Apples grown in Michigan taste great. Peterson Farms Inc., the largest privately owned fruit processor in the state and a family-owned and operated group of companies, makes good use of the fine locally grown fruit. The company takes pride in turning Northern Spy, Jonathan, Golden Delicious, Empire, Crispin, Ida Red, Rome, Granny Smith, Fuji, Gala and other premium varieties into high-quality, fresh-cut, frozen fruit and juice products. Peterson Farms is well-known for its line of frozen products, including apples, tart and sweet cherries, blueberries, peaches, plums, and asparagus. The company, based in Shelby, Michigan, also annually produces and markets over 125 million finished pounds of frozen fruit and asparagus.
In 2000, Peterson Farms established a juice processing operation to complement its fresh-cut and frozen fruit production while extending its brand. Five million gallons of juice now flow each year from a state-of-the-art juice processing facility designed by Goodnature InEx of Orchard Park, New York. Here, the by-products of the fresh-cut and frozen fruit production, including peels and cores, are processed along with whole apples to make juice of exceptional clarity and quality.
The core of the apple juice processing facility is its filtration system. Peterson Farms employs a once-through batch process utilizing a system containing 96 horizontally-mounted SUPER-G® tubular membrane modules from Koch Membrane Systems (KMS) of Wilmington, Massachusetts. Each of the three-inch diameter modules contains four one-inch diameter tubes, ten feet in length, for a total membrane surface area of 9.3 square feet.
“We chose the SUPER-G tubular membranes because we wanted a filtration system that could maintain high flow rates,” said juice plant manager Abe Frise III. “That meant choosing a robust membrane system that would not clog easily. The SUPER-G membranes have far exceeded our performance expectations.”
For nine months of the year, the system operates 24/7 and filters three 15,000-gallon batches of apple juice each day. “During peak harvest periods, we will sometimes run larger batches of up to 20,000 gallons,” said Frise. “At other times of the year, we use the system to filter sweet and tart cherries, blueberries, or whatever is available. Once, we even filtered carrot juice without any problem.”
Tubular membranes are designed to resist fouling and plugging in spite of the high concentration of solids in the feed stream, allowing the system to generate very high yields. During filtration, the juice flows from the inside to the outside of the tubular membranes, meaning the pressurized feed stream is pumped along the inside of the tube while filtered juice permeates through the membranes to the outside of the tube. Tubular membranes use a tangential, or crossflow, design whereby process fluid is pumped along the membrane surface in a sweeping action.
This high tangential flow across the membrane surface helps limit membrane fouling. Moreover, the relatively large, one-inch diameter of the SUPER-G tubes facilitates flow and enhances plugging resistance. An additional advantage is that the SUPER-G tubular membranes are constructed of polyvinylidene fluoride (PVDF), which has been shown to be less prone to fouling than other membrane materials. The resistance to fouling facilitates high stable flux rates and easy cleaning. The Peterson Farms juice plant is able to filter 50 gallons per minute. “The only pretreatment implemented runs the juice through a centrifuge in order to maintain high flux rates and to extend time between cleanings,” said Frise. “We are happy to avoid diatomaceous earth, fining agents, and other cumbersome and expensive pretreatment methods.”
At the end of each batch, the system is flushed with water. A once daily clean-in-place operation is required to remove organisms and avoid fermentation that could affect the taste. The CIP process utilizes caustic and caustic and chlorine rinsing cycles. “The excellent cleanability of the membranes is critical, as any residual solids would quickly ferment at 120 degrees Fahrenheit, the temperature at which the juice is filtered,” explained Frise.
The clear housing of the tubular membranes allows the operators of the filtration equipment to easily determine the existence and location of any problems. This has instilled confidence in the operators, who can ensure that the system is operating properly at all times.
“Our wholesale customers require that we deliver juice below 5.0 NTU, but we do much better than that, regularly exceeding our internal specifications which call for less than 1.0 NTU. At Peterson Farms, we are very happy with the performance and maintainability of our membrane system,” says Frise. “We are getting three to four years of life out of the membranes, and the bottom line is that we have been able to consistently produce a high quality product. With apple juice, that means a juice with better clarity and color. And that means that people can enjoy drinking juice that is of the quality that people have come to expect of Peterson Farms.”