Aspects of meat and eating quality of broiler chickens reared under standard, maize-fed, free-range or organic systems

1. The effects of rearing chickens using standard, maize-fed, free-range or organic production systems on meat quality and sensory characteristics were evaluated. The standard system used either Ross or Cobb birds with a slaughter age of approximately 40 d, the other systems in the trial used Hubbard birds with considerably older slaughter ages, up to 72 d in the case of organic systems. 2. Paired breast fillets from 120 birds, 30 from each rearing system, were used. The meat quality variables, ultimate pH, colour coordinates L*, a*, b* and water-holding capacity were measured and taste panel assessments were made using 8-point category scales of texture, juiciness, abnormal flavour, flavour liking and overall flavour. 3. There were significant differences between rearing systems, with fillet muscles from birds grown under the standard system having a higher ultimate pH. Differences were also seen in colour with fillets from birds reared under a standard system having a smaller hue angle than those grown using the maize-fed system which had the highest. 4. Fillets from birds reared in the standard system were rated by the taste panel as more tender and juicy. There were no significant differences in chicken flavour. Based on hedonic assessments of flavour liking and overall liking, by a small panel of assessors, meat from birds produced in the standard system was most preferred and that from organic systems the least preferred. Meat from free-range and maize-fed systems was intermediate in preference. This result reveals a trend, but does not infer consumer acceptance.     

Effect of storage on meat quality in uneviscerated turkeys held at 4°C

1. By comparison with birds examined 1 d after slaughter, those held uneviscerated at 4 °C for a further 7 d showed a statistically‐significant difference in flavour (P < 0·01) when examined by a trained taste panel and the difference increased progressively up to 24 d when the experiment ended.

2. Changes in the composition of the microflora in the small intestine and caecum were investigated because of previous evidence that meat flavour development may be influenced by the metabolic activities of intestinal organisms. The only marked effect of storage was a decline in the numbers of lactose‐positive coliform bacteria in the small intestine; there was no clear evidence of any microbial growth in the gut.

3. Although birds examined at day 8 by a sensory panel or by means of a tenderometer were slightly more tender than those tested at day 1, the differences were not statistically significant; nor were there any significant changes in texture during the remainder of the storage period. Possible reasons for the lack of any marked tenderisation are discussed.

     

Effects of double transport and season on sensorial aspects of lamb's meat quality in dry climates

The objective of the current study was to analyse the effects of double transport and season on sensorial aspects of lamb's meat quality in dry climates. A total of 144 lambs were sampled in a 3 × 2 × 2 factorial design, testing three types of double transport along the residence time at a pre-slaughter classification centre or CC (0, 7 and 28 days) and two seasons (summer and winter), with two replicates in each season. Meat from the M. longissimus was analysed in terms of pH and WHC and tasted by a trained sensory panel in terms of lamb odour intensity, tenderness, juiciness, lamb flavour intensity, fat flavour intensity, liver flavour intensity, metallic flavour intensity and overall liking. Meat sensorial quality traits were not significantly affected by double transport. Season had a significant (P < 0.001) effect on all variables analysed, except for lamb flavour intensity and overall liking. Interactions between the fixed effects were not significant, with the exception of tenderness. Season significantly affects several sensorial variables, and they seem to be independent of double transport, with the exception of tenderness.     

Influence of chilling and thawing procedures on the origin of constituents of fluid lost from chicken carcasses

The present study has shown that more fluid, solids and crude protein were lost from thawing carcasses that had been mechanically chilled in iced water before freezing than from similar carcasses that had not been chilled. Even for carcasses that had not been chilled approximately 1 per cent of the carcass weight was lost as fluid and 0–15 per cent as solids during thawing and holding at 1° C. for 10 days. However, losses were negligible during rapid thawing at 30° C. for 4 hr. It appears that water taken up during chilling causes losses of crude protein and other solids, mainly from the skin, during thawing at 30° C. for 4 hr, but holding at 1° C. for 10 days causes losses both from the skin and from extracellular fluid.

Analyses of pectoralis major and gastrocnemius muscles have shown that there are no appreciable losses of solids or nitrogen from skeletal muscles during mechanical chilling and a trained taste panel could not detect any loss of flavour resulting from this procedure. Although gastrocnemius muscles from carcasses that had been mechanically chilled before freezing had slightly lower solids contents after thawing than the corresponding muscles from fresh, unchilled carcasses, there seem to be no important losses from skeletal muscles during thawing.     

Herbs, thyme essential oil and condensed tannin extracts as dietary supplements for broilers, and their effects on performance, digestibility, volatile fatty acids and organoleptic properties

1. Herbs, thyme essential oil (EO) and condensed tannin (CT) extracts were compared for their effects, as dietary supplements, on broiler growth performance, nutrient digestibility and volatile fatty acid (VFA) profiles in the gut. Cooked meat from the birds fed on diets with 4 herbs and an EO extract was compared by a taste panel against those fed on the control treatment, for organoleptic properties in the meat. 2. Female broiler chicks were fed on wheat-soybean meal diets from 0-42 d of age. These chicks were given either the basal diet (control), or the basal diet with one of rosemary, garlic or yarrow herbs, mimosa, cranberry or grapeseed CT's, or thyme EO supplements (8 treatments in total). Body weight (BW) and feed consumption (FC) were measured. 3. The garlic supplement tended to improve growth rate over the first 7 d, while mimosa CT and thyme EO supplements reduced weight gains. The mimosa supplement in diets significantly reduced FC to d 21. Meanwhile, the addition of a cranberry supplement reduced the digestibility of DM, OM and N, compared with the controls. Dietary thyme EO, yarrow, rosemary and garlic supplements modified caecal isovaleric and isobutyric acid proportions (presented as 'Other VFA'; p < 0.05). Dietary herb significantly affected the intensity of meat flavour, and the potential of observing both garlic and abnormal flavours. There were large differences between the consumption of red and white meat samples, while meat temperature affected several flavour attributes. 4. Broiler performance and digestibility for birds given dietary garlic and grapeseed CT supplements were similar to the controls, and these supplements appear suitable for dietary inclusion. Careful choices are necessary when selecting dietary plant extract supplements for broilers, but beneficial effects can be observed.     

Influence of diet on the intestinal microflora and meat flavour of intensively‐reared broiler chickens

1. An attempt has been made to modify the composition of the gut flora of broiler chickens by dietary means in order to determine any concurrent changes in meat flavour.

2. Birds given a diet containing an increasing proportion of whole wheat supplemented with fresh green vegetable matter (special diet) were compared with conventionally‐fed controls. At 12 weeks of age those receiving the special diet had 10 to 100‐fold higher counts of Escherichia colt and faecal streptococci in the duodenum and lower small intestine and showed differences in the intestinal incidence of species and biotypes of lactobacilli.

3. Evaluation of cooked breast‐meat samples by a trained sensory panel showed a significant difference in flavour (P < 0.01) between conventional and special‐diet birds which varied from perceptually very slight to slight. The main terms used in distinguishing special‐diet birds from conventional controls included ‘richer’, ‘meatier’ and ‘sweeter’.

4. Storage of plucked, uneviscerated birds at 4 °C for 8 d maintained the flavour difference between the dietary groups but the effect of storage on flavour was greater in both groups of birds than the influence of diet alone. The likely influence on flavour of autolytic changes occurring in the muscle during storage of the birds is discussed.     

Evaluation of changes in the taste of cooked meat products during curing using an artificial taste sensor

The purpose of this study was to assess an evaluation method using an artificial taste sensor, in comparison with chemical analysis and sensory evaluation of the taste of meat during curing. Samples of Canadian pork were treated with salt, nitrite and phosphate. Curing time ranged from 0 to 168 h. In the sensory evaluation, there were no significant differences in the all characteristic items at 72‐h cured sample compared to the 0‐h sample. Some of the characteristic items for the 168‐h sample (umami, overall taste, richness and overall palatability) showed significant difference (P < 0.05) compared to the 0‐h sample. Taste sensor analysis indicated that the sensor outputs of bitterness and saltiness were significantly correlated with curing time (R = 0.98 and 0.97, respectively), and total free amino acids (R = 0.91 and 0.96, respectively). The sensor output of bitterness was significantly correlated (R = 0.96) with the sum of amino acids corresponding to bitter taste. The increase in the chemical components contributing to bitterness and/or saltiness was indicated as the cause of the characteristic taste. Taste sensor analysis may be applicable as a qualitative method for evaluating taste characteristics generated during the curing of manufactured cooked meat products.     

Growth and sensory characteristics of organically reared broilers differing in strain,sex and age at slaughter

Abstract

The effects of strain, sex and age on live weight, slaughter weight and sensory characteristics of organically reared broilers in orchards are presented. A total of 450 broilers of three different strains (I 657, Light Sussex, New Hampshire) were reared in an organic research orchard. Half of each strain was slaughtered at 91 days and the other half at 120 days. All broilers were weighed and a clinical welfare assessment was made at slaughter. A trained sensory panel evaluated the breast meat in relation to flavour, smell and texture characteristics defined by the panel. At both 91 and 120 days of age the commercial breed I 657 was significantly heavier than the slower growing strains. Males were significantly heavier than the females across strains. Weight ratios between males and females were nearly the same at both slaughter ages in I 657, whereas weight ratios increased significantly at 120 days in Light Sussex and New Hampshire. No overall effect of strain was found on the flavour and smell of the breast meat. However, the age-related changes in tenderness and toughness differed significantly between strains, since the commercial strain tended towards a tougher and less tender consistency with age, whereas the opposite was the case for the slower growing pure breeds. The positive flavour of salt was significantly improved at 120 days across strains with females having a saltier flavour than the males with age. The positive flavour of sweet corn was improved in the meat from the males, whereas the positive smell of sweet corn was significantly improved in both males and females. No negative effects of age were found.

In conclusion, broilers were tastier when slaughtered at 120 days compared with 91 days. The development in meat tenderness was related to strain, and weights at slaughter were related to both strain and sex.     

Comparison of feeding systems: feed cost,palatability and environmental impact among hay‐fattened beef,consistent grass‐only‐fed beef and conventional marbled beef in Wagyu (Japanese Black cattle)

The objective of this article is to compare feed cost, palatability and environmental impacts among feeding systems of high concentrate (HC), high hay (HH) and grass‐only‐fed (Gof) groups. Feed cost was the sum of costs paid for feed intake times the price of feed per kilogram. Palatability was measured by a panel taste test using HH and Gof beef and analyzed for differences. Environmental impacts were calculated based on 1 kg of Japanese beef yield of CO₂ equivalents (eq) and animal end weights at each feeding stage. Results showed that the HH and Gof feeding systems could significantly reduce feed costs by approximately 60% and 78%, respectively, from the HC. In the panel taste test, 50% and 47.50% of panelists indicated that HH beef was ‘extremely delicious’ and ‘acceptable,’ respectively, while 15% indicated that Gof beef was ‘extremely delicious’; 62.50% indicated that Gof beef was ‘acceptable.’ Environmental impacts of each feeding system in terms of CO₂ equivalents (eq) were 9.32, 6.10 and 2.04 tonnes of eq for the HC, HH and Gof, respectively. The HH was an economical system that produced moderate impacts on the environment and had impressive taste.     

Flavour of goat's milk: A review of studies on the sources of its variations

The specific flavour of goat's milk is undesirable for direct consumption but for cheese production its presence can be advantageous.Norwegian trials have shown that unclean handling of the milk reduces the true flavour. The flavour was not influenced by the presence of a buck.The flavour is influenced by the free fatty acid content, especially the C₆ to C₁₀ acids, and also may be affected by the KCl content and the presence of three different cresols. The flavour is negatively correlated to the organic substances in the milk. A strong flavour in the milk causes a strong flavour in the product when making brown whey cheese as well as ordinary white cheese.In the Norwegian goat population there is a positive phenotypic, and maybe also a positive genetic, correlation between yield and strong flavour. The heritability for flavour is estimated to be about 0.25. A significant difference has been found between Norwegian and Saanen goat's milk, both in flavour intensity and free fatty acid content.The flavour was less pronounced at the start and the end of lactation. Small differences were found in the flavour when comparing milk produced by goats fed on pasture and indoors. High feeding intensity by means of concentrates generally increased the flavour of the milk. In general the method of feeding and different feedstuffs have little influence on the true flavour of the goat's milk.     

Effect of sex and carcass weight on sensory quality of goat meat of Cabrito Transmontano

The main purpose of this work was the characterization of Cabrito Transmontana goat kid carcass and meat, which is a Protected Origin Designation product. The effects of sex and carcass weight were studied. Sensory attributes of toughness, juiciness, flavor intensity, flavor quality, odor intensity, fiber presence (stringy), sweet intensity, and overall acceptability were evaluated in 60 males and females allocated to 3 carcass weight groups: 4, 6, and 8 kg. Sensory quality of meat was evaluated by a trained taste panel of 11 experts in 5 sessions. Generalized Procrustes analysis was performed, and 93% of total variability was explained by the 2 first factors (axes). Correlation between sensory traits and factors 1 and 2 allowed the factors to be renamed as toughness/aroma and juiciness/acceptability, respectively. Procrustes analysis indicated that a sex effect was detected by experts. Meat from males presented greater juiciness, flavor quality, and general acceptability than did meat from females. Cabrito Transmontano Protected Origin Designation includes animals from 4 to 9 kg of carcass weight. However, differences among them can be important, because the taste panel found differences between animals from distinct carcass weight ranges. Lighter weight carcasses were considered more tender with less flavor and odor intensity than heavier carcasses.     

Chemical and organoleptic changes in poultry meat resulting from the growth of psychrophylic spoilage bacteria at 1 degree C. 2. Changes in nucleotides

A pigmented strain of Pseudomonas and Pseudomonas putrefaciens grown on minced chicken breast muscle (pectoral proper and supra coracoid) and leg muscle (those covering the femur, fibula and tibia) at 1° C to counts of 10⁸‐10⁹/g produced changes in the nucleotides that were smaller than those due to autolysis and much smaller than the initial differences between the two types of muscle. The likely effects of nucleotide changes on flavour are discussed.     

Analysis of FMO genes and off flavour in pork

Off flavours in pork sometimes produce tastes such as sourness, fishy, metallic or other non‐typical flavours and are often caused by low pH. Loss of function mutations in flavin containing mono‐oxygenase 3 (FMO3) are known to be associated with a fishy off flavour in both chicken eggs and cow's milk and a similar autosomal recessive disorder is present in humans resulting in a fishy odour. FMO3 is a member of a gene family that is clustered on human chromosome 1. Comparative mapping suggested that FMO3 and the remaining FMO genes (ex. FMO1 and FMO5) might map to the orthologous region on pig chromosome 9 (SSC9) where a quantitative trait locus (QTL) for off flavour was previously identified. Primers were designed to amplify FMO1, FMO3 and FMO5 gene fragments and several SNPs were discovered and genotyping tests developed. The genotypes from the Iowa State University Berkshire × Yorkshire resource population were used to linkage map FMO1 and FMO3 to SSC9 and FMO5 to pig chromosome 4 (SSC4). QTL and associations analyses were performed using the map containing FMO1 and FMO3. Results demonstrated that FMO3 and FMO1 mapped less than 1 cM away from the peak for the off flavour QTL previously detected on SSC9 and provide indications of an association between the FMO3 polymorphism and off flavour in pork.     

Crossbreeding experiment with beef and dual-purpose sire breeds on Danish dairy cows IV. Physical,chemical and palatability characteristics of longissimus dorsi and semitendinosus muscles from crossbred young bulls

The results presented are part of a beef × dairy cross breeding experiment in which Simmental, Charolais, Danish Red and White Cattle (DRK), Romagnola, Chianina, Hereford, Blonde d'Aquitaine and Limousin bulls are crossbred with cows of Danish Red Cattle (RDM) and Black Pied Danish Cattle (SDM).Young bulls were slaughtered at 300 kg ($\text{7}\text{1}\text{2}$ months of age on average), 12 months and 15 months of age. Samples of m. longissimus dorsi and m. semitendinosus from 305 animals were examined by a taste panel, by chemical analysis and measurements of colour, by shear force, and by adhesion measurements.Sire breed had a significant influence on chemical composition and colour in both muscles. Taste panel scores and shear force values showed that all sire breeds gave tender meat in the longissimus dorsi. Significant differences in tenderness between sire breeds were found only for the semitendinosus, where Hereford crossbreeds obtained the lowest scores, and Limousin and Blonde d'Aquitaine crossbreeds the highest. Corresponding differences between sire breeds were found for adhesion value, collagen content and solubility of collagen in semitendinosus.Meat quality differences are discussed in relation to early and late maturing breeds.     

Expression levels of taste‐related genes in palate and tongue tip,and involvement of transient receptor potential subfamily M member 5 (TRPM5) in taste sense in chickens

The elucidation of the mechanisms underlying the taste sense of chickens will contribute to improvements in poultry feeding, because the molecular mechanism of chickens’ taste sense defines the feeding behavior of chickens. Here we focused on the gene expressions in two different oral tissues of chickens – the palate, which contains many taste buds, and the tongue tip, which contains few taste buds. Using the quantitative real‐time polymerase chain reaction method, we found that the molecular markers for taste buds of chickens, that is α‐gustducin and vimentin, were expressed significantly highly in the palate compared to the tongue tip. Our analyses also revealed that transient receptor potential subfamily M member 5 (TRPM5), a cation channel involved in taste transduction in mammals, was also highly expressed in the palate compared to the tongue tip. Our findings demonstrated that the expression patterns of these genes were significantly correlated. We showed that the aversion to bitter solution was alleviated by a TRPM5 inhibitor in behavior of chickens. Taken together, our findings enabled us to develop a simple method for screening taste‐related genes in chickens. The use of this method demonstrated that TRPM5 was involved in chickens’ taste transduction, and that a TRPM5 inhibitor can alleviate chickens’ bitter taste perception of feed ingredients.     

复合型香辣牦牛肉酱的制作

本文介绍了一种以牦牛肉为主要原料的新型复合型香辣牦牛肉酱的制作,并对产品的配方、工艺流程、原辅材料预处理及生产过程中的操作要点等方面进行了研究,其结果表明:用该生产的复合型香辣牦牛肉酱不但色泽亮丽、咸辣鲜香,而且营养丰富、滋味独特。     

Dietary levels of chia: influence on hen weight,egg production and sensory quality,for two strains of hens

1. Laying hens, 225 white and 225 brown, were fed for 90 d to compare a control diet with diets containing 70, 140, 210 and 280 g/kg chia (Salvia hispanica L.) seed. 2. Hen weight was not significantly affected by diet; however, manure production was less for the hens fed on chia. 3. Egg weight and production, yolk weight, and yolk percentage were determined at d 0, 30, 43, 58, 72 and 90. 4. A sensory evaluation was conducted on eggs produced during the last week of the trial. 5. No significant differences in egg production were found among treatments for the brown hens. 6. With the 280 g/kg chia diet, the white hens produced fewer and lighter eggs than did the hens fed on the control diet. 7. No significant differences were detected in yolk weight until d 90. 8. On this date the yolks produced by the white hens fed on the 70 g/kg chia diet were significantly lighter in weight, whereas the brown hens produced significantly heavier yolks, compared with the hens fed on the control diet. 9. Yolk weight as a percentage of egg weight was lower for white hens throughout the trial except on d 58 with the 140 g/kg chia diet. Significant differences, however, were detected only with the 70 g/ kg chia diet on d 90 and with the 210 g/kg chia diet on d 58, 72 and 90. 10. No significant differences in taste preference or flavour were found among any of the chia treatments and the control.     

Genetic relationships between sex-specific traits in beef cattle: mature weight, weight adjusted for body condition score, height and body condition score of cows, and carcass traits of their steer relatives

Data from the first four cycles of the Germplasm Evaluation Program at the U.S. Meat Animal Research Center (USMARC) were used to investigate genetic relationships between mature weight (MW, n = 37,710), mature weight adjusted for body condition score (AMW, n = 37,676), mature height (HT, n = 37,123), and BCS (n = 37,676) from 4- to 8-yr old cows (n = 1,800) and carcass traits (n = 4,027) measured on their crossbred paternal half-sib steers. Covariance components among traits were estimated using REML. Carcass traits were adjusted for age at slaughter. Estimates of heritability for hot carcass weight (HCWT); percentage of retail product; percentage of fat; percentage of bone; longissimus muscle area; fat thickness adjusted visually; estimated kidney, pelvic, and heart fat percentage; marbling score; Warner-Bratzler shear force; and taste panel tenderness measured on steers were moderate to high (0.26 to 0.65), suggesting that selection for carcass and meat traits could be effective. Estimates of heritability for taste panel flavor and taste panel juiciness were low and negligible (0.05 and 0.01, respectively). Estimates of heritability from cow data over all ages and seasons were high for MW, AMW, and HT (0.52, 0.57, 0.71; respectively) and relatively low for BCS (0.16). Pairwise analyses for each female mature trait with each carcass trait were done with bivariate animal models. Estimates of genetic correlations between cow mature size and carcass composition or meat quality traits, with the exception of HCWT, were relatively low. Selection for cow mature size (weight and/or height) could be effective and would not be expected to result in much, if any, correlated changes in carcass and meat composition traits. However, genetic correlations of cow traits, with the possible exception of BCS, with HCWT may be too large to ignore. Selection for steers with greater HCWT would lead to larger cows.