Tips for wort boiling

During the brewing process, wort boiling is a complex process of physical and chemical changes. These changes are complicated, and it is difficult to take into account the favorable conditions of all changes at the same time. To a large extent, it needs to be mastered according to the type of product and operating experience.

Do you know why wort boiling is done?

Stabilized wort ingredients

1.Inactivation of enzymes

Destroying the enzymatic activity of malt and making it useless is mainly to stop the action of amylase and stabilize the ratio of fermentable sugar and dextrin in wort to maintain the consistency of wort components and fermentation.

2.Wort sterilization

By boiling, all kinds of bacteria, especially lactic acid bacteria, present in the wort are eliminated, so as to avoid spoilage during fermentation, so as to ensure the quality of the final product.

3.Protein denaturation and flocculation precipitation

During the boiling process, some proteins denatured by heat and flocculated and precipitated by combining with tannins are precipitated to improve the abiotic stability of beer.

4.Evaporate moisture

Evaporate the excess water in the mixed wort to concentrate the wort to the required concentration.

5.Leaching of hops

Hops are added during the boiling process of wort to dissolve the soft resin, tannins and aromatic components contained in the wort, so as to give the wort a unique bitterness and aroma, and also improve the biological and abiotic stability of the beer

Wort boiling also brings some other reactions

1.Lower the pH of the wort

When the wort is boiled, the pH value of the wort is further reduced due to the addition of hops, the formation of acid melanoids and the acidification of calcium and magnesium ions in the water, which promotes the precipitation of B-globulin in the wort and the finished product. The decrease of pH value of beer is beneficial to the biological stability and abiotic stability of beer.

2.Formation of reducing substances

During the boiling process, the color of wort gradually deepens, and some complex reducing substances such as reductone are formed, which enhances the antioxidant capacity of wort. big.

3.Undesirable volatile components are evaporated

During the boiling process, some original and newly formed vapour volatile bad taste components in the wort are steamed out, which also includes some hydrocarbon components with bad taste in the hop oil, such as geraniene and so on.

So what aspects should we improve the technical conditions of wort boiling?

1.Wort boiling time

To determine the wort boiling time, the wort mixing concentration should be mastered according to the wort boiling strength, so as to achieve the final required wort concentration within the specified boiling time.

The boiling time of wort has a great influence on the properties of beer. It is boiled under normal pressure. The boiling time of light beer (10%~12%) is generally controlled at 1.5~2h, and the dark beer can be appropriately extended; when the pressure is 0.11~012MPa Boiled under conditions, the time can be shortened by about half.

Reasonably prolonging the boiling time is beneficial to protein coagulation, improving hop utilization and the formation of reducing substances, but it is detrimental to foam performance.

Excessive prolongation of the boiling time is not only economically unreasonable, but also the quality of the wort will decrease. For example: dark wort, rough taste, reduced bitterness, poor foam, etc. For light beer, the impact is more serious.

The relationship between wort boiling time and concentration

2.Wort boil strength

When the wort is boiled, the water evaporated per hour is equivalent to the percentage of the mixed wort, which is the boiling intensity:

Boiling intensity (%, h) = (mixed wort quality L - final wort volume L)/(mixed wort volume L × boiling time (h)) × 100%

The level of boiling intensity is closely related to the thermal conductivity, shape, heating area, steam pressure, evaporation area of wort, and boiling method of the boiling pot.

Wort boiling strength and its evaluation

Under the same boiling time and pH value, the boiling intensity is the determinant factor affecting the coagulation of protein. With different boiling strengths, the transparency of wort is different, and the amount of coagulable nitrogen contained in it is also significantly different, but too high boiling strength is not very beneficial.

Relationship between wort boiling intensity and coagulable nitrogen content

3.PH value

pH value is closely related to protein coagulation, color and flavor of wort.

The protein in wort is the most unstable at its isoelectric point, and it is easy to coagulate and separate out. The isoelectric points of various proteins in wort are different, therefore, under different pH values, their precipitation also occurs first and then later. The ideal pH value is 5.2 when the wort is boiled, but it is difficult to achieve this value under normal circumstances, and it is even more difficult to achieve with hard water mashing. Its pH value decreases. When the pH value is in the range of 5.2~5.6, the protein can generally achieve a good degree of coagulation. The better the protein coagulation, the better the abiotic stability of the beer.

The interaction between polyphenols and proteins is also an important aspect to promote protein coagulation and precipitation. The lower the pH value of the boiling wort, the easier the polyphenols such as tannins and anthocyanins interact with the protein to precipitate out, thereby reducing the color of the wort, improving the taste of the beer, and improving the abiotic stability of the beer.

Although lower pH value is beneficial to protein coagulation, it is detrimental to the isomerization of hop α-acid, thus reducing the utilization rate of hops. It is ideal to control the pH value of the wort when it is boiled in the range of 5.2~5.4.