Harvest Issues and What machines Gregory James Uses to Process Grapes

November 14, 2019

Harvest Issues and What machines Gregory James Uses to Process Grapes

Harvest Issues?

Harvest has created a small interruption but the usual interesting challenges. This year has seen intermittent VERY hot days, spiking sugar levels together with very cool conditions, slowing things down. It is unusual to see the majority of the “first reds” not starting to come in until almost October. Then a couple rain events and unsettled weather in the last few days, well that starts the “mold clock” for susceptible varietals.

Given the right conditions, the molds and mildews will be visible in just a few days. This close to picking there are just a few treatments to consider. The “old standby” (sulfur dust) is reasonably effective, but can cause fermentations headaches (as yeasts are molds, they can be killed by the sulfur residues and if not killed the residues can cause some real stink in the fermentation). Other sprays are available with short acting compounds that vaporize and allow picks quite soon after.

The main problem is in the middle of harvest, the vineyard managers are really focused on picking grapes and keeping their crews busy. Switching to spraying delays all this and if the rains are ample, can make it difficult to get equipment through the vineyard (mud). So here again we see “logistics” playing a significant role in harvest.

One of the interesting effects of the weather slowing things down, causing delays is that it does get you later into the year. As things get later, the days get shorter, generally cooler, and the nights tend to get pretty cold. So, the plants are right on the verge of saying “we’re done”. Leaves begin to lose their green and may begin to color, indicating the plant is ready to prepare for winter. At this point if the fruit is not very near “maturity” (optimal flavors and aromas) it may be too late to hit the ideal and the considerations here turn to “as good as it can get”, pick it before it molds and that sort of thing.

Back to the Harvest

Most of the “whites” are in and nearing completion. White varietals like chardonnay and sauvignon blanc) are received at the winery where the standard practice now is to “whole cluster press”. There are two primary pieces of equipment involved (not including belt systems that allow “hand sorting” whereas the winemaking staff can dump grape clusters on a moving belt and by hand remove leaves and moldy fruit and things that shouldn’t be there, also there are now machines that can automatically “optically sort” using sensors, compressed air and algorithms to sort via computer).

 One machine is the DE-STEMMER. The machine is a horizontal drum with holes cut in its length and all around the circumference. In the centerline of the drum is an axle (think of it as a piece of pipe the length of the drum) the axle has a series of “paddles” running its length, but the “paddles” or “fingers” are welded to the axle in a “corkscrew” arrangement.

 

 As grape clusters fall into the machine, the “fingers” or “paddles” hook the clusters and draw them through the drum. The axle is spinning at a rate set by the winemaker. When the axle speed is correct, and the fruit in good condition, the “fingers” will fling the cluster against the drum. The berries can “pop off” and exit the drum via the holes, whereas the stems cannot. As the axle / fingers are in a corkscrew arrangement, the stems will get “walked out” the end of the drum. So, you have good clean separation of the berries from the stems, with little damage to the berries. The berries can be pumped by way of a specialized pump to the wine press.

The “wine press” is the machine that will squeeze the juice from the berries. The “press “is essentially a horizontal tank (drum) with a balloon inside running the length of the drum. A certain portion of the drum perhaps 1/3 of its circumference, is perforated (or has perforated “channels” inside the drum). Fruit is pumped or placed inside the drum and the perforated “doors” are locked in place with perforations “down”, and the balloon is inflated at a given rate. As the balloon inflates, it squeezes the juice from the berries. The process is repetitive, whereas the balloon is inflated, juice is allowed to flow, the balloon is deflated and the drum rotated a few times to allow the fruit inside to crumble around, then the cycle is repeated. After so many cycles 95% or more of the juice available has been captured and the squeezed-out berries and seeds (pomace) is dumped out for a new load of fruit. There are variations in the design of wine presses, but the mechanics are generally similar.

I mentioned “whole cluster” pressing the whites. This is where the white varieties, instead of “destemming” the berries from the stems (rakis), the “whole clusters” are placed in the wine press. It has been shown that the juice coming from this process tends to be cleaner, the stems acting as a bit of a “filter”. The trade off (there is ALWAYS a tradeoff) is “whole cluster” takes up a lot more space in the press, so considerably fewer “tons” can be processed in a press of a given volume. This obviously can make for long press days in the intent to get the highest quality juice.

Red varieties generally are sorted and destemmed, with the berries being pumped or gravity dumped to the fermenter chosen by the winemaker. Since most of the desirable things in reds come from the “skins” red wine fermentations include the berries, skins, seeds. When the fermentations are complete, the wine is drained from the “red tanks” the skins are “dug out” of the red fermenter and placed in the wine press to squeeze out the remaining wine. Red wine drained from the fermenter, and draining under gravity from the wine press is termed “free run” and is considered to generally be the highest quality wine from that lot. The wine squeezed via the press is termed “press wine” and is often collected separately. The press wine is usually evaluated for quality (aromatic, taste and tactile qualities) and may be introduced back to the free run.




Leave a comment


Also in Winemaking 101 with Mikael Gulyash

First Grapes Are In!
First Grapes Are In!

November 14, 2019

Continue Reading

Let's Talk about Picking Grapes
Let's Talk about Picking Grapes

November 14, 2019

Continue Reading

Discussion on Fermentation
Discussion on Fermentation

November 14, 2019

Continue Reading