The Winemaker's Art Receiving the white grapes - Part I

After a hard year of taking care of the vines, the grapes are ready to be crushed. In the winery everything must be in order and perfectly cleaned for the sake of avoiding any problems during the winemaking process. Today we are going to see how we prepare the day before crushing the whites or just before the crush. Unfortunately I have no material for mechanically harvesting the white grapes so I will show you what we do when we receive crates full of grapes harvested by hand.

Just to give you an idea. We are in a beautiful village of southern France on an altitude of 500m above sea level. This means that grapes here ripen later than the grapes from the nearby region. This is a pneumatic press which means that in contains a membrane made by reinforced polyurethane-clad fabric.

This kind of press is excellent to make quality white wines. We always start by plugging all kind of equipment we are going to use to check if they are working properly. The plug of this press is a 32 Ampere plug. It's a bigger plug than those of our pumps the destemmer/crusher's and the lift conveyor's plugs are 16 Ampere.

I remind you that the strength of an electric current in amperes is how fast an electric charge will move from one place to another. Which means how many electrons will pass from an electric circuit per second. Generally most of the machinery used in winemaking use a three-phase electric current which means 3 cables plus 2 cables more the neutral cable to close the circuit and the grounding cable. This is our lift conveyor which we put up to these pallets with a forklift so that grapes can reach the press's doors.

We will also put the destemmer on the pallets in case we don't want whole-bunch grapes in the press. As you see theory and practice are 2 different things. This is where the stems will be placed. We can see that the screw feed of the destemmer sends the grapes to be destemmed.

The sifter (basket, cage) and the shafts move in opposite direction and as a result the grapes can be separated easily. We can also adjust their speed. Both of the red buttons stop the function of the machine. The big one is the emergency STOP button and the black button starts the machine.

We need to set up our line from the press to the tank. The size of the press's outlet is of a circumference of 60cm so I will put a 50cm reducer in order to connect my 50cm valve here. I will explain to you later why a valve is convenient in this case. If I am too tired, I prefer not to use a spanner to connect the parts.

A sightglass is very useful also because it lets us see through the colour of the grape juice that goes into the tank and see if there is air passing inside. I tighten it up. Now I can connect my 50cm hose. I turn on the press which needs some time to get ready.

You need to read the manual in order to operate a press you have never operated before. There are presses more or less user-friendly. However, the principle of all pneumatic presses is simple it presses by inflating the membrane of the press with air. It deflates it's turning and then the same thing over again.

Now I am opening the doors and I turn the press so that any water remains from cleaning get out. This is the reason why I hadn't connected the hose with the press when I was setting up my line. This is a modern press so its doors open and close automatically by pressing some buttons. In order for the doors to move they need to be exactly on top of the press.

So I put the press in a position where I can fill it up with the grapes. I also put the conveyor lift in place. I don't forget to release the breaks. I lower it manually with the lever.

Now all grapes will get in the press. Another extremely important thing is to have already disinfected the wine tanks to be used. Taking into consideration that the tank is totally clean I need to rinse it well and check if there is something forgotten inside just in case. Rinse thoroughly to be sure.

I must not forget to rinse the valves the lid and the liquid level gauge. We are going to connect a 50cm hose in my wine tank and my pump. That's something very useful but expensive. It's dry ice.

Dry ice is pressurized CO2 in a solid phase of which the temperature is naturally at -78,5C. It has a double function. While it is subliming CO2 gas is being freed. CO2 is heavier than oxygen so it takes the place of oxygen in the lower layers of air.

It also makes must's temperature descend rapidly. I put dry ice in the tank before I fill it so that the juice doesn't get oxydated during the first seconds of the transfer when the juice splashes in the tank from pump's power. Now that I'm done setting up the lines I tighten everything and I open the valves of the tank and the press. Francois just arrived with the first load to be weighed.

I need to weigh every pair of tires with the tractor firstly with the load and afterwards empty so I can find the net weight. Great! How many crates you have in there? It's of vital importance for me to know firstly what is the exact quantity of grapes arriving so to keep record of what I have and calculate my theoretical must production and secondly to calculate the quantities of sulphates and other oenological products I will add. So the load is here! Come on! This way! You are doing great! Stop!.