Food Chains, Production Methods, and Preservation Techniques
The Food Chain Structure
The food chain describes the transfer of energy between organisms. It is typically divided into three main links:
First Link: Producing Organisms (Autotrophs)
These organisms, primarily vegetables, are autotrophs, meaning they produce their own food.
Second Link: Consumer Organisms (Heterotrophs)
These are heterotrophic beings that consume other organisms. They are categorized by their diet:
- Primary Consumers: Herbivores.
- Secondary Consumers: Such as reptiles or fish, which consume primary consumers.
- Tertiary Consumers: Organisms (like humans) whose food source is secondary consumers.
Last Link: Decomposers
Formed by organisms such as bacteria and fungi, decomposers are responsible for degrading organic matter, transforming it into inorganic substances.
Global Food Sources and Production Methods
In the eighteenth century, a rapid increase in population implied a major and growing need for food. This demand has driven several key developments in food production:
Increased Agricultural Production (The Green Revolution)
This involves the utilization of genetically engineered plants and improved farming techniques, often referred to as the Green Revolution.
Intensive Livestock Farming
Achieved through housing and feeding animals specialized feed meals made from grain, which possess excellent nutritional properties.
Greater Use of Marine Resources (Aquaculture)
Aquaculture is the practice of producing living matter in an aquatic environment to meet food demands.
Negative Impacts of Intensive Food Production
Environmental Pollution from Agrochemicals
Agrochemicals pollute the environment when they reach rivers or seep through the soil to reach groundwater.
Concerns Regarding Transgenic Organisms
While genetically modified organisms (GMOs) can be resistant to cold or pests and offer better nutrition, their long-term effects are often debated.
Risks Associated with Feedlot Cattle Feeding
Intensive feeding increases the animal’s growth rate. Substances like clenbuterol, which is banned, can cause poisoning in people who ingest contaminated meat. Another serious issue is the outbreak of Mad Cow Disease (Bovine Spongiform Encephalopathy), which causes irreversible damage to the nervous system and can lead to death.
Infected Fish and Parasites
Fish can be infected with a worm parasite, the Anisakis, which can produce a severe and lasting allergic reaction in humans.
Food Contamination and Deterioration
Food quality can be compromised by various factors:
Types of Contamination
- Biological Contamination: Caused by living agents such as viruses, bacteria, and fungi.
- Chemical Contamination: Caused by chemical substances that can lead to poisoning.
Food Degradation
This is caused by enzymes present in the food itself, which accelerate the decomposition process.
Foodborne Diseases
Diseases transmitted through contaminated food include:
- Parasitic Diseases: Such as trichinosis.
- Infectious Diseases: Such as cholera.
- Toxic Diseases: Such as botulism.
Essential Methods of Food Preservation
Various techniques are employed to extend the shelf life of food and prevent spoilage:
Preservation Using Cold
- Chilling: Storage temperatures maintained between 0°C and 6°C.
- Freezing: Temperatures below freezing (e.g., -30°C) used for rapid freezing.
- Deep Freezing: Long-term preservation typically maintained between -18°C and -20°C.
Preservation by Radiation
Used to prevent the sprouting of potato roots or delay the ripening of fruit.
Preservation by Heat Destruction
Pasteurization
Uses temperatures between 70°C and 90°C for a few seconds. This process destroys yeast, molds, and most bacteria.
Sterilization
Applies temperatures above 110°C for a longer duration than pasteurization. It destroys all types of microorganisms. A drawback is the potential for flavor change and vitamin loss.
Preservation by Water Loss (Dehydration)
- Drying: Food is exposed to the action of sunlight or airflow to remove moisture.
- Salting: The addition of salt causes a corresponding decrease in the water content of the food, inhibiting microbial growth.
Other Preservation Methods
- Smoking: Conservation achieved through the desiccant action of smoke and the antiseptic power of heat.
- Pickling: Subjecting food to the action of vinegar (acetic acid).
- Marinating: A process where food is left to macerate in an aqueous solution often containing garlic, pepper, and salt.
- Curing: Steeping food to prevent the action of enzymes and microorganisms.
- Preservation in Alcoholic Liquid or Sugars: Used for products like marmalades and jams.
- Packaging Methods: Includes packaging with gas, vacuum sealing, canning, or bottling.