Wednesday, October 24, 2012

Refrigeration in the Wine Industry

No, not getting the bottle of white wine cold before drinking but keeping the juice (must) and wine cool during the production process ie. grape delivery, crushing, fermentation, pressing, transfer, storage.
Modern wineries use refrigeration units to keep their white fermenting musts cool.
This encourages desirable aroma and flavour compounds. The target is usually between 10°C and 16°C.
The temperature of grapes coming in from the vineyard during harvest in summer can be a lot higher than this, so cooling is almost always necessary.
But what about the more primitive 'Vin de Garage' operations like mine?
How do I keep the ferment cool without going to a huge (and unwarranted) equipment expenditure?
Adding dry ice has been suggested. This would have the additional advantage of adding carbon dioxide as an oxidizing protectant but it always involve the danger of taste taint and it is not the safest thing to handle (burns and asphyxiation).
Putting a small tank inside a larger one and filling the void with an ice or ice/salt mix has been suggested together with insulating the outside tank with a flexible foam sleeve. Logistically all possible but no real temperature control.
Adding ice in containers to the actual must is another suggestion. This could be viable as long as the containers were sanitized and secure so any melt water did not get into the wine.
Searching on the net I found plenty of information on the affects of ice addition to water and the resultant cooling affect.
One formula was able to calculate final temperature based on original weight and temperature of water and weight of ice added.

I decided to test this out. So I added a specific amount of ice (1000g) contained in a sealed mineral water bottle to a specified amount of water (6000g) and noted the temperature drop. It fell 6°C in one hour and remained there for about 3 hours before starting to rise.
The result was considerably higher than the formula predicted . I guess ambient conditions were to blame.
However this method is indeed worth pursuing and I will try a full scale experiment with water in a wine tank soon.
Temperature could be adjusted by the addition and removal of bottles. Maintenance of the required temperature would depend on the number of bottles required. That is the great unknown at this stage.

Sunday, October 14, 2012

An Unseasonal Weather Event

We had 24 hours warning that an intense low pressure system was forming off the coast and that there would be torrential rain and gale force winds.
So we spent the day battening down, cleaning out gutters and putting things away.
And wooooosh......... in it came!
Over 300mm (12inches) of rain in 36 hours accompanied by 95km/hr wind gusts.
In a tropical zone it would have been a category 1 cyclone (hurricane).
Our creek soon broke its banks and flooded the bottom paddock. Some trees came down.
The surf was huge.
Up in the mountains there was snow down to 700m. Some roads were closed.
But it went as quickly as it came.
And amongst it all a new calf was welcomed into the world. Mother and son are both doing well.
Back to typical spring weather now, sunny, warm and humid.
It's a bit soggy around here but won't take long to dry out.

                      All the grapes needed respraying after all the rain including the Cabernet Sauvignon for the first time.
Again with copper and sulphur but this time with a downy mildew curative in combination just in case.
I use phosphorous acid (Agri-fos 6oo) as a downy mildew curative. It is the world’s only fully systemic downy fungicide, moving easily up and down in the vascular fluid of the vine after rapidly moving away from sprayed tissue.
PA is usually not used in commercial vineyards which export wine. Most countries have a strict MRL (maximum residue limit) which can be met with proper applications but both China and Canada have a no tolerance level. Keeping grapes separate for different wine export markets is almost impossible so it's easier not to apply the chemical at all.
It's a very effective fungicide and the Australian wine industry is working with both countries to have reasonable MRLs introduced. I believe they are making some headway.

Wednesday, October 10, 2012

Even More Spring Flowers





Wednesday, October 03, 2012


There are four species of Waratah. They belong to the Proteaceae family which is a group of flowering plants found in the southern hemisphere. Members of that family native to Australia include Banksias, Grevilleas and the Macadamia nut.
The Protea from South Africa is also a member.
The best known Waratah is probably Telopia speciosissima which is the state flower of New South Wales.

                  They grow wild on 3m high shrubs with typical leathery leaves in the sand stone gullies around Sydney.
They are very sought after as cut flowers with prices reaching $20 a stem.
For that reason, they are now hard to find in the wild due to poaching. Even plants growing in private gardens have flowers stolen off them.
Stealing flowers in the wild threatens the survival of some populations. If Waratahs are torn off, they will not flower through the next season and seeds are prevented from returning to the bushland, They take five years to flower from seedlings. The species has already disappeared from some of the more 'rural' suburbs.

Our vineyard friends down the road have one shrub. This year it has been flowering profusely.
Telopia means 'seen from afar' and speciosissima means 'beautiful'.

Monday, October 01, 2012

Vintage 2013 Continues

Warm weather and some sporadic rain have encouraged pretty rapid shoot growth of the Pinot Noir.
In viticulture talk it had reached growth stage E-L 12 ie. five to six leaves unfolded with inflorescence clearly visible.
The E-L system designates the phenological stages of grapevine development described by Eichhorn and Lorenz and there are 47 of them.
A simpler system is the modified Baggiolini one which is limited to 15 stages ie. A to O.
In that case the Pinot Noir was at F
It was time for the first spraying.
In my opinion it is essential in the early stages of growth to protect the vines from both downy and powdery mildew, especially in a warm maritime climate like ours.
Then again there is another school of thought that believes only curative sprays should be applied ie. spray only after a weather event that would be conducive to the development of those diseases. However while there are suitable curative sprays for downy mildew, there are none that are really effective for powdery mildew.
After last year's disaster with a modified version of a curative spray program, it was a no brainer to apply protective sprays this season.

Against downy mildew (Plasmopara viticola), I use the copper based spray copper oxychloride. The dried copper spray droplets sit on the leaf surface and slowly release a supply of cupric ions.
These are picked up by the fungus spores and travel through their cell walls to eventually disrupt cellular enzyme activity. Copper sprays are not systemic ie. they don't get into the plant's sap system and get translocated around the plant. They are surface sprays. Droplets remain static so as the vine grows, additional sprays must be applied to protect new growth as well as replenishing the already sprayed areas. Under normal circumstances this is done approximately every two weeks. Rain events shorten the spray intervals.
Against powdery mildew (Uncinula necator), I use a micronised wettable sulphur powder.
Despite sulphur usage dating back some 180 years the mode of action still remains unclear.
Actual contact of the sulfur particle with the fungus is necessary before fungicidal action can occur. There is some debate as to whether vapour inhibits spore germination. The jury is still out on that one.

                      A sulphur spray forms a protective barrier on the plant surfaces. This barrier kills fungi by interfering with cellular respiration preventing it from accumulating the materials and energy it needs to survive.
Sulphur also keeps the vines clear of blister mites (Colomerus vitis). Although I have never seen them here, they are in the area.
Blister mites feed on the under-surface of leaves and cause very obvious blisters on the upper surface of leaves and white or brown hairy growths within the raised blisters on the lower surface of leaves.
Damage by the mite is more unsightly than economically consequential.
As with copper, sulphur sprays need to be reapplied on a regular basis.
Both copper and sulphur can be mixed and applied at the same time.
A little care has to be taken with sulphur sprays. Application at temperatures above 30C and high humidity can lead to phytotoxicity problems on young growth.
As far as shoot development is concerned, the Semillon is a little behind the Pinot Noir and the Tempranillo slightly behind the Semillon.
We are just now getting Cabernet Sauvignon bud burst.