WINETECH Technical Yearbook 2020

zyme-pasteurisation combination. Carra- geenan is made from red seaweed and is a renewable and natural product. Recent research indicated that it is more selective than bentonite to remove proteins with- out also removing other desirable wine constituents. It is already available, but the approval in wine markets is still out- standing. Flash pasteurisation can be an acceptable alternative for certain wines, without experiencing wine losses. No ap- proval is required for it, but special, expen- sive equipment is required and its energy consumption is also high. The heating of grape juice in the presence of aspergillo- pepsin enzymes can deliver a heat stable wine, which make these enzymes a viable alternative for bentonite. Medium-term alternatives include grape seed powder and membrane technology. Grape seeds contain high concentrations of polyphenols, which can bind proteins. After grape seeds have been toasted for 10minutes at 180°C they can be added to grape juice to bind the turbidity-forming proteins. The juice is then racked and fermented, which will lead to a protein-stable wine. Initial experiments have been promising, but more information needs to be obtained regarding the influence it will have on the sensory characteristics of the wine. Membrane technology comprises the transfer of a protein-unstable wine on one side of the membrane to its other side, where the wine will be protein stable. The retentate

Bentonite is a popular fining agent.

PVPP

Albumine

Bentonite

Carbon

Bentonite alternatives

percentage lees it produces and the result- ing lees also contribute considerably to the solid waste of cellars. Bentonite can physically be used in powder or granular form and chemically as Na or Ca form. The different forms have different properties regarding lees percentages and the efficiency of protein stabilisation. Winemakers do however agree that an alternative without the present disadvantages of bentonite will be beneficial. The potential alternatives can be divided between present, medium-term and long-term alternatives. The present potential alternatives include carrageenan, pasteurisation and an en-

OCTOBER 2020

CHARL THERON: Private consultant KEYWORDS: Bentonite alternatives, protein stabilisation

but is mainly used for the protein stabili- sation of white wine. Its use does however have certain disadvantages. It causes con- siderable product losses due to the high

Bentonite is probably one of the most com- monly used additives during winemaking. It can be used together with other fining agents for the clarification of juice or wine,

WINETECH TECHNICAL YEARBOOK 2020 172