Bridging Environmental Monitoring Program Results with Sanitation Practices

Organic soils (carbohydrates, fats, oils, proteins) require different methodologies for cleaning. For best results, all matrices should be identified prior to chemical selection and cleaning dynamics to SOP development.

• Carbohydrates. Some carbohydrates, such as sugars, may only require water for removal, while others, such as starch, may need a detergent. A cold water pre-rinse is best for starchy soils because a hot rinse can cause the soil to stick to the surface, making it difficult to remove.
• Oils and fats. Oils and fats may necessitate the additional chemical reactions of saponification or emulsification for removal. Saponification, conversion of fat/oils to soap and alcohol, occurs by the addition of alkaline (caustic) and hot water. Emulsification is the suspension of a typically immiscible liquid in another liquid. The process breaks down the surface tension of fat/oils, allowing for mixing of water. Once suspended, the fats/oils are further broken into small fat globules, allowing more mixing into water and permitting easier elimination through rinsing.
• Proteins. Proteins are generally the most difficult soils to remove. Routine cleaning of protein processing equipment is best achieved through the addition of chlorine to an alkaline solution. The chlorine peptizes (breaks down) proteins into smaller amino acids, facilitating removal from the system. Although effective, it is not recommended in all applications, such as RO membrane systems or evaporators. Additionally, when proteins are heated, they unfold (denature) and will adhere to a surface. In this state, they can be difficult to remove. Cold residues are easier to purge.

Once the pH, mineral content, and organic content of the soils are identified, the chemistry of the cleaning detergents may be determined and the best-fit product selected. In choosing the chemistry, compatibility with surfaces must be considered. While soil identification might lead to a strong acid product, the equipment may not be compatible with that selection, although some products may have choices within their lineups (e.g., soft metal safe).

Cleaning Dynamics

Once detergents are chosen, the procedures for their use will depend on three additional components: application time, water temperature, and mechanical action. Together, the four components are cleaning dynamics devised by Herbert Sinner in the 1950s and dubbed the “Sinner’s Circle” (See Figure 1). A balanced cleaning process requires a percentage of the components totaling 100 percent. If one component is changed, the others must increase or decrease to balance.

Product labels indicate typical time, temperature, and concentrations, but adjustments may be needed for time constraints or lack of available mechanical action (Figure 2). Increased CIP turbulent action increases solubility of most materials, rendering them easier to remove. Generally, the temperature range of cleaning is between 90°F and 185°F. Temperatures above 185°F may induce reactions that bind proteins more tightly to a surface, and in those below 90°F, (butter) fat remains a solid. If cleaning fats, the minimum effective cleaning temperature is 5°F higher than the fat melting point. A general rule of thumb is that cleaning temperatures should be 5°F to 10°F higher than the processing temperatures.

Mechanical action will be dependent on the type of action performed. Hand or manual cleaning may require an extended time period to ensure the removal of all matrices. CIP fluid flow applies the force or turbulence as the mechanical action. A fluid velocity of five feet/second for 1.5- to 2.5-inch pipes gives the minimum result for effective cleaning. For three-inch lines or larger, eight feet/second is recommended. This velocity results in the amount of flow necessary to achieve turbulent flow instead of laminar flow in pipes.

Time is a valuable cleaning process resource. Limiting the time needed for cleaning will only lead to later implications, such as ineffective sanitizer action, because without removal of soils, the sanitizer will not reach the microbial cell surface, causing its destruction.