How to maximise grape yield during wine production

Winemaking is a multifaceted process with variables in each step. Grape pressing is one of the more important tasks: how and when it’s done can affect the flavour of the finished product, and also can play a key role in producing a higher yield. Winery managers know that efficiency during grape pressing helps increase production and ultimately boosts profitability.

From vine to wine: the crushing saga of a grape

After the initial crushing, pressing and de-sludging are complete, the remaining residue of skin and seeds is called the ‘grape marc’ or ‘grape pomace’. Vintners have discovered that sometimes enough moisture remains in the grape marc to warrant another pressing, resulting in additional useable liquid from that particular batch. To determine if it’s worth the effort, they can verify the moisture content in a sample of the grape marc.

A toast to efficiency

Moisture analysers provide a rapid alternative to the time-consuming task of oven testing. The PMB from Adam Equipment speeds up the drying process and eliminates the possibility of burning a sample and getting false results.

The PMB features a single circular 400 W energy-efficient halogen bulb, which heats the specimen in 1°C selectable increments. A large, circular heating chamber is designed to heat samples evenly. Three heating options provide the flexibility to customise temperatures and test methods. The standard setting heats to one temperature in one step. For the ramp setting, the user chooses a temperature and sets the amount of time for the heat to reach that temperature. The step setting lets the user program up to three temperatures and times at each temperature.

For wine production control, the process is simple. Evenly spread approximately 20 g of the grape marc on the aluminium sample pan and run the sample at 100°C on the single heat setting. Temperature in the weighing chamber is monitored by a sensor. As the temperature approaches the final value, the heating bulb cycles on and off to maintain the designated temperature. Drying takes between 30 and 120 min, depending on the amount of residual moisture in the grape marc.

The initial temperature increase happens quickly, taking about a minute to reach 90% of the final temperature, and then another 30 seconds to reach the final figure. This method keeps the temperature from rising above the set point, eliminating possible damage to the sample. To monitor progress, PMB provides current results at set intervals.

Varietal versions of the PMB

Adam offers three models — PMB 53 features a capacity of 50 g and readability of 0.01%/0.001 g; PMB 163 features a capacity of 160 g and readability of 0.01%/0.001 g; and PMB 202 features a capacity of 200 g and readability of 0.05%/0.01 g.

Connecting with other devices is simple, as the PMB offers both a USB port and RS-232 interface. Users can log or print information, communicate with computers or transmit test programs and results. There is no need for additional software to take readings, giving users freedom to collect data in any location. The internal memory stores up to 99 test results; extra results can be saved to a flash drive or computer to quickly verify and compare readings.

The PMB retains and stores set-up information, saving the time and effort of having to re-enter the information in the next analysis. An ergonomic design features handles on both sides for ready access, and a pan lifter is provided for placing and changing samples.

Image credit: ©stock.adobe.com/au/magdal3na

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