2. Process flow
Jujube → washing → beating → enzyme treatment (pectinase) → sterilization → filtration → alcohol fermentation → acetic acid fermentation (acetic acid bacteria) → filtration → blending → sterilization → finished products
3 operating points
(1) Preparation of jujube pulp. Pick fresh wild jujube washed with water, and beaten into a pulper to separate (mesh 0.6 ml, the water used should be demineralized). Separate the jujube pulp into the enzymolysis tank and add 0.01% sodium sulfite. Sodium sulfite is added for the purpose of suppressing harmful microorganisms, in particular, inhibiting the growth of wild yeast that are not favorable for fermentation.
(2) Yeast culture. A high-quality yellow wine yeast was selected and a working starter was obtained through four-stage expansion culture. Specific steps are as follows: Yeast bacteria → 250 ml flask → 24 hours of cultivation → 1000 ml flask → 18-20 hours of culture → 15 liters of Carlsberg → 19 hours of cultivation → 50 liters of seed tank → 8-20 hours of cultivation → work Fermentation agent.
Among them, the first two grades of culture generally use wort as the culture medium, and the latter two grades can use the raw juice of the wild jujube after the enzymolysis as the culture medium. At the same time, the pH is adjusted to about 4.2 and the temperature is 27-28 oC. 1:10. During the entire yeast culture, bacterial contamination should be strictly prevented.
(3) Alcohol fermentation. Adding 20% ​​of the working starter to the enzymatically treated sour jujube juice requires that the jujube juice can not be loaded in excess of 2/3, the fermentation temperature is controlled at 26-33oC, and the fermentation time is 2-3 days. At this time, the alcoholic fermentation is basically End, then use alcohol to adjust the alcohol content to about 8%.
(4) Acetic acid fermentation. The above-mentioned jujube fermentation broth is added to the fermentation tower at one time, and 10% of the acetic acid bacteria working fermentation agent is added at the same time, and then the fermentation is carried out according to the principle of "fixed back pouring" and "combined with warm pouring", about 90 minutes each. The vinegar is poured back with a pump and the product temperature is controlled between 35-42oC. The ventilation rate is controlled at 1:0.3 (volume ratio). If the product temperature is too high or too low, it should be flexible to adjust the frequency of reflow and air flow, about 2-3 days after the reflow, acetic acid fermentation process is basically completed, the determination of acidity is no longer when it is the end of acetic acid fermentation.
The use of a fermentation tower for acetic acid fermentation can greatly shorten the fermentation cycle and the production cycle is only about 8 days. The main reason is that the surface of the packing material in the tower is fully in contact with oxygen, resulting in substantially complete oxidation of ethanol to acetic acid.
(5) Sterilization. The fermented fruit vinegar was filtered through a plate and frame filter, and then the acidity was adjusted to 5%, and then blended as needed. Then it is sterilized by the plate heat exchanger, and it is required to be kept at 95oC for 5 minutes, and the final filling is finished product.
4. Quality indicators
(1) Sensory indicators. The color is dark brown, sour and soft, slightly sweet with acid, and a touch of jujube.
(2) physical and chemical indicators. Acidity ≥ 5%, soluble solids content ≥ 8%.
(3) Health indicators. The total number of bacteria is ≤100 cells/g, E. coli ≤3 cells/g, and pathogenic bacteria cannot be detected.
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