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1.
Molecules ; 26(12)2021 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-34204744

RESUMO

The cambuci is a native Brazilian fruit from the Atlantic Forest biome. A soft and astringent pulp, a green color, and a sweet aroma are its main characteristics. Classical food quality attributes (fresh fruit mass, fruit height, diameters, total soluble solid, titratable acidity, and ratio) and the metabolic profile from ten accessions from three different locations were analyzed herein by analytical methods (refractometry and neutralization titration) and nuclear magnetic resonance spectroscopy. Concerning sugar content, sucrose was the predominant compound, with glucose and fructose alternating in second, depending on the accession. Citric acid was the most relevant acid, followed by shikimic and quinic acids in quite variable amounts. These three main acids vary in amounts for each accession. Ascorbic acid content emerges as an important quality attribute and makes this fruit nutritionally attractive, due to values comparable to those contained in citric fruits. The main amino acids identified in cambuci were glutamic acid individually or in comprising the tripeptide glutathione (glutamic acid, cysteine, glycine). The quality diversity of the evaluated accessions suggests the potentiality of cambuci use in future breeding programs.


Assuntos
Frutas/química , Frutas/metabolismo , Myrtaceae/metabolismo , Ácidos/metabolismo , Antioxidantes/análise , Ácido Ascórbico/análise , Brasil , Carboidratos/análise , Qualidade dos Alimentos , Frutose/metabolismo , Glucose/metabolismo , Metaboloma , Metabolômica/métodos , Floresta Úmida
2.
Molecules ; 26(11)2021 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-34067307

RESUMO

Green pepper fruit is often consumed before it is completely ripe. However, the influence of the phenological stage in which the green pepper is consumed as a potential influencing factor in its bioactive compounds content and antioxidant capacity remains unknown. In addition, no literature is available concerning the bioactive compounds changes in 'Lamuyo' green peppers along its developmental and growth cycle. For this, two different approaches have been carried out, one using twelve different phenological stages (S1 to S12), and in the other, seven different harvest dates (from 27 February to 20 April). Moreover, bioactive compounds changes during 21 days of postharvest storage at 8 °C were investigated. In this study, bioactive compounds (ascorbic acid, dehydroascorbic acid, and total phenolic content) and the total hydrophilic and lipophilic (TAA-H and TAA-L) antioxidant activity were analysed. In addition, total soluble solids, total acidity, individual sugars, and organic acids were determined. Vitamin C levels increased along the phenological stages and harvest dates due to significant increases in ascorbic and dehydroascorbic acid levels. Our results show that the total phenol content decreases as vegetables develop and subsequently increases both as ripening begins and by the last harvest date. Furthermore, TAA-H was also greater by the phenological stage S12 and the 20 April harvest date. In conclusion, the phenological stage and harvest date are key factors that significantly influence the bioactive compounds of green peppers, and those that appear by S12 and 20 April could be more beneficial to health.


Assuntos
Antioxidantes/análise , Capsicum/química , Capsicum/crescimento & desenvolvimento , Ácido Ascórbico/análise , Ácido Ascórbico/química , Química Orgânica , Ácido Desidroascórbico/química , Análise de Alimentos , Conservação de Alimentos/métodos , Frutas/química , Concentração de Íons de Hidrogênio , Fenol , Fenóis/análise , Fenóis/química , Compostos Fitoquímicos/análise , Açúcares/química , Temperatura , Fatores de Tempo
3.
Molecules ; 26(11)2021 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-34071646

RESUMO

The use of substrates supplemented with minerals is a promising strategy for increasing the nutraceutical value of Pleurotus spp. The current research was performed to analyze the effect of substrate supplementation with magnesium (Mg) salts on the Mg content, biomass, and chemical composition of pink oyster mushroom (Pleurotus djamor) fruiting bodies. Before inoculation, substrate was supplemented with MgCl2 × 6 H2O and MgSO4, both salts were applied at three concentrations: 210, 420, and 4200 mg of Mg per 2 kg of substrate. The harvest period included three flushes. Substrate supplementation with 4200 mg of Mg caused the most significant decrease in mushroom productivity, of about 28% for both Mg salts. The dry matter content in fruiting bodies was significantly lower in the treatment in which 210 mg of Mg was applied as MgSO4 in comparison to the control. Supplementation effectively increased the Mg content in fruiting bodies of P. djamor by 19-85% depending on the treatment, and significantly affected the level of remaining bioelements and anions. One hundred grams of pink oyster fruiting bodies, supplemented with Mg salts, provides more than 20% of the Mg dietary value recommended by the Food and Drug Administration (FDA); thus, supplementation can be an effective technique for producing mushrooms that are rich in dietary Mg. Although P. djamor grown in supplemented substrate showed lower productivity, this was evident only in the fresh weight because the differences in dry weight were negligible. Mg supplementation increased the antioxidant activity of the fruiting bodies, phenolic compounds, and some amino acids, including L-tryptophan, and vitamins (thiamine and l-ascorbic acid).


Assuntos
Suplementos Nutricionais , Carpóforos/química , Magnésio/química , Pleurotus/metabolismo , Agaricales , Ácido Ascórbico/análise , Ácido Ascórbico/química , Biofortificação , Cloretos/química , Meios de Cultura , Tecnologia de Alimentos , Alimento Funcional , Fenol/química , Fenóis/química , Pleurotus/química , Sais/química , Secale/microbiologia , Açúcares/química , Sulfatos/química , Tiamina/análise , Triptofano/análise
4.
Food Chem ; 361: 130144, 2021 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-34082387

RESUMO

Effect of high-intensity ultrasound (HIU) compared with thermal treatments on baobab fruit pulp (BFP) quality and bioactive properties were investigated. HIU treatments, particularly at intensities of 687.5 W/cm2 for 5 min, and 344 W/cm2 for 15 min significantly (p < 0.05) increased the cloudiness index, ascorbic acid (AA) retention, total phenolic and flavonoid contents, and antioxidant capacity besides a more potent α-amylase and α-glucosidase inhibition relative to thermally treated samples. Moreover, the physicochemical parameters, colour index, and browning index were maintained with HIU besides lower 5-hydroxymethylfurfural values than thermal processing. HPLC analysis revealed that the content of most phenolic compounds was the highest in HIU treatments besides a 235-256% increase in procyanidin C1 compared with control samples. The AA retention following HIU treatments was 87.62-102.86% compared to 30.47-61.90% in thermally treated samples. Our analyses portrayed ultrasound as a feasible alternative to conventional thermal processing of BFP.


Assuntos
Adansonia/química , Inibidores Enzimáticos/farmacologia , Frutas/química , Ultrassom/métodos , alfa-Amilases/antagonistas & inibidores , Antioxidantes/análise , Antioxidantes/química , Ácido Ascórbico/análise , Biflavonoides/análise , Catequina/análise , Inibidores Enzimáticos/análise , Inibidores Enzimáticos/química , Flavonoides/análise , Inibidores de Glicosídeo Hidrolases/análise , Inibidores de Glicosídeo Hidrolases/química , Inibidores de Glicosídeo Hidrolases/farmacologia , Fenóis/análise , Proantocianidinas/análise , alfa-Glucosidases/metabolismo
5.
Food Chem ; 358: 129877, 2021 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-33984656

RESUMO

Rising temperature and solar radiation drive the mobilization and depletion of crown-deposited metabolites harnessed for asparagus spear regeneration during the spring harvest season. We presently examined how successive same-season harvests impact the sensory, nutritive and bioactive composition of select green asparagus genotypes. Soluble carbohydrates were analyzed by HPLC-RI, organic acids and polyphenols by HPLC-DAD and metals by ion chromatography. Higher sugars and lower acids accentuated sweetness and lower polyphenols contributed to reduced astringency at the beginning of the harvest season. This trend was reversed as the season advanced and spear sensory quality was compromised by declining sugars and rising acids; however, functional quality improved as antioxidant capacity increased along with the concentrations of quercetin-3-O-rutinoside (rutin) and ascorbic acid. The compositional changes presently described were uniform across all genotypes examined and thus contribute toward our understanding of seasonal variation in the sensory and functional quality of this acclaimed health-promoting product.


Assuntos
Asparagus (Planta)/metabolismo , Metaboloma , Agricultura/métodos , Antioxidantes/análise , Ácido Ascórbico/análise , Asparagus (Planta)/química , Asparagus (Planta)/crescimento & desenvolvimento , Carboidratos/análise , Cromatografia Líquida de Alta Pressão , Chipre , Glucosídeos/análise , Minerais/análise , Proteínas de Plantas/análise , Polifenóis/análise , Quercetina/análogos & derivados , Quercetina/análise , Metabolismo Secundário , Paladar
6.
Food Chem ; 359: 129864, 2021 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-33962194

RESUMO

Lettuce is the most consumed leafy vegetable though the most popular varieties have a low nutritional value. Our objective was to accurately quantify vitamin C and anthocyanins in wild relatives, and commercial and traditional varieties. Wild species and traditional varieties contained more total ascorbic acid (TAA) than commercial varieties (21% and 8%, respectively). In contrast, commercial varieties had significantly higher content of anthocyanins than traditional varieties and wild species (6 and 8 times more, respectively). TAA was significantly higher in green than in red lettuces (18%). TAA was also significantly higher in the leaves of two wild species than in stems. Cyanidin 3-O-(6'-O-malonylglucoside) was the most abundant anthocyanin (97%), present in most samples. The rankings of accessions by vitamin C and anthocyanin contents can be useful for consumers worried about the impacts of food on their wellbeing and for breeders aiming to improve lettuce by biofortification with health-promoting compounds.


Assuntos
Antocianinas/análise , Ácido Ascórbico/análise , Alface/química , Valor Nutritivo , Folhas de Planta/química
7.
Food Chem ; 360: 129973, 2021 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-33989878

RESUMO

The influence of recovery technique (pH-shift processing vs mechanical separation), antioxidant addition and endogenous factors on lipid oxidation in protein-enriched products from herring, salmon and cod backbones was investigated. Salmon-derived products were very stable during both ice and -20 °C storage. Contrary, peroxide value and TBA-reactive substances in herring- and cod-derived products increased rapidly during ice storage, with the pH-shift-produced protein isolates (PI) being most susceptible to oxidation in case of cod. Duralox MANC (0.5%) however largely increased the oxidation lag phase in both PI and mechanically separated meat (MSM); from <1 day to >15 days. At -20 °C, mainly the herring products oxidized, and particularly the MSM. Pearson correlation tests showed that endogenous levels of Hb, total Fe, ascorbic acid and α-tocopherol correlated significantly (p < 0.05) with lipid oxidation development. Evaluating the role of pre-processing storage indicated that fish co-products should be processed immediately after the filleting process unless antioxidants are added.


Assuntos
Antioxidantes/farmacologia , Produtos Pesqueiros/análise , Proteínas de Peixes/química , Gadiformes , Lipídeos/química , Salmão , Animais , Ácido Ascórbico/análise , Oxirredução/efeitos dos fármacos , Alimentos Marinhos/análise
8.
Food Chem ; 361: 130108, 2021 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-34038826

RESUMO

This is the first time to investigate the synergistic inactivation effect and mechanism of multifrequency ultrasound (MTUS) on A. acidoterrestris (AAT) vegetative cells and spores, nutrients and enzymes of orange juice. The optimized results of MTUS (using Box Behnken design- surface responsemethodology) and further comparison with different mode of ultrasound (mono-and multi-frequency) revealed that 20/40 kHz, 24 min and 64 °C were the best optimum results. The AAT spores and vegetative cells were inactivated by 2 and 4 logs, respectively, without deteriorating orange juice contents. In addition, AAT inactivation indicated an inversely proportional relationship with ROS production. FT-IR and UV-Vis spectroscopy characterization confirmed the existence of ROS in treated orange juice and LF-NMR analysis confirmed the inactivation of AAT spores. The findings illustrated the successfully used dual-frequency ultrasound technology for fruit beverages, promoting beneficial changes in physical properties without any significant effects on the quality of ascorbic acid.


Assuntos
Alicyclobacillus/fisiologia , Citrus sinensis/química , Sucos de Frutas e Vegetais/microbiologia , Viabilidade Microbiana , Espécies Reativas de Oxigênio/química , Sonicação , Esporos Bacterianos/fisiologia , Ácido Ascórbico/análise , Citrus sinensis/microbiologia , Microbiologia de Alimentos , Qualidade dos Alimentos , Análise Espectral , Temperatura
9.
Food Res Int ; 144: 110350, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-34053543

RESUMO

Our objective was to explore the effects of whey protein (WP) concentration and preheating temperature on anthocyanin color expression and stability over time in the presence of ascorbic acid. Anthocyanins from purple corn, grape or black carrot were mixed with native WP or preheated WP (40-80°C) in various concentrations (0-10 mg/mL) in pH 3 buffer containing 0.05% ascorbic acid and stored in the dark at 25 °C for 5 days. WP addition increased anthocyanin absorbance and protected anthocyanin from ascorbic acid-mediated degradation. Increasing WP concentration resulted in lower lightness and higher chroma, hue angle and color stability. The color loss of anthocyanin solutions decreased by 40%-50% when 10 mg/mL WP was added. Native WP showed more color enhancement and protection than thermally-induced WP. Increasing the WP preheating temperature resulted in less absorbance increase and more absorbance loss. Anthocyanin' half-life was improved by addition of WP in a dose dependent manner. Native WP addition (10 mg/mL) extended anthocyanin half-life by about 2 times for purple corn and grape, and 1.31 times for black carrot anthocyanin solutions. Preheating temperature did not significantly affect anthocyanin protection by WP. WP addition might enhance anthocyanin stability in beverages containing ascorbic acid, expanding anthocyanin application in foods.


Assuntos
Daucus carota , Vitis , Antocianinas , Ácido Ascórbico/análise , Cor , Temperatura , Proteínas do Soro do Leite , Zea mays
10.
Nutrients ; 13(4)2021 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-33923450

RESUMO

The association between metabolic syndrome and eating patterns remains unclear. We hypothesized that Korean Healthy Eating Index (KHEI) scores were related to metabolic syndrome (MetS) risk in adults in a gender-dependent manner. We aimed to examine the hypothesis using the Korea National Health and Nutrition Examination Survey-VI (2013-2017) data with a complex sample survey design. Adjusted means and 95% confidence intervals of KHEI scores and nutrient intake estimated by the 24-h recall were calculated according to MetS status after adjusting for age, residence area, region, education, obesity, income, drinking status, smoking status, marriage, and exercise. Adjusted odds ratios for MetS were measured according to KHEI quartiles using logistic regression analysis while controlling for covariates. MetS incidence was significantly higher in females than in males. Those who were older, less educated, earning less income, more obese, living in rural areas, drinking severely, non-exercising, and married had higher MetS incidence than those with the opposite state. Total KHEI scores of all components KHEI scores were lower for those with MetS (MetS group) than those without MetS (Non-MetS group) in both genders. For KHEI components, having breakfast and milk and fat intake had lower scores for the MetS group than for the Non-MetS group in women, whereas fruits and milk and milk product intake had lower scores for the MetS group in men. Nutrient intake influenced the MetS risk in females more than in males. Fat, calcium, and vitamin C intakes from 24-h recall were lower in the MetS group than in the Non-MetS group in women. KHEI scores had an inverse association with MetS risk by 0.98-fold in both genders after adjusting for covariates. In conclusion, a healthy diet that includes adequate calcium and vitamin C is associated with a lower the risk of MetS in both men and women.


Assuntos
Ácido Ascórbico/análise , Cálcio na Dieta/análise , Dieta Saudável/estatística & dados numéricos , Síndrome Metabólica/epidemiologia , Síndrome Metabólica/etiologia , Adulto , Fatores de Risco Cardiometabólico , Ingestão de Alimentos , Comportamento Alimentar , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Inquéritos Nutricionais , Razão de Chances , República da Coreia/epidemiologia , Adulto Jovem
11.
Int J Mol Sci ; 22(7)2021 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-33806141

RESUMO

The study of antioxidants and their implications in various fields, from food engineering to medicine and pharmacy, is of major interest to the scientific community. The present paper is a critical presentation of the most important tests used to determine the antioxidant activity, detection mechanism, applicability, advantages and disadvantages of these methods. Out of the tests based on the transfer of a hydrogen atom, the following were presented: the Oxygen Radical Absorption Capacity (ORAC) test, the Hydroxyl Radical Antioxidant Capacity (HORAC) test, the Total Peroxyl Radical Trapping Antioxidant Parameter (TRAP) test, and the Total Oxyradical Scavenging Capacity (TOSC) test. The tests based on the transfer of one electron include the Cupric Reducing Antioxidant Power (CUPRAC) test, the Ferric Reducing Antioxidant Power (FRAP) test, the Folin-Ciocalteu test. Mixed tests, including the transfer of both a hydrogen atom and an electron, include the 2,2'-Azinobis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) test, and the [2,2-di(4-tert-octylphenyl)-1-picrylhydrazyl] (DPPH) test. All these assays are based on chemical reactions and assessing the kinetics or reaching the equilibrium state relies on spectrophotometry, presupposing the occurrence of characteristic colours or the discolouration of the solutions to be analysed, which are processes monitored by specific wavelength adsorption. These assays were successfully applied in antioxidant analysis or the determination of the antioxidant capacity of complex samples. As a complementary method in such studies, one may use methods based on electrochemical (bio)sensors, requiring stages of calibration and validation. The use of chemical methods together with electrochemical methods may result in clarification of the operating mechanisms and kinetics of the processes involving several antioxidants.


Assuntos
Antioxidantes/farmacologia , Ácido Ascórbico/análise , Sequestradores de Radicais Livres/farmacologia , Radical Hidroxila/farmacologia , Animais , Benzotiazóis/química , Bioensaio/métodos , Compostos de Bifenilo , Técnicas Eletroquímicas , Humanos , Hidrogênio/química , Cinética , Oxigênio/química , Fenóis/análise , Picratos , Espécies Reativas de Oxigênio/metabolismo , Ácidos Sulfônicos/química , Superóxido Dismutase/metabolismo
12.
Molecules ; 26(9)2021 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-33924795

RESUMO

The aim of the present study was to determine the influence of the winemaking process on the antioxidant potential and content of phenolic compounds and L-ascorbic acid in wines from the fruits of Rosa rugosa. The results obtained in this study clearly indicate that the fruits of the Rosa rugosa are a desirable raw material for the production of fruit wine. The parameters of the technological process of producing wines from rose fruits had a diversified influence on the tested quality characteristics. Aged wines contained phenolics levels of 473-958 mg/100 mL GAE. The final concentrations of ascorbic acid ranged from 61 to 155 mg/100 mL for the different variants of the wine. Wines revealed high antioxidant activity in assay with DPPH. On the basis of the obtained results, it can be assumed that all the applied variants of the winemaking process are suitable for rose fruit wine. Each variant ensured at least the stability of the antioxidant capacity.


Assuntos
Antioxidantes/farmacologia , Ácido Ascórbico/farmacologia , Frutas/química , Polifenóis/farmacologia , Rosa/química , Vinho/análise , Antioxidantes/análise , Antioxidantes/química , Ácido Ascórbico/análise , Ácido Ascórbico/química , Fenômenos Químicos , Fermentação , Sequestradores de Radicais Livres/análise , Sequestradores de Radicais Livres/química , Sequestradores de Radicais Livres/farmacologia , Compostos Fitoquímicos/química , Compostos Fitoquímicos/farmacologia , Polifenóis/análise , Polifenóis/química
13.
Nutrients ; 13(3)2021 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-33805588

RESUMO

Our aim was to study the associations between maternal vitamin C and iron intake during pregnancy and the offspring's risk of developing islet autoimmunity and type 1 diabetes. The study was a part of the Finnish Type 1 Diabetes Prediction and Prevention (DIPP) prospective birth cohort including children genetically at risk of type 1 diabetes born between 1997-2004. The diets of 4879 mothers in late pregnancy were assessed with a validated food frequency questionnaire. The outcomes were islet autoimmunity and type 1 diabetes. Cox proportional hazards regression analysis adjusted for energy, family history of diabetes, human leukocyte antigen (HLA) genotype and sex was used for statistical analyses. Total intake of vitamin C or iron from food and supplements was not associated with the risk of islet autoimmunity (vitamin C: HR 0.91: 95% CI (0.80, 1.03), iron: 0.98 (0.87, 1.10)) or type 1 diabetes (vitamin C: 1.01 (0.87, 1.17), iron: 0.92 (0.78, 1.08)), neither was the use of vitamin C or iron supplements associated with the outcomes. In conclusion, no association was found between maternal vitamin C or iron intake during pregnancy and the risk of islet autoimmunity or type 1 diabetes in the offspring.


Assuntos
Doenças Autoimunes/imunologia , Diabetes Mellitus Tipo 1/imunologia , Dieta/efeitos adversos , Exposição Materna/efeitos adversos , Fenômenos Fisiológicos da Nutrição Materna/imunologia , Efeitos Tardios da Exposição Pré-Natal/imunologia , Adulto , Ácido Ascórbico/análise , Doenças Autoimunes/genética , Pré-Escolar , Diabetes Mellitus Tipo 1/genética , Dieta/estatística & dados numéricos , Inquéritos sobre Dietas , Suplementos Nutricionais , Feminino , Finlândia , Genótipo , Antígenos HLA/imunologia , Humanos , Lactente , Ferro na Dieta/análise , Ilhotas Pancreáticas/imunologia , Masculino , Gravidez , Efeitos Tardios da Exposição Pré-Natal/genética , Modelos de Riscos Proporcionais , Estudos Prospectivos , Análise de Regressão
14.
Molecules ; 26(4)2021 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-33672083

RESUMO

Sweet pepper is one of the most important economic fruits with nutritional attributes. In this sense, the nutraceutical value of consumed products is a major concern nowadays so the content of some bioactive compounds and antioxidants (phenols, ascorbic acid, lycopene, carotenoids, chlorophylls, and antioxidant activity) was monitored in 18 sweet pepper landraces at two maturity stages (green and red). All the traits except chlorophylls significantly increased in red fruits (between 1.5- and 2.3-fold for phenols, ascorbic acid, and 2-2-diphenyl-1-picrylhydrazyl (DPPH) inhibition activity, 4.8-fold for carotenoid and 27.4-fold for lycopene content), which suggests that ripening is key for obtaining desired fruit quality. Among landraces, P-44 in green fruits is highlighted for its content in carotenoids, chlorophylls, phenols, and ascorbic acid, and P-46 for its antioxidant capacity and lycopene content. Upon maturity, P-48, P-44, and P-41 presented higher levels of phenols and lycopene, and P-39 of phenols, carotenoid, and DPPH. This work reflects a wide variability in the 18 pepper landraces at bioactive compounds concentration and in relation to fruit ripeness. The importance of traditional landraces in terms of organoleptic properties is emphasized as they are the main source of agricultural biodiversity today and could be helpful for breeders to develop new functional pepper varieties.


Assuntos
Antioxidantes/farmacologia , Capsicum/química , Ecótipo , Compostos Fitoquímicos/farmacologia , Ácido Ascórbico/análise , Clorofila/análise , Suplementos Nutricionais/análise , Frutas/química , Licopeno/análise , Fenóis/análise , Pigmentação , Análise de Componente Principal
15.
Molecules ; 26(5)2021 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-33669142

RESUMO

Water-soluble fluorescent carbon dots (CDs) were synthesized by a hydrothermal method using citric acid as the carbon source and ethylenediamine as the nitrogen source. The repeated and scale-up synthetic experiments were carried out to explore the feasibility of macroscopic preparation of CDs. The CDs/Fe3+ composite was prepared by the interaction of the CDs solution and Fe3+ solution. The optical properties, pH dependence and stability behavior of CDs or the CDs/Fe3+ composite were studied by ultraviolet spectroscopy and fluorescence spectroscopy. Following the principles of fluorescence quenching after the addition of Fe3+ and then the fluorescence recovery after the addition of asorbic acid, the fluorescence intensity of the carbon dots was measured at λex = 360 nm, λem = 460 nm. The content of ascorbic acid was calculated by quantitative analysis of the changing fluorescence intensity. The CDs/Fe3+ composite was applied to the determination of different active molecules, and it was found that the composite had specific recognition of ascorbic acid and showed an excellent linear relationship in 5.0-350.0 µmol·L-1. Moreover, the detection limit was 3.11 µmol·L-1. Satisfactory results were achieved when the method was applied to the ascorbic acid determination in jujube fruit. The fluorescent carbon dots composites prepared in this study may have broad application prospects in a rapid, sensitive and trace determination of ascorbic acid content during food processing.


Assuntos
Ácido Ascórbico/análise , Carbono/química , Corantes Fluorescentes/química , Pontos Quânticos/química , Corantes Fluorescentes/síntese química , Frutas/química , Ziziphus/química
16.
Clin Biochem ; 92: 71-76, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33766514

RESUMO

Owing to their ease of use, glucose meters are frequently used in research and medicine. However, little is known of whether other non-glucose molecules, besides vitamin C, interfere with glucometry. Therefore, we sought to determine whether other antioxidants might behave like vitamin C in causing falsely elevated blood glucose levels, potentially exposing patients to glycemic mismanagement by being administered harmful doses of glucose-lowering drugs. To determine whether various antioxidants can be detected by seven commercial glucose meters, human blood samples were spiked with various antioxidants ex vivo and their effect on the glucose results were assessed by Parkes error grid analysis. Several of the glucose meters demonstrated a positive bias in the glucose measurement of blood samples spiked with vitamin C, N-acetylcysteine, and glutathione. With the most interference-sensitive glucose meter, non-blood solutions of 1 mmol/L N-acetylcysteine, glutathione, cysteine, vitamin C, dihydrolipoate, and dithiothreitol mimicked the results seen on that glucose meter for 0.7, 1.0, 1.2, 2.6, 3.7 and 5.5 mmol/L glucose solutions, respectively. Glucose meter users should be alerted that some of these devices might produce spurious glucose results not only in patients on vitamin C therapy but also in those being administered other antioxidants. As discussed herein, the clinical relevance of the data is immediate in view of the current use of antioxidant therapies for disorders such as the metabolic syndrome, diabetes, cardiovascular diseases, and coronavirus disease 2019.


Assuntos
Antioxidantes/química , Automonitorização da Glicemia/instrumentação , Glicemia/análise , Acetilcisteína/sangue , Acetilcisteína/química , Antioxidantes/análise , Antioxidantes/metabolismo , Ácido Ascórbico/análise , Ácido Ascórbico/sangue , Glicemia/química , Automonitorização da Glicemia/métodos , Glutationa/sangue , Glutationa/química , Humanos , Sistemas Automatizados de Assistência Junto ao Leito
17.
Food Chem ; 354: 129503, 2021 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-33743446

RESUMO

As a flavor and quality parameter, furfural has potential undesirable effects. This study aimed to elucidate furfural formation, including generation, pathways, and possible precursors during the production of Zhenjiang aromatic vinegar. A cereal vinegar model, rich in saccharides, amino acids, and organic acids, was used to explore the potential precursors. Furfural and 5-hydroxymethylfurfural (HMF) mainly generated during the decoction process, but the HMF also increased during the aging process. Three pathways were found to coexist for the formation of furfural: (i) the Maillard reaction induced by saccharides and nitrogenous compounds, (ii) the direct cleavage of pentose, and (iii) indirect conversion from pentosan, which only made a minor contribution. Furfural was not formed from HMF or l-ascorbic acid in vinegar. Instead, ribose, xylose, arabinose, galacturonic acid, glucuronic acid, and pentosan were the main precursors. These insights may be useful for the risk/benefit balance and improve the flavor quality and safety.


Assuntos
Ácido Acético/análise , Furaldeído/análise , Aminoácidos/análise , Ácido Ascórbico/análise , Cromatografia Líquida de Alta Pressão/métodos , Furaldeído/análogos & derivados , Furaldeído/química , Espectrofotometria Ultravioleta , Açúcares/análise , Ácidos Urônicos/análise
18.
Food Chem ; 354: 129491, 2021 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-33756330

RESUMO

The study was aimed to evaluate if deetiolation of barley and wheat microgreens after cultivaton in dark (for 5, 7 and 9 days) can enhance the contents of pigments, ascorbic acid, polyphenols, and equivalent antioxidant capacities (EAC) (measured by DPPH and FRAP assay) in correlation to other. Chlorophylls and carotenoids were higher in microgreens that were exposed more to daylight. In contrast, ascorbic acid, polyphenols and EAC of microgreens could be enhanced by 5-7 days of etiolation. However, prolonged etiolation reduced overall antioxidant capacities of microgreens. All evaluated parameters could be satisfactorily represented by regression expressions for the given number of days of etiolation and growth. The ascorbic acid and total carotenoids content had higher correlations with total chlorophyll contents, while the antioxidant capacities were highly correlated to total polyphenols content. The study confirms the potential of deetiolated cultivation of microgreens to enhance selective phytochemicals content and EAC of microgreens.


Assuntos
Antioxidantes/química , Ácido Ascórbico/análise , Carotenoides/análise , Clorofila/análise , Hordeum/química , Polifenóis/análise , Triticum/química , Hordeum/metabolismo , Extratos Vegetais/química , Espectrofotometria , Temperatura , Triticum/metabolismo
19.
Artigo em Inglês | MEDLINE | ID: mdl-33690092

RESUMO

Ascorbic acid (AA) and uric acid (UA) are known as two of the major antioxidants in biological fluids. We report a novel liquid chromatography-mass spectrometry with time-of-flight (LC-MS-TOF) method for the simultaneous quantification of ascorbic and uric acids using MPA, antioxidant solution and acetonitrile as a protein precipitating agent. Both compounds were separated from interferences using a reverse phase C18 column with water and acetonitrile gradient elution (both with formic acid) and identified and quantified by MS in the negative ESI mode. Isotope labeled internal standards were also added to ensure the accuracy of the measures. The method was validated for exhaled breath condensate (EBC), nasal lavage (NL) and plasma samples by assessing selectivity, linearity, accuracy and precision, recovery and matrix effect and stability. Sample volumes below 250 µL were used and linear ranges were determined between 1 - 25 and 1 - 40 µg/mL for ascorbic and uric acid, respectively, for plasma samples, and between 0.05 - 5 (AA) and 0.05 - 7.5 (UA) µg/mL for EBC and NL samples. The new method was successfully applied to real samples from subjects that provided each of the studied matrices. Results showed higher amounts determined in plasma samples, with similar profiles for AA and UA in EBC and NL but at much lower concentrations.


Assuntos
Ácido Ascórbico/análise , Cromatografia Líquida de Alta Pressão/métodos , Espectrometria de Massas/métodos , Ácido Úrico/análise , Adolescente , Adulto , Testes Respiratórios , Feminino , Humanos , Modelos Lineares , Masculino , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Adulto Jovem
20.
Food Res Int ; 140: 110062, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33648285

RESUMO

For the first time, a model system approach was combined with 1H NMR fingerprinting in studying non-enzymatic browning (NEB) of pasteurized shelf-stable orange juice during storage. Various NEB precursors were used individually or in combinations to formulate simple or complex model systems, respectively, in citric acid buffer. Based on orange juice composition, ascorbic acid, sugars (sucrose, glucose and fructose) and amino acids (proline, arginine, asparagine, aspartic acid, serine and glutamic acid) were selected as the precursors for the model systems. After pasteurization and during subsequent accelerated storage (42 °C, 16 weeks) the model systems displayed a three-phase browning development. The initial browning phase was mainly the result of ascorbic acid degradation especially in the presence of amino acids and sugars. In the later phases, the contribution of reactions of sugars and amino acids to browning became apparent. The application of 1H NMR fingerprinting on a simple model system containing ascorbic acid revealed that its degradation pathway to intermediates such as xylonic acid, acetic acid and erythrulose was responsible for the major changes during storage. When this model system was complexed by inclusion of sugars and amino acids, the hydrolysis of sucrose to glucose and fructose was identified as the main reaction leading to differences in the samples throughout storage. These three sugars dominated the NMR spectra of the samples, overshadowing several important compounds for NEB such as ascorbic acid and its degradation products. Other more advanced NMR experiments such as two-dimensional NMR analyses should be applied in future research to identify unknown compounds from NEB reactions.


Assuntos
Citrus sinensis , Ácido Ascórbico/análise , Sucos de Frutas e Vegetais , Pasteurização , Espectroscopia de Prótons por Ressonância Magnética
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