Chlorine Gas Systems for Fruits and Vegetables Packing

To ensure the safety of fruits and vegetables, it is essential to implement robust disinfection methods that effectively reduce microbial contamination while preserving the quality and nutritional value of the produce. Chlorine disinfection has proven to be a highly effective and widely used method in the fruit and vegetable industry (Sun et al., 2012). Chlorine kills a broad spectrum of disease-causing pathogens, including bacteria, viruses, and fungi, making it an ideal choice for disinfection purposes. Furthermore, chlorine has the advantage of leaving a residual disinfectant in the water, providing ongoing protection against microbial growth and recontamination.

The application of chlorine disinfection is prompted by the need to safeguard public health and prevent foodborne illnesses associated with fresh produce consumption. By implementing proper disinfection protocols and utilizing chlorine-based solutions, growers, packagers, and distributors can significantly reduce the risk of microbial contamination and ensure the safety of fruits and vegetables for consumers.

Hydrogen peroxide is another alternative disinfection agent that has gained attention in various industries. It exhibits strong antimicrobial activity and is effective against bacteria, viruses, and fungi (Lineback et al., 2018). Hydrogen peroxide is relatively safe to use and leaves no harmful residues, as it breaks down into water and oxygen. It also has the advantage of being compatible with a wide range of materials, making it suitable for different surfaces and commodities. However, its efficacy can be influenced by factors such as concentration, contact time, and environmental conditions.

Peracetic acid, also known as peroxyacetic acid (or PAA) is a highly effective disinfectant with broad-spectrum antimicrobial activity. It is known for its rapid action and ability to inactivate various pathogens, including bacteria, viruses, and spores. Peracetic acid exhibits strong oxidizing properties and has low toxicity compared to other disinfectants. It can be used for surface disinfection as well as for the treatment of water used in processing fruits and vegetables (AMS USDA, 2000). However, it is known to be highly corrosive and can cause severe burns to the skin (NJ DOH, 2004). It is important to handle peracetic acid with caution because of its hazardous properties.

Further alternative methods for disinfecting produce have emerged, including Ultraviolet (UV) light, Non-Thermal Plasma, and Pulsed Electric Fields (PEF). UV treatment utilizes UV-C light to destroy microbial contaminants without affecting produce quality, but it has limited penetration capabilities and requires sufficient exposure time and uniform illumination. Non-thermal plasma shows promise with rapid disinfection and minimal impact on sensory attributes, but further research is needed to optimize operating parameters and assess long-term effects. PEF treatment effectively reduces microbial populations while preserving quality, but challenges remain in equipment design, treatment uniformity, and scalability for large-scale disinfection. While these methods offer innovative approaches, careful consideration is required to address their limitations and ensure their effectiveness in fruit and vegetable disinfection processes.

Equipment Selection

Hydro Instruments Products

To ensure optimal disinfection of fruits and vegetables using chlorine, Hydro Instruments offers a range of specialized products designed specifically for this purpose. The following equipment solutions are recommended to achieve efficient and controlled chlorine disinfection:

Gas Feed Systems

Hydro Instruments’ gas feed systems are designed to facilitate the controlled and efficient introduction of chlorine gas into the water used for washing, dipping, or showering produce. These systems are equipped with high-quality gas regulators, flow meters, and control valves to ensure accurate and consistent chlorine dosing. By maintaining precise control over chlorine gas dosage, the gas feed systems enable effective disinfection while minimizing wastage and ensuring the safety of operators.

Chlorine Gas Detectors

Safety is a paramount concern in chlorine disinfection processes. Hydro Instruments provides chlorine gas detectors that continuously monitor chlorine gas levels in the packing area or any other relevant space. These detectors are designed to promptly detect any potential leaks or elevated concentrations of chlorine gas, triggering alarms to alert operators. By providing early warning of hazardous conditions, the chlorine gas detectors help prevent accidents, safeguarding the well-being of personnel and ensuring a secure working environment.

Residual Analyzers

Monitoring the chlorine residual levels in the washing water is crucial to maintaining the desired disinfection efficacy. Hydro Instruments offers residual analyzers that accurately measure the concentration of free or total chlorine in real time. These analyzers provide operators with instant feedback on the chlorine residual levels, allowing them to make timely adjustments to chlorine dosing if necessary. By ensuring the proper chlorine residual concentration, the residual analyzers help optimize disinfection efficiency and maintain the desired level of microbial control.

By utilizing Hydro Instruments’ gas feed systems, chlorine gas detectors, and residual analyzers, operators can establish a comprehensive chlorine disinfection system for fruits and vegetables. These reliable and innovative equipment solutions offered by Hydro Instruments contribute to enhanced process control, increased safety, and consistent disinfection performance, ultimately ensuring the safety and quality of the produce.

Typical Setup

The water used for washing, dipping, or showering the fruit should be chlorinated and maintained at a level of 50 to 200 PPM to prevent the microbial contamination of produce at the facility. This level is easier to maintain if the water is first filtered or run through a flocculation process to remove organic material, which would otherwise bind with chlorine to form disinfection by-products with carcinogenic properties such as chloramines (CGA, 1998).

Chlorine must be continuously added to the water to replace that used in reactions with organic matter, chemicals, microorganisms and the surfaces of citrus fruits (UM, 2002). Hydro Instruments offers the necessary equipment to automatically measure free Chlorine concentrations and to add Chlorine to the water when needed.

In a typical fruit-packing plant, a stainless-steel container filled with water maintains a chlorine residual concentration of 100 PPM. A small dosing pump is used to add sodium hypochlorite to the smaller-sized trough used in the application. To monitor chlorine concentration and other chemicals (such as ozone, hydrogen peroxide, peracetic acid, and bromine), packing houses often utilize the RPH-250 Probe-type Residual Analyzer. This analysis helps determine the necessary dosing of sodium hypochlorite to maintain the required residual concentration. Fruits are usually picked up from the water by a conveyor belt and transported along a long stainless-steel trough where workers remove leaves before retrieving the fruit at the end for packing. In the case of vegetable applications, the vegetables are typically sprayed with antimicrobial agents for disinfection before being sent for packing.

Figure 1: Gas Chlorination System for fruit & vegetable hydro cooling or washing.

In order to determine the correct capacity of Hydro Instruments chlorination equipment, the water flow must be known. Water is used as an ingredient, an initial and intermediate cleaning source, an efficient transportation conveyer of raw materials, and the principal agent used to sanitize plant machinery and areas (AEP, 2005). Because a packing house may range from a simple, on-the-farm thatched shed to an automated regional packaging line handling large tonnages of a single commercial crop, water consumption will vary. A very rough approximation of water usage during blanching is one gallon of water for each pound of produce and two gallons of water for each pound of leafy produce (Roberts/Cox, 2001). In any case, the following formulae are used to calculate the dosage needed for the washing step:

Imperial Units: Gallons Per minute (GPM) x 0.012 x Parts per Million (PPM) = Pound per Day (PPD) Metric Units: Liters Per minute (LPM) x 0.06 x Parts per Million (PPM) = Gram per Hour (g/hr)