A screening method for the determination of ascorbic acid in fruit juices and soft drinks

SNaP-C: Validation of a novel, selective silver nanoparticle antioxidant capacity assay for Vitamin C content in beverages

A validated silver nanoparticle assay (SNaP-C) for quantitation of Vitamin C, as ascorbic acid (AA) and total AA (TAA), was applied to 31 beverages. SNaP-C assay results (LOD of 2.2 mg/L AA) were compared to AA and TAA determined by high-performance liquid chromatography with UV/Vis (LOD = 0.4 mg/L AA), and two well-known assays. All approaches were calibrated using meta-phosphoric acid stabilized AA, where the reducing agent tris(2-carboxyethyl) phosphine hydrochloride was added to convert dehydroascorbic acid to AA for determination of TAA. Statistical comparisons of these four resulting datasets were completed. SNaP-C and HPLC were not statistically significantly different (P > 0.05) for comparison of AA and TAA (mg/L) in these samples, whereas the CUPRAC and Folin-Ciocalteu assays statistically significantly overestimated values of AA and TAA content, respectively. The SNaP-C method is a novel assay that has high specificity for AA capable of quantifying TAA with addition of TCEP.

Evaluation of total phenols content, anti-DPPH activity and the content of selected antioxidants in the honeybee drone brood homogenate

The subject of the present research is the evaluation of health-promoting properties caused by the presence of some vitamins as well as the antioxidative potential of the honeybee drone brood homogenate (DBH). The study used 139 homogenate samples obtained from various apiaries and collected over 3 years, three times during each beekeeping season. Samples differed in terms of varroa infestation, stage of brood development, location of the apiary, and the degree of environmental contamination. The content of ascorbic acid, α-tocopherol, all-trans-retinol, and coenzyme Q₁₀ in the tested samples was determined through the application of HPLC/DAD/UV and LC/QQQ/MS methods. The antioxidant potential of samples was assessed using the Folin-Ciocalteu and DPPH methods.

Recent Techniques in Nutrient Analysis for Food Composition Database

Food composition database (FCD) provides the nutritional composition of foods. Reliable and up-to date FCD is important in many aspects of nutrition, dietetics, health, food science, biodiversity, plant breeding, food industry, trade and food regulation. FCD has been used extensively in nutrition labelling, nutritional analysis, research, regulation, national food and nutrition policy. The choice of method for the analysis of samples for FCD often depends on detection capability, along with ease of use, speed of analysis and low cost. Sample preparation is the most critical stage in analytical method development. Samples can be prepared using numerous techniques; however it should be applicable for a wide range of analytes and sample matrices. There are quite a number of significant improvements on sample preparation techniques in various food matrices for specific analytes highlighted in the literatures. Improvements on the technology used for the analysis of samples by specific instrumentation could provide an alternative to the analyst to choose for their laboratory requirement. This review provides the reader with an overview of recent techniques that can be used for sample preparation and instrumentation for food analysis which can provide wide options to the analysts in providing data to their FCD.

Biofertilizers with beneficial rhizobacteria improved plant growth and yield in chili (Capsicum annuum L.)

Chemical fertilizers can supply essential nutrients to crops increasing their yield, however, they can also cause serious environmental problems. Biofertilizer has received more and more attention because of its environmentally friendly and pollution-free characteristics. Haloxylon ammodendron, a desert succulent shrub, has become an important plant species for vegetation restoration in several deserts in China because of its strong drought tolerance. Its extensive root systems and unique rhizosphere bacterial community aid H. ammodendron adapt to this extreme environment. In this study, Bacillus sp. WM13-24 and Pseudomonas sp. M30-35 isolated from the rhizosphere of H. ammodendron in our previous study and Bacillus amyloliquefaciens GB03 and Sinorhizobium meliloti ACCC17578 as well-studied beneficial strains were used to prepare two types of biofertilizer, WM13-24 biofertilizer containing Bacillus sp. WM13-24 and integrated biofertilizer containing all the four strains. Results presented here showed that WM13-24 biofertilizer and the integrated biofertilizer improved chili plant growth, fruit yield and quality and the rhizosphere soil nitrogen content, enzyme activities, and the quantity and biodiversity of viable bacteria. Compared to the control, WM13-24 biofertilizer and a commercial biofertilizer, the integrated biofertilizer performed best in significantly increasing plant height, stem diameter, leaf length and width, chlorophyll content, fruit yield, soluble sugar content, ascorbic acid content, organic acid content, soil urease activity, catalase activity and the quantity and biodiversity of viable bacteria. This study provided a theoretical and practical basis for large scale development of integrated biofertilizers using beneficial rhizobacterial strains from the desert plant rhizosphere.

Multiplexed Paper Microfluidics for Titration and Detection of Ingredients in Beverages

Food safety and access to systematic approaches for ensuring detection of food hazards is an important issue in most developing countries. With the arrival of paper-based analytical devices (µPADs) as a promising, rapid, easy-to-use, and low-cost analytical tool, we demonstrated a simple microfluidic-based titration study for the analysis of packaged fruit juices. Similar, to the titration experiments using traditional glassware in chemistry laboratories, in this study the titration experiments were developed using paper microfluidics for the analysis of several analytes such as pH, vitamin C, sugars, and preservatives present in the packaged fruit juices. The allergen found commonly in dairy based mixtures and the non-pathogenic biochemical component responsible for food spoilage in cider based fruit juices were also determined. The results obtained using paper microfluidics were compared with those obtained using a conventional spectrophotometric technique. Finally, a paper microfluidics based multiplexed sensor was developed for the analysis of common nutritional ingredients, an allergen, and a non-pathogenic byproduct present in packaged fruit juices on a single platform. Overall, the results presented in this study reveal that the proposed paper microfluidic assisted colorimetric multiplexed sensor offers a quick and reliable tool for on-spot routine analysis for food safety applications.

Contribution of Blood Orange-Based Beverages to Bioactive Compounds Intake

The study aimed at screening the levels of ascorbic acid, hydroxycinnamic acids (HCAs) and total anthocyanins in commercial beverages containing blood orange juice (BOJ), estimating the contribution of these products to the intake of health-promoting compounds and at discussing the actual value of the products on a price/bioactive level basis. Results demonstrate that the reference to BOJ in many beverages is misleading, as inferred from the very low bioactive levels observed. These beverages, in label should refer as “water-based” instead of “fruit-based beverage.” Accordingly, the intake of bioactives from BOJ-based beverages, with the exception of ascorbic acid used in the most cases as preservative, is often very low. The intake of bioactive components from blood orange consumption is much higher compared to the consumption of BOJ-based beverages, hence the consumption of blood oranges and 100% BOJs should be preferred in order to guarantee the intake of a rich pool of bioactive compounds. Finally, the market value of BOJ-based beverages is not correlated with their real nutritional value: the relative unitary cost of the three classes of bioactive compounds considered increased in the order: fresh blood oranges < 100% BOJ < BOJ-based beverages. Hence, the consumption of fresh blood oranges represents the cheapest way to ensure the intake of health-promoting bioactive compounds such as anthocyanins and HCAs.

Comparison between titrimetric and spectrophotometric methods for quantification of vitamin C

Vitamin C is usually quantified by titrimetric or chromatographic methods. However, these methods have limitations: food color interferes with the titrimetric method and the chromatographic method is costly. The aim of this study was to compare a spectrophotometric method, based on reduction of cupric ions in the presence of cuproine complex, with a titrimetric method, based on reduction of 2,6-dicholorophenolindophenol. Linearity, precision, accuracy, and limits of detection (LOD) and quantification (LOQ) were evaluated using a standard vitamin C solution. Both methods were also applied for AA quantification in industrialized orange and pineapple juices. The methods were precise and accurate when applied to the standard solution. The spectrophotometric method was more sensitive, with lower values for LOD (0.002mgmL^-1) and LOQ (0.010mgmL^-1), and more accurate with error less than 5% while results from the titrimetric method were affected by the juice color, which generated errors in excess of 15%.

Methyl-inositol, γ-aminobutyric acid and other health benefit compounds in the aril of litchi

The available components in the flesh of litchi seem insufficient to interpret its wide and significant physiological effects. Some unusual compounds, including myo-inositol, inositol methyl derivatives and γ-aminobutyric acid (GABA) were identified as main constituents in the flesh of litchi. Their concentrations varied among cultivars but remain relatively constant during development. Litchi flesh was shown to contain moderate myo-inositol (0.28-0.78 mg g(-1) FW), ascorbic acid (0.08-0.39 mg g(-1) FW) and phenolics (0.47-1.60 mg g(-1) FW), but abundant l-quebrachitol (1.6-6.4 mg g(-1) FW) and GABA (1.7-3.5 mg g(-1) FW). The concentration of GABA in the flesh of litchi was about 100 times higher than in other fruits. And l-quebrachitol is not a common component in fruits. The biological and physiological activities of inositols, inositol derivatives and GABA have been extensively documented. These compounds are probably important compositional characteristic contributing to the widely shown health benefits of litchi.

Mineral Composition and Nutritive Value of Isotonic and Energy Drinks

Several very popular brands of isotonic and energy drinks consumed for fluid and electrolyte supplementation and stimulation of mental or physical alertness were chosen for investigation. Liquid beverages available in polyethylene bottles and aluminum cans as well as products in the form of tablets and powder in sachets were studied. The total concentrations of 21 elements (Ag, Al, B, Ba, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Mo, Na, Ni, P, Pb, Sr, Ti, V, and Zn), both essential and toxic, were simultaneously determined in preconcentrated drink samples by inductively coupled plasma-optical emission spectrometry (ICP-OES) equipped with pneumatic and ultrasonic nebulizers. Differences between the mineral compositions of isotonic and energy drinks were evaluated and discussed. The highest content of Na was found in both isotonic and energy drinks, whereas quite high concentrations of Mg were found in isotonic drinks, and the highest amount of calcium was quantified in energy drinks. The concentrations of B, Co, Cu, Ni, and P were higher in isotonic drinks, but energy drinks contained greater quantities of Ag, Cr, Zn, Mn, and Mo and toxic elements, as Cd and Pb. A comparison of element contents with micronutrient intake and tolerable levels was performed to evaluate contribution of the investigated beverages to the daily diet. The consumption of 250 cm(3) of an isotonic drink provides from 0.32% (for Mn) up to 14.8% (for Na) of the recommended daily intake. For the energy drinks, the maximum recommended daily intake fulfillment ranged from 0.02% (for V) to 19.4 or 19.8% (for Mg and Na).

Production and characterization of low-calorie orange nectar containing stevioside

The study was carried out to produce and characterize a low-calorie orange nectar using response surface methodology (RSM). To optimize the formulation, three different levels of independent variables; sugar, stevioside and pectin and two responses of Brix and viscosity were selected. In the optimum formulation, sugar content reduced to 70 % (compared to control sample) using stevioside and pectin with maximum levels of 0.06 and 0.03 %, respectively. Physicochemical properties of optimal and control samples were determined at refrigerated (4 °C) and ambient (25 °C) temperatures for 2 months. At refrigerator, the reduction rate for stevioside was 5 % while a decrease of 18 % was observed at ambient temperature. The vitamin C content in low-calorie orange nactar was 13.4 % higher than control sample at both temperatures. Thus the production of low-calorie orange nectar using stevioside could be industrially feasible and recommended to people who looking for dietetic foods.

Prevalence and correlates of anaemia in adolescents in Riyadh city, Kingdom of Saudi Arabia

OBJECTIVE

To determine the prevalence and correlates of anaemia in male and female adolescents in Riyadh, Kingdom of Saudi Arabia.

DESIGN

A cross-sectional community-based study.

SETTING

Five primary health-care centres in Riyadh.

SUBJECTS

We invited 203 male and 292 female adolescents aged 13-18 years for interview, anthropometric measurements and complete blood count. Blood Hb was measured with a Coulter Cellular Analysis System using the light scattering method.

RESULTS

Using the WHO cut-off of Hb<12 g/dl, 16·7 % (n 34) of males and 34·2 % (n 100) of females were suffering from anaemia. Mean Hb in males and females was 13·5 (sd 1·4) and 12·3 (sd 1·2) g/dl, respectively. Values for mean cell volume, mean cell Hb, mean corpuscular Hb concentration and red cell distribution width in male and female adolescents were 77·8 (sd 6·2) v. 76·4 (sd 10·3) μm(3), 26·1 (sd 2·7) v. 25·5 (sd 2·6) pg, 32·7 (sd 2·4) v. 32·2 (sd 2·6) g/dl and 13·9 (sd 1·4) v. 13·6 (sd 1·3) %, respectively. Multivariate logistic regression revealed that a positive family history of Fe-deficiency anaemia (OR=4·7; 95 % CI 1·7, 12·2), infrequent intake (OR=3·7; 95 % CI 1·3, 10·0) and never intake of fresh juices (OR=3·5; 95 % CI 1·4, 9·5) and being 13-14 years of age (OR=3·1; 95 % CI 1·2, 9·3) were significantly associated with anaemia in male adolescents; whereas in females, family history of Fe-deficiency anaemia (OR=3·4; 95 % CI 1·5, 7·6), being overweight (OR=3·0; 95 % CI 1·4, 6·1), no intake of fresh juices (OR=2·6; 95 % CI 1·4, 5·1), living in an apartment (OR=2·0; 95 % CI 1·1, 3·8) and living in a small house (OR=2·5; 95 % CI 1·2, 5·3) were significantly associated with anaemia.

CONCLUSIONS

Anaemia is more prevalent among Saudi female adolescents as compared with males. Important factors like positive family history of Fe-deficiency anaemia, overweight, lack of fresh juice intake and low socio-economic status are significantly associated with anaemia in adolescents.

Precision of dehydroascorbic acid quantitation with the use of the subtraction method--validation of HPLC-DAD method for determination of total vitamin C in food

In food analysis, a method for determination of vitamin C should enable measuring of total content of ascorbic acid (AA) and dehydroascorbic acid (DHAA) because both chemical forms exhibit biological activity. The aim of the work was to confirm applicability of HPLC-DAD method for analysis of total content of vitamin C (TC) and ascorbic acid in various types of food by determination of validation parameters such as: selectivity, precision, accuracy, linearity and limits of detection and quantitation. The results showed that the method applied for determination of TC and AA was selective, linear and precise. Precision of DHAA determination by the subtraction method was also evaluated. It was revealed that the results of DHAA determination obtained by the subtraction method were not precise which resulted directly from the assumption of this method and the principles of uncertainty propagation. The proposed chromatographic method should be recommended for routine determinations of total vitamin C in various food.

Determination of vitamin C in foods: current state of method validation

Vitamin C is one of the most important vitamins, so reliable information about its content in foodstuffs is a concern to both consumers and quality control agencies. However, the heterogeneity of food matrixes and the potential degradation of this vitamin during its analysis create enormous challenges. This review addresses the development and validation of high-performance liquid chromatography methods for vitamin C analysis in food commodities, during the period 2000-2014. The main characteristics of vitamin C are mentioned, along with the strategies adopted by most authors during sample preparation (freezing and acidification) to avoid vitamin oxidation. After that, the advantages and handicaps of different analytical methods are discussed. Finally, the main aspects concerning method validation for vitamin C analysis are critically discussed. Parameters such as selectivity, linearity, limit of quantification, and accuracy were studied by most authors. Recovery experiments during accuracy evaluation were in general satisfactory, with usual values between 81 and 109%. However, few methods considered vitamin C stability during the analytical process, and the study of the precision was not always clear or complete. Potential future improvements regarding proper method validation are indicated to conclude this review.

Glassy carbon electrodes modified with multiwalled carbon nanotubes for the determination of ascorbic acid by square-wave voltammetry

Multiwalled carbon nanotubes were used to modify the surface of a glassy carbon electrode to enhance its electroactivity. Nafion served to immobilise the carbon nanotubes on the electrode surface. The modified electrode was used to develop an analytical method for the analysis of ascorbic acid (AA) by square-wave voltammetry (SWV). The oxidation of ascorbic acid at the modified glassy carbon electrode showed a peak potential at 315 mV, about 80 mV lower than that observed at the bare (unmodified) electrode. The peak current was about threefold higher than the response at the bare electrode. Replicate measurements of peak currents showed good precision (3% rsd). Peak currents increased with increasing ascorbic acid concentration (dynamic range = 0.0047-5.0 mmol/L) and displayed good linearity (R(2) = 0.994). The limit of detection was 1.4 μmol/L AA, while the limit of quantitation was 4.7 μmol/L AA. The modified electrode was applied to the determination of the amount of ascorbic acid in four brands of commercial orange-juice products. The measured content agreed well (96-104%) with the product label claim for all brands tested. Recovery tests on spiked samples of orange juice showed good recovery (99-104%). The reliability of the SWV method was validated by conducting parallel experiments based on high-performance liquid chromatography (HPLC) with absorbance detection. The observed mean AA contents of the commercial orange juice samples obtained by the two methods were compared statistically and were found to have no significant difference (P = 0.05).

Green synthesis of gold-chitosan nanocomposites for caffeic acid sensing

In this work, colloidal gold nanoparticles (AuNPs) stabilized into a chitosan matrix were prepared using a green route. The synthesis was carried out by reducing Au(III) to Au(0) in an aqueous solution of chitosan and different organic acids (i.e., acetic, malonic, or oxalic acid). We have demonstrated that by varying the nature of the acid it is possible to tune the reduction rate of the gold precursor (HAuCl(4)) and to modify the morphology of the resulting metal nanoparticles. The use of chitosan, a biocompatible and biodegradable polymer with a large number of amino and hydroxyl functional groups, enables the simultaneous synthesis and surface modification of AuNPs in one pot. Because of the excellent film-forming capability of this polymer, AuNPs-chitosan solutions were used to obtain hybrid nanocomposite films that combine highly conductive AuNPs with a large number of organic functional groups. Herein, Au-chitosan nanocomposites are successfully proposed as sensitive and selective electrochemical sensors for the determination of caffeic acid, an antioxidant that has recently attracted much attention because of its benefits to human health. A linear response was obtained over a wide range of concentration from 5.00 × 10(-8) M to 2.00 × 10(-3) M, and the limit of detection (LOD) was estimated to be 2.50 × 10(-8) M. Moreover, further analyses have demonstrated that a high selectivity toward caffeic acid can be achieved without interference from catechin or ascorbic acid (flavonoid and nonphenolic antioxidants, respectively). This novel synthesis approach and the high performances of Au-chitosan hybrid materials in the determination of caffeic acid open up new routes in the design of highly efficient sensors, which are of great interest for the analysis of complex matrices such as wine, soft drinks, and fruit beverages.

Comparative study of chemical and biochemical properties of different melon cultivars: standard, hybrid, and grafted melons

Chemical and biochemical properties of standard, hybrid, and grafted melons cultivated under the same agricultural conditions in adjacent fields in the Cumra region of Turkey were investigated and compared based on pH, Brix, antioxidant activity, total phenolics, ascorbic acid, individual phenolics, sugar, and organic acid values. Seventeen different phenolic constituents were quantified by reverse phase high-performance liquid chromatography (RP-HPLC). The highest phenolic acid variability and content were detected in the standard melon. Sugar and organic acid compositions of melon cultivars were tested by capillary electrophoresis, and significant differences in types and contents of individual sugars and organic acids were determined among the cultivars. Standard Cinikiz Cumra melons had the highest ascorbic acid, total phenolics, and total sugar contents. The fructose/glucose ratio increased three times in grafted melon as compared with standard melon. While sugar alcohol mannitol existed in the standard and hybrid cultivars, this constituent disappeared in the grafted types. Citric acid found in the standard cultivar was not detected in the hybrid and grafted types. Consequently, it was concluded that the nutritional value of melons changed by the application of hybridization, grafting, or standard (open pollinated) production methods. The standard melon was found to have the highest score in terms of taste, because of its highest sweetness and sourness. It was also found preferable because of its high antioxidant activity, total phenolic and ascorbic acid contents.