UV spectroscopy and multi-product multivariate calibration in the determination of the total acidity in industrialized juices

Abstract

<p>The determination of the total acid using UV spectroscopy and multi-product multivariate calibration is presented as an alternative to the conventional method through potentiometric titration. The model was developed including different products (fruit nectar of different flavors and light fruit nectar) where outliers samples were identified and excluded. Partial least squares (PLS) regression was used in order to build the model. Accuracy, represented by the values of the Root Mean Squared Errors of Calibration (RMSEC) and Prediction (RMSEP) were 0.0641 and 0.0534 mg/100 mL, respectively. The confidence ellipse confirms that accuracy was achieved at 99 % confidence, while residues showed random behavior, confirming linearity for the model developed. The proposed methodology shows advantages as fastness, does not requires sample preparation and does not generate toxic waste, being an alternative to the conventional method based on potentiometry.</p><p> </p><p>DOI: 10.14685/rebrapa.v6i1.177</p>

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

“…Correlation coefficient to the fit of the multiproduct model, presented by plotting the reference values against the estimated values, was 0.7188 for vitamin C and 0.7435 for total acidity. These values were considered satisfactory since previous research reported coefficient values around 0.7, when the reference method was the titration method (Valderrama, Braga, & Poppi, 2007a;2007b;Ferreira, Pallone, & Poppi, 2013;Santos et al, 2015;2016). The results presented in Table 2 and Figure 2 show that the multi-product PLS model results in more 'dispersed' results for vitamin C, which may be justified by the fact that the vitamin C is oxidized quickly, when in the presence of oxygen.…”

“…The total acidity (mg 100 mL -1 ) was determined, in triplicate, according to the Federation International des Producteurs de Jus de Fruit (2005) and to the methodology described by Santos et al (2015).…”

“…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.…”

“…Industrialized juices have been gaining consumer preference because of their practicality. In this sense, fruit nectar -which is defined as an unfermented drink ready for consumption, that is obtained from the edible part of the fruit diluted in potable water, and that may or may not be added with sugars, acids (Santos et al, 2015) or soy. The soy juices preserve the desirable sensory characteristics of fruits, along with the functional properties of soybeans, such as the presence of bioactive compounds such as isoflavones.…”