Marbling Level Research Articles

The marbling of carcases is determined more by the characteristics of the animals themselves than by farming practices

Improved marbling could be of great benefit to the beef industry, responding more effectively to consumer preferences and increasing the market value of the product. To identify the management elements that could determine the degree of marbling of carcases, 128 cows were collected on six different farms, each using different breeding and feeding practices. Multiple statistical tests were carried out to determine whether marbling was more influenced by animal characteristics than by management practices. As expected, within the same farm, the practices used to finish the cows were the same from one animal to the next. We confirm that there was indeed a general level of marbling per farm (highly marbled animals coming from farms ‘used’ to producing highly marbled animals), without being able to determine the weight of genetic choices or feeding and management practices in this determinism. However, we were able to establish that very high marbled carcases came from heavier slaughtered animals and were associated with (1) management that maximised finishing times and time spent on grass (during the animal’s life) and (2) finishing diets rich in maize (grain or silage) and containing flax. The practices and performances associated with low and medium marbling carcases were difficult to separate using the indicators available in this study but were opposite to those of high marbling carcases. This ‘overall level of marbling’ on the farm makes it possible to prioritise the practices that favour or do not favour the development of marbling on the carcase, and allows to formulate advice to breeders to increase the marbling of their carcases. However, there are still grey areas to be covered to effectively achieve a maximum success rate, which will require further work and a more detailed characterisation of the practices and genetic orientations of the animals.

Impact of the leptin receptor gene on pig performance and quality traits

The recessive T allele of the missense polymorphism rs709596309 C > T of the leptin receptor gene is associated with intramuscular fat. However, its overall impact on pork production is still partial. In this work, we investigated the all-round effects of the TT genotype on lean growth efficiency and carcass, meat and fat quality using data from an experiment that compared the performance of 48 TT and 48 C– (24 CT and 24 CC) Duroc barrows. The TT pigs were less efficient for lean growth than the C– pigs. Although heavier, their carcasses had less lean content, were shorter and had lighter loins. Apart from increasing marbling and saturated fatty acid content, changes caused by the TT genotype in meat and fat quality are likely not enough to be perceived by consumers. The effect on visual marbling score exceeded that on intramuscular fat content, which suggests a direct influence of the T allele on the pattern of fat distribution in muscle. With current low-protein diets, the T allele is expected to be cost-effective only in niche markets where a very high level of marbling is critical.

An electronic equipment for marbling meat grade detection based on digital image processing and support vector machine

This work proposes an electronic equipment which determines the marbling grade in beef rib eye according to the American grading scale using digital image processing and machine learning, achieving an 88.89 % coincidence level with grading done by beef specialists. Existing solutions which use image processing usually require calibration methods due to working in non-controlled environments. Furthermore, they only acquire the fat distribution from the longissimus dorsi muscle with an approximate accuracy of 80 %, without referring the distribution to any quality standard. In this work, meat samples are placed in a food grade stainless-steel enclosure with a touch screen and a digital RGB camera. The device acquires an image of the rib eye, which is then analyzed using techniques such as adaptive histogram analysis based on the HSV color model, histogram peaks detection for grayscale thresholding and a linear Support Vector Machine (SVM). The SVM determines the marbling grade based on the American Standard and shows it via a graphical user interface. The classifier was compared with a k-Nearest Neighbors (kNN) and Random Forest (RF) models, to choose the one with the best performance for marbling grade prediction. The SVM and the kNN models obtained a better performance than RF in identifying the marbling level. The estimated American Standard grade was compared to gold standard reference tests performed by specialists from the National Agrarian University in Lima-Peru, where the SVM achieved the aforementioned 88.89 % coincidence level.

Phenotypic relationships between meat quality parameters and residual feed intake in Japanese black Wagyu cattle.

Japanese black Wagyu cattle are renowned for producing some of the world's most highly valued and recognized beef with exceptional marbling. Therefore, the primary focus of genetic selection for Wagyu cattle has historically been on meat quality, particularly achieving high marbling levels. However, even when the price of the final product is high, production costs also remain high, especially considering that most of the feed has to be imported. The objective of this study was to evaluate phenotypic relationships between feed efficiency, specifically residual feed intake (RFI), as the most utilized efficiency index in cattle, and various meat quality parameters in Japanese black cattle in order to determine if a common phenotypic selection for these parameters could be feasible. For this, a total of 39 Wagyu cattle were evaluated for feed efficiency over their entire fattening period (900d), with a focus on RFI as a key indicator. Animals were fed high-starch diets with vitamin A deprivation to achieve the desired marbling. Results revealed positive correlations between feed efficiency and meat quality in Wagyu cattle. Specifically, animals with higher feed efficiency exhibited superior meat quality traits, including firmness, marbling, and overall meat rating. When comparing the 20 most extreme RFI individuals (10 most and 10 least efficient), we observed that efficient RFI animals showed increased marbling levels (+13.2%, P = 0.05) and ranking quality (+12%, P = 0.06) of the meat. In conclusion, this research contributes to understanding the interplay between feed efficiency and meat quality in Japanese black Wagyu cattle. Phenotypic correlations observed suggest the possibility of incorporating RFI criteria into genetic selection programs without compromising the prized meat quality traits of Wagyu beef.

Adding value to beef portion steaks through measuring individual marbling

The current Meat Standards Australia (MSA) and AUS-MEAT grading system assumes that marbling through the M. longissmus thoracis et lumborum (loin) is represented by the score of the grading site. However, studies have indicated marbling varies within the beef loin, but commercially individual portion steaks are not graded for marbling. Cube rolls from a wide phenotypic marbling range (n = 102) were collected and sliced into 15 mm portion steaks, which were imaged with a Marel vision scanner to obtain objective marbling scores. Additionally, three locations (grading site, middle, cranial) across each cube roll were tested for intramuscular fat percentage (IMF%). The effect of steak location demonstrated marked variation across the length of the cube roll for both vision scanner marbling scores and IMF%. This variation in vision scanner marbling scores, expressed in units of MSA marbling score, equated to 316 MSA units. This work suggests an opportunity for individual portion marbling measurements and segregation of individual portion cut steaks based upon their marbling levels.

A Postmortem Case Study-An Analysis of microRNA Patterns in a Korean Native Male Calf (Bos taurus coreanae) That Died of Fat Necrosis.

Korean native cattle are highly valued for their rich marbling and flavor. Nonetheless, endeavors to enhance marbling levels can result in obesity, a prevalent contributor to fat necrosis. Fat necrosis is characterized by the formation of necrotic fat masses in the abdominal cavity, which physically puts pressure on affected organs, causing physical torsion or obstruction, resulting in death and consequent economic loss. Pancreatic injuries or diabetes mellitus were reported as factors of fat necrosis in humans; however, the pathogenesis in animals has not been established. In this study, we identified fat necrosis in a 6-month-old Korean native cow and investigated its potential underlying causes. Serum samples were utilized for a microarray analysis of bovine miRNA. Comparative examination of miRNA expression levels between cattle afflicted with fat necrosis and healthy cattle unveiled notable variances in 24 miRNAs, such as bta-miR-26a, bta-miR-29a, bta-miR-30a-5p and bta-miR-181a. Upon conducting miRNA-mediated KEGG pathway analysis, several pathways including the prolactin signal pathway, insulin resistance, autophagy, the insulin-signaling pathway and the FoxO-signaling pathway were found to be significantly enriched in the calf affected by fat necrosis. As a result, this study potentially indicates a potential connection between fat necrosis and diabetes in Korean native cattle.

Applications of Electronic Nose, Electronic Eye and Electronic Tongue in Quality, Safety and Shelf Life of Meat and Meat Products: A Review.

The quality and shelf life of meat and meat products are key factors that are usually evaluated by complex and laborious protocols and intricate sensory methods. Devices with attractive characteristics (fast reading, portability, and relatively low operational costs) that facilitate the measurement of meat and meat products characteristics are of great value. This review aims to provide an overview of the fundamentals of electronic nose (E-nose), eye (E-eye), and tongue (E-tongue), data preprocessing, chemometrics, the application in the evaluation of quality and shelf life of meat and meat products, and advantages and disadvantages related to these electronic systems. E-nose is the most versatile technology among all three electronic systems and comprises applications to distinguish the application of different preservation methods (chilling vs. frozen, for instance), processing conditions (especially temperature and time), detect adulteration (meat from different species), and the monitoring of shelf life. Emerging applications include the detection of pathogenic microorganisms using E-nose. E-tongue is another relevant technology to determine adulteration, processing conditions, and to monitor shelf life. Finally, E-eye has been providing accurate measuring of color evaluation and grade marbling levels in fresh meat. However, advances are necessary to obtain information that are more related to industrial conditions. Advances to include industrial scenarios (cut sorting in continuous processing, for instance) are of great value.

Evaluation of the impact of bone-in versus boneless cuts on beef palatability

Palatability traits of ribeye, strip loin, andtenderloin steaks were evaluated in a bone-in versus boneless scenario. Eatingquality of these cuts was also evaluated in a high quality (upper 2/3 USDAChoice) and a lower quality (USDA Select) product to evaluate the interactionsof marbling level and bone state. Subprimals were collected from both sides of12 beef carcasses per quality grade and aged for 28-d. Product was fabricatedinto 2.5-cm thick steaks and designated for either trained sensory analysis,consumer sensory analysis, Warner-Bratzler Shear Force (WBSF), or fat andmoisture determination. Results from trainedsensory analysis showed bone-in tenderloins and bone-in ribeyes as moreflavorful (P < 0.05) than boneless cuts from the same muscle. Bonestate had no effect (P > 0.05) on trained sensory initial juiciness,myofibrillar tenderness, and overall tenderness scores, or WBSF for any cut.Furthermore, tenderloin samples were rated higher (P < 0.05) bytrained sensory panelists for myofibrillar and overall tenderness than striploin and ribeye steaks, which were similar (P > 0.05). Bone state hadno impact (P > 0.05) on consumer tenderness and flavor ratings forany of the three cuts. But, bone-in strip loin samples were rated juicier andhigher (P < 0.05) overall than boneless strip loin steaks byconsumers. Tenderloin steaks were juicier, more tender, more flavorful, andrated higher overall (P < 0.05) than ribeyes and boneless strip loinsteaks by consumers. Moreover, there were no differences (P > 0.05)between strip loins and ribeyes for flavor liking by consumers and nodifference (P > 0.05) in overall liking rating between ribeyes andboneless strip loin steaks. Overall, bone status had a minimal impact on beefpalatability traits, providing evidence that eating quality is not greatlyimpacted by bone status for any of the cuts evaluated.

Main regulatory factors of marbling level in beef cattle

The content of intramuscular fat (IMF), that determines marbling levels is considered as one of the vital factors influencing beef sensory quality including tenderness, juiciness, flavour and colour. The IMF formation in cattle commences around six months after conception, and continuously grows throughout the life of the animal. The accumulation of marbling is remarkably affected by genetic, sexual, nutritional and management factors. In this review, the adipogenesis and lipogenesis process regulated by various factors and genes during fetal and growing stages is briefly presented. We also discuss the findings of recent studies on the effects of breed, gene, heritability and gender on the marbling accumulation. Various research reported that feeding during pregnancy, concentrate to roughage ratios and the supplementation or restriction of vitamin A, C, and D are crucial nutritional factors affecting the formation and development of IMF. Castration and early weaning combined with high energy feeding are effective management strategies for improving the accumulation of IMF. Furthermore, age and weight at slaughter are also reviewed because they have significant effects on marbling levels. The combination of several factors could positively affect the improvement of the IMF deposition. Therefore, advanced strategies that simultaneously apply genetic, sexual, nutritional and management factors to achieve desired IMF content without detrimental impacts on feed efficiency in high-marbling beef production are essential.

The role of marbling as an intrinsic characteristic at the point of meat purchase–the Taguchi approach

Meat quality is considered a complex concept depending on many characteristics that could be intrinsic or extrinsic. At the same time, intrinsic and extrinsic quality cues affect consumers’ purchasing decisions. The importance of each quality cue was analysed and discussed in previous literature. Thus, colour and level of marbling of fresh meat were defined as key quality cues at the point of meat purchase. These characteristics are mostly related to pork and beef. The aim of this study was to identify quality characteristics that most closely match the consumer’s preferences and at the same time could be related to quality losses. For that purpose, this paper gives a novel approach of the potential application of Taguchi loss function associated with quality characteristics and related losses for colour and level of marbling. This application can be implemented by providing a quality characteristic’s proper target values and limits, which would make the meat production process more consistent.

Physicochemical and Sensory Assessments in Spain and United States of PGI-Certified Ternera de Navarra vs. Certified Angus Beef.

The physicochemical and sensory differences between the PGI-Certified Ternera de Navarra (CTNA) (Spanish origin) and Certified Angus Beef (CAB) (US origin) were assessed in Spain and the USA. To characterize the carcasses, the ribeye areas (REAs), and marbling levels were assessed in both testing places. Twenty striploins per certified beef program were used as study samples. For sensory analysis, the striploins were vacuum packaged and aged for 7 days at 4 °C and 85% RH in each corresponding laboratory. Thereafter, the samples were half cut and frozen. One of the halves was shipped to the other counterpart-testing place. The fat and moisture percentage content, Warner Bratzler Shear Force (WBSF), and total and soluble collagen were tested for all the samples. The CAB carcasses had smaller REAs (p < 0.0001) and exhibited higher marbling levels (p < 0.0001). The CAB striploins had a higher fat content (p < 0.0001) and required lower WBSF (p < 0.05) than the CTNA samples. Trained panelists rated the CAB samples as juicer (p < 0.001), more tender/less tough (p < 0.0001), and more flavorful (p < 0.0001) than the CTNA counterparts. This study shows that beef from both countries had medium-high tenderness, juiciness, and beef flavor scores and very low off-flavor scores. Relevant differences found between the ratings assigned by the Spanish and the US panelists suggest training differences, or difficulties encountered in using the appropriate terminology for defining each sensory attribute. Furthermore, the lack of product knowledge (i.e., consumption habits) may have been another reason for such differences, despite the blind sensory evaluation.

An image analysis approach to identification and measurement of marbling in the intact pork loin

An image analysis method for identifying marbling on exposed boneless pork loin surfaces was developed, solving the problem of influences from uneven lean colour. Comparing results from RAW and JPEG images of the mid-loin pork chop showed that, except at very high marbling levels, estimation of %IMF (intramuscular fat) was similar with both image types (R2 = 0.72 and 0.74 respectively). Marbling calculated from JPEGs was positively related to %IMF, but also diverged as %IMF increased. Estimations of %IMF at the mid-loin chop from JPEGs of external loin sites showed marbling on the posterior face to be the most strongly related (r = 0.72, P < 0.0001), followed by the ventral surface (r = 0.62–0.64, P < 0.0001), and the anterior face (r = 0.56, P < 0.0001). For on-line application, computing speed is important. This study suggested that an image capture system could be reduced to the capture of a cyan-filtered monochrome JPEG image for analysis.

Fat depot-specific effects of body fat distribution and adipocyte size on intramuscular fat accumulation in Wagyu cattle.

Ectopic fats have been recognized as a new risk factor for metabolic syndrome. In obese humans, ectopic fat accumulations are affected by body fat distribution. Intramuscular adipose tissue is categorized as one of the ectopic fats. Japanese black cattle (Wagyu) are characterized by the ability to accumulate high amounts of intramuscular adipose tissue. In Japan, the marbling level is indicated by the beef marbling standard number (BMS No.), which reflects the intramuscular fat content of longissimus muscle. We hypothesized that the intramuscular fat accumulation is affected by the body fat distribution in Wagyu cattle. In this study, we showed that the BMS No. was not correlated with the subcutaneous and visceral adipocyte diameter. In contrast, the BMS No. was positively correlated with intramuscular adipocyte diameter. These results indicate that the intramuscular adipocyte diameter of Wagyu is hypertrophied with an increase in the intramuscular fat accumulation. In addition, we showed that the BMS No. was positively correlated with the subcutaneous fat percentage. In contrast, the BMS No. was negatively correlated with the visceral fat percentage. These results indicate that highly marbled Wagyu cattle have a higher percentage of subcutaneous fat and a lower percentage of visceral fat.

Comparison of Fatty Acid Content between New Zealand Grass-Fed and American Grain-Fed Beef Strip Loins Varying in Marbling Level

ObjectivesMarbling impacts eating quality and consumer preference of beef as it intensifies flavor, and improves tenderness and juiciness. Triglycerides are the predominate lipid in beef and are considered neutral fatty acids, whereas polar fatty acids are found in the phospholipid portion of beef. Diet of cattle during the finishing period can impact type and saturation of fatty acids in meat.The objective of this research was to evaluate differences in neutral and polar lipid fatty acid content from grass-fed and grain-fed beef of varying quality grades sourced from New Zealand and the United States, respectively.Materials and MethodsBeef strip loins (n = 200) representing two fed cattle types (n = 100/finishing type: grass-finished and grain-finished) and five different USDA quality grades (n = 20 per quality grade: USDA Standard, Select, Low Choice, “Top” Choice: High and Average Choice, and Prime) were acquired from beef processing facilities in New Zealand (grass-fed) and Nebraska (grain-fed). A face steak was cut from the anterior end of each strip loin for fatty acid analysis. Face steaks (n = 200) were frozen and stored at the Gordon W. Davis Meat Science Laboratory until further fabrication. Samples were thawed for 12 to 24 h, trimmed of subcutaneous fat and connective tissue and ground. The ground sample was frozen in liquid nitrogen and homogenized for fatty acid analysis. Lipids were extracted, fractionated into neutral lipid (NL) and polar lipid (PL), derivatized to fatty acid methyl esters and determined by gas chromatography.Statistical analyses were conducted using the procedures of SAS (Version 9.3; SAS Inst. Inc., Cary, NC). Treatment comparisons were tested for significance using PROC GLIMMIX with α = 0.05.ResultsInteractions of cattle diet × marbling level affected the overall concentrations (mg/g) of NL saturated fatty acids (SFA), monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) (P &lt; 0.05). Saturated fatty acid and MUFA NL concentration decreased as marbling level decreased, as grain-fed Prime was higher (P &lt; 0.05) than all other treatments. Grain-finished and grass-finished Standard had the lowest (P &lt; 0.05) SFA and MUFA NL concentration compared to all other treatments. Concentration of PUFA NL was higher (P &lt; 0.05) for grain-finished Prime than grain-finished Top Choice and grass-finished Prime. No difference was found between grain-finished Low Choice and Select and grass-finished Top Choice NL concentration (P &gt; 0.05), however all were higher (P &lt; 0.05) than grass-finished and grain-finished Standard and grass-finished Select. A cattle diet × marbling level interaction affected the overall PL concentrations of SFA and MUFA (P &lt; 0.05), but not PUFA (P &gt; 0.05). Generally, polar fatty acid content increased as marbling increased for SFA and MUFA. Grain-finished PUFA PL concentration was higher (P &lt; 0.05) than grass-finished samples. Additionally, PUFA PL concentration increased as quality grade decreased (P &lt; 0.05).ConclusionIn conclusion, polar and neutral fatty acid content increased with increasing quality grades except for PL polyunsaturated fatty acids. Additionally, grain-finished beef steaks generally contained a higher SFA and MUFA NL concentration than grass-finished beef steaks for all quality grades except Low Choice and Top Choice.

Influence of Cook Method and Degree of Doneness on Beef Flavor Attributes in Round Steaks

ObjectivesIt has been well established that cooking method, marbling level, and cooked internal temperature endpoint affect beef flavor, the most important driver of consumer acceptance. However, beef cuts respond differently to cooking method and cooked internal temperature endpoint based on their inherent chemical characteristics.Materials and MethodsTreatments were: beef cuts (inside round, bottom round, and eye of round); USDA beef quality grade (upper two-thirds Choice and Select); cooking methods (pan grill, stir fry, stew no marinade, stew marinade, and roast); and internal cook temperature endpoints (58, 70, and 80°C). The pan grill cook method included 0.25 and 0.75 in samples from each muscle type. The stir fry cook method treatment was limited to 0.25 in cuts, which were cut into 1.00 in strips prior to cooking. The marinated and non-marinated stew cook method treatments included 0.25 and 0.75 in samples from each muscle. These samples were then cut into 0.25 × 1.00 × 1.00 in and 0.75 × 1.00 × 1.00 in samples prior to cooking. Stew marinated samples were marinated with 118 mL water, 90 mL lemon juice, 30 mL canola oil, 5 mL salt, and 2.5 mL pepper. Two lb roasts were cut from bottom round and eye of round subprimals and inside round subprimals were cut into 2.00 in roasts prior to cooking. An expert descriptive beef flavor and texture attribute panel evaluated each sample using 16-point scales for flavor and texture attributes. Warner-Bratzler shear force (WBSF) were determined. The trained panel results and WBSF values were analyzed using Proc Means and Proc GLMMIX procedures of SAS (version 9.4, SAS Institute, Cary, NC) with a predetermined α of 5%.ResultsQuality grade impacted flavor for the inside round (P &lt; 0.05). USDA quality grade had minimal effect on tenderness as expected, as beef round cuts are highly active muscles in the animal and contain considerable amounts of connective tissue. Cooking method and internal cook temperature endpoint, or cooking time for the stewing cooking treatment, impacted beef flavor to a greater extent (P &lt; 0.05). When pan fried, thicker cuts resulted in more positive flavor attributes. For cuts that were roasted, cooking to higher internal temperatures resulted in higher levels of beef identity, roasted, and umami flavors and less serumy/bloody flavors, as well as decreased tenderness (P &lt; 0.0001), especially in inside round roasts. Marinated round cuts were more tender than their non-marinated counterparts (P &lt; 0.0001). Cuts that were thinner and had longer cooking times were more tender but had more off-flavor attributes (P &lt; 0.05).ConclusionCut thickness, cooking method, length of cooking or internal cook temperature endpoint, and presence of marinade affected flavor and texture of bottom round, eye of round, and inside round cuts. This data will be useful in providing consumer and food service personnel recommendation on how to maximize the flavor and texture of beef round cuts.

Effects of Dry Heat Cooking Method and Quality Grade on the Composition and Objective Tenderness and Juiciness of Beef Strip Loin Steaks

ObjectivesThe objective of this study was to evaluate instrumental measures of tenderness and juiciness of beef strip loin steaks representing four different USDA quality grades cooked using four dry heat cooking methods.Materials and MethodsStrip loins (n = 12/quality grade) were collected from four USDA quality grades [Prime, Top (upper 2/3) Choice, Low (lower 1/3) Choice, and Select]. At 21 d postmortem, strip loins were cut into 2.5 cm thick steaks and stored at –20°C until analysis. The most anterior steak was used for compositional analysis and every three adjacent steaks were grouped and assigned randomly to one of four different dry heat cooking methods [electric clamshell grill (CLAM), flat-top gas grill (FLAT), charbroiler gas grill (CHAR), and salamander gas broiler (SAL)]. Objective measures for raw samples included proximate composition and for cooked samples included cooking loss, pressed juiciness (PJP), and slice shear force (SSF) after the sample was cooked to a medium degree of doneness (70–72°C). In addition, consumers assessed attributes for each sample on an electronic ballot with a 100-point continuous line scale for juiciness, tenderness, flavor liking, and overall liking. Proximate data were analyzed using the GLIMMIX procedure of SAS with quality grade as the fixed effect. All other data were analyzed as split-plot design with quality grade as a whole plot factor, the strip loin as the whole plot unit, and cooking method as a subplot factor.ResultsUSDA Quality grade influenced fat, moisture, and protein percentage (P &lt; 0.01). As expected, there was a fat percentage difference (P &lt; 0.05) between each grade with a decline from Prime to Select samples. Therefore, Select had a greater (P &lt; 0.05) moisture percentage than any other quality grade, and an inverse relationship was observed as there was an increase in moisture between each grade from Select to Prime (P &lt; 0.05). Select and Low Choice had greater (P &lt; 0.05) protein percentage than Top Choice or Prime, which were similar (P &gt; 0.05). As expected, an inverse relationship between increased marbling levels and decreased SSF scores were also observed resulting in a negative correlation between fat and objective tenderness (r = –0.15; P &lt; 0.05). In addition, fat was positively associated with consumer palatability scores (r ≥ 0.21; P &lt; 0.01). Cooking method influenced (P &lt; 0.01) cooking loss, but did not impact SSF or PJP (P ≥ 0.19). CLAM had lower (P &lt; 0.05) cooking loss than FLAT, SAL, and CHAR, which did not differ from each other (P &gt; 0.05). The lower cooking loss of CLAM could be related to the shorter cooking times compared to the other methods. Pressed juiciness percentage was not influenced by quality grade, cooking method, or their interaction (P ≥ 0.19) and was not related to any objective or subjective measures of palatability (P &gt; 0.05). Slice shear force was not influenced by quality grade, cooking method, or their interaction (P ≥ 0.15); however, SSF was related (r ≤ 0.18; P &lt; 0.05) to tenderness, juiciness, flavor and overall liking.ConclusionIn the current study, quality grade influenced the composition of raw samples, yet, quality grade coupled with different dry heat cooking methods did not influence objective measures of tenderness or juiciness.

Evidence of marbling as a single connected entity in beef striploins

Serial sections of Angus striploins that varied in marbling were analysed in three dimensions to assess potential differences in intramuscular fat structure. The majority of the intramuscular fat appeared to be connected along the 100 mm of muscle in both the highly marbled and less marbled striploins. Thus, rather than having dispersed individual flecks of marbling, the intramuscular fat was a single entity within the striploin. The local shape patterns of this entity varied with marbling level in that the structure had an increased diameter in the highly marbled striploins. However, the amount of branching in the intramuscular fat did not vary with the level of marbling. The results suggest that marbling may occur along an internal structure, such as the vascular system or interstitium, in the longissimus muscle. It is postulated that when beef marbling increases, additional intramuscular fat is not deposited in isolated sites but along this internal structure, widening the existing entity rather than changing the shape.

Adipogenesis, fibrogenesis and myogenesis related gene expression in longissimus muscle of high and low marbling beef cattle

Intramuscular fat (IMF) content is critical for the eating quality of beef, but mechanisms regulating IMF deposition remain unsystematically defined. Myogenic and adipogenic cells come from a similar pool of progenitor cells. We hypothesized that adipogenic differentiation was primed in high marbling cattle. To test, two groups of cattle with high and low marbling levels were selected from a uniform group of cattle with the same genetic background and management. By RNA-sequencing, differentially expressed genes were identified. Myogenic genes (eg. MyoG) were up-regulated in the low marbling group, while apolipoprotein E genes (eg. APOE) were down-regulated. Meanwhile, the expression of fibrogenic genes was mixed, with collagen isoforms, COL11A2 and COL22A1 more highly expressed in the high marbling group, and COL14A1, COL16A1, COL1A1 and COL1A2 more lowly expressed. In summary, our data show that adipogenesis was elevated in high marbling cattle accompanied by weakened myogenesis, pointing to the developmental origins of differences in beef marbling.

Effect of visual marbling levels in pork loins on meat quality and Thai consumer acceptance and purchase intent.

ObjectiveWe investigated visual marbling level (VML) influence on pork loin physicochemical traits, consumer palatability responses, VML liking, purchase intent, and their relationships.MethodsFor each of five slaughtering dates, at 24-h postmortem, nine paired Duroc castrated male boneless Longissimus dorsi (LD) muscles were categorized into low (LM, score 1 to 2, n = 3), medium (MM, score 3 to 4, n = 3), and high (HM, score 5 to 6, n = 3) VML. Meat physicochemical quality traits and consumer responses (n = 389) on palatability and VML liking, and purchase intent were evaluated. The experiment was in randomized complete block design. Analysis of variance, Duncan’s multiple mean comparisons, and correlation coefficients were determined.ResultsVML correspond to crude fat (r = 0.91, p<0.01), but both were reversely related to moisture content (r = −0.75 and −0.91, p<0.01, respectively). As VML increased, ash (p<0.05) and protein (p = 0.072) decreased, pH and b* increased (p<0.05), but drip, cooking (p<0.05) and thawing (p = 0.088) losses decreased. Among treatments, muscle fiber diameter, sarcomere length, total and insoluble collagen contents, L*, and a* did not differ (p>0.05). Compared to the others, HM had lower collagen solubility percentage (p<0.05), but similar (p>0.05) Warner-Bratzler shear force (WBSF). No differences (p>0.05) were found in juiciness, overall flavor, oiliness, and overall acceptability, but HM was more tender (p<0.05) than the others. Based on VML, consumers preferred MM to HM (p<0.05), while LM was similar to MM and HM (p>0.05). Corresponding to VML preference (r = 0.45, p<0.01), consumers (83%) would (p<0.01) definitely and probably buy MM, over LM (74%), and HM (68%), respectively.ConclusionIncreasing VML in pork LD altered its chemical composition, slightly increased pH, and improved water holding capacity, thereby improving its tenderness acceptability. Marbling might reduce chewing resistance, as lower collagen solubility in HM did not impact tenderness acceptability and WBSF. While HM was rated as most tender, consumers visually preferred and would purchase MM.

Comparison of Fatty Acid Content between New Zealand Grass-Fed and American Grain-Fed Beef Strip Loins Varying in Marbling Level

ObjectivesMarbling impacts eating quality and consumer preference of beef as it intensifies flavor, and improves tenderness and juiciness. Triglycerides are the predominate lipid in beef and are considered neutral fatty acids, whereas polar fatty acids are found in the phospholipid portion of beef. Diet of cattle during the finishing period can impact type and saturation of fatty acids in meat.The objective of this research was to evaluate differences in neutral and polar lipid fatty acid content from grass-fed and grain-fed beef of varying quality grades sourced from New Zealand and the United States, respectively.Materials and MethodsBeef strip loins (n = 200) representing two fed cattle types (n = 100/finishing type: grass-finished and grain-finished) and five different USDA quality grades (n = 20 per quality grade: USDA Standard, Select, Low Choice, “Top” Choice: High and Average Choice, and Prime) were acquired from beef processing facilities in New Zealand (grass-fed) and Nebraska (grain-fed). A face steak was cut from the anterior end of each strip loin for fatty acid analysis. Face steaks (n = 200) were frozen and stored at the Gordon W. Davis Meat Science Laboratory until further fabrication. Samples were thawed for 12 to 24 h, trimmed of subcutaneous fat and connective tissue and ground. The ground sample was frozen in liquid nitrogen and homogenized for fatty acid analysis. Lipids were extracted, fractionated into neutral lipid (NL) and polar lipid (PL), derivatized to fatty acid methyl esters and determined by gas chromatography.Statistical analyses were conducted using the procedures of SAS (Version 9.3; SAS Inst. Inc., Cary, NC). Treatment comparisons were tested for significance using PROC GLIMMIX with α = 0.05.ResultsInteractions of cattle diet × marbling level affected the overall concentrations (mg/g) of NL saturated fatty acids (SFA), monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) (P < 0.05). Saturated fatty acid and MUFA NL concentration decreased as marbling level decreased, as grain-fed Prime was higher (P < 0.05) than all other treatments. Grain-finished and grass-finished Standard had the lowest (P < 0.05) SFA and MUFA NL concentration compared to all other treatments. Concentration of PUFA NL was higher (P < 0.05) for grain-finished Prime than grain-finished Top Choice and grass-finished Prime. No difference was found between grain-finished Low Choice and Select and grass-finished Top Choice NL concentration (P > 0.05), however all were higher (P < 0.05) than grass-finished and grain-finished Standard and grass-finished Select. A cattle diet × marbling level interaction affected the overall PL concentrations of SFA and MUFA (P < 0.05), but not PUFA (P > 0.05). Generally, polar fatty acid content increased as marbling increased for SFA and MUFA. Grain-finished PUFA PL concentration was higher (P < 0.05) than grass-finished samples. Additionally, PUFA PL concentration increased as quality grade decreased (P < 0.05).ConclusionIn conclusion, polar and neutral fatty acid content increased with increasing quality grades except for PL polyunsaturated fatty acids. Additionally, grain-finished beef steaks generally contained a higher SFA and MUFA NL concentration than grass-finished beef steaks for all quality grades except Low Choice and Top Choice.