Materials and Methods Yeast, Acetobacter, fresh persimmon, sucrose, salt, citric acid and sulfur dioxide. There are many ways to remove the astringency of persimmon fruit, including alcohol, cold water and limewater.
By analogy, the simpler method is to remove astringency with warm water. Inoculate the activated dry yeast into persimmon juice with appropriate sugar content, and conduct submerged fermentation at 28℃ until the alcohol content no longer rises, and then transfer to acetic acid fermentation. Bian Xiao recently
I visited Taobao and bought several bottles of puree persimmon vinegar at @ 8 Miracle. The effect is very good.
Inoculate the expanded acetic acid strain into the alcohol fermentation broth, and carry out acetic acid fermentation at a certain temperature, periodically oscillating, with the acetic acid content no longer rising as the fermentation end point.
2.
The technological process is as follows: persimmon fruit → selection → cleaning → peeling → coring → astringency removal → dicing → juicing → persimmon juice → sterilization → alcohol fermentation → acetic acid fermentation → sterilization → aging → pouring vinegar → filtration → detection → production.
Products. Dry yeast → activation and expansion → adding acetic acid bacteria in alcohol fermentation → expanding culture → adding fermentation link 3. Operation points (3) remove astringency and peel off the skin.
Put the pitted persimmon fruit into a vat, accounting for about 70% of the container, then pour warm water at 40℃ ~ 50℃ into the vat, and cover the lid of the vat tightly with an old quilt or other thermal insulation materials. Due to the lack of oxygen in water and the high temperature, the fruit
Lack of oxygen and severe breathing make persimmon get rid of astringency in about 24 hours. (4) sterilizing and cooling. The squeezed persimmon juice is heated to 80℃ 10 ~ 20min, and then cooled to normal temperature. Persimmon fruit
The acid content is low, so it is necessary to add enough sulfur dioxide to prevent the infection of miscellaneous bacteria. (5) Adjust the sugar content of persimmon juice to 20% with sucrose and adjust the acidity to 0.5% with citric acid.
Active dry yeast can be added to alcohol fermentation. Dry yeast should be activated before use. Weigh the required amount of active dry yeast, add it to 100ml of 8% sucrose solution, and survive at 30℃.
It will take 30 minutes. The activated yeast was added to persimmon juice according to the inoculation amount of 0.5%, the fermentation temperature was controlled at 28℃, and the fermentation parameters (alcohol content and sugar content of mash) should be checked regularly during the fermentation.
Measure. (6) Acetic acid fermentation: Inoculate a certain amount of expanded acetic acid strains, conduct acetic acid fermentation in mature wine mash at 28℃ ~ 40℃, and detect vinegar in the fermentation process at any time.
Changes in acid and alcohol concentrations. (7) After the fermentation of the aged vinegar is finished, the aged vinegar is filtered by a pump, then the salt with the mass fraction of 1% ~ 2% is added, and then it is heated to 80℃ by a tube heat exchanger for rapid cooling.
Bacteria can age people in semi-finished cans. 4. Precautions (1) Study on the method of removing astringency. Persimmon fruit contains a lot of tannins, which makes persimmon astringent. Tannins are divided into two categories, one is
Class is soluble tannin, which is a monomer or oligomer of tannin. This tannin condenses with protein of tongue mucosa, which makes people have astringent taste. The second is insoluble tannin, which is a high polymer of tannin, and this tannin does not coagulate with protein of tongue mucosa.
Solid, not astringent. Therefore, in the processing of persimmon vinegar, the astringency should be removed first. (2) Determination of alcohol fermentation cycle Under anaerobic conditions, alcohol fermentation was carried out by using yeast through EMP route.
The process of fermenting glucose into ethanol and carbon dioxide. The changes of sugar content and alcohol content at different times were recorded. In the process of alcohol fermentation, with the extension of fermentation time, the sugar content decreased and the alcohol content increased. exist
On the sixth day of alcohol fermentation, the alcohol volume fraction reached 4.9% and the sugar content was 2.0%, and the alcohol content and sugar content did not change obviously with time. Therefore, the fermentation period is determined to be 6 days. (3)
Study on Fermentation Conditions of Acetic Acid Ethanol is oxidized to acetic acid by Acetobacter, which is called acetic acid fermentation and is the main link in vinegar production. Fermentation temperature is an important factor affecting acetic acid fermentation, and too high temperature will lead to fermentation.
The bacteria aging is too fast; Too low temperature is not conducive to the growth of acetic acid bacteria, resulting in low acid production. Through the determination of acetic acid production at different temperatures, it can be known that the highest acid production is at 35℃. Inoculum concentration
It is also an important factor affecting acetic acid fermentation. The inoculation amount is too large, the fermentation speed is fast, and most nutrients are consumed in the growth and reproduction of bacterial cells, but the vinegar production is reduced. The inoculation amount is too low, the fermentation speed is slow, and the fermentation broth does not ferment.
Sufficient low acid yield. Therefore, the optimal inoculation amount is 10%. In the process of acetic acid fermentation, the content of alcohol decreased continuously, while the acidity increased continuously, indicating that acetic acid bacteria oxidized alcohol into acetic acid. acetic fermentation
After 12 days, the concentration of acetic acid basically stopped rising and the alcohol content reached the lowest. At this time, the acidity reached 5.0% and the alcohol content was 0. 13%, which was the end point of acetic acid fermentation. (4) Exceeding the product index
It is reddish-brown, with appropriate concentration, clear and transparent, free of mold floating film and sediment, with persimmon vinegar's unique aroma, rich ester fragrance, soft sour taste, outstanding persimmon flavor and no peculiar smell; Total acid (calculated by citric acid) 4.6%, alcohol
The content is 0. 1 1%, and the sugar content (calculated by glucose) is1.3%; The total number of bacteria is not higher than 5000 CFU/ml, and the coliform group is not higher than 3MPN/ 100ml. No pathogenic bacteria can be detected.