Lecture 9 & 10 Week 5 - Meat Spoilage Flashcards
What is spoilage?
Degradation of food such that the food becomes unfit for human consumption.
What 4 things may characterise spoiled food?
- Increase in bacterial count
- Unacceptable flavours
- Unacceptable odours
- Undesirable appearance
What is shelf life?
The period of time in which a product is available and can be stored before it spoils.
What 3 things influence shelf-life? + what contributes to these 3 things (sub-category of each)?
- Storage environment - moisture, temp, lighting, packaging
- Muscle tissue factors - pH, muscle fibre types
- Micro-organism type & level
What 3 characteristics increase in meat that has spoiled?
- Putrefaction - breakdown of protein –> SLIME
- Sourness - increased lactic acid –> DISCOLOURATION
- Rancidity - breakdown of fats
What 2 characteristics increase in food/meat poisoning?
- Infection
2. Intoxication
What 5 things are responsible for food spoilage?
- Micro-organisms e.g. bacteria, fungi
- Enzymes
- Chemicals (produced by enzymes)
- Access through biological barrier e.g. splitting crustacean’s shells
- Extrinsic factors e.g. temp, packaging
Microorganisms are one of the 5 things responsible for causing food spoilage. What are 6 sources of microorganisms?
- Contamination
- Water/moisture - high water = high bacterial proliferation
- Equipment
- Air & dust
- Poor sanitation e.g. water not hot enough
- Bad technique
Enzymes are one of the 5 things responsible for causing food spoilage. How do they provide a welcoming environment for microorganisms? How can this be corrected?
- They breakdown the meat’s structure
- During ageing increased proteinaceous fluid therefore released
- This increased moisture provides a welcoming environment for microorganisms
- Can be corrected by adding anti-microbial absorption pads to packaging
Chemicals are one of the 5 things responsible for causing food spoilage. How does this occur on the meats EXTERIOR & INTERIOR? How can this be corrected?
EXTERIOR
- Oxidation of fat —> rancidity
- Oxidation of muscle —> change in meat colour
- Can be corrected by addition/increased antioxidants as they take up the binding spots of O2 on the meat resulting in decreased oxidation.
INTERIOR
- Acidity, mineral content & moisture content of the meat are influential on the number of microbes that exist.
Extrinsic factors (e.g. TEMPERATURE) are one of the 5 things responsible for causing food spoilage. How do they provide a welcoming environment for microorganisms? How can this be corrected?
Reducing refrigeration reduces bacterial growth. Meat should be stored at 3-4°C.
What are the 3 different categories of microbe in terms of temperature?
- Psychrotrophs: -10-30°C
- Mesophiles: 25-45°C - adjusted to body temp
- Thermophiles: 45->65°C
Extrinsic factors (e.g. PACKAGING) are one of the 5 things responsible for causing food spoilage. What causes this? How can this be corrected?
- Aerobic vs. anaerobic conditions (decreased colour change & smells)
- Types of gases e.g. non-specific, MAP, CO2
- ** Affects the extent to which oxygen can react with the meat, therefore influencing the meat’s colour
What are the 3 different types of myoglobin?
- Oxymyoglobin
- Metmyoglobin (low —> 1%)
- Deoxymyoglobin
What are two features consequential of seafood putrefaction?
- DISCOLOURATION
- Increased ALCALIGENES (off smells)
* ** This means changes in colour & smell are the best ways to detect seafood spoilage
