Vitamin C. (vitamin + c)

Distribution by Scientific Domains

Selected Abstracts

Influence of Storage Temperature on the Kinetics of the Changes in Anthocyanins, Vitamin C, and Antioxidant Capacity in Fresh-Cut Strawberries Stored under High-Oxygen Atmospheres

I. Odriozola-Serrano
ABSTRACT:, Changes in the main antioxidant properties of fresh-cut strawberries stored under high-oxygen atmospheres (80 kPa O2) were studied at selected temperatures (5 to 20 °C). The suitability of zero- and 1st-order kinetics as well as a model based on Weibull distribution function to describe changes in experimental data is discussed. A non-Arrhenius approach was used to determine the temperature dependence of the estimated rate constants. A Weibull kinetic model most accurately (R2adj, 0.800) estimated changes in anthocyanins and antioxidant capacity of fresh-cut strawberries throughout the storage period, whereas a 1st-order model adequately fitted (R2adj, 0.982) the variation of vitamin C. The temperature dependency of the kinetic rate constants for each antioxidant property was successfully modeled through the non-Arrhenius approach (R2adj, 0.709). The Tc obtained for anthocyanins, vitamin C, and antioxidant capacity degradation were 290, 284, and 289 K, respectively, indicating the temperature at which a marked acceleration of the losses in the antioxidant potential of strawberry wedges occurs. These findings will help to describe the variation of the antioxidant potential of fresh-cut strawberries upon storage time and temperature. [source]

Physiological Responses of Nile Tilapia, Oreochromis niloticus, Fed Vitamin C- and Lipid-Supplemented Diets and Submitted to Low-Temperature Stress,

Dario R. Falcon
This study evaluated the effects of different levels of vitamin C and lipids on physiological responses of Nile tilapia, Oreochromis niloticus, submitted to temperature stress. There were two phases: Phase I , preparing fish to store vitamin C and lipid at appropriate temperature, and Phase II , evaluating the contributions these reserves make to fish physiology under low-temperature stress. The experiment used a 3 × 2 factorial design with three vitamin C levels (300, 600, and 1200 mg/kg diet) and two lipid levels (8.0 and 12.0%), plus absence of nutrient test and a diet of 6.0% lipids and 125.0 mg/kg vitamin C. In Phase I, 192 fish were kept at 26.0 ± 1.0 C for 112 d, and in Phase II, 48 fish were kept at 18.0 ± 0.5 C for 32 d and at 15.0 ± 0.5 C for 11 d. Fish fed C0L0 diet showed lower erythrocytes values in both phases; higher vitamin C supplement determined higher red blood cell (RBC) number and higher hematocrit (Htc) (Phase II); Htc was significantly lower in Phase II; after temperature stress, fish fed C0L0 diet had higher mean corpuscular volume, lower hemoglobin corpuscular concentration, and significantly lower vitamin C concentration in the liver; and higher supplementation determined a higher concentration in the liver (Phases I and II). Higher plasmatic cortisol concentration was seen in fish fed C0L0 diet. In conclusion, our results show that the absence of vitamin C in diets impairs RBC formation and does not enable fish to cope with stress; excess vitamin C is efficient in mitigating stress and 600 mg/kg diet is economic and physiologically sufficient to prepare fish for coping with low-temperature stress. Lipid supplementation does not determine alterations in stress biochemical parameters. [source]

Effects of a Vitamin E-Modified Dialysis Membrane and Vitamin C Infusion on Oxidative Stress in Hemodialysis Patients

Jaromír Eiselt
Abstract: Hemodialysis deteriorates oxidative stress. Vitamin E is an antioxidant whose regeneration is provided for by vitamin C. The authors tested the effects of a vitamin E-modified membrane (E), nonmodified cellulose membrane (O), and vitamin C infusion (500 mg, C) into the arterial blood line during dialysis on parameters of oxidative stress. In a short-term study, 24 patients were subjected to a single dialysis session with E, O, E with C, and O with C protocols. In a long-term study (12 weeks), 20 patients were randomized into groups with C and without C on each dialysis, and both groups had dialysis using O, E, and again O membrane for 4 weeks each. In the short-term study, thiobarbituric acid reacting substances (TBARS) in plasma rose after dialysis (p < 0.02) with O, and no changes were observed in the other 3 protocols. In the long-term study, predialysis TBARS declined when using E both in the groups with C (p < 0.02) and without C (p < 0.05). A switch over to O resulted in TBARS returning to baseline levels. The E membrane prevented an increase in lipid peroxidation during single dialysis, and long-term use of the E membrane also resulted in a decrease in the predialysis lipid peroxidation level. The antioxidant capacity of the E membrane was not enhanced by vitamin C infusion. High doses of vitamin C administered during dialysis using a nonmodified cellulose membrane prevented an increase in lipid peroxidation, most probably due to the enhanced rate of endogenous vitamin E regeneration. [source]

Extraction and chromatographic separation of anticarcinogenic fractions from cacao bean husk

BIOFACTORS, Issue 3 2005
Ki Won Lee
Abstract The utilization of cacao bean husk (CBH), a by-product of chocolate manufacture, would be both environmentally and economically beneficial. For this purpose, a process for effectively separating and fractionating CBH fractions having cancer preventive potential was developed in this study. For screening the fractions with potent cancer preventive activity, we examined the effect of extracts and fractions of CBH on the inhibition of gap-junction intercellular communication (GJIC) and the DNA synthesis of cancer cells, both of which are characteristics of the promotion and progression stages in carcinogenesis. The extracts of CBH (especially, the 60% ethanol fraction after extraction with 50% acetone) containing 43 wt.% polyphenol exerted an excellent protective effect on H2O2 -induced inhibition of GJIC in WB-F344 rat liver epithelial cells as determined by the scrape-loading/dye transfer assay. The enhancement of GJIC by the extracts of CBH was approximately 10-fold higher than that of a well-known dietary chemopreventive component, vitamin C. The extracts of CBH (especially, the 60% ethanol fraction) also suppressed DNA synthesis in all liver, stomach, and colon cancer cells as demonstrated by the 3H-thymidine incorporation assay, by approximately four-fold higher than that of vitamin C. These results imply that the polyphenol extracts and fractions of CBH are effective functional materials to be used in either preventing or inhibiting cancer. [source]

Von Seefahrern, Meerschweinchen und Citrusfrüchten.

Der lange Kampf gegen Skorbut
Obwohl der Skorbut die Menschheit von Anbeginn begleitet hat, wurde er erst im 16. Jahrhundert als Krankheit erkannt und es schloss sich eine Jahrhunderte andauernde Aneinanderreihung von kleinen Fortschritten und verpassten Chancen an. Erst zu Beginn des 20. Jahrhunderts identifizierten Wissenschaftler mit Hilfe von Meerschweinchen als Versuchstieren den Skorbut als eine Form von Mangelernährung. Dann begann ein spannender Wettlauf um die Isolierung, Strukturaufklärung und Synthese des Vitamin C. Heute ermöglicht die industrielle Vitamin-C-Synthese eine preiswerte Versorgung von jedermann. Diese Erfolgsgeschichte der modernen Chemie hat dafür gesorgt, dass der Skorbut aus unserem Leben nahezu vollständig verschwunden ist. Although scurvy has been around since the beginning of mankind, it was not until the 16th century that it was recognized as a disease. It took hundreds of years and a long sequence of small advances and missed opportunities to discover its cause. Finally at the beginning of the 20th century and with the help of guinea pigs for testing the experiments, scurvy was identified as a form of malnutrition. This started an exciting race for the isolation, structure determination, and synthesis of vitamin C. As a result, modern industrial synthesis now allows an affordable Vitamin C supply for everyone. This success story due to modern chemistry has made scurvy one of the many diseases that have almost entirely disappeared from our lives. [source]