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Science Platforms > RPPROCA Food Processing Completed Projects PR-0004-10/93 The objective of this project was to identify factors that affect the temperature profile of food materials during ER heating, and to develop techniques for obtaining temperature profile during ER heating. ER or ohmic heating is a promising technique for thermal processing of particulate foods. Theoretically, it is possible for food particulates with uniform electrical conductivity to heat evenly. The establishment of an approved process would be simplified because the liquid temperature could be used for lethality calculations. The objectives of the project were to develop techniques for measuring temperature profile of samples during processing and identify safety parameters. The project developed the multipoint (MP) probe and advanced the development of liquid crystal (LC) sheets and magnetic resonance imaging (MRI). They were capable of measuring 1-, 2- and 3-dimensional temperature profiles, respectively. The development of the MRI for temperature measurement was not finished while the other two were completed and are being used in various applications. Studies on tortuousity, shadowing effects and convection were conducted to understand safety factor in ER processing. Results showed that in food systems consisting of solids from various materials, shadowing effects could make the cold spot develop in solids with high electrical conductivity. This is an important finding since the rule of thumb in ER processing is that the cold spot develops in components with low electrical conductivity. A study on the effects of no, free and forced convections and conductivity ratios showed that the location of the cold spot (between solid and liquid) was not affected by convection but rather by conductivity ratio. PR-0006-10/93 The fumonisins are mycotoxins produced by Fusarium moniliforme and other Fusarium species in corn. Fumonisins have been implicated as the causal agents in a variety of animal and human diseases. The main objective of this study was to determine the effects of thermal processing on the stability of fumonisin B1 (FB1) spiked into corn-based foods. Processes that were studied included extrusion, frying and canning. FB1 loss in the extruded grits ranged from 43 to 70%. For samples extruded in the mixing and non-mixing modes, extrusion temperature and moisture levels had no significant effects on FBI degradation. No significant losses of FBI were found when corn masa was fried at 140-170°C for 0 to 6 min. FB1 began to degrade at frying temperatures > 180° C and times > 6 min. Canning had little effect on FB1 levels in whole and creamed corn. These processing studies suggest that fumonisins are heat stable compounds under most food processing conditions. PR-0011-10/95 The objectives of this project were to (1) Develop methodology and software based on multivariate statistical techniques for modeling and quantitative characterization of food processes to determine target values and to monitor critical control points (CCP), and (2) Develop interactive software to warn process operating personnel before noncompliance occurs and to diagnose most probable causes of the disturbance. Methods and software have been developed for statistical monitoring of CCPs and fault diagnosis by using multivariate statistical techniques. These methods indicate accurately and quickly the existence, magnitude and occurrence times of critical changes in process operation and probable causes for abnormal operation. The developed software integrates and automates monitoring of CCPs and determines the probable source causes for abnormal behavior in real-time, in a production environment. These methods will facilitate the determination of target values based on historical process data, monitoring of critical limits, and enable the diagnosis of most likely causes of abnormal process operation. The methodology and software developed were tested first by using simulation studies based on dynamic process models, then by experimental studies in pilot scale experimental systems and industrial processes. Data were collected from the high temperature, short time pasteurization pilot plant located at the NCFST, and the Armour Swift-Eckrich Brown-N-Serve plant. Methodology for complementing the intermittent CCP monitoring of internal sausage temperature was developed by monitoring of external sausage temperature using an infrared thermometer. This system measures continuously the external sausage temperature and is able to detect changes that may indicate an out-of-control process and a violation of the CCP. Using the developed programs, the operating conditions of the process can be continuously monitored and excess waste of product can be reduced. The process monitoring tools are being integrated to a real-time knowledge-based system that provides a supervisory level for coordinating various activities and additional tools for fault diagnosis. PR-0012-10/96 The objectives of the study were to evaluate on-line sensors and technologies to more easily monitor and control the processing conditions used in the manufacture of food products, and to validate techniques to monitor and control the processing conditions used in the manufacture of food products. Advanced computer control strategies are now available or being developed to improve food quality and reduce the cost of processing. However, the food industry and regulatory agencies must address food safety concerns before these techniques can be applied to commercial processes. Catastrophic disturbances that could be caused by loss of electricity, steam pressure, vacuum, or air pressure could result in process deviations that are above the critical control limit and beyond the ability of these control systems to quickly respond. These process deviations could result in under-processed product that must be prevented from entering the food supply. Control for these catastrophic disturbances must be instantaneous to segregate under-processed food products. Products processed above the critical control limits could be automatically diverted to segregate under-processed product. In this study, the on-line temperature and pressure sensors were able to detect defects in a steam seal gasket of an aseptic pasteurization system as small as 1.5 mm. These results provide preliminary evidence that the temperature and pressure sensor and the monitoring technique can be effectively used to detect steam seal gaskets defects that could cause process deviations. These results provided the basis of proposing a new project "Monitoring and Control of Flow Diversion Valves for the Aseptic Processing of Dairy Products" that was accepted by the NCFST TAC. PR-0013-10/96 This work is continuing at the NCFST under a new project number, PR-0020 with new funding and slightly modified objectives. The following is a summary of current project status. Mycotoxins are a chemically diverse group of secondary metabolites produced by fungi. They are responsible for significant financial losses for the food industry and pose a threat to human and animal health. The objectives of this project were to 1) study the effects of processing/chemical treatments on fumonisin in corn-based food and patulin in apple cider/juice, 2) participate in surveys for fumonisin and patulin in food, 3)correlate apple quality with patulin levels in juice/cider, and 4) determine the effects of washing treatments on patulin levels in cider made from contaminated apples. We found that fumonisin is fairly heat stable under most conditions encountered during thermal processing (e.g. boiling, retorting, baking and frying) but may be destroyed during extrusion cooking. Adding glucose to contaminated corn grits enhanced destruction of fumonisin during extrusion. In dry milling experiments, fumonisin tended to concentrate in bran, germ and fine fractions of naturally contaminated corn. Work on the stability of patulin has shown that the compound is stable under pasteurization temperatures/times. However, addition of ascorbic acid to juice may result in losses of patulin. Surveys conducted of corn-based foods and apple juices/ciders purchased in the Chicago area indicated that most foods contained low levels of fumonisin or patulin. High levels of fumonisin (>3 ppm) were found in samples of blue and high-lysine corn meal. Several lots of a generic brand of apple juice contained high levels of patulin (>30 ppb). In several experiments, we found that cider made from dropped apples had significantly higher patulin levels than cider pressed from tree-picked fruit. Washing the dropped apples with water and chlorine solution before pressing, appeared to lower patulin levels in the cider. More work is needed understand the effects of processing on mycotoxins and to identify methods for reducing mycotoxin levels in food. PR-0015-10/97 The objectives of this study were to develop and evaluate alternative/improved methods to more effectively monitor and control flow diversion systems for the aseptic processing of food products, to evaluate on-line sensors and technologies to more easily monitor and control the processing conditions used in the manufacture of food, and to validate techniques to monitor and control the processing conditions used in the manufacture of food products. Studies monitoring the performance of a flow diversion valve (FDV) were completed. Using a 1.5 mm defect in the product gasket and various initial pressures, no changes in the leak detect valve (LDV) temperature or LDV pressure were observed. Using the 5 mm or 10 mm defect in the product gasket, LDV temperature decreased as the FDV pressure was increased. At low initial steam pressures (0.013-.040 bar), the LDV pressure decreased at first and then increased as the FDV pressure was increased. At medium initial steam pressures (0.66-1.33 bar), the LDV pressure decreased as the FDV pressure was increased. In summary, size of defect in the gasket and the differential between FDV pressure and steam seal pressure in the LDV affected the temperature and pressure of the steam seal area. The on-line temperature and pressure sensors were able to detect defects in a steam seal gasket of an aseptic pasteurization system as small as 5 mm. PR-0016-10/98 The objectives of this project are to develop a model system to study sanitation and biological growth, and to study the efficacy of ozone and other sanitizing chemicals as substitutes for chlorine against biological growth on food contact surfaces. Bacteria along with fat, protein and other debris form a persistent biofilm on food contact surfaces which are not normally removed by routine cleaning. Currently high temperature chlorinated water is used widely in the food industry to sanitize processing equipment or processing lines. Although this technique is generally effective there are disadvantages associated with it, including a concern that more resistant and virulent strains of bacteria are emerging because disinfectants and sanitizers (such as chlorine) have been used repeatedly. In June 1997, the Electric Power Research Institute Expert Panel submitted a petition to FDA proposing that the uses of ozone should be considered as GRAS (generally recognized as safe). The potential of ozone has been shown to be an effective replacement for chlorine to sanitize food contact surfaces. A concentration as low as 0.1PPM effectively removes high organic content biofilms on the food contact surfaces. Ozone was shown to be a more powerful disinfectant than chlorine. Some limited laboratory work has been conducted on the use of ozone as a sanitizer against biofilms on stainless steel plates with pure non-pathogen cultures. There is no further information about the efficacy of ozone with food pathogens on different material surfaces. Furthermore. no work has been undertaken to date to evaluate the effects of temperature, pH, contact time, quality of surface, food soils, and background microflora on bacteria removal. There is also a lack of adequate information on corrosion data on the effect of ozone on food contact surface materials. It is the purpose of this study to provide the basis for the effective and safe utilization of ozone as a replacement for chlorine. The application of ozone sanitation is now gaining interest by food industry. PR-0017-10/98 Various research reports have raised concerns about the public health protection provided by the current 60-day aging period in the manufacture of hard cheeses made with unpasteurized milk. Salmonella typhimurium, Listeria monocytogenes, and Escherichia (E.) coli O157:H7 have been shown to survive aging for 5 to 15 months. The purpose of this study is to investigate the adequacy of the 60-day minimum aging to eliminate the foodborne pathogens. Even at the 101 inoculation level into raw milk, E. coli O157:H7 populations increased by 1 to 2 logs at the milling and pressing steps. Populations of E. coli O157:H7 in cheese aged for 60 days at 7ºC were reduced by less than 1 log. This population increase during cheese making, and decrease during the 60 days aging resulted in no net change. After 300 days, no growth of E. coli O157:H7 was seen on the plates after either pre-enrichment or enrichment. The evaluation of the adequacy of the minimum aging period of hard cheeses made from milk thermalized to eliminate food pathogens was not completed because of need to decontaminate the pilot plant before extensive remodeling of the Biocontainment Pilot Plant (BCPP) could begin. The validation of techniques to monitor and control the processing conditions used in the manufacture of hard cheeses will be conducted as a regulatory review of computer records documenting the steps of cheese making. PR-0018-10/99 The objectives of this project are to evaluate the effectiveness of UV light in delivering a 5-log reduction on a target microorganism and to develop a technique in determining dosage delivery. The Federal Register (April 24, 1 998) reported several cases of illness resulting from consumption of various types of juices, mostly unpasteurized apple cider. UV light disinfection is a nonthermal process which involves the exposure of pathogenic microorganisms light radiation, between 200-400 nm. UV light inactivates microorganisms by attacking their DNA, which renders them incapable of reproduction. A big obstacle in the application of UV light processing in fruit juices is the low transmittance at the UV range. For UV processing to be effective, the required dosage at specified wavelength must be delivered. A major focus of this project is to develop protocols to validate the UV dose for destruction of pathogens. Effectiveness of UV light against target pathogens and surrogates will be evaluated using a continuous type UV reactor. Chemical actinometry will be used to measure radiation dose in juices subjected to UV radiation. Natural components of juice will be monitored for suitability to use as radiation markers. Degradative photochemical reactions, such as browning and vitamin deterioration, will be studied in juices subjected to UV processing. Investigators also plan to submit a proposal for external funding at a later date. The most effective wavelength for disinfection is about 254 nm and it is usually produced using low pressure mercury lamps. However, the use of broader band light sources, i.e. medium pressure mercury lamps, which produces UV light at the range of 200-400 nm has been found effective against microorganisms that require high dosage for inactivation, e.g. cryptosporidium. PR-0019-10/99 The objective of this project is to further the development of magnetic thermometry for food processing. This method will allow for the interior temperature of test objects to be determined as they move through processing lines without contact. Some magnetic materials create temperature dependent magnetic fields that penetrate conducting materials. By measuring the size of the surrounding magnetic fields, one can determine the temperature of the magnet without contact to the magnet or an object that contains the magnet. Since the magnet can be small and is a solid piece of material it has several advantages, 1) the electronics do not need to travel with the magnet through harsh environments, 2) the magnet can be placed in suspended solids with minimal effect on their motion. The remaining part of the magnetic thermometer consists of a magnetometer that is consistent with the working environment. The magnetometer needs to account for the velocity, position and orientation of the magnet when these quantities are unknown. The result is that by simply moving the magnet past the sensor the temperature of the magnet is determined. At the NCFST a prototype magnetic thermometer has been built to measure temperatures in objects moving through 2" or smaller pipes. The prototype has worked successfully in industrial environments but its performance must be improved. Because of the necessity to have product flow into and out of the sensor, interference can never be perfectly shielded. However, there are ways to improve the shielding and the measurement=s immunity to external noise. The magnetic shield can be lengthened and a second layer can be added. By changing the triggering method and data analysis, one can reduce the effect of unshielded signals as well. This should help the system measure smaller magnetic particles or similar sized particles at increased distances. This project should develop a system that would be compatible with other applications as well. PR-0020-10/99 The objectives of this project were to determine the effects of thermal processing and chemical treatments on moniliformin, zearalenone, and other mycotoxins, to study the effects of electron beam irradiation in combination with peroxide treatments on aflatoxin levels in contaminated grain, and to correlate patulin levels and fruit quality to microbial quality of apple cider. Mycotoxins are a chemically diverse group of secondary metabolites produced by fungi. They are responsible for significant financial losses for the food industry. Mycotoxins pose a threat to human and animal health, and the determination of methods for reducing the mycotoxin content of food is desirable. In addition, there is a need to develop a data base on the occurrence and levels of mycotoxins in processed food. In the past, work done at the NCFST has mainly focused on the effects of thermal processing and chemical treatments on fumonisin in corn products. More work is needed understand the effects of processing on mycotoxins and to identify methods for reducing mycotoxin levels in food. Little is known about the effects of thermal processing on moniliformin, zearalenone and other mycotoxins. Although there have been some reports on the destruction of aflatoxin and other mycotoxins with gamma irradiation, little is know about the effects of electron beam irradiation in combination with chemical treatments on mycotoxin. Finally, more work is needed to determine if patulin levels can be used to predict the microbial quality of apple cider and other juices. PR-0021-10/00 The objectives of this project were to evaluate, in a systematic and comprehensive manner, a number of different bacterial species for use as surrogates for a diverse range of bacterial pathogens, under specific food processing parameters and develop a standard set of surrogate organisms for use in process development and validation. The following assesments were completed: 1) temperature resistance comparison of four types of foodborne pathogens and four strains as potential surrogates for those pathogens; 2) attachment/hydrophobicity assessment of four foodborne pathogens and four strains for possible use as surrogates; and, 3) assessment of desiccation resistance in four types of foodborne pathogens and four candidate surrogate strains. The results from these assessments were tabularized for easy reference. PR-0022-10/00 1) Quantify the effect of processing parameters on microbial destruction, dissolved gases, pH and viscosity. 2) Evaluate effect of parameters on quality attributes. PR-0023-10/00 This study will generate data for assessing the effects of the irradiation on chemical changes in the color additives (Chromophtal yellow 2RLTS (Yellow 110 - 2,3,4,5-tetrachloro-6-cyanobenzoic acid) and Irgalite Blue GBP (copper (II) phthalocyanine blue)) and use the data to help refine existing migration models used to support FDA's review of food additive petitions and food contact substance notifications. Gamma irradiation did not affect the IR spectra of pure colorant and PS test specimens measured in a range of 550-4000 wavenumbers. Qualitatively, the HS/GC/MS results suggest that irradiation did not generate new chemicals. Volatiles detected in irradiated test specimens (PS sheets and colorants) are alcohols, aldehydes, ketones, aromatic and aliphatic hydrocarbons that are unique to either PS or each colorant. Volatiles detected in pure colorant (100%) were not detected in colored PS specimens. Amounts of PS solids migrating in 10 and 50% ethanol food simulating solvents were in a range of 0.0035 - 0.013% (w/w) based on polymer weight. Total polymer dissolution followed by precipitation of PS with methanol and analysis of the extract by HPLC-PDA showed the extraction of typical residuals from PS and other unidentified chemicals. Regardless of irradiation, addition of each colorant reduced concentrations of phenol, benzaldehyde, and acetophenone in the extracts. Irradiation increased the concentrations of other chemicals but had no effect on styrene. PR-0023-10/01 The uncertain association of Mycobacterium paratuberculosis (MpT) with Crohn's disease prompted this study to determine the incidence and concentration of MpT in raw milk. The objectives of this project were to determine the concentration of MpT in raw milk from commercial tankers and evaluate the adequacy of conventional pasteurization to inactivate MpT. Over the course of 11 months in 2002, MpT was found to be present in 32 out of 405 samples (8%). Of those, 30 were positive on Harold's egg yolk medium. The range of concentration of MpT was from .008 to <1.0 cfu per milliliter. In no case did the concentration ever exceed 1 cfu per milliliter. The number of MpT present in bulk tanker raw milk is important because this serves as the initial bioburden present before pasteurization. The effectiveness of conventional pasteurization time/temperature conditions for the inactivation of MpT in milk has been called into question, primarily by researchers in the United Kingdom where pasteurization treatment times have been extended to 25 seconds holding at temperature. The results from this study suggest that conventional pasteurization (72° for 15 seconds) should be adequate to control the bioburden of incoming raw tanker milk. PR-0024-10/01 The objectives of this project were 1) Development of sensors for detecting and quantitating biofilm formation in food processing equipment lines; and, 2) Use of sensors in testing the efficacy of sanitizers such as ozone, chlorine dioxide, peracetic acid and/or others used in controlling biofilms. A standard test method involving biofilm formation by various bacteria on various surfaces in a rotating disk reactor has been tested and validated. Attachment to various types of surfaces including stainless steel, polycarbonate, polyvinyl chloride and glass by various microorganisms under wet and dry conditions has been studied and compared. Using a biosensor (ChemArray Chip) manufactured by ST Microelectronics, bacteria attached to stainless steel, glass, polycarbonate, and polyvinyl chloride have been detected. Because the project was shortened by one year, objective 2 could not be completed. |
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