Design, Construction, and Testing of an Automated NIR In-line Analysis System for Potatoes. Part I: Off-line NIR Feasibility Study for the Characterization of Potato Composition

Abstract

An off-line near-infrared reflectance (NIR) feasibility study was conducted to explore the critical steps in the NIR determination of the major potato constituents (dry matter, starch, and protein) in relatively large (10 kg) potato samples. The results were important for the design of an automated industrial analysis system for potatoes with in-line NIR. The 10-kg potato samples were pulped with an industrial rotary saw blade rasp. A critical step in the NIR measurements was the occurrence of phase separation in the potato pulp. Phase separation manifests itself directly after pulping the potatoes and significantly affects the NIR spectrum. Therefore, during the NIR measurements, the potato pulp had to be stirred continuously. The NIR spectra (1,100-2,500 nm) were measured by applying an optical fiber NIR probe (EDAPT-1) connected to the NIR spectrophotometer (Technicon Infralyzer IA 500). NIR models for the concentration of dry matter, starch, and coagulating protein in potatoes have been developed. With the partial least squares regression procedure, promising NIR models were calculated. The NIR models were validated using an independent validation set of potato samples. The root mean square error in prediction of the samples in the validation set was 0.5% (w/w) for dry matter, 0.63 (w/w) for starch concentration, and 0.06% (w/w) for the coagulating protein.

Design, Construction, and Testing of an Automated NIR In-line Analysis System for Potatoes. Part II. Development and Testing of the Automated Semi-industrial System with In-line NIR for the Characterization of Potatoes

“…They stated that the main reason for the low predictive ability of these models was caused by the problem of measuring the minor constituent protein in a matrix with a major constituent starch and bulk water. However, as reported (Brunt and Drost 2010), phase separation rapidly occurs in pulped potatoes, and this affects strongly the quality (accuracy and precision) of the developed NIR models. Brunt and Drost (2010) presented in Part I of these series of two manuscripts the results of an off-line NIR feasibility study, which was conducted to explore the critical steps in the NIR determination of the major potato constituents (dry matter, starch, and protein) in relatively large (10 kg) potato samples.…”

“…However, as reported (Brunt and Drost 2010), phase separation rapidly occurs in pulped potatoes, and this affects strongly the quality (accuracy and precision) of the developed NIR models. Brunt and Drost (2010) presented in Part I of these series of two manuscripts the results of an off-line NIR feasibility study, which was conducted to explore the critical steps in the NIR determination of the major potato constituents (dry matter, starch, and protein) in relatively large (10 kg) potato samples. This feasibility study proved that reliable NIR models and thus measurements can be obtained from large pulped potato samples, as dealt with in industrial systems.…”

“…Calculated expected potassium concentration (% (w/w)) for sample 3 0.522 0.524 0.527 0.531 0.533 0.538 a Maximal acceptable carry-over according to design demands AVERAGE average constituent concentration in the sample set, RANGE constituent concentration range in the sample set, STDRANGE standard deviation in the sample set, STDREF standard deviation of the reference analysis, STDRATIO ratio between the standard deviation in the in the sample set and the standard deviation in the reference analysis (STDRANGE/STDREF) (Brunt and Drost 2010), a Technicon 500C NIR instrument was applied with a wavelength range of 1,100-2,500 nm. In the present study, a new industrial NIRSystem 6500 NIR instrument was applied with an extended wavelength range of 400-2500 nm, thus incorporating also the visible region.…”

“…This feasibility study proved that reliable NIR models and thus measurements can be obtained from large pulped potato samples, as dealt with in industrial systems. The most critical step in the NIR measurements was the occurrence of phase separation in the potato pulp (Brunt and Drost 2010). Phase separation manifests itself immediately after pulping the potatoes.…”

“…The results were of decisive importance for the continuation of the project to develop and construct a semi-industrial, fully automated system, applicable to the characterization of the quality of the truckloads of potatoes delivered at the potato starch factory. Based on the positive results of our feasibility study (Brunt and Drost 2010), it was decided to continue the project and to design and construct a semi-industrial, fully automated system with in-line NIR equipment for the characterization of the composition of the potatoes.…”