Decanters for must production; future-proof thanks to innovative extraction technology

Brigitte Kirmeier
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Pressing is the process of making juice via crushing, and is derived from the Latin word calcatorium. The term has remained the same, but the methods have changed over time. Many wine pressing firms still work with the basic principle of pressing, fo

The conventional pressing principle with subsequent filtration usually entails problems that can be solved using decanter technology

Decanting centrifuges provide both high yields and high juice quality, as there is no filter layer as a barrier. The separation of the cell structures from the contents takes place solely based on the difference in density. This makes the decanter a modern universal machine combining the advantages of the other machines and eliminating their disadvantages: continuous process, short detention time, closed system, high space/time yield, high juice quality, low dead volume and no minimum batch size, high level of automation, and easy, automatic cleaning.

The decanter generates a gravitational field of about 3000g via its rotation. The mash is distributed into the rotor via an inlet chamber and is immediately accelerated so that the majority of the heavier solids concentrate on the drum wall, whilst the juice phase forms a layer towards the axis of rotation. To ensure that the juice and solids do not simply accumulate, but are continuously separated, the rotor has two outlets, one each for juice and solids. However, as the solids require additional forces to counteract the centrifugal acceleration and exit the machine, a screw conveyor rotates within the bowl at a specific differential speed. This conveys the heavy sediment towards the cone-shaped end of the machine where it is eventually ejected. The liquid level in the machine determines how dry the solid is – in other words the amount of the yield – in that the solid has to cover a specific drying path on the cone before it exits the rotor. This means that capillary liquid that is normally otherwise left over in filtration units is also extracted. The typical detention time in this process is significantly less than one minute, meaning there is barely any time for chemical and thus sensory changes to occur in the product.

The key factor is the method of removing the liquid phase from the decanter; any introduction of oxygen must be carefully avoided

The key factor for today's quality requirements is how the juice phase is "skimmed" out of the decanter. Versions with free overrun skimming can still sometimes be found. However, the clarified juice is delayed by the amount of energy and the presence of air (and therefore oxygen), and turbulence results in foam formation and oxidation, often preventing the use of these decanter types. This design also does not permit any change in the liquid level during operation, and this needs to be adapted in line with changing properties of the source product or other product flows. The approach in the HILLER DecaFood series is to remove the liquid phase from the rotor in such a way that there is no additional contact with air. This is made possible by HILLER's unique skimming system. This achieves the ideal sensory condition for every product. At the same time, this design variant allows the liquid level in the machine to be adjusted at any time at the touch of a button on the control, so that the yield is always optimal when operating conditions change. The suppression of the air intake is so effective that even an inductive flow meter reliably displays the current yield. This permits additional special automated mechanisms that were not previously feasible due to unreliable measured values. In addition, removing the juice under pressure means that no collection or buffer tanks and no transfer pump with complete piping and automation are required. The combination of these three features in one machine is unique, and is necessary to meet the challenges of the future. After all, in the face of today's competitive pressures nobody can afford to sacrifice yields or quality levels, or to make the process unnecessary complex.

The benefits of the Hiller DecaFood range are quite literally visible even once production has finished, as the combination of geometry, surface finish and degree of automation enables reliable, fast and fully automatic cleaning, meaning that ever-increasing hygiene standards are met at a low cost.

Both the cleaning and operating parameters are stored on the control in freely configurable recipes, meaning that frequent changes in product can be handled easily.

In order to take full advantage of the benefits of the decanter in the various applications, further process optimisation is sometimes necessary. For example, when using decanters the mash can be macerated more heavily, assuming there are no technical reasons preventing this. For this reason, HILLER has added a coordinated conditioner to the DecaFood series, and this unit can be used to the exploit this potential option quickly and easily. HILLER has also developed a preparation unit for clarification aids optimised especially for the requirements of grape mash processing. This is fully automatic and is optimally coordinated with the DecaFood system, ensuring exactly the right dose of optimally prepared solution. In addition, test facilities and experts are on hand to find the best individual solution every time together with customers and their consultants.Current examples illustrate the comprehensive benefits of HILLER's decanter technology:

In the field of wine production, HILLER has achieved a significant success in Spain and recently installed three decanters for a well-known wine producer. This success is of huge significance as the advance of decanter technology in Spain and throughout Europe is only just beginning.

Comparative trials in a Spanish winery have shown that HILLER DecaFood technology was not only the safest machine in operation, but also achieved by far the best wine quality (polyphenols, catechins, etc.). The crowning glory of these efforts is the sale of three large-scale machines to a renowned Spanish winery that from the forthcoming wine season will convert up to 75 tonnes of white grapes into must every hour there.

Tests at an Austrian refinery using various fruit varieties have shown that fruits such as apricots, plums and raspberries were extremely efficiently processed there using the decanter, whereas their conventional machine facilities either broke down or required considerable technical modification to run effectively. Using the DecaFood from HILLER, all the fruits were successfully processed, at least as well or better, i.e. with less effort (temperature, enzymes, filter aids, etc.), or a greater yield at the same quality level.

Whether it's direct juice from different fruit and vegetable varieties at over several hundred kg per hour or a highly efficient monoproduct plant with an hourly output of several tonnes, the HILLER DecaFood is a risk-free decision with a sustainable future.

Hiller Decanter for wine production
Hiller Decanter for wine production

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