The Effect of the Varietal Type, Ripening Stage, and Growing Conditions on the Content and Profile of Sugars and Capsaicinoids in Capsicum Peppers.

Peppers (Capsicum sp.) are used both as vegetables and/or spice and their fruits are used in a plethora of recipes, contributing to their flavor and aroma. Among flavor-related traits, pungency (capsaicinoids) and lately volatiles have been considered the most important factors. However, the knowledge of sugars is low, probably due to the fact peppers were historically considered tasteless. Here, using HPLC, we studied the content and profile of major sugars and capsaicinoids in a comprehensive collection of varietal types (genotype, G), grown under different growing systems (environment, E) in two years (Y) and considered the two main ripening stages (R). We found a major contribution to the ripening stage and the genotype in total and individual sugars and capsaicinoids. The year was also significant in most cases, as well as the G × E and G × Y interactions, while the growing system was low or nil. Ripening increased considerably in sugars (from 19.6 to 36.1 g kg-1 on average) and capsaicinoids (from 97 to 142 mg kg-1 on average), with remarkable differences among varieties. Moreover, sugars in fully ripe fruits ranged between 7.5 and 38.5 g kg-1 in glucose and between 5.2 and 34.3 g kg-1 in fructose, and several accessions reached total sugars between 40 and 70 g kg-1, similar to tomatoes. The results reveal the importance of the genotype and the ripening for these traits, particularly sugars, which should be considered key for the improvement of taste and flavor in peppers.

Speciation of chromium in natural waters by micropumping multicommutated light emitting diode photometry.

A simple and sensitive multicommutated flow procedure, implemented by employing a homemade light emitting diode (LED) based photometer, has been developed for the determination of chromium (VI) and total chromium in water. The flow system comprised a set of four solenoid micro-pumps, which were assembled to work as fluid propelling and as commutating devices. The core of the detection unit comprised a green LED source, a photodiode and a homemade flow cell of 100mm length and 2mm inner diameter. The photometric procedure for the speciation of chromium in natural waters was based on the reaction of Cr (VI) with 1,5-diphenylcarbazide. Cr (III) was previously oxidized to Cr (VI) and determined as the difference between total Cr and Cr (VI). After carrying out the assays to select the best operational conditions the features of the method included: a linear response ranging from 10 to 200mugl(-1) Cr (III) and Cr (VI) (r=0.999, n=7); limits of detection of 2.05 and 1.0mugl(-1) for Cr (III) and Cr (VI), respectively; a relative standard deviation lower than 2.0% (n=20) for a typical solution containing 50mugl(-1) Cr; a sampling throughput of 67 and 105 determinations per hour for total Cr and Cr (VI), respectively, and recovery values within the range of 93-108% for spiked concentrations of the order of 50mugl(-1).

Multicommuted flow system employing pinch solenoid valves and micro-pumps. Spectrophotometric determination of paracetamol in pharmaceutical formulations.

A multicommuted spectrophotometric flow-based procedure for the determination of paracetamol in pharmaceutical formulations is proposed. The method is based on the reaction of paracetamol with sodium hypochlorite forming N-acetyl-p-benzoquinoneimine, which reacts with sodium salicylate in alkaline medium producing a blue indophenol dye that was measured at 640nm. The flow system was designed employing four pinch solenoid valves and two solenoid micro-pumps, which were assembled aiming to obtain a compact module, resulting in minimization of reagents consumption and waste generation. Aiming to prove the usefulness of flow system an analytical procedure for paracetamol determination in pharmaceutical formulations was developed. To allow accuracy assessment samples were also analyzed using the AOAC reference method. Applying the paired t-test between results no significant difference at the 95% confidence level was observed. Other profitable features such as a linear response ranging from 5.0 to 125.0mgl(-1) (R=0.9992, n=7), a sampling rate of 60 determinations per hour, a detection limit of 0.4mgl(-1) paracetamol, a relative standard deviation of 1.5% (n=11) for a typical sample solution containing 25.0mgl(-1) paracetamol, reagent consumption of 1.28mg sodium hypochlorite and 6.4mg sodium salicylate per determination were also achieved.

Evaluation of the total antioxidant capacity by using a multipumping flow system with chemiluminescent detection.

An automated flow-based procedure for assessment of total antioxidant capacity was developed. It involved a multipumping flow system, a recent approach to flow analysis, and exploited the ability of selected compounds to inhibit the chemiluminescence reactions of luminol or lucigenin with hydrogen peroxide. The system included several discretely actuated solenoid micropumps as the only active components of the flow manifold. This enabled the reproducible insertion and efficient mixing of very low volumes of sample and reagents as well as the transportation of the sample zone toward a flow-through luminometer, where the chemiluminometric response was monitored. With luminol as the chemiluminogenic reagent, linearity of the analytical curves was noted up to 3.2x10(-4), 1.1x10(-3), and 8.8x10(-8) molL-1 for Trolox, ascorbic acid, and resveratrol, respectively. With lucigenin, linear calibration plots up to 2x10(-5) molL-1 of Trolox and 5.7x10(-5)molL-1 of ascorbic acid were obtained. As favorable analytical figures of merit, the measurement precision (RSD typically between 0.2 and 2.0%, n=10), low operational costs, low reagent consumption, sampling rate (160 and 70 h-1), and versatility should be highlighted. The proposed system can be used in distinct analytical circumstances without requiring physical reconfiguration.

Chemiluminometric determination of carvedilol in a multi-pumping flow system.

In this work a simple, fast, sensitive and selective flow-based procedure for the chemiluminometric determination of carvedilol, a recent non-cardioselective beta-blocker with noteworthy antioxidant activity, is proposed. The developed methodology takes advantage of the antioxidant capacity of carvedilol to inhibit the chemiluminescence response resulting from the oxidation of luminol by hypochlorite, by acting as a hypochlorite scavenger. The analytical process was implemented in a multi-pumping flow system that employs multiple solenoid actuated micro-pumps as the only active components. These acted as solution insertion, propelling and commuting units assuring an easily controlled, low cost, compact and reliable analytical system. A linear working range for carvedilol concentrations ranging from 1.2x10(-7) to 3.0x10(-6)moll(-1) (r>0.999, n=6), was obtained, with a detection limit of 8.7x10(-9)moll(-1). The system handles about 65 samples per hour yielding precise results (R.S.D.<1.3%, n=10). Recoveries within 95 and 104% were obtained.

An automatic flow procedure for the determination of 3-hydroxybutyrate in animal serum and plasma.

An automatic flow procedure based on the multicommutation concept, comprising three-way solenoid valves, for the spectrophotometric determination of 3-hydroxybutyrate in animal serum and plasma is proposed. The 3-hydroxybutyrate was enzymatically converted to acetoacetate with the reduction of NAD+ to NADH monitored at 340 nm. It was possible to carry out up to 600 determinations without a significant decrease in the analytical signal, with 5 mg of 3-hydroxybutyrate dehydrogenase immobilized on porous silica beads and packed in a column. The system enabled 60 determinations/h of 3-hydroxybutyrate in the range of 10-150 mg L(-1), with a consumption of 0.9 mg of NAD+ and 200 microL of sample per determination. A detection limit of 2 mg L(-1) for both animal serum and plasma and coefficients of variation of 1.4% and 1.2% (n = 17), respectively, were determined. Animal serum and plasma samples were analyzed without previous treatment, the results of which agreed with those obtained using the conventional method (UV kit, Sigma).

Multicommuted flow system for the determination of glucose in animal blood serum exploiting enzymatic reaction and chemiluminescence detection.

An automatic flow procedure based on multicommutation dedicated for the determination of glucose in animal blood serum using glucose oxidase with chemiluminescence detection is described. The flow manifold consisted of a set of three-way solenoid valves assembled to implement multicommutation. A microcomputer furnished with an electronic interface and software written in Quick BASIC 4.5 controlled the manifold and performed data acquisition. Glucose oxidase was immobilized on porous silica beads (glass aminopropyl) and packed in a minicolumn (15 x 5 mm). The procedure was based on the enzymatic degradation of glucose, producing hydrogen peroxide, which oxidized luminol in the presence of hexacyanoferrate(III), causing the chemiluminescence. The system was tested by analysing a set of serum animal samples without previous treatment. Results were in agreement with those obtained with the conventional method (LABTEST Kit) at the 95% confidence level. The detection limit and variation coefficient were estimated as 12.0 mg l(-1) (99.7% confidence level) and 3.5% (n = 20), respectively. The sampling rate was about 60 determinations h(-1) with sample concentrations ranging from 50 to 600 mg l(-1) glucose. The consumptions of serum sample, hexacyanoferrate(III) and luminol were 46 microl, 10.0 mg and 0.2 mg/determination, respectively.