Reducing Caustic and Improving Performance in Clean-in-Place Formulas
Clean-in-place (CIP) is a method for cleaning equipment, process lines, and vessels commonly used in food, beverage, pharmaceutical processing and other industries that need frequent internal cleaning of their systems and equipment. CIP systems help maintain a hygienic process environment to ensure product purity and quality without removing or disassembling equipment or piping during the cleaning process. Clean-in-place works by pumping cleaning, rinsing, and sanitizing solutions through the same piping path that contains the manufactured good in order to remove product soil from internal surfaces.The primary challenge with clean-in-place is balancing effective cleaning (using a very low or no foam detergent) with the need to protect the equipment and pipelines from corrosion and deterioration. There has been growing interest in reducing the temperature of cleaning and minimizing the amount of corrosive or hazardous chemistries (such as acid or alkali) used in typical, CIP applications. For every 1°C reduction in CIP temperature there will be a 1/60th reduction in the energy needed to heat the fluid. Plants are also looking to reduce the number of United States Pharmacopeia’s (USP) Global Health Monographs required on the products they use, as dictated by the Global Health Standards (GHS) Program. Fewer hazard labels signal a safer and more desirable product for end-users when cleaning performance is equivocal.The typical CIP process is an involved one. It requires a pre-cleaning step that removes soils and heats the piping, followed by cleaning with a detergent, a rinse step, an acid rinse, another water rinse, and finally, a bleach or biocide rinse.BASF worked to create a CIP cleaner that not only outperforms industry benchmarks in terms of eliminating food soil, producing low foam levels, and cleaning at lower temperatures, but one that does so without bleach and with less caustic material. The goal was to create a high-performing bleach-free end formula that does not corrode soft metal, such as aluminum and copper, and requires fewer Global Health Monographs from GHS.
Alkaline CIP Formula
We started by developing two high-alkaline, chlorine bleach-free, formulas. The BASF formula with reduced caustic of 12.25% (formulation 35074-139-1) provided cleaning on par with 20% caustic (formulation 35765-28-1). In formulation 35074-139-1, we used a surfactant (Plurafac® CS-10) to help reduce the amount of caustic, resulting in an even less corrosive end formula. The cleaning performance of these two formulations on milk soil was superior to a commercial (chlorine-free) detergent and various caustic solutions. All formulations were tested at 1:200 dilution ratios and moderate temperature conditions of 45°C, when traditionally, milk is cleaned at 60°C.
On milk scale, at a cleaning temperature of 45C, the commercial product only cleaned 60% of the milk scale. The formulation with 50% and 100% caustic diluted at 1:200 cleaned 65% and 70% of the scale, respectively; both BASF formulations removed close to 90% of the milk scale.
Alkaline CIP Formula Corrosion on Aluminum
An ideal CIP cleaner will not corrode the metal that makes up the pipes and tanks or the rubber gaskets and seals within a system. A test for corrosion on Aluminum alloy (Al-5052) was conducted and extrapolated by examining as millimeters (mm) of metal corroded over a period of one year. The commercial benchmark showed no corrosion, but it also delivered a cleaning level of only 60%. A formula with 50% NaOH corroded at a rate of 0.2 mm per year, while a pure sodium hydroxide (100% NaOH) formula lost 1 mm of aluminum per year. BASF Formula 35074-139-1 had the second lowest corrosion (after the commercial product) but still delivered superior cleaning at close to 90%, with less caustic.
Alkaline CIP Formula Corrosion on Rubber
When tested on ethylene propylene diene terpolymer (EPDM) and Viton (a brand of fluorocarbon-based synthetic rubber), Formulation 35074-139-1, with the lowest level of caustic, showed the least corrosion on both material types. Formulation 35765-28-1, with a higher level of caustic, showed more corrosion than the benchmark on EPDM, but no corrosion on Viton.
Moderate pH CIP Formula
There is a trend in the industry to reduce hazardous and corrosive ingredients from formulations, while maintaining performance. With that goal in mind, we developed a moderate pH, or close to neutral, set of CIP formulations. In Formulation 35765-33-1 and Formulation 35765-14-1, we used an enzyme (Lavergy™ Pro 104 LS) to boost cleaning performance without adding caustic or corrosive materials.To better understand the contribution of the added enzyme, an ingredient that will only survive in a moderate pH system, we created a formula without the addition of Lavergy™ Pro 104 LS. Formulation 35765-12-2 is a low pH formula that does not have the additional enzyme. We also provided options for super concentrates (in formulation 35765-33-1). While products are typically tested at 1:200 dilution, this formulation can be tested at 1:1800 dilution.
Moderate pH CIP Formula Performance
We tested each formula with the same level of raw material at-use. The super concentrated, moderate pH Formula, 35765-33-1, cleaned close to 90% of the milk scale at 45C, while Formula 35765-14-1, with just 1% Lavergy™ Pro 104 LS, still outperformed the benchmark. Without the Lavergy (Formula 35765-12-2), performance dropped to 60%.
Moderate pH CIP Formula Corrosion on Aluminum
None of the moderate pH formulas, including the two with Lavergy Pro 104 LS, resulted in any significant corrosion on aluminum. The picture of the aluminum plates shows the performance comparison to other high alkaline detergents. Keeping the pH moderate helps with corrosion. The underlying benefit is that the Lavergy Pro boosts the cleaning performance while keeping the pH moderate.
Moderate pH CIP Formula Corrosion on Aluminum
Exposure to the moderate pH formulas did not cause corrosion on either EPDM or Viton.
Moderate pH CIP Formula Enzyme Stability
The enzyme in both Formulation 35765-33-1 and Formulation 35765-14-1 remained stable during the accelerated long-term stability testing that was performed on the formulations.
Food and beverage processing plants are looking for clean-in-place formulas that are highly effective, but use less caustic, and work well at lower temperatures. Using unique ingredients and a creative approach, it is possible to develop new solutions that boost cleaning and reduce corrosion, saving plants time, energy, and money while maintaining superior performance.