Application of CIP systems in food production.
At present, clean-in-place (CIP) systems have been widely used in food production enterprises with a high degree of mechanization, such as beverage, dairy, juice, and alcoholic beverage industries. CIP, also known as cleaning-in-place or in-place cleaning, refers to a method of cleaning the contact surfaces of equipment without disassembling or moving the equipment, using high-temperature, high-concentration cleaning solutions with strong action to clean the surfaces that come into contact with food.
At present, CIP is widely used in the food industry, with the following main characteristics: it can ensure a certain cleaning effect and improve product safety; save operation time and improve efficiency; save labor and ensure operational safety; save energy such as water and steam, and reduce detergent usage; enable large-scale production equipment with high automation levels; and extend the service life of production equipment.
Mechanism of CIP cleaning action
Chemical energy is mainly generated by the chemical reagents added, and it is the most important factor determining the cleaning effect. Generally, manufacturers can choose detergents based on the nature and degree of contamination of the object being cleaned, material composition, water quality, selected cleaning method, cost, and safety. Commonly used detergents include acid and alkali detergents and sterilizing detergents.
The advantages of acid and alkali detergents are: they can kill all microorganisms; they have a good effect on removing organic matter. The disadvantages are: they have strong irritation to the skin; they are difficult to rinse off with water.
The advantages of sterilizing agents are: rapid sterilization effect, effective against all microorganisms; generally non-toxic after dilution; not affected by water hardness; form a film on the equipment surface; easy to measure concentration; easy to meter; can remove malodors. The disadvantages are: they have a peculiar smell; require certain storage conditions; sterilization effects vary greatly at different concentrations; easily freeze at low temperatures; improper use may cause side effects; contamination by dirt significantly reduces sterilization effect; spilling can stain the environment and leave marks.
In acid and alkali detergents, the acid refers to a 1%–2% nitric acid solution, and the alkali refers to a 1%–3% sodium hydroxide solution used at 65°C–80°C. The sterilizing agent is a commonly used chlorine-based disinfectant, such as sodium hypochlorite.
Thermal energy: At a certain flow rate, the higher the temperature, the lower the viscosity coefficient and the larger the Reynolds number (Re). An increase in temperature can generally change the physical state of the dirt, accelerate the chemical reaction rate, and increase the solubility of the dirt, facilitating the removal of impurities during cleaning, thereby improving the cleaning effect and shortening the cleaning time.
Kinetic energy: The magnitude of kinetic energy is measured by Re. The general standards for Re are: for thin liquid flowing down from the wall surface, tank type Re > 200, pipe type Re > 3000, and Re > 30000 gives the best effect.
Solvent action of water: Water is a polar compound and has almost no dissolving effect on greasy dirt, has a certain dissolving effect on carbohydrates, proteins, and lower fatty acids, and has a strong dissolving effect on electrolytes and organic or inorganic salts.
Mechanical action: Action generated by movement, such as the pressure and friction produced by stirring and spray cleaning.
Factors affecting cleaning effectiveness
Degree of equipment contamination, nature of contaminants, and product production process: These are important reasons determining the cleaning effect. If CIP conditions are not determined based on these characteristics during cleaning, it is difficult to achieve the ideal goal or may lead to excessive cleaning costs.
Types of cleaning agents: At present, there are many types of cleaning agents used in the food industry, mainly acids and alkalis, among which sodium hydroxide and nitric acid are the most widely used. Alkaline detergents have a good removal effect on dirt with high protein content, but they have a certain corrosive effect on food rubber gaskets, etc. Acidic detergents have a good effect on stubborn dirt that alkaline cleaning agents cannot remove, but they are corrosive to metals to a certain extent, so some anti-corrosion agents should be added or they should be rinsed thoroughly with clean water. Other cleaning agents include surfactants and chelating agents, but they are only used when there is a special need, such as using chelating agents to remove metal ions when the cleaning water has high hardness.
Concentration of cleaning agents: When increasing the cleaning agent concentration, the cleaning time can be appropriately shortened or the lack of cleaning temperature can be compensated for. However, increasing the concentration will lead to higher cleaning costs, and a higher concentration does not necessarily effectively improve the cleaning effect. Therefore, manufacturers should determine the appropriate concentration based on actual conditions.
Cleaning temperature: Generally speaking, for every 10°C increase in temperature, the chemical reaction rate increases by 1.5–2.0 times, and the cleaning speed also increases correspondingly, resulting in a better cleaning effect. The cleaning temperature is generally not less than 60°C.
Cleaning time: Cleaning time is affected by many factors, such as cleaning agent type, concentration, cleaning temperature, product characteristics, production pipeline layout, and equipment design. The cleaning time must be appropriate; too short a time cannot effectively remove the dirt, while too long a time wastes resources. Taking the beverage industry as an example, the cleaning procedure is as follows:
1. Rinse for 3–5 minutes with hot water at room temperature or above 60°C; alkali wash for 10–20 minutes with 1%–2% solution at 60°C–80°C; intermediate rinse for 5–10 minutes with clean water below 60°C; final rinse for 3–5 minutes with clean water.
2. Rinse for 3–5 minutes with hot water at room temperature or above 60°C; alkali wash for 5–10 minutes with 1%–2% solution at 60°C–80°C; intermediate rinse for 5–10 minutes with clean water below 60°C; sterilization for 10–20 minutes with hot water above 90°C.
Cleaning flow rate: Ensuring the flow rate actually ensures the flow velocity of the cleaning liquid during cleaning, thereby generating a certain mechanical action, that is, increasing the impact force by improving the turbulence of the fluid to achieve a certain cleaning effect.
Evaluation criteria for CIP cleaning effectiveness
As an ideal CIP for the food industry, the cleaning effect must meet the following standards:
Sensory
Odor: Fresh, with no peculiar or off-odors. For special treatment processes or special stages, slight odors may be allowed but must not affect the safety and quality of the final product.
Visual: The cleaned surface is bright, with no standing water, no film, no dirt, or other residues. At the same time, after CIP treatment, the equipment's production and processing capacity should show significant improvement.
Hygiene indicators: Microbiological indicators must meet relevant requirements; the treatment must not cause an increase in other hygiene indicators of the product.
Economy: Under the condition that cleaning requirements are simultaneously met, cost is an important factor in measuring cleaning effectiveness.
Operation: CIP operation must be relatively safe, convenient, etc.
With the continuous improvement of mechanization and automation in food production, CIP systems have been widely studied and applied. At the same time, with scientific progress and the continuous standardization of the market, their penetration rate in food production will continue to increase.
Jiangsu Qiyoulong Intelligent Equipment Co., Ltd., beer packaging production lines, beer production lines, bottle washers, filler-cappers, pasteurizers, case packers, decasers, depalletizers and palletizers, case washers, bottle conveying systems, pressureless conveying systems, case conveying systems.