More Laboratory Papers and Exhibits
Last month, I previewed some of the many technical papers and instrumentation and quality assurance exhibits from the IFT Annual Meeting & Food Expo to be held in Anaheim, Calif., June 15–19, 2002. In this issue, I will preview additional selected papers and exhibits for which we received information by the deadline date.
Immunochemical analysis of various food ingredients for detectable gluten content will be dicussed by A.L. Lardizabal, Food Allergy Research and Resource Program, University of Nebraska–Lincoln, Lincoln. Unidentified wheat presence in the food supply presents a serious health risk to individuals who suffer from either true wheat allergy or celiac sprue. Many foods are perceived by celiac- and wheat-allergic persons as containing wheat gluten or proteins, which can lead to a more restricted diet than necessary. The objective of this research was to determine the presence of wheat gluten in non–wheat-containing, “wheat-free,” “gluten-free” foods and ingredients. A commercially available wheat gluten immunoassay kit (lower detection limit was 10 ppm gluten) was used to test samples. The study found that caution must be taken when eating food products labeled “wheat-free” or “gluten free,” as some can contain appreciable amounts of wheat. Paper 46I-16, Monday morning
Friction of food powders may be measured with a new flowability index developed by P. Juliano of Washington State University. Food powders represent a wide range of particulate materials utilized in the food industry. They differ in their chemical composition and physical characteristics. Flowability is the ease with which a powder flows through a chute or hopper. It can be expressed by indices such as the flow factor and cohesiveness determined by shear tests. Accurate measurement of flowability indices has, however, remained a problem.
The objective of this research was is to propose a new method to relate flowability index of powders to conventional flowability parameters. The method recognizes that the total shear strength of a particulate material during shearing is composed of friction and interlocking. The interlocking strength results for the volumetric changes during shearing. The frictional strength of powders can therefore be determined by accounting for interlocking. The proposed method can be used to find flowability of food powders with different compositions. It avoids the ambiguity in the selection normal stress at which powders flow freely. Paper 91C-14, Tuesday afternoon
Use of bioluminescent organisms for shelf life testing will be discussed by N.G. Bright of Purdue University. Genetically engineered bioluminescent bacteria offer an alternative approach for measuring biomass due to the correlation of bioluminescence and cell number. The researchers hypothesize that surrogate bioluminescence organisms can be utilized in shelf life studies by examining the increase in bioluminescence as an indirect measure of increasing biomass. The objective of this study was to develop an alternative assay to plate counting for shelf-life studies utilizing bioluminescent bacteria as challenge organisms. Results demonstrated an increase in bioluminescence with increasing temperatures, showing increased biomass with temperature abuse. Thus, bioluminescence can be used to replace classical plate count methods to provide an assay that is less labor and material intensive. Paper 100A-31, Wednesday morning
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New rapid method for monitoring coliforms in foods will be described by D.H. Kang of Washington State University. The conventional plating method on VRBA is the most popular method for monitoring coliforms in foods. However, this method requires about 24 hr incubation. So, a more rapid, simple, economical method is needed to monitor coliforms in foods. The purpose of this study was to develop a simplified rapid cultivation method utilizing the gelling reaction of alginate with calcium chloride to produce a semi-solid medium, and to compare this new procedure with the conventional plating method. The researchers found that the alginate method is a rapid, simple, accurate, and economical way to monitor and estimate total coliforms in milk. Paper 100A-17, Wednesday morning
Gelatin gels and the relationship between sensory hardness and cohesiveness perception and their instrumental measurements will be described by M.L. Finney of the University of Arkansas. The objectives of this study were to develop standardized gels of known rheological properties, document how rheological properties affect biting, and assess correlations between fundamental and imitative rheological tests and perceived sensory modalities. Fourteen gels of various gelatin and glycerol concentrations were produced to represent a broad spectrum of sensory intensities. The researchers found that all individuals do not manipulate food products in the same manner. This should be a consideration in designing imitative instrumental tests. Session 85-3, Tuesday afternoon
Magnetic resonance detection of bacterial contamination in packaged shelf-stable, low-acid foods will be discussed by M. Pascall of the Food and Drug Administration, National Center for Food Safety & Technology. Many processors of shelf-stable food will store products for a week or more before shipment to ensure the detection of spoiled and contaminated packages using statistical sampling and visual inspection. Such methods cannot prevent occasional defective units from being shipped. Thus, an automated system that can nondestructively test all packages produced would be a major advantage.
The objective of this study was to evaluate magnetic resonance (MR) as a non-destructive method for bacterial detection in processed packaged foods. MR relaxation (T2) times were correlated with the growth of Bacillus stearothermophilus and Bacillus subtilis in commercial soymilk packaged in 355-mL polymeric trays. These results were compared with viscosity and pH changes in the soymilk caused by these organisms. Results showed that MR has the potential to be used for nondestructive identification of contaminated or underprocessed foods in polymeric packages. Paper 87-3, Tuesday afternoon
Evaluation of enrichment times required for the detection of Escherichia coli O157 in ground beef using the Pathigen® E. coli O157 test will be discussed by C.C. Young of IGEN International, Inc., Gaithersburg, Md. The increased sensitivity of newly developed methods for the detection of E. coli O157 has reduced enrichment times to as little as 8 hr. The development of more-sensitive methods will allow enrichment times to be shortened further. The researchers investigated the ability of their test to detect the presence of E. coli O157 in ground beef compared against the FSIS plating method employing bead extraction and plating onto Rainbow® Agar. The results indicated that the test with a 6-hr enrichment time is more sensitive than the FSIS plating method. Paper 97-11, Wednesday morning
Guidelines for testing in government laboratories are based on standards found in the ISO/IEC Guide 25. J.W. Ho of USDA’s Agricultural Marketing Service will speak on how the USDA/AMS Science and Technology (S&T) Programs provide laboratory testing services in support of commodity procurement programs and the agricultural community. The S&T laboratories operate under a user-fee program to perform chemical, microbiological, and physical analyses on various food products and commodities for the federal, state, and private sectors. A wide variety of foods are available to consumers as a consequence of the increase in international trade. Domestic and foreign buyers frequently place specifications in their purchase contracts that may require laboratory testing. To ensure the reliability of laboratory results, the test data must be generated by a competent laboratory that can be assessed via an accreditation process.
One of the recognized international standards for laboratory accreditation is ISO/IEC Guide 25 (which is being replaced by ISO/IEC 17025). The author will discuss how the S&T’s Blakely, Ga., aflatoxin and proximate laboratory, has attained the desired accreditation. This activity serves as a template to facilitate the accreditation of other S&T laboratories. Session 30H-5, Sunday afternoon
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PCR detection of Morganella morganii and its occurrence in fish and processing plants will be the topic of a presentation by H. An of Auburn University. With the implementation of HACCP under FDA’s regulation, monitoring histamine in fish is a critical task in seafood industry. M. morganii is the main contributor to histamine formation in fish because of its prevalence and ability to produce high level of histamine. Its detection has relied on conventional culture methods, despite their low sensitivity and time requirements.
The researchers developed a molecular technique, PCR assay, and found the sources of M. morganii in fish and processing plant. The organism was detected on the surfaces of conveyer belt and plastic crate that came in contact with fish during processing. Direct detection without the need for isolation of pure culture was achieved by using the PCR assay developed. M. morganii originates from the gill and skin of fish. It is possible that it may cross-contaminate during handling of fish in processing plants and restaurants. For a better control of histamine formation, introduction and contamination of M. morganii in seafood products should be avoided by practicing a good hygiene at each handling step. Paper 97-5, Wednesday morning
Monitoring residual solvents in foods and food contact packaging by gas chromatography will be discussed by R.E. Wittrig of Restek Corp. The research team developed chromatographic procedures for monitoring residual solvents in food and food contact packaging materials. Ideally, they would like to be able to analyze all of the volatile compounds in a single chromatographic run, using either a flame ionization or a mass selective detector. Because of the wide range of polarities and volatilities displayed by potential residual solvents in foods, a specialized stationary phase containing a mixture of functional groups was selected. The results from the analyses of a variety of food materials and food containers will be presented. The materials can be easily sampled using a dynamic headspace purge-and-trap technique. Session 30H, Sunday afternoon
Analytical Balances in the new GX series may be used in food laboratory and quality assurance situations. The balances combine magnetic force restoration and single-point parallelogram load-sensing technologies. Magnetic force restoration is said to ensure high resolution and sensitivity in light-capacity weighing, while single point parallelogram technology ensures durability and speed. The company claims that combining these technologies eliminates all but three of the traditional 11 flexures found in traditional balances. Subsequently, temperature induced drift is significantly minimized. A&D Weighing, Inc., 1555 McCandless Dr., Milpitas, CA 95035 (phone 408-263-5333; www.andweighing.com), Booth 1000
Environmentally controlled equipment for the educational, biomedical, pharmaceutical, clinical and industrial research market is being offered by Thermo Forma. Product lines include cell culture incubators, ultra-low temperature freezers, biological safety cabinets, orbital shakers, and cryopreservation equipment. The incubators are designed for foodservice laboratory applications. Thermo Forma, P.O. Box 649, Marietta, OH 45750 (phone 800-848-3080; fax 740-374-1817 www.thermo.com), Booth 2007
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High-temperature refractometers may be used for measuring refractive index in a variety of food products, such as high-fructose corn syrups and oils. The J Series of refractometers has been extended with the HT option, allowing for high-temperature measurement. These models expand the J Series electronic heating and cooling capability to reach 70ºC. The electronic temperature control in heating at high temperatures means that the water bath and assorted tubing for water circulation may be eliminated. Rudolph Research Analytical, 354 Rte. 206, Flanders, N.J. 07836 (phone 973-584-1558; fax 973-584-5440), Booth 8923
Rheological measurements of foods may be made with the AR 2000 Advanced Rheometer. The company claims that it is the most versatile research-grade rheometer commercially available for rapid characterization of mobile and viscous liquids, gels, pastes, slurries, solids (in torsion), and molten polymers. The instrument features controlled stress and controlled rate operation; a wide torque range with very low inertia; maximum angular velocity; and a choice of temperature-control options. TA Instruments, Inc., 109 Lukens Dr., New Castle, DE 19720 (phone 302-427-4000; fax 302-427-4001; e-mail [email protected]), Booth 8601
HPLC instrumentation for food analysis applications will be exhibited by Waters Corp. The Breeze HPLC system is said to offer high performance, reliability, and affordability in one comprehensive package. Waters Corp., 34 Maple St., Milford, MA 01757 (phone 508-478-2000; 800-252-4752; fax 508-872-1990; www.waters.com), Booth 1700
NIR instruments may be used to measure moisture, protein, and carbohydrate content in grain and other food products. Improved versions of the ZX-550 Portable NIR Food/Dairy Analyzer and the ZX-880 Lab Grade NIR Food/Dairy Analyzer will be exhibited. Zeltex, Inc., 130 Western Maryland Pkwy., Hagerstown, MD 11743 (phone 800-732-1950; fax 301-733-9398; www.zeltex.com), Booth 6231
Environmental surface sampling bags are designed for use on work areas, equipment, animal carcasses, and other places where testing for Listeria, Salmonella, and other foodborne pathogens is required. The special sterilized sponge is free of bactericides and has been tested to be non-inhibitory. It measures 1.5 in x 3 in when wet. After the sample has been collected and the sponge returned to the bag, it can be sent to a lab for testing. Nasco, 901 Janesville Ave., Box 901, Ft. Atkinson, WI 53538-0901 (phone 920-563-2446; fax 920-563-8296), Booth 7504
by JAMES GIESE