Methods for the Mycological Examination of Food

The desirability, indeed the necessity, for standardization of methods for the examination of foods for contaminant and spoilage mycoflora has been apparent for some time. The concept of a specialist workshop to address this problem was borne during conversations at the Gordon Research Conference on "Hicrobiological Safety of Foods" in Plymouth, New Hampshire, in July 1982. Discussions at that time resulted in an Organizing Committee of four, who became the Editors, and a unique format: all attendees would be expected to contribute and, in most cases, more than once; and papers in nearly all sessions would be presented as a set of data on a single topic, not as a complete research paper. Each session would be followed by general discussion, and then a panel would formulate recommendations for approval by a final plenary session. The idea for this format was derived from the famous "Kananaskis I" workshop on Hyphomycete taxonomy and terminology organized by Bryce Kendrick of the University of Waterloo, Ontario in 1969. Attendance would necessarily be limited to a small group of specialists in food mycology. The scope of the workshop developed from answers to questionnaires circulated to prospective participants. To generate new data which would allow valid comparisons to be drawn, intending participants were given a variety of topics as assignments and asked to bring information obtained to the workshop.

1: Sample Preparation.- Effect of Sample Size on Variance of Mold and Yeast Counts from Hard Cheese and Skim Milk Powder.- Evaluation of Blending, Stomaching and Shaking for the Mycological Analysis of Dried Foods.- Comparison of Stomaching Versus Blending in Sample Preparation for Mold Enumeration.- Evaluation of Blending, Stomaching and Shaking for Mold Counts in Flour.- Comparison of Fungal Counts on Foods Prepared by Blending or Stomaching.- Evaluation of Diluents Used in the Mycological Analysis of Dried Foods.- A Comparison Between Peptone and Ringer Solution with Polysorbitan Diluents on the Enumeration of Molds and Yeasts from Hard Cheese and Skim Milk Powder.- Comparison of Four Diluents for the Mycological Examination of Cereals.- Influence of the Addition of a Wetting Agent (Polysorbitan 80) in Diluent on Fungal Counts from Cereals.- Impromptu Contribution: Blending, Diluents and Sedimentation.- Effect of Incubating Plates Inverted or Upright When Enumerating Yeasts and Molds in Dry Seed-based Foods.- The Influence of Dilution on the Enumeration of Yeasts from Beverages.- Causes of Dilution Errors When Enumerating Molds in Foods.- Effect of Presoaking on Recovery of Fungi from Cereals and Cereal Products.- Optimization of Conditions for the Surface Disinfection of Sorghum and Sultanas Using Sodium Hypochlorite Solutions.- Comparison of Methods Used for Surface Disinfection of Food and Feed Commodities Before Mycological Analysis.- Dilution Plating Versus Direct Plating of Various Cereal Samples.- Comparison of Direct and Dilution Plating for Detecting Penicillium viridicatum in Barley Containing Ochratoxin.- Comparison of Pour Versus Surface Plating Techniques for Mold Enumeration.- Comparison of Spread and Pour Plate Methods for Enumerating Yeasts and Molds in Dry Foods Using DRBC Medium.- Comparison of Spread and Pour Plate Methods for Enumerating Yeasts and Molds in Dry Foods Using OGY Medium.- Discussion.- Recommendations.- 2: General Purpose Enumeration and Isolation Media.- Properties of the Ideal Fungal Enumeration Medium.- Principles for Media Evaluation.- Comparison of Various Media for the Enumeration of Yeasts and Molds in Food.- Comparison of Media for the Enumeration of Fungi from Dried Foods.- A Collaborative Exercise Comparing Media for Enumerating Fungi in Foods.- A Comparison of DRBC, RBC and MEA Media for the Enumeration of Molds and Yeasts in Pure Culture and in Foods.- A Comparison of DRBC, OGY and RBC Media for the Enumeration of Yeasts and Molds in Foods.- A Comparison of DG18 with RBC Media for the Enumeration of Molds in Pure Culture and Molds and Yeasts in Foods.- Comparison of a General Purpose Mycological Medium with a Selective Mycological Medium for Mold Enumeration.- Comparison of DRBC Medium with PDA Containing Antibiotics for Enumerating Fungi in Dried Food Ingredients.- A Comparison of DRBC and DG18 Media for Enumerating Molds and Yeasts in Cheddar Cheese and Skim Milk Powder.- Comparative Study of Media for the Detection and Enumeration of Molds and Yeasts.- Comparison of DG18 with PDA Medium Containing Antibiotics for Enumerating Fungi in Pasta Products.- Comparison of Five Media for the Enumeration of Molds in Cereals and Cereal Products.- Comparison of Media for Enumerating Yeasts and Molds in Dry Seed-based Foods.- Comparison of Media for the Enumeration of Molds in Flour.- Comparison of General Purpose Media for the Enumeration of Molds and Yeasts.- Merits and Shortcoming of DG18, OGY, OGGY and DRBC Media for the Examination of Raw Meats.- Discussion.- Recommendations.- 3: Selective Media and Procedures.- A Selective Medium for Rapid Detection of Aspergillus flavus.- Evaluation of Media for Simultaneously Enumerating Total Fungi and Aspergillus flavus and A. parasiticus in Peanuts, Corn Meal and Cowpeas.- Selective Medium for Penicillium viridicatum in Cereals.- Comparison of Selective Media and Direct or Dilution Plating for the Isolation of Toxigenic Fungi from Foods.- Comparison of Five Media for Enumeration of Mesophilic Mycoflora of Foods.- A Selective Medium for Fusarium Species.- Comparison of Enumeration Methods for Molds Growing in Flour Stored in Equilibrium with Relative Humidities Between 66 and 68%.- Enumeration of Xerophilic Yeasts in Apple Concentrate.- Comparison of Media for Counting Yeasts in High Fructose Syrup.- Techniques for the Enumeration of Heat Resistant Fungi.- Incidence, Properties and Detection of Heat Resistant Fungi.- Discussion.- Recommendations.- 4: Media for Yeasts and Consideration of Injured Cells.- Comparison of OGY with DRBC Medium for Enumerating Yeasts in Dry Food Products.- Effect of Diluent and Medium Water Activity on Recovery of Yeasts from High Sugar Coatings and Fillings.- Comparison of DRBC, OGY and PDA Media for Enumeration of Yeasts in Beverage Products.- Sensitivity and Precision of Methods for the Enumeration of Yeasts in Wine.- Consideration of Media for Enumerating Injured Fungi.- The “Phoenix Phenomenon” During Resuscitation of Fungi in Foods.- Discussion.- Recommendations.- 5: Significance of Fungal Populations on Foods (Baseline Counts).- Fundamentals of the Rational Use of Target Values (“Standards”) in the Microbiological Monitoring of Foods.- Baseline Counts of Yeasts and Molds in Foods in the Netherlands.- Fungal Flora and Counts on Foods.- Baseline Levels of Fungi in Food Ingredients, Beverages, Frozen Foods and Vegetables.- Baseline Counts for Yeasts in Beverages and Food Commodities.- Baseline Counts of Yeasts in Soft Drinks.- Baseline Counts for Sugar, High-Fructose Syrup and Honey.- Baseline Counts of Molds in Flour.- Baseline Counts for Wheat, Flour and Bran.- Baseline Counts of Molds in Dried Vegetables.- Baseline Count of Molds in Paprika.- Discussion.- Recommendations.- 6: Unacceptable Levels of Fungi.- Unacceptable Levels of Molds.- Unacceptable Levels of Potentially Toxigenic Fungi in Foods.- Unacceptable Levels of Specific Fungi.- Unacceptable Levels for Yeasts.- Unacceptable Levels of Yeasts in Bottled Wine.- Discussion.- Recommendations.- 7: New Techniques for Estimating Fungal Biomass in Foods.- New Techniques for Estimating Fungi in Foods.- New Techniques: Metabolic Measurements.- Comparison of a Plate-MPN Technique with Surface Plate Count for Mold Enumeration.- Impedimetric Estimation of Molds.- Modern Detection Methods for Food Spoilage Fungi.- Discussion.- Recommendations.- 8: Taxonomic Schemes for Foodborne Fungi.- Compilation of Foodborne Filamentous Fungi.- Aids in the Identification of Important Foodborne Species of Filamentous Fungi.- A Simplified Scheme for the Identification of Yeasts.- Discussion.- APPENDIX I: Formulae for Mycological Media.- Participants and Attendees.- Author Index.