NEAR-INFRARED REFLECTANCE SPECTROSCOPY FOR ANALYSIS OF SUGARCANE FROM CLONAL EVALUATION TRIALS .2. EXPRESSED JUICE

The analysis of fibrated sugarcane (Saccharum spp. hybrids) with near infrared reflectance spectroscopy (NIR) offers the possibility of replacing standard laboratory analyses for quality components, including sugar and fiber content. Analysis of expressed juice by NIR spectroscopy does not provide an estimate of fiber content, but has the advantage of using a more uniform sample. This approach has potential application in early selection stages, and also offers considerable promise for process control in manufacturing. This research aimed to assess NIR spectroscopy for analysis of quality components of juice. Two replicated trials provided samples of cane from which juice was expressed. Quality components were analyzed by routine laboratory methods. Samples of juice were scanned in a transflectance cell of a Technicon 450R NIR spectrophotometer to provide transflectance data (log 1/TF). Independent calibration and prediction experiments were conducted. Correlation coefficients from the tests of prediction were: Brix (0.97), CCS (0.97), conductivity (0.47), impurity (0.63), polarimetry (pol) reading (0.98), and purity (0.58). Skew for prediction regressions was significant for all components except CCS. Bias was significant for CCS. The NIR and routine lab analyses differed significantly for all components except Brix. The bias and skew resulted from problems associated with fouling of the transflectance cell by particulate matter. Acceptable calibrations were obtained from data from a closed population in one experiment. Sampling analyses of spectrophotometer readings (log 1/TF) indicated duplicate determinations were unnecessary. The standard of determination of quality components of juice by NIR spectroscopy approaches that required for clonal evaluation.