Beyond the important commercial aspect of a beer’s visual appearance, the stakes for brewers are the duration and efficiency of the fermentation and clarification process.

Beyond the important commercial aspect of a beer’s visual appearance, the stakes for brewers are the duration and efficiency of the fermentation and clarification process. In an increasingly competitive world, with ever-rising production costs, breweries can’t afford not to think about their brewing processes.

Contrary to what the English name for the boiling clarification process, “kettle fining”, might suggest, the main benefits of this practice lie in the ability to clarify more effectively during fermentation. This method shortens fermentation and storage times by several days.

We’re going to review the use of carrageenans, also known as “kettle fining” or “cooper fining”, in the brewing process.

Composition of undesirable particles in brewing wort

Beer clarity is compromised by yeast cells and non-microbiological particles (NMP). Yeasts are mainly eliminated by their natural flocculation during fermentation, or later in the process of clarification, centrifugation or filtration, which we’ll cover in another article. The main problem is caused by PNMs: proteins, often associated with polyphenols and other molecules such as lipids, carbohydrates and/or metal ions.

Advantages of using kettle finings

• Reduces the time needed to clarify beer
• Turbidity reduction (by a factor of 6) ref1
• No negative impact on the qualities of the finished beer
• Reduces losses and the use of materials (filters, filtration media) during filtration or centrifugation.
• Improved yeast quality for reuse (separation of cold break from yeast in fermenter cone)
• Energy savings through reduced use of refrigeration
• Clearer beer
• Longer shelf life

A word about Stokes’ law

Particles settle naturally under the influence of gravity, as described by Stokes’ law, and as you’ve probably already observed. According to this law, the sedimentation rate of a spherical particle is directly proportional to the difference in density between the particle and the liquid medium, to the acceleration due to gravity (hence the usefulness of the centrifuge), and to the square of the particle radius, and inversely proportional to the viscosity of the liquid. So, if the wort or beer is left to rest long enough, it will clarify itself; this is the basis of the lagering process.

Here is the formula of this law in the context of brewing:

• v = sedimentation rate of a spherical particle
• ρ₁ = particle density
• ρ₂ = density of the medium (wort or beer)
• r = sphere radius
• g = acceleration due to gravity
• η = medium viscosity

The aim of using “kettle finings” is therefore to increase the particle size (r = radius of the sphere), which is multiplied by the square, massively increasing the speed of sedimentation.

Origin and control of particles in the brewing process

Non-microbiological particles (NMP) are produced and eliminated at five stages of the brewing process. Understanding how these steps affect particle formation and removal enables the brewer to control the process better to achieve an optimal and consistent level of particles in the beer, leading to a more efficient and consistent clarification process, whether the final product is keg, can or bottle.

1. Milling: The milling of grains generates numerous particles of fine dust and husk. These are generally eliminated when the mash is filtered. However, if the wort is not recirculated through the mash bed before discharge, or if excessive pressure is applied to the filter, these particles can end up in the wort. A high final mash temperature promotes particle coagulation, but can also increase must viscosity, counterbalancing the beneficial effects on flow rates. Optimum adjustment of the mill is one of the keys to achieving both correct output and efficient filtration in an acceptable time. We can help you fine-tune your grinder, so don’t hesitate to contact us.
2. Boiling the must: During boiling, thermal denaturation causes proteins to coagulate to form the hot break. Efficient coagulation is favored by a high wort pH, the presence of sufficient protein and good boiling conditions (minimum 102°C, sea-level atmospheric pressure). If coagulation is ineffective, particles may remain suspended and be transported to subsequent brewing stages.
3. Must cooling: During cooling, wort proteins interact with polyphenols to precipitate as cold breaks. These very fine particles settle slowly and can end up in the finished beer. Cold-break formation is temperature-dependent, below 20-30°C.
4. Fermentation: a number of physical changes take place, producing and facilitating the removal of particles. Yeast reproduction begins, increasing the number of yeast cells in the beer and lowering the pH, which favors the interaction of proteins and polyphenols to form NMPs. This removes 45-65% of soluble proteins and 20-30% of soluble anthocyanogens from the must.
5. Beer cooling: At the end of fermentation, when the beer is cooled, the yeast flocculates and settles to the bottom of the tank, taking other particles with it. Cooling also causes proteins and polyphenols to interact further to form more PNMs. The density of PNMs is estimated to be intermediate between that of beer and yeast cells.

It is generally accepted that it is best to remove particles at as many stages of the brewing process as possible. This results in a more efficient and consistent process. For unfiltered beer, this practice results in a clearer beer than if all the clarification were left to the post-fermentation stage. For filtered beer, this means less use of consumables, and fewer post-filtration problems.

Origin of “kettle fining” aka must clarification agents

Must clarifiers have been used for many years, with raw materials mainly derived from red seaweed, generally of the Chondrus crispus genus. Until the 1960s, Irish Moss was the main material used, and is still used today in a small number of breweries.

In the 1960s, developments refined the source of seaweed, and clarifying agents as we know them were produced. Initially, these materials were rather limited in their refinements, but showed a significant performance advantage over raw Irish Moss.

In the 1980s, a major breakthrough was achieved with pure, refined carrageenans. These materials are totally water-soluble and highly active.

The new, and still current, phase of clarifying agents is the use of granular materials from a different algae source. The new materials are semi-refined algae of the Eucheuma genus. These are the products we offer under the Protafloc brand from Murphy & Sons.

Action of Protafloc, our must clarification agent

Protafloc contains large, negatively-charged polysaccharides called kappa-carrageenans, which bind to the positively-charged proteins in the cold break as it forms. The resulting particles are relatively larger and settle, falling more rapidly to the bottom of the fermenter. The addition is simple and easy, carried out ten minutes before the end of boiling.

Factors influencing the performance of must clarifiers

Several factors have been identified as influencing the performance of must clarifiers:

• Dosage: As the dosage rate increases, more particles are removed, wort clarity improves and the amount of sediment produced increases. The optimum dosage rate is the one that offers the best cl

arity while minimizing sediment volume. Too high or too low a dosage will be less effective, or even have a negative effect. We can help you determine the optimum dosage.

• Timing of addition: Early addition of agents is essential to completely dissolve kappa-carrageenan molecules, which do not dissolve below 60°C. Protafloc should be added 10 to 15 minutes before the end of boiling.
• Hot wort clarity: It is generally accepted that wort clarifiers have no significant effect on hot wort clarity, although some brewers report measurable benefits. However, the clarity of the hot wort has a considerable influence on the performance of the wort clarification agents.
• Wort pH: Wort pH has a marked effect on clarification performance, with a pH of around 5.0 required for effective clarification. Musts with a pH below 4.5 clarify much less well. Significant variations in clarification performance are observed according to must pH, with sometimes a difference of just 0.3 pH units significantly affecting levels of non-microbiological particles (NMP).
• Malt variety, quality and harvest year: Malt variety and quality play a crucial role in clarification performance. Musts prepared from different malt varieties under identical conditions may require different clarification rates for optimum performance.

These factors show the importance of understanding and controlling brewing conditions to optimize the effectiveness of clarifying agents and ensure the quality of the final product. We will be happy to provide you with any information you may require on kettle finings and their use. Don’t hesitate to contact us. We offer Swiss professional breweries the resources and expertise they need to improve their brewing processes. Contact us, no obligation

Ref1: Effects of Wort Clarifying by using Carrageenan on Diatomaceous Earth Dosage for Beer Filtration by Aleksander Poreda, Marek Zdaniewicz, Monika Sterczyńska, Marek Jakubowski and Czesław Puchalski.