Resumen de Predicting protein haze formation in white wines

Jacqui McRae, V. Barricklow, K. F. Pocock, Paul A. Smith

• Background and Aims Wine protein haze formation is commonly predicted by a heat test; however, the conditions used in the test can vary widely between laboratories. Here, we investigate the influence of heating and cooling conditions on heat test results.

  Methods and Results White wines were heated at 80°C for a time that varied from 0.5 to 6.0 h and then cooled for 0.5–18 h at either 0, 4 or 20°C. The turbidity was measured before heating and after cooling. Longer heating times, longer cooling times and a lower cooling temperature all increased the amount of haze produced in the heat test. Bentonite fining trials with eight white wines indicated that after 2 h heating, cooling either at 4°C for 18 h, 0°C for 3 h or 20°C for 3 h had no impact on the predicted dose. Heating for 6 h with 18 h cooling at 4°C (24 h test) generally increased the predicted bentonite dose by up to 0.3 g/L compared with heating for 2 h. Wines fined at the bentonite dose recommended by a 5 h test or a 24 h test were generally clear after storage at 17 or 28°C for 12 months while the unfined Control wines generally became hazy.

  Conclusions Wines heated for 2 h at 80°C and subsequently cooled for 3 h at 20°C (5 h heat test) enabled the repeatable production of haze and bentonite fining dose.

  Significance of the Study Heat tests used in the wine industry need to include consistent heating and cooling conditions for reliable results and can be achieved in less time than previously recommended.