Optics: measuring and testing – Plural test
Reexamination Certificate
2000-03-13
2003-01-28
Evans, F. L. (Department: 2877)
Optics: measuring and testing
Plural test
C356S326000, C356S402000, C250S910000, C209S588000
Reexamination Certificate
active
06512577
ABSTRACT:
FIELD OF THE INVENTION
The present disclosure relates generally to the use of the combined visible and near infra red spectrum in an apparatus and method for measuring physical parameters, e.g., firmness, density and internal and external disorders, and chemical parameters, e.g., molecules containing O—H, N—H and C—H chemical bonds, in fruit and correlating the resulting measurements with fruit quality and maturity characteristics, including Brix, acidity, density, pH, firmness, color and internal and external defects to forecast consumer preferences including taste preferences and appearance, as well as harvest, storage and shipping variables. With the present apparatus and method, the interior of a sample, e.g., fruit including apples, is illuminated and the spectrum of absorbed and scattered light from the sample is detected and measured. Prediction, calibration and classification algorithms are determined for the category of sample permitting correlation between the spectrum of absorbed and scattered light and sample characteristics, e.g., fruit quality and maturity characteristics.
BACKGROUND OF THE INVENTION
The embodiments disclosed herein has a focus on combined visible and near-infrared (NIR) spectroscopy and its modes of use, major issues in the application of NIR to the measurement of O—H, N—H and C—H containing molecules that are indicators of sample quality including fruit quality and in particular tree fruit quality.
Near-Infrared Spectroscopy Background: Near-infrared spectroscopy has been used since the 1970's for the compositional analysis of low moisture food products. However, only in the last 10-15 years has NIR been successfully applied to the analysis of high moisture products such as fruit. NIR is a form of vibrational spectroscopy that is particularly sensitive to the presence of molecules containing C—H (carbon-hydrogen), O—H (oxygen-hydrogen), and N—H (nitrogen-hydrogen) groups. Therefore, constituents such as sugars and starch (C—H), moisture, alcohols and acids (O—H), and protein (N—H) can be quantified in liquids, solids and slurries. In addition, the analysis of gases (e.g., water vapor, ammonia) is possible. NIR is not a trace analysis technique and it is generally used for measuring components that are present at concentrations greater than 0.1%.
Short-Wavelength NIR vs. Long-Wavelength NIR: NIR has traditionally been carried out in the 1100-2500 nm region of the electromagnetic spectrum. However, the wavelength region of ~700-1100 nm (short wavelength-NIR or SW-NIR) has been gaining increased attention. The SW-NIR region offers numerous advantages for on-line and in-situ bulk constituent analysis. This portion of the NIR is accessible to low-cost, high performance silicon detectors and fiber optics. In addition, high intensity laser diodes and low-cost light emitting diodes are becoming increasingly available at a variety of NIR wavelength outputs.
The relatively low extinction (light absorption) coefficients in the SW-NIR region yields linear absorbance with analyte concentration and permits long, convenient pathlengths to be used. The depth of penetration of SW-NIR is also much greater than that of the longer wavelength NIR, permitting a more adequate sampling of the “bulk” material. This is of particular importance when the sample to be analyzed is heterogeneous such as fruit.
Diffuse Reflectance Sampling vs. Transmission Sampling: Traditional NIR analysis has used diffuse reflectance sampling. This mode of sampling is convenient for samples that are highly light scattering or samples for which there is no physical ability to employ transmission spectroscopy. Diffusely reflected light is light that has entered a sample, undergone multiple scattering events, and emerged from the surface in random directions. A portion of light that enters the sample is also absorbed. The depth of penetration of the light is highly dependent on the sample characteristics and is often affected by the size of particles in the sample and the sample density. Furthermore, diffuse reflectance is biased to the surface of a sample and may not provide representative data for large heterogeneous samples such as apples.
While transmission sampling is typically used for the analysis of clear solutions, it also can be used for interrogating solid samples. A transmission measurement is usually performed with the detector directly opposite the light source (i.e., at 180 degrees) and with the sample in the center. Alternately the detector can be placed closer to the light source (at angles less than 180 degrees), which is often necessary to provide a more easily detected level of light. Because of the long sample pathlengths and highly light scattering nature of most tree fruit, transmission measurements can only be performed in the SW-NIR wavelength region, unless special procedures are employed to improve signal to noise.
NIR Calibration: NIR analysis is largely an empirical method; the spectral lines are difficult to assign, and the spectroscopy is frequently carried out on highly light scattering samples where adherence to Beer's Law is not expected. Accordingly, statistical calibration techniques are often used to determine if there is a relationship between analyte concentration (or sample property) and instrument response. To uncover this relationship requires a representative set of “training” or calibration samples. These samples must span the complete range of chemical and physical properties of all future samples to be seen by the instrument.
Calibration begins by acquiring a spectrum of each of the samples. Constituent values for all of the analytes of interest are then obtained using the best reference method available with regards to accuracy and precision. It is important to note that a quantitative spectral method developed using statistical correlation techniques can perform no better than the reference method.
After the data has been acquired, computer models employing statistical calibration techniques are developed that relate the NIR spectra to the measured constituent values or properties. These calibration models can be expanded and must be periodically updated and verified using conventional testing procedures.
Factors affecting calibration include fruit type and variety, seasonal and geographical differences, and whether the fruit is fresh or has been in cold or other storage. Calibration variables include the particular properties or analytes to be measured and the concentration or level of the properties. Intercorrelations (co-linearity) should be minimized in calibration samples so as not to lead to false interpretation of a models predictive ability. Co-linearity occurs when the concentrations of two components are correlated, e.g., an inverse correlation exists when one component is high, the other is always low or vice versa.
Application of NIR to Tree Fruit and Existing On-Line NIR Instrumentation: A growing body of research exists for NIR analysis of tree fruit. NIR has been used for the measurement of fruit juice, flesh, and whole fruit. In juice, the individual sugars (sucrose, fructose, glucose) and total acidity can be quantified with high correlation (>0.95) and acceptable error. Individual sugars can not be readily measured in whole fruit. Brix is the most successfully measured NIR parameter in whole fruit and can generally be achieved with an error of ±0.5-1.0 Brix. More tentative recent research results indicate firmness and acidity measurement in whole fruit also may be possible.
Only in Japan has the large-scale deployment of on-line NIR for fruit sorting occurred. These instruments require manual placement/orientation of the fruit prior to measurement and early versions were limited to a measurement rate of three samples per second. The Japanese NIR instruments are also limited to a single lane of fruit and appear to be difficult to adapt to multi-lane sorting equipment used in the United States of America. While earlier Japanese NIR instruments employed reflectance sampling, more recent instruments use transmis
Evans F. L.
Ivey Floyd E.
Liebler Ivey & Connor
LandOfFree
Apparatus and method for measuring and correlating... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus and method for measuring and correlating..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus and method for measuring and correlating... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3024130