levels of the fat. Significant differences (P<0.05) were found between entires and castrates for the average values given in all the sensory attributes studied. The dry-cured ham from castrates was scored as more flavoured, more marbled and softer. It was also perceived as less grainy, less salty and having less boar odour and flavour. The sensory perception of boar odour was more intense than that of flavour in dry-cured ham and appears to be related to the level of androstenone and skatole in fat. Dry-cured ham from castrated males was also more accepted and more preferred by consumers, especially women and habitual consumers. Castration of male pigs contributes to improve the quality of dry-cured ham. The rejection caused by boar odour and flavour is reduced, improving the overall flavour, texture and juiciness. In addition, the saltiness is less pronounced in ham from castrates. For this reason, the production of high quality dry-cured ham will have to shoulder the extra costs associated with processing castrated pigs.     

Effects of variety and stage of fruit ripeness on the physicochemical and sensory characteristics of deep‐fat‐fried banana chips

The quality of banana chips prepared from two different varieties of banana, Pisang Abu and Pisang Nangka, at the ‘green’ and ‘trace of yellow’ stages of ripeness was studied. The fruits were peeled, sliced to a thickness of 2 mm and deep‐fat fried in refined, bleached and deodorised (RBD) palm olein at 180 ± 5 °C for 3 min. The quality parameters determined for fresh bananas were total soluble solids, pH, acidity, carbohydrate, sugar content, fat, protein, moisture content, ash, fibre, colour and fruit firmness. The results showed that Abu had a higher carbohydrate content than Nangka at both stages of ripeness before frying. No sucrose was detected in Nangka. The quality parameters determined after deep‐fat frying were moisture content, water activity, oil absorption, crispness and sensory evaluation. The moisture content and water activity of Abu chips were lower than those of Nangka chips. The texture of chips prepared from Abu at stage ‘green’ showed more crispness than the other three samples. Sensory evaluation showed that chips prepared from Abu at both stages of ripeness presented better colour, flavour, odour, texture and overall acceptability than those prepared from Nangka. Based on the matrix of correlation coefficients, fresh bananas with higher fruit firmness and carbohydrate content gave banana chips with higher crispness and oil absorption. © 2001 Society of Chemical Industry     

Evaluating the use of plant hormones and biostimulators in forage pastures to enhance shoot dry biomass production by perennial ryegrass (Lolium perenne L.)

Fertilisation of established perennial ryegrass forage pastures with nitrogen (N)‐based fertilisers is currently the most common practice used on farms to increase pasture forage biomass yield. However, over‐fertilisation can lead to undesired environmental impacts, including nitrate leaching into waterways and increased gaseous emissions of ammonia and nitrous oxide to the atmosphere. Additionally, there is growing interest from pastoral farmers to adopt methods for increasing pasture dry matter yield which use ‘natural’, environmentally safe plant growth stimulators, together with N‐based fertilisers. Such plant growth stimulators include plant hormones and plant growth promotive microorganisms such as bacteria and fungi (‘biostimulators’, which may produce plant growth‐inducing hormones), as well as extracts of seaweed (marine algae). This review presents examples and discusses current uses of plant hormones and biostimulators, applied alone or together with N‐based fertilisers, to enhance shoot dry matter yield of forage pasture species, with an emphasis on perennial ryegrass. © 2015 Society of Chemical Industry     

LAGER-TYPE BEER MADE FROM EXTRUDED MALT; SENSORY AND CHEMICAL ANALYSES

A lager-type beer was brewed from a mixture of partially dried green malt and extruded green malt (9:1). Small flavour differences were observed in the beer made from the extruded malt when compared with two other types of beer, namely standard lager and beer made from 100% green malt which was partially dried. More than 90 flavour components were described upon sniffing of the GC eluate. Most of them were present in trace amounts which did not allow their identity to be established. However, in all beer samples several unidentified components were described as giving a “roasted”, “burnt”, “bread crust” or “biscuit” odour. These odour characteristics probably derive from the alkylpyrazines present. Positively identified pyrazines were only found in the “extruded” beer, namely methylpyrazine and 2,5 (and/or-2,6)-dimethylpyrazine. However, when the beer was tasted, no characteristics associated with a roasted or burnt flavour were registered. Among the identified flavour components esters and alcohols were abundantly represented.     

Comparison between an odour profile and a flavour profile of dry fermented sausages

Summary  Two preparations of dry fermented sausage inoculated with one of four different strains of Staphylococcus were prepared a week apart and tested twice by 10 trained assessors. Profiles of eight attributes (vinegar, dry sausage, fat, dry cured-ham, pâté, milk, butter and nutty) were monadically assessed twice and scored on non-structured scales. During the first two sessions subjects tasted twice the four dry sausages from both preparations, and during the last two sessions 7 days later they assessed the odour of the same samples in duplicate by sparging with air. Principal component analysis showed that the eight samples (four strains X two preparations) of dry sausage were described similarly by tasting and sniffing except for the fat attribute. The principal component analysis showed that the eight samples of dry sausage were better discriminated by smell than by taste. The smelling procedure resulted in a better recognition of dry sausages inoculated with the same strain of Staphylococcus than that by tasting. Variance analysis showed that product effect was significant on common odour and flavour attributes: 'vinegar', 'fat' and 'butter'; and it was never significant on 'nutty' and 'pâté'. The F-values for 'vinegar', 'fat', 'dry-ham', 'milk' and 'butter' were higher by smell than by taste. Only 'dry-sausage' was better distinguished by taste.