The combined effects of superchilling and packaging on the shelf life of lamb

The aim of this study was to evaluate the effect of superchilled storage at -1° on the shelf life of lamb slices packaged in an O₂ enriched (40% O₂/30% CO₂/30% Ar) or in an anaerobic atmosphere (vacuum skin packaging). Physicochemical, microbial and sensory analyses were performed. The effect of superchilled storage on lamb stability differed depending on the atmosphere surrounding the product. Superchilled (-1°C) slices of lamb showed lower microbial counts than those refrigerated at 4°C in both packaging conditions. Moreover, meat stored at -1°C had a higher colour stability under vacuum. Superchilled storage combined with an O₂ enriched atmosphere increased the rate of lipid oxidation, which reduced the shelf life reached by refrigerating at 4°C. Vacuum skin packaging strongly inhibited lipid oxidation independently of storage temperature. Thus, superchilled storage extended the shelf life at least twice compared to storage at 4°C under anaerobic conditions while it was disadvantageous when an O₂ enriched atmosphere was used.

Effect of Lactic Acid Bacteria on Beef Steak Microbial Flora Stored Under Modified Atmosphere and on Listeria Monocytogenes in Broth Cultures

Beef steaks were inoculated with one or other of two protective strains of lactic acid bacteria, the bacteriocinogenic Lactobacillus sakei CTC 372 or the uncharacterised Lactobacillus CTC 711. They were stored under modified atmospheres (20–40% CO2). Inoculation of meat with both strains inhibited the growth of the spoilage bacteria. Neither CO2 in the pack atmosphere, inoculation with protective strains, nor a combination of both, affected formation of metmyoglobin or the development of off-odours. The formation of metmyoglobin in meat pigments and the sensory odour scores were compatible to those of fresh meat which had not undergone either oxidative deterioration or microbial spoilage. Listeria monocytogenes were inhibited in broth by meat surface microbiota containing either of the protective strains. With an initial population of 5.6 log cfu/mL, after 7 days incubation at 3°C, Listeria monocytogenes were recovered at log mean population of 2.8 log cfu/mL when neither protective strain was present. At 8°C, the population of Listeria monocytogenes recovered were reduced by about 2.5 or 1.5 log cfu/mL in the presence of Lactobacillus sakei CTC 372 or Lactobacillus CTC 711, respectively. At 25°C, the population of Listeria monocytogenes recovered from broth containing either protective strain were about 5 log cfu/mL less than the population recovered from broth containing Listeria monocytogenes only.

Combined Effect of Modified Atmosphere Packaging and Addition of Lycopene Rich Tomato Pulp, Oregano and Ascorbic Acid and Their Mixtures on the Stability of Beef Patties

Beef patties were treated with ascorbic acid, oregano extract, lycopene rich tomato pulp (LRTP) and their mixtures, packaged in modified atmosphere and stored at 2°C. Lipid oxidation (TBARS formation), metmyoglobin formation, psychrotrophic bacterial counts and sensory odour and discolouration were analyzed throughout 20 days of storage. TBA values of beef patties containing oregano were the lowest ( p < 0.05); those containing ascorbic acid and LRTP alone were also significantly lower ( p < 0.05) than the control. The formation of surface metmyoglobin was significantly delayed ( p < 0.05) by the addition of oregano alone and its mixtures with ascorbic acid and/or LRTP. Psychrotrophic bacterial counts were significantly lower ( p < 0.05) in patties treated with 500 ppm oregano. Sensory colour and odour characteristics of beef patties were in agreement with the results of lipid and pigment oxidation. The antioxidant ability of oregano was dependent on the concentration; the presence of 500 ppm extended the shelf life of beef patties by about 8 days. LRTP alone exerted a limited antioxidant effect, while its combination with oregano resulted in a reduction of the antioxidative effect of the latter.

Consumer Beliefs and Attitudes Towards Dry-cured Ham and Protected Designation of Origin Teruel Ham in Two Spanish Regions Differing in Product Knowledge

This work compared the responses of a consumer survey on beliefs and attitudes towards dry-cured ham and protected designation of origin (PDO) Teruel ham carried out in two Spanish regions differing in Teruel ham knowledge: Aragon (high knowledge) and Catalonia (lower knowledge). Results revealed that only small differences were found regarding dry-cured ham consumption habits. With regard to beliefs related to factors affecting ham quality, differences were even lesser; raw material and maturing process, as well as marbling, colour and flavour and proper saltiness were rated as the most important quality factors. Nevertheless, large significant differences were evident between both regions in knowledge, consumption, beliefs and attitudes towards PDO Teruel ham. However, there were no differences regarding the willingness to pay a higher price for PDO ham. Multiple correspondence analysis of all data revealed large effects of age, education, income level and size of the place of residence, independent from the region of origin of the consumer.

The effects of ascorbic acid, taurine, carnosine and rosemary powder on colour and lipid stability of beef patties packaged in modified atmosphere

This research was aimed at evaluating the inhibition of oxidative changes of beef patties packaged in modified atmosphere (70% O(2)+20% CO(2)+10% N(2)) by natural antioxidants: ascorbic acid (500 ppm), taurine (50 mM), carnosine (50 mM), rosemary powder (1000 ppm) and their combinations with the first. Beef patties stored at 2±1°C for 20 days were evaluated for colour (L*, a*, b*, C* and H*), TBARS, metmyoglobin formation (% of total myoglobin), psychrotrophic microbial counts and sensory odour and discolouration. Rosemary, either alone or with ascorbic acid, was highly effective in inhibiting both metmyoglobin formation and lipid oxidation; sensory analysis was in agreement with these results. Ascorbic acid, ascorbic acid+taurine and ascorbic acid+carnosine treatments showed a limited inhibitory effect of myoglobin oxidation, while carnosine and carnosine+ascorbic acid were effective in inhibiting lipid oxidation. Taurine alone failed to exert any antioxidant effect. Principal components analysis confirmed these results.

Chemical composition and antimicrobial effects of essential oils of Eucalyptus globulus, Myrtus communis and Satureja hortensis against Escherichia coli O157:H7 and Staphylococcus aureus in minced beef

Essential oils (EOs) extracted by hydrodistillation from leaf parts of Algerian Eucalyptus globulus, Myrtus communis and Satureja hortensis were analyzed by gas chromatography/mass spectrometry (GC/MS). The main components of EOs obtained were γ-terpinene (94.48%), 1,8-cineole (46.98%) and carvacrol (46.10%), respectively, for E. globulus, M. communis and S. hortensis. The in vitro antimicrobial activity of the EOs was evaluated against Staphylococcus aureus CECT 4459 and Escherichia coli O157:H7 CECT 4267 using the agar diffusion technique. Results revealed that E. globulus and S. hortensis EOs had more antibacterial effects than that from M. communis. Minimal inhibitory concentrations (MIC) showed a range of 0.05-0.22% (volume by volume [v/v]). Sensitivity of gram-positive S. aureus was much higher than that of gram-negative E. coli. Plant EOs were added to minced beef (two-fold MIC value) at 0.10-0.44%, experimentally inoculated with the same pathogens at a level of 5 × 10(5) colony forming units (cfu)/g and stored at 5 ± 2 °C. Results showed that the EOs of E. globulus and S. hortensis had remarkable antibacterial properties, higher than that of M. communis, against S. aureus and E. coli. Indeed, a reduction of 5.8 log cfu/g (70.74% of reduction) was recorded after 7 days of storage for S. hortensis against E. coli. However, regarding S. aureus, both S. hortensis and E. globulus caused a highly significant (p < 0.05) decrease of microbial counts, most evident after 5 days of storage; S. aureus numbers were 3.50 and 2.50 cfu/g, respectively, corresponding to a reduction of 2.20 and 3.20 log cfu/g (38.60 and 56.14% of reduction) after 1 week of storage. Sensory evaluation revealed that the aroma of minced beef meat treated with EOs was acceptable by panelists at the levels used.

Risk factors for advanced lesions undetected at prior colonoscopy: not always poor preparation

BACKGROUND AND STUDY AIM

Colonoscopy is regarded as the gold standard for diagnosis of colonic lesions. However, adenoma miss rates in tandem colonoscopy studies vary from 2 % to 26 %. We aimed to investigate the rates of advanced neoplasia in patients with a prior normal colonoscopy in an outpatient endoscopy unit.

METHODS

Review of reports for colonoscopies performed in our Endoscopy Unit from 2000 to 2005. Undetected lesions were defined as advanced adenoma or colorectal cancer (CRC) not reported in a colonoscopy performed in the previous 2 or 3 years, respectively. Patients with hereditary nonpolyposis CRC (HNPCC) and familial adenomatous polyposis (FAP) were excluded.

RESULTS

Between 2002 and 2005, 795 patients were diagnosed with at least one advanced adenoma and 386 with CRC. Among these, 107/795 patients (13.5 %) had advanced adenoma that had been undetected in a previous colonoscopy (39 % [53/135 lesions] in the right colon); 92/107 (86 %) had an undetected advanced adenoma ≥ 10 mm. Previously undetected CRCs were found in 27/386 patients (6.7 %), located in the left colon in 21/27 (78 %); in 7 the area had not been reached in the previous colonoscopy. Risk factors for undetected advanced adenoma were advanced age, male gender, the presence of another advanced adenoma at first colonoscopy, and history of advanced neoplasia.

CONCLUSIONS

Failure to detect advanced neoplasia is common in a community-based endoscopy facility. Previously undetected advanced lesions are more frequently found in the left colon and rectum. Risk factors for non-detection of advanced adenoma are similar to those for advanced neoplasia recurrence. Lowering non-detection rates is crucial for correct follow-up recommendations. Patients should be aware of rates of detection of advanced neoplasia after previous normal colonoscopic findings.

Preservation of the proteolytic activity of a bovine spleen lysosomal-enriched extract using various freezing conditions

The preservation of the proteolytic activity of a bovine spleen lysosomal-enriched (BSLE) extract was investigated. The BSLE extract (pH = 5.8), was subjected to storage under different conditions: refrigeration at 0 degrees C for 60 days; freezing at -20 degrees C -either directly or previously frozen in liquid nitrogen-, -80 degrees C and in liquid nitrogen; freeze-drying and stored at 0 degrees C; and freezing at -20 degrees C or in liquid nitrogen in the presence of glycerol and sorbitol as cryoprotectants. Freezing at low temperatures (-80 degrees C and in liquid nitrogen) was most effective for preserving about 100% of the initial activity of all cathepsins (B, B+L and D), as well as the activity of the extract on myofibrils, for two years. Freezing at -20 degrees C, on the contrary, led to significant (P < 0.01) losses of activity. Freeze-drying was able to preserve cathepsin activity, while it failed to maintain activity on myofibrils. Both cryoprotectants sorbitol and glycerol significantly (P < 0.01) enhanced enzyme preservation, particularly cathepsin D and the activity on myofibrils, even at a freezing temperature of -20 degrees C.

Direct and highly species-specific detection of pork meat and fat in meat products by PCR amplification of mitochondrial DNA

Highly species-specific primers for pork D-loop mtDNA have been designed. Use of these and restrictive PCR amplification conditions has improved a reliable and rapid method for detecting a PCR-amplified 531 bp band from pork. It has been proved useful for detecting both pork meat and fat in meat mixtures, including those dry-cured and heated by cooking. Absence of response in PCR-amplified samples or mixtures from bovine, ovine, chicken, and human was also demonstrated. Furthermore, wild boar and pork samples can be also easily distinguished by a simple AvaII restriction analysis.

Ultrasonication of lamb skeletal muscle fibres enhances postmortem proteolysis

The effect of ultrasound upon the postmortem proteolytic activity of muscle fibres was investigated. As a preliminary result it was demonstrated that ultrasonication released lysosomal enzymes from liver cells while cell membranes suffered little damage. Proteolysis brought about by endogenous proteinases after 2 days of fibre storage at 4 degrees C was assessed by means of sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). Ultrasonic treatment of fibres enhanced proteolytic activity, as shown by the increased intensity of 30-kDa region degradation bands. A distinct change featuring sonicated fibres was the degradation of an 87-kDa protein and the appearance of an 83-kDa peptide. Cell damage was not very extensive, although it depended upon ultrasonication and fibre conditions.

Proteolytic activity of isolated lamb calpains on myofibrils under the conditions of pH, Ca2+ concentration and temperature existing in postmortem muscle

The two calcium-activated neutral proteinases (calpains I and II) and their specific inhibitor were isolated by ion exchange chromatography in DEAE-Sephacel from lamb skeletal muscle (longissimus dorsi). Their proteolytic activities were then determined using myofibrils as substrate. The Ca2+ requirements were different for each form of the enzyme: calpain I needed only 50 mumol Ca2+ for half-maximal activity, while the other isoenzyme, calpain II, needed 1,000 mumol Ca2+ for reaching 50% of its maximum activity. Both calpains showed a relevant activity in the pH range 5.5-6.5 (over 40% of maximum activity found at pH 7.5). With regard to the effect of temperature, both isoenzymes retained about 25% of their activity at 25 degrees C with a temperature reduction down to 4 degrees C. It is concluded that calpain I is an active protease under conditions similar to that prevalent in lamb meat during postmortem storage.

Bisphosphoglycerate synthase activity in cells of the erythrocytic line of rat

The specific activity of bisphosphoglycerate synthase (EC 2.7.5.4) is significantly higher in rat mature erythrocytes than in reticulocytes from phenylhydrazine treated animals, while 2,3-bisphosphoglycerate levels do not differ between them. The enzyme specific activity and the concentration of 2,3-bisphosphoglycerate are both negligible in the erythroid cell pool from the bone marrow of anaemic animals. Thus, a cellular specialization in the last stages of erythropoiesis is confirmed. Human bisphosphoglycerate synthase shows a lower specific activity than that of rat without a parallel decrease in 2,3-bisphosphoglycerate levels.