scholarly journals Functionalization of Screen-Printed Sensors with A High Reactivity Carbonaceous Material for Ascorbic Acid Detection in Fresh-Cut Fruit with Low Vitamin C Content

Chemosensors ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 354
Author(s):  
Ylenia Spissu ◽  
Antonio Barberis ◽  
Gianfranco Bazzu ◽  
Guy D’hallewin ◽  
Gaia Rocchitta ◽  
...  
Keyword(s):  
Ascorbic Acid ◽  
Vitamin C ◽  
Carbonaceous Material ◽  
High Reactivity ◽  
Multi Walled Carbon Nanotubes ◽  
Printed Sensors ◽  
Constant Potential ◽  
Fresh Cut ◽  
Ascorbic Acid Detection ◽  
Screen Printed

In this study, carbon screen-printed sensors (C-SPEs) were functionalized with a high reactivity carbonaceous material (HRCM) to measure the ascorbic acid (AA) concentration in fresh-cut fruit (i.e., watermelon and apple) with a low content of vitamin C. HRCM and the functionalized working electrodes (WEs) were characterized by SEM and TEM. The increases in the electroactive area and in the diffusion of AA molecules towards the WE surface were evaluated by cyclic voltammetry (CV) and chronoamperometry. The performance of HRCM-SPEs were evaluated by CV and constant potential amperometry compared with the non-functionalized C-SPEs and MW-SPEs nanostructured with multi-walled carbon nanotubes. The results indicated that SPEs functionalized with 5 mg/mL of HRCM and 10 mg/mL of MWCNTs had the best performances. HRCM and MWCNTs increased the electroactive area by 1.2 and 1.4 times, respectively, whereas, after functionalization, the AA diffusion rate towards the electrode surface increased by an order of 10. The calibration slopes of HRCM and MWCNTs improved from 1.9 to 3.7 times, thus reducing the LOD of C-SPE from 0.55 to 0.15 and 0.28 μM, respectively. Finally, the functionalization of the SPEs proved to be indispensable for determining the AA concentration in the watermelon and apple samples.

scholarly journals Functional Quality and Colour Attributes of Two High-Lycopene Tomato Breeding Lines Grown under Greenhouse Conditions

2016 ◽  
Vol 4 (5) ◽  
pp. 365 ◽  
Author(s):  
Ilahy Riadh ◽  
Siddiqui Mohammed Wasim ◽  
Tlili Imen ◽  
Piro Gabriela ◽  
Lenucci Marcello Salvatore ◽  
...  
Keyword(s):  
Ascorbic Acid ◽  
Vitamin C ◽  
Antioxidant Activities ◽  
Rio Grande ◽  
Total Vitamin ◽  
Total Carotenoids ◽  
Breeding Lines ◽  
Functional Quality ◽  
Fresh Cut ◽  
Β Carotene

This study investigates the antioxidant components (total carotenoids, lycopene, β-carotene, total phenols, flavonoids, ascorbic acid and total vitamin C) as well as the hydrophilic and lipophilic antioxidant activities (HAA and LAA) of tomato genotypes consisting of one ordinary cultivar Rio Grande and the two high-lycopene breeding lines HLT-F71 and HLT-F72. The correlation of nutritional value to L∗, a∗, b∗ colour indexes and a∗/b∗ ratio was also investigated in whole and fresh cut tomato fruits. Except for β-carotene content, significant differences were found among cultivars for antioxidants. The berries of both HLT-lines recorded higher antioxidant contents, HAA and LAA (TEAC and FRAP assays) than Rio Grande. Under controlled conditions, HLT-F72 reached the highest levels of total carotenoids (165.5 mg β-ca Eq per kg fw), lycopene (150.1 mg per kg fw) and total phenolics (549.7 mg GAE per kg fw). However, HLT-F72 exhibited the highest levels of ascorbic acid (193.3 mg per kg fw), total vitamin C (271.6 mg per kg fw) and flavonoids (450.5 mg RE per kg fw). Line HLT-F71 showed the highest HAA (148.0 µM Trolox per 100 g fw and 4.2 mM FRAP per g fw) and LAA values (258.5 µM Trolox per 100 g fw and 3.2 mM FRAP per g fw respectively). Colour readings in red ripe fresh cut tomato berries particularly a∗, b∗ and the ratio a∗/b∗ could represent an indicator not only for lycopene but also for other phytochemicals and resulting antioxidant activities. HLT-Lines may serve as a starting point for the development of semi-determinate growth habit tomato cultivars with higher functional quality.

Nanobiocomposite-Based Bienzyme Screen-Printed Electrode for Glucose Monitoring

2012 ◽  
Vol 452-453 ◽  
pp. 909-912
Author(s):  
Saithip Pakapongpan ◽  
Surachai Thachepan ◽  
Yingyot Poo-Arporn ◽  
Rungtiva Palangsuntikul
Keyword(s):  
Carbon Nanotubes ◽  
Methylene Blue ◽  
Ascorbic Acid ◽  
Cyclic Voltammetry ◽  
Limit Of Detection ◽  
Glucose Monitoring ◽  
Screen Printed Electrode ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes ◽  
Screen Printed

Multi-walled carbon nanotubes (MWNTs) were coated first with methylene blue (MB) by noncovalent adsorption and then by horseradish peroxidase (HRP) and glucose oxidase (GOD) by covalent-linking. The MB-MWNTs/GOD/HRP composites formed stable films on screen-printed electrodes (SPE). The electrochemical and electrocatalytic behaviors of the bienzyme modified SPE were studied using cyclic voltammetry (CV) and amperometry. Using the MB-MWNT/GOD/HRP composites, glucose could be calibrated by amperometry at −0.35 V vs. SCE. The optimized response (at pH 7.0) had a sensitivity of 2.4 mA.M−1 and a limit of detection (3×S/N) of 35 µM. Tests of the portable bienzyme sensor demonstrate its imperviousness to the effects of ascorbic acid, uric acid and p-acetaminophen, as well as its ability to measure glucose concentrations ranging from 0.25 to 2 mM.

scholarly journals A Storage-Dependent Platinum Functionalization with a Commercial Pre-Polymer Useful for Hydrogen Peroxide and Ascorbic Acid Detection

Sensors ◽  
2019 ◽  
Vol 19 (11) ◽  
pp. 2435 ◽  
Author(s):  
Patrizia Monti ◽  
Quirico Migheli ◽  
Andrea R. Bartiromo ◽  
Antonio Pauciulo ◽  
Rocco Gliubizzi ◽  
...  
Keyword(s):  
Ascorbic Acid ◽  
Storage Conditions ◽  
Conductive Layer ◽  
Preliminary Assessment ◽  
Pt Electrode ◽  
Constant Potential ◽  
H2o2 Oxidation ◽  
Electroactive Species ◽  
Ascorbic Acid Detection ◽  
Substantial Change

A preliminary assessment of properties of the commercial product Chemiplus 2DS HB (BI-QEM Specialties SpA) is proposed. Cyclic voltammetry of this oligomer containing sulfate/sulfone groups shows a single oxidative peak at +0.866 V vs. Ag/AgCl, and its passivating process on Pt electrode suggests the formation of a non-conductive layer. Electrode modification was achieved by exploiting the constant potential amperometry setting potential at +0.900 V vs. Ag/AgCl. A substantial change in the oxidative currents from electroactive species H2O2 and ascorbic acid (AA) were observed on Pt/Chemiplus 2DS HB sensors compared to unmodified Pt. Furthermore, the influence of different storage conditions on modified sensors was examined. A storage solution containing AA concentration from 0.1 until 10 mM maintained effective AA rejection of Pt/Chemiplus 2DS HB after 7 days from construction; H2O2 oxidation capability was also retained. Sulfone and sulfonate groups of Chemiplus 2DS HB are likely responsible for the dimensionality of the film and the electrostatic interaction leading to a self-blocking/self-rejection of AA. The way Pt/Chemiplus can reveal the AA presence depends on the maintaining of AA rejection, and this peculiarity can distinguish it from other sensors or biosensors.

Continuous determination of phenol, vitamin C, lysine and glucose in flowing solutions by means of an amperometric enzyme electrode

1981 ◽  
Vol 46 (11) ◽  
pp. 2871-2876 ◽  
Author(s):  
Lumír Macholán ◽  
Petr Londýn ◽  
Jiří Fischer
Keyword(s):  
Ascorbic Acid ◽  
Vitamin C ◽  
Flow Rate ◽  
Linear Relation ◽  
Substrate Concentration ◽  
Area Under The Curve ◽  
Constant Potential ◽  
Amperometric Enzyme Electrode ◽  
Continuous Determination

A model apparatus is described for the continuous determination of compounds susceptible to catalytic oxidation by enzymes attached chemically to a membrane covering Clark's oxygen cell. The substrate concentration is estimated indirectly from the consumption of oxygen, which is proportional to the area under the curve registered at a constant potential of -0.65 V. A linear relation was found for phenol, ascorbic acid, L-lysine, glucose and polyamines. It is possible to analyze 15-30 samples in 1 h, depending on the flow rate of the carrier buffer.

scholarly journals Developing a Value-added Fresh-cut `D'Anjou' Pear Product

2003 ◽  
Vol 13 (2) ◽  
pp. 314-320 ◽  
Author(s):  
Paul M. Chen ◽  
Diane M. Varga ◽  
Clark F. Seavert
Keyword(s):  
Ascorbic Acid ◽  
Vitamin C ◽  
Value Added ◽  
Transparent Plastic ◽  
Plastic Container ◽  
A Value ◽  
Fresh Cut ◽  
Cut Surface ◽  
Prototype Design ◽  
Dipping Time

We have established that `d'Anjou' pears (Pyrus communis) are properly ripened for fresh-cut use when flesh firmness (FF) is between 5 lb (2.3 kg) and 7 lb (3.2 kg). In this study, the fruit was ripened in air enriched with 100 ppm (mL·L-1) ethylene at 68 °F (20.0 °C). Afterward, we investigated three slicing methods, each employing a fruit sectionizer for dividing individual pears into eight wedges. The easiest and most convenient cutting procedure involved pouring an antibrowning agent onto the incision, but without allowing the fruit to directly contact the air. We evaluated various combinations of L-ascorbic acid (vitamin C) and potassium chloride (KCl) for their ability to prevent any discoloration while also not affecting taste or injuring the cut surface. The most suitable antibrowning solution contained 10% L-ascorbic acid and 2% KCl (pH 2.3). A dipping time of 30 s was sufficient for maintaining the wedges with little discoloration over a 14-d period, at either 30 or 35 °F (-1.1 or 1.7 °C). Here, we also present a prototype design for a 1.6-pt (0.76-L) transparent plastic container with eight compartments for holding wedges sliced with a commercially available sectionizer.

Amperometric assay of vitamin C using an ascorbate oxidase enzyme electrode

1979 ◽  
Vol 44 (11) ◽  
pp. 3395-3404 ◽  
Author(s):  
Pavel Posádka ◽  
Lumír Macholán
Keyword(s):  
Ascorbic Acid ◽  
Vitamin C ◽  
Oxygen Electrode ◽  
Ascorbate Oxidase ◽  
Current Response ◽  
Reaction Conditions ◽  
Long Term Storage ◽  
Oxidase Enzyme ◽  
Optimal Reaction

An oxygen electrode of the Clark type, coated by a thin, active layer of chemically insolubilized ascorbate oxidase from squash peelings specifically detects by measuring oxygen uptake 10 to 400 μg of ascorbic acid in 3 ml of phosphate buffer. The record of current response to substrate addition lasts 1-2 min. The ascorbic acid values determined in various samples of fruit juices are in good agreement with the data obtained by titration and polarography. The suitable composition of the membrane and its lifetime and stability during long-term storage are described; optimal reaction conditions of vitamin C determination and the possibilities of interference of other compounds are also examined. Of the 35 phenols, aromatic amines and acids tested chlorogenic acid only can cause a positive error provided that the enzyme membrane has been prepared from ascorbate oxidase of high purity.

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