A Century of Produce: The Rising Importance of Temperature
The following article from The Packer's “A Century of Produce,” was published in 1993.
As The Packer prepares to publish our 125th-anniversary edition later this year, we are posting some of the writing from previous anniversary publications.
Robert Kasmire writes of the positive impacts made in the produce industry from the development of temperature control.
The Rising Importance of Temperature
By Robert Kasmire
When one considers the many developments in the allied and technical fields that have contributed to advances in the produce industry during the past century, it boggles my mind to select only the major ones. Here are my suggestions for the outstanding ones:
> Recognition of the overwhelming importance of correct product temperature in maintaining product quality, along with the development of effective refrigeration systems to achieve desired temperatures, has to be the most important development. This includes advancing from cooling and storing in cool or primitive cold rooms to highly sophisticated, mechanically refrigerated systems, as well as developing and perfecting specific cooling methods, equipment and facilities to accommodate the cooling requirements of the countless types of produce and ornamentals we consume.
Hydrocooling produce was first recorded in 1921 when celery was cooled by immersion or sprayed with cold water in Sanford, Fla. Commercial manufacturing of hydrocoolers began in the late 1940s. Stericooler Union Ice Co., Clarksville Machine Works and Durand-Wayland Inc. were early manufacturers. Virtually all of the early hydrocoolers were ice-fired, with the water being cooled by contact with ice. Advances in design and components resulted in the carefully engineered, energy efficient, mechanically refrigerated hydrocoolers used in the 1990s.
Vacuum cooling, which uses a product’s heat to evaporate surface moisture, was developed to provide faster tobacco curing. It first was used commercially for cooling leafy vegetables in 1948.
The original installations were fixed installations and used steamjet evacuators. Vacuum coolers in the early 1990s used mechanical vacuum pumps, energy efficient compressors and sensing instruments that allowed operators to closely monitor and control the atmospheric pressure in the vacuum tube, enabling them to cool vegetables to just above their freezing points.
Recognizing that some vegetables -- celery, leaf lettuces and spinach -- wilted from the required amount of water loss from vacuum cooling led to the development of Hydro Vac cooling by Western Precooling Co., Fremont, Calif., in 1975. This process made possible successful vacuum cooling of more sensitive vegetables.
Hugo and Floyd Miller of Western Precooling and Gene Larsen of Mobile Products Services were the principal visionaries in developing the Hydro Vac process. In the beginning, the installations were fixed, but cooling advanced to one in which at least 95 percent of the coolers were capable of being moved to two or more locations annually, enabling shippers to cool vegetables in different districts as seasons progressed.
Forced-air or pressure cooling was the most widely used method in the early 1990s.
The concept for forced-air cooling was developed in about 1954 by Rene Guillou, an agricultural engineer at the University of California-Davis. Guillou recognized that creating a difference in air pressure across opposing sides of a vented package of produce caused the cooling air to flow directly over the product. This resulted in faster and more uniform cooling than room cooling.
Guillou demonstrated forced-air cooling to grape grower-shippers in Lodi, Calif., in 1955. The first commercial forced-air cooler was designed and developed by Diven Meredith, a mechanical engineer who recognized the adaptability of forced-air cooling for all kinds of produce. His company, Meredith and Simpson Co., Indio, Calif., built the state’s first forced-air cooler for grapes in Coachella Valley. A few years later, the first pressure cooler for strawberries was installed in Oxnard, Calif.
In the 1990s, forced-air cooling was the most widely used method for cooling produce and ornamentals. The cooling industry represented a capital investment of more than $1 billion and had an operations’ budget of several hundred million dollars worldwide.
>Other major developments in produce temperature management have been made in the fields of transport refrigeration and in wholesale, retail and foodservice handling of fresh produce.
Refrigerated marine containers and highway and trailer-on-flat-car trailers in the 1990s represented years of research and development in materials, design and construction advancements.
Uniform produce temperatures were being maintained within one or two degrees of a desired transit temperature.
The development of large-scale refrigeration systems with more expansive evaporator coils helped provide distribution cold rooms with higher relative humidities for maintaining produce freshness. This advantage also was achieved in installations using Filacells, filaments plus cells, the primary component in the HumiFresh system.
Specialized engineering firms, such as Food Plant Engineering Inc., also have made major contributions toward the better wholesale and distribution of produce. The need for and benefits from more careful handling of produce caused improvements in harvesting and packinghouse operations, packing, and packaging.
We progressed from bulge packing in large wooden containers and bulk products in jute bags to individually wrapped products in smaller standardized wood boxes, crates, lugs and flats in the 1990s.
Then came the slow but very visible change to fiberboard boxes (cartons) of seemingly countless designs, shapes, sizes and construction. Most of the time, the change was for economic reasons -- less expensive packing and/or packages and increased output -- but some changes were made because the carton provided better protection, including more effective cooling and product immobilization during transit.
Virtually all the research and development to improve carton manufacture, construction, design and assembly was done by the paper and carton manufacturing industry.
Design advances to accommodate uses specific to commodity needs were joint efforts by the carton and produce industry and often involved cooperative research groups. The change from hand stacking, loading and unloading to unitized handling, mostly on pallets, has been another example of progress. However, it stopped short of the financial benefits that could have been obtained from an industrywide adoption of Project Metrification, Unitization and Modularization’s proposed guidelines.
The development of plastic films with uniform and specific gas transfer capabilities greatly benefited produce packaging of consumer units of precut or lightly processed vegetables. Increased retention of product freshness increased consumer acceptance of prepackaged products. The large increase in sales and use of prepackaged salad mixes and lightly processed vegetables greatly benefited the foodservice industry.
>The development of modified- and controlled-atmosphere packaging, storage and transportation was another outstanding feat for the industry. From the discovery by two English scientists that some fruits benefited from CA storage to the 1990s commercial use of highly sophisticated, modified- and controlled-atmosphere systems, steady progress was made in this area.
Much of private sector research and development in the United States was done by the Whirlpool Corp. in the early 1960s. Some of this paralleled controlled- and modified-atmosphere research at various universities and at the U.S. Department of Agriculture. Results were promising and indicated opportunities for commercial development and application. But lack of adequate commodity response information to various conditions suggested the need for a cautious approach.
Whirlpool workers proposed and tested a system that kept lettuce and bananas under CA conditions from shipping point through retail. In supermarkets, consumers would select products from specially designed controlled-atmosphere chests. However, the cost-to-benefits ratio for such a system was not favorable and too many handling and technical problems existed to prevent its realization.
However, by 1966, three major corporations, Occidental Petroleum, Union Carbide and Whirlpool Corp., had developed their own systems for providing modified-atmosphere transport services. Others followed.
A major weakness in this movement was a tendency to promote, and sometimes even to promise, more than what was attainable. Whirlpool, however, recognized the limitations and in 1966 entered into a 50-50 joint venture with Bruce Church Inc., one of the United States’ largest vegetable growing and shipping firms, to form TransFresh Inc.
Jim Lugg, research and development director for the Church firm, became president of the new enterprise. Under his leadership, TransFresh continued to progress, continually researching commodity and technology problems and developing solutions. In addition to its own and cooperative research, TransFresh funded extensive university research of modified atmosphere and controlled atmosphere to provide information on product behavior and response to various atmospheres and conditions.
In 1973, Bruce Church’s heirs purchased Whirlpools’ 50 percent of the venture and formed Fresh International, the parent company of TransFresh. By 1992, more than 70 percent of California’s out-of-state fresh strawberry shipments were protected by the TransFresh-developed Tectrol modified atmospheres and pallet bag technology. More than 58 percent of Florida’s out-of-state berry shipments were similarly shipped that year. In the early 1990s, modified-atmosphere technology had a major role in the rapid expansion of the precut and lightly processed vegetable operations. Large-scale international shipments of asparagus, avocados, mangoes, cantaloupe and other commodities were possible by controlled-atmosphere technology and systems for marine containers.
Controlled-atmosphere storage technology progressed rapidly in several countries. Improved design and construction of CA storage facilities, the development of technology for monitoring and maintaining low ethylene concentrations and high relative humidities, and the ability to maintain proper concentrations of oxygen and carbon dioxide in storage advanced this development.
Its benefits greatly extended the shipping and marketing services for apples, pears and other commodities, and made it possible for consumers to enjoy the products almost year-round.
>The development of useful and meaningful grades and standards for most fresh produce commodities occurred slowly but steadily for decades. Cooperative efforts between industry and government have benefited the produce industry and the public.
The extensive research and educational programs of post-harvest handling and physiology contributed significantly to the more visible progress made in the industry during the last 100 years. This work was conducted by the USDA, universities, foreign government agencies, private companies and corporations. The early post-harvest work by the United Fruit Co. provided the basis for the 1990s banana handling technology. Numerous commodity advisory boards provided liaison and guidance with public research and educational agencies to demonstrate the need for specific research or educational programs. These boards subsequently funded requested programs and helped extend results to the fresh produce industry.
