Use of NMR for the Analysis and Quantification of the Sugar Composition in Fresh and Store-Bought Fruit Juices

Abstract

NMR spectroscopy is traditionally taught to students during Organic Chemistry as a tool used for the determination of structures after synthesis. However, modern NMR spectroscopy has many important applications beyond structure elucidation, including molecular profiling of complex mixtures as biofluids and food samples. In this experiment, students collect a series of nonselective and selective 1D NMR spectra of natural and supermarket fruit juices and are asked to identify and quantify the sugars present. For the quantitative analysis of the juices, the students must use the ERETIC2 (electronic reference to access in vivo concentrations 2) method embedded in the NMR software.

Classification of Prunus Genus by Botanical Origin and Harvest Year Based on Carbohydrates Profile

“…Generally, the fruit juices’ spectra are dominated by α-glucose, β-glucose, sucrose, and fructose signals, having the highest concentration among all the other metabolites. These belong to the carbohydrates region of the spectrum, which is placed in the middle-frequency region of the spectrum between 3.0 and 6.0 ppm, and it is followed by, in terms of signal intensities, amino acids, aliphatic region (from 0.5 and 3.0 ppm), and phenolic region (from 6.0 to 8.5 ppm) [ 16 , 17 , 25 , 26 , 27 , 28 , 29 ]. When the 5.40 to 4.10 ppm region was investigated, a pair of duplets were observed at 5.22 and 4.63 ppm that correspond to α and β glucose hydrogen in position 1.…”

“…Fructose signals were in the range of 3.57 to 3.60, 4.10 to 3.99 ppm, and 3.68 to 3.77 ppm, while the peaks were found at 3.60 and 4.10 ppm. The identification of carbohydrates signals was possible by consulting the literature [ 15 , 18 , 25 , 26 , 27 , 28 , 29 ]. Thus, the relevant 1 H-NMR peaks obtained for the carbohydrates region are reported in Table 1 , and, for fruit juices’ classification, each signal was taken into account, this region summing a total of 38 signals.…”

“…In the same range was identified one more pair of duplets at 5.39 and 4.20 ppm, which were assigned to hydrogen in position 1 from glucose and position 2 from fructose found in the composition of a sucrose molecule. Among the investigated spectra, sucrose signals were also detected at 5.40, [15,18,[25][26][27][28][29]. Thus, the relevant 1 H-NMR peaks obtained for the carbohydrates region are reported in Table 1, and, for fruit juices' classification, each signal was taken into account, this region summing a total of 38 signals.…”

Classification of Prunus Genus by Botanical Origin and Harvest Year Based on Carbohydrates Profile

“…Generally, the fruit juices’ spectra are dominated by α-glucose, β-glucose, sucrose, and fructose signals, having the highest concentration among all the other metabolites. These belong to the carbohydrates region of the spectrum, which is placed in the middle-frequency region of the spectrum between 3.0 and 6.0 ppm, and it is followed by, in terms of signal intensities, amino acids, aliphatic region (from 0.5 and 3.0 ppm), and phenolic region (from 6.0 to 8.5 ppm) [ 16 , 17 , 25 , 26 , 27 , 28 , 29 ]. When the 5.40 to 4.10 ppm region was investigated, a pair of duplets were observed at 5.22 and 4.63 ppm that correspond to α and β glucose hydrogen in position 1.…”

“…Fructose signals were in the range of 3.57 to 3.60, 4.10 to 3.99 ppm, and 3.68 to 3.77 ppm, while the peaks were found at 3.60 and 4.10 ppm. The identification of carbohydrates signals was possible by consulting the literature [ 15 , 18 , 25 , 26 , 27 , 28 , 29 ]. Thus, the relevant 1 H-NMR peaks obtained for the carbohydrates region are reported in Table 1 , and, for fruit juices’ classification, each signal was taken into account, this region summing a total of 38 signals.…”

“…In the same range was identified one more pair of duplets at 5.39 and 4.20 ppm, which were assigned to hydrogen in position 1 from glucose and position 2 from fructose found in the composition of a sucrose molecule. Among the investigated spectra, sucrose signals were also detected at 5.40, [15,18,[25][26][27][28][29]. Thus, the relevant 1 H-NMR peaks obtained for the carbohydrates region are reported in Table 1, and, for fruit juices' classification, each signal was taken into account, this region summing a total of 38 signals.…”

Glucose-to-Fructose Isomerization: Optimisation and Mechanistic Insights Using Cheap Polyaluminium Chloride Catalyst

“…Compared to the most popular HPLC and IC techniques [ 7 , 49 ], this protocol offers several advantages: it is non-destructive, requires minimal sample preparation, avoids dilution steps that could introduce additional uncertainties and, in contrast to Gas Chromatography, does not require any derivatization [ 50 , 51 ].…”

Análisis metabolómica del zumo de uva brasileño mediante resonancia magnética nuclear de hidrógeno

“…Por medio de éste identificamos α y β glucosa y frutosa como los principales carbohidratos presentes, a través de dobletes a 5,14 ppm para α-glucosa y 4,55 ppm para β-glucosa. Estos son isómeros diferenciados por la posición relativa del grupo hidroxilo (OH), en relación a las posiciones axiales y ecuatoriales del mismo anillopara α y ecuatorial para β, y a 4,02 ppm para la fructosa [8].…”

Classification of Prunus Genus by Botanical Origin and Harvest Year Based on Carbohydrates Profile

“…Generally, the fruit juices’ spectra are dominated by α-glucose, β-glucose, sucrose, and fructose signals, having the highest concentration among all the other metabolites. These belong to the carbohydrates region of the spectrum, which is placed in the middle-frequency region of the spectrum between 3.0 and 6.0 ppm, and it is followed by, in terms of signal intensities, amino acids, aliphatic region (from 0.5 and 3.0 ppm), and phenolic region (from 6.0 to 8.5 ppm) [ 16 , 17 , 25 , 26 , 27 , 28 , 29 ]. When the 5.40 to 4.10 ppm region was investigated, a pair of duplets were observed at 5.22 and 4.63 ppm that correspond to α and β glucose hydrogen in position 1.…”

“…Fructose signals were in the range of 3.57 to 3.60, 4.10 to 3.99 ppm, and 3.68 to 3.77 ppm, while the peaks were found at 3.60 and 4.10 ppm. The identification of carbohydrates signals was possible by consulting the literature [ 15 , 18 , 25 , 26 , 27 , 28 , 29 ]. Thus, the relevant 1 H-NMR peaks obtained for the carbohydrates region are reported in Table 1 , and, for fruit juices’ classification, each signal was taken into account, this region summing a total of 38 signals.…”

“…In the same range was identified one more pair of duplets at 5.39 and 4.20 ppm, which were assigned to hydrogen in position 1 from glucose and position 2 from fructose found in the composition of a sucrose molecule. Among the investigated spectra, sucrose signals were also detected at 5.40, [15,18,[25][26][27][28][29]. Thus, the relevant 1 H-NMR peaks obtained for the carbohydrates region are reported in Table 1, and, for fruit juices' classification, each signal was taken into account, this region summing a total of 38 signals.…”

Glucose-to-Fructose Isomerization: Optimisation and Mechanistic Insights Using Cheap Polyaluminium Chloride Catalyst

“…Compared to the most popular HPLC and IC techniques [ 7 , 49 ], this protocol offers several advantages: it is non-destructive, requires minimal sample preparation, avoids dilution steps that could introduce additional uncertainties and, in contrast to Gas Chromatography, does not require any derivatization [ 50 , 51 ].…”

Análisis metabolómica del zumo de uva brasileño mediante resonancia magnética nuclear de hidrógeno

“…Por medio de éste identificamos α y β glucosa y frutosa como los principales carbohidratos presentes, a través de dobletes a 5,14 ppm para α-glucosa y 4,55 ppm para β-glucosa. Estos son isómeros diferenciados por la posición relativa del grupo hidroxilo (OH), en relación a las posiciones axiales y ecuatoriales del mismo anillopara α y ecuatorial para β, y a 4,02 ppm para la fructosa [8].…”

Classification of Prunus Genus by Botanical Origin and Harvest Year Based on Carbohydrates Profile

“…Generally, the fruit juices’ spectra are dominated by α-glucose, β-glucose, sucrose, and fructose signals, having the highest concentration among all the other metabolites. These belong to the carbohydrates region of the spectrum, which is placed in the middle-frequency region of the spectrum between 3.0 and 6.0 ppm, and it is followed by, in terms of signal intensities, amino acids, aliphatic region (from 0.5 and 3.0 ppm), and phenolic region (from 6.0 to 8.5 ppm) [ 16 , 17 , 25 , 26 , 27 , 28 , 29 ]. When the 5.40 to 4.10 ppm region was investigated, a pair of duplets were observed at 5.22 and 4.63 ppm that correspond to α and β glucose hydrogen in position 1.…”

“…Fructose signals were in the range of 3.57 to 3.60, 4.10 to 3.99 ppm, and 3.68 to 3.77 ppm, while the peaks were found at 3.60 and 4.10 ppm. The identification of carbohydrates signals was possible by consulting the literature [ 15 , 18 , 25 , 26 , 27 , 28 , 29 ]. Thus, the relevant 1 H-NMR peaks obtained for the carbohydrates region are reported in Table 1 , and, for fruit juices’ classification, each signal was taken into account, this region summing a total of 38 signals.…”

“…In the same range was identified one more pair of duplets at 5.39 and 4.20 ppm, which were assigned to hydrogen in position 1 from glucose and position 2 from fructose found in the composition of a sucrose molecule. Among the investigated spectra, sucrose signals were also detected at 5.40, [15,18,[25][26][27][28][29]. Thus, the relevant 1 H-NMR peaks obtained for the carbohydrates region are reported in Table 1, and, for fruit juices' classification, each signal was taken into account, this region summing a total of 38 signals.…”

Glucose-to-Fructose Isomerization: Optimisation and Mechanistic Insights Using Cheap Polyaluminium Chloride Catalyst

“…Compared to the most popular HPLC and IC techniques [ 7 , 49 ], this protocol offers several advantages: it is non-destructive, requires minimal sample preparation, avoids dilution steps that could introduce additional uncertainties and, in contrast to Gas Chromatography, does not require any derivatization [ 50 , 51 ].…”

Análisis metabolómica del zumo de uva brasileño mediante resonancia magnética nuclear de hidrógeno

“…Por medio de éste identificamos α y β glucosa y frutosa como los principales carbohidratos presentes, a través de dobletes a 5,14 ppm para α-glucosa y 4,55 ppm para β-glucosa. Estos son isómeros diferenciados por la posición relativa del grupo hidroxilo (OH), en relación a las posiciones axiales y ecuatoriales del mismo anillopara α y ecuatorial para β, y a 4,02 ppm para la fructosa [8].…”