process consists in adding a substance which can be flocculated and
which, will on setting, carry down the suspended particles that produce
haze in wine or fruit juice.
Gelatine and Hydrolyzed Gelatine are particularly suited for red wine, beer and apple juice clarification where it reduces turbidity and decreases the astringency of final beverages without negative impact on suitable flavour components.
The gelatine is one of the most frequently used as agent for fining red wines in all wine producing regions.
Among all the products usable for wine clarification, it is the only one which is a food substance of excellent bacteriological quality and which allows:
- an unlimited shelf life in the dry state
- simple handling, especially for those qualities which are soluble in cold water,
- a rapid precipitation of the dense flocs
- bright clear wines without alteration of their color
The use of gelatine for fining white and rosé wines is less systematic, as it nearly always requires the addition of extra tannin in order to coagulate the naturally present protein and so avoid overfining.
Temperature is of main influence:
conditions favours flocculation and clarification. It has been
demonstrated that flocculation of wine is difficult at temperature
between 25 and 30°C or even impossible at least in white wine.
- Temperature between 14 and 16°C are common in wine fining
amount of precipitate at lower temperature could be explained by
co-precipitation of other components than polyphenol with gelatine or
RHC during the process
- Best results are obtained between 10 and 15°C for apple juice, while beers can be fined as low as 1 to 2 °C
A small difference of acidity is enough to affect the fining:
- For wine, the weaker the acidity, the quicker the flocculation
apple juice or young wines rich in protective colloids, the influence
of acidity is inverted: the more acid the apple juice, the better and
more rapid the clarification
apples, ripeness and variety of the fruits are of great influence: the
ripper the apples, the better the clarification. The more sour the
fruit and the lower in tannin, the smaller the amount of gelatine
required to get a satisfactory reaction
Overfining (excess of gelatine):
- The main risk is overfining (excess of gelatine), with some factors that favours overfining, as increasing acidity
- Overfining test: when adding a few drops of the tannin solution, there should be no precipitate, but the liquid becomes hazy
to proceed when a wine has been overfined: in case where the above
test reveals the presence of an excess of gelatine, together with poor
fining results, the use of bentonite is recommended to absorb the
proteins in excess
- Preliminary tests
should be made in order to determine the optimum dose of bentonite.
This operation must always be followed by either filtering or