Multispectral fluorescence lifetime imaging of feces-contaminated apples by time-resolved laser-induced fluorescence imaging system with tunable excitation wavelengths.

We recently developed a time-resolved multispectral laser-induced fluorescence (LIF) imaging system capable of tunable wavelengths in the visible region for sample excitation and nanosecond-scale characterizations of fluorescence responses (lifetime imaging). Time-dependent fluorescence decay characteristics and fluorescence lifetime imaging of apples artificially contaminated with a range of diluted cow feces were investigated at 670 and 685 nm emission bands obtained by 418, 530, and 630 nm excitations. The results demonstrated that a 670 nm emission with a 418 nm excitation provided the greatest difference in time-dependent fluorescence responses between the apples and feces-treated spots.

Potential of surface-enhanced Raman spectroscopy for the rapid identification of Escherichia coli and Listeria monocytogenes cultures on silver colloidal nanoparticles.

Surface-enhanced Raman (SERS) spectra of various batches of bacteria adsorbed on silver colloidal nanoparticles were collected to explore the potential of the SERS technique for rapid and routine identification of E. coli and L. monocytogenes cultures.

Fluorescence characteristics of wholesome and unwholesome chicken carcasses.

Each chicken carcass intended for U.S. consumers is mandated to be inspected by Food Safety and Inspection Service (FSIS) inspectors for its wholesomeness at the processing plants.

Three-color mixing for classifying agricultural products for safety and quality.

A three-color mixing application for food safety inspection is presented. It is shown that the chromaticness of the visual signal resulting from the three-color mixing achieved through our device is directly related to the three-band ratio of light intensity at three selected wavebands. An optical visual device using three-color mixing to implement the three-band ratio criterion is presented.

Two-color mixing for classifying agricultural products for safety and quality.

We show that the chromaticness of the visual signal that results from the two-color mixing achieved through an optically enhanced binocular device is directly related to the band ratio of light intensity at the two selected wavebands. A technique that implements the band-ratio criterion in a visual device by using two-color mixing is presented here. The device will allow inspectors to identify targets visually in accordance with a two-wavelength band ratio.

Two-wave-band color-mixing binoculars for the detection of wholesome and unwholesome chicken carcasses: a simulation.

Visual inspection of wholesome and unwholesome chicken carcasses with a novel two-narrowband color-mixing technique for optically enhanced binoculars is simulated. From mean spectra of wholesome, airsacculitis (air-sac), cadaver, inflammatory process (IP), septicemia-toxemia (septox), and tumor chicken samples, 10 nm wave-band pairs are selected using color difference and chromaticness difference indices for simulation of multitarget and single-target detection. The color appearance simulation uses the CIECAM97s color appearance model.

Detection of fecal contamination on apples with nanosecond-scale time-resolved imaging of laser-induced fluorescence.

Detection of apples contaminated with feces is a public health concern. We found that time-resolved imaging of apples artificially contaminated with feces allowed optimization of timing parameters for detection. Dairy feces were applied to Red Delicious and Golden Delicious apples.

Development of a simple algorithm for the detection of chilling injury in cucumbers from visible/near-infrared hyperspectral imaging.

Hyperspectral images of cucumbers under a variety of conditions were acquired to explore the potential for the detection of chilling-induced damage in whole cucumbers. Region of interest (ROI) spectral features of chilling injured areas, resulting from chilling treatment at 0 degrees C, showed the reduction of reflectance intensity over the period at post-chilling room temperature (RT) storage. A large spectral difference between good, smooth skins and chilling-injured skins occurred in the 700-850 nm visible/near-infrared (NIR) region.

Analysis of hyperspectral fluorescence images for poultry skin tumor inspection.

We present a hyperspectral fluorescence imaging system with a fuzzy inference scheme for detecting skin tumors on poultry carcasses. Hyperspectral images reveal spatial and spectral information useful for finding pathological lesions or contaminants on agricultural products. Skin tumors are not obvious because the visual signature appears as a shape distortion rather than a discoloration.

Optimal fluorescence excitation and emission bands for detection of fecal contamination.

Fecal contamination of food products is a critical health issue. To test the feasibility of the use fluorescent techniques to detect fecal contamination, fluorescence excitation and emission characteristics of fecal matter from cows, deer, swine, chickens, and turkeys in the UV to far-red regions of the spectrum were evaluated. To allow the optimization of the detection of fecal contamination on animal carcasses and cut meats, emission-excitation spectra of the feces were compared with spectra for animal meats.

Automated detection of fecal contamination of apples by multispectral laser-induced fluorescence imaging.

Animal feces are a suspected source of contamination of apples by disease-causing organisms such as Echerichia coli O157. Laser-induced fluorescence was used to detect different amounts of feces from dairy cows, deer, and a dairy pasture applied to Red Delicious apples. One day after application, detection for 1:2 and 1:20 dilutions was nearly 100%, and for 1:200 dilutions (<15 ng of dry matter) detection was >80%.

Multispectral laser-induced fluorescence imaging system for large biological samples.

A laser-induced fluorescence imaging system developed to capture multispectral fluorescence emission images simultaneously from a relatively large target object is described. With an expanded, 355-nm Nd:YAG laser as the excitation source, the system captures fluorescence emission images in the blue, green, red, and far-red regions of the spectrum centered at 450, 550, 678, and 730 nm, respectively, from a 30-cm-diameter target area in ambient light. Images of apples and of pork meat artificially contaminated with diluted animal feces have demonstrated the versatility of fluorescence imaging techniques for potential applications in food safety inspection.

Changes in structure and color characteristics of irradiated chicken breasts as a function of dosage and storage time.

Structural change and color characteristics of chicken breasts as a function of irradiation dose and subsequent storage process were investigated by visible spectroscopy and HunterLab measurement. Ratios of R(1)=A(485 nm)/A(560 nm) and R(2)=A(635 nm)/A(560 nm,) which are related to absorbances of the visible bands at 485 nm (metmyoglobin), 560 nm (oxymyoglobin), and 635 nm (sulfmyoglobin), suggested that relative amount of oxymyoglobin either increases as a result of irradiation, or decreases with the storage process. The plot of R(1) and R(2) versus storage time showed that the increments of both R(1) and R(2) are dose-dependent and that the relative amount of oxymyoglobin species in irradiated meats begins to decompose 7-12 days later than raw meats.