On-line inspection of poultry carcasses using visible/near-infrared spectrophotometer

The Instrumentation and Sensing Laboratory (ISL) has developed an industrial prototype diode-array visible/near-infrared (Vis/NIR) spectrophotometer system for inspecting poultry for diseased and defective carcasses on-line. The ISL design is based on the principle that wholesome and diseased and defective birds have different chemical compositions of tissues and may have different skin color. This visible/near-infrared spectrophotometer system has been tested off-line at 60 and 90 birds per minute. On-line trials of the visible/near-infrared chicken carcass inspection system were conducted during an 8-day period in a slaughter plant in New Holland, Pennsylvania, where spectra (470-960 nm) of 1174 normal and 576 abnormal (diseased and/or defective) chicken carcasses were measured. The instrument measured the spectra of veterinarian-selected carcasses as they passed on a processing line at a speed of 70 birds per minute. Classification models using principal component analysis as a data pretreatment for input into neural networks were able to classify the carcasses from the spectral data with a success rate of 95%. Data from 3 days can predict the subsequent two days' chickens with high accuracy. This accuracy was consistent with the results obtained previously on off-line studies. Thus, the method shows promise for separation of diseased and defective carcasses from wholesome carcasses in a partially automated inspection system. Details of the models using various training regimens are discussed.