自然发酵肉制品中乳酸菌的分离及特性研究

以MRS和改良TJA(改良番茄汁琼脂培养基)培养基为基础培养基,从自然发酵肉品中分离得到8个菌株,其中4株为乳酸菌,3株为杆菌,1株为球状菌。进一步测试表明:4株乳酸菌在30℃培养时,生长最好;在pH3.5～4.0时生长良好;4株乳酸菌在10%NaCl的环境中均能生长,其中以2%～6%的NaCl浓度内生长最适宜;属兼性厌氧菌;对大肠杆菌产生一定的抑制作用。分离出的4株乳酸菌均适宜作为发酵肉制品的发酵剂。     

Identification of staphylococci and dominant lactic acid bacteria in spontaneously fermented Swiss meat products using PCR-RFLP

Pathogenic, spoilage, and technologically important microorganisms were monitored in 21 spontaneously fermented Swiss meat products manufactured with meat from wildlife or animals grown in natural habitat. Thereby, PCR-restriction fragment length polymorphism (RFLP) on rpoB and 16S rRNA gene sequences provided a powerful tool for fast and accurate identification of the main microbial population. Lactobacillus sakei and Lactobacillus curvatus dominated in fermented meat products followed by Staphylococcus species, which constituted 88.2% of all Gram-positive, catalase-positive cocci (GCC⁺) with cell counts varying from 2.6 to 7.0 log cfu/g during maturation. Staphylococcus equorum was prevalent in frequency and cell counts during maturation (18.0%; 5.0-7.3 log cfu/g) and in the end products (28.4%; 1.8-6.2 log cfu/g) implicating a new presumptive starter species for meat fermentation. Nine out of 14 end products indicated safety risks to consumers due to the high incidence of Staphylococcus saprophyticus or Staphylococcus epidermidis combined with cell counts of 7.4 and 4.9 log cfu/g, respectively. This fact was supported by the detection of Staphylococcus aureus and Enterobacteriaceae in ready-to-eat products strongly exceeding the tolerable limit of 2 log cfu/g. Spontaneously fermented meat products produced from wildlife or animals grown in natural habitats not only gave rise to hygienic and safety concerns but also provided new presumptive starter strains.     

Difference in tenderness and pH decline between water buffalo meat and beef during postmortem aging

The objective of this research was to determine the difference in tenderness and some characteristics of water buffalo meat and beef during postmortem aging. Five female crossbred water-buffalo (Philippine Carabao×Bulgarian Murrah) and five female crossbred cattle (Brahman×Philippine Native), were finished on the same diet for 6 months and slaughtered at 30 months of age. The muscle pH was measured at 40min, 3h, 7h, 24h, and 48h postmortem. Longissimus thoracis (LT) and semimembranosus (SM) muscles were excised at 2d postmortem, and shear force was measured at 2, 4, 7, and 14d postmortem. Glycogen and lactate concentrations were determined from 0, 2, and 4d LT samples, and myosin heavy chain type of buffalo and cattle LT was determined by ELISA methods. Myofibrillar protein degradation was also observed by SDS-PAGE and Western blotting of fast-type troponin T. Results showed that the buffalo meat had significantly lower shear force values compared to beef for LT and SM muscles, which was supported by a difference in troponin T degradation. Postmortem pH decline of buffalo meat was significantly slower than that of beef, which was confirmed by lactic acid concentrations, but was not explained by glycogen content. In addition, there was no significant difference in the ratio of slow to fast type muscle fibers in buffalo and cattle, indicating that myosin heavy chain type was not responsible for the difference in pH decline and tenderness between the buffalo meat and beef. This study demonstrated that the tenderness of water buffalo meat was superior to that of Brahman beef, which may have been due to the difference in pH decline and the subsequent effect on muscle protease activity.     

Relationship between the solubility,dosage and antioxidant capacity of carnosic acid in raw and cooked ground buffalo meat patties and chicken patties

Antioxidant capacity of oil soluble and water dispersible carnosic acid (CA) extracted from dried rosemary leaves using HPLC was evaluated at two different dosages (22.5 ppm vs 130 ppm) in raw and cooked ground buffalo meat patties and chicken patties. Irrespective of total phenolic content, CA extracts reduced (p < 0.05) the thiobarbituric acid reactive substances (TBARS) by 39%–47% and 37%–40% in cooked buffalo meat and chicken patties at lower dosage (22.5 ppm) relative to control samples. However, at higher dosage (130 ppm) the TBARS values were reduced (p < 0.05) by 86%–96% and 78%–87% in cooked buffalo meat and chicken patties compared to controls. The CA extracts were also effective in inhibiting (p < 0.05) peroxide value and free fatty acids in cooked buffalo meat and chicken patties. The CA extracts when used at higher dosage, were also effective in stabilizing raw buffalo meat color.     

Effect of ammonium hydroxide on ultrastructure and tenderness of buffalo meat

This study was conducted with an objective to improve the tenderness of tough buffalo meat using ammonium hydroxide. Buffalo meat chunks from Biceps femoris muscle were marinated with distilled water (control), 0.1%, 0.5% and 1.0% solution of ammonium hydroxide for 48 h at 4±1 °C and subjected to various physico-chemical analysis and ultrastructural studies. Ammonium hydroxide increased (P<0.05) the pH, water holding capacity (WHC), collagen solubility, total and salt soluble protein extractability and cooking yield. Reduction (P<0.05) in Warner-Bratzler shear force values were observed in all ammonium hydroxide treated samples compared to non-treated control. Electrophoretic pattern of muscle proteins exhibited reduction in the intensity and number of certain protein bands for 0.1% and 0.5% ammonium hydroxide treated samples compared to control. Scanning and transmission electron microscopy also revealed breakdown of endothelium layers surrounding muscle fibers and weakening of Z-discs respectively, in treated samples compared to controls. These results suggest that ammonium hydroxide might be used to tenderize tough buffalo meat.     

Improvement of lipid stability of rabbit meat by vitamin E and C administration

The effect of administering vitamins E (E₅₀ or E₂₀₀: 50 or 200 mg kg diet) and C (C₅₀₀ or C₁₀₀₀: 500 or 1000 mg l⁻¹ water) singly and in combination was verified on plasma and muscle levels of α‐tocopherol and the oxidative stability of rabbit meat during display. Six groups of 10 hybrid males were fed experimental diets from 35 to 85 days of age. Productive performance and carcass drip loss were also recorded. Performance was unaffected by treatments, but drip loss was improved by simultaneous administration of the two antioxidants. The α‐tocopherol levels in plasma and muscle were significantly higher in animals which simultaneously ingested the highest amounts of the two vitamins, and the oxidative processes (TBA‐RS values) of their meat during storage were lower. The results confirm the synergistic action of ascorbate and the benefit of using high levels of the two vitamins to prevent oxidative stress during meat processing and storage. © 2000 Society of Chemical Industry     

乳酸菌肉品发酵剂的选择

从发酵肉制品中分离、纯化乳酸菌132株,对它们的主要发酵特性进行了测定,以生产干发酵香肠誓前篓,从中选出4株乳酸菌优选菌株R17、P20、P30和J33。4株菌生长速度有显著差异,温度对其生长速度有显著的影响。其中R17和P20之间没有拮抗关系,可以作为混合发酵剂。P30和J33可以作为单菌发酵剂。     

Unexpected sources of vitamin C

Sausages are quite common in the Norwegian diet. Presently the vitamin C content in sausages is listed as zero in the Norwegian Food Composition Table as well as in several other countries’ food composition tables. In the present study, five different kinds of sausages were analysed for relevant nutrients including vitamin C. One composite sample consisting of 15–16 subsamples was analysed for each sausage type. Vitamin C was measured by high-performance liquid chromatography (HPLC) with electrochemical detection as the sum of l-ascorbic acid and dehydro-ascorbic acid. The vitamin C content in the analysed sausages varied from 11 to 40 mg/100 g. This is explained by addition of vitamin C as an antioxidant by the manufacturer mainly to preserve colour. When recalculating vitamin C intakes from the most recent Norwegian national dietary surveys in adults, children and youths using the updated vitamin C values, total vitamin C intake increased by 3–10%. Other processed meat products such as cold cuts may also contain vitamin C as an antioxidant, and a larger impact on vitamin C intake may be seen if also these products turn out to contain considerable amounts of vitamin C. When planning analytical projects for food composition databases, care should be taken to include vitamin C for products where this vitamin may have been added for antioxidant purposes.     

Shelf life and stability traits of traditionally and modified atmosphere packaged ground beef patties treated with lactic acid bacteria, rosemary oleoresin, or both prior to retail display

Previous research indicates that lactic acid bacteria (LAB) can inhibit pathogenic bacteria. This research evaluated effects of LAB inclusion on the shelf life of traditionally packaged ground beef patties; as well as the effects and possible interaction of LAB and rosemary oleoresin (RO) on the stability of high oxygen MAP ground beef during display. In both package types, trained and consumer evaluations indicated no effect (P > 0.05) of LAB on lean color and off-odor. Display affected trained and consumer sensory evaluations and indicated declined stability over time. Thiobarbituric acid values were lower for traditionally packaged ground beef with LAB (P < 0.05) and MAP ground beef with RO or RO and LAB (P < 0.05). Overall, LAB had no effect on the shelf life and stability of traditionally or high-oxygen MAP packaged ground beef patties. Therefore, utilization of LAB in ground beef to reduce pathogenic bacteria is viable without alteration of spoilage indicators.     

乳酸菌液态发酵兔肉的研究

采用乳酸菌液态发酵法泡制免肉，研制出一种具有泡菜风味的兔肉食品。     

Effect of age and gender on the processing characteristics of buffalo meat

Comparison of processing characteristics of meat from young male, spent male and spent female buffaloes was made to find the suitability of the meat for developing ready to eat meat products. Intensively reared young male buffalo meat showed higher moisture, collagen solubility, sarcomere length, myofibrillar fragmentation index and water holding capacity than meat from the other animals. A higher pH, total meat pigments, salt soluble protein, emulsifying capacity and lower collagen solubility were observed in spent male buffalo meat. Spent female buffalo meat had higher fat, total collagen, muscle fibre diameter and shear force value. Sensory evaluation of pressure cooked meat chunks indicated a marked toughness in spent male and female buffalo meat samples. These results suggest that young male buffalo meat is more suitable for processing in chunks and spent male and female buffalo meat is more suitable for processing in smaller particles.     

Effect of comminution temperature on the quality and shelf life of buffalo meat nuggets

Buffalo meat nuggets were prepared after equilibrating the ingredients to temperatures of 4, 10, 25 and 37 °C. Following comminution for 6 min, the temperatures of the batters were 16.3, 19.3, 27.4 and 34.8 °C and their pH and emulsion stability ranged from 6.18 to 6.29 and 88.76 to 95.33%, respectively. Increasing temperature of comminution led to increased cooking losses and TBARS values. However, even at 37 °C, complete emulsion breakdown did not occur as the cooking losses were still only about 12%. Texture profile analysis revealed an inverse relationship between chopping temperature and shear force. Sensory evaluation indicated that, at least up to comminution temperatures of 27.4 °C, the nuggets were acceptable. The aerobic mesophilic bacterial counts were higher for the nuggets made from batters with higher temperatures but, even at the 21st day of storage, the counts were well below the levels likely to cause spoilage in meat products. Results suggested that comminuted buffalo meat products can be manufactured in conditions where refrigeration is not available, by a preservation system (mostly chemical) to decrease microbial and chemical spoilage and also by devising an efficient marketing system for their early distribution (preferably 14 days).     

Effects of salt and ammonium hydroxide on the quality of ground buffalo meat

The objective of this study was to evaluate the effects of ammonium hydroxide (AH) and sodium chloride on the quality of ground buffalo meat patties. Ground buffalo meat was treated with distilled water (control), 0.5% v/w AH, 1.0% v/w AH, 2.0% v/w AH and 1.0% w/w sodium chloride was added for all the samples. Treatment with AH increased (P<0.05) the pH and water holding capacity (WHC) of ground buffalo meat patties during storage relative to their controls. Hunterlab a* (redness) and chroma values increased (P<0.05) and hue decreased (P<0.05) in all AH treated samples in comparison to controls during storage. Ammonium hydroxide significantly (P<0.05) inhibited metmyoglobin formation compared to control after 3rd day of storage. There was a significant (P<0.05) reduction in thiobarbituric acid reactive substances (TBARS) values in all AH treated samples compared to control throughout storage. These results indicate the potential antioxidant and myoglobin redox stabilizing effect of AH in ground buffalo meat patties.     

Diversity of lactic acid bacteria from modified atmosphere packaged sliced cooked meat products at sell-by date assessed by PCR-denaturing gradient gel electrophoresis

The predominant lactic acid bacteria (LAB) microbiota associated with three types of modified atmosphere packaged (MAP) sliced cooked meat products (i.e. ham, turkey and chicken) was analyzed at sell-by date using a combination of culturing and molecular population fingerprinting. Likewise routine analyses during industrial MAP production, meat samples were plated on the general heterotrophic Plate Count Agar (PCA) and on the LAB-specific de Man, Rogosa, Sharpe (MRS) agar under different temperature and atmosphere conditions. Subsequently, community DNA extracts were prepared from culturable bacterial fractions harvested from both media and used for PCR targeting the V3 hyper-variable region of the 16S rRNA gene followed by denaturing gradient gel electrophoresis (DGGE) of PCR amplicons (PCR-DGGE). Irrespective of aerobic or anaerobic incubation conditions, V3-16S rDNA DGGE fingerprints of culturable fractions from PCA and MRS medium displayed a high level of similarity indicating that LAB constituted the most dominant group in the culturable bacterial community. Comparison of DGGE profiles of fractions grown at 20, 28 or 37 °C indicated that part of the culturable community consisted of psychrotrophs. Four DGGE bands were common among cooked ham, turkey and chicken products, suggesting that these represent the microbiota circulating in the plant where all three MAP product types were sliced and packaged. Based on band sequencing and band position analysis using LAB reference strains, these four bands could be assigned to Lactobacillus sakei and/or the closely related Lactobacillus fuchuensis, Lactobacillus curvatus, Carnobacterium divergens and Leuconostoc carnosum. In conclusion, the PCR-DGGE approach described in this study allows to discriminate, identify and monitor core and occasional LAB microbiota of MAP sliced cooked meat products and provides valuable complementary information to the current plating procedures routinely used in industrial plants.     

发酵马肉中乳酸菌的分离筛选与鉴定

从发酵马肉中分离纯化出7株乳酸菌,对它们的主要发酵特性如耐盐、耐硝、产黏液、产气等进行了测定,并比较了它们在不同温度下的生长和产酸情况以及发酵过程中的pH变化,发现其中3株乳酸菌具有较好的发酵特性,如生长快、产酸快,能够耐6%NaCl、耐150mg/kgNaNO2,不产气、不产氨,H2O2实验、H2S实验、V-P反应均为阴性等,符合发酵肉制品生产菌种的要求,经形态观察和碳源利用实验,初步鉴定其中2株为肉杆菌、1株为德氏乳杆菌。     

发酵肉制品中乳酸菌的主要发酵特性

从发酵肉制品中分离、纯化乳酸菌132株,对它们的主要发酵特性如耐盐性、耐硝性、产黏液、产气等进行了测定,并比较了它们在不同培养基中的产酸情况。     

Nitrite tolerance and nitrite reduction in lactic acid bacteria associated with cured meat products

The effect of 0, 50, 100 and 200 μg/ml of nitrite on the growth of isolated and reference strains of lactic acid bacteria associated with cured meat products was studied in broth cultures and the presence of an active nitrite reductase enzyme system in these strains was determined. Half of the 10 reference strains and 16 of 25 isolated strains were resistant to all levels of nitrite tested Strains which did not show a significant decrease in growth rate or cell yield in the presence of 200 μg/ml of nitrite under anaerobic conditions were homofermentative. All heterofermentative strains showed a decrease in growth rate or cell yield or both. Inhibition due to nitrite increased as the concentration increased and was greatest under anaerobic conditions. Enzymatic ability to reduce nitrite was detected in 5 homofermentative and 1 heterofermentative strains. The presence of an active nitrite reductase enzyme system in lactic acid bacteria was not related to their resistance to nitrite.