Controlling dissolved oxygen (DO) levels during beverage production is vital to ensure consistent product quality and shelf life. This is particularly true for canning, where high DO levels can cause breakdown of the can lining, corrosion and even leaking – which in turn can result in product waste and customer dissatisfaction. In some cases, can supplier warranties have exclusions for high DO levels. Membrane contactors can be used to help manage dissolved oxygen in canning processes.
According to the Craft Brewers Association, cans have increased their share of craft beverage packaging from 2 percent in 2011 to 10 percent in 2014. It is no surprise, then, that craft beverage producers are looking for ways to combat DO during the canning process.
Vermont Hard Cider, maker of the well-known Woodchuck brand of ciders, began experimenting with canning in 2012 at its Middlebury, Vermont, facility. In 2014, the company decided to ramp up production of canned cider, but recognized that uncontrolled DO levels posed a threat to a consistent, high-quality product.
Many steps throughout the cider canning process allow for DO pickup. While some oxygen may be present after fermentation (~50 ppb) with additional pickup occurring during aging and filtration (500 ppb), the majority of DO is introduced during blending and tank transfer. Additionally, beverage producers using an inline filler may also see significant DO pickup in the final canning step unless careful DO prevention measures are in place.
Most manufacturers of cans void their warranties if DO levels are above 1,200 ppb in a canned product. Vermont Hard Cider noticed that even though DO concentration in the bright tank was within specifications at 200 to 500 ppb, it would occasionally experience DO levels above 1,200 ppb in canned products. The company determined that these DO levels were higher than anticipated because cider does not undergo fobbing foaming, which is commonly used in beer canning to prevent excess oxygen pickup.
Vermont Hard Cider searched for a solution that, starting with fully oxygenated liquid (8,000 ppb) at a flowrate of 25 gallons per minute, consistently delivered cider with 200 ppb or less at outlet. After research and speaking with other industry brewers, the company approached Quantum Flow Technologies, which designs and builds membrane contactor-based deaeration skids.
The membrane contactors use a microporous hollow fiber membrane to facilitate inline degassing of liquids without dispersion. The large surface area of the membrane allows the contactor to be compact, while efficiently deoxygenating large volumes of liquid at high flow rates. The small size of the membrane contactors enables compact systems that can be easily customized and scaled to meet various flow ranges and process configurations. Membrane contactors operate inline for rapid degassing with low head loss.
The final skid design incorporated two 8×20-inch stainless steel membrane contactors before the bright tank so that oxygen removal took place a close as possible to the final canning step (see Figure 1) to help reduce the opportunity for oxygen pickup in downstream steps.
The skid that incorporated membrane contactors was installed in 2015. Since then, Vermont Hard Cider has consistently achieved precanned cider with DO near 15 ppb, far exceeding the original target of 200 ppb. Moreover, the system functions the same under varying flow rates and is simple to operate and maintain.
To validate that the membrane contactors had little to no impact on the cider’s flavor profile, retention samples were evaluated at zero, three, six and 12 months. Results showed that the taste profile was consistent with cider prior to installation.
As canning grows in popularity among craft beverage producers, flexible and easily managed DO control solutions will be more important than ever. Thanks to Quantum Flow Technologies and 3M, Vermont Hard Cider has a DO control solution that it can count on – and easily expand – in the years ahead.
Amar Kapadia is the vice president of Quantum Flow Technologies (QFT). He led design and fabrication of the deaeration system featured in this article. He continues to support QFT’s membrane gas transfer systems sold throughout the world. He can be reached at firstname.lastname@example.org or 401-500-1692.
Ben E. Calvi is the general manager and cider master at Vermont Hard Cider Company/Green Mountain Beverage. He has been making wine and hard cider in California and Vermont for the past 12 years and holds a master’s degree in enology from UC Davis. He can be reached at email@example.com.