Buhler_CH.qxp_C-Masters 2/28/18 5:02 PM Page 1

As seen in April 2018 PBE powderbulk.com Copyright CSC Publishing Case history

hen Kevin Martin set out ,” says Martin, president of to create a healthy , Martin’s Family Fruit Farm. “We Whe envisioned a product wanted the process to be one that Apples to with the crunchy texture of a potato could be scaled up and could make chip and without the added sugars a consistent product.” and preservatives of most snack Apples: products. To accomplish this, Martin’s Family Fruit Farm in Searching for a drying solution Ontario, Canada, took a portion of Drying a their yield to create a dried apple chip. To find a way to effectively dry the apples while retaining a fresh fruit healthy flavor, Martin turned to Bühler Martin knew the color and texture Aeroglide, a Cary, NC-based snack he wanted to achieve, but he needed drying equipment supplier to figure out a drying method and specializing in custom-built identify processing technology that solutions. could create a quality product. Apples are known to present characteristic browning after being The supplier’s team of food A family fruit farm uses a sliced, and some food processors engineers started by performing add sulfites to inhibit the browning various tests to address the multistage dryer to browning issue. Engineers tested create apple chips. reaction — something Martin didn’t want to do. several process methods similar to blanching, using ascorbic acid as well as different drying “We were looking to create a temperatures and retention times. healthy snack for people using After various tests, they determined

Martin’s Family Fruit Farm uses a multistage dryer to produce apple chips. Buhler_CH.qxp_C-Masters 2/28/18 5:02 PM Page 2

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the correct process needed to product we wanted to make,” reduce browning, that could also Martin says. “It was key for us to achieve a crispy, low moisture chip make the investment in lab tests to that would hold its flavor. ensure that we purchased equipment that was going to achieve our goals.” The next step was to design a drying process for the apple chip. It was The engineers considered key quickly determined a multistage variables, including the apples’ AeroDry dryer would fit the thickness, drying time, and the application, since multiple drying dryer’s temperature set points. Dryer’s conveyor belt speed stages would be required to properly Drying experiments started with can be adjusted, along with the dry the apple slices. The multistage testing cored apples sliced in air temperature and flowrate, dryer provides gentle drying while different ways (some with the peel on to provide the desired results. maintaining color uniformity and and some without) by exposing them structure by adjusting the dryer’s to the multistage drying process. The supplier tested Crispin, configuration to each material type These tests helped engineers and processing conditions. These , , , and determine the precise thickness apples, and each equipment adjustments can include needed for the apple slices to dry, and conveyor belt speeds, temperature, variety reacted differently to the still remain crisp while retaining the variables with changing colors and and airflow conditions across the most fruit flavor. Next, they tested multiple drying stages. The dryer textures. During the testing the thickness or material bed depthof process, the engineers waited for uses zoned temperature controls to the layer of chips on the dryer’s customize the thermal process and the apples to develop the proper conveyor belt. If the chips were piled texture, before cooling down the maximize the heat-transfer too high, the apples would stick efficiency. apple product. Then, the final test together and if they weren’t piled was conducted by dropping the high enough, the process wouldn’t apple wheel onto the lab floor. The dryer also has pitched floors be economically feasible. When the dried apple wheel broke for easy washdown and open access apart, the process had achieved the for thorough cleaning, making the Another challenge was determining product characteristics that Martin dryer ideal for food processing wanted. applications that require sanitary when to reorient the apple chips equipment. without breaking them, how much heat to apply initially, and how “The equipment has worked as long that heat needed to be applied. anticipated,” Martin says. “There “We performed multiple lab-scale After trying several different was a learning curve with the dryer, tests to ensure that the process was airflow and temperature levels, but it has performed consistently, repeatable and to ensure we were each process stage was optimized to and we have increased the size of getting the right type of dryer for the get the required product quality. the dryer by two thirds since the original installation.” PBE

Note: Find more information on this topic in articles listed under “Drying” in Powder and Bulk Engineering’s article index in the December 2017 issue or the Article Archive on PBE’s website, www.powderbulk.com. (All articles listed in the archive are available for free download to registered users.)

Bühler Aeroglide Cary, NC Multiple tests were performed to determine what type of apple 800-722-7483 and apple slice thickness would be best to make the chips. www.buhlergroup.com/drying