When wine is bottled, it must be carefully considered whether the wine has reached the goal of sterilization and sterilization. In order to achieve this precisely, bottled wines must be tested quickly and reliably. Here are listed three inspection methods, only for the friends in the actual production, according to the actual conditions of the company for reference.
One, Geisenheimer test
The wine to be tested under sterile conditions, with its equal amount of grape juice, provides a good breeding condition for the yeast, and the yeast begins rapid propagation and fermentation. The rate of yeast reproduction and the intensity of fermentation are measures of the degree of contamination of the tested sample.
The specific operation is as follows:
Take 3 standard test tubes, inject 10 mL of grape juice, seal with tampon and place in an autoclave for sterilization; wrap the straws in paper and sterilize them at 160°C. Then carefully remove the cork from the wine bottle, immediately use the flame to remove the microorganisms attached to the bottle mouth, and then use a sterile pipette to suck out the 10 mL of the tested wine from the bottom of the bottle and move it into the test tube of the sterilized grape juice. Three parallel samples.
If the sample to be tested has more live yeast, the degree of fermentation can be verified within 3-5 days; if there is less yeast, the fermentation needs twice the time, which can determine whether the production line is in a controlled state and determines the bottled wine. Does the product have a quality accident such as turbidity after leaving the factory?
This method is very simple, does not require special equipment, is very suitable for small wineries, which is its advantages. The disadvantage is that only the presence of yeast in the wine can be determined and the quantitative analysis cannot be performed.
Second, the membrane filtration method
Filter the test wine with different pore sizes (typically 2 microns or less in pore size), filter the test wine under aseptic conditions, isolate the yeast and other microorganisms, and then grow and cultivate the microorganisms on the filter, calculate the number of colonies that appear, and Perform other necessary checks.
The method of operation is as follows:
Thoroughly sterilize all the instruments and vessels involved in the filtration process (article: China Wine News, China Wine News Network) and filter it under aseptic conditions. Prior to each analysis, the filters and filters were sterilized in an autoclave, and the sterilized filters were placed in the filters using flame-fired tweezers.
Before the bottle is opened, you must carefully wipe the bottle with 75% alcohol, carefully remove the cork, and do not allow the bottle opener to pass through the cork.
At the beginning, pull out the cork stopper by three-fourths. Then gently remove the cork stopper by hand. Burn the bottle before using the flame and pour the wine into the filter funnel little by little.
After the filtration is completed, remove the filter pieces from the scorpion fired in the funnel, place them in a petri dish, place them flat, pour the appropriate amount of yeast medium (about 3 mL), and then mark the date and sample number, and place In a biological incubator, culture at 25°C for 3-5 days. In order to avoid condensed water from affecting colony growth, the culture dish was snapped in the incubator. If the yeast on the filter is alive, the yeast will reproduce and colonies will appear on the medium.
If no colony growth is detected, it indicates that the wine being tested is stable and no clouding caused by yeast occurs; if there are more than 5 colonies per bottle, it indicates that the wine is not completely sterilized or sterilized, and the wine is not Stability factors should be strictly examined in every aspect of the production process until the cause is identified.
This method can quantify various microorganisms in bottled wine, but it is necessary to select appropriate pore size filters and culture media, and operate by skilled personnel who have mastered basic microbiology.
Third, rapid test method
Membrane filtration can use microscopic examination of the filter to quickly detect live yeast; rapid assays can distinguish between dead and living microbes, but require bottled wine to be free of other suspended materials.
At a suitable temperature, within 8 to 14 hours, cells with reproductive ability grow into tiny colonies. Observations with a microscope can distinguish between dead and non-reproductive colonies. Viable cells form small colonies when they are cultured, and dead organisms only exist individually.