Food Taints and Off-FlavoursM.J. Saxby Springer Science & Business Media, 1996 - 326 pages Contamination of food with extremely low levels of certain compounds can cause an unpleasant taste. This can result in the destruction of vast stocks of product, and very substantial financial losses to food companies. The concentration of the alien compound in the food can be so low that very sophisticated equipment is needed to identify the components and to determine its source. It is vital that every company involved in the production, distribution and sale of foodstuffs are fully aware of the ways in which contamination can accrue, how it can be avoided, and what steps need to be taken in the event that a problem does arise. This book provides the background information needed to recognize how food can become tainted, to draw up guidelines to prevent this contamination, and to plan the steps that should be taken in the event of an outbreak. The new edition has been extensively revised and updated and includes substantial new material on the formation of off flavors due to microbiological and enzymic action, and on sensory evaluation of taints and off flavors A new chapter on off flavors in alcoholic beverages has been added. Written primarily for industrial food technologists, this volume is also an essential reference source for workers in research and government institutions. |
Contents
Sensory evaluation of taints and offflavours | 1 |
12 Thresholds and their measurement | 4 |
13 Sensory descriptions of taints and offflavours | 11 |
14 Principles of sensory evaluation of food | 15 |
142 Hedonic tests | 19 |
143 Requirements for a sensory evaluation operation | 20 |
15 Sensory testing for taint | 21 |
152 Diagnostic taint testing | 25 |
References | 163 |
Oxidative pathways to the formation of offflavours | 168 |
62 Unsaturated lipids as offflavour precursors | 170 |
622 Photosensitised oxidation | 172 |
623 Factors affecting the rate of lipid oxidation | 173 |
624 Formation of hydroperoxides offflavour precursors | 181 |
63 Decomposition of hydroperoxides and types of offflavour compounds | 186 |
631 Aldehydes | 188 |
153 Preventive tainttransfer testing | 26 |
154 Sensory quality control taint testing | 30 |
155 Storage and shelflife testing | 31 |
16 Ethical considerations | 34 |
17 Future developments | 37 |
References | 38 |
A survey of chemicals causing taints and offflavours in food | 41 |
22 Taints derived from known chemicals | 44 |
222 Chlorophenols | 46 |
223 Bromophenols | 48 |
224 Haloanisoles | 49 |
225 Compounds containing sulphur | 53 |
226 Alcohols | 55 |
227 Hydrocarbons | 56 |
228 Esters and ethers | 60 |
229 Amines | 61 |
2210 Chlorinated hydrocarbons | 62 |
2211 Carbonyl compounds | 63 |
2212 Furans and oxygenring compounds | 65 |
2213 Fatty acids | 66 |
Analysis of taints and offflavours | 72 |
32 Instrumental analysis | 73 |
322 Separation | 79 |
323 Identification | 82 |
33 Sensory methods | 83 |
333 Selection of offflavour compounds | 84 |
334 Confirmation of the contribution of identified compounds to the offflavour | 87 |
342 Application of dilution techniques | 88 |
343 Odorous contaminants | 95 |
35 Conclusions | 103 |
Taste and odor problems in drinking water | 107 |
43 Classifying tastes and odors | 108 |
44 The causes of tastes and odors in water supplies | 110 |
45 Causeandeffect relationships in drinking water taste and odor problems | 114 |
46 Specific taste and odorcausing compounds | 115 |
464 Chloramine | 116 |
465 Chlorination byproducts | 117 |
47 Treatment of specific odorous chemicals | 123 |
48 Taste and odor treatment of offodors by chlorination and chloramination | 124 |
49 Taste and odor treatment of offodor by ozonation | 128 |
410 Taste and odor treatment by carbon adsorption | 132 |
411 Summary | 133 |
Undesirable flavors in dairy products | 139 |
53 Transmitted offflavors | 141 |
532 Cowy flavor | 142 |
534 Weed flavor | 143 |
54 Lipolyzed flavor | 144 |
542 Microbial lipases | 145 |
543 Flavor characteristics of lipolytic products | 146 |
55 Microbial flavors | 148 |
553 Fruity flavor | 149 |
554 Green flavor | 150 |
555 Malty flavor | 151 |
56 Heatinduced flavors | 152 |
57 Oxidized flavor | 155 |
572 Reaction products | 158 |
58 Miscellaneous offflavors | 160 |
Acknowledgement | 162 |
632 Ketones | 202 |
633 Furans | 206 |
634 Furanoid fatty acids and dicarbonyl compounds | 208 |
635 Alcohols | 210 |
636 Acids | 212 |
637 Hydrocarbons | 214 |
64 Miscellaneous offflavours and precursors | 215 |
65 Conclusions | 217 |
Acknowledgement | 218 |
Packaging material as a source of taints | 226 |
72 Standard odour and taint assessment methods | 229 |
722 Test methods | 230 |
723 Precautions in selecting transporting and handling samples for sensory testing | 235 |
731 Printing ink and varnish types | 236 |
732 Precautions to prevent odours and tainting from printed packaging | 237 |
733 Methods for determining levels of residual solvents | 239 |
734 Some reported odour and taint investigations | 241 |
74 Paper and board packaging | 242 |
75 Plastics packaging | 246 |
76 Chlorophenols and chloroanisoles | 252 |
77 Scalping of food aromas and flavours by packaging | 254 |
78 Analytical methods for isolating and identifying odorous and tainting substances | 256 |
References | 260 |
A retailers perspective | 264 |
82 Product recall | 265 |
822 What is the problem? | 266 |
823 How widespread? | 267 |
83 Case histories | 268 |
84 Avoidance of taint | 271 |
Acknowledgement | 273 |
Formation of offflavours due to microbiological and enzymic action | 274 |
92 Milk and dairy products | 275 |
923 Other defects | 276 |
932 Legumes | 277 |
933 Brassicas | 279 |
934 Potato | 280 |
94 Wine and beer | 281 |
942 Beer | 283 |
95 Meat and fish | 284 |
96 Concluding remarks | 286 |
Offflavours in alcoholic beverages | 290 |
102 Beer | 292 |
1021 Raw materials | 294 |
7022 Processing | 297 |
1023 Microbiological spoilage | 300 |
1024 Packaging | 303 |
1025 Storage | 305 |
1026 Accidental contamination | 308 |
103 Cider | 309 |
1032 Processing | 310 |
1034 Packaging | 311 |
105 Wine and fortified wine | 312 |
1052 Process | 314 |
1053 Microbial spoilage | 315 |
1055 Storage | 316 |
317 | |
321 | |
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Common terms and phrases
2,4,6-trichloroanisole acetate alcohols aldehydes antioxidants aroma associated autoxidation AWWA bacteria beer bitter carbon cause CH=CH CH₂ Cheddar cheese chemical chloramination chlorine chloroanisoles chlorophenols components compound responsible concentration containing dairy products Dairy Sci decomposition described detected diacetyl drinking water enzyme extraction fatty acids fermentation Figure fishy flavor defect flavour threshold Food Chem food packaging formation Forss fruity gas chromatography geosmin Grosch headspace hydrogen hydrogen sulphide hydroperoxides identified isolated isomers ketones levels linoleate linolenic lipase lipid lipid oxidation Maarse mass spectrometry metallic methods methyl mg/l microbial musty odour threshold off-flavour Oil Chem organoleptic oxidised oxygen ozone packaging materials panellists phenols plastics present problem procedure rancid reaction reported residual result samples sensory analysis solvent sorbic acid specific spectrometry spoilage storage styrene substances Suffet sulphide Table taint testing taste and odor taste threshold Technol temperature threshold values UHT milk unsaturated volatile compounds Whitfield wine yeast µg/kg