Fresh beef tumbling at different post-mortem times to improve tenderness and proteolytic features of M. longissimus lumborum

The aim of this study was to determine the effects of tumbling at different post-mortem times on the proteolytic features and quality attributes of beef loins (M. longissimus lumborum). Loins (n = 12) were cut into 4 sections and assigned to tumbling at 1, 6 or 11 days post-mortem or non-tumbled control. Upon tumbling, additional ageing was applied to a common post-mortem time of 16 days. In general, tumbling had no considerable impacts on water-holding ability of samples. Tumbling resulted in an immediate decrease in shear force values (WBSF) of beef samples. Tumbling at 1 day post-mortem with no ageing had similar WBSF compared to the non-tumbled controls at 16 days (P > 0.05). With ageing, tumbling increased amounts of protein degradation, myofibrillar fragmentation and calpain-1 autolysis of samples. These results suggest that early post-mortem tumbling coupled with ageing can synergistically impact the tenderness development of beef loins and shorten the necessary ageing period.     

The assessment of commercial beef and chicken bouillons in terms of heterocyclic aromatic amines and some of their precursors

Herein, the assessment of commercial beef and chicken bouillons in terms of heterocyclic aromatic amines (HAAs) and some of their precursors was evaluated. Creatine and creatinine levels were ranged between 0.57–0.80 and 0.28–0.94 mg g⁻¹, respectively. Glutamic acid was found to be the most abundant amino acid in both bouillons. 2-amino-3,7,8-trimethylimidazo[4,5-ƒ]quinoxaline (7,8-DiMeIQx, up to 0.03 ng g⁻¹) was the only quantified analyte in beef bouillons, whereas it (up to 0.08 ng g⁻¹) was determined in addition to 2-amino-3-methylimidazo[4,5-ƒ]quinoxaline (IQx, up to 0.08 ng g⁻¹) in chicken bouillons. Creatine, creatinine and free amino acid composition did not have the capacity to initiate the formation of HAAs. Therefore, bouillons do not pose risk in terms of HAAs. However, it should be noted that multiple factors, such as the substrate amount and production conditions, may affect the results. Glutamic acid content is remarkable in commercial bouillons sold in Turkey.     

Linear correlation between pH value of stimulated beef and electrical current intensity

The aim of the present study was to determine mathematical relationships between pH changes in beef 24 h post-slaughter and changes in the intensity of electrical current flowing through bull and heifer carcasses during high-voltage electrical stimulation. The electrical stimulation was applied 40 min postmortem for 120 s. The pH values of m. longissimus thoracis et lumborum were analyzed in the function of electrical current intensity changes and its change during electrical stimulation. Mathematical linear correlations of the y = ax ± b type were demonstrated between pH values at 2, 6, and 24 h postmortem and the initial (I_i) and ultimate (I_u) electrical current intensity values, the difference between them and the initial pH values determined before electrical stimulation. High multiple correlation coefficients (R² = 0.416, α ≤ 0.001) between I_u and pH values 24 h post-slaughter enabled concluding that there is a possibility to predict a pH value of stimulated carcass with high accuracy, and thus also beef quality, based merely on the ultimate electrical current intensity values.     

Physicochemical and technological properties of beef burger as influenced by the addition of pea fibre

This study aimed to evaluate the physicochemical characteristics and sensory attributes of beef burgers with the addition of pea fibre as a partial substitute of meat or fat. Three formulations were prepared: control (CON) – similar to the commercial formulation; fibre/less meat (FLM)—5% meat reduction and addition of 1% pea fibre; fibre/less fat (FLF)—7% fat reduction and addition of 1% pea fibre. Non-significant differences were obtained for pH, colour parameters (L* and b*), texture profile, cooking loss and size reduction among formulations. Moreover, sensory analysis with consumers of beef burgers did not indicate differences among the formulations for all the analysed attributes. Therefore, pea fibre is a promising partial replacer for meat and fat in beef burgers due to the preservation of technological parameters and sensory acceptance.     

Effects of incorporating roasted lupin (Lupinus angustifolius) flour on the physicochemical and sensory attributes of beef sausage

The effects of incorporating lupin flour on the physicochemical and sensory characteristics of beef sausages were explored. Lupin (Lupinus angustifolius) flour was roasted, then hydrated to match the moisture content of beef meat. The beef sausage samples were manufactured for six treatments by replacing beef with hydrated lupin flour from 0% to 36% (w/w). Proximate analysis revealed that carbohydrate (dietary fibre) level was increased from 9.62% to 19.31%, whereas fat content was decreased from 11.62% to 7.91%. Inclusion of lupin flour increased the meat emulsion stability (fluid released decreased from 9.35% to 1.53%) and decreased cooking loss from 22.70% to 14.30%. Softer texture and greater adhesiveness were observed in lupin-incorporated formulations. Sensory evaluation indicated no significant difference between control and 12% lupin-enriched beef sausage formulation in appearance, aroma, flavour and overall liking, suggesting lupin flour can be added to beef sausage at this level without compromising consumer acceptance.     

Individual trans 18:1 Isomers are Metabolised Differently and Have Distinct Effects on Lipogenesis in 3T3‐L1 Adipocytes

The objective of this research was to study the metabolism of individual trans fatty acids (FAs) that can be found in ruminant fat or partially hydrogenated vegetable oils (PHVO) and determine their effects on FA composition and lipogenic gene expression in adipocytes. Differentiated 3T3‐L1 adipocytes were treated with 200 µM of either trans‐9‐18:1, trans‐11‐18:1, trans‐13‐18:1, cis‐9‐18:1 or BSA vehicle control for 120 h. Trans‐9‐18:1 increased total cell FA content (µmole/well) compared to other FA treatments, which was mainly related to the accumulation of trans‐9‐18:1 in the cells. Adipocytes were able to desaturate a significant proportion of absorbed trans‐11‐18:1 and trans‐13‐18:1 (~20 and 30 % respectively) to cis‐9,trans‐11‐18:2 and cis‐9,trans‐13‐18:2, whereas trans‐9‐18:1 was mostly incorporated intact resulting in a greater lipophilic index (i.e. decreased mean FA fluidity) of adipocytes. Trans‐9‐18:1 up‐regulated (P < 0.05) the expression of lipogenic genes including acetyl‐CoA carboxylase (1.65 fold), FA synthase (1.45 fold), FA elongase‐5 (1.52 fold) and stearoyl‐CoA desaturase‐1 (1.49 fold), compared to the control, whereas trans‐11‐18:1 and trans‐13‐18:1 did not affect the expression of these genes compared to control. Our results suggest that the metabolism and lipogenic properties of trans‐11‐18:1 and trans‐13‐18:1, typically the most abundant trans FA in beef from cattle fed forage‐based diets, are similar and are different from those of trans‐9‐18:1, the predominant trans FA in PHVO.     

Three-Dimensional Measurement of Ice Crystals in Frozen Materials by Near-Infrared Imaging Spectroscopy

A novel technique was developed to recognize ice crystals in biological materials and to analyze their three-dimensional morphology using a Cryogenic Micro-Slicer Spectral Imaging System with a micro-slicer unit and a near-infrared spectral imaging unit. Consecutive cross-sections of a frozen sample were exposed by the multi-slicing operations with a minimum thickness of 1 µm, and their images were taken by the imaging unit. Spectroscopic analysis using a near-infrared spectrum meter showed an absorption peak at 1460 nm for pure water. Based on the observations of the absorption band of ice crystals in the wavelength range of 1450–1570 nm and its peak at 1495 nm, a commodity-type bandpass filter with a central wavelength of 1500 nm was adopted to identify ice crystals in near-infrared images. The absorption peak of water exhibited a tendency to move toward longer wavelengths with decreasing sample temperature from 25 °C to ?15 °C. The filtered images of ice crystals in frozen samples were darker than the other components at the peak wavelength of ice crystals. The three-dimensional reconstructed morphology of ice crystals revealed that they were formed along the direction of heat transfer while freezing. The proposed method provides a novel tool to investigate the effects of freezing conditions on the size, morphology and distribution of ice crystals.     

Steam-assisted roasting inhibits formation of heterocyclic aromatic amines and alters volatile flavour profile of beef steak

In order to evaluate the effect of steam addition during meat roasting, beef sirloin steaks were cooked at five humidities (0%, 25%, 50%, 75% and 100%) under 230 °C to a centre temperature of 71 °C. With increased humidity, heating rate generally increased and the cooked steak gradually lost the typical roasted appearance. Thiobarbituric acid-reactive substances (TBARS) values generally increased, while carbonyl groups were not affected. Increased humidity promoted the formation of volatile aldehydes and alcohols, while pyrazines decreased significantly from 0% to 25% humidity. Steam-assisted roasting inhibited the formation of heterocyclic aromatic amines (HAAs; except for IQ and Norharman). However, further increase in humidity (larger than 25%) did not have additional inhibition effect. Based on the results, it is recommended to roast beef with steam addition to reduce toxic HAAs, but the humidity should be kept at a relatively low level to maintain a typical roasted appearance and flavour profile.     

Influence of ultimate pH on biochemistry and quality of Longissimus lumborum steaks from Nellore bulls during ageing

Ultimate pH (pH_u) is an indicator that influences post-mortem meat quality. We studied physiological and biochemical changes of steaks obtained from Nellore bulls (Bos indicus) during post-mortem ageing. To this, Longissimus lumborum (LL) muscles were classified into three groups: Normal-pH_u (≤5.79), Intermediate-pH_u (5.80–6.29) and High-pH_u (≥6.30) groups, portioned into steaks, vacuum packaged and matured at 2 °C for 0, 7, 14, 21 and 28 days. High-pH_u steaks exhibited impaired colour stability and were darker compared to the other groups. High- and Normal-pH_u steaks showed improved tenderness and myofibrillar fragmentation linked to proteolysis. Intermediate-pH_u steaks were associated with a lower meat tenderness and decreased collagen solubility. High-pH_u steaks retained a high pH during ageing and increased water-holding capacity. These findings provide evidence that highlight pH_u as a strategy for the classification of pH_u-dependent beef quality from Nellore bulls that can be adopted by the Brazilian meat industry.     

Development of a controlling method for Escherichia coli O157:H7 and Salmonella spp. in fresh market beef by using polylysine and modified atmosphere packaging

Escherichia coli O157:H7 and Salmonella spp. often contaminate fresh beef. In Japan, an E coli outbreak caused by raw beef made 181 people ill and 5 individuals dead in 2011. Responding to this outbreak, an effective sterilization method for fresh beef is expected to be developed. In this study, ε-polylysine combined with CO₂-packaging method was examined for controlling these pathogens in fresh beef. At an incubation temperature of 4 °C, approximately 4.3 log and 2.4 log reduction in bacterial numbers were observed after 7-day incubation for E. coli O157:H7 and Salmonella, respectively, in ε-polylysine-added beef. When effectiveness of CO₂-packaging combined with ε-polylysine was investigated, CO₂ did not have additional inhibiting effect on bacterial growth compared to only-ε-polylysine-treated samples when incubated at 4 °C. However, effectiveness of CO₂ was observed when incubated at 10 °C where approximately 2.9 log and 4.4 log reduction in E. coli cell numbers were observed in only-ε-polylysine-treated samples and polylysine- and CO₂-treated group, respectively, and approximately 1.7 log and 3.5 log reduction in Salmonella cell numbers were observed in only-ε-polylysine-treated samples and polylysine and CO₂-treated group, respectively. This study confirmed that ε-polylysine or ε-polylysine combined with CO₂ packaging are effective in preventing foodborne diseases caused by raw beef.