Impact of microencapsulated watermelon (Citrullus lanatus) and beetroot (Beta vulgaris L) on storage stability of l-citrulline and dietary nitrate.

The aim the current study was to developed a watermelon rind powder (WRP), watermelon pulp powder (WPP), and beetroot powder (BP), in order to compare the stability of L-citrulline and nitrate with that of watermelon rind juice (WRJ), watermelon pulp juice (WPJ), and beetroot juice (BJ), respectively. The stability was evaluated during 32 days at 25, 4 and - 20 ºC. L-arginine and L-ornithine content were also evaluated. At day 0, a significantly higher L-citrulline and L-ornithine content in WRP was observed when compared to WPP. However, a significantly lower L-arginine content in WRP was observed when compared to WPP. L-citrulline content in WRP and WRJ was stable over 32 days in all temperatures evaluated, whereas it reduced in WPP in 32 days at 25 ºC and it is reduced in in WPJ in day 16 and day 32 at 25 °C. L-arginine content in WRP and WPP was stable over 32 days in all temperatures evaluated. A reduction was observed in WRJ at day 2, 4 and 32 at 25 °C and in WPJ at day 2, 4, 8, 16 and 32 days at 25 °C. L-ornithine content in WRP and WPP was stable over 32 days in all temperatures evaluated. An increase was observed in WRJ at day 2, 4 and 32 at 25 °C and in WPJ in day 2, 4, 8, 16 and 32 at 25 °C. Nitrate content in BP was stable over 32 days in all temperatures evaluated, while nitrate content in beetroot juice was reduced in day 2 at 25 °C and day 8 at 4 °C. In conclusion, L-citrulline of the microencapsulated watermelon rind and nitrate of the microencapsulated beetroot were stable throughout storage.

Flow-Mediated Dilation in Healthy Young Individuals Is Impaired after a Single Resistance Exercise Session.

The current pool of data investigating the effects of a single resistance exercise session on endothelial function is divergent and inconclusive. Therefore, the purpose of the present study was to evaluate the effect of a single resistance exercise session on flow-mediated dilation (FMD) in trained individuals. Eleven healthy, young, recreationally resistance-trained individuals participated in the study. After determining the resistance exercise workload, the participants performed three sets of 10-12 repetition of leg press and leg extension exercises. By using ultrasound equipment, brachial artery FMD was assessed before (PRE) and 30 min after (POST) the resistance exercise protocol or resting (control) to evaluate endothelial function. A significant reduction in FMD response (PRE: 5.73% ± 1.21% vs. POST: 4.03% ± 1.94%, p < 0.01) after resistance exercise was observed, accompanied by a large effect size (d = 1.05). No significant difference was observed in FMD in the control condition (PRE: 5.82% ± 1.19% vs. POST: 5.66% ± 1.24%, p = 0.704). Additionally, no significant difference in baseline brachial artery diameter between resistance exercise (PRE: 3.30 ± 0.32 vs. POST: 3.40 ± 0.34 mm, p = 0.494) and resting (PRE: 3.64 ± 0.41 vs. POST: 3.67 ± 0.62 mm, p = 0.825) was observed. Our findings showed that a single resistance exercise session induced a reduction in FMD in resistance-trained individuals.

Combined effect of high hydrostatic pressure and ultraviolet radiation on quality parameters of refrigerated vacuum-packed tilapia (Oreochromis niloticus) fillets.

This study investigated the effects of high hydrostatic pressure (HHP) and ultraviolet radiation (UV-C), individually and combined, on the physical, chemical and bacterial parameters of Nile tilapia (Oreochromis niloticus) fillets stored at 4 °C for 14 days. Tilapia fillets were divided into four groups: control (untreated samples), UV-C, HHP, and UV-C combined with HHP (UV-C+HHP); UV-C was applied at dose of 0.103 ± 0.002 J/cm2, and HHP at a pressure of 220 MPa for 10 min at 25 °C. All samples were analyzed for total aerobic mesophilic count (TAMC), total aerobic psychrotrophic count (TAPC), Enterobacteriaceae count, pH, lipid oxidation, total volatile basic nitrogen (TVB-N), ammonia (NH3), and biogenic amines. Although UV-C accelerated (P ≤ 0.05) the formation of cadaverine, both UV-C and HHP, alone or together, retarded bacterial growth and delayed the increase (P ≤ 0.05) in pH, TVB-N, NH3 and biogenic amines during refrigerated storage, extending the shelf life of refrigerated tilapia fillets at least 2.5 times considering the TAMC counts. Lipid oxidation was unaffected (P > 0.05) by UV-C radiation, and decreased (P ≤ 0.05) by HHP and UV-C+HHP. HHP alone or combined with UV-C showed higher potential benefits for tilapia fillets preservation considering the positive influence on cadaverine levels and lipid oxidation.

A Single Dose of Beetroot Gel Rich in Nitrate Does Not Improve Performance but Lowers Blood Glucose in Physically Active Individuals.

Background. Beetroot consumption has been proposed to improve exercise performance, since the nitrate content of this food is able to stimulate the synthesis of nitric oxide. Objective. The acute effect of 100 g of a beetroot gel containing ~10 mmol of nitrate was tested on the nitric oxide synthesis, on metabolic and biochemical parameters, and on performance in physically active individuals. Methods. Through a double blind, crossover, placebo-controlled study, 25 healthy runners ingested a single dose of beetroot and placebo gels. Participants performed an aerobic exercise protocol on a treadmill (3 min warm-up of 40% peak oxygen consumption, 4 min at 90% of gas exchange threshold I and 70% (Δ) maximal end speed until volitional fatigue). Results. Urinary levels of nitrite and nitrate increased after 90 min of beetroot gel ingestion. Plasma glucose concentrations lowered after the exercise and the decrease was maintained for 20 min. Systolic and diastolic blood pressures, serum cortisol, and blood lactate were not altered after the beetroot gel ingestion compared to a placebo gel. Conclusion. The single dose of beetroot gel provoked an increase of nitric oxide synthesis although no improvement on the physical performance of athletes during aerobic submaximal exercise was observed.

La suplementación de la L-arginina no afecta la producción de óxido nítrico ni la recuperación muscular / No effect of L-arginine supplementation on nitric oxide production and muscle recovery

Introducción: La L-arginina (L-Arg) es un aminoácido semiesencial y precursor de la síntesis de óxido nítrico (NO). Recientemente, los suplementos nutricionales que contiene L-Arg son comercializados con la pretensión de promover vasodilatación, debido al aumento de la producción de NO en músculo. El resultado de la vasodilatación elevaría la perfusión sanguínea, promoviendo un mayor aporte de nutrientes y oxigeno, los cuales pueden mejorar el rendimiento y la recuperación muscular. Propósito: Identificar el efecto agudo de la suplementación con L-Arg sobre la ratio de recuperación del trabajo (WRR), potencia media, trabajo total (TW3S) y los indicadores de producción de NO, nitrito y nitrato plasmático (NOx), durante el ejercicio de contra-resistencia. Métodos: Diecisiete hombres sanos y entrenados, participaron en un estudio, doble ciego, controlado con placebo. Se tomaron muestras de sangre antes y 90 min después de la ingesta de 6 g de LArg o placebo. El protocolo de ejercicio (3 series de 10 repeticiones máximas de extensión de codo isocinético concéntrico en 60º.s-1 con 2 min de descanso entre las series) se inició 80 minutos después de la suplementación. Mediciones de NOx se realizaron por el método de Griess usando un espectrofotómetro de absorción a 540 nm. Resultados: No se encontraron diferencias significativas entre el grupo suplementado con L-Arg vs placebo en lo referente parámetros de WRR, potencia media y TW3S (2630,4 ± 758,0vs 2573,1 ± 669,9 Joules). Además, no se observó diferenciasignificativa en el NOx plasmático, en ningún momento, entre el grupo suplementado con L-Arg vs placebo, antes de la suplementación (9,8 ± 2,3vs 9,5 ± 1,4 micro mol/L) o inmediatamente después del ejercicio (11,9 ± 5,5 vs 10,2 ±2,3 micro mol/L). Conclusión: Nuestros resultados indican que la ingesta aguda de L-Arg no aumenta la producción de NO, ni mejora el rendimiento recuperación muscular. En base a estos resultados, es precipitado recomendar suplementos nutricionales que contienen L-Arg como ayuda ergogénica para optimizar la recuperación muscular después del ejercicio de contra-resistencia en individuos sanos y entrenados (AU)

Introduction: L-arginine (L-Arg) is a semi-essential aminoacid precursor to nitric oxide (NO) synthesis. Recently, nutritional supplements containing L-Arg have been marketed with the purpose of promote vasodilation, due to an increased production of NO in the exercising muscle. The resulting vasodilation would elevate blood perfusion, leading to a higher nutrient and oxygen delivery, which may enhance exercise performance and muscular recovery. Purpose: Identify the acute effect of L-Arg supplementation on work recovery ratio (WRR), average power, total work (TW3S) and indicators of NO production, plasma nitrite and nitrate(NOx), during a resistance exercise protocol. Methods: Seventeen healthy and resistance-trained males participated in a randomized, double-blind, placebo-controlled study. Blood samples were collected before and 90 min (immediately post-exercise) after ingestion of oral 16g of L-Arg or placebo. The exercise protocol (3 sets of 10 maximal voluntary contractions of isokinetic concentric elbow extension at 60 o.s-1with 2-min of rest between sets) was initiated 80 min after supplementation. NOx measurements were made by a traditional Griess reaction colorimetric method using a spectrophotometer monitoring absorbance at 540 nm. Results: No significant difference between L-Arg versus placebo supplemented groups was observed on WRR, average power and TW3S (2630.4 ± 758.0 versus 2573.1 ± 669.9 Joules). Furthermore, no significant difference was observed in plasma NOx at any time point between L-Arg versus placebo supplemented groups at baseline (9.8 ± 2.3 vs. 9.5 ± 1.4 micre mol/L) and immediately post-exercise (11.9 ± 5.5 vs. 10.2 ±2.3 micremol/L). Conclusion: Our data indicates that acute ingestion of L-Arg does not increase NO production nor enhances muscle performance and recovery. Based on this fact, it is still premature to recommend nutritional supplements containing L-Arg as an ergogenic aid to optimize muscle recovery after resistance exercise bouts in healthy and resistance-trained subjects (AU)