Confectionery Manufacturing

Confectionery Manufacturing

Moisture Measurement in Confectionery Manufacturing Processes

TIM 025 07.97

One of confectionery manufacturers' worst fears is high humidity in their production facilities. Candy quality deteriorates when humid conditions exist in three primary areas; coating, cooling, packaging and storage areas. These areas require a means of dehumidification, especially if the plant is located in a region of the country known for having high humidity. Dehumidifiers come in three types; refrigerated, desiccant, or a combination of the two. A refrigeration unit removes moisture by cooling the air until moisture condenses. The air is then re-heated to lower the relative humidity. A desiccant dehumidifier removes moisture by exposing the air to desiccant material, which removes moisture from the air through absorption. The desiccant dehumidification unit is more efficient at removing moisture, is capable of producing drier air, and is more expensive than a refrigeration unit.

Coating

One of the most widely used coating techniques is pan coating. The term pan comes from the coating apparatus used to coat soft-center candy with a harder candy shell. This would include candy with soft jelly centers, chocolate centers, centers with combinations of chocolate and nuts, and many others. The coating pans are used to apply the outer coating onto the raw centers as they tumble in a large drum. Spray nozzles mounted inside the pan coater drums evenly distribute the liquid to form of the outer coating shell. Heat is applied to the pans so that the liquid in the coatings evaporates and the hard shell is formed. If the heated air blowing through the pans is too moist, the drying times are significantly longer and, therefore, the throughput is greatly diminished. The drying of the coatings applied in pans becomes the critical factor in maximizing the throughput in this entire production cycle.

The General Eastern HygroTwin 2850 series moisture analyzer and MDR series relative humidity probes monitor coating pan operations with excellent results. By monitoring the inlet and outlet air to the pans the user gains a valuable "window" into the drying cycle. By using the four analog outputs in the HygroTwin the temperature and moisture content of both air streams are monitored continuously. The probe on the inlet air side of the pan can warn the production supervisors of temperature and humidity conditions that fall above or below the optimum range. The performance of the dehumidification unit supplying dried air to the inlet of the pan can be monitored. If a failed dehumidification unit went undetected, entire batches of candy, typically 2000 pounds, would be ruined.

The probe on the outlet side of the pan could warn operators of excessive temperature that could burn the candy. The moisture content of the exhaust air is the most critical process variable. The production personnel can determine the end of the drying cycle based on this variable. In this way the HygroTwin allows the manufacturer to know when the candy is properly dried. Unloading under-dried product could result in clogged conveying systems. Over-dried product could result in loss of entire batches.

Cooling

Temperatures of air flowing through cooling tunnels can be lower if the dehumidification units have lowered the moisture content. Dry air in the cooling tunnels prevents condensation that could drip on the candy, and lower temperatures save energy costs.

Fast, uniform cooling is the only way to achieve even coating thickness on the exterior of candy with soft-coatings, such as chocolate covered bars. If the cooling air was not uniformly dehumidified, thin coatings near the top of the candy and "skirts" (thick coatings) at the bottom could result.

Packaging and Storage

Dehumidified air translates into faster packaging processes and longer shelf lives in storage areas. Lowered humidity also means less risk of mold and fungus accumulation in processing areas.

The General Eastern HygroTwin 2850 and RH-Plus 2250 moisture analyzers with MDR series moisture probes and MMR 31 series transmitters have frequently been used to monitor and control the operation of dehumidification units. Because so many critical manufacturing processes rely on the proper function of dehumidification units General Eastern equipment has even been used to replace existing OEM relative humidity sensors provided with dehumidification units. Only tight control of the temperature and humidity can produce optimal production. One of a manufacturers’ highest goals is to increase production. The General Eastern HygroTwin 2850 and RH-Plus 2250 moisture analyzers and MMR-31 transmitters accomplish just that.