The success of new product introductions lies with consumer acceptance of key food attributes such as texture, color, flavor, freshness, and nutrition. Automation in food processing allows for control of the consistency of these attributes by measuring a specific property, adjusting processing conditions to maintain the attribute associated with the property, comparing the measurement to predefined specifications and through computer control, adjusting the process to maintain overall consistency. Such automation is essential to the establishment of dynamic, flexible, and competitive manufacturing technologies. Well positioned, on-line sensor technology is at the core of efficient process control and assurance of high product quality. Measuring physical and chemical attributes of food materials in real-time must be achieved to meet process control targets and ensure product quality. Traditional measurements, done off-line in a laboratory, are performed under controlled conditions. Since these situations do not mimic actual processing conditions, such measurements will obviously be of limited usefulness for real-time process control.
[...] Conclusion On-line sensor technology is currently emerging to address both process efficiency and quality improvement in food processing operations. Processing of food products is complex, involving many steps which, when controlled, can have a direct effect on the quality of the product as perceived by the consumer. To control a food process, sensor technology can be coupled with process control systems. This technology can take many forms, from simple physical measurements of material weight and ingredient size, to complex analytical chemical and biosensors which can measure chemical reactions as they are occurring during food production. [...]
[...] This overall effort allows the development of new sensors which address industrial needs, with shared technology development risk by the companies and sensor manufacturers, offset by government funds. Many other contributions from linkage of individual research organizations and instrument and sensor manufacturers are also bringing new sensor technology forward. It is important to remember that it is only in recent times that sensor manufacturers developed the capability to manufacture sensors which can be used in food processing environments. This is due to the emergence of new materials, new micro fabrication and miniaturization strategies, and the development of knowledge-based computer technologies such as fuzzy logic and expert system neural networks which help accommodate for the variability in process measurements. [...]
[...] Research at the Center for Advanced Food Technology is beginning to result in on-line sensor prototypes that address moisture with new sensors. Other moisture sensors are in development to address the higher temperatures encountered in ovens. Infrared systems are being used to examine on-line product moisture at various process stages. To assist in making these measurements, instrument manufacturers have been developing unique on-line test cells and increasing the measuring distance from the test cell to the remainder of the instrumentation with better fiber optics and microelectronics to allow on- line use. [...]
[...] This device cannot be used on-line in food processing operations due to its fragile glass structure. To overcome this problem, ISFET sensors became important. The development of an ISFET sensor, particularly for pH measurement, was aimed at overcoming the hazard of the fragile membrane of the ion-selective electrode. Various insulating oxide films such as Si02 and AI2O3 have been investigated to optimize performance of the ISFET over a wide range of processing conditions since this type of sensor is influenced by a variety of ionic materials, and temperature. [...]
[...] Color monitoring with infrared technology and color machine vision also have new on-line quality measurement capabilities to determine, for example, the effects of thermal processing on peas and carrots. Machine vision provides new techniques for inspection and placement of packaged food placeables, and certain inspections for product packaging. Electrically-based sensing Electrically-based sensing often uses ceramic or polymer materials that specifically correlate emf (voltage), impedance, or dielectric constant with the desired measurement property. A sensor, placed into an electrical circuit, reacts with moisture, heat, pressure, or some other property in the food environment, or by chemical reaction with the food system, causing a perturbation in the electrical properties of the sensing material. [...]
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