1,721,011 research outputs found
Thiabendazole uptake and storage performance of cactus pear [Opuntia ficus-indica (L.) Mill. Cv Gialla] fruit following postharvest treatments with reduced doses of fungicide at 52°C
No full textThe storage response of cactus pears [Opuntia ficus-indica Miller (L.) cv. Gialla] was investigated over 6 weeks at 6°C, plus an additional week of simulated marketing period (SMP) at 20°C, after a 3-min dip treatment with thiabendazole (TBZ) at 1000 mg/L at 20°C or 150 mg/L TBZ at 52°C. Untreated fruits were used as control. Following TBZ treatments at 20 and 52°C, total residues were recovered from the peel of cactus pear, as the concentration of residues in the pulp was negligible. Treatments with 1000 mg/L TBZ at 20°C resulted in a 2.82 mg/kg residue uptake (active ingredient, whole-fruit basis), whereas treatment at 150 mg/L TBZ left 1.09 mg/kg. TBZ showed great persistence over both storage and SMP: on average, in the fruits treated at 20 and 52°C, over 72 and 68%, respectively, of TBZ was still present after SMP. Postharvest treatments with 1000 mg/L TBZ at room temperature did not affect the expression of slight-to-moderate chilling injury (Cl), but reduced severe Cl by approximately 50% and decay development by 63.4% in comparison to those of untreated fruit after SMP. The effectiveness of TBZ was much higher with the treatment at 150 mg/L TBZ at 52°C, providing 91% control of severe Cl and approximately 89% suppression of decay; no treatment damage occurred during storage and SMP. External appearance was better in fruit treated with 150 mg/L TBZ at 52°C. Respiration rate, titratable acidity, soluble solids concentration, and acetaldehyde in the flesh were not significantly influenced by treatments. Ethylene production rate and ethanol levels in the flesh were significantly higher in the TBZ-treated fruit as opposed to those in the untreated control fruit
Determinazione di componenti aromatiche del vino e correlazione con l’attività fermentativa
No full textChiral resolution of acetoin and 2,3-butanediols by GC-MS as a tool for the characterization of fermenting yeast
No full textMEMBRANE PHOSPHOLIPIDS METABOLISM IN ACTIVATED PLATELETS
No full textIntroduction: In vitro platelets activation induced by Collagen is a good model that mimics the events occuring "in vivo" by consequence of the exposure of the subendothelial matrix to the blood stream due to vessel damage. The interaction of Collagen with the platelet membrane receptor VLA-2 (the alfa2-beta1 integrin) is followed by intraplatelet processes leading to the secretion of granules content and formation of aggregates. The correct sequence of these events is yet unknown. "Active metabolites" of PLC (IP3, DG) and PL-A2 (Arachidonic Acid) are produced after the agonist-receptor complex formation but it is uncertain whether their rise is due to direct transduction of the external signal or is induced by the activation of phospholipases by second intracellular messengers. Aggregation induced by Collagen is preceded by a lag phase (20-40 sec) during which the shape of platelets changes from discoid to spiny sphere.
Methods: Aggregation was followedby the light transmission
increase measured by Aggrecoder II (Menarini); TBARS were determined by the method reported in (1); Phospholipids were determined after thin-layer chromatography as in (2).
Results and Discussion: We investigated the time courses of the production of TBARS (an indication of TX-A2 formation by Arachidonic Acid oxidative metabolism) and of the changes in the membrane phospholipids composition (namely PC, PE and PI). TBARS appearance was slightly faster than aggregates formation but was markedly preceded by membrane phospholipids degradation. The phospholipid undergoing the fastest metabolism was PI (which reached the maximal changes in a few seconds) followed by PE and PC. PI consumption is considered a good indication for the metabolism of all the phosphatidyl inositides
(including PIP and PIP2). Being these phospholipids the preferred substrates for PL-C, we conclude that the first, fast, effect of the agonist-receptor complex formation is activation of PL-C. The consequence of PL-C activation is the pro-duction of IP3 and DG, the former being necessary to liberate Ca2+ and the latter to activate PK-C (and consequently the contractile system).
The delay of the consumption of PE and PC could be due to the fact that these phospholipids are the preferred substrates for
PL-A2: Ca2+ could be the second intracellular messenger necessary to trigger the Arachidonic Acid relase from which TX-A2 is produced. TX-A2 acts by two different ways: 1) it amplifies the intracellular signal by its strong activity in dissequestering Ca2+ from stores; 2) it propagates the stimulus to other platelets by its strong agonist activity.
Bibliography
1-Slater T.F. (1984, Methods in Enzymology 105, 283-293,
2-Jork H., Wimmer H. Quantitative Auswertung von Duennschicht Chromatogrammen. Darmstadt: GIT-Verlag, p.III./ 3-82
Determination of 2,3-butanediol in high and low acetoin producers of Saccharomyces cerevisiae wine yeast by automated multiple development (AMD)
No full textHigh performance thin layer chromatography with automated multiple development was used to determine 2,3-butanediol levels in wine produced by high and low acetoin-forming strains of Saccharomyces cerevisiae. An inverse correlation between acetoin and 2,3-butanediol content was found suggesting a leaky mutation in acetoin reductase of the low 2,3-butanediol producing strains
Determination of 2,3-butanediol in high and low acetoin producers of Saccharomyces cerevisiae wine yeasts by automated multiple development (AMD). Lett. Appl. Microbiol., 22: 299-302.
No full textResidue levels and storage decay control in ‘Star Ruby’ grapefruit after dip treatments with azoxystrobin
No full textInfluence of Saccharomyces cerevisiae strains on wine total antioxidant capacity evaluated by photochemiluminescence
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