food microbiology

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food microbiology создатель Mind Map: food microbiology

1. single cell protien

1.1. also called

1.1.1. Noval food or minifood scp : dried cells of microorganism.

1.2. used can be plant biomass and organic biomass that serve as the protein source and the substrate that is biomass.

1.3. A list of the micro-organisms used for SCP production

1.3.1. bacteria such as :• Lactobacillus fungi such as: • Aspergillus nigeralgae such as : • Chlorella pyrenoidosa yeast such as :• Saccharomyces cerevisae Production of SCP requires micro-organisms.

1.4. SCP they are used as aimal feed and for human feed as protien supplement

1.5. SCP can be subdivided into three categories

1.5.1. 1-high energy sources

1.5.2. 2-different wastes

1.5.3. 3-plant resources

1.6. Biomass also plays a very important role in the production of SCP

1.6.1. Biomass also plays a very important role in the production of SCP

1.7. Production of SCP requires micro-organisms


1.8.1. Illumination time

1.8.2. ph

1.8.3. Temperature

1.8.4. Suitable strains

1.8.5. Agitation

1.8.6. Sterile conditions


1.9.1. Selection of suitable strain Microbe selected shouldn’t produce toxicity in its biomass. It should not be harmful for a consumer to consume Substrate should be cheap, effective, allow favorable growth and ease of isolation. Selected microbe should produce a large quantity of protein.

1.9.2. Fermentation done under sterilized conditions. Controlled fed-batch cultures are used for the fermentation of microbes Is done in a large chamber either of glass or stainless steel called “Fermentor”

1.9.3. Harvesting Decantation is a process for the separation of mixtures, by removing a layer of liquid, generally on from which a precipitate has settled

1.9.4. Post harvest treatment


1.10. applications

1.10.1. 1. As protein supplemented food

1.10.2. 2. As health food

1.10.3. 3. In therapeutic and natural medicines

1.10.4. 4. Poultry and cattle feed.

2. probiotics and prebiotic

2.1. Characteristics of a good probiotic

2.1.1. The culture should exert a positive effect on the host.

2.1.2. The culture microorganisms should neither be pathogenic nor toxic to the host.

2.1.3. The culture should possess high survival rate and multiply faster in the digestive

2.2. action of probiotics

2.2.1. Production of lactic acid by hydrolysis of milk lactose by Probiotics Competitive exclusion

2.2.2. -Acid production and lowering of pH

2.2.3. Excretion of antibiotic like substances

2.2.4. Microbial enzymes are beneficial to the host because they increase the digestion of nutrients especially in the small intestine

2.2.5. This DE conjugation of bile acids by the probiotic culture enhances its anti-microbial nature and the production of anti-microbial compounds

2.2.6. Ammonia production

2.2.7. The anti-cholsteromic activity of lactic acid bacteria is expressed by 3 ways Anticholesterolemic effects By inhibiting cholesterol synthesis By inhibiting intestinal absorption Deconjugation of bile salts could lead to a reduction in serum cholesterol either By deconjugation of bile salts

2.2.8. Antimutagenic and anticarcinogenic activity

2.2.9. Mechanism of cholesterol assimilation by probiotics Direct Inhibiting the de novo synthesis of cholestero Decreasing the intestinal absorption of dietary cholesterol Indirect Reduction in serum cholesterol by deconjugating the bile salts .

2.2.10. Enhancing feed intake and digestion Allergies=Infant Health Probiotics in Infant Formulas.

2.3. Improvement the survival of probiotics

2.3.1. micro encapsulation=prebiotic=Other food supplements.


2.4.1. Types of prebiotics -Glucooligosaccharides(GOS) - Fructooligosaccharides(FOS)

2.4.2. Lactosucrose

2.4.3. Applications of Prebiotics Can be consumed as dietary supplements or in functional foods may also be added to the diet, as an alternative to antibiotics. Reduce carriage of enteric pathogens in animal.

3. food preservation

3.1. Food preservation is a process through which physical and /or chemical agents are used to prevent microbial spoilage of food.

3.1.1. Food preservation aims at treating food in a manner to prolong its storage life

3.1.2. In food preservation, efforts are made to destroy organisms in the food,

3.1.3. Increase the period taken by microorganism to adapt to the food environment before they start to spoil the food.

3.2. principles

3.2.1. Inhibition principle inhibition of growth and multiplication of microorganisms. Reduction of water activity e.g. By drying and salting Reduction in pH e.g. by fermentation and addition of acids. Use of preservatives, e.g. sodium benzoate chilling or freezing) Smoking – which has a drying and preservative effect

3.2.2. Killing principle spoilage microorganisms are destroyed (Killed) in the food, the food protected against subsequent contamination by being enclosed in an air tight container.

3.3. Inhibition methods

3.3.1. lowering pH lowering pH so that the growth of spoilage and pathogenic bacteria is prevented. The lowering of pH can be achieved by addition of acids and fermentation Fermentation is the breakdown of carbohydrates under anaerobic conditions into alcohol or lactic acid and carbon dioxide.

3.3.2. by lowering water activity Addition of high content of salt: Sodium chloride and sometimes nitrats and nitrites Addition of high content of sugar Drying: sun/air drying; electrical drying or freeze drying.

3.3.3. salting procedure Dry cure in which the meat or fish is rubbed with salt Pickling The products are immersed in pickle of brine, usually containing about 15% salt. The injection cure concentrated salt injected to muscles Direct addition method

3.3.4. by addition of high content of sugar Monosaccharides Thermophiles Osmophilic

3.3.5. by use of low temperatures Two methods are employed to arrest microbial growth and multiplication. These are chilling (cold storage) and freezing. Chilling is keeping food at temperatures between 0-15oC. The commom chilling temperatures ranges between 4-5 oC. Freezing is keeping food at temperatures between 0 oC and -35oC. Effect of low temperatures Low temperatures are used to retard chemical reactions and actions of food enzymes and to slow down or stop the growth and activity of microorganisms in the food A low enough temperature will prevent growth of any microorganisms Spores are not usually injured at all by freezing. However, most parasites are killed by freezing.

3.4. Killing principle

3.4.1. Methods of killing this shit Heat treatment: pasteurization sterilization Irradiation Use of gases:

3.4.2. Pasteurization Is the process of heat treatment at specific temperatures and times. Pasteurization is aimed at destroying all pathogenic microorganisms without affection the nutritive value of the food. methods of pasteurization Low temperature long time (LTLT) High Temperature short time (HTST) ultra-heat-treating (UHT)

3.4.3. Sterilization Heating at high temperatures, e.g. 100- 140oC Irradiation:Irradiation kills bacteria, spores, and insects as well as inactivates enzymes.

3.5. Applications

3.5.1. use of pasteurization and chilling of milk,

3.5.2. lowering of water activity and low temperature storage

3.5.3. use of preservatives and low temperature

4. food spoilage

4.1. defined as damage or injury to food which becomes unsuitable for human consumption.

4.2. Food must be considered spoiled if it is contaminated with pathogenic microorganisms or various

4.3. Causes of food spoilage

4.3.1. Growth and activity of microorganisms Bacteria, yeasts and molds are microorganisms that cause food spoilage. They produce various enzymes that decompose the various ingredient of food.

4.3.2. Enzyme activity: Action of enzymes found inherently in plant or animal tissues start the decomposition of various food components after death of plant or animal.

4.3.3. Chemical reactions: These are reactions that are not catalysed by enzymes.,e.g. oxidation of fat

4.3.4. Vermin. Vermin includes weevils, ants, rats, cocroaches, important role in food spoilage due to mice, birds, larval stages of some insects. Vermin are play an Possible transmission of pathogenic agents Consumption of food

4.3.5. Physical changes. These include those changes caused by freezing, burning, drying, pressure, etc.

4.4. Microbial spoilage of food

4.4.1. Molds are the major causes of spoilage of foods with reduced water activity e.g dry cereals and cereal product

4.4.2. Bacteria spoil foods with relatively high water activity such as milk and its products.

4.5. Sources of microorganisms in food

4.5.1. Soil and water

4.5.2. Plant and plant products

4.5.3. Food utensils

4.5.4. Intestinal tract of man and animals

4.5.5. Food handlers

4.5.6. Animal hides and skins

4.5.7. Air and dust

4.6. Factors affecting microbial growth

4.6.1. Intrinsic factors Hydrogen ion concentration (pH), Most bacteria grow best at neutral or weakly alkaline pH usually between 6.8 and 7.5. Some bacteria can grow within a narrow pH range of 4.5 and 9.0, e.g. salmonella Other microorganisms especially yeasts Microorganisms that are able to grow in acid environment are called acidophilic microorganisms. These microorganisms are able to grow at pH of around 2.0. Yeasts and molds grow under acid conditions. Other microorganisms such as vibrio cholerae are sensitive to acids and prefer alkaline conditions. Most bacteria are killed in strong acid or strong alkaline environment except Mycobacteria. moisture content The effect of moisture is in terms of water activity: -the amount of free water in a food medium. The amount of free water is important for growth of microorganisms. If there is lack of this free water microorganisms will not grow. Water activity is defined as ) Water activity levels nutrient content of the food Microorganisms require Various foods have specific nutrients that help in microbial growth. Foods such as milk, meat and eggs contain a number of nutrients that are required by microorganisms. These foods are hence susceptible to microbial spoilage antimicrobial substances Antimicrobial substances in food inhibit microbial growth. Various foods have inherent antimicrobial substances that prevent (inhibit) microbial attack. Such inhibitors are like lactenin and anti-coliform factors in milk and lysozyme in eggs. biological structures Some foods have biological structures that prevent microbial entry.

4.6.2. Extrinsic factors Temperature of storage The growth of microorganisms is affected by the envirnmental temperatures. Psychrophilic microorganisms Mesophilic bacteria Thermophilic bacteria. . Presence and concentration of gases in the environment This relates to the presence and concentration of gases in the food environment. Various microorganisms require for growth,either high oxygen tension (aerobic), low oxygen tension (microaerobic) or absence of oxygen (anaerobic). Some microorganisms may grow either in high oxygen tension, or in the absence of oxygen (facultative anaerobes). Foods affected by various groups Relative humidity of food storage environment. Relative humidiy is the amount of moisture in the atmosphere or food environment. Foods with low water activity placed at high humidity environment take up water, increase their water activity and get spoiled easily. For example, dry grains stored in a environment with high humidity will take up water and undergo mold spoilage.


4.7.1. Microbial spoilage

4.7.2. Non- Microbial

4.7.3. Based on rate of spoilage Highly perishable Semi perishable Stable or non-perishable


4.8.1. The organism responsible for taints are acid tolerant bacteria Erwinia carotovora Pseudomonas marginalis Corynebacterium Xanthomonas campestris lactic acid bacteria.

4.8.2. Deterioration can be caused by action of animals birds bruising wounding cutting freezing desiccation growth of microorganisms

4.8.3. Microbial spoilage maybe due to: Plant pathogens acting on stems, leaves, flowers or roots Saprophytic organisms Types of spoilages: Baterial soft rot Anthracnose – Black mold rot Gray mold rot Rhizopus soft rot Alternaria rot


4.9.1. Moisture content above 12 to 13% may cause spoilage of cereals

4.9.2. Water activity above 0.6 cause mold growth.

4.9.3. Microbial types, physical damage and temperature are also some factors.

4.9.4. Aspergillus, Penicillium, Mucor, Rhizopus, Fusarium are some common molds; produce mycotoxins.

4.9.5. The specific type of microbial spoilage of baked bread are moldiness and ropiness.

4.9.6. Molds are the most common and important cause of bread spoilage and other bakery products,

4.9.7. Molds are produces white cottony mycelium and black dots sporangia. Ropiness of bread is common in home baked bread Caused by mucold Bacillus subtilis and other species The spores of these organisms can withstand the temperature Fruity odour is evident, then discolouration (brown mass) and Red bread is caused by the pigmented growth of Serratia marcescens bacteria. Molds such as Neurospora sitophila and Geotrichum aurantiacum can also cause red coloration.


4.10.1. An excellent medium

4.10.2. In milk, the microorganisms that are principally involved in spoilage are psychrotrophic organisms.

4.10.3. Types of Spoilage Gas production caused by Coliform, Clostridium, Yeasts, Bacillus Milk contains lactose which produces acids Proteolysis Proteolysis: Sweet curdling: Roppiness


4.11.1. Raw meat is subject to spoilage by its own enzymes and microbial action.

4.11.2. Factors involving spoilage include off-odour and off-flavour Off-odors such as sweet and fruity, rotten, sulphury and cheesy, characterize aerobically stored meat. Pseudomonas spp., specifically P. fragi produce ethyl esters (fruity odor) at the early stages of spoilage. Sulphur containing compounds contribute to the rotten and sulphury odors. For example hydrogen sulphide formed by Enterobacteriaceae and dimethyl sulphide formed by Pseudomonas spp. Cheesy odors are associated with acetoin diacetyl and 3- methylbutanol formation, produce by Enterobacteriaceae, Brochothrix thermosphacta. – discoloration The bacterial production of hydrogen sulphide converts the muscle pigment to green sulfhemoglobin. Hydrogen sulphide is produced from cysteine and is activated by glucose limitation. Lactobacillus sake forms hydrogen sulphide when the glucose and oxygen availability is limited. gas production Clostridium spp. have been associated with the production of large amounts of gas (H2 and CO2 ).


4.12.1. Spoiled by autolysis, oxidation or bacterial activity.

4.12.2. Under aerobic conditions Surface slime Pseudomonas Moraxella Alcaligens Lactobacillus Streptococcus Leuconostoc Bacillus, Micrococci. Surface colours due to pigmentation Red spot caused by Serratia marcescens Pseudomonas gives a bluish colour Micrococcus or Flavobacterium gives a yellowish colour. Pencillium may cause greenish colour Cladosporium may cause black colour Off odours and Off tastes Putrid and Souring flavour can be caused as a result of bacterial and fungal growth.


4.13.1. The pores in the eggshell and inner membrane do not fully prevent entrance of bacteria and hyphae of molds.

4.13.2. black Proteus vulgaris Aeromonas liquefaciens

4.13.3. Serratia marcescens Red

4.13.4. Enterobacter spp. Custard

4.13.5. Pseudomonas maltophilia Green

4.13.6. Pseudomonas fluorescens Pink

4.13.7. Other Enterobacter and Alcaligenes spp. Colorless


4.14.1. Chemical spoilage Hydrogen swell Discolouration of inside of the can Cloudiness of liquids Loss in nutritive value

4.14.2. Biological spoilage Attacked by Thermophilic and Mesophilic bacteria Flat sour spoilage: Thermophilic Anaerobe spoilage: Sulfide spoilage: Clostridium spp:

5. food borne pathogens and disease

5.1. Food borne diseases (FBD) are acute illnesses associated with the recent consumption of food

5.2. The food involved is usually contaminated with a disease pathogen or toxicant.

5.3. Such food contains enough pathogens or toxicant necessary to make a person sick.

5.4. Classification

5.4.1. Food borne infections Food borne infections are caused by the entrance of pathogenic microorganisms contaminating food into the body, and the reaction of the body tissues to their presence. These can either be fungal, bacterial, viral or parasitic Food borne infections tend to have long incubation periods and are usually characterized by fever Bacterial food borne infections Cholera salmonellosis typhoid fever shigellosis Yersiniosis Escherichia coli infection Campylobacteriosis Vibrio parahaemolyticus Listeriosis Mycotic food borne infections Candida spp Sporothrix spp. Wangiella spp. Viral food borne infections hepatitis A Norwalk virus poliomyelitis virus Salmonellosis The salmonellae constitute a group of organisms with over 2000 different serotypes These organisms are capable of causing disease in animals and man when taken into the body in sufficient numbers Many salmonella species have a wide host range. These are the organisms which commonly cause food poisoning. Salmonellosis cont Control measures Hygienic handling of food. Consumption of properly cooked meat, Heat processing of meat, milk , fish and poultry to destroy salmonella organisms in food Typhoid and Paratyphoid fever (Enteric fevers) Enteric fevers include typhoid and paratyphoid fevers caused by Salmonella typhi and Salmonella paratyphi A, B and C respectively. Transmission Control measures Hygienic control of food and water supplies Detection and treatment of chronic carriers Vaccination using TAB-vaccine. The vaccine contains a mixed culture of S. typhi, and S. paratyphi. The vaccine protects for 5-7 yrs. Escherichia coli food borne infection Escherichia coli are potential food poisoning pathogens which are widely distributed in low numbers in food environments. Produce Shiga Toxin , a poisonous substance Facultative anaerobic bacteria Onset time : 3-8 days Symptoms : Food Sources Vibrio parahemolyticus foodborne Infection Vibrio parahemolyticus is a pathogenic bacterium, whose natural habitat is the sea. Human infections occur solely from sea foods such as oysters, shrimps, crabs, lobsters, and related shellfish. Listeria monocytogenes infection Listeria monocytogenes is a gram positive bacterium that is pathogenic to both animals and human beings Facultative anaerobic bacteria Ability to survive in high salt foods, and can grow at refrigerated temperature. Onset time : 3- 70 days Symptoms : Food Sources: VIRAL FOODBORNE INFECTIONS Viruses are common pathogens transmitted through food. Hepatitis A and Norwalk-like virus (Norovirus) are the most important viral food borne pathogens. These viruses are highly infectious and may lead to widespread outbreaks Characteristics Only a few viral particles are necessary for the disease to develop High numbers of viral particles are further transmitted via feces of infected persons (up to 1011 particles per gram of feces). Specific lining cells are necessary for virus replication. Accordingly they cannot multiply in foods or water. Food borne virus are relatively stable and acid resistant outside host cells Infectious hepatitis A The incubation period is long, being an average of 30 days (range 15-50 days). Found in human intestinal and urinary tract and contaminated water Symptoms : Food sources : Norwalk-like virus (Norovirus) Norovirus infection is relatively mild with an incubation period of 3 days. Symptoms : Food Sources

5.4.2. Food borne intoxications These are diseases caused by consumption of food containing: Biotoxicants Poisonous substances, Metabolic products ( Food borne intoxications have short incubation periods (minutes to hours) and are characterized by absence of fever. Food borne intoxications Bacterial intoxications Fungal intoxications Chemical intoxication Plant toxicants Poisonous animals

6. core concept in hazard analysis and critical points (HACCP)

6.1. (HACCP)

6.1.1. HACCP is a proactive prevention-oriented program that addresses food safety

6.1.2. a systematic, science-based method for identifying and correcting microbiological, chemical and physical hazards that can exist within food manufacturing and handling

6.1.3. universally recognized by industry as an essential element in assuring food safety

6.1.4. it is a proactive rather than reactive

6.1.5. emphasizes food hazard prevention rather than the detection of harmful defects in finished food products aim to prevent contamination of food by pathogens rather than simply detect contamination after it has happen when properly applied, HACCP can significantly reduce the possibility that contamination exists in finished product

6.2. Benefits

6.2.1. protects the trademarks and equity of the food company

6.2.2. ensure that foods put in the public domain are safe and healthy

6.3. Principles of HACCP

6.3.1. Provides a framework in which food processors can systematically focus on critical operations where control is crucial.

6.3.2. Preventing contamination from the beginning and allowing for immediate corrective action if and when problems do occur

6.3.3. Each step is crucial to achieving a successful overall performance of the core

6.4. conducting any hazard analysis:

6.4.1. 1 to conduct investigation that detects hazards, including the source and mode of actual or potential contamination by microbiological, chemical and physical agents to review any data generated from scientific studies, government assessments and/or plant production experiences in terms of actual or potential hazard HACCP plan designers and key members of the company’s team used as much data available as possible to identify all known hazards associated with production, processing and/or preparation of the food during the hazard analysis. collecting the info's : years of experience with processing the food epidemiological data about foodborne diseases associated with the food and factors that contribute to outbreaks tests done to evaluate the process data from examination of food for pH, water activity and/or microorganisms measurement challenge studies observations of daily and periodic operations HACCP team members who are experienced with the operation and knowledgeable about the potential hazards

6.4.2. 2 Definition of critical control points A CCP- QCP=

6.5. decision

6.5.1. Study the flow chart of the process flow time- temperature parameters

6.5.2. If something is made a CCP, you have to monitor it and be able to verify it or the HACCP program will not work

6.6. CCP

6.6.1. A critical limit is a maximum or minimum value to which a biological, chemical or physical limit must be controlled at a CCP.

6.6.2. Select criteria that is specific to the products and the process

6.6.3. The critical limit can be measured

6.6.4. Can verify that hazards are indeed minimized or eliminated

6.6.5. some critical limits are scientifically based- i.e. there is data

6.7. Establish documentation

6.7.1. Keep detailed records of CCP, and other HACCP related activities-proofs of monitoring, corrective action and process verification documents.

6.7.2. Maintenance of records

6.7.3. Auditing

7. TESTING foods for pathogens

7.1. old knowledge

7.1.1. Food Quality control is the multidisciplinary physical, chemical microbiological technological

7.1.2. Method of detection of food adulteration is the core of food quality control program.

7.1.3. Traceability and quality assurance in the food and feed industry through detection technique at every step of the manufacturing chain 'from farm to fork’ are essential for regulatory agencies.

7.2. Detection of pathogens

7.2.1. If pathogens are present in food, only a small population is expected ( usu.<103 cfu/g)

7.2.2. Direct plating of such food gives little or no information: below detection level

7.2.3. Most microbiological analyses of foodborne pathogens- designed to determine their presence or absence in food.

7.2.4. Methods Microscopic - morphological examination - cell counting

7.2.5. .Cultural: qualitative enrichment • isolation quantitative: enumeration

7.3. Resuscitation

7.3.1. Sublethal injury –injury to microbial cells that does not result in cell death

7.3.2. Injured cells – may not multiple until damage is repaired- abnormally long lag phase

7.3.3. Injury is a complex process influenced by time, temp, concentration of injurious agent, strain of the target pathogen, the experimental methodology

7.3.4. -Injury important to food safety for several reasons if injured cells are classified as dead during heat resistance determination, the effect of heating will be overestimated and the resulting heat process will be ineffective injured cells that escape detection at the time of post processing sampling may repair themselves before the food is eaten and cause illness the selective agent may be a common food ingredient, such as salt or organic acids, or even suboptimal temp Staphylococcus aureus cells injured by acid during sausage fermentation can grow on tryptic soy agar but not on tryptic soy agar +7.5% salt. These injured cells can repair themselves in sausage if held at 35 °C and then grow and produce enterotoxin

7.4. Conventional methods

7.4.1. Problem statement Chemistry alone can’t solve all the problems of detection Chemical methods of analysis are time consuming and costly. Need of rapid and reliable methods Methods based on molecular biology and immunology approaches- better alternatives molecular organization in the cell has led to the development of powerful new techniques that bring greater accuracy, rapid, cost effective Molecular methods-more superior than immunological methods.

7.4.2. Common Molecular methods PCR (RT-PCR, Multiplex), restriction fragment length polymorphism (RFLP), Single-strand conformation polymorphism (SSCP) and sequencing. Plasmid profiling, ribotyping, macrorestriction analysis by pulsed-field gel electrophoresis (PFGE). Newer techniques which use fluorescent dyes, DNA microarrays, protein chemistry and mass spectrometry. DNA chip, the GeneChip, Random Amplified Polymorphic DNA Analysis (RAPD) Amplified Fragment Length Polymorphism (AFLP) Loop Mediated Isothermal Amplification (LAMP) Biosensors Gold Nanoparticle-based Biosensor Fiber Optic Biosensor Electrochemical Biosensor Detecting and identifying specific genes (GM foods) Application to Food Authenticity and Legislation Detection of microbial contamination of foods Species Identification Detection of Food Constituents (Ingredients or Contaminants) Detection of antibiotics, pesticides residues etc. Halal certification


7.5.1. RAPD-PCR Pure DNA is not needed Less labor intensive than RFLP. There is no need for prior DNA sequence data.

7.5.2. Ribotyping can identify and classify bacteria based upon differences in ribosomal ribonucleic acid (rRNA).

7.5.3. Plasmid Profiling Plasmid profile analysis involves extraction of plasmid DNA and separation by electrophoresis Plasmid analysis of over 120 strains of Clostridium perfringens, isolated during food-poisoning incidents was carried out by Jones et al A high proportion (71%) of fresh and wellcharacterized food-poisoning strains possessed plasmids of 6.2 kb in size (compared with 19% of non-food-poisoning strains)

7.5.4. Lab-On-A-Chip technology An alternative approach for the visualization of the PCR products by the Capillary electrophoresis (CE) on a card-sized device. Can be used to replace the gel-electrophoretic step in the PCR end-point detection. DNA fragments were detected using laser-induced fluorescence, which enables accurate sizing and quantification of DNA fragments Higher speed, simplicity and safety This approach allowed identification of 5% fish species mixed into a product containing two fish species

7.5.5. Direct Epifluorescence Technique (DEFT) Direct method used for enumeration of microbe based on binding properties of flurochrome acridine orange dye. Food samples are pretreated with detergents and proteolytic enzymes, filtered on to a polycarbonate membrane stained with acridine orange and examined under fluorescent microscope

7.5.6. Electrophoretic methods isoelectric focusing (IEF) urea isoelectric focusing (urea-IEF) sodium dodecyl sulphate – polyacrylamide gel electrophoresis (SDS-PAGE) two dimensional electrophoresis (2DE) capillary electrophoresis (CE)

7.5.7. . biosensor Impedance-based biochip sensor PIEZOELECTRIC BIOSENSOR Detection of viruses in foods