I. teaching material analysis

Elective course 1 is an elective course with students as the main body, and scientific inquiry is learned through experimental design and operation practice. This module focuses on cultivating students' scientific inquiry ability, such as designing experiments, hands-on operation, collecting evidence, etc., and the production of fruit wine and vinegar is closely related to daily life, which students have a deep understanding of. The purpose of this study is to let students carry out traditional fermentation under experimental conditions.

Second, the teaching objectives

1, knowledge target:

Understand the production principle of fruit wine and fruit vinegar.

2, ability goal:

① Students design the process of making fruit wine according to the principle of making fruit wine and experience the actual operation of making fruit wine.

② In the process of analyzing and evaluating fruit wine production results, cultivate students' experimental analysis ability and rigorous thinking ability.

3, emotional goals:

By tracing the history of fruit wine brewing, we can cultivate students' national pride and infiltrate STS education.

Third, the teaching focus:

① Explain the production principle of fruit wine and fruit vinegar.

(2) Design and manufacture equipment for fruit wine and fruit vinegar.

Four, teaching difficulties:

Control of fermentation conditions in production process

Teaching process of verbs (abbreviation of verb)

Introduction:

In the long history of the Chinese nation, many things are in the forefront of the world, and so is wine, which has its own glorious chapter. There are many interesting legends about wine in the records. Apes say that the main food of apes is sugary fruits. When the fruit is ripe, apes store a lot of fruit in the "stone depression". After a period of time, liquid with special fragrance will flow out. This is the earliest fruit wine.

In the domestic market, more and more fruit wines have appeared in recent years, such as chinese wolfberry wine and plum wine.

Fruit wine and life-Although fruit wine contains alcohol, compared with liquor, beer and wine, its content is very low, generally between 5- 10, and the highest is only 14. Therefore, it is drunk by many adults as a soft drink after meals or before going to bed.

Fruit wine is simply a wine made by absorbing all the nutrients in fruit, which is rich in vitamins and amino acids needed by human body. Sometimes nutrients that can't be absorbed even if you eat fruit raw can be absorbed through fruit wine, because nutrients have been completely dissolved in fruit wine. Fruit wine contains a lot of polyphenols, which can inhibit the accumulation of fat in human body and make it difficult for people to accumulate fat and fat. In addition, compared with other wines, fruit wine has a more obvious effect on caring for the heart and regulating women's emotions.

The project 1 introduces the production technology of fruit wine and fruit vinegar from the background of the project, and then introduces the experimental principle, the schematic diagram of the experimental process and the information provided.

First, the basic knowledge

1. principle of fruit wine brewing

Read the textbook and complete the following questions:

(1) What microorganisms are needed to make fruit wine?

(2) Morphology, structure, distribution, species and colony of yeast?

(3) What are the metabolic types of yeast and the reaction formula of its respiratory process?

(4) What is the optimum temperature for yeast?

(5) Why is wine generally red?

(6) What is fermentation? Is fermentation equivalent to anaerobic respiration? What are the practical applications of yeast?

(1) Morphology, structure, distribution, species and colony of yeast

(1) shape and structure

Yeast is a unicellular fungus, belonging to eukaryotes. The cell size is 1~30um, round and oval.

Thinking: What structures do you think are in yeast cells?

What do you think is the difference between bacteria and yeast in cell structure?

② Reproduction

There are budding propagation, fission propagation and spore propagation in yeast, but most of them reproduce asexually through budding. When the temperature is low, spores form and enter a dormant state, and when the temperature is suitable, they germinate and reproduce, and the reproduction speed is fast.

③ Colony:

Discussion: Do you know what a colony is? What does a group belong to in ecology?

Colonies formed by yeast on solid medium have wet, sticky and white or pink surfaces. (In liquid culture medium, some bacteria form a thin film on the surface of the liquid, or yeast rings appear on the wall of the container, or precipitation occurs. )

④ Living environment

In nature, yeasts are widely distributed, but most of them are distributed in acidic environments with high sugar content, such as fruits, flowers and bark. (Some can be worms, others can be pathogenic, such as thrush and pulmonary infection caused by Candida albicans. Common yeasts in food include beer yeast, grape juice yeast, Roux yeast (brewed with soy sauce), coccidia, Pichia farinosa and so on. ) Throughout the year, the soil is always the base camp of yeast.

Thinking: When fermenting wine, should the grapes be disinfected? Why?

What do other microorganisms have to do with yeast?

(2) Metabolic types of yeast and its respiratory process.

① Breathing of yeast

The production of fruit wine is inseparable from yeast. Yeast is a facultative anaerobic microorganism,

Under aerobic conditions, the reaction formula is as follows: enzyme

C6h1206+6o2co2+6h20+energy

Under anaerobic conditions, the reaction formula is as follows: enzyme

Energy of C6H 12O6 2C2H5OH+2C02+

Thinking:

In the process of fermentation, what should be done if yeast is to multiply in large quantities?

What if you want to drink? Why?

③ Fermentation

1). The concept of fermentation

Broadly speaking, it is the process of mass production of various metabolites through the cultivation of microorganisms. Including aerobic fermentation (such as acetic acid fermentation, glutamic acid fermentation) and anaerobic fermentation (such as alcohol fermentation).

Narrow sense: refers to the anaerobic respiration of microorganisms (including alcohol fermentation, lactic acid fermentation, etc. ).

2). So: fermentation ≠ anaerobic respiration.

3). Application:

Brewing, making steamed bread, making bread, brewing wine, producing medicinal yeast tablets, producing vitamins, producing antibiotics, etc.

(4) Temperature requirements

The optimum temperature for reproduction: 20℃;

The optimum temperature for alcohol fermentation is 65438 08 ~ 25℃.

Thinking: Do you know why yeast needs proper temperature?

What does it mean that yeast has different optimum temperatures?

Supplement: Effect of temperature on fermentation

Yeast can only survive at a certain temperature. When the temperature is lower than 10℃, the yeast develops slowly. With the increase of temperature, the propagation speed is accelerated, and 20℃ is the best propagation temperature, at which time the yeast has fast propagation speed and strong vitality. When the temperature exceeds 35℃, the growth of yeast is inhibited and the propagation speed drops rapidly. At 40℃, yeast stopped budding and began to die. In order to obtain the fermentation broth with high alcohol concentration and reduce the actual loss, the fermentation temperature must be controlled.

Do you know that?/You know what? Do you know that?/You know what?

1, generally speaking, the reason why wine is red?

In the fermentation process, with the increase of alcohol content, the pigment in red grape skin also enters the fermentation broth, making the wine red. )

2. What is the basis for dividing wine into dry red and dry white?

(1, divided into white wine, red wine and pink wine according to the color of wine.

White wine: brewed with white grapes, separated from the skin and fermented;

Red wine: brewed with red grapes and fermented with mixed grape skins and juice;

Pink wine: the color is between white wine and red wine, and the skin fermentation time is short.

2. According to the sugar content of wine, it can be divided into four types: dry type, semi-dry type, semi-sweet type and sweet type.

Dry wine: sugar content is less than 4g/L;

Semi-dry wine: the sugar content is between 4g- 12g/L;

Semi-sweet wine: sugar content is between 12g-50g/L;

Sweet wine: sugar content is higher than 50g/L ..)

(5) strain source:

(In order to improve the quality of fruit wine in industrial production, artificially cultured yeast, such as dry yeast or medicated wine, can also be directly added to fruit juice. )

2, the principle of fruit vinegar production

Read the textbook and think about the following questions:

(1) What is the morphology of Acetobacter? Cell structure?

(2) What are the practical applications of Acetobacter?

(3) What are the metabolic types of Acetobacter?

(4) How to make fruit vinegar?

Morphology of Acetobacter (1)

1). From ellipse to rod, there are single, right and chain. It moves or does not move with the flagella and does not form spores. It belongs to prokaryote, divides and reproduces, and its metabolic type is heterotrophic aerobic. Compared with yeast, Acetobacter has the most important characteristics. )

2). Application: vinegar and fruit vinegar.

(2) The principle of making fruit vinegar,

Acetobacter is an aerobic bacterium. Only when there is enough oxygen can it carry out vigorous physiological activities. The biofilm observed on the surface of sour wine is formed by the propagation of acetic acid bacteria on the liquid surface. Experiments show that Acetobacter is particularly sensitive to oxygen content equivalent. Acetobacter will die even if oxygen supply is interrupted for a short time during submerged fermentation. When the oxygen source and sugar source are sufficient, acetic acid bacteria decompose fructose in grape juice into acetic acid;

enzyme

C6H 12O6 →3CH3COOH (acetic acid)

When there is no sugar source, acetic acid bacteria turn ethanol into acetaldehyde, and then acetaldehyde into acetic acid (the reaction formula is as follows). The optimum growth temperature of Acetobacter is 30℃-35℃.

enzyme

enzyme

2C2H5OH+O2 →2CH3CHO (acetaldehyde) +2H2O 2CH3CHO+O2 →2CH3COOH (acetic acid)

Transition: According to this principle, how do we design the production scheme of fruit wine and fruit vinegar?

Tip: Consider from the following three aspects: material selection, experimental device design and operation flow.

Second, the experimental design

1. Schematic diagram of the experimental process of fruit wine and fruit vinegar

blush

Juice

alcoholic fermentation

acetic fermentation

Fruit wine

fruit vinegar

Grapes

Read the textbook on 3-4 pages and discuss the experimental devices of students A and B:

Answer: unscrew the bottle cap every time you exhaust, and don't completely uncover the bottle cap; When making vinegar, open the bottle cap, cover it with a layer of gauze, and carry out grape vinegar fermentation. (To prevent the fermentation broth from being polluted, because every step of operation may be mixed with miscellaneous bacteria)

The functions of vent, exhaust port and discharge port in fruit wine and fruit vinegar fermentation device were analyzed. Why is the vent connected to the bottle through a long and curved hose?

The inflating port is connected with an inflating pump for inflating during acetic acid fermentation; The exhaust port is used to exhaust carbon dioxide in the process of alcohol fermentation; The discharge port is used for sampling. The exhaust port should be connected to the bottle body through a long and curved hose, and its purpose is to prevent microbial pollution in the air. When using this device to make wine, the vent should be closed; When making vinegar, the air inlet should be connected with an air pump and input oxygen.

2. Experimental operation

(1) Selection and treatment of materials

Choose fresh grapes, wash the grapes and remove the branches before juicing.

① Take 500g grapes and remove the branches and rotten leaves.

② Wash the grapes with clean water 1-2 times to remove dirt. (Be careful not to rinse too many times. Why? )

Discussion: Do you think we should wash the grapes or go to the branches first? Why?

(It should be washed first, and then pruned, so as to avoid damaging the grapes and increase the chance of being polluted by miscellaneous bacteria. )

(2) disinfection

Discussion: What do you think should be done to prevent the fermentation broth from being polluted?

It needs to be considered comprehensively from the fermentation process, because every step of operation may be mixed with miscellaneous bacteria. For example, juicers and fermentation devices should be cleaned; Just unscrew the bottle cap and don't completely uncover the bottle cap every time you exhaust. )

① The juicer should be cleaned and dried.

② The fermentation device should be cleaned and disinfected with 70% alcohol.

(3) juicing

Put the washed branchless grapes into a juicer for juicing.

④ Fermentation

① Put the grape juice into the fermentation bottle, leaving about 1/3 space.

(as shown on the right), and close the air inlet.

② During brewing, the temperature should be strictly controlled at 18℃ ~ 25℃ and the time should be controlled at 10 ~ 12d. Fermentation can be carried out through the discharge port. Monitor in time.

(3) During the production of grape vinegar, the temperature should be strictly controlled at 30℃ ~ 35℃ for the first 7 ~ 8 days, and pay attention to the timely inflation through the inflation port.

Third, the result analysis and evaluation

1. Due to fermentation, most of the sugar in grape pulp is converted into CO2 and C2H5OH, and there are a few fermentation by-products. The emission of CO2 is more and more vigorous, which makes the fermentation broth boil and CO2 is discharged from the exhaust port. After 10 days of fermentation, this phenomenon is most obvious. The heat generated in the fermentation process will increase the temperature of the fermentation broth, but the temperature of alcohol fermentation should be strictly controlled at 18℃ ~ 25℃. In the fermentation process, the pigment and other components on the peel will gradually dissolve in the fermentation broth. On the surface of the fermentation tank, the cover of the floating tank is formed.

2. The control group was set up, and the grape juice was autoclaved and put into two fermentation bottles, A and B, respectively, with a space of 1/3 in each bottle. Adding yeast to group A but not to group B for fermentation proved that the production of wine was due to the action of yeast. It is proved that acetic acid is produced in grape vinegar, and the simple and easy method is to taste or identify it with pH test paper.

3. The produced wine is bright in color, refreshing and soft, and fruity; Fruit vinegar is amber or brownish red, with unique fruit fragrance, soft acidity, slightly sweet and no astringency.

Fourth, the extension of the subject.

Whether the fruit juice produces alcohol after fermentation can be tested by potassium dichromate. Under acidic conditions, the reaction of potassium dichromate with alcohol is grayish green. During detection, 2mL of fermentation broth was first added to the test tube, and then 43 drops of H2SO43 with a molar concentration of 3mol/L were dripped and shaken evenly. Finally, drop 3 drops of saturated potassium dichromate solution at room temperature and shake the test tube to observe the color change. Think about it, if you want to make the test results more convincing, how should you design the comparison?

Verb (abbreviation for verb) related links

1. In order to improve the quality of fruit wine and better inhibit the growth of other microorganisms, artificially cultured yeast can be directly added to fruit juice. In order to cultivate yeast artificially, it is first necessary to obtain pure yeast strains. How to isolate yeast attached to grapes and obtain pure strains? You can refer to "Topic 2: Cultivation and Application of Microorganisms" for further information and try again.

2. When making fruit vinegar, you can also directly add acetic acid bacteria to fruit wine. Acetobacter strains can be purchased from local vinegar factories or strain preservation centers. You can also try to separate acetic acid bacteria from vinegar. See topic 2 for the separation method.

Related knowledge:

Fruit wine is made by anaerobic fermentation of yeast, and fruit vinegar is made by aerobic fermentation of acetic acid bacteria. Yeast and Acetobacter are both microorganisms, so what are microorganisms and which organisms belong to microorganisms?

1, the concept of microorganism

A general term for organisms with small size and simple structure can usually be seen clearly by optical microscope and electron microscope.

2. Microorganism

There are about 6.5438+million kinds of microorganisms;

Microorganisms are the richest biodiversity resources on earth. Microorganisms are the second largest group in the life world after insects. However, due to the microscopic nature of microorganisms and the limitation of research methods, many microbial populations cannot be isolated and cultured, and the proportion of known species to estimated species is still very small.

practise

2. Tip: mass production needs to be considered more comprehensively and thoroughly, such as the source and selection of raw materials, the cultivation and selection of strains, the automatic control of fermentation equipment and fermentation conditions, and how to strictly control the pollution of miscellaneous bacteria; Wait a minute. In addition, whether it is wine or grape vinegar, the fermentation broth detected in the experiment is not a product in the sense of commodity. In actual production, it is necessary to precipitate, filter, sterilize and bottle to get the finished wine or vinegar. Wine also needs to be fermented under certain facilities and conditions (such as oak barrels and wine cellars) to obtain specific flavor and color.

3. Prompt: Problems such as plant, equipment investment, raw material procurement, number and salary of workers, product types, production cycle, sales channels and profits need to be considered.