Vitamin C Determination by Ultraviolet Spectroscopy and Multiproduct Calibration

Abstract

In this work the vitamin C was determined in industrialized nectar juices through ultraviolet (UV) spectroscopy and multiproduct multivariate calibration, based on partial least squares (PLS) regression. Since samples with different flavors, sugar content (light or not) were together in the model construction, it can be considered as a multiproduct and, due to the heterogeneity of the samples, it was necessary to optimize the calibration and validation sets by outliers elimination. The model was developed and validated by the evaluation of the figures of merit such as: accuracy, sensitivity, analytical sensitivity, adjust, linearity, relative prediction deviation, limits of detection and quantification, indicating that the multiproduct model developed from UV spectroscopy and PLS regression can be used in the industrial routine analysis as an alternative to titration or other time and reagent consuming methods. Here, it was evidenced that the UV-PLS multiproduct model provides advantages as being free of sample preparation steps, is suitable to be updated in order to measure other parameters, does not generates residues and is feasible to be implemented for on-line monitoring. Furthermore, the application of multivariate calibration in multiproduct models is extremely attractive from the industrial point of view.

Brazilian Coffee Blends: A Simple and Fast Method by Near‐Infrared Spectroscopy for the Determination of the Sensory Attributes Elicited in Professional Coffee Cupping

“…Astringency and bitterness presented the highest correlation coefficients, around 0.8, whereas for other attributes the correlation coefficients are in the range of 0.73 to 0.79. For multivariate calibration models elaborated from results obtained with high variability (as in this case), a correlation coefficient up to 0.7 can be considered satisfactory (Beltrame et al., ; Santos et al., ). In addition, it is known that the correlation coefficient is directly related to the errors embedded in the execution of the reference method, in this case, the “cupping test.” This method of analysis requires preparation of the coffees by percolation of roasted and ground coffee for further analysis and demands tasters with a high level of experience in coffee tasting, capable of distinguishing and quantifying the sensory attributes.…”

“…Multivariate models were validated by the determination of the parameters of merit such as accuracy, fit, linearity, residual prediction deviation, sensitivity, analytical sensitivity, and limits of detection and quantification, according to the description presented in the scientific literature (Beltrame et al., ; Santos, Lima, Março, & Valderrama, ).…”

“…Astringency and bitterness presented the highest correlation coefficients, around 0.8, whereas for other attributes the correlation coefficients are in the range of 0.73 to 0.79. For multivariate calibration models elaborated from results obtained with high variability (as in this case), a correlation coefficient up to 0.7 can be considered satisfactory (Beltrame et al, 2016;Santos et al, 2016). In addition, it is known that the correlation coefficient is directly related to the errors embedded in the execution of the reference method, in this case, the "cupping test."…”

“…presented in the scientific literature (Beltrame et al, 2016;Santos, Lima, Março, & Valderrama, 2016).…”

Multi-product multivariate calibration: determination of quality parameters in soybean industrialized juices

“…The successful use of the PLS regression method in the development of multi-product multivariate calibration models is recent (Rambo, Amorim, & Ferreira, 2013;Santos, Março, & Valderrama, 2013;Santos, Lima, Março, & Valderrama, 2015;2016). The use of the PLS method by the industrial sector has been growing and gaining more and more space.…”