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41 Cards in this Set
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Trichinella spiralis 踹K妮辣 螺旋李斯 |
-Round worm that primarily infects wild and domestic animals, especially pigs(pork: most common source) -humans contract trichinosis by consumption of raw or undercooked pork -Pigs get infected by ingestion of raw or undercooked scraps of pork -图片，trichinella spiralis in the muscle fiber. Larve of parasite.
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Life cycle of Trichinella spiralis旋毛虫 |
-upon ingestion of pork infected with T. spiralis larvae, the encysted larvae are liberated(释放) from the cystin胱氨酸 the intestine, where they mature. -the mature female and male worms copulate(交媾) in the intestin, giving rise to a new generation of larvae. -the newly born larvae migrate to the various tissues of the body -Larvae reaching the striated muscles penetrate the sarcolemma(肌纤维膜)of muscle fibers, get encysted, and mature -也可进入muscle of heart/sarcolemma -在胃中释放，在小肠里成熟。Lymph/Tissue/brain |
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Trichinella spiralis: Disease and Control |
-Initial phase: Abdominal pain, nausea, vomiting, and diarrhea -Systemic phase: periorbital edema眶骨膜 瘤腺体，eosinophilia嗜酸性粒细胞增多症，myalgia肌痛，difficulty in breathing, and weakness -病症持续3月 -adequate cooking of pork -Freezing at -15℃ for 30 days, or at -35℃ -Avoid feeding garbage containing infected pork to swine |
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Anisakis爱你撒kis |
-nematode线虫，aquatic environment -Anisakiasis 异尖线虫病 in humans os caused by two foodborne round worms 1-Anisakis simplex爱你亲你 多简单(definitive host is whale) 2-Pseudoterranova 假性特然弄娃decipiens 得死屁死(definitive host is seals) |
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Anisakis: Life cycle |
-eggs in feces -eggs undergo molting 脱毛，换毛 in intermediate hosts, develop into larvae -Larvae are eaten by fish -human get anisakiasis by eating fish |
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Anisakis:Disease and Control |
-Non-invasive anisakiasis, worms released from ingested fish migrate to pharynx(发如你可是)， resulting in "tingling throat麻刺感喉咙". The worms are finally expelled by coughing -In invasive anisakiasis, worms penetrate the intestinal mucosa, and cause symptoms such as stomach pain, nausea, vomiting, and diarrhea -adequate cooking of fish -Freezing of fish at -23℃ for 7days |
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Taenia species |
-Tapeworm(flatworm) -Taenia solium(搜恋pork)，eggs develop into embryos in duodenum(多低能，十二指肠),penetrate the intestine membrane, migrate to skeletal muscles and myocardium(心肌), Cysticercus cellulosae(猪囊尾蚴), 人类还是吃了，在小肠里变成 worms, 粪便排出， Symptoms :anorexia, nervousness(神经质，神经过敏)， insomia(失眠)，大部分还是肠道类疾病 -Taenia saginata(撒基拿他，beef)， eggs survive in pastures(牧草)，ingested buy cattle. In cattle, eggs hatch into embryos, migrate to skeletal muscles, or heart, and develop into larvae called "Cysticercus bovis牛囊尾蚴"，human gets infected by ingesting undercook beef. In humans, larvae released in intestine and mature in to adult worms, excrete the worms or eggs in feces, Symptoms of Taenia:anorexia神经性厌食，headache， dizziness, diarrhea, and weight loss
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Diphyllobothrium 带肥萝不死人latum辣疼: Life cycle |
-Largest human tapeworms(Main source: fish) -Human get diphyllobothriasis by larvae form, plerocercoids(全尾蚴)破烂弱色空已死 -upon ingestion,依旧在小肠里成熟 -在粪便里排出 -in feces containinf water, free swimming larvae called "Coricidia扣瑞死大" |
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Diphyllobothrium latum: Life cycle |
-Coricidia are ingested by crustaceans(甲壳类动物)，juvenile stage→ procercoids(原尾蚴) -Fish ingest crustaceans, plerocercoids -symptoms include abdominal pain, diarrhea, weakness, and pernicious anemia(有害的，恶性的贫血症):Vitamin B12 deficiency |
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Diphyllobothrium latum: Life cycle and Control |
human(eggs)→Coricidia(larvae, water,free swimming)→procercoid(juvenile stage in crustaceans)→fish(plerocercoids)→ mature in humans -cook and freezing -treatment: antibiotics |
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Food preservation objectives and how |
objectives -Extend/maintain bacterial cells in lag phase -prevent bacteria from entering log phase -inactive bacteria(cook can) How -keep microorganisms out of food -remove microorganisms -prevent/delay growth of microorganims: chilling, freezing, acidification, drying, gaseous environment -Kill/destroy microorganisms: heating , radiation, acidification |
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Type of low tem storage |
1 cellar storage(fresh produced) 15℃, 苹果，西红柿，胡萝卜，Mold growth is a problem 2 chilling or refrigeration 0-5(meats, dairy foods, eggs, seafoods)除了food with low aw -metabolic reactions become slower -cold: cell membrane rigid, and break, so bac will make more unsaturated lipids in membrane -more polysaccharidez, pigments, enzymes, 例子，more slimes and capsules to respond to cold temperature. Pseudomonas growing in milk at 4℃, make more protease. 3 freezing less than -18℃ or 0F arrests growth of microorganisms May injure /kill some完全停止细菌的生长 microorganisms，不会杀死细菌 -No metabolic activity -Dehydration effects: less water in tje cells -concentration of solute→toxicity of intracellular solutes -internal and external crystals formation and damage -Gram positive bac are more resistant than Gram-neg (outer membrane property) -spores are more resistant to freezing |
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Freezing |
-Freezing is more detrimental to bac in foods with low ph than foods with neural ph -cryoprotectants(glycerol, milk protein, egg albumen) can decreas the harmful effects on bac -Rapid thawing decrease the lethal efffects of freezing on bac -Slow thawing more harmful to bac, but bettet for food safety. |
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Preservation of food by high temperature |
1-Pastreurization -Hig Tem Short time 72℃ for 15sec -Low Tem Long Time 63℃ for 30minutes -Ultra High Tem -138℃ for 2 sec the above treatments are sufficient to destroy Mybobacterium tuberculosis(most heat resistant ) we have different stain for MB Ziehl-Neelsen宰哦尼森 stain Coxiella 叩谢啦 burnetii不能踢(Q fever) similar to Rickettsia 2-Sterilizaition -Destruction of all viable microorganisms -employed ib canning
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Factors affecting heat resistance of microorganims |
-Water heat resistance increase with low aw protein denature fast in present of water, 有水，allow thermal breaking of peptide bonds. 无水，需要更多的energy -Fat heat resistance increase with prsence of fat: fat protection long chaim are better protectors -Salt varies with kind of salts, concentration of salts salt with low aw of foods make more heat resistant -碳水化合物Carbohydrate more Carbohydrate, more resistance. Low aw. Sucrose, glucose, sorbital, fructose, glycerol SGSFG -pH neutrol pH, most resistant to heat -Proteins protect microorganisms -number of microorganims larger number, more protection, many extravellular components are protein in nature. -age of mo stationary phase: most resistant to heat, log phase: least resistant to heat : least resistant to heat -Growth tem Psychrophilic驱冷菌， mesophiles, thermophiles - spore form - Gram-positive - cocci - Yeasts and molds fairly 一样的heat sensitive -spores than vegetative cells 1 Protoplast dehydration 2 Mineralization 3 presence of dipicolinic acid 滴屁扣丽你卡 4 small acid-solube proteins -inhibitory compounds anti,nitrites decrease heatresistance
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D-value |
-time required for destroy 90％ of mo at a given tem -12D: 12log comcept heat treatment to insure 12 log reduction
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Food preservation by irradiation |
-Ultral 240-280 lethal mutation on nucleic acid poor penetrative ability surface Gram neg, easilly killed Spores, molds and voruses are more resistant -beta stream of electrons from a radioctive substance -poor penetrative ability -gamma eletromagnetic radiations emitted from excited nucleus of elements like 60Co 137Cs excellent penetration -cheaper -X-ray produced by the bombardment of heavy metal targets with high velocity electrons (cathode rays)贵 -Microwaves: heating, reheating, not a private preservation
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Classification of radiation |
1-radappertization人大破太贼心 high dose treatment of foods with high doses of ionizing radiation(30 to 40kGy) used for preparing commercially sterile foods 2-Radacidation: medium dose 2.5-10kGy used for reducing the number of viable, non-sporing pathogenic mo(other than viruses) some timw equivalent to pastreurization 3-radurization: lower dose -reduce viable population of specific mo - used to enhance the keeping quality of foods 0.750-2.5 kGy |
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Mechanisms of lethal effects of radiations |
-damage of DNA -caused by radiation. .H or .OH -.OH 90％ of DNA -single strand DNA or DSB -most bac can repair single-strand break, but not DSB 3H2O→.H ＋.OH +H2+H2O2 -Gram negative, more sensitive |
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Type of mo can affecting efficiencty of radiation for killing mo |
-type of mo Gram neg, more sensitive Spore, more resistant Bac→Yeasts→molds→viruses -composition of medium or foods more complex the medium or foods, lesser effects of radiation(due to binding radicals by food constitutes) -Moisture content lesser moistur,lesser radiation effects(due to lesser formation of water radicals) -Tem mo are more resistant to radiation at subfreezing tem than ambient周围的 due to low water activity 高温下radiation很有效，repair enzyme are inactive at high tem -presence or absence of oxygen 无氧， radiation 变弱 |
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Limitation of radiation |
1-adverse effects on sensory qualities of foods, off flavor, off odors, undesirable color(myoglobin) 2-loss of nutrients 3-expensive 4-consumer fear and acceptances |
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Preservation of foods with chemicals |
-GRAS chemicals surface application used as an ingrediant -Safety -Efficacy -Quality effects -cost and practically
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Organic acids |
1 naturally present, bac fermentation, add as a preservation agent - Lactic acid:Lactobacillus, Lactococcus, Streptococcus, Pediococcus. CHO in lactic acids in cheese, yogurt, sauerkraut, pickles, olives, fermented meat. - Propionic acid : propionibacterium shermani, flavor and inhibitor in Swiss cheese -Malic acid(apples, grapes), citric acid(citrus fruits), tartaric acid(grapes), fumaric acid(plants), Succinic acid(plant and animal tissues) , Succinic acid(plant and animal tissues) |
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Mechanism of action of organic acids |
-lower pH of cytoplasm -pH=7, continue to lower, mo die -metabolic activity become standstill and stop, and mo die. -interfere with chemical transport across the membrane, and interfere with enzymatic activity -only RCOOH can enter the cell because of its charge -RCOOH become RCOO- H+ inside cell - Cell pump out + by using ATP - Run out of ATP, cytoplasm get acidified , cell die |
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Sodium benzoate |
-Sodium benzoate: first -在低pH下，工作的好，Neutral pH 无用 -apple cider, soft drink, tomato ketchup, salad dressing -higher level cause distaste
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Sorbic acid |
-Ca, Na, K salts of sorbic acid -below pH=6.0, above 6.5, 无用 -Primarily effective against molds and yeasts, but also effective on bac -fungistat in cheese, bread, fruit juices, beverage, salad dressing -In molds, sorbates inhibit the dehydrogenase enzyme system and prevent germination of spores to vegetative cells -in Bac, causes membrane disruption, and interfere with amino acid transport. |
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Propionic acid |
-Ca, Na salts of propionic acid are used permitted in breads, cakes, certain cheese -mold inhibitor -more effective at low pH, and ineffective above 6.5. |
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Nitrate and Nitrites(very potent antimiacrobial) |
-NaNO2, NaNO3 used on cured meats -flavor, stabilize the meat color. -NO2(Nitrite)→nitrious acid→NO(nitric oxide) -NO +Mb →Nitrosomyoglobin(desirable red color) -inhibit spoilage and pathogenic bacteria -antimicrobial effect of nitrites increases at low pH -Nitrite: Clostridium botulinum. iron-sulfur enzymes, ferredoxin, thus preventing the synthesis of pyruvate, thus spore germination is inhibited. . -对lactic acid bacteria 无效，因为无catalase, cytochromes.-used in cheese to control gassiness of C.butyricum C.tryobutyricum .-used in cheese to control gassiness of C.butyricum C.tryobutyricum -used in cheese to control gassiness of C.butyricum C.tryobutyricum - 120ppm is required in bacon, cured ham -secondary amine→nitroamine,carcinogenic -isoascorbate爱搜爱死锅背她inhibit
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Perservation of food with micro |
-Biopreservation |
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Hydrogen peroxide |
-oxidizing agent -cheese, starch -sterilize food packaging -instable in food product -singlet or superoxide oxygen -oxidation of sulfhydryl groups and double bonds- in proteins and lipids |
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Indirect antimicrobial |
-primary effects are not antimicro -antioxidants(reduce rancidity) Lipase(to prevent auto-oxidation of lipids(Butylated hydroxyanisole BHA, Butylated hydroxytoluene BHT, Butylhydroxyquinoline TBHQ) -Gram positive are more sensitive flavoring, emulsifying agent(keep solution as one) |
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Flavor agent |
-more antifungal than antibacterial -lactic acid bac are resistant -Diacetyl(More effective to Gram megative , prevent arginine utilization by reacting with arginine binding proteins), 2,3-pentabedione, menthol |
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Emulsifying agents |
-medium chain fatty acids and esters are used -work on Gram positive and yeasts -Caprylic Acid, Capric acid, monoester of glycerol acid(monolaurin, more effective in low pH) diester of sucrose(sucrose dicaprylate苏糖 带卡不儒莱特) |
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Protective Culture |
-improving safety of the product without changing the sensory characteristics of the food -Microguard, a growth extract from P. freudenreichii夫人等瑞吃， bacteriocins and diacetyl. |
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Probiotic cultures(Nutraceuticals营养食品) |
-human intestinal tract -Lactobacillus acidophilus 1稳固肠道微生物群 2 还原serum cholesterol 3 帮助乳糖吸收 4 V 合成 5 减少nitroamine 6 帮助钙的吸收 7 灭菌 8 帮助免疫系统 9 对宝宝的营养很关键 Lactobacillus 乳酸棒装杆菌acidophilus 嗜酸菌 Bifidobacterium避风都 longum龙哥 |
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Bacteriocins |
-bacterial proteins with narrow activities -adsorption to specific cell envelop receptors -Nicin(L lactis) 多肽，34氨基酸 针对Gram positive, 尤其是Spore forming -Reuterine(L reuteri) 对positive和negative都有用 失活ribonucleotife reductase -Natamycin(Primaricin) Streptomyces natalensis 对molds和yeast有用，对bac无用 -Lactacin(L acidophilus 88) -Lactocin S(Lactobacillus sake L45) -Plantaracin A(L plantarum C11) |
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Bacteriocins or antibiotics的要求 |
1 自然菌无抑制 2 在小肠内，inactive 3 可以被烹饪杀死 4 不会产生resistant 5 不会被食物失活 |
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益生菌的选择 |
1 normal biota 2 adhere the intestine mucosa 3 overcome low pH in stomach 4 tolerate bile acid 5 compete with other normal gut bac |
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Basis for stress tolerance |
1 heat shock proteins 2 general stress protection system rpoS gene 3 Acid resistance systems that include arginine decarboxylase system and glutamate decarboxylase in E.coli O157H7 |
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competitive exclusion |
salmonella, Campylobacter jejuni in Chicken, E.coli O157,H7 in cattle. |
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Exam Results |
Average: 84 High: 99 Low: 46 My scores: 96 |
