193. Microbiological Examination Methods

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193. Microbiological Examination Methods

193. Microbiological Examination Methods

 

 

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Syllabus

Preface XVII
About the authors XIX
List of tables XXI
List of figures XXV
1 Sampling, transport and storage of samples for analysis 1
1.1 Introduction 1
1.1.1 Lot 1
1.1.2 Lot sample and sample unit 1
1.1.3 Lot sampling plans 1
1.1.3.1 The two-class sampling plan 2
1.1.3.2 The three-class sampling plan 2
1.1.4 Analytical unit 2
1.2 Collecting samples for analysis 2
1.2.1 Selection and preparation of containers for the sampling of foods contained
in non-individual packages 3
1.2.2 Procedures for the sampling of foods contained in non-individual packages 3
1.2.3 Sampling of foods involved in foodborne diseases 4
1.2.4 Sampling of water 4
1.3 Transportation and storage of samples until analysis 5
1.3.1 Foods with low water activity 5
1.3.2 Frozen foods 5
1.3.3 Refrigerated foods 5
1.3.4 Commercially sterile foods in sealed packages 6
1.3.5 Water samples 6
1.4 References 7
2 Preparation of sample for analysis 9
2.1 Introduction 9
2.2 Homogenization of samples and withdrawal of the analytical unit 10
2.2.1 Procedure for homogenization and withdrawal of analytical units from liquid products 10
2.2.2 Procedure for homogenization and withdrawal of analytical units from solid
or concentrated liquid products 11
2.2.3 Procedure for withdrawing the analytical unit using the surface swabbing technique 11
2.2.3.1 Swab sampling 11
2.2.3.2 Sponge sampling 12
2.2.4 Procedure for withdrawing the analytical unit using the surface washing technique 12
2.2.4.1 Procedure for washing poultry carcasses 12
2.2.4.2 Procedure for washing other foods 14
2.2.4.3 Procedure for washing packages 14
2.2.5 Keeping of counter-samples 14
2.3 Preparation of the first dilution of the analytical unit 15
2.3.1 Diluents for presence/absence tests 15
2.3.2 Diluents for tests requiring differentiated handling of the sample 15

2.3.3 Diluents for general quantification tests 15
2.3.4 How to prepare an initial 1:10 (10–1) dilution 15
2.3.5 How to prepare an initial dilution different from 1:10 15
2.3.6 Procedure for the preparation of the first dilution of liquid samples 15
2.3.7 Procedure for the preparation of the first dilution of solid or concentrated
liquid samples 16
2.3.8 Procedure for the preparation of the first dilution of samples obtained
by surface swabbing or surface washing 16
2.4 Serial decimal dilution of the sample 16
2.5 References 17
Annex 2.1 – Procedures for the homogenization of the content and withdrawal of the analytical unit
of different types of foods 18

Annex 2.2 – Special cases in which there are variations in the analytical unit and/or dilution
and/or diluents recommended for the preparation of the first dilution of samples
of different types of foods 19
3 Basic plate count techniques for the enumeration of microorganisms 23
3.1 Introduction 23
3.2 Pour plate technique 23
3.2.1 Material required for the analyses 24
3.2.2 Procedure 24
3.3 Spread plate technique 25
3.3.1 Material required for the analyses 26
3.3.2 Procedure 26
3.4 Drop plate technique 27
3.4.1 Material required for the analyses 27
3.4.2 Procedure 27
3.5 Membrane filtration 27
3.5.1 Material required for the analyses 28
3.5.2 Procedure 28
3.6 Counting colonies and calculating results 29
3.6.1 Pour plate calculations 29
3.6.1.1 Calculating the pour plate results in the standard situation 30
3.6.1.2 Calculating the pour plates results for samples prepared by the surface
swabbing technique (swabs or sponges) 33
3.6.1.3 Calculating the pour plate results for samples prepared by the surface
washing technique 34
3.6.2 Spread plate calculations 34
3.6.3 Drop plate calculations 34
3.6.4 Membrane filtration calculations 35
3.7 Counting colonies and calculating results according to ISO 7218:2007 35
3.8 References 37
4 Basic techniques for microbial enumeration by the most probable number method (MPN) 39
4.1 Introduction 39
4.2 Multiple dilution test 40
4.2.1 Material required for the analyses 41
4.2.2 Procedure 41
4.3 Single dilution test 42
4.3.1 Material required for the analyses 42

4.3.2 Procedure 42
4.4 Calculation of the results 42
4.4.1 Calculating the results of the multiple dilution test 43
4.4.1.1 Calculation using the MPN tables (for decimal dilutions) 43
4.4.1.2 Calculating using the Thomas formula (for non-decimal dilutions) 44
4.4.1.3 Calculating the results for samples prepared by the surface swabbing
or surface washing techniques 44
4.4.2 Calculating the results of the single dilution test 44
4.4.2.1 Rules for calculations performed using the MPN-3 Table 45
4.4.2.2 Calculation for samples prepared by the surface swabbing or surface washing
techniques 45
4.5 References 45
Annex 4.1 – MPN tables 46
5 Basic techniques for the detection of the presence/absence of microorganisms 49
5.1 Introduction 49
5.1.1 Enrichment 49
5.1.1.1 Pre-enrichment 49
5.1.1.2 Selective enrichment 50
5.1.2 Isolation in solid media (selective differential plating) 50
5.1.3 Confirmation 50
5.1.3.1 Catalase test 51
5.1.3.2 Citrate test 51
5.1.3.3 Amino acid decarboxylation tests 51
5.1.3.4 Phenylalanine deaminase test 51
5.1.3.5 Carbohydrate fermentation tests 51
5.1.3.6 Indole test 52
5.1.3.7 Malonate test 52
5.1.3.8 Oxidation/Fermentation test (O/F) 52
5.1.3.9 Oxidase test 52
5.1.3.10 Nitrate reduction test 53
5.1.3.11 Urease test 53
5.1.3.12 Methyl Red test (MR) 53
5.1.3.13 Voges-Proskauer test (VP) 53
5.2 Material required for the analyses 54
5.3 Procedure 54
5.3.1 Pre-enrichment 54
5.3.2 Selective enrichment 54
5.3.3 Selective differential plating 54
5.3.3.1 Streak plating technique for obtaining pure cultures 54
5.3.4 Selection of colonies and subculturing of cultures for confirmation 55
5.3.4.1 Technique for the subculturing of pure cultures starting
from colonies isolated from plates 55
5.3.5 Confirmation tests 55
5.3.5.1 Gram-staining (Hucker’s method) 55
5.3.5.2 Spore-staining (Schaeffer-Fulton’s method) 56
5.3.5.3 Spore-staining (Ashby’s method) 56
5.3.5.4 Wet mounts for direct (fresh) microscopic observation 56
5.4 References 56

6 Aerobic plate count 57
6.1 Introduction 57
6.1.1 The importance and significance of the total aerobic mesophilic count 57
6.1.2 Definition of psychrotrophics 58
6.1.3 Methods of analysis 58
6.2 Plate count method APHA 2001 for aerobic mesophilic bacteria in foods and water 59
6.2.1 Material required for analysis 60
6.2.2 Procedure 60
6.2.2.1 Pour plate technique 60
6.2.2.2 Spread plate technique 61
6.2.2.3 Membrane filtration technique 62

6.3 PetrifilmTM AOAC official methods 990.12 – 989.10 – 986.33 for aerobic mesophilic
bacteria in foods 63
6.3.1 Material required for analysis 63
6.3.2 Procedure 63
6.4 Plate count method APHA 2001 for aerobic psychrotrophic bacteria in foods 64
6.4.1 Material required for analysis 64
6.4.2 Procedure 64
6.5 References 65
7 Yeasts and molds 67
7.1 Introduction 67
7.1.1 Yeasts and molds in foods 67
7.1.2 Methods of analysis for total yeast and mold counts 68
7.1.3 Psychrotrophic fungi 68
7.1.4 Heat-resistant molds 68
7.1.5 Preservative-resistant yeasts (PRY) 69
7.1.5.1 Zigosaccharomyces bailii (Lindner) Guilliermond 1912 69
7.1.5.2 Zygosaccharomyces bisporus (Naganishi) Lodder and Kreger 1952 70
7.1.5.3 Schizosaccharomyces pombe Lindner 1893 70
7.1.5.4 Candida krusei (Castellani) Berkhout 1923 70
7.1.5.5 Pichia membranaefaciens Hansen 1904 70
7.1.6 Osmophilic yeasts 71
7.1.6.1 Zygosaccharomyces rouxii (Boutroux) Yarrow 71
7.2 Plate count method APHA 2001 for yeasts and molds in foods 71
7.2.1 Material required for analysis 72
7.2.2 Procedure 72
7.3 Plate count method APHA 2001 for psychrotrophic fungi in foods 74
7.3.1 Material required for analysis 74
7.3.2 Procedure 74
7.4 Plate count method APHA 2001 for heat-resistant molds in foods 76
7.4.1 Material required for analysis 76
7.4.2 Procedure 76
7.5 Presence/absence method Pitt and Hocking 2009 and Plate count method Pitt
and Hocking 2009 for preservative-resistant yeasts in foods 78
7.5.1 Material required for analysis 78
7.5.2 Procedure 78
7.6 Membrane filtration method APHA 2001 and Plate count method
APHA 2001 for osmophilic yeasts in foods 80
7.6.1 Material required for analysis 80
7.6.2 Procedure 80
7.7 References 81

8 Enterobacteriaceae 83
8.1 Introduction 83
8.1.1 Taxonomy 83
8.1.2 Methods of analysis 84
8.2 Plate count method APHA 2001 for Enterobacteriaceae in foods 84
8.2.1 Material required for analysis 84
8.2.2 Procedure 84
8.3 Most probable number (MPN) method APHA 2001 for Enterobacteriaceae in foods 85
8.3.1 Material required for analysis 85
8.3.2 Procedure 85
8.4 PetrifilmTM AOAC official method 2003.1 for Enterobacteriaceae in selected foods 87
8.4.1 Material required for analysis 87
8.4.2 Procedure 87
8.5 References 88
9 Total and thermotolerant coliforms and Escherichia coli 89
9.1 Introduction 89
9.1.1 Definition of total coliforms 89
9.1.2 Definition of thermotolerant coliforms 89
9.1.3 Escherichia coli 89
9.1.4 Use as indicators 90
9.1.5 Methods of analysis 90
9.2 Most probable number (MPN) method APHA 2001 for total coliforms, thermotolerant
coliforms and E. coli in foods 92
9.2.1 Material required for analysis 92
9.2.2 Procedure 93
9.3 Most probable number (MPN) methods ISO 4831:2006 and ISO 7251:2005 for total
coliforms and presumptive E. coli in foods 97
9.3.1 Material required for analysis 97
9.3.2 Procedure 97
9.4 Most probable number (MPN) method APHA/AWWA/WEF 2005 for total
and thermotolerant coliforms and E. coli in water 99
9.4.1 Material required for analysis 99
9.4.2 Procedure 101
9.5 Plate count method APHA 2001 for total coliforms in foods 102
9.5.1 Material required for analysis 102
9.5.2 Procedure 102
9.6 References 103
10 Staphylococcus aureus 105
10.1 Introduction 105
10.1.1 Taxonomy 105
10.1.1.1 The genus Staphylococcus 105
10.1.1.2 The coagulase positive staphylococci 105
10.1.1.3 Staphylococcus aureus 106
10.1.2 Pathogenicity 107
10.1.2.1 Staphylococcus aureus enterotoxins 107
10.1.2.2 Staphylococcal food poisoning 108
10.1.3 Methods of analysis 108
10.2 Plate count method APHA 2001 for coagulase positive staphylococci and S. aureus in foods 109
10.2.1 Material required for analysis 110
10.2.2 Procedure 110

10.3 Most probable number (MPN) method APHA 2001 for coagulase positive staphylococci
and S. aureus in foods 113
10.3.1 Material required for analysis 113
10.3.2 Procedure 113
10.4 Presence/absence method APHA 2001 for coagulase positive staphylococci
and S. aureus in foods 115
10.4.1 Material required for analysis 115
10.4.2 Procedure 115
10.5. References 115
11 Bacillus cereus 119
11.1 Introduction 119
11.1.1 B. cereus Group 119
11.1.2 Main characteristics of B. cereus 120
11.1.3 Methods of analysis 121
11.2 Plate count method APHA 2001 for Bacillus cereus in foods 121
11.2.1 Material required for analysis 122
11.2.2 Procedure 122
11.3 Most probable number (MPN) method APHA 2001 for Bacillus cereus in foods 126
11.3.1 Material required for analysis 126
11.3.2 Procedure 126
11.4 References 126
12 Clostridium perfringens 129
12.1 Introduction 129
12.1.1 Main characteristics of C. perfringens 129
12.1.2 Epidemiology 130
12.1.2.1 C. perfringens type A food poisoning 130
12.1.2.2 C. perfringens type C necrotic enteritis 130
12.1.3 Methods of analysis 130
12.2 Plate count method APHA 2001 for Clostridium perfringens in foods 131
12.2.1 Material required for analysis 131
12.2.2 Procedure 132
12.3 Presence/absence method APHA 2001 for Clostridium perfringens in foods 134
12.3.1 Material required for analysis 134
12.3.2 Procedure 134
12.4 References 136
13 Enterococci 137
13.1 Introduction 137
13.1.1 Enterococci 139
13.1.1.1 Species of intestinal origin 139
13.1.1.2 Species found in plants, soil and water 140
13.1.1.3 Species found in foods 140
13.1.1.4 Biochemical characteristics of the genus Enterococcus 141
13.1.2 Fecal streptococci 141
13.1.2.1 Biochemical characteristics of the genus Streptococcus 142
13.1.3 Diferentiation of enterococci from fecal streptococci 142
13.1.4 Methods of analysis 142

13.2 Plate count method APHA 2001 for enterococci and fecal streptococci in foods 143
13.2.1 Material required for analysis 143
13.2.2 Procedure 144
13.3 Most probable number (MPN) method APHA 2001 for enterococci and fecal streptococci in foods 145
13.3.1 Material required for analysis 145
13.3.2 Procedure 145
13.4 Membrane filtration method APHA/AWWA/WEF 2005 for enterococci
and fecal streptococci in water 145
13.4.1 Material required for analysis 145
13.4.2 Procedure 146
13.5 Membrane filtration method ISO 7899-2:2000 for intestinal enterococci in water 148
13.5.1 Material required for analysis 148
13.5.2 Procedure 148
13.6 References 149
14 Lactic acid bacteria 151
14.1 Introduction 151
14.1.1 Carnobacterium Collins et al. 1987 151
14.1.2 Enterococcus (ex Thiercelin & Jouhaud 1903) Schleifer & Kilpper-Bälz 1984 153
14.1.3 Fructobacillus Endo and Okada 2008 153
14.1.4 Lactobacillus Beijerinck 1901 emend. Haakensen et al. 2009 154
14.1.5 Lactococcus Schleifer et al. 1986 154
14.1.6 Leuconostoc van Tieghem 1878 155
14.1.7 Oenococcus Dicks et al. 1995 emend. Endo and Okada 2006 155
14.1.8 Pediococcus Balcke 1884 156
14.1.9 Streptococcus Rosenbach 1884 156
14.1.10 Tetragenococcus Collins et al. 1993 156
14.1.11 Weissella Collins et al. 1994 157
14.1.12 Methods of analysis 157
14.2 Plate count method APHA 2001 for lactic acid bacteria in foods 160
14.2.1 Material required for analysis 160
14.2.2 Procedure 160
14.3 Most probable number (MPN) methods APHA 2001 for lactic acid bacteria in foods 162
14.3.1 Material required for analysis 162
14.3.2 Procedure using the MRS broth 162
14.3.3 Procedure using the Rogosa SL Broth 162
14.4 References 165
15 Campylobacter 167
15.1 Introduction 167
15.1.1 Taxonomy 167
15.1.2 Epidemiology 169
15.2 Presence/absence method ISO 10272-1:2006 for thermotolerant Campylobacter in foods 169
15.2.1 Material required for analysis 170
15.2.2 Procedure 170
15.3 References 173
16 Cronobacter 175
16.1 Introduction 175
16.1.1 Taxonomy 175

16.1.1.1 Cronobacter Iversen et al. 2008, gen. nov. 175
16.1.2 Epidemiology 175
16.1.3 Codex Alimentarius microbiological criteria for Cronobacter spp. in powdered infant formulae 176
16.2 Presence/absence method ISO 22964:2006 for Cronobacter [Enterobacter sakazakii] in milk
powder and powdered infant formula 177
16.2.1 Material required for analysis 177
16.2.2 Procedure 178
16.3 References 180
17 Pseudomonas 181
17.1 Introduction 181
17.1.1 Taxonomy 181
17.1.1.1 Pseudomonas Migula 1894 181
17.1.1.2 Shewanella MacDonell & Colwell 1986 184
17.1.1.3 Janthinobacterium De Ley et al. 1978 emend. Lincoln et al. 1999 185
17.1.1.4 Stenotrophomonas Palleroni & Bradbury 1993 186

17.2 Most probable number (MPN) method APHA/AWWA/WEF 2005
for Pseudomonas aeruginosa in water 186
17.2.1 Material required for analysis 186
17.2.2 Procedure 187
17.3 Membrane filtration method ISO 16266:2006 for Pseudomonas aeruginosa in water 188
17.3.1 Material required for analysis 188
17.3.2 Procedure 188
17.4 Plate count method ISO 13720:2010 for presumptive Pseudomonas spp. in meat and meat products 190
17.4.1 Material required for analysis 191
17.4.2 Procedure 191
17.5 Plate count method ISO 11059:2009 IDF/RM 225:2009 for Pseudomonas spp.
in milk and milk products 193
17.5.1 Material required for analysis 194
17.5.2 Procedure 194
17.6 References 196
18 Listeria monocytogenes 197
18.1 Introduction 197
18.1.1 Taxonomy 197
18.1.2 Epidemiology 198
18.1.3 Methods of analysis 199
18.2 Presence/absence method BAM/FDA 2011 for Listeria monocytogenes in foods 200
18.2.1 Material required for analysis 200
18.2.2 Procedure 200
18.3 Presence/absence method MLG/FSIS/USDA 2009 for Listeria monocytogenes in foods 204
18.3.1 Material required for analysis 204
18.3.2 Procedure 206
18.4 Plate count method ISO 11290-2:1998 Amendment 1:2004 for Listeria monocytogenes in foods 207
18.4.1 Material required for analysis 207
18.4.2 Procedure 209
18.5 Presence/absence method ISO 11290-1:1996 Amendment 1:2004 for Listeria monocytogenes in foods 212
18.5.1 Material required for analysis 212
18.5.2 Procedure 212
18.6 References 214

19 Salmonella 217
19.1 Introduction 217
19.1.1 Taxonomic classification of Salmonella 217
19.1.2 Serological classification of Salmonella 219
19.1.3 Biochemical characteristics of Salmonella 221
19.1.4 Epidemiology 221
19.1.5 Traditional methods used for the examination of Salmonella 223
19.1.6 Alternative methods for the analysis of Salmonella 225
19.1.7 Composite samples for analysis 225
19.2 Presence/absence method ISO 6579:2002 Amendment 1:2007 for Salmonella in foods 227
19.2.1 Material required for analysis 227
19.2.2 Procedure 227
19.3 Presence/absence method BAM/FDA 2011 for Salmonella in foods 232
19.3.1 Material required for analysis 232
19.3.2 Procedure 232
19.4 Presence/absence method MLG/FSIS/USDA 2011 for Salmonella in foods 242
19.4.1 Material required for analysis 242
19.4.2 Procedure 242
19.5 References 247
20 Vibrio cholerae and Vibrio parahaemolyticus 249
20.1 Introduction 249
20.1.1 Taxonomy 249
20.1.2 Epidemiology 253
20.1.2.1 V. cholerae 254
20.1.2.2 V. parahaemolyticus 254
20.1.2.3 V. vulnificus 254
20.1.3 Methods of analysis 255
20.2 Presence/absence method APHA 2001 and BAM/FDA 2004 for Vibrio cholerae in foods 255
20.2.1 Material required for analysis 256
20.2.2 Procedure 256
20.3 Most probable number (MPN) method APHA 2001 and BAM/FDA 2004
for Vibrio parahaemolyticus in foods 258
20.3.1 Material required for analysis 258
20.3.2 Procedure 259
20.4 Presence/absence method ISO 21872-1:2007 for presumptive enteropathogenic
Vibrio cholerae and Vibrio parahaemolyticus in foods 261
20.4.1 Material required for analysis 261
20.4.2 Procedure 261
20.5 References 265
21 Yersinia enterocolitica 267
21.1 Introduction 267
21.1.1 Taxonomy 267
21.1.2 Epidemiology 270
21.2 Presence/absence method ISO 10273:2003 for presumptive pathogenic
Yersinia enterocolitica in foods 270
21.2.1 Material required for analysis 271
21.2.2 Procedure 271
21.3 References 275

22 Bacterial spore count 277
22.1 Introduction 277
22.1.1 The bacterial spore 277
22.1.1.1 Sequence of spore formation 277
22.1.1.2 Spore ultrastructure 277
22.1.1.3 Mechanisms of spore resistance 278
22.1.2 Taxonomy of sporeforming bacteria important in foods 278
22.1.2.1 Aeribacillus Miñana-Galbis et al. 2010 278
22.1.2.2 Alicyclobacillus Wisotzkey et al. 1992 emend. Goto et al. 2003 emend.
Karavaiko et al. 2005 279
22.1.2.3 Aneurinibacillus Shida et al. 1996 emend. Heyndrickx et al. 1997 281
22.1.2.4 Anoxybacillus Pikuta et al. 2000 emend. Pikuta et al. 2003 281
22.1.2.5 Bacillus Cohn 1872 282
22.1.2.6 Brevibacillus Shida et al. 1996 283
22.1.2.7 Clostridium Prazmowski 1880 284
22.1.2.8 Cohnella Kämpfer et al. 2006 287
22.1.2.9 Desulfotomaculum Campbell and Postgate 1965 287
22.1.2.10 Geobacillus Nazina et al. 2001 287
22.1.2.11 Jeotgalibacillus Yoon et al. 2001 emend. Chen et al. 2010 288
22.1.2.12 Lentibacillus Yoon et al. 2002 emend. Jeon et al. 2005 288
22.1.2.13 Lysinibacillus Ahmed et al. 2007 289
22.1.2.14 Moorella Collins et al. 1994 289
22.1.2.15 Oceanobacillus Lu et al. 2002 emend. Lee et al. 2006 289
22.1.2.16 Paenibacillus Ash et al. 1994 emend. Shida et al. 1997 290
22.1.2.17 Sporolactobacillus Kitahara and Suzuki 1963 290
22.1.2.18 Thermoanaerobacter Wiegel and Ljungdahl 1982 emend. Lee et al. 2007 290
22.1.2.19 Thermoanaerobacterium Lee et al. 1993 291
22.1.2.20 Virgibacillus Heyndrickx et al. 1998 emend. Wainø et al. 1999 emend.
Heyrman et al. 2003 291

22.2 Methods APHA 2001 for spores of total and “flat sour” thermophilic aerobic
sporeformers in foods 292
22.2.1 Material required for analysis 292
22.2.2 Procedure for the analysis of sugar 292
22.2.3 Procedure for the analysis of starch 293
22.2.4 Procedure for the analysis of whole tomatoes, tomato pulp, tomato puree
and concentrated milk 293
22.2.5 Procedure for the analysis of nonfat dry milk 294
22.2.6 Procedure for the analysis of milk cream 294
22.2.7 Procedure for the analysis of other foods and ingredients (general) 294
22.3 Methods APHA 2001 for spores of thermophilic anaerobic sporeformers in foods 296
22.3.1 Material required for analysis 296
22.3.2 Procedure for the analysis of sugar and powdered milk 296
22.3.3 Procedure for the analysis of starches and flours 297
22.3.4 Procedure for the analysis of cereals and alimentary pastes 297
22.3.5 Procedure for the analysis of fresh mushrooms 297
22.3.6 Procedure for the analysis of “in-process” products 297
22.4 Methods APHA 2001 for spores of sulfide spoilage anaerobic sporeformers in foods 298
22.4.1 Material required for analysis 298
22.4.2 Procedure for the analysis of sugar 298
22.4.3 Procedure for the analysis of starch and flour 298

22.4.4 Procedure for the analysis of skim milk powder 299
22.4.5 Procedure for the analysis of soy protein isolates 299
22.5 Methods APHA 2001 for spores of mesophilic aerobic sporeformers in foods 299
22.5.1 Material required for analysis 299
22.5.2 Procedure for foods in general 300
22.5.3 Procedure for the analysis of milk and dairy products 300
22.5.4 Procedure for the analysis of water 302
22.6 Methods APHA 2001 for spores of mesophilic anaerobic sporeformers in foods 302
22.6.1 Material required for analysis 302
22.6.2 Procedure for the analysis of sugar 302
22.6.3 Procedure for the analysis of starch, flours and other cereal products 303
22.6.4 Procedure for the analysis of dehydrated vegetables 303
22.6.5 Procedure for the analysis of seasonings and spices 303
22.6.6 Procedure for the analysis of egg powder, milk powder and other
powdered dairy products 303
22.6.7 Procedure for the analysis of fluid milk and cheeses 304
22.6.8 Other procedures for mesophilic anaerobic sporeformers 304
22.7 Methods IFU 12:2007 for Alicyclobacillus in foods 304
22.7.1 Material required for analysis 305
22.7.2 Procedure for the analysis of raw material 305
22.7.3 Procedure for analysis of the finished product 306
22.7.4 Interpretation and calculation of the results 307
22.8 References 307
23 Commercial sterility 311
23.1 Introduction 311
23.1.1 Parameters for evaluating the heat resistance of microorganisms 312
23.1.1.1 Survival curve and decimal reduction time (D value) 312
23.1.1.2 Number of decimal reductions 312
23.1.1.3 Thermal destruction curve and temperature coefficient (z value) 312
23.1.2 D and z values of microorganisms of importance in foods 313
23.1.3 Dimensioning heat treatments and thermal processing 316
23.1.4 Microbial spoilage of canned foods 317
23.2 Method APHA 2001 for commercial sterility or cause of spoilage of low acid canned foods 318
23.2.1 Material required for analysis 319
23.2.2 Procedure 319
23.2.3 Interpretation of the results 323
23.3 Method APHA 2001 for commercial sterility or cause of spoilage of acid canned foods 326
23.3.1 Material required for analysis 326
23.3.2 Procedure 327
23.3.3 Interpretation of the results 330
23.4 References 332
24 Guidelines on preparation of culture media 335
24.1 Introduction 335
24.1.1 Ingredients used in the formulation of culture media 335
24.1.1.1 Water for preparing media and reagents 335
24.1.1.2 Nutrient sources for culture media 335
24.1.1.3 Selective agents 338
24.1.1.4 Differential agents 338

24.1.1.5 Reducing agents 338
24.1.1.6 Buffering agents 339
24.1.1.7 Chromogenic and fluorogenic substrates 339
24.1.1.8 Agar 340
24.1.2 Types of culture media 340
24.2 Procedure for the preparation of culture media 341
24.2.1 Storing supplies and ingredients for preparation of culture media 341
24.2.2 Weighing and rehydration 341
24.2.3 Dissolution and dispersion 341
24.2.4 Verification and adjustment of the pH before sterilization 342
24.2.5 Distribution 342
24.2.6 Sterilization by moist heat 342
24.2.7 Sterilization by filtration 343
24.2.8 Verification after sterilization 344
24.2.9 Preparation of supplements for culture media 344
24.2.10 Storage of sterilized media until the moment of use 344
24.2.11 Preparation of the media at the moment of use 344
24.3 References 345
Annex 1 – Preparation of media and reagents 347
Annex 2 – Sampling plans and microbiological limits recommended by ICMSF for foods 437
Subject index 445

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Medifit issues Lifetime validity certificates for all Online Courses provided. No need to renew the certificates every 2 or 3 years. All Courses Certificates of Medifit are having Lifetime Validity. No need to renew these certificates every 2 or 3 years.

 

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Vast number of students applying for Job in international market of Fitness through Medifits Online Courses Certificates. And most importantly, the Medical standards maintained, helps to acquire jobs internationally. This gives very strong International acceptance to Certificates of Medifit Courses.

 

ABOUT MEDIFIT ACADEMY CERTIFICATION COURSE:

Medifit Education Online Academy is an innovative, digital and engaging education platform that delivers fast track accredited courses and skills development courses instantly online, with no time limits, enabling individuals to study anywhere and anytime. We are proud to offer international standard courses that have helped our students build their careers across the globe.

HOW DO MEDIFIT ONLINE CERTIFICATE COURSES HELP?

Short term Professional Courses International Standards courses Opens Global opportunities Career defining Courses Skill Development Programmes Knowledge in short span Learn at your own pace Certification of Completion Immediate Earning Opportunities Positive Social Impact Optimistic Psychological Benefits Improved Standard of Living Study from anywhere & anytime Very Economical Fees

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