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  • Author or Editor: G. S. Birth x
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Abstract

In addressing the subject of nondestructive evaluation of internal quality of horticultural crops, the establishment of an understanding of quality is needed at the outset. Dull (4) has defined nondestructive quality evaluation (NDQE) as “a gaining of meaningful information which can be used in making judgments, both positive and negative, about the degree of excellence of a food with out altering the physical and chemical properties of that food.” In order to make judgments about a specific quality situation, one must select specific physical and/or chemical properties to be measured. A list of those properties would include weight, diameter, titratable acidity, pH, total nitrogen and concentration of soluble solids, sucrose, glucose, fructose, malic acid, citric acid, chlorophyll, carotene, anthocyanins, dry matter, proteins, amino acids, fat, starch, cellulose, pectins, and hemicellulose.

Open Access

An instrument based on near infrared (NIR) reflectance techniques is described which is capable of determining nondestructively the percent soluble solids in whole honeydew, cantaloupe and watermelon samples. It utilizes a tilting interference filter technology for wavelength scanning and a silicon detector/amplifier for the detection of radiation which has penetrated through inner melon flesh. The standard error of prediction is of the order of 1.2 percent soluble solids for honeydew melons when compared with a standard refractometer analysis.

Free access

A near-infrared spectrophotometric method for estimating the soluble solids in honeydew melons is presented. The method is based on a body transmittance geometry in which the angle between the source incident beam and the detector is approximately 45°. The regression analysis of the spectral and chemical data utilizes a ratio of two second derivatives and resulted in a correlation coefficient of 0.85 and a standard error of calibration of 1.5. The numerator wavelength occurs in a carbohydrate absorption band, thus the method can be interpreted as a measurement of carbohydrates.

Free access

Abstract

The techniques used in near infrared spectrophotometry for nondestructive analysis of agricultural products were applied to determine the percentage of dry matter (% DM) of intact onions (Allium cepa L). Transmittance data were recorded for the 700 nm to 1000 nm spectral region. Second derivative data processing was used with a stepwise multiple regression analysis to develop an equation to predict the % DM of individual onions. The correlation between optical data and % DM was 0.996. In a 2nd and completely independent experiment, we obtained equivalent results demonstrating the repeatability of the method. This repeatability was demonstrated even further through the satisfactory field testing of a portable instrument.

Open Access

Whole dates (Phoenix dactylifera L.) were analyzed for moisture content using near infrared spectrophotometry in a direct transmittance geometry. In the calibration experiment using 72 samples, the correlation coefficient was 0.977 and the standard error of calibration (SEC) was 0.89%. When the calibration equation was used to predict the moisture in another set of 72 date samples, the standard error of performance (SEP) was 1.5%. When the method was used to sort these 72 dates into four industry-standard grades, 74% were correctly graded and 15% missed the grade by <1 SEC.

Free access

Abstract

Body transmittance spectroscopy and analytical measurements of chlorophyll, carotenoids, and soluble solids concentrations were used to develop a nondestructive technique for estimating the maturity of papayas (Carica papaya L.). Optical measurements were taken between 500−900 nm with a scanning monochromator and a tilting-filter, abridged monochromator. Immature and mature-green fruit which were indistinguishable by visual examination could be separated by body transmittance spectroscopy into nonripening and ripening groups.

Open Access