Silica Gel for Food, Drink and Pharmaceutical Products

The use of silica gel in the food, drink and pharmaceutical industries is broad. Common examples include the use of silica:

• As flow agent (i.e. to aid powder flow) in the production of pharmaceutical tablets and powdered food products
• As a clearing agent for essential oils, refreshments and liquors
• To clarify and to stabilise beer (i.e. to achieve colloidal stability and prevent chill haze)

We can supply the following products, details of which can be found below.

Silica gel for beer stabilisation and clarification

Our beer stabilising silica gels comprise highly selective adsorbents that are specifically manufactured for breweries. Due to their unique surface characteristics and pore structure, it is possible to selectively adsorb proteins that cause haze in beer. Thus, beer stabilisation can be achieved without damaging the proteins necessary for an attractive head of foam.

The silica is nontoxic, tasteless, flame-resistant and non-explosive. It is safe to store and to use in the brewery. Although these products are harmless to the human body, it should be noted that none remain in the final product because they are removed entirely during the filtration stage. The result is a brilliant beverage that retains its clarity during extended shelf storage - but how do these products work?

Colloidal haze, which is attributed to some proteins, phenols and carbohydrates,^1-3 occurs naturally during storage. It disrupts the clarity of beer and is normally seen by the consumer as a lack of freshness in the product. Academic research has led to the understanding that the two major constituents, haze-forming proteins and polyphenols, interact with each other to afford the colloidal particles.^4,5

Another model⁶ stipulates that oxidation of flavanol oligomers during storage leads to chill and permanent haze development. As the flavanols polymerise, they bridge a number of proteins to afford colloidal particles. At first this is only visible as chill haze, but with further polymerisation the colloidal particles become larger and so permanent haze is observed.

Silica gel is capable of adsorbing the proteins that give rise to colloidal haze and chill haze. These surface-adsorbed proteins enter the pores of the silica, in what is known to be the rate-determining step of the process.⁷ Thus, pore structure plays a major role in tuning the affinity of the silica gel towards haze-causing proteins, whilst protecting the hydrophobic polypeptides which give rise to the favourable head of foam.^2,8

References

1) Anger, H.-M. (1996). Assuring non-biological stability of beer as an important factor for guaranteeing minimum shelf-life. Brauwelt Int. 14(2):142-150.

2) Bamforth, C. W. (1999). Beer haze. J. Am. Soc. Brew. Chem. 57:81- 90.

3) McMurrough, I., Madigan, D., Kelly, R. J., and O’Rourke, T. (1999). Haze formation and shelf life prediction for lager beer. Food Technol. 53(1):85-62.

4) Siebert, K. J., and Lynn, P. Y. (1998). Comparison of polyphenol interactions with polyvinylpolypyrrolidone and haze-active protein. J. Am. Soc. Brew. Chem. 56:24-31.
5) Siebert, K. J., Carrasco, A., and Lynn, P. Y. (1996). Formation of protein– polyphenol haze in beverages. J. Agric. Food Chem. 44:1997- 2005.

6) O’Rourke, T., Ianniello, R., McMurrough, I., and Springle, A. (1998). The role of tannoids in the colloidal stabilization of beer. In: Proc. Conv. Inst. Brew. Asia-Pacific Sect., 25th, Perth, Australia, pp. 143- 146. Institute of Brewing, London, U.K.

7) Rehmanji, M., Gopal, C., and Mola, A. (2005). Beer Stabilization Technology - Clearly a Matter of Choice. MBAA TQ. 42(4):332-338

8)Siebert, K. J., and Lynn, P. Y. (1997). Mechanisms of beer colloidal stabilization. J. Am. Soc. Brew. Chem. 55:73-78.