AU2018100786A4 - Conversion treatment for downy mildew affected ripened wine grapes into an alcoholic potable beverage. - Google Patents

Abstract

Abstract A post-harvest treatment of mature, ripened, wine grapes affected by downy mildew (Plasmopara viticola) to produce an intermediate useful in manufacturing a potable beverage such as fortified wine, liqueur or brandy. The treatment includes steps of immersing the grapes in industrial grade ethanol, sparging the grapes, high-pressure spraying the grapes, stripping the grapes, soaking the grapes, filtering the soaked grapes, adding yeast (EC 1118) to the solution for fermentation and then distillation.

Description

The treatment of downy mildew affected ripened grapes requires the following steps. 1. Harvesting and immersing dry surface grapes in industrial grade 70 % ethanol for 1-2 minutes. 2. Drain off the ethanol, retain run-off in a separate vessel, then sparge spray the grapes with 50% volume of water which was used in the original ethanol immersion. This water to be ambient temperature fresh water and retain the drained run off in a different vessel. 3. Use the initial collected concentrated alcohol several times until its alcohol strength falls to 50%, then stop using this solution for grape sterilisation. Subsequently, mix it with the water/alcohol rinse water from previous batches and distil it in a reflux still to 80-90% alcohol concentration for re-use as a sterilising agent. 4. High pressure spray, the above treated grapes with fresh ambient temperature water, drain (almost drip dry) and discard the water. This will remove most dead mildew tissue from the surface of the grape's skin. Care must be taken not to damage the grape's waxy cuticle or exocarp with the pressure spray. 5. Explanatory note: The mildew's dead aseptate mycelium will remain inside the grape and may produce off flavours if the grape is pressed in the usual manner for wine fermentation. Therefore: - 6. Carefully strip the grapes off their stems in a food safe manner, without damaging their exocarp, then quickly soak them in potable 20-30% alcohol. As the grape cuticle and exocarp has very few stomata, in osmotic terms it becomes an efficient semi-permeable membrane. Grape sugars and flavonoid solutions will pass through this membrane, because fruit juice's specific gravity is higher than the diluted ethanol. Most of the alcohol will enter the grape. The soakage time to continue until the external to the fruit solution's alcohol content reaches 5-10%. This concentration depends on the envisaged alcoholic beverage type and storage capacity practicality. The alcohol within the already surface sterilised fruit will preserve it during any prolonged storage soakage time. 7. Once the required solution alcohol content is reached it is filtered, then a high alcohol concentration tolerant hydrated yeast such as EC 1118 is added. The solution is then fermented and subsequently distilled in the usual manner, to make a potable beverage such as brandy, fortified wine or a liqueur. 8. The remaining alcohol desiccated fruit, containing the dead mycelium is then crushed, diluted with purified water (no chlorine) and distilled to recover the alcohol. This distillate may only be suitable for subsequent fruit sterilisation. Alternatively, with double/triple redistillation through a column reflux still, adverse mildew flavours could be removed to make potable ethanol. However, the concentration of any carcinogenic ethyl carbamate should first be assessed. If E.C. levels are too high, then the distillate only be used to sterilise the fruit as described in step 1. above.

Claims (1)

1. Patent Claim. A post-harvest treatment of mature ripened wine grapes that have been affected by downy mildew (Plasmopara viticola), to make a recoverable commercial commodity for fermentation then distillation into brandy or fortified wines.