14 Food Microbiology
Microbial Preservation of Food
Microbial Activity:
Lowers pH in products like silage and yogurt to inhibit growth of undesirable organisms.
Example: Lactobacillus prevents Clostridium botulinum toxin formation, enhancing safety in fermented products.
Purposes of Food Preservation:
Prevent pathogen growth and limit toxic by-products.
Reduce spoilage and extend shelf life.
Traditional Food Preservation Techniques
Salting:
Meats and vegetables are treated to kill microbes through osmotic effect.
Drying:
Sunlight exposure helps reduce water activity, inhibiting microbial growth.
Smoking:
Adds chemicals (phenolics, formaldehyde) that have antimicrobial and antioxidant properties.
Canning:
Involves heating, sterilizing, and sealing in containers.
Variable processes based on specific foods, ensuring sterility and quality control.
Critical factors: Endospore inactivation and thermal death time for pathogens.
Historical Context of Food Canning
Originated with Napoleon's efforts to nourish the army.
Gained popularity in the mid-19th century; issues like lead poisoning from soldered cans arose.
Prominent Technologies:
Temperature treatments developed over time, including:
Pasturisation.
High-Temperature Short Time (HTST).
Ultra-High Temperature (UHT) methods.
Use of Food Preservatives
Purpose:
Prevent pathogen growth (e.g., Clostridium, Staphylococcus).
Combat spoilage organisms (e.g., bread mould).
Examples of Preservatives:
Natural additives (E290 - CO2, E260 - Acetic acid, E270 - Lactic acid).
Food Irradiation as Preservation Method
Function:
Reduces microbial load, insect contaminants, and inhibits sprouting.
Safety:
Approved by WHO, FAO; may affect vitamins but not macronutrients.
Questions
name 2 traditional preservation techniques
What are fomites?
Who invented the process of canning?
What role plays water activity in food preservation?