Food Preservation Flashcards
What are the aims of food preservation?
What are the internal characteristics of food that makes them prone to spoilage?
- Moisture
- pH (food naturally has a very conducive environment for microorganisms to grow).
- Temperature
4.
What is FAT TOM?
To avoid spoilage, we have to manipulate the FAT TOM.
Food preservation by changing the temperature of food to retard
growth of micro-organisms and inhibit enzyme activity
Boiling, cooking, ceiling in air tight containers, con fit (cook in fat or oil so it is now hidden in the oil), Gellatin (so it solidifies - cook to kill microbes and then solidify so no freely available water), stew, smoking.
Chilling and freezing kills bacteria.
When preserved in -20, microorganisms do not DIE but not dividing. When back in temp danger zone they start to divide again. Cooking kills, then pack it.
Confit, canning, geling, stewing is very important
How much nitrogen, oxygen, and CO2 are in environment?
Nitrogen = 78%
Oxygen = 21%
CO2 = 2%?
Went through numbers
Aerobic bacteria:
1. Pseudomonas
Like campyloabcter, listeria, etc. are facultative anerobes.
Anaerobic does not guarantee your food is safe.
? increase oygen level up to 85%.
Relisten to this slide
Moisture
We don’t want the free water in the food. We need to immediately eliminate it from the food. We do this by drying: either sand drying or other drying.
Salting or sugaring works too.
Freeze drying also works. Freezing makes water ice. Ice –> sublimation where the ice is directly converted into vapor.
potasium nitrate
sodium nitrate
sodium chloride
Nitrate and nitrite –> be careful. B/c they are toxic. they directly bind to hemoglobin or myoglobin and no more oxygen avaialble b/c compete with oxygen. If we consume intoxicated meat with this, our heart will be affected since myoglobin is taken up by nitrite.
pH is naturally in pH danger zone that support microorganisms to grow. We have to immerse our food in anoher pH so we convert them into alkaline or acidic.
Soak in sosdium hydroxide, so fish is in alkaline pH. Or can immerse your food in Vinegar whihc is acidic.
Beneficial bacteira produce acid. E.g. during hceese making we add bacteria intentionally, e.g cryptococcus.
Brine is a salt. Changes oH to remove freely availalbe water.
Are food additives legal? Technically it is adulteration b/c we, by law, can not add anything to food. But in 1973 it is actually allowed so long as it is beneficial.
Free radicals happen during aerobic respiration. –> rancidity
Must clean before attaching oxygen to our food. How do we clean off free radicals? Who consumes free radicals? antioxidants. vitamin C, vitamin E, citric acid, sulfide, and butanic chemicals like ? thye clean all free radiclals
Irradiation kills microorganisms. Xray, gmama ray, or electron beam. They are passing under beam. Wiht irradtuation, the micrororganisms die. People dont like this
10 kills microroganisms.
Electroporation –> allow food to ass throguh two electrodes. Makes poor then killed. Wildly used in US for preservation of potatoes.
relisten
Many hurdles put in place so microorganims have to jump but not reach us. But they still reach us! Hurdle technology is very good, but sometimes there is a failure somewhere.
Food preservation is really important.
