As well as killing spoilage microbes, blanching also inactivates these enzymes, preventing or arresting oxidation. Microorganisms Are Everywhere The bacteria, molds and yeasts that cause spoilage in plant foods need water and nutrients to grow and reproduce. Excess Moisture Invites Rot If you wash produce and store it wet, you make it even more inviting to spoilage bacteria.
Temperature Extremes Promote Decay Because extremes of hot and cold accelerate spoilage, fruits and veggies stay fresh longest when stored at cool temperatures. Oxygen Exposure Hastens Decomposition If you've noticed how quickly the flesh of an apple turns brown after being exposed to air, you've seen oxidation in action.
Factors that Affect the Quality of Food. How Does Food Decompose? How to Store Peeled Potatoes Overnight. Best Way to Store Broccoli. Instead, other bacteria species called pathogenic bacteria are the cause of foodborne illnesses like salmonella and E. It's possible for food to look and smell safe, but still contain dangerous levels of pathogenic bacteria. Improper food storage is a leading cause of spoilage.
If your house is warm and humid, fruits and veggies left in the open will spoil quickly. A refrigerator temperature above 40 F allows for the growth of spoilage bacteria. Food items should be stored separately in tightly sealed containers.
Designate one drawer for meats, one for cheeses and one for vegetables. Check your refrigerator foods every day.
If one food starts to spoil, remove it immediately. The spoilage bacteria may spread from the bad food and contaminate everything else. Refrigerators set below 40 F will prevent pathogenic bacteria from growing freely. However, refrigerators generally aren't cold enough to stop all bacterial growth. Many biological reactions will speed up in warm temperatures and slow down in cold temperatures. Availability of water: Decomposers need water to survive and reproduce.
Chemical composition of food: the higher the nitrogen to carbon ratio the quicker organic matter will rot because decomposers can get more energy from nitrogen. Objectives Differentiate between compostable waste and non-biodegradable waste. Materials sealed bags of rotting fruit, vegetables or bread that decay at different rates Allow rotting food 2—10 days to begin decomposing. What To Do Set up Pass around the examples of rotting and not rotting products and discuss what affects the rate of rotting.
Make sure any bags containing rotting materials are sealed tight. Hand out all the pictures of waste to students. Challenge Put them in order of fastest to slowest to degrade. And watching the Inuit fish under thick ice gave Clarence Birdseye the idea of fast-freezing food; this creates smaller ice crystals than ordinary freezing, resulting in less damage to cell walls, so the food not only keeps for longer but also tastes better.
Beginning with communities in hotter regions like the Middle East, dried food has been around for thousands of years — the earliest cases are thought to date back to 12,BC. Drying food, whether using the sun and wind or modern factory processes, removes water from the cells of the microbes that break down food. This stops them reproducing and ultimately kills them. An extension of this is the use of salt or sugar to preserve food. In the Middle Ages, salted fish like herring and cod were widely eaten in northern Europe, and fish was of course essential during Lent.
The cells of microorganisms have walls that are permeable to water but not to salt. When the cell is in contact with salt, osmosis takes place, so water moves out of the cell in order to try to equalise the salt concentration inside and outside the cell, and eventually so much water is removed from the cell that it dies. No more bacteria. Sugar has a similar effect, just think of fruit preserves, jam or jellies. Smoking also dries out food.
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