The first high school biology lesson on winemaking is elective several

High School Biology Elective 1 Biotechnology Practice Knowledge Points Summary Topic 1 Application of Traditional Fermentation Techniques Topic 1 Production of Fruit Wine and Fruit Vinegar I. Fermentation: the process of producing large quantities of metabolites through the cultivation of microbial techniques. Aerobic fermentation: acetic acid fermentation Glutamic acid fermentation - Anaerobic fermentation: alcoholic fermentation Lactic acid fermentation III. Yeast is a parthenogenetic anaerobic bacterial microbial fungus - Reproductive modes of yeast: emergent reproduction (mainly) schizogony Sporulation IV. Under aerobic conditions, yeasts undergo aerobic respiration and reproduce in large quantities. C Lu H I II O Lu + Lu O II → Lu CO II + Lu H II O 5. Under anaerobic conditions, yeast can carry out alcoholic fermentation. C Lu H a two O Lu → two C two H5OH + two CO two Lu, about 0 ℃ is the most suitable for yeast reproduction Alcoholic fermentation is generally controlled in the temperature of a bar ℃ - 2 5 ℃ Ch, in the process of natural fermentation of wine, play a major role in the attachment of the surface of the skin of the grapes of the wild-type yeasts. During fermentation, as the alcohol concentration increases, the pigments from the red grape skins enter the fermentation broth, giving the wine a deep red color. Yeasts can grow and multiply in an oxygen-poor, acidic fermentation broth, whereas most other microorganisms are constrained by their inability to adapt to this environment. Bar, Acetobacter is a unicellular bacterium (prokaryote), the metabolic type is heterotrophic aerobic, and the mode of reproduction is dichotomous. 9. When there are sufficient sources of oxygen and sugar, Acetobacter breaks down the sugar in the grape juice into acetic acid; when there is a lack of a sugar source, Acetobacter changes the ethanol to acetaldehyde, and then changes the acetaldehyde to acetic acid. Two C two H5OH + four O two → CH three COOH + land H two O one 0, the role of the control of fermentation conditions ① acetic acid bacteria are particularly sensitive to the content of oxygen, when the deep fermentation, even if only a short period of time interruption of the passage of oxygen, but also cause the death of acetic acid bacteria. ② acetic acid bacteria optimal growth temperature of three 0 to three 5 ℃, control the fermentation temperature, so that the fermentation time is shortened, but also to reduce the opportunity for contamination of stray bacteria. ③ there are two ways to generate acetic acid: direct oxidation and oxidation with alcohol as the substrate. A one, the experimental process: selection of grapes → rinse → juice → alcoholic fermentation → fruit wine ( → acetic acid fermentation → fruit vinegar) A two, alcohol test: fruit juice fermentation whether there is alcohol production, you can use potassium dichromate to test. Under acidic conditions, potassium dichromate reacts with alcohol to show a gray-green color. First, add two mL of fermentation solution in a test tube, and then drop into the concentration of material for three mol / L of H two SO four three drops, shaking and mixing, and finally add three drops of saturated potassium dichromate solution at room temperature, oscillating the test tube, observe the color a three, the inflatable port is connected to the inflatable pump for inflation during acetic acid fermentation; exhaust port is used to discharge carbon dioxide in the alcoholic fermentation; the outlet port is used for sampling. The exhaust port is connected to the bottle through a long, curved hose, the purpose of which is to prevent contamination by airborne microorganisms. The purpose of the opening downward is to facilitate the discharge of carbon dioxide. When the device is used to make wine, the filling port should be closed; when vinegar is made, the filling port should be connected to an air pump to feed oxygen. (a) Do you think the grapes should be rinsed or the stems removed first? Why? The grapes should be rinsed first, and then the stems should be removed, in order to avoid the breakage of grapes caused by the removal of stems, which will increase the chance of contamination by bacteria. (ii) In what ways do you think the fermentation broth should be prevented from being contaminated? For example, the grapes should be rinsed before removing the stems; the press and fermentation device should be cleaned and sterilized with alcohol; each time when venting, only loosen the cap of the bottle, do not open the cap completely, and so on. (iii) When making wine, why should the temperature be controlled at 1 bar ~ 2.5°C? When making grape vinegar, why should the temperature be controlled at 30～35℃? Temperature is an important condition for the growth and fermentation of yeast. Around 20℃ is the most suitable for yeast to multiply. Therefore, it is necessary to control the temperature within its optimal temperature range. Acetobacter is a thermophilic bacterium, and its optimum growth temperature is 3-0 to 3-5°C. Therefore, the temperature should be controlled at 3-0 to 3-5°C. Subject two the production of curd a variety of microorganisms involved in the fermentation of tofu, such as Penicillium, yeast, Aspergillus, Trichoderma, etc., which plays a major role in the Trichoderma. Trichoderma is a filamentous fungus. The metabolic type is heterotrophic aerobic. Reproduction is sporulation. Camp putrefactive life. Second, the principle: Trichoderma and other microorganisms produce protease can be broken down into small molecules of protein in the tofu peptides and amino acids; lipase can be hydrolyzed fat into glycerol and fatty acids. Third, the experimental process: let the tofu on the growth of trichoderma → salt curing → plus brine soup bottling → sealed curing four, brewing curd the main production process is the tofu pre-fermentation and post-fermentation. The main role of pre-fermentation: I. Create conditions for the growth of mold. Two. Make the hair enzyme to form a bacterial film wrapped around the tofu so that the curd molding. Post-fermentation is a process in which enzymes and microorganisms are involved in biochemical reactions. The aroma of curd is generated through the mitigating effect of various auxiliary materials and enzymes. 5, the tofu cut into lacquer 5px x lacquer 5px x two 5px a number of pieces. The moisture content of the tofu used is about 0% of the paint, too much water is not easy to form curd. * Moisture determination method is as follows: accurately weighed by the mortar and pestle grinding into a paste of the sample 5 ~ 0g (accurate to 0.0 two mg), placed in a known weight of the evaporation dish, evenly spread, in a 00 ~ 05 ℃ electric drying oven in four h, remove the desiccator placed in the dryer cooled to room temperature after weighing, and then baked three 0min, until the weight claimed to be unchanged. The formula for calculating the moisture content (%) of the samples is as follows: (mass of container and sample before drying - mass of container and sample after drying)/mass of sample before drying - Growth of Trichoderma reesei: Conditions: the block of tofu was placed flat in a cage drawer, and the cage drawer in the control of one 5 ~ one bar ℃, and maintain a certain temperature. Sources: i. From airborne Trichoderma spores, ii. Direct inoculation of good trichoderma species Time: 5 days - Salt pickling: the growth of trichoderma blocks of tofu in layers neatly arranged in the bottle, while adding salt layer by layer, with the number of layers and increase the amount of salt, close to the mouth of the bottle surface of the salt should be laid thicker. Salt and marinate for about bar days. -When salting with salt, pay attention to the control of the amount of salt: too low a concentration of salt is not enough to inhibit the growth of microorganisms, which may lead to tofu corruption and spoilage; too high a concentration of salt affects the taste of curd -The role of salt: I. Inhibit the growth of microorganisms to avoid spoilage. ii. Separate out water, so that the bean curd becomes hard and not easy to be crispy in the post-production process. iii. Seasoning to give curd the necessary salty flavor iv. Leach the protease from the hair enzyme mycelium. -Preparation of brine soup: brine soup is directly related to the color, aroma and taste of curd. Brine broth is prepared from wine and various spices. The content of wine in the broth is generally controlled at about one or two percent. -The role of wine: I. Prevent contamination of fungi to prevent preservation of two. Combine with organic acid to form ester, give curd flavor. iii. Alcohol content and late fermentation of curd has a great relationship with the length of time, the higher the alcohol content, the greater the inhibition of protease, so that the maturation period of curd is extended; alcohol content is too low, the protease activity is high, accelerate the hydrolysis of proteins, the rapid reproduction of stray bacteria, tofu is easy to rot, difficult to form blocks. -Role of spices: i. Flavoring role two. Bactericidal and antiseptic effect III. Participate in and promote the fermentation process - to prevent contamination of stray bacteria: ① used to pickle fermented bean curd glass bottles, scrubbed clean and sterilized with boiling water. ②When bottling, operate quickly and carefully. After neatly arranging the tofu and adding the marinade, seal the bottles with adhesive strips. When sealing the bottle, it is best to pass the mouth of the bottle through the flame of the alcohol lamp to prevent contamination of the mouth of the bottle. QUESTIONS AND ANSWERS (a) Using your knowledge of biology, explain what happens when tofu grows white hairs? The white hairs growing on tofu are the white mycelium of Trichoderma. Strictly speaking, it is an erect mycelium and there are creeping mycelium in tofu. (ii) Why is it necessary to sprinkle a lot of salt to pickle tofu with long hairs? Salt prevents contamination by stray bacteria and prevents the tofu from spoiling. (c) Which kind of tofu we usually eat is suitable for making curd? Tofu with a water content of about 0% is suitable for making curd. Tofu with high water content is not easy to form. (d) When you eat curd, you will notice that there is a dense "skin" on the outside of the curd. How is this "skin" formed? Is it harmful to the human body? What is its function? The "skin" is the mycelium (creeping mycelium) that grows on the surface of the curd during the pre-fermentation period, which is harmless to humans. It forms the "body" of the curd and gives shape to the curd. The microorganisms used in making kimchi are lactic acid bacteria, whose metabolism is heterotrophic and anaerobic. Under anaerobic conditions, glucose is broken down into lactic acid. The mode of division is bifurcation. The reaction formula is: C Lu H 1 2 O Lu 2 C 3 H Lu O 3 + energy Antibiotic-containing milk does not produce yogurt because antibiotics kill the lactic acid bacteria. Common lactic acid bacteria are Streptococcus lactis and Lactobacillus lactis. Lactobacillus is commonly used to produce yogurt. -Nitrites are white powders that are soluble in water and are used as food additives in food production. -Dietary nitrite is generally not hazardous to human health, the national regulations in meat products not more than 30mg/kg, pickles not more than 20mg/kg, infant milk powder not more than 2mg/kg. Nitrite is absorbed with the urinary excretion of the body, but in the appropriate pH, temperature and certain microbial effect of the formation of carcinogenic substances nitrosamines. -Generally in the pickling 0 days after the nitrite content began to decrease, so in 0 days after the consumption of the best * Determination of the nitrite content of the principle of hydrochloric acid acid, nitrite and p-aminobenzene sulfonic acid diazotization reaction, and N - a - naphthalene ethylenediamine hydrochloride combined with the formation of a rose-red dye, and the concentration of the known standard coloring solution visually comparable to the estimated content of nitrites in the kimchi