
%0 Journal Article
%A Guthrie, J. 
%A Walsh, K. 
%T Influence of environmental and instrumental variables on the non-invasive prediction of Brix in pineapple using near infrared spectroscopy
%J Australian Journal of Experimental Agriculture
%D 1999/03/17
%V 39
%N 1
%P 73-80
%K 
%R https://doi.org/10.1071/EA96127
%U https://www.publish.csiro.au/paper/EA96127 
%X Summary. The Brix content of pineapple fruit can be non-invasively predicted from the second derivative of near infrared reflectance spectra. Correlations obtained using a NIRSystems 6500 spectrophotometer through multiple linear regression and modified partial least squares analyses using a post-dispersive configuration were comparable with that from a pre-dispersive configuration in terms of accuracy (e.g. coefficient of determination, R2, 0.73; standard error of cross validation, SECV, 1.01&#176;Brix). The effective depth of sample assessed was slightly greater using the post-dispersive technique (about 20 mm for pineapple fruit), as expected in relation to the higher incident light intensity, relative to the pre-dispersive configuration. The effect of such environmental variables as temperature, humidity and external light, and instrumental variables such as the number of scans averaged to form a spectrum, were considered with respect to the accuracy and precision of the measurement of absorbance at 876 nm, as a key term in the calibration for Brix, and predicted Brix. The application of post-dispersive near infrared technology to in-line assessment of intact fruit in a packing shed environment is discussed. 
