Manufacture Of Meat Products Research Articles

Tourist ships on the Danube as an opportunity for export of meat and meat products

Tourism development launches growth of other complementary industries. River tourism, as a special selective tourism form, experiences intensive development, with an importance for all the regions through which the Danube, as an integral part of the Rhine - Main – Danube waterway, flows. During cruising, the largest consumption is achieved on the ship itself, where meat and meat products are an integral element of every meal and represent the most expensive component of the dish. The task of this paper is to analyse the consumption of meat and meat products on six tourist ships run by to “Grand Circle Corporation” in 2013, in order to point out the possibility of supplying them with meat and meat products from sources in the territory where the ships sail. The paper presents the current suppliers and manufacturers of meat and meat products in Republic of Serbia that could supply the company „Grand Circle Cruise Line“ and other tourist ships that cruise on the Danube. Also, the research indicates that the export of meat products from the Republic Serbia could have a signifcant effect on improving the agricultural conditions and food production through increased competition, assuming the Serbian manufacturers supply most of tourist ships and not only the six ships analysed in this paper. Research results, specifcally, point out the possibility of increasing export of poultry and beef if the potential demand of each of the eight companies with their 54 ships which operate tourist cruises on the Danube is taken into account. The data have been systematized, analysed and presented statistically in tables and graphs.

Total Phosphorus Content in Technologically Unprocessed Meat

The total phosphorus content was measured in raw, technologically unprocessed meats. Our results show that total phosphorus content in different raw meats varies substantially (from 1.41g/kg to 4.22 ± 0.93g/kg). Based on the results, manufacturers of meat products are advised that before production of any meat product, the precise amount of total phosphorus in raw meat starting material has to be known. Based on this, the content of added synthetic phosphates and polyphosphates together with the content of natural phosphorus in the meat would be within the prescribed values stated in the Regulation, which are 8g/kg.

Effect of date palm coproducts and annatto extract on lipid oxidation and microbial quality in a pork liver pâté.

Dates are an interesting source of bioactive compounds, and coproducts from the date industry are of potential use in the manufacturing of meat products. In the present research, spreadable pork liver pâtés were made using fresh date coproducts (2.5% and 7.5%) as a potential functional ingredient and an ethanolic annatto extract (128 mg/kg) as colorant. The effect of these 2 ingredients on the lipid oxidation and microbial quality of the pâtés was assessed during 21 d of storage. The pâtés containing 7.5% date paste were seen to have the highest content of phenolic compounds during storage. The combination of 2.5% date paste and annatto protected pâtés against lipid oxidation throughout the 21 d of storage, thiobarbituric acid-reactive substances values being 0.47 mg MDA/kg at the end of this period, while other combinations increased oxidation compared to the control pâté. The control and those made with 2.5% date paste alone showed the highest counts of mesophilic aerobic bacteria, while the addition of annatto and/or 7.5% date paste reduced this count. The results suggest that a combination of both ingredients is necessary to reduce oxidation and microbial growth, but whereas the concentration of 2.5% is more appropriate to reduce oxidation, the combination with 7.5% date paste reduces the microbial counts. Both ingredients could have an opportunity of valorization in the meat industry for improving the quality.

Antioxidant Active Packaging with Soy Edible Films and Oregano or Thyme Essential Oils for Oxidative Stability of Ground Beef Patties

AbstractThe effectiveness of soy‐based edible films (EF) incorporated with essential oils (EO) from oregano (OR, Oreganum heracleoticum L.) or thyme (TH, Thymus vulgaris L.) applied on oxidative stability of ground beef patties (GBP) was investigated at 4C for 12 days. Higher antioxidant activity by OR than TH EO was determined with a 2,2'‐diphenyl‐2‐picrylhydrazyl radical‐scavenging assay. Induction time of oxidation measured with the Rancimat test in lipids of GBP was extended with the addition of EOs to EFs. Lower peroxide and free fatty acidity (P < 0.05) values were determined with OR‐EF or TH‐EF, particularly at later stages of storage. Incorporation of EO from OR or TH into the EFs resulted in reduced, but acceptable, redness (a*) values (P < 0.05) in ground beef. This study suggests that the addition of OR or TH EOs into EFs as an antioxidant active packaging is effective in retarding oxidative changes in meats.Practical ApplicationsOxidation reactions are among the most important factors responsible for loss of quality in meat products. Packaging using edible films (EFs) with the inclusion of natural plant extracts is becoming a promising active packaging approach to control oxidative changes in food products during storage. This study was focused on the inclusion of thyme or oregano essential oils (EOs) into EF formulation to control oxidative changes in ground beef patties. Results indicate that inclusion of EOs as antioxidants into soy‐based EFs offers great potential in industrial applications for controlling oxidative changes in the manufacture of natural meat products.

Effects of pH-Shift Processing and Microbial Transglutaminase on the Gel and Emulsion Characteristics of Porcine Myofibrillar System.

This study investigated the effects of microbial transglutaminase (MTGase) and pH-shift processing on the functional properties of porcine myofibrillar proteins (MP). The pH-shift processing was carried out by decreasing the pH of MP suspension to 3.0, followed by re-adjustment to pH 6.2. The native (CM) and pH-shifted MP (PM) was reacted with and without MTGase, and the gelling and emulsion characteristics were compared. To compare the pH-shifted MTGase-treated MP (PT), deamidation (DM) was conducted by reacting MTGase with MP at pH 3.0. Rigid thermal gel was produced by MTGase-treated native MP (CT) and PT. PM and DM showed the lowest storage modulus (G') at the end of thermal scanning. Both MTGase and pH-shifting produced harder MP gel, and the highest gel strength was obtained in PT. All treatments yielded lower than CM, and CT showed significantly higher yield than PM and DM treatments. For emulsion characteristics, pH-shifting improved the emulsifying ability of MP-stabilized emulsion, while the treatments had lower emulsion stability. PM-stabilized emulsion exhibited the lowest creaming stability among all treatments. The emulsion stability could be improved by the usage of MTGase. The results indicated that pH-shifting combined with MTGase had a potential application to modify or improve functional properties of MP in manufacturing of meat products.

High hydrostatic pressure processing of beef patties: Effects of pressure level and sodium tripolyphosphate and sodium chloride concentrations on thermal and aggregative properties of proteins

Abstract Beef patties added with sodium tripolyphosphate (STPP; 0, 0.25 or 0.5%) and/or NaCl (0, 1 or 2%) were treated at 200 or 300 MPa (5 min, 5 °C) or kept refrigerated (non-pressurized). In non-pressurized patties, NaCl-solubilized proteins were denatured, whereas STPP-solubilized proteins remained in native state. At 200 MPa, myosin head was more sensitive to high hydrostatic pressure (HHP) than actin. 1% NaCl favored HHP-induced denaturation of myosin head and actin, whereas 0.25% STPP protected against that effect. At 300 MPa, STPP favored HHP-induced denaturation of myosin head, actin and other proteins. The effect of STPP at 200 MPa may depend on the presence of specific binding sites for STPP anion, which would be destroyed at 300 MPa. Insoluble aggregates were formed at 300 MPa in samples without salts. Salts minimized protein aggregation was observed at 300 MPa. Noticeable differences in thermal and aggregative behavior occurred whether HHP level was 200 or 300 MPa. Industrial relevance Currently, the reduction of sodium content in the manufacture of meat products is a hot topic and it is expected that this issue will become more relevant in the next years, as response to consumers' demands. Soluble high hydrostatic pressure-denatured beef proteins may provide interesting texture and technological properties to meat products with reduced salt content.

Design, Control and First Monitoring Data of a Large Scale Solar Plant at the Meat Factory Berger, Austria

Within the European FP7 Project InSun, which started in April 2012, three large scale solar plants for industrial processes in three different countries are installed and will be monitored in detail over a period of almost two years. The main idea of InSun is to demonstrate the reliability and quality of large scale solar thermal systems using different types of collectors for the generation of heat employed in different industrial processes.One of these demonstration plants is located in Austria and it is providing heat up to 90°C for the manufacture of meat products in the factory Berger. Zafh.net, the coordinator of the project, developed a dynamic simulation model of this plant, which should be used to improve the control strategy of the real process. After two months of operation, the first monitoring data are available and will be compared with the simulation results. Based on this comparison, key performance figures (e.g. solar yield) could be predicted for the whole lifetime of the plant. Furthermore economical outputs could be calculated more precisely, which provides essential information for the key stakeholders in the industry.

Comparative study of fatty acid composition of meat material from various animal species.

Fatty acid composition of lipid components as a part of recipes of meat products has been investigated. Factors influencing the results of analytical determination of individual fatty acids are shown. The main ratios of fatty acid composition describing fats of sheep, sow, boar, cow, turkey, horse, chicken, pheasant, and wild boar are presented, allowing their use in manufacture of modern meat products with variable nutrition value.

Combined use of high pressure and salt or sodium nitrite to control the growth of endogenous microflora in raw pork meat

Abstract The interaction of high pressure (up to 500 MPa at 20 °C for 6 min) with sodium chloride (0%–3%) or sodium nitrite (0 mg/kg–100 mg/kg) on the outgrowth of four endogenous flora of pork meat was investigated during storage after a cold-chain break. First, the effect of high pressure was investigated. Next, high-pressure treatments at 350 MPa were combined with the addition of salt or sodium nitrite. Interesting results were observed for the lactic acid bacteria of the salted samples. Whereas salt or 350 MPa processing alone was not sufficient to delay the growth of these bacteria until the end of storage, the combination treatment resulted in low microbial counts (below 2 log CFU/g) at the end of storage. The results of this study suggest the existence of a synergy between salt and high pressure that could result from pressure sensitization of bacterial cells. Industrial Relevance Meat products must contain enough hurdles to inhibit the growth of pathogenic or spoilage microorganisms. The existence of synergy between high pressure and salt or nitrite is promising for the manufacture of meat products. In fact, the use of high-pressure processing could be an approach to limit the addition of salt and nitrite while ensuring extended shelf life, as consumers demand simpler and healthier formulations.

Color compensation in nitrite‐reduced meat batters incorporating paprika or tomato paste

Nitrite is a key ingredient the manufacture of meat products, forming a stable pink color characteristic of cured products, retarding the development of rancidity and off-odors and flavors during storage, and preventing microbial growth. The negative aspects of nitrite and the demands for healthy foods result in the need to reduce nitrite in cured meat products. Paprika or tomato has been employed as natural pigments in meat products. The objective of this work was to determine the effect of incorporating paprika powder or tomato paste on the texture, rancidity and instrumental and sensory color compensation in nitrite-reduced meat batters. Addition of tomato paste improved moisture content, resulting in harder but less cohesive samples as compared to control and paprika-containing meat batters. Color characteristics of reduced nitrite samples obtained higher a* red coloration (8.9 for paprika and 7.7-8.0 for tomato paste), as compared to control samples (5.65). Instrumental color was low in control samples, with high values for tomato paste and paprika samples. Nonetheless, tomato paste used to compensate color in nitrite-reduced meat batters was ranked closer to the control sample in sensory evaluation. Color characteristics-instrumental and sensory-in these kinds of meat products were enhanced by the addition of 2.5-3.0% of tomato paste, presenting results close to the non-reduced nitrite control. Similarly, antioxidant components of tomato paste or paprika reduced lipid oxidation. Nitrite reduction from 150 to 100 ppm could be achieved employing tomato paste as a natural pigment to improve color and texture.

Quality traits of wild boar mould-ripened salami manufactured with different selections of meat and fat tissue, and with and without bacterial starter cultures

Quality traits of wild boar mould-ripened salami were assessed in eight batches produced from two different assortments of meat (hind leg vs. shoulder), fat tissue (backfat from domestic pigs vs. fat tissue from wild boar), and with and without addition of a commercial bacterial starter culture. Chemical composition of finished products (day 35) were in compliance with national food codex. Batches produced with a bacterial starter culture were generally preferred by taste panels, had significantly lower concentrations of TBARS (<1.5mgmalondialdehyde/kg) and peroxide values (POVs) and lower concentrations of cadaverine (<50mg/kg), histamine (<10mg/kg) and putrescine (<60mg/kg). TBARS and POVs were inversely related to sensory preference scores (r2=0.84 and 0.88). Batches produced from shoulder muscles contained significantly higher concentrations of cadaverine, histamine and putrescine. TBARS were highest in batches manufactured with fat tissue from wild boars. These findings should be considered when guides to good practice for the manufacture of game meat products are developed.

Characterization of an Amylase-sensitive Bacteriocin DF01 Produced by Lactobacillus brevis DF01 Isolated from Dongchimi, Korean Fermented Vegetable

A DF01 strain that inhibits tyramine-producing Lactobacillus curvatus KFRI 166 was isolated from Dongchimi, a traditional Korean fermented vegetable, and identified as Lactobacillus brevis by biochemical analysis and reverse transcriptase sequencing of 16S rRNA. The antimicrobial compound produced by L. brevis DF01 was secreted at a maximum level of 640 AU/mL in late exponential phase in MRS broth, and its activity remained constant during stationary phase. The activity of bacteriocin DF01 was totally inactivated by <TEX>$\alpha$</TEX>-chymotrypsin, pronase E, proteinase K, trypsin, and <TEX>$\alpha$</TEX>-amylase, but not by catalase, which indicates the compound was glycoprotein in nature. The activity was not affected by pH changes ranging from 2 to 12 or heat treatment (60, 80, and <TEX>$100^{\circ}C$</TEX> for 30 min), but was reduced after autoclaving. Bacteriocin DF01 had bacteriolytic activity and a molecular weight of approximately 8.2 kDa, as shown by tricine-SDS-PAGE analysis. Therefore, bacteriocin DF01 can be used in the manufacture of fermented meat products due to its inhibition of tyramine-producing L. curvatus and non-inhibition of L. sake, which is used as a starter culture for meat fermentation.

GC/MS detection of central nervous tissues as specified BSE risk material in meat products: validation by an externally controlled blind trial

The addition of central nervous tissues (CNT), such as brain and spinal cord, in the manufacturing of meat products is either forbidden--if the material falls under the legal definition of specified risk material (SRM)--or must be labelled on the packed product. To foster official food control, several CNT detection methods were developed, but only fatty acid patterns as detected by gas chromatography/mass spectrometry (GC/MS) allow the further characterization of the detected CNT as to both the animal species and--surprisingly--the age of the animal from which the CNT was derived in accordance with the legal definition. Complementing a previous report in this journal by Lücker et al. 2010 (doi: 10.1007/s00216-010-3956-5) on CNT quantification by GC/MS, we now report results of the validation of this new analytical approach by an externally controlled blind trial elucidating its potential to identify the species and age of the CNT detected. The 72 samples (24 standards of emulsion-type sausage, each heated in three different batches: 75°C, 30 min; 115°C, 25 min; 133°C, 40 min) containing porcine, ovine or bovine muscle tissue and differing amounts of CNT (bovine or ovine brain: 0, 0.1, 0.5, 1.0, 3.0% m/m) were produced externally and provided blind for analyses to our laboratory. In accordance with the previous study, heating had no detectable effect on the GC/MS analysis. Judged by the present sensitivity of this method (cut-off 0.2% CNT), all of the samples containing 0.5% or more CNT (n = 57, 100%) were identified correctly as CNT-positive. The CNT species was identified correctly in 54 samples (94.7%), with three samples of one specific standard (0.5% ovine CNT) falsely classified as bovine CNT. However, the CNT age of these samples was correctly classified (more than 12 months). Overall, 57 samples (100%) were correctly classified as SRM-positive and 15 samples (100%) as SRM-negative. To the best of our knowledge, this is the first time that a legal demand for the (1) detection of traces of a specific tissue in a food matrix, (2) the identification of its taxonomic origin and (3) the classification of its age has been shown to be analytically possible in totally blind samples. The very positive validation results of this externally controlled blind trial recommend the present GC/MS approach for the detection of CNT in meat products as a reference method. However, our results also demonstrate the need for further studies, in particular to increase sensitivity and to conduct ring trials including more than one laboratory.

Characterization of Selected Wild Mediterranean Fruits and Comparative Efficacy as Inhibitors of Oxidative Reactions in Emulsified Raw Pork Burger Patties

In the present study, water, ethanolic, and methanolic extracts from seven selected wild fruits originally from the Mediterranean area, namely, strawberry tree ( Arbutus unedo L., AU), azarole ( Crataegus azarolus L., CA), common hawthorn ( Crataegus monogyna L., CM), blackthorn ( Prunus spinosa L., PS), dog rose ( Rosa canina L., RC), elm-leaf blackberry ( Rubus ulmifolius Schott, RU), and rowan ( Sorbus aucuparia L., SA), were analyzed for the total amount and profile of phenolic compounds and for the in vitro antioxidant activity against the DPPH and ABTS radicals (study 1). The seven fruits showed different chemical compositions, which consequently led to different antioxidant potentials. Among the seven fruits initially analyzed, AU, CM, RC, and RU had the highest amount of phenolic compounds and displayed the greatest antioxidant activity in vitro. Extracts from these four fruits were tested as inhibitors of lipid oxidation in raw pork burger patties subjected to refrigerated storage at 2 degrees C for 12 days (study 2). The quantitative measurements of thiobarbituric acid reactive substances (TBA-RS), hexanal content, and color stability were used as indicators of oxidative reactions. The four selected fruits displayed intense antioxidant activity against lipid oxidation, which highlights the potential usage of these fruits as ingredients for the manufacture of healthy meat products. Among them, RC and AU were particularly efficient as their protective effect against lipid oxidation was more intense than that displayed by quercetin (230 mg/kg of burger patty).

붉은 양배추와 마늘종 추출물의 항산화 및 항균활성 평가와 냉장저장 중 돈육패티에 이용

This study was carried out to investigate antioxidative and antimicrobial activities of ethanol extracted garlic stem and red cabbage, and their application to pork patties during refrigerated storage. Total phenolic compounds of ethanol extracted garlic stem and red cabbage were 3.13 g/100 g and 3.99 g/100 g, respectively. 1,1'-diphenyl-2-picryhdrazyl (DPPH) radical scavenging activity of garlic stem extracts increased up to 0.05%. Iron chelating activities of both garlic stem and red cabbage increased up to 0.5%, and red cabbage up to the concentration of 1% had similar iron chelating activity to those of EDTA. Pork patties containing garlic stem had higher Hunter L and b values, (p 0.05). Thiobarbituric acid reactive substances (TBARS) of pork patties with garlic stem were lower than those of the control (p<0.05). In addition, antioxidantive activities of pork patties with red cabbage were higher than those with garlic stem. No differences in microbial contents were observed between the control and treatments. In conclusion, garlic stem and red cabbage extracts might be used as natural antioxidants to be used in the manufacture of functional meat products.

Bioactivity of ellagic acid-, lutein- or sesamol-enriched meat patties assessed using an in vitro digestion and Caco-2 cell model system

Abstract Interest exists in the manufacture of functional meat products whereby synthetic antioxidants are replaced with naturally-sourced compounds. Therefore the aim of this study was to determine the bioactivity of pork and beef patties containing ellagic acid (600 μg/g), lutein (200 μg/g) or sesamol (500 μg/g). Cooked pork and beef patties were subjected to an in vitro digestion procedure and the resultant micelles were added to human intestinal Caco-2 cells. Supplementation with micelles from lutein-enriched pork patties protected (P

Bimodal Method of Determining Fat and Salt Content in Beef Products by Microwave Techniques

A bimodal microwave technique is presented as a rapid analytical method of estimating the fat and salt content of beef products. The dielectric properties of lean meat, fat, salt, and other nonmeat ingredients (dry and aqueous solutions) and meat blends of typical ingredients used in meat product manufacture are all separately investigated. A broadband coaxial probe technique is used to select frequencies of maximum sensitivity. The optimum frequency for fat determination lies between 8 and 20 GHz, and the optimum frequency for salt determination lies below 4 GHz. For example, by using a WR-90 cell, either the real or imaginary part of the complex permittivity can effectively resolve fat content, whereas the imaginary part of the permittivity correlates well with salt content when using a WR-284 cell. The technique is sufficiently robust to ensure that the dielectric effects of other nonmeat ingredients, temperature, and density do not adversely affect this measurement approach.

Bioactivity of Herb-Enriched Beef Patties

Interest exists in the manufacture of meat products with added functional ingredients to enhance consumer health. Because experimental evidence suggests that many herbs and spices, particularly those of the Lamiaceae family such as Salvia officinalis L. (sage) and Origanum vulgare L. (oregano), possess a wide range of biological and pharmacological activities, they represent promising functional ingredients for incorporation into meat and meat products. The present study aimed to determine the bioactivity of cooked beef patties that were enriched with or without sage or oregano extracts (1,200 microg/g). Cooked beef patties were subjected to an in vitro digestion procedure, and the resulting micelles isolated from the digested meats were added to human intestinal Caco-2 cells. The antioxidant potential (ferric reducing antioxidant power [FRAP] value) of enriched beef patties was significantly higher than the FRAP value of non-enriched beef patties, both before and after in vitro digestion. Cell viability significantly increased following treatment with certain concentrations of the micelle fractions from digested sage- or oregano-enriched beef patties. Pretreatment with micelles derived from sage- or oregano-enriched beef patties did not significantly protect against cell injury or DNA damage induced by H(2)O(2). However, micelles derived from digested sage-enriched beef patties (10% vol/vol) significantly increased cellular reduced glutathione (GSH) content. In addition, micelles derived from both sage- and oregano-enriched beef patties (10% vol/vol) significantly protected against H(2)O(2)-induced GSH depletion. Thus, it appears that sage and oregano exhibit some bioactivity within a meat system. Our findings suggest that herbal extracts have potential as possible functional ingredients in meat products.

Effect of Physico-chemical Characteristics of Raw Muscles from Three Iberian × Duroc Genotypes on Dry-cured Meat Products Quality

The effect of raw material characteristics (longissimus dorsi and biceps femoris) on dry-cured loin and ham quality from three different Iberian · Duroc genotypes was studied: GEN1: ♂ Iberian · ♀ Duroc1, GEN2: ♂ Duroc1 · ♀ Iberian; GEN3: ♂ Duroc2 · ♀ Iberian. GEN1 and GEN2 are reciprocal crosses, while the difference between GEN2 and GEN3 is the Duroc sire line. The line Duroc1 (DU1) was selected for the manufacture of dry-cured meat products, whereas the line Duroc2 (DU2) was selected for meat production with low carcass fat. Raw material and dry-cured meat products did not differ between reciprocal crosses (GEN1 vs. GEN2). However, the genotype of the Duroc sire line affected the quality of meat and dry-cured meat products. GEN1 and GEN2 had higher adipogenic nature and higher postmortem pH than GEN3, and as a result, these dry-cured meat products had better instrumental and sensory quality than those from GEN3. By contrast, meat from GEN3 had lower pH, fat content, and oxidative stability which decreased the quality of dry-cured meat products. Therefore, there was a close connection between raw material and dry-cured meat products quality as it was affected by characteristics related to the genotype such as the adipogenic character and meat quality traits associated with pH.

Proteomic Analysis of Cell Envelope fromStaphylococcusxylosusC2a, a Coagulase-Negative Staphylococcus

Staphylococcus xylosus is a saprophytic bacterium commonly found on skin of mammals but also used for its organoleptic properties in manufacturing of fermented meat products. This bacterium is able to form biofilms and to colonize biotic or abiotic surfaces, processes which are mediated, to a certain extent, by cell-envelope proteins. Thus, the present investigation aimed at evaluating and adapting different existing methods for cell-envelope subproteome analyses of the strain S. xylosus C2a. The protocol selected consisted initially of a lysostaphin treatment producing protoplasts and giving a fraction I enriched in cell wall proteins. A second fraction enriched in membrane proteins was then efficiently recovered by a procedure involving delipidation with a mixture of tributyl phosphate, methanol, and acetone and solubilization with a buffer containing ASB14. Proteins were separated using two-dimensional gel electrophoresis (2-DE) and identified using matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS). A total of 168 protein spots was identified corresponding to 90 distinct proteins. To categorize and analyze these proteomic data, a rational bioinformatic approach was carried out on proteins identified within cell envelope of S. xylosus C2a. Thirty-four proteins were predicted as membrane-associated with 91% present, as expected, within fraction II enriched in membrane proteins: 24 proteins were predicted as membranal, 3 as lipoproteins, and 7 as components of membrane protein complex. Eighteen out of 25 (72%) proteins predicted as secreted were indeed identified in fraction I enriched in cell wall proteins: 6 proteins were predicted as secreted via Sec translocon, and the remaining 19 proteins were predicted as secreted via unknown secretion system. Eighty-one percent (25/31) of proteins predicted as cytoplasmic were found in fraction II: 8 were clearly predicted as interacting temporarily with membrane components. By coupling conventional 2-DE and bioinformatic analysis, the approach developed allows fractionating, resolving, and analyzing a significant and important set of cell envelope proteins from a coagulase-negative staphylococcus, that is, S. xylosus C2a.