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Assessment of titratable acidity in fruit using short wave near infrared spectroscopy. Part A, Establishing a detection limit based on model solutions
journal contribution
posted on 2017-12-06, 00:00 authored by Phul SubediPhul Subedi, Kerry WalshKerry Walsh, DW HopkinsSpectra (700–2500 nm) of citric acid dissolved in water possess features interpreted as being due to the dilution and perturbation of water OH stretching and combination bands (with the second and first overtones of OH stretching at 960 nm and 1420 nm, respectively, and a combination band of OH vibration at 2132 nm) and also to citric acid OH stretching and combination bands and citric acid CH2 bands (first overtone of CH2 stretching at 1680?nm and a combination band of CH2 at 2284 nm). A searching window method was used to optimise the wavelength region for a partial least squares (PLS) regression model development (around 743–904?nm for the region below 1100 nm). Despite the apparent lack of information below1100 nm, a PLS regression model based on transmission spectra (743–904?nm) of pure citric acid–water mixtures (standard deviation = 6.65 g citric acid 100 m–1) yielded a root mean square error of cross-validation (RMSECV) of 0.34% and correlation coefficient of determination (Rcv2) = 0.998. However, if the matrix was varied with 0, 10 and 13% sucrose or fruit juice, RMSECV increased to 0.79%. This RMSECV value is proposed as a benchmark for attempts to assess titratable acidity of juice based on shortwave (700–1100 nm) near infrared spectra of intact fruit collected using silicon diode array instrumentation.
Funding
Category 1 - Australian Competitive Grants (this includes ARC, NHMRC)
History
Volume
20Issue
4Start Page
449End Page
457Number of Pages
9eISSN
1751-6552ISSN
0967-0335Location
United KingdomPublisher
SAGE PublicationsPublisher DOI
Full Text URL
Language
en-ausPeer Reviewed
- Yes
Open Access
- No
External Author Affiliations
Faculty of Sciences, Engineering and Health; Institute for Resource Industries and Sustainability (IRIS); NIR Consultant (Michigan, USA);Era Eligible
- Yes