For many people, when they first encounter craft beer, they are often somewhat puzzled as to why it is cloudy. The commercial beer they used to drink was always clear. What has happened? What causes one type of beer to be cloudy whilst the other remains clear? Let’s examine the reasons behind the difference in clarity between craft beer produced by a 1,000-litre two-vessel brewing system and beer produced by large industrial breweries.

The primary factor contributing to the cloudiness of beer brewed using a 1,000-litre two-vessel system is the breakdown of proteins in the malt during the brewing process. Brewers who have used a 1,000-litre two-vessel beer mashing system are well aware of the principles involved. During the mashing process, proteins, sugars and starches are broken down within the malt. The key component of craft beer is the production of a mature brew that has not undergone pasteurisation or filtration, is rich in active yeast, and remains unfiltered.

A 1,000-litre two-vessel beer mashing system can produce high-quality beer, but certain considerations must still be observed when using it.

Therefore, if you wish to brew high-quality craft beer, you must pay attention to numerous details.

1. Wort composition. As the system produces only a small amount of alcohol, the acid content in the wort should be controlled at (18 ± 2) mg/L. The malt should contain sufficient acids and easily fermentable carbohydrates. If the proportion of adjuncts is too high or too much sucrose is added, this often leads to a deficiency of alpha acids in the malt, resulting in increased alcohol content.

2. Yeast dosage. A dosage of (1.5–1.8) × 10¹⁷ cells/mL is considered appropriate. A higher initial yeast cell count, with relatively fewer cells, helps to reduce alcohol formation; conversely, if yeast cells proliferate excessively, this readily leads to increased alcohol production. In actual production, the yeast cell count is generally kept below 4.

3. Fermentation method. Combined tank fermentation (primary fermentation in conical tanks followed by secondary fermentation in traditional fermentation tanks) increases total alcohol content by 2–25% compared to conventional methods. Regardless of the method employed, any measures to accelerate primary fermentation will increase alcohol content.

4. Fermentation temperature. High dissolved oxygen levels in the wort and high-temperature fermentation both promote yeast proliferation, correspondingly increasing alcohol production; therefore, process measures such as low-temperature primary fermentation and high-temperature secondary fermentation can be adopted. Pressure fermentation also helps to reduce alcohol formation.