纳豆芽孢杆菌（Bacillus natto）发酵鱿鱼碎肉的工艺优化

为进一步提高鱿鱼碎肉的利用价值,本实验以鱿鱼碎肉作为纳豆芽孢杆菌发酵基质,研究料液比、葡萄糖添加量、发酵pH值、发酵时间和发酵温度对鱿鱼碎肉发酵效果的影响。在以单因素试验确定发酵时间72 h和发酵温度37 ℃的条件后,再对料液比、发酵pH值和加糖量进行三因素三水平的Box-Behnken响应面试验分析,以发酵液的氨基态氮含量为响应值,得到纳豆芽孢杆菌发酵鱿鱼碎肉最佳条件为：料液比1∶1.2（m/V）、发酵pH 8.8和加糖量3.13%。在最优发酵条件下,鱿鱼碎肉发酵液的氨基态氮实际含量达到2.457 mg/mL。氨基酸分析结果显示鱿鱼碎肉发酵液富含具有鲜味和甜味特征的谷氨酸（84.141 mg/g）、天冬氨酸（49.480 mg/g）和甘氨酸（49.425 mg/g）,达到氨基酸总量的39.05%。必需氨基酸总量为149.320 mg/g,占氨基酸总量的31.86%。Sephadex G25凝胶过滤层析显示鱿鱼碎肉纳豆芽孢杆菌发酵液由多肽、小肽及游离氨基酸组成。     

Color and Quality of Mackerel Surimi as Affected by Alkaline Washing and Ozonation

Washing with alkaline phosphate or bicarbonate buffers (>pH 8.0) did not remove the pigments from minced mackerel. Thirty min ozonation in citrate buffer (pH 3.0) increased the whiteness (51.7 to 60.1) and L value (53.9 to 62.6), and decreased myoglobin (47.8 to 12.2 mg/100g) and total pigments (78.5 to 15.5 mg/100g). However, the deformation of surimi decreased from 0.90 cm to 0.45 cm, even though there was no change in breaking force. In comparison with untreated sample, addition of 0.10% NaHSO₃, 0.15% cysteine or 0.20% ascorbic acid during grinding resulted in substantial recovery of the deformation and breaking force of ozonated surimi.     

Parameters affecting the isolation of collagen from squid (Illex argentinus) skins

The solubility of collagen from squid (Illex argentinus) skin in salt solutions and the efficiency of removal of skin chromatophores were determined. Homogenization of minced squid skin in 5–15% NaCl solution at 0°C solubilized 35–24% of total amount of crude protein and caused 2–5% loss of collagen but was not effective in removing pigments from the skin. The treatment of whole squid skins in 5–15% NaCl solutions at room temperature led to separation of the chromatophores, but the loss of soluble collagen was 57–16%. Collagen, soluble in dilute acid solutions was isolated from squid skins by 24 h soaking in 10% NaCl solution at room temperature, washing with water and bleaching for 48 h in 1% H₂O₂ in 0.01 M NaOH. The yield of collagen was 53%. It could be increased to 90% by using NaOH solution at pH 11.5 instead of 10% NaCl but the isolate was less soluble in dilute acid and the viscosity of 0.5% dispersion of collagen was four times lower. The rancid off-odour could be prevented by adding 0.5% of a non-ionic detergent to all solution used in the procedure. ©     

Distribution and removal of added mercury in milk.

Distribution patterns of added mercury in raw whole milk after equilibration for 30 min and 2 h at 37 C showed a distribution among acid casein, whey proteins, fat globule membrane, and soluble fat globule membrane of 33, 28, 16, and 2%. On the basis of protein content, the fat globule membrane had the highest amount of mercury. Mercury added to milk as mercuric chloride was removed by treatment with thiolated aminoethyl celluloses and reduced human hair. In a 5 min treatment, 70, 43, and 41% of the mercury was removed by thiosuccinylated aminoethyl cellulose, thionitrocarboxyphenylated aminoethyl cellulose, and reduced human hair, respectively, from whole milk initially containing 1 ppm mercury and equilibrated for 2 h at 37 C prior to treatment. After treatment for 60 min, 82, 52, and 64% of the mercury was removed by thiosuccinilated aminoethyl cellulose, thionitrocarboxyphenylated aminoethyl cellulose, and reduced hair, respectively. However, increasing incubation temperature and time prior to treatment decreased the removal efficiencies. Thiosuccinilated aminoethyl cellulose and reduced human hair showed increasing efficiency directly with pH, while thionitrocarboxyphenylated aminoethyl cellulose showed the opposite effect and had higher affinity for mercury at pH 5.5 than at pH 7.5. Moreover, the rate of removal of mercury at 4 C compared to 37 C was much slower. The removal of mercury from soluble casein and soluble whey proteins was more efficient than from micellar casein. Protein, lactose content, and pH of milk were not changed by the polymer treatments.     

不同保鲜剂对4 ℃冷藏鲶鱼鱼糜保鲜效果的影响

从几种天然保鲜剂中选取一种能够脱除鲶鱼鱼糜的土腥味并且抑制其鲜味降解的保鲜剂,以提高鲶鱼鱼糜
的经济价值和食用安全性。在5 份等质量鲶鱼碎肉中分别添加质量分数为0.5%血浆蛋白、0.5%鱼骨肽、10%壳聚糖
＋0.3%茶多酚复合剂、12.5%乳清蛋白、1%干酵母＋0.3%葡萄糖复合剂5 种天然保鲜剂,托盘包装并于4 ℃冷藏。
选取冷藏过程中pH值变化的3 个关键点（起始点、极限pH值点和pH＞7.0的鱼肉腐败点）,在这3 个关键点测定鱼
糜的硫代巴比妥酸反应物（thiobarbituric acid-reactive substances,TBARS）值、挥发性盐基氮（total volatile basic
nitrogen,TVB-N）值、微生物等指标的变化情况。结果发现,鲶鱼鱼糜中添加0.5%鱼骨肽可以延长鲶鱼鱼糜达到极
限pH值的时间,且TVB-N值、TBARS值及细菌总数均低于其他组。0.5%鱼骨肽对鲶鱼鱼糜的保鲜效果最好。     

白芨多糖胶的酶法精制工艺条件研究

进行白芨多糖的酶法精制工艺研究,初步考察5 种蛋白酶对白芨多糖的精制效果,并选择木瓜蛋白酶进一步研究,考察加酶量、pH 值、温度和酶解时间对白芨多糖纯度和蛋白残余率的影响,确定了适宜的酶解条件：加酶量8～10mg/g 底物,pH7.0～7.5,温度45～50℃,酶解时间120～150min。精制白芨多糖中葡甘聚糖最高含量可达97.0%,蛋白含量由粗多糖的0.91% 下降到0.32%。实验同时进行了酶法随程处理研究,获得的多糖纯度达92.0%。该法提供了一种更为简单的白芨多糖提取和精制工艺。     

ROLE OF INITIAL MUSCLE pH ON THE SOLUBILITY OF FISH MUSCLE PROTEINS IN WATER

The solubility of the myofibrillar and cytoskeletal proteins in water was determined for the muscle tissue often species offish. The flesh of six white-muscled fish had pH's at the time of processing above pH 6.6 and greater than 80% of their myofibrillar/cytoskeletal proteins were soluble in water. The flesh of three pelagic species and a shark had pH values when processed below 6.6 and the water solubility of their myofibrillar and cytoskeletal proteins was less than 40%. When the washed minced muscle of one of the white-fleshed species, cod, was exposed to low pH, the solubility of its myofibrillar and cytoskeletal proteins decreased substantially. The water solubility of the cod myofibrillar and cytoskeletal proteins could be reestablished by washing the acid-treated cod flesh with neutral salt solutions. It is suggested that pH values below 6.6 modify certain proteins which prevent the water-extractability of the rest of the myofibrillar and cytoskeletal proteins from being expressed.     

Concentration and Exposure Assessment of Mercury in Commercial Fish and Other Seafood Marketed in Oman

The results of this study present analytical data of the mercury levels in several fish and shellfish species to create awareness among individuals of the risks associated with consuming fish contaminated with mercury. Mercury concentrations varied from a mean of 0.02 mg/kg in Indian mackerel to 0.19 mg/kg in shark in both fresh and frozen fish, from 0.02 mg/kg in sardines to 0.18 mg/kg in skipjack tuna in canned fish, and from 0.02 mg/kg in Indian mackerel to 0.79 mg/kg in shark in dried fish. Shellfish contained a slightly higher amount of mercury than fresh or frozen fish with a mean of 0.09 mg/kg. Trophic position, followed by habitat, was the most important factors for variability in mercury concentrations in fish and shellfish. The maximum safe weekly intake (MSWI) values of mercury were significantly higher for herbivores than for carnivores. The MSWI value for total mercury in the case of consuming most (72%) fish species was more than 5 kg; however, the MSWI value was never more than 5 kg in most (66%) shellfish species. Risks were identified upon consumption of 120 g of dried shark when exceeding the provisional tolerable weekly intake threshold (1.6 μg/kg) for methylmercury. Therefore, fish‐eating populations should reduce the quantity of dried shark to efficiently diminish the exposure to mercury.     

Effectiveness of Cross-Flow Microfiltration for Removal of Microorganisms Associated with Unpasteurized Liquid Egg White from Process Plant

ABSTRACT:  Thermal preservation is used by the egg industry to ensure the microbiological safety of liquid egg white (LEW); however, it does not eliminate all microorganisms and impairs some of the delicate functional properties of LEW. In this study, a pilot-scale cross-flow microfiltration (MF) process was designed to remove the natural microflora present in commercial LEW, obtained from a local egg-breaking plant, while maintaining the nutritional and functional properties of the LEW. LEW, containing approximately 10^{6 ± 1.7} colony forming units (CFU) per milliliter of total aerobic bacteria, was microfiltered using a ceramic membrane with a nominal pore size of 1.4 μm, at a cross-flow velocity of 6 m/s. To facilitate MF, LEW was screened, homogenized, and then diluted (1 : 2, w/w) with distilled water containing 0.5% sodium chloride. Homogenized LEW was found to have a threefold lower viscosity than unhomogenized LEW. Influence of MF temperature (25 and 40 °C) and pH (6 and 9) on permeate flux, transmission of egg white nutrients across the membrane, and microbial removal efficiency were evaluated. The pH had a significantly greater influence on permeate flux than temperature. Permeate flux increased by almost 148% when pH of LEW was adjusted from pH 9 to pH 6 at 40 °C. Influence of temperature on permeate flux, at a constant pH, however, was found to be inconclusive. Microbial removal efficiency was at least 5 log₁₀ CFU/mL. Total protein and SDS-PAGE analysis indicated that this MF process did not alter the protein composition of the permeate, compared to that of the feed LEW, and that the foaming properties of LEW were retained in the postfiltered samples.     

Aspects of the epidemiology of Yersinia enterocolitica: a review

A review of works concerning different aspects of the epidemiology of human pathogenic Yersinia enterocolitica biogroup IV/serogroup O:3 (Y. enterocolitica O:3) is given. To investigate the epidemiology of Y. enterocolitica O:3 in Danish herds of pigs, tonsil swabs from 2218 freshly slaughtered pigs originating from 99 herds were examined. The organism was isolated from 25% of the pigs and from 82% of the herds. No herd management factor could be associated with the presence of the organism. The effect of slaughtering technique on surface contamination with Y. enterocolitica O:3 was investigated. 1256 pigs were slaughtered by different evisceration techniques. When a mechanical bung cutter was used instead of the traditional, manual evisceration the contamination was reduced markedly, especially when the rectum and anus were enclosed in a plastic bag prior to the removal of the gut. It was possible to reduce the rate of the surface contamination from 26% on the medial hind limb and 13% on the split sternum and surroundings to about 2% for both sampling sites. An investigation of the presence of Y. enterocolitica O:3 in meat and meat products in retail butcher's shops was performed. The organism was detected in 10 of 33 samples of minced pork and in three of 24 samples of minced beef, but in none of 32 samples of sliced vacuum packed, low to medium salt meat products. The positive minced beef samples were collected at butcher's shops from which positive samples of minced pork were found as well. It is concluded that Y. enterocolitica O:3 is common in pork with a risk of cross-contamination to other products for example ready-to-eat meat products that might be a source of human infection.     

Novel mercury control technology for solid waste incineration: sodium tetrasulfide (STS) as mercury capturing agent

Traditional pollution control technologies are able to capture oxidized forms of mercury to some extent; however, they show low efficiency for the control of elemental mercury emissions. This study developed a novel mercury removal technology: injection of sodium tetrasulfide (Na2S4) dissolved in the sodium hydroxide (NaOH) solution in the spray-dryer system. The effects of flue gas temperature and Na2S4 level in flue gas on the mercury removal efficiency were investigated. Na2S4 was decomposed into Na2S (S2-) and elemental S (S0), which reacted with HgCl2 and elemental Hg (Hg0), and HgS was then formed. Under the optimized operation parameters, this technology can simultaneously remove over 88% of HgCl2 and more than 90% of Hg0 from a flue gas stream containing about 400 microg m(-3) Hg0 and 1200 microg m(-3) HgCl2. The increased flue gas temperature (>170 degrees C) and the decreased Na2S4-to-Hg mass ratio (S-Hg-R) (<2.0) had negative effects on the reactions of gaseous mercury (HgCl2 + Hg0) with ionic sulfur (S2-) and S0. All the experiments were conducted in a full scale hospital-waste incinerator with a capability of 20 tons per day (TPD).     

Effects of washing pre-treatment on mercury concentration in fish tissue

The objective of this study was to examine the effect of washing pre-treatment on mercury concentration in fish fillet. Response surface methodology was used to investigate the influence of three variables, pH (1–6.5), NaCl (0–1% w/v) and exposure time (5–30 min) by using a three-factor central composite design. The aim was to obtain the best possible combination of these variables in order to reduce mercury in fish fillet. The experimental data were adequately fitted into a second-order polynomial model with multiple regression coefficients (R ²) of 0.961. The results indicated that the reduction of mercury in fish flesh significantly depends on the pH of the solution used. The overall optimal condition resulting in the maximum mercury reduction in fish fillet was obtained at a combined level pH of 2.79, NaCl of 0.5% and exposure time of 13.5 min. The optimized protocol produced a solution that can reduce mercury from raw fish fillet up to 81%.     

An electrochemical system for removing and recovering elemental mercury from a gas stream

The impending EPA regulations on the control of mercury emissions from the flue stacks of coal-burning electric utilities has resulted in the development of numerous advanced mercury control technologies such as sorbent injection and in-situ mercury oxidation. Although these technologies can effectively remove mercury from a flue stack they share, along with many other technologies, the common shortcoming of intermedia pollution transfer i.e. the traffic of mercury from the air phase to the solid phase and the subsequent generation of residue for landfill. This work addresses the need for an integrated system of mercury removal and recovery from flue stack gases and from the environment. The research explored the capture of elemental mercury from the gas phase at ambient temperature on an electrically conductive porous sorbent. The mercury loaded sorbent was regenerated at the anode in an electrochemical cell and the oxidized mercury recovered at the cathode as solid elemental mercury. Activated carbon cloth was selected as the most suitable sorbent as it had the highest mercury adsorption capacity of the sorbents tested and was electrically conductive. Direct and indirect electro-oxidation were shown to remove 95% and 100%, respectively, of the elemental mercury from the carbon cloth. After regeneration the carbon cloth was reused without any loss in mercury adsorption capacity. More than 99% of the mercury stripped from the cloth during regeneration was recovered at the cathode.     

Modeling dependence of growth inhibition of Salmonella Typhimurium and Listeria monocytogenes by oregano or thyme essential oils on the chemical composition of minced pork

The aim of this study was to compare the antimicrobial effect of selected essential oils (EOs) at concentration of 1% in minced pork from five different meat cuts (loin, ham, shoulder, neck, and belly) and to assess the influence of the chemical parameters of meat on EO efficiency, determined by the decrease of pathogens in comparison to a control in samples after storage at 3°C/7 d in a vacuum. The inhibition was significant (p < .05) only in minced pork from meat cuts with a fat content lower than 5% (leg, loin and shoulder). Salmonella enterica serovar Typhimurium was more sensitive than Listeria monocytogenes and oregano was more effective than thyme (p < .001). The inhibition of S. Typhimurium depended mainly on the fat content (logarithmic dependence) and to a lesser degree on the pH, whereas pH was not found to be a significant predictor in the case of L. monocytogenes. The results of this study show that only lean minced meat (with a fat content max. 5%) is a suitable matrix for pathogen control by EOs.     

Remediation of elemental mercury using in situ thermal desorption (ISTD)

In situ thermal desorption (ISTD) is a soil heating method that simultaneously applies heat and vacuum to the subsurface at temperatures up to 600 degrees C. As the soil is heated, the vapor pressure of the contaminant increases allowing mass transfer to the gas phase and extraction from the soil using vacuum wells. The overall goal of this research is to assess the feasibility of using ISTD to remove elemental mercury from soils. The initial phase of research included design of a laboratory soil column apparatus and preliminary soil column experiments with surrogate nonaqueous phase liquids (perfluorocarbons) to test the apparatus and investigate the effects of air flow rate and temperature on the ISTD process. Following the preliminary experiments, a mercury off-gas treatment system was added and mercury experiments were conducted. Experiments performed using elemental mercury showed greater than 99.8% removal of the mercury from Ottawa sand. These results show that ISTD can remove mercury from soil at temperatures well below its boiling point and that perfluorodecalin can be used as a surrogate for elemental mercury in laboratory experiments. A flow and transport simulator was used to model the results from both the perfluorocarbon and the mercury experiments.     

络合混凝法去除香菇多糖中的镉污染

目的对香菇多糖提取过程中重金属的去除方法进行研究。方法在提取香菇多糖过程中使用络合以及混凝吸附的方法对香菇多糖粗提液进行处理,去除重金属镉(Cd),并对去除过程中p H值、试剂浓度以及KMn O4预氧化的作用进行了调查。结果香菇多糖提取过程中重金属镉的去除的工艺为:使用0.5 mg/L KMn O4预氧化30 min,在p H 10.0条件下使用络合剂25 mmol/L EDTA和25 mmol/L柠檬酸钠以及混凝剂50mg/L活性炭处理1 h;此工艺下香菇多糖中Cd的去除率高达96.3%。结论本研究为香菇以及其他食材、药材中重金属污染的处理问题提供了新的方法。     

Detection of chicken meat in raw meat mixtures by a sandwich enzyme immunoassay

A double-antibody sandwich ELISA (enzyme-linked immunosorbent assay) has been successfully developed for the detection of low levels of chicken meat (1–30%) in unheated meat mixtures. The assay uses chicken-specific antibodies, obtained by immunoadsorption of the crude chicken antisera onto immobilized sarcoplasmic extracts from beef, pig and horse, to remove cross-reacting antibodies. The purified antibodies, bound to the wells of a microtitre plate, sequester chicken muscle soluble proteins from saline extracts of meat mixtures. Immuno-recognition is made with similar purified antibodies conjugated to the enzyme horseradish peroxidase. Subsequent enzymic conversion of substrate gives clear optical density differences, when assaying minced beef and pig containing variable amounts of chicken meat.     

Field column study using zerovalent iron for mercury removal from contaminated groundwater

Passive in situ remediation technologies, for example, permeable reactive barriers, PRBs, are an attractive and less expensive alternative compared to conventional pump and treat systems for groundwater remediation. Field column experiments were conducted to evaluate the removal of dissolved mercury from groundwater using zerovalent iron as the reactive media. Two column tests were conducted over a 6-week period, which simulated 2 and 10 years of groundwater flow through a potential full-scale treatment system. The influent groundwater pH was 7.8-9.5. The groundwater was reduced with an Eh, corrected to the standard hydrogen electrode, ranging from 0 to 120 mV over the trial period. Prior to treatment the total mercury concentration of the groundwater was approximately 40 microg L(-1). Effluent from the 10-year simulation contained approximately 0.5 microg/L of mercury during the first 3 weeks and increased to as much as 4 microg L(-1) by the end of the testing period. Effluent from the 2-year simulation was generally < 0.1 microg L(-1). Profile sampling of the 2-year simulation suggests that most of the mercury removal occurred in the initial 50% of the 20 cm column. Mineralogical studies, conducted using SEM/EDS and X-ray absorption spectroscopy (XAS), confirm the accumulation of mercury onto a zerovalent iron surface in this 20-cm zone. These analyses indicate that mercury accumulated as a mercury sulfide with a stoichiometery similar to those of cinnabar and metacinnabar (HgS).     

Volatilization and recovery of mercury from mercury wastewater produced in the course of laboratory work using Acidithiobacillus ferrooxidans SUG 2-2 cells

The iron-oxidizing bacterium Acidithiobacillus ferrooxidans SUG 2-2 is markedly resistant to mercuric chloride and can volatilize mercury (Hg0) from mercuric ion (Hg2+) under acidic conditions. To develop a microbial technique to volatilize and recover mercury from acidic and organic compound-containing mercury wastewater, which is usually produced in the course of everyday laboratory work in Okayama University, the effects of organic and inorganic chemicals on the mercury volatilization activity of A. ferrooxidans cells were studied. Among 55 chemicals tested, the mercury volatilization from a reaction mixture (pH 2.5) containing resting cells of SUG 2-2 (1 mg of protein) and mercury chloride (14 nmol) was strongly inhibited by AgNO3 (0.05 mM), K2CrO7 (1.0 mM), cysteine (1.0 mM), trichloroethylene (1 microM), and commercially produced detergents (0.05%). However, the strong inhibition by trichloroethylene and detergents was not observed when these organic compounds were chemically decomposed using Fenton's method before the treatment of the wastewater with SUG 2-2 cells. When 20 ml of water acidified with sulfuric acid (pH 2.5) containing ferrous sulfate (3%), diluted mercury wastewater (17.5 nmol of Hg2+) and SUG 2-2 cells (0.05 mg of protein) were incubated for 10 d at 30 degrees C, 47% of the total mercury in the wastewater was volatilized and recovered into a trapping reagent for metal mercury. However, when the organic compounds in the mercury wastewater were decomposed using Fenton's method and then treated with A. ferrooxidans cells, approximately 100% of the total mercury in the wastewater was volatilized and recovered.     

Removal of Salmonella Enteritidis from commercial unpasteurized liquid egg white using pilot scale cross flow tangential microfiltration

Effectiveness of a cross flow microfiltration (MF) process for removal of a cocktail of Salmonella enterica serovar Enteritidis species from commercial unpasteurized liquid egg white (LEW) from a local egg breaking plant, while maintaining its functional properties was evaluated. To facilitate MF, LEW was wedge screened, homogenized and then diluted (1:2 w/w) with distilled water containing 0.5% sodium chloride. Diluted unpasteurized LEW was inoculated with five strains of S. Enteritidis (ATCC 4931, ATCC BAA-708, ATCC 49215, ATCC 49218, and ATCC BAA-1045) to a level of approximately 10⁷ CFU/mL of LEW and microfiltered using a ceramic membrane. Process parameters influencing egg white functional properties and pathogen removal efficiency were evaluated. Average permeates flux increased by almost 126% when pH of LEW was adjusted from pH 8 to pH 7 at 25 °C. Microbial removal efficiency was at least, on average, 6.8 Log₁₀ CFU/mL (limit of detection ≤ 0.5 Log₁₀ CFU/mL). Functional property analysis indicated that the MF process did not alter the foaming power of LEW.