“Process Hygiene in the Food Industry: The Role of Chemical Activity in CIP Systems”
Table of Content
Industrial Hygiene Standards: The Clean-In-Place (CIP) System
Compliance with current industrial hygiene standards is a cornerstone of the modern food industry. In this context, the production process must adhere to strict cleaning and sanitization procedures to ensure the quality and safety of the finished product—characteristics that are of primary importance to the consumer.
In modern food industry plants, equipment that handles products and various process intermediates is subjected to automated cleaning operations using so-called clean-in-place (CIP) systems.
CIP systems, initially developed in the dairy sector to meet the need for rapid and frequent cleaning operations, have gradually been adopted across all areas of the food industry and in other sectors where process hygiene is crucial, such as the pharmaceutical industry.
During clean-in-place operations, various substances are circulated through the internal surfaces of equipment in contact with the product—particularly pipelines, valves, and pumps—following well-defined procedures. The cleaning of equipment is achieved through the physical action (a combination of thermal and mechanical effects) of the fluid in contact with the surfaces, as well as the chemical action of the detergents present in solution.
A complete CIP system typically consists of the following components:
- Pipelines for the distribution and recovery of detergents,
- Tanks for storing cleaning solutions,
- Heat exchangers,
- Spray heads,
- Flow management devices (pumps, valves, sensors, meters, etc.),
- PLCs (programmable logic controllers) and auxiliary systems.
Mechanical Energy and Chemical Activity in Automated Cleaning
Whether manual or automated, cleaning of the plant always involves the combined action and control of four key factors: fluid velocity, detergent concentration, fluid temperature, and phase duration. In manual cleaning operations, mechanical action—achieved through scraping and scrubbing surfaces—plays a central role.
In automated CIP systems, however, the mechanical energy provided by the impact of liquids on tank surfaces or the turbulent flow of liquids in pipelines is not sufficient to ensure effective cleaning of equipment. To compensate for insufficient mechanical action, clean-in-place operations rely on the other key factors mentioned, particularly the chemical activity of the substances in solution.
In the food industry, the chemical treatment of residues within equipment varies depending on the nature of the residues and is influenced by many variables, such as:
- temperature,
- contact time,
- the pH of the cleaning solution,
- the quality of the water used as a solvent.
To achieve effective cleaning, it is essential to understand the nature of the residues to be removed and how they react with the substances used in cleaning operations.
Dall’analisi dei residui alle fasi di pulizia di un impianto industriale
La funzione dell’attività chimica è duplice: da un lato deve massimizzare la decomposizione e la rimozione dei residui presenti sulle attrezzature, dall’altro deve mantenere i residui rimossi in soluzione (tramite dissoluzione o emulsione), evitando che questi si depositino nuovamente in altre zone dell’impianto. Spesso le due funzioni vengono esercitate da sostanze diverse, le quali, opportunamente dosate in acqua o altri solventi, costituiscono la soluzione detergente. Le operazioni di cleaning-in-place vengono inoltre effettuate utilizzando in sequenza diverse soluzioni detergenti in modo da massimizzare la rimozione dei residui e minimizzare l’impiego di sostanze chimiche. Il pH della soluzione detergente, grandezza che misura l’acidità o la basicità (alcalinità) della soluzione, è determinante per garantire l’efficacia dei fenomeni di decomposizione, dissoluzione o emulsione dei residui. La maggior parte delle sequenze di pulizia si fonda sull’impiego alternato di soluzioni che sono necessarie per la neutralizzazione.
Una tipica sequenza di pulizia completa impiegata nell’industria alimentare si articola secondo 8 fasi consequenziali:
- pre-risciacquo con acqua per rimuovere lo sporco grossolano;
- ricircolo di una soluzione alcalina per decomporre e disciogliere/emulsionare lo sporco residuo;
- risciacquo con acqua per rimuovere gli alcali residui, con eventuale recupero dell’acqua non contaminata;
- ricircolo di una soluzione acida per neutralizzare gli alcali residui e rimuovere i depositi minerali;
- risciacquo con acqua per rimuovere gli acidi residui;
- ricircolo sanitizzante per ridurre la carica microbica;
- risciacquo finale con acqua e con eventuale recupero dell’acqua non contaminata;
- flussaggio con aria per facilitare l’asciugatura.
From Residue Analysis to Cleaning Phases
The role of chemical activity is twofold: on the one hand, it must maximize the decomposition and removal of residues present on equipment, and on the other, it must keep the removed residues in solution (via dissolution or emulsification), preventing them from redepositing elsewhere in the system. Often, these two functions are carried out by different substances, which, when properly dosed in water or other solvents, make up the cleaning solution. Clean-in-place (CIP) operations are also conducted using different cleaning solutions in sequence to maximize residue removal and minimize the use of chemicals. The pH of the cleaning solution—a measure of the solution’s acidity or alkalinity—is a key factor in ensuring the effectiveness of residue decomposition, dissolution, or emulsification. Most cleaning sequences rely on alternating solutions to achieve neutralization.
A typical complete cleaning sequence used in the food industry consists of the following eight consecutive phases:
- Pre-rinse with water to remove coarse dirt.
- Circulation of an alkaline solution to decompose and dissolve/emulsify residual dirt.
- Water rinse to remove residual alkalis, with possible recovery of uncontaminated water.
- Circulation of an acidic solution to neutralize residual alkalis and remove mineral deposits.
- Water rinse to remove residual acids.
- Sanitizing circulation to reduce microbial load.
- Final water rinse with possible recovery of uncontaminated water.
- Air flushing to facilitate drying.
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Specific Solutions for Each Type of Action
Alkaline Solution
The most aggressive action is provided by the alkaline solution, typically made with sodium hydroxide or potassium hydroxide, which can decompose most organic residues. In an alkaline environment, carbohydrate- and protein-based residues decompose rapidly, while fat-based residues (which are insoluble in water) are emulsified with the aid of elevated temperatures.
Acidic Solution
The action of the acidic solution, typically made with phosphoric acid or peracetic acid, is aimed at removing mineral deposits (e.g., those resulting from heating hard water rich in calcium and magnesium ions) and neutralizing residual alkaline solutions.
Sanitizing Solution
In the food industry, a sanitizing treatment (e.g., ozone, chlorine dioxide, hydrogen peroxide, quaternary ammonium compounds, etc.) is often necessary to destroy harmful microorganisms such as bacteria, viruses, or fungi. All chemically active phases are usually followed by water rinse phases to remove any residual solution. The characteristics of the water used, particularly its hardness, are critical for the effective and efficient design of the cleaning sequence.
The Importance of CIP System Characteristics for Industrial Hygiene Standards
The design of cleaning sequences must consider the nature of the products being processed and the characteristics of the system. However, even an optimally designed sequence cannot compensate for poorly designed and implemented equipment.
In the food industry, every component—whether in direct contact with the processed product or not—must be designed and manufactured following specific protocols to minimize product stagnation zones and the potential proliferation of harmful microorganisms.
The following aspects are particularly important in this context:
- used materials,
- surface finishes,
- treatments applied to equipment,
- quality of the welds.
G-CLEAN: il sistema CIP customizzato di Granzotto
Il team di Granzotto, consapevole delle problematiche associate alla pulizia degli impianti nell’industria alimentare, realizza sistemi customizzati per garantire l’affidabilità e l’efficienza delle operazioni di pulizia e sanitizzazione. I sistemi CIP realizzati da Granzotto prendono il nome di “G-CLEAN” e vengono sviluppati per garantire la massima pulizia in tutte le zone di contatto con il liquido, come tubazioni, valvole, pompe, serbatoi e macchine riempitrici. Nelle versioni skid, i sistemi CIP vengono realizzati con particolare attenzione alle finiture e alle saldature degli elementi strutturali. I sistemi G-CLEAN consentono di effettuare le operazioni di pulizia degli impianti in modo efficace e nel minor tempo possibile.
G-CLEAN: Granzotto’s Custom CIP System
The Granzotto team, aware of the challenges associated with cleaning systems in the food industry, develops customized systems to ensure the reliability and efficiency of cleaning and sanitizing operations. Granzotto’s CIP systems, known as “G-CLEAN,” are designed to guarantee thorough cleaning in all contact areas with the liquid, such as pipelines, valves, pumps, tanks, and filling machines.
In their skid-mounted versions, CIP systems are manufactured with particular attention to the finishes and welds of structural elements. The G-CLEAN systems allow cleaning operations to be performed effectively and in the shortest possible time.
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