Mechanism and Control Measures of Beer Aging Reaction

Beer aging is one of the common flavor defects of beer, and aging reaction is an extremely complex process affected by many factors.

Beer aging has always been an important issue affecting the taste of beer. The aging taste of beer mainly comes from alkenal carbon-based compounds, and alkenal compounds can be expressed by TBA value. Today, we will focus on the control measures from the process of mashing wort:

∟The saccharification process before boiling⊿

1. Try to make saccharification in a closed environment, and the mash and wort are transported from the bottom of the pot and tank;

2. Select the special pouring mash pump with low lift and large flow to ease the conveying, reduce the turbulent flow of the mash to absorb oxygen during transportation, and stop the pump in time when the mash is conveyed.

3. Pipelines, pumps, seals, valves, etc. should be sealed without any leakage.

4. Before the mash enters the filter tank, fill the filter plate with deoxygenated hot water at a suitable temperature to drive away the residual oxygen in the bottom of the filter plate and the wort collector. The temperature of the wort should be controlled at 76~78 degrees Celsius, and the pH value of the water should be less than 6. Because the unreasonable control of the water temperature and pH value will lead to the leaching of bitter substances, polyphenols and silicate substances in the wort, which will affect the taste of beer.

5. Strictly control the filtration quality of the mash, because the filtration quality of the mash affects the content of free fatty acids in the wort. During the boiling process of wort, unsaturated free fatty acids can produce aging flavor aldehydes or their precursors through thermal catalytic oxidation. These precursors are continuously oxidized during beer storage to form aging flavor aldehydes, so it is necessary to strictly control the wort. Turbidity.

6. Shorten the filtration time and control it within 2 hours. Because the presence of peroxidase in the filtration process will promote various enzymatic reactions, resulting in wort oxidation.

7. Reduce the stirring times of the mash and reduce the stirring speed.

∟When the saccharification process boils⊿

1. After filtration, the wort at 76 degrees Celsius is first heated to 92 degrees Celsius through a plate heat exchanger with steam as the heat source, and then enters the boiling pot. The wort is immediately heated and boiled to reduce furfural compounds and reduce the aging of beer.

2. Appropriate control of boiling time can reduce energy consumption and reduce the generation of harmful substances, because heat load (such as high boiling temperature, long boiling time, etc.) has a greater impact on the formation of beer aging substances, and it is necessary to prevent Occurrence of local overheating. Because of excessive heat load and too long boiling time, Maillard reaction will be aggravated, and melanin-like substances will be formed, which will affect the content of aging flavor substances in beer, and also increase the color and flavor stability of beer.

2. Adjust the pH value of the wort when it is boiled to make it as close to the isoelectric point of the protein as possible to accelerate the aggregation and precipitation of the protein in the wort.

3. Shorten the time of saccharification at high temperature and avoid excessive oxidation of polyphenols in the wort during the saccharification stage

∟After the saccharification process is boiled ⊿

1. After the wort is boiled, reduce the inhalation of oxygen when pumping into the rotary sedimentation tank. The distance between the wort pump and the bottom of the rotary sedimentation tank is greater than 2 meters to avoid cavitation.

2. The speed of the wort entering the gyratory sedimentation tank should be less than 5 m/s to ensure that the difference between the entry speed and the gyratory speed is as small as possible, and to ensure that after all the wort enters the gyratory sedimentation tank, the gyratory speed drops rapidly, and the shear force is as fast as possible. disappear, in order to facilitate the compact accumulation of thermal coagulation.

3. The wort precipitation time should not be too long, otherwise the DMS precursor will be decomposed into DMS, and more Maillard reaction products will be formed.

4. Speed up the cooling to shorten the heat retention time of the hot wort in the rotary sedimentation tank, reduce the heat load and reduce the TBA value of the wort.

In fact, the formation of the aging flavor of beer is not only caused by the oxidation of oxygen in beer. In fact, many craft brewers will find that even if the oxygen content of bottled beer is reduced to a very low level, the beer will still be stored during storage. Aged flavors appear. This is because the redox reactions in beer are essentially electron transfer, and some oxidations do not involve the direct participation of molecular oxygen. Therefore, in order to improve the anti-aging performance of beer, in the process of beer production, as many reducing substances as possible should be retained in the beer, and the precursor substances that produce aging flavor should be reduced as much as possible.

In the final analysis, the best way is to prevent excessive oxidation in the early stage of brewing, fundamentally improve the anti-aging performance of beer, and prolong the fresh-keeping period of beer.