Step #2: Harvest & Grape Sorting
This page covers the harvesting of grape bunches in the field, sorting out bad bunches and debris, destemming the bunches and then sorting out remaining debris among the grape berries. The result is clean grape berries in fermentation tanks.
Picking the Grapes
A manual harvest involves organising a large enough picking crew so that all the grapes can be harvested during the morning hours before it gets too hot. Exposing picked grapes to sunshine and heat for more than 1-2 hours can severely reduce their quality. We usually organise a group of a dozen or so friends to show up in the morning, hand them 5-gallon buckets and clippers and get the job done within a few hours. The bribe is a good lunch.
In 2013 we started to record the crop volume [lbs] by row. In 2014 we estimated the crop load for each vine and then recorded the crop volume for each vine at harvest (except for low yielding vines which we combined into groups of 2, 3, 4 or 5 plants). In 2015 we recorded crop loads for each vine but in 2016 returned to recordings per row.
These charts show the harvest volumes over the last 20 years. For each block, we show the gross yield in the field and how much ended up in the fermentation tanks.
Three points of note. First, we only started making wine in 2009, before we sold all our grapes. Second, the yield in the Cabernet Sauvignon blocks dropped significantly after 2009 because we battled a self-inflicted Eutypa infection of the vines. It took us almost 10 years to recover from that mistake. Third, beginning in 2016 the 4 blocks in the upper vineyard start producing Merlot, Cabernet Franc and Petit Verdot.
Sorting, Destemming & Crush
Bunch sorting is a labour-intensive manual process taking as long as picking. We pour buckets of grape bunches one by one on a table and people sitting around the table sort out by hand all the irregular, infected or damaged bunches and berries. Good bunches and grapes are passed on to destemming. Bad material is discarded. The percentage of the discarded material varies between 2% in a good year (e.g. 2014) and >25% in a bad year (e.g. 2011, 2015, 2017).
For small harvest volumes, below 300 lbs, we use a single Bunch Sorting table from which we throw clean bunches into a Destemmer. The destemmer detaches the berries from the stems. The grape berries fall on a Berry Sorting grid from which we scoop the clean berries into a small fermentation tank. This is a two-person operation. We use a Delta E1 Destemmer from Bucher Vaslin (http://bvnorthamerica.com/wp-content/uploads/2013/07/Delta_E1_ang_avril_2007.p°F) which can efficiently process 1 ton of grapes per hour.
For medium-size harvests (300 – 1200 lbs) we add another bunch sorting table and a Grape Elevator which we use as platform for berry sorting, and we use a Crusher which crushes the berries before they fall into the Fermentation Tank. The grape elevator was manufactured by P&L Specialties, Santa Rosa, CA ( pnlspecialties.com ). The Crusher is a modified electric grape crusher from Williams Brewing, San Leandro, CA ( williamsbrewing.com ). This is a 5-8 person operation.
For larger harvests, we add another bunch sorting table, and we mount the destemmer on top of a TRV15 Vibration Table from Bucher Vaslin, (http://bvnorthamerica.com/wp-content/uploads/2013/07/TRV20-35-50_ANG_2006-11.p°F) on which we sort out bad berries and MOG (Material Other than Grapes). Under the sorting table, a pan collects juice from damages grapes and MOG. That juice can be filtered and poured into the fermentation tank, or it can be counted as part of the “Saignee” and used elsewhere or discarded. At the end of the sorting table, a Grape Crusher can be inserted to break the grape skins before the gapes fall into the Fermentation Tank. This is an 8-12 person operation.
There are three tables involved in managing data for the harvest and crush: Vessels, FermBatchDefinitions and HarvestActions
The Vessel table contains a description and specifications of each container used in winemaking and cellaring. Before a vessel can be referred to in another table, it has to be defined here. This screenshot shows, for example, the entry of a Mixing Tank. The following screenshot shows the listing of all vessels currently in use
:Before we record the harvest, we need to first create new records for the Fermentation Batches in the FermBatchDefinitions table defining the different fermentation batches to which the harvest will be allocated. This screenshot shows, for example, how we defined the batch 2017CLSR1
The HarvestActions table is used to record first the weight of bunches collected by 5-gallon bins for each row or vine, and the estimated percentage of weight left on the vine or dropped in the vineyard for each row. This screenshot shows how the weights were recorded by row for the 2018 harvest of the lower field:
Second, the HarvestActions table is used to record the sorting losses (bunch sorting, destemming, berry sorting, unused saignee from the vibration table) and how the net yield is allocated to the different fermentation tanks defined earlier. This screenshot shows the losses and allocations for the same harvest
This layout also summarises the grape quality as recorded in the berry tests, it provides an opportunity to record commentaries on the quality of each block and the harvest overall, and it shows the labour input (in total man-hours) accumulated to date for the must in each fermentation tank.
Tracking Results 2018
We scheduled three harvests in 2018:
On September 21 we harvested the Merlot and Cabernet Franc blocks in the upper field and mixed the berries into two small fermentation tanks, around 750 lbs.
On October 6 we harvested the Cabernet Sauvignon blocks in the lower field and put all together in the large fermentation tank, around 2,300 lbs.
On October 26 we harvested the last block, Petit Verdot, around 120 lbs.
Overall the quality and yields were excellent. We had some minor losses due to an invasion of wild turkeys which picked berries through the net. The following screenshots show the key data: