9/9/2016 Food Learning Objectives 1.Differentiate among the various microbiological criteria in foods 2.Identify national and international agencies involved in Chapter 6 AN INTRODUCTION establishing microbiological criteria 3. Recognize how indicator organismsare used in Indicator microbiological criteria Microorganisms and 4.Understand why some sampling plans are more stringent than others Microbiological 5.Identify organisms and types of foods for which zero Criteria tolerance has been established 6.ro Microbiological Criteria in Foods Purpose of Microbiological Criteria in Foods Microbiological criteria are tools used in To ensure that a product has been assessing the safety and quality of foods produced under sanitary conditions and A microbiological criterion defines the is microbiologically safe to consume acceptability of a product or a food lot, Microbes are found in most raw and based on the absence or presence,or finished food products number of microorganisms including Certain bacteria,even we're not parasites,and/or quantity of their pathogens,may be safe ALL BAD toxins/metabolites,per unit(s)of mass, volume,area or lot in food,depending on the food product
9/9/2016 1 Chapter 6 Indicator Microorganisms and Microbiological Criteria Learning Objectives 1. Differentiate among the various microbiological criteria in foods 2. Identify national and international agencies involved in establishing microbiological criteria 3. Recognize how indicator organisms are used in microbiological criteria 4. Understand why some sampling plans are more stringent than others 5. Identify organisms and types of foods for which zero tolerance has been established 6. Identify and list steps required to manage microbiological hazards in foods Microbiological Criteria in Foods • Microbiological criteria are tools used in assessing the safety and quality of foods • A microbiological criterion defines the acceptability of a product or a food lot, based on the absence or presence, or number of microorganisms including parasites, and/or quantity of their toxins/metabolites, per unit(s) of mass, volume, area or lot Purpose of Microbiological Criteria in Foods To ensure that a product has been produced under sanitary conditions and is microbiologically safe to consume • Microbes are found in most raw and finished food products • Certain bacteria, even pathogens, may be safe in food, depending on the food product
9/9/2016 Purpose of Microbiological Criteria in Foods Microbiological criteria are used to assess: To distinguish between acceptable and unacceptable 1.Safety of food products or food-processing practices 2.Adherence to good manufacturing Numbers and types of microbes associated with practices (GMPs) foods may be used to judge safety and quality 3.Shelf life of perishable foods Safety-absence,presence,or level of pathogens and their toxins and the expected control or 4.Suitability of a food or ingredient for destruction of them a particular purpose Spoilage-level of spoilage microbes and their control measures reflects food quality Microbiological criteria ensure the safety Indicator organisms may be used to assess and quality of foods microbial quality or safety Assessing a Need for Microbiological Criteria Microbiological Criteria Include 1.Evidence of a health hazard based on 1.A statement identifying the food and the epidemiological data or a hazard analysis microbe and/or toxins of concern 2.Nature of the food's normal microbial makeup 2.Lab methods for detection and 3.Ability of the food to support microbial growth quantification of each microbe of concern 4.Effect of processing on the microflora of the food 3.Sampling plan 5.Potential for microbial contamination and/or 4.Microbiological limits for the food growth during processing,handling,storage,and distribution 5.Number of samples required to confirm these limits 6.Spoilage potential and GMPs 2
9/9/2016 2 To distinguish between acceptable and unacceptable products or food-processing practices • Numbers and types of microbes associated with foods may be used to judge safety and quality • Safety - absence, presence, or level of pathogens and their toxins and the expected control or destruction of them • Spoilage – level of spoilage microbes and their control measures reflects food quality • Indicator organisms may be used to assess microbial quality or safety Purpose of Microbiological Criteria in Foods Microbiological criteria are used to assess: 1. Safety of food 2. Adherence to good manufacturing practices (GMPs) 3. Shelf life of perishable foods 4. Suitability of a food or ingredient for a particular purpose Microbiological criteria ensure the safety and quality of foods Assessing a Need for Microbiological Criteria 1. Evidence of a health hazard based on epidemiological data or a hazard analysis 2. Nature of the food’s normal microbial makeup 3. Ability of the food to support microbial growth 4. Effect of processing on the microflora of the food 5. Potential for microbial contamination and/or growth during processing, handling, storage, and distribution 6. Spoilage potential and GMPs Microbiological Criteria Include 1. A statement identifying the food and the microbe and/or toxins of concern 2. Lab methods for detection and quantification of each microbe of concern 3. Sampling plan 4. Microbiological limits for the food 5. Number of samples required to confirm these limits
9/9/2016 Mandatory or Advisory Criteria 3 Categories of Criteria Mandatory criterion-may not be ·Mandatory exceeded Failure to comply is a violation sub ject to Food that does not meet the specified enforcement policy limit is required to be rejected, Guideline:used by the food industry or regulatory destroyed,reprocessed,or diverted agency to monitor a manufacturing practice Serve as an alert mechanism Advisory criterion-permits acceptable Assess processing efficiency judgments to be made ·Advisory Serves as an alert to deficiencies in Specifications:used as a purchase require processing,distribution,storage,or marketing Mandatory or advisory Who Establishes Microbiological Criteria? .Various scientific organizations develop general 1981-Codex Alimentarius program principles for the application of microbiological criteria formulated General Principles for the Those that have most affected the food industry Establishment and Application of Microbiological Criteria r90 International Food Standards Program .1984-regulatory agencies requested 2.International Commission on Microbiological formulation of general principles for the Specifications for Foods application of microbiological criteria to 3.US National Academy of Sciences food and food ingredients 4.US National Advisory Committee on Microbiological Criteria for Foods
9/9/2016 3 Mandatory or Advisory Criteria Mandatory criterion – may not be exceeded • Food that does not meet the specified limit is required to be rejected, destroyed, reprocessed, or diverted Advisory criterion – permits acceptable judgments to be made • Serves as an alert to deficiencies in processing, distribution, storage, or marketing 3 Categories of Criteria Standard: part of a law, ordinance, or administrative regulation • Mandatory • Failure to comply is a violation subject to enforcement policy Guideline: used by the food industry or regulatory agency to monitor a manufacturing practice • Serve as an alert mechanism • Assess processing efficiency • Advisory Specifications: used as a purchase requirement whereby conformance becomes a condition of purchase between buyer and vendor • Mandatory or advisory Who Establishes Microbiological Criteria? • Various scientific organizations develop general principles for the application of microbiological criteria • Those that have most affected the food industry 1. Joint Food and Agricultural Organization and World Health Organization Codex Alimentarius International Food Standards Program 2. International Commission on Microbiological Specifications for Foods 3. US National Academy of Sciences 4. US National Advisory Committee on Microbiological Criteria for Foods • 1981 – Codex Alimentarius program formulated General Principles for the Establishment and Application of Microbiological Criteria • 1984 – regulatory agencies requested formulation of general principles for the application of microbiological criteria to food and food ingredients
9/9/2016 Codex Alimentarius Sampling Plans Includes both sampling procedure and decision criteria Collection of internationally recognized standards,codes of practice,quidelines, To examine food for microbes a representative sample is examined by defined methods and other recommendations relating to Impractical to examine an entire food lot foods,food production,and food safety (quantity of product produced,handled,and Standards for all foods in the form in stored within a limited time under uniform conditions) which they are delivered to the consumer -Statistical concepts of population probability processed,semi-processed,raw and sampling are used to determine the number WHO recommends its use to make all and size of sample units needed to provide standards similar conclusions Inferior lots are rejected Simple Example Types of Sampling Plans 10 samples tested for a microbe Two categories based on distribution of microbes in food Variables sampling plan The more samples examined,the -used if microbes have an even distribution in the food -analytical sample represents the entire lot(milk) Decision criteria lower the risk of making an incorrect decision about a lot quality maximum Attributes sampling plan (used more frequently) allowable positive Time-consuming and costly -used if microbes are not distributed evenly within the Compromise is made between the food samples is 2 number of samples and the risk -analytical samples may vary greatly -used if the microbe is present at low numbers used for food at ports of entry as little is known on how If >2 samples are If 2 or less is the food was processed positive,then the positive,then the -used to monitor performance relative to GMPs lot is rejected lot is accepted -NOT used if there is no defined lot or when random sampling is not possible 4
9/9/2016 4 Codex Alimentarius • Collection of internationally recognized standards, codes of practice, guidelines, and other recommendations relating to foods, food production, and food safety • Standards for all foods in the form in which they are delivered to the consumer – processed, semi-processed, raw • WHO recommends its use to make all standards similar Sampling Plans • Includes both sampling procedure and decision criteria • To examine food for microbes a representative sample is examined by defined methods - Impractical to examine an entire food lot (quantity of product produced, handled, and stored within a limited time under uniform conditions) - Statistical concepts of population probability and sampling are used to determine the number and size of sample units needed to provide conclusions - Inferior lots are rejected 10 samples tested for a microbe If >2 samples are positive, then the lot is rejected If 2 or less is positive, then the lot is accepted Decision criteria maximum allowable positive samples is 2 Simple Example - The more samples examined, the lower the risk of making an incorrect decision about a lot quality - Time-consuming and costly - Compromise is made between the number of samples and the risk Types of Sampling Plans Two categories based on distribution of microbes in food • Variables sampling plan - used if microbes have an even distribution in the food - analytical sample represents the entire lot (milk) • Attributes sampling plan (used more frequently) - used if microbes are not distributed evenly within the food - analytical samples may vary greatly - used if the microbe is present at low numbers - used for food at ports of entry as little is known on how the food was processed - used to monitor performance relative to GMPs - NOT used if there is no defined lot or when random sampling is not possible
9/9/2016 Two-Class Sampling Plan Two-Class Sampling Plan Almost exclusively used for pathogens-preferred when the organism of concern is not permitted in Decision criterion is based on food sample number of sample units-n Assigns the microbial concentration in the food to an -maximum allowable units with attribute class depending on whether it is above or unsatisfactory results-c below a preset concentration limit of the microbe(m) -microbiological limit-m c=max number of allowable unsatisfactory units accept all samples are sm accept all samples are s m lot lot eioteiese sc of n samples are >m s 2 of 5 samples are>m >c ofn samples are >m reject lot >2 of 5 samples are>m reject lot Three Class Sampling Plan Two microbiological limits are considered ·Hygiene indicators Attributes Plans m reflects the upper limit of GMP Two-class and Three-class ·2 marks the beyond which the level of contamination is hazar is or unacceptable Separates acceptable lots from marginally acceptable lots between m and M limits all samples are sm accept lot accept lo reject lot any sample is≥M eject lot Log countig 5
9/9/2016 5 n samples from the lot are tested all samples are ≤ m accept lot ≤ c of n samples are > m accept lot > c of n samples are > m reject lot Two-Class Sampling Plan • Almost exclusively used for pathogens - preferred when the organism of concern is not permitted in food sample • Assigns the microbial concentration in the food to an attribute class depending on whether it is above or below a preset concentration limit of the microbe (m) • c = max number of allowable unsatisfactory units 5 samples from the lot are tested all samples are ≤ m accept lot ≤ 2 of 5 samples are > m accept lot > 2 of 5 samples are > m reject lot Two-Class Sampling Plan • Decision criterion is based on - number of sample units – n - maximum allowable units with unsatisfactory results – c - microbiological limit - m Stringency is adjusted by changing the value(s) of c and/or n Three Class Sampling Plan Two microbiological limits are considered • Hygiene indicators • m reflects the upper limit of GMP • M marks the limit beyond which the level of contamination is hazardous or unacceptable • Separates acceptable lots from marginally acceptable lots between m and M limits n samples from the lot are tested all samples are ≤m accept lot ≤ c of n samples are within > m and ≤ M accept lot > c of n samples are within > m and ≤ M reject lot any sample is ≥ M reject lot Stringency is adjusted by changing the value(s) of c and/or n acceptable unacceptable acceptable marginally acceptable unacceptable Attributes Plans Two-class and Three-class
9/9/2016 Establishing Limits GMPs may be expected to produce food Microbiological limits represent the level above with a better microbiological profile than which action is required those produced under poor conditions Limits are based on knowledge of GMPs always correlate with low microbial the raw material counts effect of processing,handling and storage end use of the product Use of poor-quality materials,improper likelihood of uneven distribution of microbes handling or unsanitary conditions may variability of the analytical procedure yield high microbial counts despite GMPs risk associated with the microbes conditions of food handling and consumption Limits include sample weight analyzed,method reference,and confidence limits of the method Quantitative Risk Assessment Indicator Organisms of Microbiological Quality Techniques are used to determine scientifically the probability of occurrence and severity of Provide simple reliable and rapid human exposure to foodborne hazards information about process failure Relatively new to food safety microbiology post-process contamination The process consists of contamination from the environment hazard identification level of hygiene during food hazard characterization processing and storage exposure assessment Used in microbiological criteria risk characterization Suggest a microbial hazard 6
9/9/2016 6 Establishing Limits • Microbiological limits represent the level above which action is required • Limits are based on knowledge of - the raw material - effect of processing, handling and storage - end use of the product - likelihood of uneven distribution of microbes - variability of the analytical procedure - risk associated with the microbes - conditions of food handling and consumption • Limits include sample weight analyzed, method reference, and confidence limits of the method • GMPs may be expected to produce food with a better microbiological profile than those produced under poor conditions • GMPs always correlate with low microbial counts • Use of poor-quality materials, improper handling or unsanitary conditions may yield high microbial counts despite GMPs Quantitative Risk Assessment • Techniques are used to determine scientifically the probability of occurrence and severity of human exposure to foodborne hazards • Relatively new to food safety microbiology • The process consists of - hazard identification - hazard characterization - exposure assessment - risk characterization Indicator Organisms of Microbiological Quality • Provide simple, reliable, and rapid information about - process failure - post-process contamination - contamination from the environment - level of hygiene during food processing and storage • Used in microbiological criteria • Suggest a microbial hazard
9/9/2016 Indicators Must Meet the Following E.colias indicator of fecal contamination Criteria: present in mammalian feces Present and detectable in all foods whose at high concentrations quality is assessed survives in water for weeks Growth and numbers have a direct negative meets all the criteria correlation with product quality defining total coliforms Easily detected and enumerated and fecal coliforms Clearly distinguishable from other organisms distinguished from other coliforms by lack Enumerable in a short period of time,ideally of urease and presence of B-glucuronidase within one working day enzymes Growth not inhibited by other microbes indicator of possible pathogens Primary Spoilage Indicators Total Microbial Count in Food as a Table61 Organisms highly coraed with product quiy Microbiological Indicator Organism(s) Product(s) Fresh cider Loss of quality may involve more than Bread douwh one microbe ·Aerobic Plate Count Hard cheese Flat-sour spores Canned vegetables -used to determine the total number Lactic acid bacteria Beers,wines Lactos lactis Raw milk (refrigerated of microbes in a food product Leiecouostoc meserleroides Sugar (during refining) -modify incubation environment and Pectinatus eevisiphilus Beers Butter medium to screen for groups of Yeasts microbes
9/9/2016 7 Indicators Must Meet the Following Criteria: • Present and detectable in all foods whose quality is assessed • Growth and numbers have a direct negative correlation with product quality • Easily detected and enumerated • Clearly distinguishable from other organisms • Enumerable in a short period of time, ideally within one working day • Growth not inhibited by other microbes E. coli as indicator of fecal contamination • present in mammalian feces at high concentrations • survives in water for weeks • meets all the criteria defining total coliforms and fecal coliforms • distinguished from other coliforms by lack of urease and presence of B-glucuronidase enzymes • indicator of possible pathogens Primary Spoilage Indicators Total Microbial Count in Food as a Microbiological Indicator • Loss of quality may involve more than one microbe • Aerobic Plate Count - used to determine the total ? number of microbes in a food product - modify incubation environment and medium to screen for groups of microbes
9/9/2016 ·Aerobic Plate Count Examples for when a bacterial count is used as an indicator in microbiological criteria used to assess product quality when Thermophilic spores in sugar and spices monitoring: intended for use in the canning industry 1.foods that comply with standards sugar that is not suitable for use in or guidelines set by regulatory low-acid canning may be diverted for agencies other uses 2.foods that comply with purchase Refrigerated perishable foods,such as milk,meat,poultry,and fish specifications condition of the equipment and 3.adherence to GMPs utensils time-temperature profile storage and distribution of food Limitations of Aerobic Plate Counts Limitations of Aerobic Plate Counts (cont'd) 1.APCs measure only live cells 4.Only aerobic microbes are counted -a grossly spoiled food may have a low cell 5.Bacterial type is not known count 6.Media may not support growth of all microbes 2.APCs are of little value in assessing sensory quality 7.Colonies may be too small to count high microbial counts are required for 8.Eye strain/human error sensory-quality loss 9.Food particles and bacteria may look alike 3.Biochemical activities vary greatly Interpretation of APCs of a food requires between bacteria knowledge of the expected microbial quality loss may occur at low total counts population at the point of sample collection 8
9/9/2016 8 • Aerobic Plate Count - used to assess product quality when monitoring: 1. foods that comply with standards or guidelines set by regulatory agencies 2. foods that comply with purchase specifications 3. adherence to GMPs Examples for when a bacterial count is used as an indicator in microbiological criteria • Thermophilic spores in sugar and spices intended for use in the canning industry - sugar that is not suitable for use in low-acid canning may be diverted for other uses • Refrigerated perishable foods, such as milk, meat, poultry, and fish - condition of the equipment and utensils - time-temperature profile storage and distribution of food Limitations of Aerobic Plate Counts 1. APCs measure only live cells - a grossly spoiled food may have a low cell count 2. APCs are of little value in assessing sensory quality - high microbial counts are required for sensory-quality loss 3. Biochemical activities vary greatly between bacteria - quality loss may occur at low total counts Limitations of Aerobic Plate Counts (cont’d) 4. Only aerobic microbes are counted 5. Bacterial type is not known 6. Media may not support growth of all microbes 7. Colonies may be too small to count 8. Eye strain / human error 9. Food particles and bacteria may look alike Interpretation of APCs of a food requires knowledge of the expected microbial population at the point of sample collection
9/9/2016 Direct Microscopic Count as a Other Methods to Indicate Microbiological Indicator the Quality of Foods Estimates both viable and non-viable cells Howard Mold Count in samples containing a large number of Used to detect molds and yeasts in canned fruit and microbes >105 CFU/ml tomato products Used to evaluate sanitary conditions of processing Has limited value as part of microbiological machinery in vegetable canneries criteria for quality issues Yeast and mold grow under conditions that are less- favorable for bacteria Use is restricted to a few products,raw milk,dried milk,liquid and frozen eggs,and Problem for fermented dairy products,fruits,fruit beverages,and soft drinks dried eggs Counts are part of microbiological standards for various dairy products Metabolic Products as Indicators for Indicators of Foodborne Pathogens Microbiological Criteria and Toxins Metabolic products are produced by All foods do not require microbes associated with food microbiological criteria A metabolic product may be correlated Microbiological criteria are used if with product quality loss a food is repeatedly implicated as vehicle in foodborne disease Example:sensory evaluation of shrimp outbreaks examination of changes in appearance. Early 20th century,safety of milk color,texture,and odor to determine was improved due to setting of deterioration quality microbiological criteria and the development of safer pasteurization methods
9/9/2016 9 Direct Microscopic Count as a Microbiological Indicator • Estimates both viable and non-viable cells in samples containing a large number of microbes > 105 CFU/ml • Has limited value as part of microbiological criteria for quality issues • Use is restricted to a few products, raw milk, dried milk, liquid and frozen eggs, and dried eggs Other Methods to Indicate the Quality of Foods Howard Mold Count • Used to detect molds and yeasts in canned fruit and tomato products • Used to evaluate sanitary conditions of processing machinery in vegetable canneries Yeast and mold grow under conditions that are lessfavorable for bacteria Problem for fermented dairy products, fruits, fruit beverages, and soft drinks Counts are part of microbiological standards for various dairy products Metabolic Products as Indicators for Microbiological Criteria • Metabolic products are produced by microbes associated with food • A metabolic product may be correlated with product quality loss • Example: sensory evaluation of shrimp - examination of changes in appearance, color, texture, and odor to determine deterioration quality Indicators of Foodborne Pathogens and Toxins All foods do not require microbiological criteria Microbiological criteria are used if a food is repeatedly implicated as a vehicle in foodborne disease outbreaks • Early 20th century, safety of milk was improved due to setting of microbiological criteria and the development of safer pasteurization methods
9/9/2016 Distribution of illnesses by food type in 1,565 foodborne outbreaks caused by a single food Food processors may alter the intrinsic or type and reported to CDC 2003-2008. extrinsic properties of a food To ensure growth inhibition of Staphylococcus aureus in cheese and fermented sausage production,a lactic acid starter culture is added to produce acid to inhibit harmful levels of 5.aureus As a critical control point, the rate of acid production is measured to ensure quality control Consumers are often overlooked as variables in Low level of a pathogen in a food product may or microbiological risk assessment may not be a health risk Rigid microbiological requirements may be Some microbes have a low infectious dose and needed for food consumed by susceptible their presence alone predicts a health risk consumers Their growth is not a concern but their -Infants and young children survival in the food is -Elderly HOW SAFE Foods that prevent survival of pathogens may -Immunocompromised IS YOUR FOOD? NOT be candidates for microbiological criteria >AIDS patients @国@绒 related to safety >Cancer patients >Transplant patients From farm to plate, -Pregnant women Malnourished 10
9/9/2016 10 Distribution of illnesses by food type in 1,565 foodborne outbreaks caused by a single food type and reported to CDC 2003-2008. Food processors may alter the intrinsic or extrinsic properties of a food • To ensure growth inhibition of Staphylococcus aureus in cheese and fermented sausage production, a lactic acid starter culture is added to produce acid to inhibit harmful levels of S. aureus • As a critical control point, the rate of acid production is measured to ensure quality control Low level of a pathogen in a food product may or may not be a health risk • Some microbes have a low infectious dose and their presence alone predicts a health risk - Their growth is not a concern but their survival in the food is • Foods that prevent survival of pathogens may NOT be candidates for microbiological criteria related to safety Consumers are often overlooked as variables in microbiological risk assessment • Rigid microbiological requirements may be needed for food consumed by susceptible consumers - Infants and young children - Elderly - Immunocompromised AIDS patients Cancer patients Transplant patients - Pregnant women - Malnourished