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Lecture020
MB351Exam3
| Question | Answer |
|---|---|
| What are the four types of Gastroenteritis viruses? | Rotavirus, adenovirus, norovirus, and astrovirus |
| Label the sizes of the viruses from smallest to largest. | noro, astro, adeno, rota |
| What are some factors that affect microbial growth in food? | Presence and availability of water; pH; and temperature |
| Why does water affect microbial growth in food? | Lower water activity inhibits microbial growth |
| Why does pH affect microbial growth in food? | It impacts make up of microbial community |
| Why does temp. affect microbial growth in food? | Lower temp. retard microbial growth, although psychrophiles will still grow in the refrigerator. |
| What is food spoilage? | It results from growth of microbes in food that alters food visibly and makes it unsuitable for consumption |
| What are some toxins that are sometimes produced from food spoilage? | algal toxins contaminate shellfish and finfish ergotism toxic condition caused by growth of fungus in grains |
| What is food preservation? | It is used to remove microorganisms usually by filtration |
| Why is food preservation better for food? | It changes the pH (pickling), it lowers the temp., canning (commercial foods) |
| Why is pastuerization good for food preservation? | It reduces number of spoilage organisms |
| Why is reducing water good for food preservation? | it is used to dry or freeze-dry food, also can add high concentrations of solutes such as sugar or salt to help better preserve food |
| What is lyophilization? | freeze-drying food to help better preserve it such as astronaut ice cream |
| What is a Chemical-based preservation? | It consists of microbial growth inhibitors such as sodium benzoate. Nitrite and ethylene oxide are more controversial. |
| What is nitrite in food preservation? | It is a carcinogenic precursor |
| What is ethylene oxide in food preservation? | It is a mutagen |
| Why is radiation important in food preservation? | It is UV radiation that is used for surfaces of food-handling equipment and does not penetrate food. |
| What causes Food-borne Infection? | Caused by ingestion of microbes, following growth, tissue invasion, and release of toxins |
| What microbes can cause food-borne illness? | Salmonella and campylobacter |
| What is Food-borne intoxications or food poisoning? | It is ingestion of toxins in foods in which microbes have grown. (Microbes that make the toxins do not have to grow in host.) |
| What are some other types of food poisoning food poisoning? | Staphylococcal food poisoning and botulism |
| What is Salmonella Spp? | It is a gram-negative, facultative, and rod shaped microbe. |
| What does Salmonella cause? | Food borne infection that causes gastoenteritis in 12-72 hrs after infection that can lead to septicemia. |
| What causes typhoid fever? | Salmonella typhi |
| What are the most common food sources that carry salmonella? | Meat and eggs |
| What is Staphylococcus aureus? | It is a gram-positive cocci that is part of a local flora. |
| Where does Staph. Coccus grow? | In many common foods, some strains make it heat stable enterotoxins (acts on intestinal wall). |
| What does Staph. aureus cause? | Food poisioning that comes from the toxin consumed in food, gastroenteritis occurs 1-6 hrs. |
| What are some food culprits of Staph. Coccus? | Cream bakery goods, meat, eggs, creamy dressings, puddings. |
| What is fermentation? | It is good food microbiology that consist of food that have been altered by microbial processes |
| What does fermentation consist of? | Anaerobic catabolism of organic cpds, generally carbohydrates and an organic metabolite (pyruvate or derivative) that is used as a final e- acceptor |
| What are some fermented foods? | Alcohol, bread, dairy products, meat, vegetables |
| What is alcohol produced from? | From fermentation by the yeast Saccharomyces cerevisiae |
| What are hops used in beer for? | It gives beer the bitterness and preserves it. |
| What microbe is used to make bread? | Saccharomyces cerevisiae |
| What is used to make beer? | Malted Barley, Saccharomyces cerevisiae (yeast) and hops |
| What microbe is used to make sourdough bread? | Saccharomyces exiguus and Lactobacillus sanfrancisco |
| What does lactic acid fermentation make? | Yogurt |
| What is split fermentation in yogurt production? | |
| What is Streptococcus thermophilus? | It is a THERMOPHILE that grows at 45 degrees or higher. |
| What does Strep. Thermophilus ferment? | It ferments lactose to lactic acid and the pH drops. Lactic acid them denatures casein to form a curd. |
| What are Lactobacillus bulgaricus and Lactobacillus acidophilus? | They are MESOPHILES that grow as the temperature falls into mesophillic range. |
| What do the two Lactobacillus ferment? | They ferment the remaining lactose and the yogurt flavor develops at this point. |
| Summarize the steps to make yogurt along with the the order of the three microbes. | |
| How is cheese made? | |
| How is cheese flavoring impacted? | Depends on the type of microbes used, time of ripening, and temp. of process that gives the cheese its flavor. |
| How are hard cheeses ripened? | By lactic acid bacteria growing anaerobically in the interior of the curd. |
| The growth of microbes in cheese is called what? | Ripening |
| How are semisoft cheese ripened? | By the mold penicillium on the surface. Some examples are: Stilton, Roquefort, Camembert |
| Why are cheese compressed into blocks? | To extend ripening. The longer the ripening period, the more acidic (sharper) the cheese. |
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kzxiong
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