A producer of sausages and canned meat in Germany operated 13 full water autoclaves (Rotomats). The autoclaves were connected to an open evaporative cooling system to re-use the spent cooling water after each batch. The cooling water is treated with chlorine dioxide for microbiological control. The water is changed every second weekend to reduce spot formation on the cans.
Since 2005 the use of metal-ions such as zinc or molybdate as corrosion inhibitors for water treatment was prohibited by local authorities. To protect cans and steriliser equipment from scaling and corrosion, an inhibitor based on phosphonate and amines was used. The cans, however, showed frequent corrosion and deposits after the sterilization. Therefore, manual cleaning was required and customer complaints about corroded cans needed to be addressed.
A thorough survey of the sterilizers and the cooling system was performed by Veolia. Based on the results, one of the new developed Mo-free corrosion inhibitors from the FoodPro* ST range was selected to run a field trial at one of the Rotomats.
Since the Rotomat was still connected to the cooling system, the cooling water was treated with a competitor’s product. Switching to FoodPro ST showed great improvement in the appearance of the cans. Due to these good results it was decided to run a full scale trial on all the Rotomats and the cooling system.
After a complete change of the process and cooling water, FoodPro ST8070 was introduced as a scale and corrosion inhibitor and dosed to all Rotomats. The cans were free of corrosion, even in the score of ring-pull lids, as well as the crevice between lids and can body. Brightness and cleanliness were much improved, so that manual post-sterilization cleaning was no longer necessary.
Thus, the cleanliness of the cooling water was able to be maintained longer, resulting in an extension for a full exchange of the cooling water to 4 weeks.