1,721,051 research outputs found
Eugenol, obtained from the bioassay-guided fractionation of Coriandrum sativum essential oil, displayed antioxidant effect in deep-frying procedure of sunflower oil and improved sensory properties of fried products, Caijiao
No full textThe deep-frying procedure of Caijiao in sunflower oil (SFO) needs natural antioxidants. In the present study, the essential oil of Coriandrum sativum (CSEO) was added into SFO at 0.16 g/kg to prepare SFO sample. During the deep-frying procedure of Caijiao, total polar compounds (TPC), thiobarbituric acid (TBA), conjugated dienes (CD), conjugated trienes (CT), polymers, viscosity and b* were prominently inhibited, together with the obvious reduction of L* (p < 0.01 or p < 0.05). The sensory attributes of Caijiao were also obviously improved (p < 0.01 or p < 0.05). In the meantime, the addition of synthetic antioxidants to SFO, such as TBHQ, BHA and BHT, didnt display effective antioxidant effect. After the bioassay-guided fractionation, the antioxidant effect of CSEO was attributed to one of its natural products, eugenol. The research and development of eugenol for effective natural antioxidants is of much importance for the whole food industry
Interaction of surfactants with phospholipid vesicles in the low concentration regime
No full textThe interactions between diluted phospholipid vesicles (0.3 μM - 40 μM) and surfactants (around their cmc) have been investigated as model of the phenomena taking place when enveloped viruses are challenged by detergent formulations such as mouthwashes or dishwashing liquids. We have used negatively charged Small Unilamellar Vesicles (SUVs) to simulate the negatively charged viral envelope and surfactants with different charges: the anionic Sodium Dodecyl Sulphate (SDS), the cationic Cetylpyridinium Chloride (CPC) and the non-ionic Octaethylene glycol monodecyl ether (C10E8). Dynamic and Electrophoretic Light Scattering have been used to probe variations in size and surface charge of the vesicles. The surfactants effect on the membrane permeability was investigated by measuring the fluorescence of SUVs secluding the fluorophore calcein. All the surfactants perturb the bilayer inducing graded dye leakage. Irrespective of the chemical nature of the surfactant, the membrane leakage follows the same sigmoidal master curve when it is plotted against the ratio surfactant concentration/cmc. The membrane leakage is negligible below cmc/2 and above such a value increases up to the cmc where all the dye has been fully released. For ionic SDS and CPC the dependence of leakage halftime on such a scaled concentration is the same irrespective of the charge of the surfactant and the vesicles. The nonionic surfactant C10E8 induces the dye release from the SUV two orders-of-magnitude faster than the ionic surfactants. These results show that the rate-determining parameter for the permeabilization of the lipid bilayers is the electrostatic penalty to the flip-flop required to transport the surfactant inside the vesicle
Oxidative modifications of conjugated and unconjugated linoleic acid during heating
No full textThe oxidative stability of conjugated linoleic (CLA) and linoleic (LA) acids in different chemical forms (free acids, methyl esters and homogeneous triacylglycerols) was compared. All model systems were heated at 180°C for different times (15, 30, 45 and 60 min). The primary oxidation products were evaluated by spectrophometric analysis, while the volatile compounds were determined by solid phase microextraction (SPME), coupled with gas chromatography-mass spectrometry (HRGC-MS). The isomer profile modifications were investigated by silver ion high performance liquid chromatography (Ag+-HPLC) equipped with an UV detector. Generally, peroxide values decreased during the heating time.
Among the volatiles, saturated aldehydes were the most represented
compounds. Isomerization of cis,trans and trans,cis CLA to trans,trans
isomers was observed mainly for the methyl form of CLA. The three
different chemical forms of LA never showed isomerization phenomena
Characterization of Volatile Fraction of Saffron from Central Italy (Cascia, Umbria)
No full textSaffron, the world's most expensive spice, is valuable for its color, taste, aroma, and properties, which are influenced by the postharvest treatments. In this research solid-phase micro-extraction coupled with gas chromatography-mass spectrometry was performed to analyze saffron produced in the area of Cascia, central Italy. The samples were dried under different conditions as a function of time and temperature. The main volatiles in addition to safranal were isophorone, 4-ketoisophorone, and 2,2,6-trimethyl-1,4-cyclohexanedione. In some samples, two new compounds (2,4,4-trimethyl-1-pentene and 1,3,3-trimethyl-7-oxabicyclo[4.1.0]heptane-2,5-dione) were identified. Their content increased with drying temperature and time and they could be characteristic of saffron produced in the selected geographical area. Moreover the results confirmed that the drying conditions strongly influenced saffron volatile profile
Linear discriminant analysis on triacylglycerol stereospecific composition for the detection of milk adulteration
No full textVolatile compounds as indicators of conjugated and unconjugated linoleic acid thermal oxidation
No full textIn this research, volatiles arising from heating of conjugated (CLA) and unconjugated (LA) linoleic acid, in
different chemical forms (free acids, methyl esters, and homogeneous TAGs) have been studied. A solid
phase micro‐extraction (SPME) coupled with GC–MS was used to analyze the volatile compounds
produced during heating at 180°C for different times (15, 30, 45, and 60min). Numerous types of volatiles
have been identified such as aldehydes, furan fatty acids (FA), alcohols, methyl esters, and methyl‐oxoacids.
Results showed that aldehydes were the main volatile compounds both in CLA and LA, even if some
differences were found between conjugated and unconjugated systems. In particular, heptanal and trans‐2‐
octenal were detected mainly in CLA forms, while trans‐2‐heptenal in LA. Among furan FA, 2‐pentyl‐furan
content was higher in LA than in CLA at all treatment times, while 2‐hexyl‐furan was detected in free fatty
acid and methyl ester forms of CLA and it was never detected in LA model systems. Among alcohols,
1‐octen‐3‐ol was found only in LA forms. Methylated forms of CLA and LA provided high contents ofmethyl
esters, among whichmethyl octanoate was the most represented. Therefore heptanal, trans‐2‐octenal, 2‐hexylfuran
could be considered as characteristic compounds produced during CLA‐rich sample oxidation
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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