Flow measurement for the cold sterilisation of juices and sparkling beverages

One of Germany's largest manufacturers of mineral water and beverages produces juice-based softdrinks such as sparkling apple juice. The beverages are preserved on site to protect the end productsfrom things like bacteria, mould and yeast.

However, to avoid adversely affecting the taste and colour of the beverages, the company stays awayfrom traditional methods such as pasteurisation and hot filling, opting for a state-of-the-art coldsterilisation process.

The manufacturer uses a highly effective microbial control substance for the cold sterilisation. This food additive, known as dimethyl dicarbonate (DMDC), is added to the end product in extremely small doses to deactivate the enzyme (carboxymethylation). Within a few hours the ester breaks down into negligible amounts of methanol and CO₂. Both are found naturally in many fruit and vegetable juices. Cold sterilisationis thus considered safe and does not pose any health risks.

A dosing unit doses the DMDC. A dosing pump is used to introduce the medium into the main productflow, which is subsequently transported to bottling. In order to set the desired ratio of DMDC to beverage volume and to adhere to the approved limits, the flowrate of the sparkling juice must be continuously and precisely measured.

To accurately determine the volume flow of the fruit juice beverages the customer installed the OPTIMASS 1400 C Coriolis mass flowmeter. Due to the twin straight tube design featuring an optimised flow splitter there is virtually no pressure loss and the flowmeter is self-draining and easy to clean. For this reason it is the perfect choice for hygienic applications.

Upon customer request the measuring device was made of stainless steel (1.4404) and fitted withaseptic pipe screw connection (DIN 11864-1A) in DN 50. It has been installed in the standpipe,immediately before the ester is added using the dosing system. The converter on the Coriolis device is also made of stainless steel. In addition to information about volume flow, the device also provides the added up volume as well as a contact output when a minimum density is not reached.

Using the OPTIMASS 1400, the customer can add the DMDC according to a proportional control. The KROHNE device thus fulfills an important role in maximising yield. Based on the beverage flow, onlythe amount of sterilisation agent that is actually necessary to sterilise a maximum beverage volume is added. This makes it possible to effectively prevent expensive overdosing. Limits are observed. The mass flowmeter thus contributes to the production of a safe end product with a long shelf-life and the beverage producer can guarantee the best possible product quality by using this cold sterilisation process to protect the flavour.