China is a big beer producing country, and the annual production of yeast mud is about 600,000 tons, of which a small amount of beer remains.
At present, yeast sludge is mainly used as feed, and the residual beer is not effectively utilized, resulting in waste of resources. In theory, we can use the waste beer in the yeast mud as raw material, and ferment it into beer flavored vinegar by acetic acid bacteria.
According to some data, beer flavored vinegar is richer in nutrition than traditional food vinegar, which not only increases the added value of beer products, but also reduces environmental pollution.
First, the process
After the waste yeast sludge is centrifuged, the supernatant is boiled, and the precipitate is allowed to stand and then fermented with acetic acid bacteria. After filtration and clarification, the beer flavored vinegar is obtained.
Second, the process is difficult
Because the yeast mud is prone to autolysis during transportation and pressure filtration, the macromolecular substances in the yeast, such as proteins and polyphenols, are difficult to be filtered or filtered, and then easily returned to the vinegar of beer flavored vinegar. Dim, turbid, and even precipitation, which is the most challenging problem in the process.
Enterprises in the actual operation can choose different clarifying agents, such as bentonite, brewing tannins and PVP Chinese wine industry weather vane Huaxia wine newspaper postal code 23-189 local post office can subscribe to P and other processing beer flavored vinegar after fermentation, according to The experimental results ultimately determine which clarifying agent to use.
Bentonite forms a stable suspension in water, and the fine particles are negatively charged. Most of the turbidity in beer flavored vinegar is positively charged. Therefore, the turbid substance easily reacts with the bentonite to produce a flocculent precipitate.
The tannin can form a tannic acid salt complex with the protein, and the suspended matter in the wound solution sinks. In addition, tannins also carry a negative charge, which can be coagulated and precipitated with a positively charged macromolecular substance.
PVPP has the characteristics of physiological safety, water absorption, water insolubility and complexation, and can adsorb polyphenols. The clarification effect of different clarifying agents can be measured by measuring the light transmittance.
After the clarifying agent is determined, the factor level table can be designed together with the boiling pressure, the boiling time, etc., and the optimum process parameters are searched by the orthogonal method.
Third, the experimental method
In the experiment, the total nitrogen can be determined by semi-micro-Kjeldahl method, the acidity is determined by neutralization method, the total phenol is determined by colorimetry, the tannin is determined by potassium permanganate method, and the pectin is determined by gravimetric method.
When measuring the light transmittance, the beer flavored vinegar can be diluted 10 times, measured with distilled water as a reference, and measured at a wavelength of 643 nm.