Quality evaluation of frozen guava and yellow passion fruit pulps by NIR spectroscopy and chemometrics

Abstract

The present study investigated the application of near infrared spectroscopy as a green, quick, and efficient alternative to analytical methods currently used to evaluate the quality (moisture, total sugars, acidity, soluble solids, pH and ascorbic acid) of frozen guava and passion fruit pulps. Fifty samples were analyzed by near infrared spectroscopy (NIR) and reference methods. Partial least square regression (PLSR) was used to develop calibration models to relate the NIR spectra and the reference values. Reference methods indicated adulteration by water addition in 58% of guava pulp samples and 44% of yellow passion fruit pulp samples. The PLS models produced lower values of root mean squares error of calibration (RMSEC), root mean squares error of prediction (RMSEP), and coefficient of determination above 0.7. Moisture and total sugars presented the best calibration models (RMSEP of 0.240 and 0.269, respectively, for guava pulp; RMSEP of 0.401 and 0.413, respectively, for passion fruit pulp) which enables the application of these models to determine adulteration in guava and yellow passion fruit pulp by water or sugar addition. The models constructed for calibration of quality parameters of frozen fruit pulps in this study indicate that NIR spectroscopy coupled with the multivariate calibration technique could be applied to determine the quality of guava and yellow passion fruit pulp.

Estimation of Ascorbic Acid in Intact Acerola (Malpighia emarginata DC) Fruit by NIRS and Chemometric Analysis

“…The use of such poor-predicting models was recommended for simpler classification analysis, such as high/low sorting. Satisfactory accuracy for prediction was reported by Alamar et al [27] using NIRS for modeling the ascorbic acid content on guava pulp. Lower variability on chemical data allowed the development of good-predicting models (RMSEP = 6.137 mg/100 g and R 2 p = 0.85) with a reduced number of samples (N = 45).…”

Quality pattern evaluation of frozen soursop pulps: an assessment based on chemical composition and chemometric analysis

“…Sample NP presented titratable acidity below identity and quality standards (0.6 g 100 g -1 ). This low value (0.49 ± 0.03) may be a consequence of the dilution of organic acids present in soursop due to water addition in frozen pulp processing (Alamar et al 2016). The titratable acidity of the other investigated samples ranged from 0.71 to 1.00.…”

“…This property may vary according to factors such as genetic variety of the fruits or climatic conditions, but the possibility of water addition at the pulping stage should not be ruled out, since this practice is common in the Brazilian northeast to facilitate processing and increase product yield (Bastos et al, 1998). Alamar et al (2016) reported that water addition in frozen guava and passion fruit pulps was the reason for high moisture and low soluble solids contents in some samples. The other soursop pulps analyzed in the present study presented soluble solids content within the Brazilian regulations.…”

An overview of the Brazilian contributions to Green Analytical Chemistry

“…Spectroscopy and chemometrics have been exploited for a diversity of applications, including the evaluation of distribution of lignin and cellulose at wood surfaces (Colares et al 2015), detection of adulteration in gasoline samples (Paulo et al 2012), estimation of octane number (mendes et al 2012) or quality of frozen guava and passion fruit pulps (Alamar et al 2016), as well as to evaluate waste frying oil blends (hocevar et al 2012). In agreement with the principles of GAC, the direct analysis avoids consumption of chemicals for sample preparation resulting in low waste generation.…”