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From: Food Quality & Safety magazine, October/November 2012

Philip Nelson's Aseptic Bulk Storage Revolutionized Global Food Trade

by Lori Valigra

Inspired by the harvest food losses he saw while working at his father’s Indiana tomato canning factory as a child, former Purdue University professor Philip E. Nelson, PhD, developed aseptic bulk storage and distribution technology that would ultimately revolutionize the global food trade.

And while he accomplished that seminal work in the 1960s and 1970s, Dr. Nelson believes it’s just as relevant today as the world faces future food shortages. “We’re looking at having to double food by 2050,” he said, reiterating a 2009 estimate from the U.N.’s Food and Agriculture Organization. “And that’s not just producing more. It also involves storage and processing.”

Memories of the tomato spoilage losses, which amounted to 10% to 20% of the crop, prompted Dr. Nelson to look for a solution. At 15, he was introduced to Purdue University’s extension system after winning that organization’s 4-H award for the 24 perfect tomatoes he had entered at the Indiana State Fair, according to biographical information provided by Purdue in 2007, when he won the World Food Prize. His 4-H accomplishment earned him the title of “Tomato King.”

Born in 1934, Dr. Nelson earned his bachelor’s degree in general agriculture from Purdue in 1956. He returned home to Morristown, Ind. and became plant manager of the family-owned tomato cannery, Blue River Packing Co., according to information released in 2010 by Purdue when it renamed its food science building after Dr. Nelson. When his father Brainard closed the cannery in 1960, Dr. Nelson worked for a time on the family’s 500-acre farm, raising hogs, corn, and beans. He then returned to Purdue, where he was offered a paid assistantship in horticulture, which he accepted to support his wife, Sue, and their daughter. He earned his doctorate in 1967; the Tomato King’s dissertation topic focused on the volatility of flavor in canned tomatoes.

He considered positions in the food industry, interviewing with several companies in New York, Chicago, and other cities. On a flight to an interview, Dr. Nelson sat next to the dean of Purdue’s College of Agriculture, Earl Butz, PhD, who later served as U.S. Secretary of Agriculture under Presidents Richard Nixon and Gerald Ford. Dr. Butz advised Dr. Nelson to consult with him first before making a final decision about working in the private sector. When he did so, Dr. Butz offered Dr. Nelson a tenure-track faculty position at Purdue, which led to his 50-year career at the university.

A chance meeting with the then-Dean of Purdue’s College of Agriculture led to Dr. Nelson’s 50-year career at the university.
A chance meeting with the then-Dean of Purdue’s College of Agriculture led to Dr. Nelson’s 50-year career at the university.

Inspired by the harvest losses he saw at his father’s Indiana tomato canning factory, Dr. Nelson developed aseptic bulk storage and distribution technology that would ultimately revolutionize the global food trade.

Working with Industry

Early on, Dr. Nelson understood the importance of collaborating with industry, as he focused on trying to eliminate the seasonality of commercial processing and packaging, as well as post-harvest spoilage. He worked side by side with equipment manufacturers in the private sector to design and build the tanks, valves, filters, and flexible bag containers necessary for storing processed food.

Aseptic processing involves sterilizing a food product that is, in turn, stored or packaged in a sterile container to maintain sterility. From his years of working in the family canning business, he knew that new methods to prevent post-harvest spoilage would be a big boost to the food processing industry and the consumer, according to his Purdue biography. Tomatoes were one of the world’s most processed foods, and Dr. Nelson questioned if they could be stored for long periods of time in tanks at ambient temperature aseptically, or free of pathogens, without becoming contaminated or spoiling. His aim was to hold large quantities of tomatoes to a date beyond harvest and then process them at intervals throughout the year into products such as sauces, juices, and ketchup. That, in turn, would make the tomato industry less seasonal. In recent years, it is estimated that more than 90% of the 22 to 24 million tons of tomatoes harvested globally are aseptically processed and packaged for year-round remanufacture.

In 1991, the Institute of Food Technologists ranked aseptic processing and packaging No, 1 among the top 10 innovations in food technology–ahead of juice concentrates, safe canning processes, freeze-drying, and food fortification. In 1995, Dr. Nelson was awarded the IFT’s prestigious Nicholas Appert Award, named after another food industry pioneer who was spotlighted in the February/March 2011 issue of Food Quality. Dr. Nelson served as IFT’s president from 2001 to 2002. While his name is often associated with pioneering work in aseptic processing and bulk storage, he credits other food safety pioneers who preceded him. They include C. Olin Ball, who started studying aseptic processing in 1927 at the American Can Company (see Food Quality June/July 2011 issue), and the developers of the Martin-Dole process, invented at the Dole Engineering Company in the 1940s.

The discoveries made in Dr. Nelson’s Purdue lab, along with his work with companies, dramatically transformed the vegetable and fruit packing industry from a fresh pack system where produce was produced once a year into a remanufacturing industry where products could be made year round from vegetables and fruits stores in large containers. Notably, with orange juice, bulk aseptic storage and transportation made possible the wide-scale distribution of not-from-concentrate juice.

At Purdue, Dr. Nelson’s first industry research sponsor was Enerfab, an engineering company in Cincinnati, Ohio, which made tanks for the beer industry. “While the Martin-Dole process was for small containers, mine was aimed at a large, 1,000-gallon container, though I started with a 100-gallon container in the lab,” Dr. Nelson explained. With student labor to help get the tomatoes aseptically processed and into the tank, Dr. Nelson was able to quickly move to larger and larger tanks—from 15,000-gallon tanks for a Pennsylvania company to tanks holding a couple of million gallons for Tropicana in the 1980s.

“Tropicana wanted to see if my technology would work with orange juice. That’s when not-from-concentrate became popular,” he said. He also worked with Brazilians on half million-gallon tanks that could be carried on ships worldwide.

Early on, Dr. Nelson understood the importance of collaborating with industry, as he focused on trying to eliminate the seasonality of commercial processing and packaging.

“The key technology is aseptic processing, with sterilized containers and products made sterile outside the container,” he said. “That made bulk storage possible.” Today, some citrus tanks are six stories tall and six stories wide.

Dr. Nelson said that because he was dealing with acidic foods such as tomatoes, he tested five different tanks with different linings and similar construction in the lab. He also looked into refrigeration, finding that it helps to protect the flavor as well as the vitamins. The contents underwent mild pasteurization before nitrogen was added. When stored at 40°F, the contents would keep for a year, he said. “The product is made just-in-time for the market,” Dr. Nelson explained.

Dr. Nelson credits rapid testing for improving food safety.
Dr. Nelson credits rapid testing for improving food safety.

Bringing Food to the Developing World

As his pioneering technology began to be used in many developing countries, it became clear that it significantly increased the availability and accessibility of food. According to his World Food Prize biography, Dr. Nelson was part of a National Academy of Sciences team that traveled to India in the 1970s to study food spoilage, which at the time affected up to 50% of all food produced in the country. That visit prompted Dr. Nelson to start exploring ways for his technology to be used in developing countries.

“In India, the loss after harvest at the time was 10% to 30% of products such as grains, rice, fruits, and vegetables. Up to 50% of mangoes were lost,” Dr, Nelson said. “In 2009, they were still losing that amount.”

He has started a center at Purdue called the International Food Technology Center to help small farmers get more of their food to the local market. He continues with those efforts today after retiring from Purdue in 2010. His technology was also used to transport potable water to Southeast Asia to provide relief after the 2004 tsunami, and to the U.S. Gulf Coast in 2005 following Hurricane Katrina. Though these applications were not aseptic, they did use flexible packaging that resulted from Dr. Nelson’s research.

Dr. Nelson said that today, industry and government are better at tracking and sourcing contamination or pathogens and making recalls before too many people get sick. He remembered that as a child, he fell ill to Salmonella poisoning from eggs in homemade ice cream.

“Rapid detection is making a big difference in food illnesses. Rapid methods are very important,” Dr. Nelson said. Nonetheless, pathogens still seem to find their way into the food supply. As such, he said, job security won’t go away. “There’s always going to be a job for a food scientist.”

Dr. Nelson has co-authored three textbooks, published more than 70 peer-reviewed articles, and generated 12 U.S. patents and 28 international patents, largely through his research in aseptic processing.


Lori Valigra is a frequent writer for Food Quality. Reach her at lvaligra@gmail.com.

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