Cleaning-in-Place (CIP) is a key process for maintaining hygiene and quality in the dairy industry. Proper implementation of this process prevents microbial contamination, product quality deterioration, and equipment damage. However, the hidden costs associated with resource consumption and environmental consequences of CIP have drawn increasing attention. This section explores three core aspects for a better understanding of CIP: general principles, resource consumption, and environmental considerations.
Introduction and General Considerations in CIP Cleaning
Fouling and deposits inside dairy processing equipment—especially the internal surfaces of machines and pipelines—pose one of the industry’s main challenges. These issues vary depending on process parameters such as temperature, pH, and time. For instance, deposits on heat exchanger surfaces are classified into two types, each with a different composition of fat, protein, and minerals. These fouling issues cause multiple problems including reduced food safety, lower equipment efficiency, product quality loss, increased energy use, pressure drops, product waste, and higher environmental loads in wastewater. Moreover, biofilm accumulation can increase microbial loads and reduce product shelf life, further highlighting the importance of hygienic cleaning processes.
CIP is a widely used and effective industrial sanitation method, where cleaning fluids circulate through equipment and pipelines without dismantling the system. The CIP process typically includes five stages, using alkaline, acidic, and—if needed—disinfectant solutions. While this system is extensively applied in the dairy and broader food industry, it consumes vast amounts of water (e.g., producing 1 kg of cheese may require up to 5000 liters of water), with CIP accounting for the majority of this usage.
Various chemicals are used in CIP, among which chlorinated compounds (like sodium hypochlorite) are under scrutiny. Although active chlorine is a powerful antimicrobial agent, it is quickly neutralized by dairy components such as lactoglobulin, lactalbumin, casein, and fats, requiring higher dosages. Furthermore, chlorine use can lead to the formation of harmful by-products like chlorates, which pose health risks—especially for infants. As a result, there’s a growing trend toward reducing the use of chlorinated disinfectants.Safer alternatives like peracetic acid and hydrogen peroxide have gained traction. These effective antimicrobials are biodegradable and eco-friendly, producing only water, oxygen, and acetic acid as by-products. However, acetic acid may increase the biological pollution load in wastewater and, in high concentrations, be toxic to humans and the environment.
Choosing the right CIP method requires evaluating multiple factors such as chemical type and quantity, water consumption, disposal methods, and associated costs. Most conventional cleaning agents are not biodegradable and must be neutralized before disposal. Additionally, inadequate disinfectant dosages can contribute to antimicrobial resistance in bacteria—an important food safety concern.
On an industrial scale, the use of energy, water, and cleaning chemicals are the main contributors to the dairy sector’s environmental footprint. Lifecycle assessments of organic mozzarella cheese production show that cleaning agents, particularly alkaline ones, contribute significantly to environmental burden. This has led to interest in enzymatic alternatives to conventional CIP chemicals, which can reduce pollution and prevent equipment corrosion. Besides being major contamination sources, biofilms also contribute to corrosion, reduced heat transfer, and increased flow resistance in dairy systems. Even after cleaning, biofilms may regenerate on surfaces, requiring thorough cleaning after each production cycle. Although CIP is the most common method for removing deposits and biofilms, its effectiveness varies, and biofilms often exhibit resistance to chemical and physical cleaning. The use of enzymes in combination with biocides has emerged as an effective and promising solution for biofilm control in the dairy industry.
This article provides a comprehensive review of CIP methods in dairy production, highlighting issues with chemical-based approaches (e.g., high water and energy use, environmental concerns, inefficiency in removing biofilms), and their impact on sustainability. It also explores novel strategies, such as enzymatic cleaning, either as a replacement for or supplement to chemicals—particularly in cheese manufacturing—to offer new insights for improving the sustainability and efficiency of CIP systems.
Water and Energy Consumption in Dairy CIP Processes
CIP processes in the dairy industry consume significant energy, mostly due to the large volumes of hot water required. While lowering the temperature may seem like a solution, studies have shown that reducing the cleaning solution temperature from 65–80°C to 50°C—even with 1% caustic soda—can cause CIP failure in about 4.2% of cases (roughly 15 failures per year).
- Energy Consumption During CIP
Energy audits in dairy facilities across several European countries reveal that CIP—especially in evaporators and dryers—accounts for a significant portion of operating costs (10–26% of total energy use). In an Australian facility producing cheese, whey powder, and WPC, CIP ranked third in energy consumption after spray drying and evaporation (9% of total energy). In UK dairy plants, about 80% of energy is used to produce hot water and steam for processes like pasteurization, evaporation, drying, and CIP.
Natural gas is typically the main heat source, while electricity powers pumps, storage systems, separation processes, and cleaning systems. CIP electricity usage is comparable to pasteurization. Lifecycle assessments of cheese production in Wisconsin, USA, have also identified pasteurization and CIP as the most energy-intensive steps—contributing to environmental impacts such as global warming.
Reducing CIP-related energy consumption not only cuts costs but also improves overall plant energy efficiency and reduces damage to equipment caused by high temperatures and corrosive conditions.
- Water Consumption During CIP
Water use is a major environmental concern in dairy processing. The food industry ranks third in water consumption and wastewater generation, following chemical and petroleum refining sectors. In dairy plants, the majority of water is used in CIP rather than as a product ingredient.
Globally, processing 1 liter of milk requires between 0.2 and 11 liters of water, with CIP accounting for approximately 28% of that. The highest water consumption is in cleaning evaporators and dryers, followed by silos and feed lines (310–225 and 388–105 liters per ton of milk, respectively). According to Dairy Australia, CIP uses 28% of total water, followed by pasteurization at 25%.
Importantly, steam condensate water from pasteurization can sometimes be reused, but CIP water is usually discharged. Thus, CIP is a primary driver of water use in dairy operations.
Water plays several roles in dairy plants: heat transfer, cleaning, and transporting nutrients like fats, proteins, and sugars. Given the demand, wastewater management is a major cost factor. However, not all water is externally sourced—some comes from milk itself or is recovered from evaporator condensate. To ease wastewater treatment burdens, CIP water use must be reduced, cleaning solutions should be recycled, and condensate loss minimized.
Strategies for Reducing Water and Energy Use in CIP
Recent trends in the dairy industry have focused on minimizing CIP-related water and energy use. Approaches include using alternative cleaning agents, optimizing water and energy consumption during CIP, and recovering chemicals through membrane technology. Reusing water from milk evaporation is also a viable option—some New Zealand plants have shown that condensate alone can meet CIP water demands.
Using this water requires membrane filtration systems, which must also be cost-effective. Another strategy is to use steam boiler condensate or reverse osmosis (RO) permeate from whey protein processing. One study showed that combining RO and ultrafiltration can recover up to 47% of water in whey. This water, after microbiological and chemical testing, was deemed safe for CIP and may even protect equipment from hard water damage.
Enzymatic cleaning solutions offer another path to reducing water and energy use, as they require less water for cleaning and rinsing. Their use in the textile industry shows promise for reducing chemical, water, and energy demands in dairy CIP. Enzymes work at mild temperatures and pH, requiring less energy, lowering wastewater treatment costs, and avoiding equipment damage due to non-corrosive properties.
Environmental Considerations of CIP in Dairy Plants
The typical five-stage CIP process in dairy plants uses alkaline and acidic cleaning agents. These chemicals are costly and must be neutralized before disposal, adding to both financial and environmental burdens.
- Salt Load
During the alkaline cleaning stage, 0.5–1.5% caustic soda (NaOH) or similar agents are circulated at 70–80°C with high flow rates. In Germany, CIP-related salt loads in wastewater are estimated at 2,000–6,000 tons per year. These salts, left after neutralization, are non-biodegradable and pose serious environmental risks such as soil salinization and groundwater contamination.
- Nutrient Load and Eutrophication Risk
Chemicals used in CIP—such as nitric acid, phosphoric acid, nitrogen, and phosphorus from detergents and surfactants—increase the biological oxygen demand (BOD) of dairy wastewater. This contributes to eutrophication (nutrient overload in water), promoting algal blooms and harming aquatic life. Environmental assessments show that CIP agents account for up to 80% of eutrophication potential in dairy effluents. Reducing or replacing these chemicals is key to mitigating this issue.
- Health Hazards from CIP Chemicals
Sodium hypochlorite (NaClO), a common CIP disinfectant with strong microbicidal properties, can form chlorinated organic compounds upon contact with milk constituents like acetoin and diacetyl. Some of these, such as trichloromethane (TCM or chloroform), are Group 2B carcinogens. If not fully removed after cleaning, these residues can accumulate in production lines and transfer to high-fat products like cheese and butter, posing safety risks and causing off-flavors. Hence, chlorine-based compounds must be strictly controlled, and their presence in final dairy products carefully monitored.
Conclusion
Although CIP is essential for producing safe, high-quality dairy products, it faces challenges such as high energy and water consumption, formation of harmful by-products, and significant environmental burdens. In Part Two of this article, we will explore innovative solutions like enzymatic CIP and its applications in biofilm control and cheese production.
Reference:
Pant, Karan J et al. “Towards sustainable Cleaning-in-Place (CIP) in dairy processing: Exploring enzyme-based approaches to cleaning in the Cheese industry.” Comprehensive reviews in food science and food safety vol. 22,5 (2023): 3602-3619. doi:10.1111/1541-4337.13206
