A process developed by a researcher in Penn State’s College of Agricultural Sciences to extract high-quality pectin from orange peels may result in a new multi-million dollar American industry.

The new method, called flash extraction of pectin by steam injection, uses a high-temperature, high-speed procedure that
appears to be ideal for extracting high-quality pectin. The University has applied for a patent on the process.

Pectin is a complex carbohydrate found in fruits. A food additive, it is commonly used to thicken jellies and fruit fillings for pies and other desserts, and historically has been extracted from the peels of citrus.

In 2002, the United States imported more than 5,300 tons of pectin worth more than $56 million. Most pectin extraction is done in Europe using lime peels imported from Mexico and South America. For decades, pectin has been extracted mostly from lime peels by slow cooking. Pectin producers use lime peels because they produce higher-quality pectin than other citrus peels.

But that might be about to change. According to agricultural engineer Paul Walker, flash-extracted pectin from orange peels is comparable to or better than pectin from lime peels. “Of course, we have mountains and mountains of orange peels here because the United States is one of the largest producers of oranges in the world,” he says. “About 90 percent of the oranges we grow are used to produce juice.”

Agricultural engineer Paul Walker developed a process, for which Penn State has applied for a patent, to extract high-quality pectin from orange peels. The innovative process has the potential to spur a new multimillion-dollar American industry.

During a recent sabbatical at the U.S. Department of Agriculture’s Wyndmoor, Pa., facility—where he was developing techniques to remove microbiological contaminants from fruits and vegetables—Walker became interested in pectin-extraction
research being done there. Partnering with a USDA chemist, he began pondering better, faster ways of extracting pectin from peels.

“They were experimenting with using microwave energy for extraction,” says Walker. “As an engineer, I started thinking about the benefits of using steam injection to heat the peels quickly under pressure, and the benefits of extraction at high temperature, with rapid cooling.”

So he worked on the problem in his spare time for a year or so, developing equipment to do the process his way. During the research, Walker and his colleagues at Wyndmoor realized, to their delight, that they could get high-quality pectin from orange peels using the new, high-speed, high-temperature process. That discovery could result in the growth of a pectin-extraction industry in the United States using a source—orange peels—that now goes to waste.

“The ramifications of this research are enormous,” says Walker. “Big orange juice makers are very interested. It’s a simple process, but the best ideas are the simplest. As Einstein said, ‘Every thing should be made as simple as possible, but not simpler.’”

—Jeff Mulhollem