Food Science and Biotechnology

Biotechnology II

COMPETENCY: 13.00

Examine techniques and biological processes in food

science related to biotechnology.

OBJECTIVE: 13.01 Explore food borne pathogens and

spoilage organisms in relation to agricultural biotechnology.

Common Food Bourne Pathogens 1. Salmonella enteriditus

A common bacteria responsible for severe cases of food poisoning and digestive ailments in humans.

Often transmitted through contact with infected animals or ingestion of raw or undercooked egg that has contacted a contaminated shell.

2. Campylobacter jejuni Common bacterial pathogen found in undercooked

meats, unpasteurized milk, and other contaminated foods.

Responsible for more than 10% of all instances of diarrhea in the US.

Salmonella enteriditus

Source: http://www.magma.ca/~pavel/science/Salmonella.htm

Campylobacter jejuni

Scanning electron microscope image of Campylobacter jejuni, illustrating its corkscrew appearance and bipolar flagella. Source: Virginia-Maryland Regional College of Veterinary Medicine, Blacksburg, Virginia.

Common Food Bourne Pathogens 3. Bacterial contaminants usually spread by

physical contact or ingestion of a contaminated liquid or solid.

4. Fungi A variety of fungi are used in the production of

foods, including cheeses and yogurt. Other fungi are contaminants, some even toxic.

Often appear on breads with high moisture and sugar content, citrus fruits and grains.

Usually spread by airborne spores as opposed. Often appear as fuzzy, blue growth in canned corn or

fuzzy, white spots on bread.

Preventing Food Bourne Pathogens 1. Poultry & Other Meats

Meat should be heated in an oven to 74°C for at least 15 seconds.

2. The optimal temperature range for the growth of harmful bacteria in foods is between 4°C – 60°C. Low temperatures usually cause dormancy in

bacteria. High temperatures can deactivate or even destroy

bacteria.

OBJECTIVE: 13.02 Summarize enzyme activities and

fermentation processes that are useful in the food processing industry.

Enzyme Activities 1. Enzymes are specialized proteins that act

as catalysts to speed up chemical reactions in organisms or compounds. Enzymes are incredibly important in processes as

diverse as digestion, respiration, and fermentation.

It is enzymes that convert lactose in milk during the process of making yogurt that allows lactose intolerant people to consume the product.

2. There are 26 enzymes almost always ending in the suffix “ase”. Important enzymes include amylase, protease,

and lipase.

Fermentation Processes 1. Fermentation- the anaerobic conversion of

sugars in plant materials to simple chemical compounds. Alcoholic fermentation the most common and

important in biotechnology. The conversion of sugars during the breaking down

of plant materials into Carbon Dioxide and Ethanol. Carried out by yeast.

2. The study of fermentation processes used in bread making, wine making and the formation of other food products is known as Zymology.

Yeast Important microorganisms in the

production of several types of foods. Yeast are NOT BACTERIA- but fungi.

pH and temperature are important for the function of yeast in fermentation and other processes, as high temps or extreme ph levels will kill the microorganisms.

OBJECTIVE: 13.03 Discuss the impact of genetic

engineering on food preservation, food quality and nutritional value.

Potential Applications of Biotechnology in Food Science1. Crops and animals can be genetically

engineered to: Survive drought and other harsh local conditions. Last many times longer in storage than normal

variations. Ex- The removal of genes coding for the production

of ethylene in fruit code greatly prolong shelf life by preventing decay.

Possess increased nutritional value to address vitamin or energy absences in the diets of a population.

Golden Rice and other crops designed to address nutritional deficiencies often used genes from microorganisms or animals in plants to produce more vitamins or other beneficial compounds.

Potential Applications of Biotechnology in Food Science

Exhibit insect resistance, negating the need for the use of pesticides that can leave toxic residues on crops.

Successful use of biotechnology insect controls like Bt have not only reduced insect damage to crops without the use of pesticides, but also reduced the occurrence of fungal damage during long term crop storage.

(1) Fungal pathogens often occur in the wounds or around the waste of plant insect pests.

Remove negative substances found in plant or animal products:

Ex: The removal of caffeine from coffee beans.

Potential Applications of Biotechnology in Food Science

2. Biotechnology can be used to simplify the production of foods, decreasing environmental strain and impacts. The enzyme rennin, used to make cheese,

once had to be collected from the digestive system of cattle.

Rennin is now produced in unlimited quantities in genetically engineered bacteria, requiring little energy, care or processing.

OBJECTIVE: 13.04 Demonstrate proper food

preservation and sterilization techniques.

Food Preservation Techniques 1. Freezing- the placement of a food

product in subzero temperatures. Increases the shelf life of many foods

indefinitely with varying impacts on food quality.

Will NOT KILL most common bacteria (Salmonella, Listeria etc) only make them dormant.

Most foods should not be refrozen after thawing.

Food Preservation Techniques2. Irradiation- the treatment of food

products with low levels of ionizing radiation to kill microorganisms in food. IS NOT DANGEROUS FOR HUMAN

CONSUMPTION. Does not alter food quality and taste, and

is in fact, the least invasive method of sterilization for many food products including meats.

Food Preservation Techniques3. Dehydration / Salting- preservation

methods dependent on the removal of water from food products, providing an inhospitable environment for microorganisms. Highly effective for meats and many other foods,

but changes taste and texture drastically. Used throughout history- the only effective

method of storing food through much of ancient history.

Food Preservation Techniques4. Pickling- utilizes a vinegar-based

solution to soak foods, creating an environment in which bacteria may not survive. Effective, but drastically alters taste. Environment must be acidic enough to be

effective.

Food Preservation Techniques5. Steam Sterilization- utilizes super

heated water to kill surface bacteria. Often used in the processing of meats.

Food Preservation Techniques6. Oven / Microwave

Physically cooking foods to proper internal temperatures ensures the destruction of harmful bacteria.

This is the reason most restaurants will not serve rare hamburger.

Indicators of Food Safety 1. Food containers and process are

specifically designed to ensure food safety. The presence of a raised center on the lid of home

canned vegetables or store purchased foods indicates likely bacterial contamination.

Botulism is an example of a toxic bacteria often occurring in such instances.

Abnormal visual growths or smells are often an indication of the presence of bacterial or fungal contamination.

Many contaminants are NOT readily recognizable.