<正>(接2010年6期《新饲料》第55页)5.4抗萘啶酸的鼠伤寒沙门(氏)杆菌的回收率经过不同条件的膨化程序,我们可以从膨化出的饲料中回收膨化前没有被发现的鼠伤寒沙门氏菌的细胞(如表3)。

Although numerous studies have documented the use of surrogate organisms for the evaluation of pathogens in human food, reports on the use of such organisms for similar studies in animal feed are limited. In the current study, dry feed inocula of Salmonella Typhimurium cells or Bacillus stearothermophilus spores were prepared and used to evaluate the efficiency of sterilization during feed extrusion. The inocula were placed in sealed stomacher bags and kept under 4° C refrigerated storage, where they remained stable for the 8-wk study period. Test feed batches were inoculated with the dry feed inocula of Salmonella Typhimurium or B. stearothermophilus spores, and the batches were then extruded by using a single-screw extruder set to various processing stringencies according to a designed experimental protocol. Only thermophilic B. stearothermophilus could be recovered from the test feed samples over the entire range of extrusion processing stringencies used (245 to 345 g of moisture/kg of feed; 3 to 11 s of feed retention time in the extruder barrel; and 77 to 110° C extruder barrel exit temperature). It was concluded that B. stearothermophilus is a suitable surrogate organism for evaluating the sterilization efficiency of feed extrusion and for identifying the optimal processing conditions to use during feed extrusion to eliminate, or at least minimize, the incidence of mesophilic and thermotolerant pathogens in feed.

Soft shell clams, Mya arenaria, are found from Canada to North Carolina on the U.S. Atlantic Coast and from Canada to California on the U.S. West Coast. They are also found in several other parts of the world including Europe. The primary market for these clams on the U.S. East Coast is in New England. Clams are sold whole live or in one of the several cooked forms. Commercial soft clam shucking and processing is primarily by manual methods. However, physical properties data for these clams is lacking and is a constraint on the automation of processing. Several properties of soft shell clams harvested from five different harvest locations in the Chesapeake Bay are detailed in this paper and relationships between the components of the clam are defined mathematically through regression equations. The live weight and the clam length are related to shell weight, siphon weight, meat weight, total solids and free water in the clams. Meat yields under both standard processing methods and for clams steamed and consumed with only the shell removed are detailed. The effect of harvest area on the clam parts is also defined. Soft shell clams shucked manually result in a meat yield of approximately 29% of the live weight. If steamed and eaten the meat yield may be as high as 43% of the live weight, primarily because the siphon is often consumed in steamed clams.

Salmonella and other pathogenic organisms that infect poultry and other livestock can originate from feed and environmental sources. Thus, measures are taken to control Salmonella infection in animals to improve food safety and reduce production losses. The current study was designed to investigate and optimize extrusion conditions for reducing bacterial counts in a surrogate feed matrix. A single-screw extruder was used to process feed artificially inoculated with Bacillus stearothermophilus 12980 (ATCC, Reston, Virginia). Preliminary experiments demonstrated that Salmonella typhimurium (S. typhimurium NALr) was eliminated from feed under conditions of moderate extrusion stringency (285 g moisture/kg mash feed, 83 °C extruder barrel exit temperature, 7 s retention time in the extruder barrel) and, therefore, a more thermotolerant organism was required to conduct the study. Spores of B. stearothermophilus 12980 inoculated into a surrogate feed matrix consisting of 600 g maize meal/kg, 300 g soya bean meal/kg and 100 g animal protein blend/kg, respectively, was used to investigate the effect of three extrusion variables on microbial killing. The three variables were extruder barrel exit temperature (T), mash feed moisture content (Mc), and mean retention time of feed in the extruder barrel (Rt). A rotatable central composite statistical design was used with three independent variables and five levels each. The quadratic response surface model fit to spore count data was used to predict extrusion conditions that maximized bacterial killing. The response surface indicated a stationary point within the design region that was a saddle. An estimated ridge of maximum killing indicated that a maximum reduction of 1.03 log cycles would occur under the following extruder settings: T = 110 °C, Mc = 245 g/kg and Rt = 11 s. Because the moderate stringency condition (T = 83 °C, Mc = 285 g/kg and Rt = 7 s) completely eliminated detectable S. typhimurium in the test feed matrix, it would appear that all S. typhimurium cells and all mesophilic organisms of similar thermal tolerance would be eliminated at most extruder conditions within the central composite design region.

Poultry transport containers (PTC) require thorough cleaning and disinfection to eliminate the risk of introducing foodborne pathogens into the poultry processing line. The design, materials, and construction of a prototype decontamination tank developed for cleaning and disinfecting PTCs arc described in this study. The decontamination tank (3.4 x 2.2 x 2.2 m) was made of steel-reinforced fiberglass. It consisted of a rectangular holding section with a capacity of 16,000 L of water in which the PTCs could be immersed. A flat fiberglass mesh was provided at the lower end of the rectangular tank along with a sloped section to drain the solids washed from the PTCs. Three levels of CPVC pipelines were established on the inside tank walls, each containing several nozzles through which recirculated water could be sprayed to create agitation inside the tank. One level of stainless steel steam pipeline with nozzles inserted periodically was provided on the inside tank wall to deliver steam to increase the tank solution temperature. A thermostatic valve provided on the steam line controlled the supply of steam and regulated the tank solution temperature with an accuracy of +/-3degreesC. The tank was made portable (with a forklift) by providing two hollow steel tubes beneath the tank for the forklift arms. The entire decontamination tank was supported on horizontal steel members so that the weight distribution was even on the ground and to ensure that the tank could be installed on an unpaved surface. After construction, the tank was transported and installed at a poultry processing facility All the essential functions planned for the tank by the project investigators were accomplished, including supply of water and steam, holding of tank solution, maintenance of water temperature up to 70degreesC, recirculation and agitation of the tank solution, immersion and retraction of PTCs, and resistance to 70degreesC and 1000 ppm of chlorine. It is suggested that this decontamination system could be further modified, standardized, and adapted for use in poultry processing plants to clean and disinfect PTCs.

Poultry transport containers (PTC), when not adequately cleaned and disinfected each time after hauling live birds, carry the risk of introducing foodborne pathogens into the poultry processing plant as well as injecting subsequent batches of transported birds. In the apparent absence of a satisfactory system, we have evaluated a two-step decontamination process for cleaning and disinfecting PTCs using a recently developed, novel prototype decontamination unit. The PTCs were first manually cleaned with a high-pressure jet spray (6 MPa) of disinfectant solution and subsequently immersed in either hot water (24degreesC, 50degreesC, 60degreesC, and 70degreesC) or a sodium hypochlorite solution (0, 500, 750, and 1000 ppm at an ambient temperature of 24degreesC). Both conditions (heat and chemical) were tested at 0.5, 1, and 2 min contact times. Salmonella and/or coliform counts were determined before and after pressure-washing and after immersion treatment. In the absence of large numbers of Salmonella, coliform counts were used to determine cleaning and decontamination efficiency. Pre-cleaning PTCs with a high-pressure jet spray of the disinfectant solution did not produce significant reduction (alpha = 0.05) in coliform populations. However, immersing pre-cleaned PTCs in hot water at either 60degreesC or 70degreesC reduced col form concentrations an average of 1.6 logs (P < 0.05) within 0.5 min. Similarly, immersing the PTCs in a sodium hypochlorite solution at 1000 ppm for 2 min at a mean tank temperature of 28degreesC significantly, reduced coliforms by an average of 4.2 logs (P < 0.05). It was concluded that either heat or chemical treatments reduced coliform counts enough to reduce the risk of cross-contamination significantly. This prototype decontamination system can be further modified and is adaptable for use in poultry processing plants for cleaning and decontamination of PTCs.

The broiler industry is seeking effective and economical methods to minimize production heat losses. Poultry exposed to heat stress pant and experience reduced blood carbon dioxide concentration, suggesting that supplementing birds with carbon dioxide would be beneficial. Chilled drinking water also has a potential to reduce heat stress. The present studies seek to determine the effectiveness of offering carbonated or reduced-temperature water to two broiler flocks raised to 42 days of age. Bird production performance data obtained from the two studies were combined since environmental temperatures during both studies were mild with little heat stress activity, except for a sudden increase in environmental temperatures on day 38 in the second study. There were no significant differences in live weight, cumulative mortality, and feed-to-gain ratio at harvest when data obtained from the two studies were combined. Birds provided chilled drinking water showed a 1.2 L/bird greater cumulative drinking water use than those provided tap water at ambient temperature. Ambient air temperatures were between 29 degreesC and 37 degreesC during the hottest periods in either study. Reduced-temperature carbonated drinking water had better retention of dissolved carbon dioxide, as indicated by significantly lower pH (p < 0.001, at alpha = 0.050) when compared with ambient-temperature carbonated drinking water.

Thickness variation of chicken fillet is a major challenge to X-ray detection of embedded bone fragments. As a novel solution, combined x-ray and laser range imaging has been developed for thickness compensation effectively. In order for this synergic technology to work successfully for on-line industrial applications, the vision system should have viable real-time capabilities and be able to detect a variety of physical hazards. In this paper, a multithread scheme is developed for real-time image processing, implementation and performance of which are also presented. A rule-based approach is formulated under a unified framework for detection of diversified subjects, and performance of this framework is also discussed.

Effective and economical techniques to minimize production losses that result from heat stress are important in the broiler industry. Zone cooling, as opposed to whole-house cooling, during hot weather may be effective in relieving heat stress. The present studies seek to determine the effectiveness of such a practice. Two flocks (I and 2) were raised sequentially for 42 days. Studies were analyzed separately, and when the results of the two studies were consistent, a combined analysis was completed and reported. Means comparison tests were completed on production parameters at harvest (day 42). Cool roost birds showed greater live weight and roost use, lower mortality, and lower feed-to-gain ratios than ambient roost and floor birds, respectively. The parts yield analysis showed that wing weight was greater in the floor-raised birds than in either the cool roost or ambient roost raised birds in flock 1. In flock 2, the cool roost birds showed a greater breast meat weight than the ambient roost birds. The cool roost system appeared to be more efficient at relieving heat stress at temperatures below 30 degreesC than at temperatures above 30 degreesC. Heat loss through the feet of birds ranged between 0.65 and 5.09 watts per bird during week 6 in either flock (chamber air temperature varied from 29 degreesC to 37 degreesC). Moisture condensation on the cool roost system did not significantly increase the litter moisture content in the cool roost treatment beyond that of the ambient roost system.

A prototype system for the cleaning and decontamination of poultry transport containers was previously developed and evaluated as a means of eliminating foodborne pathogens entering poultry processing plants. While decontamination of the containers once with the use of either hot water (up to 70 degrees C) or sodium hypochlorite (up to 1,000 ppm) resulted in significant reductions in the numbers of coliforms and the elimination of small numbers of Salmonella, complete removal of pathogens was not attained. Therefore, the present study was conducted to determine whether repeated decontamination of the same containers could eliminate coliforms and Salmonella consistently. Individual five-tier containers consisting of galvanized steel frames and fiberglass floors were identified (n = 6) and decontaminated once per day for five consecutive days after being used to haul broilers from farms to the processing plant. Two types of containers were tested in this study: one had previously been used for broiler transportation, and the other had new floors. After each transport, the containers were first precleaned with a cleaning agent using a high-pressure jet (6,094 kPa) to remove debris and to loosen biofilms from surfaces. The containers were then immersed in an aqueous solution of 1,000 ppm of sodium hypochlorite at 70 degrees C for 2 min. Samples obtained from the container surfaces before and after each cleaning and decontamination were analyzed to obtain coliform and Salmonella counts. Coliforms were completely eliminated from both types of containers following one decontamination treatment. Because no Salmonella were detected on the containers, the effect of decontamination in the elimination of Salmonella was not determined. Similar treatments on five successive days also resulted in poultry transport containers that were essentially free of Salmonella and coliforms. This decontamination system involving a combination of heat and sodium hypochlorite can be used as a standard method for cleaning poultry transport containers in the poultry industry. It is recommended that such containers be cleaned after each use to avoid the potential risk of a buildup of significantly higher loads of pathogenic microorganisms and their biofilms.

Containers used in transporting live poultry between production and processing units are a primary source of contamination for processed poultry products. Because disinfection of transport containers (TC) has been difficult to accomplish, it is probable that the choice of appropriate disinfectant and its application are partially or wholly responsible for the failure to adequately eliminate pathogens from TC. Therefore, 13 commercial disinfectants were selected and evaluated for their capacities to destroy Salmonella. The disinfectants were applied in various concentrations on prescribed areas (10 cm diameter circle) of galvanized steel surfaces (representative of TC material) that were artificially contaminated with Salmonella (10(8) cfu/mL) with a mixture of organic material. Likewise, coupons (1.9 cm2) made of the same metallic surfaces and covered with biofilms of Salmonella spp. were tested in the same manner for each disinfectant. Two of the disinfectants completely eliminated Salmonella on the artificially contaminated and biofilm-covered surfaces. These compounds produced logarithmic reductions in Salmonella populations as high as 7.18 within 2 min. One of the two effective disinfectants contained sodium hypochlorite and was effective at a concentration of 0.05% (vol/vol). The other disinfectant was an alkaline peroxide compound and was effective at a concentration of 1% (wt/vol). Evaluation of these two disinfectants under simulated conditions suggested that application under the prescribed regimen could result in effective elimination of Salmonella from TC within a limited period.

A water displacement system was developed to calibrate variable area airflow meters. Time, temperature, pressure, and volume were the only measurements required to determine airflow through the system. System accuracy was estimated by comparing meter flow against a rotameter previously calibrated using a Hastings-Raydist System. Results obtained showed this system to be highly reliable and usable over a wide range of flow rates.

Laboratory experiments were conducted to measure amounts of ammonia volatilized from loamy sand soil using an airflow technique. A composite rotatable statistical design was used to define the relationship between ammonia volatilization (Z, kg-N/ha) and temperature (degrees-C), soil pH, initial soil moisture content (MC, g water/100 g dry soil), urea application rate (R, 7-N/ha), and urea application depth (D, cm). Soil samples were treated to adjust the sample parameters (i.e., soil pH). Each soil sample was placed in a small container and the containers were placed in an environmentally controlled room. Air was passed through each container and the ammonia volatilized from the soil in the container was trapped in an acid bath. The acid baths were analyzed periodically to determine the amount of ammonia released by the soil. Curves defining the release of ammonia with time were plotted from the results. Using regression techniques, a response surface was developed that defined accumulated ammonia volatilization over a 15-day period as a function of the independent variables. The response surface is defined by the following equation.

Laboratory experiments were conducted to measure amounts of ammonia volatilized from loamy sand soil using an airflow technique. A composite rotatable statistical design was used to define the relationship between ammonia volatilization (Z, kg-N/ha) and temperature (degrees-C), soil pH, initial soil moisture content (MC, g water/100 g dry soil), urea application rate (R, 7-N/ha), and urea application depth (D, cm). Soil samples were treated to adjust the sample parameters (i.e., soil pH). Each soil sample was placed in a small container and the containers were placed in an environmentally controlled room. Air was passed through each container and the ammonia volatilized from the soil in the container was trapped in an acid bath. The acid baths were analyzed periodically to determine the amount of ammonia released by the soil. Curves defining the release of ammonia with time were plotted from the results. Using regression techniques, a response surface was developed that defined accumulated ammonia volatilization over a 15-day period as a function of the independent variables. The response surface is defined by the following equation. Ln(Z + 11) = - 0.935 - 0.0417T + 0.570 pH + 0.003671 + 0.178 MC - 0.445D + 0.00154 (T)2 - 0.00739 (MC)2 + 0.0285 (D)2 - 0.000378 (R)(D)

ABSTRACT Volatilization of ammonia from poultry litter in broiler houses creates potential health hazards for the house operator and the birds. This problem was addressed by defining atmospheric ammonia concentrations from broiler litter as a function of environmental variables. Nine chambers, each 1.37 m in volume, were constructed and positioned in a common room. Air temperature and relative humidity in the common room were controllable. Air flow (i.e., ventilation) rates through each chamber and the litter moisture content in each chamber were also controllable. An attempt to control litter pH was not successful. Using a second-order central composite rotatable statistical design, data were collected from the small chambers that allowed both litter pH and ammonia volatilization rate to be expressed as a function of litter moisture content, ventilation rate, and air relative humidity and temperature. Response surfaces developed from this data are presented.

ABSTRACTMathematical models are often used for determining commercial thermal process schedules for heterogeneous foods processed in an aseptic processing system. the particle/fluid interface convective heat transfer coefficient is a critical input parameter for these models and must be determined experimentally. Experiments were conducted at 129.4°C in a specially designed apparatus to determine the particle/fluid interface convective heat transfer coefficient for model food particles heated by Newtonian and non‐Newtonian fluids. Values of the heat transfer coefficient ranged between 55.63 and 89.5 W/m10C for particles heated in a non‐Newtonian fluid and between 65.67 and 107.11 W/m20C for particles heated in a Newtonian fluid.

The response of an ammonia gas sensing electrode was measured automatically using a simple FET (field-effect transistor) operational amplifier (op-amp) circuit, a data acquisition and controls system (Cyborg ISAAC 2000), and an IBM-PC. It is possible to measure the chemical concentrations of various solutions faster and more conveniently using the system described than by using conventional methods that involve a pH/digital voltmeter. This system permits development of automated ammonia concentration control, a particularly valuable attribute in recirculating aquaculture systems

A model for predicting the vertical temperature profile of turbid freshwater ponds is described. High resolution in space and time and a reduction in the number of meteorological inputs usually required by such models is achieved by using pond surface temperature as a model input. A method to estimate hourly surface temperature is proposed and demonstrated.