It is well known in the dairy industry that hot milk curds, such as used in the production of pastafilata cheese, tend to stick to metal surfaces, even if highly polished. On the one hand, this sticking gives rise to obvious problems in the operation of cheesemaking equipment such as kneading and molding machines, particularly with respect to conveying augers and molds; on the other hand, the adhering curds make it difficult and time-consuming to clean the machine at the end of the day. Consequently, all parts of machines and production lines for pastafilata cheese which are to contact the hot cheese (such as walls of hoppers and vats, conveying augers, mixing equipment, etc.) are currently coated with an anti-stick paint, which as a rule is polytetrafluoroethylene (PTFE, such as the material commercially known as Teflon) or other similar product. Until now, the polytetrafluoroethylene coating has been the only known and effective approach to prevent the sticky adhesion of hot curds to machine parts. Moreover, a coating of PTFE or other similar compound is also used, outside the dairy industry, as an anti-stick treatment in pots and saucepans.
However, non-stick coatings in food equipment, particularly cheesemaking machines, have several drawbacks and limitations. Firstly, the coat will progressively deteriorate, sometimes quite rapidly, whenever the deterioration is triggered by an initial damage, such as scoring of the coat, as this will give rise to material peeling. In such cases, which involve the shutdown of the operation, the machine has to be disassembled and the parts have to be re-coated. The expense for such periodic maintenance, including actual disbursements and machine shutdown, is considerable, because the parts must be dismantled and re-coated by a third party, with waiting times of up to 30 days.
Even for original manufacturers of food industry equipment, the necessity to coat the equipment with Teflon involves additional costs and manufacturing delays, because, as a rule, the non-stick coating operation is outsourced to specialized firms.
Last but not least, PTFE, although chemically inert and generally regarded as non-toxic at temperatures below 200° Celsius, and therefore considered harmless for the health of the consumers, has recently given rise to doubts concerning its toxicity and its compatibility with food, and suspicions have even been put forward that it may be carcinogenic: both the U.S. Environmental Protection Agency and several consumer associations in different countries are conducting investigations to assess the degree of toxicity of PTFE and its possible danger to human health.
USPTO Backgrounds
USPTO Backgrounds