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From: Food Quality & Safety magazine, June/July 2008

Food Processing Technology Evolves

Innovations can help you stay on top in a global marketplace

by Linda L. Leake

Welcome to the fast-paced world of food processing, a complex arena in which players must embrace strategic thinking to stay relevant and competitive in a demanding global marketplace. In this evolving world, several food-processing engineers are leading the way.

“I want the U. S. food industry to continue to be a model for the world relative to efficiency and product quality and safety,” says Craig Wyvill, chief of the Food Processing Technology Division (FPTD) at the Georgia Institute of Technology’s Research Institute in Atlanta.

Wyvill and colleagues are working on technologies designed to improve the efficiency and effectiveness of food processing operations, with special emphasis on poultry applications. So far, they’ve developed a range of continuous screening systems for everything from defective poultry carcasses to cooked sausage patties. These accomplishments evolved from their pioneering development of continuous inline screening and monitoring systems for various food processing applications using computer vision technology.

The researchers are also involved in a range of technology development areas, including robotics, information systems, bioprocessing, advanced separation systems, and sensor systems. “We are becoming much more involved in finding ways to help plants introduce more dynamic controls over processing operations,” Wyvill says. “To that end, we are turning more and more to computer simulation and modeling.”

But models are of limited value if you can’t measure dynamics, he says. “We see a growing need for more and better sensors with in-line continuous screening capabilities to pinpoint changes in critical parameters,” Wyvill says. “All foods pose challenges in measuring quality parameters, whether they be a natural product like fresh meat or a manufactured item, such as a sesame seed hamburger bun.”

Advanced sensor concepts that go beyond computer vision are already surfacing in processing operations, although many screening concepts remain confined to laboratory settings rather than on-line. This is beginning to change, Wyvill says. “We are starting to see online screening systems that can check product thermal profiles, fat content, and moisture content. We are also seeing breakthroughs that will eventually enable us to screen online for microbial contamination and chemical composition as product is being produced.”

Buns in the Oven

As leader for the FPTD Sensor and Information Technology Group, Doug Britton, PhD, is overseeing the development of a system that controls a high-volume bun oven based on the color of the product. The technology uses an imaging system that provides automatic feedback to the oven controls to ensure homogenous products, top to bottom, every time. The system will be field tested in a bakery by mid-July, Dr. Britton says.

Researchers are also working on methods that estimate the internal temperature of formed and cooked products. “The goal is to help producers in high-volume cooking operations ensure that all of their production is reaching the fully cooked internal temperatures necessary to kill any pathogenic bacteria,” Dr. Britton says.

An infrared camera is used to measure the surface temperature while a 3-D imaging system generates the product’s shape profile. Advanced thermal modeling techniques allow producers to establish an estimate of the internal temperature using these sensor inputs.

Dr. Britton’s group is exploring the use of multi-spectral, fluorescence, X-ray, three-dimensional, and conventional imaging to address a wide variety of food processing problems. These include detecting leaks in over-wrap packaging, detecting bone fragments in meat, performing portion analysis of whole muscle products, detecting foreign materials in the product stream, generating position and orientation inputs for robotic manipulators, and providing meaningful feedback to both machinery and human operators on the processing floor.

Nonthermal Processing

Nonthermal processing is a noteworthy approach to attaining minimally processed foods of very good quality, says Gustavo Barbosa-Cánovas, PhD, director of the Center for Nonthermal Processing of Food at Washington State University (Pullman, Wash.).

“Foods processed with nonthermal techniques are very safe and of excellent nutritional and sensory characteristics,” he says. “The benefits include reasonable cost and the potential for significantly extended shelf life compared to counterparts processed by conventional technologies.”

Nonthermal technologies include high-pressure, pulse electric fields, ultrasound, ultraviolet, dense-phase carbon dioxide, and the use of ozone. Foods that are good candidates for nonthermal processing include fruit juices, egg products, dairy products, oysters, salsas, dips, Spanish tapas, and sliced ham.

“Industrial adoption of these technologies has been slow but steady,” Dr. Barbosa-Cánovas says. “The amount of high-pressure equipment available in the food industry is growing exponentially, with the end result that consumers might pay premium prices for some food products aiming for superior overall quality.”

Novel thermal technologies, including ohmic heating, microwave, and radiofrequency sterilization, are also becoming available at the industrial level. “Nonthermal technologies are mostly utilized for pasteurization processes because of their own limitations,” Dr. Barbosa-Cánovas says. “Without question, there are a significant number of untapped niches for food processors, despite the fact that most nonthermal processes are not currently capable of sterilizing foods.”

One approach getting more attention is what Dr. Barbosa-Cánovas considers “a very neat exception” called pressure-assisted thermal processing, which uses an intelligent combination of time, temperature, and pressure to sterilize foods. “Through a U.S. Department of Defense-sponsored endeavor known as the High Pressure DUST [dual-use science and technology] Program, industry, academia, and the government have been working in partnership for a number of years to explore and develop this concept because the overall quality of the product is very appealing,” he says. The DUST partners are expected to file for approval of the process with the Food and Drug Administration by the end of 2008.

Ultraviolet Technology

John Pierson, leader of FPTD’s Environmental, Energy, and Food Safety Group, is maximizing ultraviolet technology to disinfect liquids like fruit juices, marinades, and brines. “Commercial viability may be here even though ultraviolet light does not penetrate very deep, so only a small amount of liquid can be disinfected at a time,” Pierson says. “U.V. disinfection can offer benefits because heat is not used, so proteins are not denatured.” A recently patented advanced mixing system makes it possible to present liquid uniformly to the light for the same amount of time.

“We have been focused on five-log disinfection of liquids that are relatively opaque to germicidal ultraviolet light,” Pierson says. “Many of these liquids will only transmit the required disinfection intensity less than one millimeter, so systems must have long exposure times or extremely large surface- to-volume ratios.”

The Georgia Tech patented advanced disinfection system addresses both of these issues by controlling the hydrodynamics. Much of the fundamental development has been conducted using computational fluid dynamics (CFD). Five-log disinfection of brines and raw juices has been successfully demonstrated under laminar flow conditions; Pierson and colleagues are now conducting the testing needed for FDA technology verification. The technology is available for licensing, he adds.

Pierson is also addressing water conservation, reuse, and recycling protocols relative to food safety and sanitation. “The goal is to improve food processing water conservation and reuse while ensuring that pathogen reduction strategies are not negatively impacted,” he says. “One application is in poultry processing. The results of pathogen testing are known well after processing. Establishing a methodology for assessing cost-effective solutions will better enable processors to refine their HACCP [hazard analysis and critical control point] plans as they look for improved water conservation and reuse technologies.”

Water usage has become an area that needs advanced sensor concepts and data acquisition and control for process feedback related to pathogen reduction strategies, Pierson says. Unfortunately, reliable sensors for real-time pathogen counts or matrix independent disinfection capacity do not exist. Water usage data is usually collected and logged manually by reading water meters at some frequency. With these limitations in mind, Pierson’s group is working on developing cost-effective technology that can achieve and maintain pathogen reduction.

Mechatronics

Gary McMurray, leader of FPTD’s Automation Group, focuses on mechatronics, a discipline that integrates mechanical design, electrical systems, and software. “Image processing and automation are having a huge impact on the food industry,” he says. “Sensory technology provides vision for a robot to guide its actions.”

His group is currently designing a food-processing robot that can survive the high-pressure wash down and chemical cleaning agents used at plants. The robot’s first application is loading raw meat into trays. The group is also working on getting the robot to do a precise shoulder cut of bird carcasses in order to maximize efficiency.

Another project under McMurray’s wing, so to speak, is the development of a prototype sensor that automatically detects chlorine levels in poultry chiller water. That’s important, because each year the U.S. poultry industry processes 20 billion pounds of chicken.

In one of the closing steps in first-processing, eviscerated and defeathered carcasses are dropped into an immersion chiller, which rapidly chills the carcasses to 40°F or below. To further ensure microbiological safety, processors add chlorine to sanitize and disinfect the chiller water. Because the level of chlorine can affect product quality and taste as well as disinfection efficiency, the chiller water must be constantly monitored.

“Image processing and automation are having a huge impact on the food industry,” McMurray says. “Key players need to maintain open eyes to the potential and focus on a vision of more efficient processing plants requiring fewer people and generating less waste.”

Computational Fluid Dynamics

The implementation of early-stage simulation tools, specifically CFD, is a burgeoning international and interdisciplinary trend that allows engineers to computer-test concepts all the way through the development of a process or system, according to Da-Wen Sun, PhD, director of Food Refrigeration and Computerised Food Technology at the National University of Ireland in Dublin.

“With the enhancement of computing power and efficiency and the availability of affordable CFD packages, the applications of CFD have extended into the food industry for modeling industrial processes, performing comprehensive analyses, and optimizing the efficiency and cost effectiveness of the new processes and systems,” says Dr. Sun, who has edited a book on the topic (“Computational Fluid Dynamics in Food Processing”).

Using a computational grid, CFD solves governing equations that describe fluid flow across each grid cell by means of an iterative procedure in order to predict and visualize the profiles of velocity, temperature, pressure, and other parameters.

CFD facilitates prediction of heat, mass, and momentum transfer, as well as optimal design in industrial processes. Specific applications of CFD in food processing industries include drying, sterilization, refrigeration, and mixing.

Robin Connelly, PhD, a food scientist with the University of Wisconsin-Madison, is using CFD to understand the flow and mixing action of industrial mixers as they impact wheat flour dough. “Simulation is not a replacement for experimentation but has been shown to offer several advantages over experiment-based approaches,” she says. “You can test new equipment designs without building prototypes. You can study systems where controlled experiments are difficult or impossible to perform.”

Additionally, scientists can conduct safety studies or accident scenarios without inducing unsafe experimental conditions. They can run detailed parametric studies to optimize equipment performance. And they can obtain extremely detailed results, which can then be easily post-processed to calculate a wide range of dependent results.

“As with any new thing, CFD simulation technology must be tested in carefully defined situations that allow us to validate the results before it can be trusted with the more complex situations typical of food processing systems,” Dr. Connelly says. “As that trust is established, and as computational techniques and computing capabilities continue to advance at an amazing rate, the use of realistic CFD simulation to test equipment designs, process models, and new ideas has the potential to revolutionize the way food engineers operate.”

Leake is a food safety consultant and writer based in Wilmington, N.C. Reach her at llleake@aol.com or (910) 799-4881.

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