Lesson 6 Flashcards
What are viruses and how do they differ from bacteria in terms of visibility and reproduction?
Viruses are minute organic forms that are smaller than bacteria and can pass through the tiny pores of a porcelain filter that retains bacteria. They cannot be seen through a regular microscope but can be seen through an electron microscope. Unlike bacteria, viruses cannot reproduce in food and use human cells to duplicate themselves.
What are some common diseases caused by viruses?
Viruses cause diseases such as poliomyelitis, smallpox, measles, mumps, encephalitis, influenza, and the common cold.
How do viruses contaminate food, and what is a common cause of viral contamination in the food industry?
Viruses in food often indicate contamination through human feces, typically due to poor personal hygiene of food workers, such as not washing hands thoroughly after using the toilet. The two most common viruses in the food industry are Hepatitis A and Noroviruses.
What are the two most common viruses found in the food industry and what are their effects?
The two most common viruses in the food industry are Hepatitis A and Noroviruses. Noroviruses are highly contagious and can spread quickly, while Hepatitis A can be fatal as it affects the liver.
What are parasites and how do they differ from bacteria and viruses?
Parasites are organisms that live in or on other organisms without benefiting the host. They cannot live independently, unlike bacteria and viruses.
What are the two most common parasites in the food industry and what foods are they associated with?
The two most common parasites in the food industry are Trichinella spiralis, associated with pork, and the round Anisakid worm, associated with many species of fish.
What is a significant risk associated with eating raw marinated fish, and how can it be controlled?
Eating raw marinated fish such as sushi, sashimi, and ceviche poses a risk of illnesses like Anisakiasis. This illness can be controlled by freezing fish at minus 31°F for 15 hours.
What are yeasts and how do they grow?
Yeasts are one-celled organisms larger than bacteria, found everywhere, and require food, moisture, warmth, and air to grow. They need sugar but can convert starch into sugar.
How are yeasts used in the baking and wine industries?
In the baking industry, yeasts are used to ‘raise dough’ through the production of carbon dioxide. In wine production, yeasts produce alcohol, with carbon dioxide gas bubbling off and leaving the alcohol.
What is the maximum alcohol concentration that yeasts can produce, and why?
Yeasts can produce a maximum of 18% alcohol, as they are killed at this concentration.
How do yeasts reproduce and what methods are used to destroy them?
Yeasts reproduce by budding, similar to binary fission. Methods for destroying yeasts include those used for bacteria, such as heat and chemicals.
What are molds and how can they be identified?
Molds are multicellular microscopic plants that become visible when growing in sufficient quantity. Mold colonies have definite colors (white, black, green, etc.) and are larger than bacteria or yeasts.
Are molds generally harmful, and how are they used beneficially?
Some molds are pathogenic, causing diseases like athlete’s foot and ringworm, but moldy foods usually do not cause illness. Beneficial molds are used in certain cheeses to produce characteristic flavors and in the production of antibiotics like penicillin.
What is the structure of mold and how do molds reproduce?
Molds have a root-like structure called the mycelium, a stem called the hypha, and a spore sac called the sporangium. Molds reproduce by means of spores.
What conditions do molds require for growth?
Molds require moisture and air for growth and can grow on almost any organic matter. They do not require warmth and can grow well in refrigerators. They do not need much moisture, although they multiply better with more moisture.
