ORIGINALLY PUBLISHED IN THE FOOD QUALITY & SAFETY MAGAZINE
Written by Kelly Froehlich, marketing content manager at Spec Engineering, and Kevin Laud, vice president of engineering, at CandyWorx.
Weather and humidity are factors that we deal with daily, whether inside or outside. Quality issues within food and beverage products can be traced back to inconsistencies in humidity levels, and even the slightest humidity fluctuation can require procedural changes. Hygroscopic substances absorb moisture, and a small change in humidity will impact the consistency of the product, including during the material separation phase.
This article will evaluate the importance of regulating humidity, the impacts of high and low humidity, best practices for controlling storage conditions, and recommended equipment to control humidity. Examples will highlight the confectionery industry, where high sugar content in these sweet treats accelerates the products’ sensitivity to humidity fluctuations.
Importance of Regulating Humidity
Humidity is not present in only one industry; it affects all processing industries. It’s important to recognize where humidity is present and rectify the situation quickly. Maintaining control over humidity is necessary to ensure that a consistent, high-quality product is produced, that performance is optimal for manufacturing processes, and that a product is stored correctly when it is ready to be consumed.
The issue of various humidity levels can play a role at any stage, even as early as particle separation. Hydroscopic powders absorb water from humidity in the air, which increases the cohesion and decreases the ability to flow. If a material were to expand when introduced to humidity, the particles could form together as they expand. Powdered materials that clump together as the humidity rises will end up halting production at some point due to their moisture level and inability to be properly processed. The challenges that are faced when processing materials in different parts of the country or in environments that experience multiple seasonal changes must be considered for proper processing techniques.
Aside from the inconvenience of lost product or decreased revenue due to incorrect humidity levels, there are serious implications to keep in mind. When an increased level of moisture is present, there is the risk of microorganism growth even in areas that are usually clean. Airborne bacteria can grow without the proper airflow, which is then passed along to the food.
Suddenly, there is a much larger problem than an inconsistent product. Humidity that is too high or too low can also foster mold or bacteria growth, leading to decreased shelf life.
The Impact of High and Low Humidity
As humidity levels fluctuate, product will become more difficult to transfer or convey because it is absorbing moisture, weighing more, and becoming stickier. Over time, conveying lines will start to clump and cake up, decreasing the pneumatic rate and slowly clogging the line. Aside from lower efficiency, sanitary concerns begin to rise when lines are clogged. When humidity levels are not balanced, plant maintenance teams will need to service the lines more frequently, causing downtime in the systems.
Knowing this, effective process systems that battle humidity will be equipped with a dryer or desiccant dryer that will help to dry the product properly. Other process systems will be integrated with delumping or declumping devices, which will combat the clumping and prevent clogs. In mechanical or pneumatic transfer systems, knowing and understanding the humidity level is key to ensuring a consistent rate of transfer.
In the confectionery industry specifically, inconsistent humidity levels lead to many product issues, most of which are visible to the naked eye. Candy is typically made of sucrose and corn syrup, both of which are highly hygroscopic. Effects of high humidity on confections include a cloudy appearance, grainy and irregular coatings, and sugar blooms. Products may experience sticky, runny, or high-water content in the product, as the product cannot cool properly. These issues may result in lower shelf life and the cost of returned or spoiled products from consumers. Confectionery products experiencing lower humidity will be more fragile; product may crack as it dries too quickly. Dry material is also more abrasive, causing the equipment to wear at an increased rate. Appearance of product is very important for confectionery products, so high or low humidity levels strongly affect the “shelf appeal” of these products.
Best Practices for Controlling Storage Conditions
Aside from having the proper process in place to combat humidity challenges, establishing best practices for controlling storage conditions will also benefit the product. If certain storage containers are introduced to the wrong level of humidity, they may begin to deform, separate, or break. Paper packaging will become soggy, and metal packaging can begin to corrode. Packaging is designed to protect the food or beverage product, so alterations to the packaging due to humidity could affect the safety of the product inside.
Recommendations for candy storage suggest 40% relative humidity (rh), with dry air, sometimes with the help of an air conditioner unit. Panned confectionery products should have storage conditions at 40% to 50% rh. The rh value is important to avoid sticking or cracking of the product. An ideal manufacturing environment will take into consideration where the ingredients are stored before the process and where the product is stored before shipping to its final destination.
Recommended Equipment to Control Humidity
Identifying and utilizing the proper equipment throughout a system is crucial when controlling humidity. For products that are engrossed in chocolate or yogurt, an enclosed belt coater is a reliable way to uniformly coat product while avoiding moisture build-up. Automated belt coaters can alleviate the moisture that could be introduced in a process like hand coating products.
Spray dryers can produce a dry powder from liquids/slurries, as the product is quickly dried with a hot gas. Heat-sensitive and heat-resistant foods benefit from this process. The final product is improved as the stickiness decreases. Spray dryers are fully automated and continuous, which allows for higher output.
For confectionery products, a cooling tunnel ensures that products passing through are in a controlled environment. Cooling tunnels can offer batch or continuous processes, and a slow drying of the product provides efficient and reliable cooling. Cooling tunnels can be equipped with a cold air diffuser at the top of the tunnel with a separate return air elsewhere. Insulated doors and sides help keep outside environmental factors away from the product.
Gummy products are also very specific when it comes to their environment.
Although an automated depositor is ideal for gummy depositing, the production environment plays a large role that the machine cannot account for. While being deposited, the gummies must cool and gel for a dedicated amount of time to achieve the proper moisture content. Many gummy edibles today rely on “starchless” technology, meaning that they are deposited into flexible silicone molds, and then cool and gel before being removed from the molds and finished with an oil or a sugary coating.
Due to this process, gummies can easily be affected by a 1% to 2% change in moisture. If the gummies sit out too long, they can turn hard or crusty. If they are pulled from the mold too quickly, they will be slimy and sticky. Having the proper air conditioning, dehumidifiers, dryers, and more will avoid a messy situation. In the end, it is not only about the processing equipment but also the equipment throughout the whole production space that plays a role in producing the end product.
All of the above equipment must consider how moisture is present within the mass it is processing. For instance, large pieces sent quickly through a dry atmosphere will only leave the outside surface dry, while the center still retains high moisture. Residence times must be accurately controlled such that internal moisture can transfer within the particles themselves.
Although the original humidity level is out of the manufacturers’ control, controlled environments and processes can be created for specific products and industries. Evaluating the products’ characteristics and reactions to humidity and weather will be important indicators for what a final process should consist of. What might be the perfect dry air for one product could be a nightmare for the next. By combining the right process with the right equipment and environment, products will benefit, realizing repeatable results, less downtime, and higher efficiency. Thinking through the ingredients, processing, and storage side of the situation will allow products to succeed.