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1.
《Food Control》2014
Assessment of microbial interactions is crucial for documenting bacterial growth in pure and mixed cultures and their potential for biological applications. Pseudomonas fluorescens (non-plant pathogenic and non-pectinolytic) has been used as a biocontrol microbe for plant pathogens and food-borne bacteria. We determined the growth of Escherichia coli O157:H7 (Ec) and P. fluorescens(Pf) in monocultures and co-cultures in sterile distilled water (SDW), buffered peptone water (BPW) and trypticase soy broth (TSB). The effects of temperatures (5, 10, 15, 20, 25, 35, and 37 °C) and storage time (0, 2, 4, 6, 24, and 48 h) on bacteria populations were assessed. Bacteria counts in monocultures in SDW ranged from 2.14 to 3.03 and 2.54 to 3.31 Log CFU/ml for Ec and Pf; respectively. In BPW, mean bacteria counts (monocultures) ranged from 3.15 to 6.14 and 2.54 to 6.41 Log CFU/ml for Ec and Pf, respectively. Ec populations in co-culture varied with storage temperatures and time. After 48 h, Ec 43894 monocultures in TSB ranged from 2.17 to 8.75 and 2.31 to 8.85 Log CFU/ml at 20 and 35 °C; respectively. In co-cultures with Pf 2-79, Ec 43894 counts ranged from 1.71 to 5.83 (20 °C) and 1.90 to 9.03 Log CFU/ml (35 °C) in TSB. The reductions of Ec by Pf 2-79 varied among strains and generally ranged from 0.20 to 0.90, 0.63 to 1.18, and 0 to 0.56 Log CFU/ml in BPW (10 °C). Substrate availability, storage temperatures, and time significantly (P < 0.05) impacted Ec populations in co-culture. The liquid substrate experiments indicated suppressive conditions of Ec by Pf, however; the reduction of produce contamination by E. coli O157:H7 during transitory temperature abuse conditions such as the transportation of produce from fields needs further investigation. 相似文献
2.
《Food Control》2014
The efficacy of grape seed extract (GE), citric acid (CA) or lactic acid (LA) on the inactivation of Vibrio parahaemolyticus in shucked oysters was studied. The minimum inhibitory concentration (MIC) of GE, CA or LA against V. parahaemolyticus in TSB-1% NaCl was also determined. The shucked oysters were artificially inoculated with V. parahaemolyticus, the inoculated shucked oysters (25 g) were then dipped in solution of GE (0.0, 10.0, 20.0, 50.0, 100, 200, 300 and 500 mg mL−1), CA (0.0, 5.0, 10.0, 15.0, 20.0, 50.0, 100, 200 and 300 mg mL−1) or LA (0.0, 1.0, 5.0, 10.0, 15.0, 20.0, 50.0, 100 and 150 mg mL−1) for 10 min. The population of V. parahaemolyticus in shucked oysters was determined. The MICs of GE, CA or LA against V. parahaemolyticus were 10.0, 5.0 or 1.0 mg mL−1, respectively. A 500, 300 or 150 mg mL−1 GE, CA or LA solutions were needed to reduce the population of V. parahaemolyticus to below the detection level (1.0 log g−1) in shucked oysters. 相似文献
3.
《Food Control》2017
Staphylococcus saprophyticus is a common contaminant in meat and poultry, and causes urinary tract infections after colonization of the gastrointestinal tract, followed by accidental transfer of contaminated feces to the urethra. There is limited information regarding the inactivation kinetics of S. saprophyticus in meat and poultry. When S. saprophyticus was suspended in ground chicken meat (GCM) the thermal processing D10 was 6.26, 0.60 and 0.09 min at 55, 60 and 65 °C, respectively. When S. saprophyticus was inoculated into GCM and subjected to high pressure processing (5 °C, 0–25 min) at 200, 300 or 400 MPa the HPP D10 was 15.5, 9.43, and 3.54 min, respectively. When the S. saprophyticus cocktail was inoculated into GCM and irradiated (5 and −20 °C) the gamma radiation D10 were 0.64 and 0.77 kGy, respectively. When S. saprophyticus was inoculated into chicken purge which was then placed on food contact surfaces including stainless steel, and high density polyethylene and polypropylene and treated with UV-C (0–60 mJ/cm2) the UV-C D10 ranged from 14.9 to 18.5 mJ/cm2. These results indicate the inactivation kinetics for S. saprophyticus are consistent with those for other foodborne pathogens and could be controlled in poultry meat and purge without difficulty. 相似文献
4.
《Food Control》2016
Lactobacillus sakei subsp. sakei 2a is a bacteriocinogenic lactic acid bacteria isolated from a Brazilian meat product, capable to inhibit Listeria monocytogenes in vitro and in foods. In this study, bacteriocin produced by this strain were encapsulated in phosphatidylcholine (FC) and 1,2-dioleoyloxy-3-trimethylammonium-propane (DOTAP) liposomes, separately and in combination, were characterized and evaluated for activity against L. monocytogenes in vitro and in experimentally contaminated UHT goat milk, during storage at 7 °C for 14 days and 30 °C for 24 h. The FC and DOTAP/FC (3:1) nanovesicles containing bacteriocins (12.800 AU mL−1) presented zeta potential of −1.54 and + 38.13 mV, Entrapment Efficiency of 80.0% and 94.1%, and diameter of 91.19 and 81.49 nm, respectively. DOTAP/FC nanovesicle presented excellent stability, and maintained the same physicochemical characteristics over 28 days. Both free and encapsulated bacteriocins controlled L. monocytogenes growth in BHI medium and goat milk stored at 30 °C for at least 8 h, in a similar pattern. After 24 h in BHI medium, bacteriocins encapsulated in FC nanovesicles were more effective (p < 0.05) than free bacteriocins. However, in goat milk, no significant differences (p ≥ 0.05) were observed for the two types of nanovesicles. At 7 °C, both free and encapsulated bacteriocins retarded the L. monocytogenes growth, and after 5 days, counts were 5 log lower than in the controls, both in BHI and in goat milk. Encapsulation of bacteriocin in FC and DOTAP/FC nanovesicles did not affect the antimicrobial activity, but the advantages of their application for control of L. monocytogenes in goat milk based dairy products, when compared to free bacteriocins, remain unclear and more studies are needed. 相似文献
5.
《Food Control》2014
The study established the decimal reduction times at 55 °C (D55 °C values) of acid-adapted and non-adapted Escherichia coli O157:H7, Salmonella enterica, and Listeria monocytogenes in young coconut liquid endosperm. Acid adaptation of the test pathogens was conducted by cultivating cells in a gradually acidifying nutrient broth supplemented with 1% glucose. Results showed that acid adaptation had varying influence on the subsequent thermal resistances of the pathogens. The non-adapted E. coli O157:H7 exhibited the greatest resistance among the tested pathogens with a D55 °C of 23.20 min. Prior adaptation to acidity decreased the D55 °C to 16.16 min. On the other hand, acid adaptation increased the D55 °C values of S. enterica and L. monocytogenes from 8.76 to 10.55 min, and from 7.47 to 18.09 min, respectively. The D55 °C of the non-adapted E. coli O157:H7 was used to establish a pasteurization process schedule with an order of lethality equal to 5-logarithmic (99.999%) reduction. Sensory evaluation revealed that the overall acceptability, color, aroma, coconut flavor, and freshness characteristics of non-pasteurized and pasteurized liquid endosperms were not significantly different (p > 0.05). Moreover, the sensory quality attributes of coconut beverages (80:20 vol/vol endosperm-to-water ratio, soluble solids adjusted to 10 °Brix with sucrose) prepared from both non-pasteurized and pasteurized liquid endosperm samples did not significantly vary. The results obtained from the study may be used in the establishment and validation of thermal process schedules for young coconut liquid endosperm beverages. 相似文献
6.
《Food Control》2017
Tahini (sesame paste) is a low-moisture ready-to-eat food that has been linked to foodborne outbreaks and recalls. The objectives of this study were to investigate the behavior of Staphylococcus aureus in commercial and hydrated tahini at 10, 21 and 37 °C and to inhibit S. aureus in these products by 0.1, 0.3 and 0.5% acetic or citric acid. S. aureus was able to survive in commercial tahini with reductions of 3.3, 1.6 and 0.7 log10 CFU/g at 37, 21 and 10 °C, respectively; while it grew in hydrated tahini with an increase of 3.9, 3.0 and 1.8 log10 CFU/ml at 37, 21 and 10 °C, respectively, by 28d. Citric or acetic acid at ≤ 0.5% reduced S. aureus in commercial tahini by ≤ 2.3 log10 CFU/ml by 28d compared to control at all of the tested temperatures. However, acetic and citric acid were more inhibitory at 37 and 10 °C, respectively. In hydrated tahini, viable S. aureus cells were not detected in the presence of 0.5 or 0.3% acetic acid after 7 and 14d, respectively, at both 21 and 37 °C; and after 14 and 28d, respectively at 10 °C. Acetic acid at 0.1% also reduced S. aureus numbers to undetectable levels after 14 and 28d at 21 and 37 °C, respectively. S. aureus cells were also not detected in the presence of 0.5% citric acid by 21d at all of the tested temperatures, or 0.1 and 0.3% citric acid by 28 and 21d, respectively at 21 °C. Acetic and citric acids could be used in tahini or tahini-based products to reduce the potential risk associated with S. aureus. 相似文献
7.
In this study, we evaluated the inactivation of foodborne pathogens inoculated on chicken breasts by UV-C treatment. Chicken breasts were inoculated with Campylobacter jejuni, Listeria monocytogenes, and Salmonella enterica serovar Typhimurium at 6–7 log CFU/g. The inoculated chicken breasts were then irradiated with UV-C light of dose 0, 0.5, 1, 3, and 5 kJ/m2. Microbiological data indicated that the populations of the foodborne pathogens decreased significantly (p < 0.05) with increasing UV-C irradiation. In particular, UV-C irradiation at 5 kJ/m2 reduced the initial populations of C. jejuni, L. monocytogenes, and S. typhimurium by 1.26, 1.29, and 1.19 log CFU/g, respectively. After UV-C irradiation, the samples were individually packed using polyethylene terephthalate containers and stored at 4 ± 1 °C for 6 d. The pH of the control increased more than the samples irradiated at 0.5, 1, 3, and 5 kJ/m2, while TBARS values increased during storage regardless of UV-C irradiation. UV-C irradiation caused negligible changes in Hunter L, a, and b values. These results suggest that UV-C irradiation can be useful in improving the microbial safety of chicken breasts during storage, without impairing quality. 相似文献
8.
《Food Control》2014
Forty-two mahi-mahi fillets and 17 dried products sold in retail markets in Taiwan were tested for histamine and histamine-forming bacteria. The levels of pH, salt content, water content, Aw, TVBN, APC, TC and Escherichia coli in mahi-mahi fillet samples ranged from 5.6 to 6.5, 0.05 to 2.44%, 70.9 to 82.8%, 0.95 to 0.99, 5.9 to 23.5 mg/100 g, 3.1 to 7.0 log CFU/g, <3 to 1650 MPN/g and <3 to 45 MPN/g, respectively. The levels of pH, salt content, water content, Aw, TVBN, APC, TC and E. coli in dried mahi-mahi samples ranged from 5.7 to 6.4, 0.63 to 20.13%, 7.1 to 42.9%, 0.51 to 0.85, 21.4 to 133.9 mg/100 g, 3.6 to 8.7 log CFU/g, <3 to 5900 MPN/g and <3 to 2500 MPN/g, respectively. The average content of various biogenic amines in fillets samples was less than 0.3 mg/100 g. Four of the 17 dried samples (23.4%) had histamine levels greater than the FDA guideline of 5 mg/100 g for scombroid fish and/or product with one of them containing 68.15 mg/100 g of histamine, which is greater than the 50 mg/100 g hazard action level. Eight histamine-producing bacterial isolates, capable of producing 12.6 ppm–562 ppm of histamine in trypticase soy broth supplemented with 1.0% l-histidine (TSBH), were identified as Raoultella ornithinolytica (three isolates), Pantoea agglomerans (two isolates), Proteus vulgaris (two isolates) and Enterobacter amnigenus (one isolate), by 16S rDNA sequencing with PCR amplification. 相似文献
9.
《Food Control》2014
Aspergillus carbonarius is the major ochratoxin A (OTA)-producing fungus that contaminates wine grapes. To investigate the effect of the initial amount of A. carbonarius on winemaking and ochratoxin A contamination, different conidial concentrations of A. carbonarius were manually added to the grape musts before fermentation. Sampling was carried out at different stages in alcoholic fermentation, including crushing, maceration, pressing and alcoholic fermentation. The levels of alcohols, soluble solids, and reducing sugars in the musts were analyzed before and during the whole procedure of alcoholic fermentation. Aspergillus spp. and other fungal contaminants increased rapidly after crushing, however most died at 48 h. OTA levels in the musts increased during the first 8–48 h and then decreased sharply in A. carbonarius inoculants (1 × 104 to 1 × 106 spores/g) in a spore concentration-dependent manner. Most OTA was retained in the pomaces fraction after the pressing operation. High amounts of A. carbonarius did not significantly affect yeast growth, sugar use, and alcoholic production during fermentation. In conclusion, high levels of contamination with A. carbonarius in the grape musts did not inhibit alcoholic fermentation, but caused high OTA residues in the wine produced. 相似文献
10.
《Food Control》2017
Reduced moisture enhances resistance of Salmonella and subsequently reduces the antimicrobial efficacy of thermal treatment. Alternative and supplementary non-thermal intervention methods are urgently needed. In this study, Cinnamonum cassia oil was tested for its antimicrobial effect against outbreak strains Salmonella Enteritidis PT30 and S. Tennessee K4643. Minimal inhibitory concentration and minimal bactericidal concentration for both strains were 0.05% (v/v) and 0.1% (v/v), respectively. Death curves showed that including 0.1% and 0.15% (v/v) C. cassia oil resulted in ∼7 Log reduction of bacteria within 2 h and 1 h, respectively. However, the antimicrobial efficacy of C. cassia oil was reduced when S. Enteritidis PT30 existed in low moisture condition. When S. Enteritidis PT30 was established on almonds/paper discs, 0.4% C. cassia oil resulted in ∼1.7 Log10 CFU/almond or 3.2 Log10 CFU/disc reduction within 2 h at room temperature, respectively. S. Enteritidis PT30 established on both almonds and paper discs were very stable, there was only a 0.80 Log10 CFU/almond and 1.20 Log10 CFU/disc reduction during 9-week and 7-week storage at room temperature, respectively. C. cassia oil intervention increased S. Enteritidis PT30 reduction on both almonds and paper discs during storage with more reduction on paper discs. 0.4% C. cassia oil treatment reduced S. Enteritidis PT30 on paper disc to undetectable level within 4 weeks, but only led to 2 Log10 CFU reduction on almonds, indicating a protection effect from the almond matrix or almond surface components. Additionally, S. Enteritidis PT30 established on paper disc coated with almond surface components exhibited higher resistance to desiccation and C. cassia oil treatment, further demonstrating the protection role of food matrix. In conclusion, C. cassia oil is effective against S. Enteritidis PT30 and S. Tennessee K4643, but its antimicrobial efficacy against the tested Salmonella was compromised by low moisture environment and food matrix. 相似文献
11.
《Food Control》2018
Numerous studies examined the antimicrobial effects of spice and herb extracts, whereas little is known about the effects of dry condiments on the survival of microorganisms. This study investigated the impact of dried condiments on the survival of Bacillus cereus and B. thuringiensis spores as well as Staphylococcus aureus cells. In addition, the survival variability between different strains was evaluated. Condiments (allspice, basil, cinnamon, nutmeg, oregano, paprika, parsley and pepper) were artificially contaminated by a dry spiking method using sand as carrier matrix and as control. The results show that counts of B. cereus and B. thuringiensis spores (initial spore count 5.6 ± 0.2 log10 cfu/g and 6.7 ± 0.1 log10 cfu/g, respectively) did not decline significantly in all condiments over a period of 50 weeks. In contrast, in some of the spiked test materials, cell counts of S. aureus (initial cell count 8.1 ± 0.5 log10 cfu/g) were reduced below the detection limit of 10 cfu/g within 10 weeks of storage. D values for S. aureus ranged between 5 and 31 days depending on the strain, condiment and initial contamination level. In conclusion, dried condiments may not affect the survival of spores but can significantly affect the survival of non-spore forming bacteria. As strain variability can occur, tenacity studies should be conducted including a variety of strains. 相似文献
12.
1,1?-Diamino-4,4?,5,5?-tetranitro-2,2?-biimidazole (DATNBI) was synthesized, by employing one-pot facile method, from 4,4?,5,5?-tetranitro-2,2?-biimidazole. The crystal structure was determined by X-ray diffraction for the first time. DATNBI crystallized in monoclinic system P21/c, with a crystal density of 1.934 g cm?3 at 293(2) K and 2.019 g cm?3 at 130(2) K, respectively. Its crystal parameters at 293 K are a = 4.8833(15) Å, b = 6.960(2) Å, c = 6.928(4) Å, α = γ = 90°, β = 93.418(6)°, V = 591.1(3) ?3, Z = 2, μ = 0.178 mm?1, and F(000) = 348. The thermal stability and non-isothermal kinetics of DATNBI were studied by differential scanning calorimeter (DSC) with heating rates of 5, 10, 15, and 20 K min?1. The apparent activation energy (Ea) at the first decomposition peak calculated by Kissinger, Ozawa, and Starink equations were 85.50, 89.67, and 86.10 kJ mol?1, respectively. For the second peak, these were 116.49, 119.82, and 117.45 kJ mol?1, respectively, with individual pre-exponential factors lnA = 18.40 s?1 and lnA = 25.11 s?1. The thermogravimetry-Fourier transform infrared spectroscopy (TG-FTIR) analysis of thermal decomposition products reveals that the main decomposition gas products are H2O, N2O, CO2, and NO2. Based on the new crystalline densities, the detonation velocity and pressure predicted by EXPLO5 are 9062 m s?1 and 36.4 GPa, respectively. 相似文献
13.
The composition and distribution of saturated hydrocarbons (alkanes, steranes, and terpanes) of oils from the Ulyanovsk oblast
of the Volga-Urals oil-and-gas basin were studied. Wax fractions were isolated from crude oils, and C48-C52 high-molecular-mass n-alkanes, C35-C52 alkylcyclopentanes, and C24-C42 2- and 3-monomethylalkanes were identified in these fractions. Based on the data on the composition of C10-C36
n-alkanes, C19-C35 terpanes, C21-C30 steranes, and C40+ alkanes, it was shown that the oils in question were generated by marine organic matter in carbonate sediments. Oil from
the Novolabitovskoe field (1981–1992 m) substantially differs for the other oils in terpane and sterane compositions. These
differences are supposedly due to another source of organic matter. 相似文献
14.
Abstract The effect of microbial count of Pseudomonas aeruginosa bacteria amended with 20 g of nitrogen-phosphorous-potassium (NPK) fertilizer (15:15:15) on the biodegradation of crude oil-contaminated water was studied. Four samples, S 1, S 2, S 3, and S 4, with equal crude oil pollution load were inoculated with, 1 × 105 cfu, 2 × 105 cfu, 4 × 105 cfu and 8 × 105 cfu of P. aeruginosa respectively, and 20 g of NPK (15:15:15) fertilizer. The control sample, Sc, had only 8 × 105 cfu P. aeruginosa and no fertilizer. Parameters such as oil and grease content, pH, BOD, COD, and turbidity were monitored over a nine-week period. At the end of the biodegradation period, a high percentage of oil and grease content was removed. The value reduced from 185.0 to 41.50 mg/L, 24.6 mg/L, 20.5 mg/L, 13.2 mg/L, 10.9 mg/L for S c , S 1, S 2, S 3, and S 4 respectively. There was also a drop in BOD, COD, turbidity, and pH of the samples under consideration. The S 4 sample had the highest reduction in both BOD and COD values. The initial value dropped from 82.0 to 27.5 mg/L and 158.4 to 64.8 mg/L for the BOD and COD, respectively. These values obtained fall within the Federal Environmental Protection Agency (FEPA) limits. The oil and grease content for S 4 sample was also reduced from 185 mg/L to 9.95 mg/L, while the pH value for this same sample, S 4, was 6.60 after the nine-week period of investigation. 相似文献
15.
《Food Control》2014
This study established the inactivation kinetic parameters of some pathogenic bacteria including Escherichia coli O157:H7, Salmonella enterica serotypes, and Listeria monocytogenes; and spoilage yeasts namely, Debaryomyces hansenii, Clavispora lusitaniae, Torulaspora delbrueckii, Pichia fermentans, and Saccharomyces cerevisiae in orange juice subjected to multi-frequency Dynashock power ultrasound treatment. All test organisms exhibited a biphasic inactivation behavior with a sigmoidal inactivation curve consisted of an initial inactivation lag, followed by logarithmic linear inactivation. Injury accumulation in the inactivation lag phase was established in acid-adapted bacteria. The time necessary to reduce initial inoculated populations by 5 log cycles (99.999%), T5D values, significantly increased with acid adaptation. The T5D of E. coli, S. enterica, and L. monocytogenes increased from 37.64, 36.87, and 34.59 respectively; to 54.72, 40.38, and 37.83 min respectively after acid exposure. Temperature increase due to sensible heat propagation during ultrasound treatment decreased the resistance of the test bacteria. The cocktail of E. coli O157:H7 had significantly greater resistance towards ultrasound treatment (T5D = 54.72 min) than any of the individual strain (T5D = 41.48–47.48 min) in the mix. Similar results were found in the composited (T5D = 60.02 min) and individual species (T5D = 20.31–59.04 min). The results established in this work provide baseline information on microbial behavior in multi-frequency ultrasound-treated orange juice for establishment of pasteurization process schedules. 相似文献
16.
《Food Control》2014
For the purpose of preparing lactic acid bacteria (LAB) carrier food, the solid-state fermentation of whole soybean was performed using Bifidobacterium animalis 937, Lactobacillus casei Zhang and Lactobacillus plantarum P-8 mixed with Bacillus subtilis natto, respectively. The physicochemical properties, the amino nitrogen content and peptide molecular weight distribution of the fermented whole soybean products were examined during this process. After 48 h of fermentation, the viable counts of the three samples were 1.41 × 108 CFU/g (B. animalis 937), 1.74 × 1010 CFU/g (L. casei Zhang) and 2.19 × 1010 CFU/g (L. plantarum P-8), with the pH declined rapidly from 6.32 to 5.78, 5.60 and 5.44 at the early stage of the fermentation and increased to 6.71, 6.47 and 6.60 at the later stage of the fermentation. The fermentation caused a sharply increase in the content of the free amino nitrogen from 99.7 μmol/g to 301.9 μmol/g, 390.1 μmol/g and 529.1 μmol/g in the solid fermented soybean products, due to the multiplication of microorganism and the effect of enzyme system. Furthermore, the levels of soybean peptide with molecular weight less than 1000 Da increased 30.7%, 71.2% and 81.3% relative to that of the control group at 48 h. The result of the present work implied that whole soybean fermented by LAB can provide the different probiotics for the host, and there is potential to develope nutritious fermented soybean products. 相似文献
17.
采用N2/H2程序升温还原法制备了非负载型氮化钼(Mo2N)和氮化镍钼(Ni2Mo3N)催化剂,并以Al2O3为载体制备了负载型氮化钼(Mo2N/Al2O3)和氮化镍钼(Ni2Mo3N/Al2O3)催化剂。采用XRD、BET、H2-TPR和NH3-TPD等方法对制备的氮化物催化剂的性质进行了研究,并分别以含2%(质量分数,下同)噻吩和10%四氢萘的环己烷溶液为含硫、含芳烃的柴油模型化合物,考察了制备的负载型氮化物的加氢脱硫(HDS)及加氢脱芳烃(HAD)性能。结果表明,以金属氧化物为前驱物,采用N2/H2程序升温还原法制得的氮化钼为Mo2N(γ型)、氮化镍钼为Ni2Mo3N;经钝化处理后,氮化物表面形成了金属氧化物保护层,其中Mo2N/Al2O3和Ni2Mo3N/Al2O3表面氧化层的还原温度分别为350和300℃。Mo2N/Al2O3和Ni2Mo3N/Al2O3催化剂的表面酸性以弱酸为主;二者均表现出较好的HDS性能,但Mo2N/Al2O3的HDA性能很差,而Ni2Mo3N/Al2O3的HDA性能较Mo2N/Al2O3有一定程度的提高,说明镍钼共存有利于提高金属组分的分散性及催化剂的加氢饱和性能。 相似文献
18.
Wax emulsions were prepared by using paraffin wax and oxidized wax as raw materials, compound Wb-L as emulsifier, and C5 petroleum resin as stabilizer. Its performance was studied. The results showed that when M C5 petroleum resin r/M wax and oxidized wax = 0.20, M emulsifier/M wax and oxidized wax = 0.50, M water/M wax and oxidized wax = 2.50, emulsifying time was 30 min, emulsifying temperature was 90–95°C, and stirring speed was 1,100 r/min, wax emulsions with good stability, dispersibility, and monodisperse particle size were obtained, giving a preservative solution in pencil board production. 相似文献
19.
《Food Control》2016
The presence of tryptamine, phenylethylamine, putrescine, cadaverine, histamine, tyramine, spermidine and spermine was determined for the first time in beers commercialized in Chilean market. Dansylated amines were separated on a Zorbax-XDB C18 column using a binary mobile phase composed of acetonitrile and 20 mmol L−1 ammonium formate, pH 5.5. Chromatographic conditions were optimized using an experimental design, and validation was carried out following ICH recommendations. Calibration data fitted a linear regression model with R2 > 0.996. Repeatability (n = 6) and intermediate precision (n = 3) in matrix showed RSD values lower than 5.00% and 5.21%, respectively. Recoveries at three different concentrations ranged from 75.50 to 96.48%. The proposed method was applied to determine the biogenic amines content in 101 beer samples produced by macro- (n = 65) and microbreweries (n = 36) using low (n = 63) and high fermentations (n = 38). Biogenic amines content in beer samples ranged from 0.53 to 85.04 mg L−1, from which beers produced by microbreweries (19.13 ± 16.92 mg L−1) showed a significant higher biogenic amines content (P = 0.0021) than beers produced by macrobreweries (9.65 ± 4.50 mg L−1). Putrescine was the principal biogenic amine found in all kind of beers regardless origin, and the type of fermentation and brewery. Only 2 samples presented relevant levels of histamine and tyramine, but both below the limits reported by the European Food Safety Authority (EFSA). Thus, it can be concluded that beers commercialized in Chile are not a serious toxicological risk (e.g. hypertensive crisis) regarding the type and content of biogenic amines. 相似文献
20.
《Food Control》2014
Shiga toxin-producing Escherichia coli (STEC) have caused numerous foodborne outbreaks. Compared with the most well-known STEC E. coli O157:H7, importance of non-O157 STEC has been underestimated and they have gained far less attention till increasing outbreaks recently. Using natural plant materials as antimicrobial agents is a heated area. Therefore in this study, Cinnamomum cassia, a widely used spice in cuisine, was tested for its antibacterial efficacy on CDC “top six” non-O157 STECs including O26, O45, O103, O111, O121, O145. Gas chromatography-mass spectrometry analysis showed that the major component of C. cassia oil was cinnamaldehyde (59.96%). The disk diffusion assay indicated that 20 μL 4% (v/v) C. cassia oil per disk resulted in inhibition zones of 15.0 mm, 18.5 mm, 15.7 mm, 19.3 mm, 18.8 mm, and 25.3 mm for O26:H11, O45:NM, O103:H2, O111:H2, O121:H19, and O145:NT, respectively. Minimum inhibitory concentration for all tested non-O157 STECs were 0.025% (v/v). Minimum bactericidal concentration was strain dependent, which was 0.05% (v/v) for O26:H11, O121:H19, O145:NT, while 0.1% (v/v) for O45:NM, O103:H2 and O111:H2. Growth kinetics showed that at the low inoculation of approximate 2.5 × 105 CFU/mL, C. cassia oil at the concentration of 0.01875% (v/v) completely inhibited the growth of O26:H11 and O145:NT for at least 24 h, and increased the duration of lag phase of O45:NM, O103:H2, O111:H2, O121:H19 by18, 12, 6, and 16 h, respectively. Including 0.025% (v/v) C. cassia oil completely inhibited the growth of all tested non-O157 STECs for at least 24 h. At high inoculation of 5 × 106 CFU/mL, inhibition effect of C. cassia oil decreased. Death curve showed that including as low as 0.05% (v/v) C. cassia oil could kill non-O157 STECs. 0.1% (v/v) C. cassia oil showed bactericidal effects on all tested non-O157 STECs within 15 min. C. cassia oil at the concentration of 0.15% (v/v) killed all O26:H11, O121:H19 and O145:NT within 30 min, while O45:NM, O103:H2 and O111:H2 at 120, 60, and 60 min, respectively. In conclusion, C. cassia oil can effectively inhibit the growth of non-O157 STECs at concentration as low as 0.025% (v/v). Our data suggest that C. cassia oil has the potential to be used as a natural antibacterial agent in food industry. 相似文献