OnTap Magazine

Developed in the 1960s by the German company Stabifix for the protein stabilisation of beer, silica gels and sols are made from natural sand which is heated to create a porous silica with a very high surface area for the physical adsorption of haze proteins. Their adsorption capacity is determined by pore structure, size, and moisture content. The latter determines if it is a xerogel (<10% moisture), hydrogel (<65%) or a hydrated xerogel (<35%). Silica sol is a suspension of silica particles and is applied as a pre-clarifier after mashing, or a clarifier at maturation. PVPP is the only sure-fire way of removing haze reactive polyphenols. It stands for polyvinylpolypyrrolidone, a resinous polymer that has a remarkably high affinity for chemical bonding with polyphenols, more so than the proteins present in the beer. It is insoluble and can easily be filtered out. However, it is expensive, which is why many brewers invest in regenerable PVPP or move to a combination of silica gel and enzyme. Proteolytic enzymes, including papain and proteases, will break down proteins but risk poor foam stability. A highly targeted approach is a proline-specific endopeptidase. This enzyme hydrolyses internal peptide bonds in proline-rich proteins involved in protein-polyphenol interactions. The latest such targeted enzyme named PEPfix ® was released by Stabifix in 2023. Also known as tannic acid, gallotannin is extracted from tree gall nuts and reacts with haze sensitive proteins. Generally added at maturation, ideally during the transfer, complexes formed are then filtered out. Interestingly, as a free radical scavenger, gallotannin is known to improve flavour stability by reducing oxidation. BEER STABILISERS & CLARIFIERS THE FOUR MAIN TYPES A long cold storage prior to packaging and the application of finings, stabilisers, clarifiers, and filtration will remove haze and increase colloidal stability. Using raw materials with lower protein content in the recipe will help, as will avoidance of over hopping and heavy late hopping. Yeast in suspension can create a stable haze in certain conditions, but for a clear, haze-free beer good yeast flocculation is key. Beer stabilisers reduce either haze- sensitive proteins or haze-reactive polyphenols toenhanceabeer’s colloidal stability. They complement the natural beer stabilisation and clarification effects of the brewing process itself, where haze proteins and complexed polyphenols are removed along the way. Stabilisers further enhance this process but do so in a targeted way. Finings such as isinglass and gelatine will remove yeast and protein haze, but they are not so popular. These processing adsorbents are added during maturation or filtration. There are four stabilising and clarifying technologies that will increase the colloidal stability of beer and enhance shelf-life: silica gel and silica sol, PVPP, enzymes, and gallotannin (tannic acid). How and how much stabiliser, clarifier and enzyme to use depends on several brewing parameters including the beer recipe and style, the original gravity, oxygen levels, maturation temperature, and the level of endogenous enzymes. The great advantage is that these applications do not impact beer flavour, foam or colour. Regardless of whether a haze is intended or accidental, it is important for brewers to understand the various precursors and causes of haze and their respective consequences for ageing, foam and colloidal stability and product life as well as the various methods and applications available for ensuring that the desired haze is only the product of the desired cause. Perhaps brewers should also be prepared for the inevitable day when the discerning drinker decides that crystal clear beer is the next big thing. ACHIEVING COLLOIDAL STABILITY EXTENDING A HELPING HAZE TYPE 01 TYPE 03 TYPE 02 TYPE 04 20 | Autumn 2024 | ontapmag.co.za