Microbial food spoilage Flashcards
- the undesirable deterioration of food quality that may result in changes in odor, taste, and appearance of food
- to destroy the value or quality of a food
- refers to the process of decay itself
Food spoilage
Criteria for acceptable foods:
- It should be at a stage of development or maturity.
- It must be free from pollution at any stage in the production.
- It must be free from undesirable biological, chemical, and physical changes.
- It must be free from pathogenic microorganisms.
Types of agents causing food spoilage (chemical, biological, or physical)
- Growth and activity of microorganisms: bacteria, yeasts, and molds.
- Insects, rodents, or animals.
- Action of the enzymes naturally present in the plant or animal food, such as degradation of vegetables by pectinases and fish by proteinases.
- Reactions in the food, such as browning and oxidation.
- Changes, such as changes from freezing, burning, drying, and pressure.
- Presence of foreign material in the food, such as heavy metals, toxins, and nonfood materials.
- Presence of parasites or their eggs.
Undesirable changes that can occur in foods
Texture
- loss of solubility
- loss of water-holding capacity
- toughening
- softening
Flavor
- development of rancidity, cooked or caramel flavors
- other off-flavors
Color
- darkening
- bleaching
- development of other off-colors
Appearance
- increase in particle size
- decrease in particle size
- non-uniformity of particle size
Nutritive value
- loss or degradation of vitamins, minerals, proteins, lipids
Safety
- generation of toxic substances
3 most important types of spoilage:
- Microbial
- Chemical
- Physical
Type of spoilage:
- due to physical damage to food during harvesting, processing, or distribution
- increases the chance of chemical or microbial spoilage and contamination because the protective outer layer of the food is bruised or broken and microorganisms can enter the foodstuff more easily
-example: staling of baked products, physical separation of components, moisture loss or gain by foods
Physical spoilage
Type of spoilage:
- when foods are removed from its natural source, chemical changes begin with the deterioration of food structure
- chemical reactions alter edible quality, including deterioration in color, appearance, texture, aroma, flavor, nutrition, safety, and functional properties
Chemical spoilage
2 types of chemical spoilage
- Nonezymatic browning - occurs during the roasting, baking, grilling, and frying of many foods
a. Maillard reactions - the reaction of carbonyl groups (such as reducing sugar, aldehydes, ketones, and lipid oxidation products) and amino compounds (such as lysine, glycine, peptide, amine, and ammonia proteins)
Protein + Sugar + Heat = Color, flavor, and aroma of baked bread.
b. caramelization or pyrolysis of food carbohydrates due to heat treatment above the melting point of sugar under alkaline or acidic conditions.
c. browning of ascorbic acid: the thermal decomposition of ascorbic acid
d. lipid browning (rancidity), which is oxidation of lipids
e. reaction between the food and the packaging material
e. not changing frying oils - Enzymatic Browning - can occur when the apples, potatoes, and some other fruits and vegetables are cut and exposed to air
- enzymes present in the cells of food carry out an oxidation reaction, such as colorless compounds converted to brown-colored compound
- enzymatic browning does not occur in cooked fruits and vegetables since the enzymes are destroyed by heat
a chemical that can form naturally in starchy foods, like potatoes and grains, during high-temperature cooking processes such as frying, roasting, and baking, and is also found in cigarette smoke.
Acrylamide
How to prevent enzymatic browning
Treat fruits and vegetables with acids like lemon juice to prevent them from turning brown
Don’t soak in water because it will make them soggy
Examples of few polyphenol compounds
Quercetin
Myricetin
Caffeic acid
a condition characterized by excessive pigmentation of body surfaces due to the accumulation of melanin
Melanosis
Signs of microbial spoilage
- rotten egg smell from sulfur-producing microbes
- other off-odors from nitrogenous compounds, such as ammonia and amines
- sliminess from overgrowth of microbes
- gas formation and bubbling
- sponginess in meats
- greening from sulfide-producing bacteria
- rainbow sheen from fluorescent pseudomonads
- souring from acid production
- other off-tastes
Frozen meat microbial agents of concern
Cladosporium herbarum
Penicillium hirsutum
Cryptococcus
Trichosporon
Candida
Raw, comminuted meat microbial agents of concern
Gram-positive bacteria and LAB
Dried meat microbial agents of concern
Aspergillus glaucus
Raw, cured meat microbial agents of concern
Enterobacteriaceae
Clostridium
LAB
Cooked, uncured meat microbial agents of concern
Gram-negative psychrotrophic bacteria
LAB
Cooked, cured meat microbial agents of concern
Heat resistant psychrotrophs, Bacillus spp.
LAB
Frozen raw poultry microbial agents of concern
Cladosporium herbarum
Perishable, cooked poultry microbial agents of concern
LAB, Aeromonas spp.
Psychrotrophic clostridia
Chilled raw poultry microbial agents of concern
Psychrotrophic bacteria
Heat-processed or cured poultry microbial agents of concern
Psychrotrophic bacteria or molds, respectively
Irradiated poultry microbial agents of concern
Moraxella
Enterococci
LAB
Aerobic or anaerobic:
Surface spoilage
Aerobic
Aerobic or anaerobic:
Color
Aerobic
Aerobic or anaerobic:
Change in fat
Aerobic
Aerobic or anaerobic:
Surface color and spot
Aerobic
Aerobic or anaerobic:
Phosphorescence
Aerobic
Aerobic or anaerobic:
Whiskers
Aerobic
Aerobic or anaerobic:
Putrefaction
Anaerobic
Aerobic or anaerobic:
Gas production
Anaerobic
Aerobic or anaerobic:
Souring
Anaerobic
Aquaculture seafood microbial agents of concern
Pseudomonas
Acinetobacter
Frozen or chilled seafood microbial agents of concern
Pseudomonas
Acinetobacter
Pasteurized seafood microbial agents of concern
Spore-forming gram-positive bacteria
Clostridia
Freshly caught, iced >14 days seafood microbial agents of concern
Micrococcus
Bacillus
Staphylococcus
Pseudomonas
Processed - cured, canned seafood microbial agents of concern
Clostridium botulinum
A number of parasites can also be transmitted by seafoods, including:
- tapeworm Diphyllobothrium latum (in trout, pacific salmon, and perch)
- nematodes Anisakis simplex (occurring worldwide in a wide range of marine fish) and Capillaria philippinensis (in fish from fresh and brackish water)
- trematodes Clonorchis sinensis (especially in crabs), Opisthorchis (in fish), and Paragonimus (in crabs and fish).
A condition marked by a loss of more than 10% of body weight, including loss of muscle mass and fat, in a person who is not trying to lose weight.
Cachexia
Drugs used to treat infection causedby Capillaria philippinensis
Albendazole or mebendazole
Raw, minimally processed vegetables microbial agents of concern
Coliforms
Pseudomonas spp.
Clostridium spp.
Frozen vegetables microbial agents of concern
LAB
Enterococci
Micrococci
Canned vegetables microbial agents of concern
Clostridium botulinum
Fermented, acidified vegetables microbial agents of concern
Yeasts
Lactobacilli
Bacillus spp.
Sprouts vegetables microbial agents of concern
Enterobacter aerogenes
Mushrooms vegetables microbial agents of concern
Yeasts
Molds
Fruits microbial agents of concern
Penicillium
Aspergillus
Rhizopus
Saccharomyces
Milk and other dairy products microbial agents of concern
Pseudomonas
Eggs microbial agents of concern
Pseudomonas
Cereals and cereal products microbial agents of concern
Bacillus
Nuts and oilseeds microbial agents of concern
Molds
A ________ date is only required for foods with a shelf life of less than 90 days. You can buy and eat foods that are past the ——- date.
Year, month, day
Best before
Canned items are among the safest foods around and may be safe after five years or more if stored in a cool pantry
______ dates appear on medications, meal replacements (Boost) and liquid supplements (infant formula). Throw out the item if it is past this date.
Expiry date
If EXP isn’t there, then it is a best before date
Year, month
are printed on most foods to track product
Manufacturing codes
Administrative order?
Revised rules and regulations governing the labeling of prepacked food products further amending certain provisions and administrative order …
Administrative order no. 2014-0030
means the country in which the processing is performed shall be considered to be the country of origin for the purpose of labeling
Country of manufacture/Country of origin
refers to the relevant information regarding the constitution, preparation, and consumption of a food product
Directions/Instructions for use
means the date which signifies the end of the estimated period under any stated storage condition, after which the product will not have the quality attributes normally expected by the consumers. After this date, the food should not be regarded as marketable.
Expiry or Expiration Date/Use-by-date/Consume Before (Recommended last consumption date)
means any processed substance, which is intended for human consumption and includes drinks for human beings, beverages, chewing gum and any substance which have been used as an ingredient in the manufacture, preparation, or treatment of food
Food
means any substance not normally consumed as food by itself and not normally used as a typical ingredient of the food, whether or not it has nutritive value.
Food additive
in Administrative order 2014-0030
Day, month, year
01Jan12
refers to food safety, foods should not be eaten after that date
Use by
refers to food quality, foods can often be eaten after the date
Best before
