Development of a novel bioactive packaging based on the incorporation of Lactobacillus sakei into sodium-caseinate films for controlling Listeria monocytogenes in foods

A novel packaging technology was developed based on the incorporation of Lactobacillus sakei cells into sodium-caseinate (SC) edible films. Incorporation was based either on direct addition of the cells in the film forming solution used for casting or by surface spraying of the culture on the preformed film, resulting in a population density of 10⁶ cfu/cm². Addition of sorbitol in the film matrix increased the viability of the cells, greater than 90%, upon storage under both refrigeration and ambient temperature conditions for 30 days. Incorporation of the viable protective culture did not affect the mechanical properties and the physico-chemical properties of the film. Application of the films to both laboratory medium (agar) and a food model system (fresh beef) inoculated with Listeria monocytogenes resulted in a rapid growth of L. sakei immobilized in the film following contact with the wet medium or the food surface and a significant inhibition of the pathogen growth compared to the control samples under both constant and dynamic storage temperature protocols. The present study indicated that biopolymer-based antimicrobial films containing cells of a protective culture can be used as an effective packaging technology for improving food safety.     

Determination of meaty peptide in enzymatic hydrolyzate of beef protein by HPLC-MS

The purpose of this study is to detect beefy meaty peptide (BMP) in beef hydrolyzate. The synthesized BMP is used as a standard sample in the study. High performance liquid chromatography (HPLC)/ion trap electrospray ionization mass spectrometry (ESI-MS) with UV detection was applied in qualitative analysis of the peptides. Six beef protein enzymatic hydrolyzate samples were separated on a Surveyor HPLC system through a SUPELCO Discovery® C₁₈ analytical column (5 μm, 15 cm×2.1 mm i.d.). The column was eluted at a flow rate of 0.2 mL/min in a linear gradient elution mode of acetronitrile-water solution with 0.1% trifluoroacetic acid. The concentration of acetronitrile was increased from 5% to 50% in 40 minutes. A Finnigan LCQ Advantage MAX instrument was used as detector to analyze with ESI-MS and ESI-MS/MS in positive mode. Among the six samples of beef protein enzymatic hydrolysate, the BMP is detected and confirmed in sample No.4 with a higher intensity of characteristic peak and is further investigated by ESI-MS/MS. As a result, BMP exists in sample No.4. The study proves that HPLC-ESI-MS/MS is a simple, rapid, sensitive method to analyze target peptides from complex polypeptides.     

Interrelationships between meat quality traits, texture measurements and physicochemical characteristics of M. rectus abdominis from Charolais heifers

Ninety-nine Charolais heifers were used to study the variability of meat quality traits in relation to the physicochemical characteristics of M. rectus abdominis. The heifers of the same trade class were slaughtered at 33 months of age (±4 months) and 381 kg carcass weight (±31 kg). Muscle and bone development scores were evaluated before slaughter. Carcass weight, slaughter age and life average daily gain were recorded. Shear force measurements and meat quality traits were evaluated after 14 days of aging. Some physicochemical characteristics were measured 24 h post-slaughter.Tenderness was correlated with slaughter age (r = −0.31), bone development (r = −0.22) and life average daily gain (r = +0.37). Tenderness was significantly related to total collagen content (r = −0.24), lipid content (r = +0.27) and I myosin heavy chain proportion (r = +0.24). Juiciness was positively correlated with lipid content (r = +0.31) and I myosin heavy chain proportion (r = +0.20). Flavor intensity was correlated with lipid content (r = +0.26) and mean fiber area (r = +0.24). Shear force was correlated with total collagen, lipid and 27K proteasome sub-unit contents. Taking animal characteristics and muscle properties together in a multiple regression analysis increased the explained tenderness variability to 33%. The independent variables listed in order of importance were life average daily gain, total collagen content, bone development, lipid content, I myosin heavy chain isoform proportion, shear force of broiled meat and slaughter age.     

Prevalence and concentration of verocytotoxigenic Escherichia coli,Salmonella enterica and Listeria monocytogenes in the beef production chain: A review

This review examines the prevalence of three important pathogens, verocytotoxigenic Escherichia coli (VTEC), Salmonella enterica and Listeria monocytogenes, in cattle and beef from the farm to the final, ready-to-eat product. Factors affecting prevalence of pathogens in the beef chain, such as the season and cattle rearing method, are examined. Data from many key surveys are summarized in table form.     

Survival of Escherichia coli O157:H7 and non-pathogenic E. coli on irradiated and non-irradiated beef surfaces

This study examined changes in numbers of pathogenic (PEC) and non-pathogenic (NPEC) Escherichia coli during storage at 10 °C on the surfaces of irradiated (IR) and non-irradiated (NIR) meat pieces excised from the neck, brisket and rump of beef carcasses and in Brain Heart Infusion Broth (BHI) and Maximum Recovery Diluent (MRD). On irradiated meat pieces, there were significant differences between mean PEC and NPEC counts at all sites. Differences in counts were also observed between IR and NIR surfaces and among the three meat sites for both E. coli types. These differences occurred only on IR samples, suggesting that the irradiation associated reductions in normal beef surface flora influenced survival of both E. coli types. PEC and NPEC counts increased during storage in BHI, but only NPEC counts increased in MRD. The results of this study highlight the impact of meat surface type and the presence/absence of the normal beef carcass surface flora on E. coli survival and/or growth during meat storage. Such previously unreported effects, and their precise mechanisms, have direct implications in the development and application of accurate models for the prediction of the safety and shelf life of stored meat.     

Evaluation of the performance of osmotic dehydration sheets on freshness parameters in cold-stored beef biceps femoris muscle

This study aimed to evaluate the effects of osmotic dehydration sheet (ODS) packaging on the quality parameters of beef biceps femoris muscle samples stored at 4 °C for 0, 1, 3 and 7 days. Quality indices such as Hunter color values (L^∗, a^∗ and b^∗, the percentage of metmyoglobin (Met-Mb%), K value (freshness index), and the contents of adenosine triphosphate (ATP)-related compounds (ARCs), thiobarbituric acid reactive substances (TBA-RS) and volatile basic nitrogen (VBN) were measured. ODS gave lower a^∗ and b^∗ values and lower Met-Mb% compared with control samples wrapped in polyvinylidene chloride film (PVDCF) (P < 0.01), but had no effect on L^∗ (P < 0.01). As a result, with higher levels of osmotic dehydration produced by the ODS, the percentage of weight loss and the total contents of ARCs and inosine monophosphate of the samples also increased (P < 0.05). The K values of ODS samples were also significantly lower than PVDCF-wrapped samples (P < 0.05). Low performance ODS wrapping reduced the TBA-RS values below those found with PVDCF and high performance ODS processing (P < 0.01). Moreover, the use of ODS had no effect on VBN values. Thus, although the bright red of beef samples changed to a dark purple color and the weights of samples decreased, the ODS approach has potential as a tool for decreasing the deterioration of other quality indices such as Met-Mb%, TBA-RS, ARCs, K values and the VBN content of cold-stored beef.     

Effects of diet and storage on fatty acid profile,micronutrients and quality of muscle from German Simmental bulls

This study evaluated the effect of diet on fatty acid profile, vitamins, trace elements, lipid peroxidation, and quality of longissimus muscle of German Simmental bulls. The effect of storage on fatty acid profile and vitamins was also included. A control group was fed concentrate including soybean, and maize silage/grass silage. Treatment group I (unrestricted) was fed concentrate including rapeseed, and grass silage. Treatment group II (restricted) was fed like treatment group I with a feed restriction period. The treatment diet was not effective to give similar daily live weight gain to the control diet, but it was successful in improving beef fatty acid composition without affecting tenderness and colour (under unrestricted conditions). There were no differences in vitamins and cooking loss, but selenium decreased in treatment groups. Stimulated lipid peroxidation, in samples taken immediately post-mortem, was higher in treatment groups. Polyunsaturated fatty acids decreased, saturated fatty acids and intramuscular fat increased after 14 days of storage while vitamins had no significant reduction.     

Using reflectance spectroscopy to predict beef tenderness

A study was conducted to determine if reflectance measurements made in the near-infrared region of the spectrum were additive to reflectance measurements made in the visible region of the spectrum for predicting Warner–Bratzler shear force (WBSF) values. Eighty seven strip loins were collected following fabrication over 3 d at a commercial beef processing facility from heifer carcasses with Slight or Traces marbling scores. Spectroscopic measurements were made at approximately 50 h postmortem using a Hunter-Lab UltraScan. Subsequently, all strip loins were aged for 14 d, cooked to an internal temperature of 70 °C, and sheared to obtain WBSF values. Reflectance measurements obtained in the near-infrared region of the spectrum were correlated with WBSF values, however, these measurements were not additive to the predictive ability of reflectance measurements (R² values did not differ) made in the visible portion of the spectrum when the use of broad-band wavelength filters were simulated. It was therefore determined, that both the visible and near-infrared spectra measure reflectance and that both methods are acceptable methods of tenderness prediction.     

Consumer acceptability and physiochemical characteristics of modified atmosphere packed beef steaks

The objective of this study was to investigate the physiochemical changes of beef steaks packed under various combinations of gasses and the relationship between consumer perception of flavour and acceptability of modified atmosphere packed beef steaks during retail display. Experimental gas atmospheres included: 40%, 50%, 60%, 70%, and 80% oxygen, with all packs containing 20% CO₂ and the make up gas N₂. Steaks were stored at 4 °C for 12 days and tested for lipid and protein oxidation, heme iron, colour, oxymyoglobin concentration, Warner–Bratzler shear force (WBSF) and consumer acceptability for the resulting cooked meat. The results from 134 consumers indicated a directional preference for the steaks stored in packs containing 40% and 80% oxygen. Samples with high oxygen levels, particularly the O₂60 and O₂70 treatments, were positively and significantly (P < 0.01) correlated to sensory toughness, and significantly (P < 0.05) negatively correlated to juiciness, as determined by consumers. However, the O₂40 samples were most negatively (P < 0.001) correlated to toughness and positively (P < 0.01) correlated to juiciness, which shows that, in general, these higher O₂ levels, >40%, imparted greater meat toughness as determined by the consumers. The greater directional acceptance of the O₂40 samples may be linked to the consumer perceived reduction in sensory toughness and increases in juiciness.