Solving production moisture problems

Food safety scares in both the US and Europe have drawn food processors' attention to desiccant dehumidification systems, which ensure the right levels of humidity within food production facilities.

Ensuring the correct moisture and condensation levels for food production is crucial, particularly for the meat industry, and with food health and safety regulations becoming all the more stricter, this has now become an essential element to production. This area of work has become the mainstay of US-based company Munters Moisture Control.

In the US, the Department of Agriculture (USDA) require control of condensation on ceilingsand other overhead surfaces that may drip onto, and possibly contaminate, meat or other food products being processed.

With incidents this past year of pathogen contamination that have resultedin meat recalls, assuring public safety and confidence is a vital challenge in the meat processing industry. Also, from an economic standpoint, a shutdown of an operating line for a violation can be costly.

Contributing to moisture buildup inside a plant are various factors, such as water vapours released during slaughtering and processing, cooking processes and temperature differentials.

Controlling the potential for condensation by ensuring moisture levels is growing rapidly as an engineered solution. Some facilities constructedwithin the past three years have been designed to meet the tougher regulations. Older plants, however, have turned to ancillary controlmethods.

Initially, plant engineers sought to control moisture by increasingair conditioning. While that procedure provides some dehumidification, itusually is not sufficient to eliminate condensation. Nor is it possiblesolely through air conditioning to hold an acceptable range of humidity.

Now, desiccant dehumidification is being applied as a response.Compared to the typical refrigeration system, desiccants are effective inremoving moisture from the air without condensing or at extremely lowtemperatures. While cooling-based dehumidifiers cool the air to condensemoisture and then drain it away, desiccants attract moisture moleculesdirectly from the air in a vapour phase using a unique desiccant wheel. Themoisture is released by the desiccant when heated in an exhaust air stream,avoiding the hazards of condensation altogether.

While some plants have invested in permanent equipment, other facilities managers have opted to rent before purchasing - either as a wayof testing effectiveness or to respond to an immediate or temporary need.

Rental units are often used as the initial solution to a moisture problem within a meat processing plant. Rental units ranging from 150 scfmto 9000 scfm are usually available within a 24 hour period to quickly solve moisturerelated problems that can stop or limit production. Additionally, this isan effective solution until capital can be appropriated for permanentequipment as rental costs typically are paid out of the operating budget.

In addition to avoiding potential sanitation issues related to condensation and moisture, there are other benefits to controlling ambientmoisture, including reducing wash-down fog and freeze-up in refrigeration units.

The Bagel Bites Division of H.J. Heinzdemonstrated the process by employing desiccant dehumidification provided by Munters Moisture Control.The Bagel Bites Division makes pizza-topped mini-bagels in a choice ofnumerous topping combinations, many of which include meat.

The production facility in Florida strictly complies with USDA wash-down regulations. The process is alsocompleted under Ore-Ida's written Sanitation Standard Operating Procedures(SSOP) adopted under the HACCP government mandate food safety system.

Each night, during the third shift, production is suspended for the wash-down. At the onset, the normal temperature in the processing room is atabout 45ºF. The cold air is so close to saturation that it cannot absorbthe large amounts of water vapour being sprayed into the room from the wash-down hoses. As a result, water being sprayed precipitates out, immediately forming fog and condensation throughout the room.

Once the wash-down is completed, all equipment, walls and floors must bedried and made free of any water or condensation. In particular, anyoverhead condensation that could drip onto the product must be eliminated toavoid any potential for contamination posed by moist, wet conditions.

With relative humidity close to 100 per cent during and after the wash-down, the total time needed to dry the processing area exceeded four hours. Little improvement was gained to minimise drying time by using cooling from the air conditioning system, circulation fans, squeegees and moppingstanding water.

The company was enthusiastic about the desiccant dehumidification concept foraddressing their fogging and condensation issues, but reluctant to committhe capital investment in a technology they had not previously used.

As an alternative, the company rented a 9,000 scfm unit to evaluate resultsin controlling moisture. On the first day of operation with the rental unit,the wash-down was started and fog filled the processing area. The dehumidifier was then started. Within 15 minutes, all the fog was clearedfrom the room.Munter also claim that in addition to clearing the fog, the unit continued to run after the wash-down to allow drying of the equipment, walls, floors and ceilings in thearea. The drying time was reduced significantly. With the dehumidifier inoperation, the wash-down took little more than two hours.

Following the first night of evaluation, Bagel Bites was convinced of thedehumidifier's capabilities purchased its own equipment.

The permanent dehumidifier now processes 9,000 scfm, delivering dry air conditions of77ºF at 4 per cent RH. The cooling units operate in response to athermostatic control. A humidistat holds the room to 65 per cent RH, anappropriate level to prevent condensation and fog while also meeting foodproduction specifications.

Along with eliminating the fog and condensation, Bagel Bites has found thatits dehumidifier purchase has benefits that reach beyond the processingarea. Several process freezers, located inside the dehumidified area, haverealised a significant reduction in both frost accumulation and defrostcycles, according to Munters.

Munters Dehumidification Division is headquartered in Glendale Heights, Illinois and is North America's largest water damagerecovery/temporary humidity control company.