474 Modern Food Microbiology
Table 20–1 Some Organisms that are Negatively Correlated
with Product Quality
Organisms
Products
Acetobacter spp.
Fresh cider
Bacillus spp.
Bread dough
Byssochlamys spp.
Canned fruits
Clostridium spp.
Hard cheeses
Flat-sour spores
Canned vegetables
Geotrichum spp.
Fruit cannery sanitation
Lactic acid bacteria
Beers, wines
Lactococcus lactis
Raw milk (refrigerated)
Leuconostoc mesenteroides
Sugar (during refinery)
Pectinatus cerevisiiphilus
Beers
“Pseudomonas putrefaciens”
Butter
Yeasts
Fruit juice concentrates
Zygosaccharomyces bailii
Mayonnaise, salad dressing
Metabolic products may be used to assess and predict microbial quality in some products; and
some examples are listed in Table 20–2. The diamines (cadaverine and putrescine), histamine, and
polyamines have been found to be of value for several products (discussed further in Chapter 4).
Diacetyl was found to be the best negative predictor of quality in frozen orange juice concentrates,
where it imparts a buttermilk aroma at levels of 0.8 ppm or above.
62 A 30-minute method for its
detection was developed by Murdock.
61 Ethanol has been suggested as a quality index for canned
salmon, where 25–74 ppm were associated with “offness,” and levels higher than 75 ppm indicated
spoilage.
35 Ethanol was found to be the most predictive of several alcohols in fish extracts stored
at 5
◦ C, where 227 of 241 fish-spoilage isolates produced this alcohol.
3 Lactic acid was the most
frequently found organic acid in spoiled canned vegetables, and a rapid (2-hour) silica-gel plate method
was developed for its detection.
1 The production of trimethylamine (TMA) from trimethylamine-N -
oxide by fish spoilers has been used by a large number of investigators as a quality or spoilage
index. Various procedures have been employed to measure total volatile substances as indicators of
Table 20–2 Some Microbial Metabolic Products That Negatively Correlate with
Food Quality
Metabolites
Applicable Food Product
Cadaverine and putrescine
Vacuum-packaged beef
Diacetyl
Frozen juice concentrate
Ethanol
Apple juice, fishery products
Histamine
Canned tuna
Lactic acid
Canned vegetables
Trimethylamine (TMA)
Fish
Total volatile bases (TVB), total volatile
nitrogen (TVN)
Seafoods
Volatile fatty acids
Butter, cream
Table 20–1 Some Organisms that are Negatively Correlated
with Product Quality
Organisms
Products
Acetobacter spp.
Fresh cider
Bacillus spp.
Bread dough
Byssochlamys spp.
Canned fruits
Clostridium spp.
Hard cheeses
Flat-sour spores
Canned vegetables
Geotrichum spp.
Fruit cannery sanitation
Lactic acid bacteria
Beers, wines
Lactococcus lactis
Raw milk (refrigerated)
Leuconostoc mesenteroides
Sugar (during refinery)
Pectinatus cerevisiiphilus
Beers
“Pseudomonas putrefaciens”
Butter
Yeasts
Fruit juice concentrates
Zygosaccharomyces bailii
Mayonnaise, salad dressing
Metabolic products may be used to assess and predict microbial quality in some products; and
some examples are listed in Table 20–2. The diamines (cadaverine and putrescine), histamine, and
polyamines have been found to be of value for several products (discussed further in Chapter 4).
Diacetyl was found to be the best negative predictor of quality in frozen orange juice concentrates,
where it imparts a buttermilk aroma at levels of 0.8 ppm or above.
62 A 30-minute method for its
detection was developed by Murdock.
61 Ethanol has been suggested as a quality index for canned
salmon, where 25–74 ppm were associated with “offness,” and levels higher than 75 ppm indicated
spoilage.
35 Ethanol was found to be the most predictive of several alcohols in fish extracts stored
at 5
◦ C, where 227 of 241 fish-spoilage isolates produced this alcohol.
3 Lactic acid was the most
frequently found organic acid in spoiled canned vegetables, and a rapid (2-hour) silica-gel plate method
was developed for its detection.
1 The production of trimethylamine (TMA) from trimethylamine-N -
oxide by fish spoilers has been used by a large number of investigators as a quality or spoilage
index. Various procedures have been employed to measure total volatile substances as indicators of
Table 20–2 Some Microbial Metabolic Products That Negatively Correlate with
Food Quality
Metabolites
Applicable Food Product
Cadaverine and putrescine
Vacuum-packaged beef
Diacetyl
Frozen juice concentrate
Ethanol
Apple juice, fishery products
Histamine
Canned tuna
Lactic acid
Canned vegetables
Trimethylamine (TMA)
Fish
Total volatile bases (TVB), total volatile
nitrogen (TVN)
Seafoods
Volatile fatty acids
Butter, cream