1,721,038 research outputs found
Study of enriched olive oil with high nutritional and biological value: olives and hazelnuts co-pressing
No full textOlive oil is the main source of fat in the Mediterranean diet and its consumption has been related to a low incidence of coronary heart disease and certain cancers. These protective effects are attributed mainly to two fundamental components of oilve oil: monounsaturated fatty acids (MUFA) and antioxidant substances.
Also nuts are included in healthy diets and, among them, hazelnuts (Corylus avellana L.) are very interesting as a source of nutritious food with a high content of functional lipids. Hazelnut’s benefits are mainly related to its fatty acid composition, rich in MUFA, tryacylglycerol profile, tocopherols and other bioactive compounds like phytorterol and polyphenols.
On the basis of these considerations the aim of this work was to investigate the quality of an olive oil obtained by a co-pressing of olives and hazelnuts. In particular, three different samples were studied: olive oil obtained crushing 0% (O), 5% (O5N) and 10% (O10N) of hazelnuts.
Classical methods based on gas-chromatography (GC) and high-performance liquid chromatography (HPLC) have been used for fatty acid, tryacylglycerol, phytosterol and tocopherol characterization. No significant differences were noticed among the three olive oils, except for phytosterols. The small components 7-stigmastenol and 7-avenasterol, charatcteristic of the hazelnut sterol profile, were found to be present in higher amount in samples O5N and O10N than the simple olive oil
Besides, the samples were also analysed by FT-MIR spectroscopy in the frequency range 1500 -900 cm-1. The FT-MIR spectra were processed by using principal component analysis (PCA) and partial least squares regression (PLS). The first one was used to discriminate the sample oils with different content ofhazelnut, instead the second one was employed to predict tocopherol and tryacylglycerol content (R2 up to 0.87 in cross verification
Buckwheat honeys: Screening of composition and properties
No full textThe quality of 10 buckwheat honeys, collected from Italian and est European beekeepers declaring to produce
monofloral honey, were evaluated by means of their pollen, physicochemical, phenolic and volatile
composition data. The results of the traditional analyses and in particular electrical conductivity, optical
rotation, pH and sugar composition revealed some poorly pure samples that could not fit in the buckwheat
tipology. Honey volatiles, analysed by solid phase microextraction (SPME) and gas chromatography–
mass-spectrometry (GC/MS), showed more than 100 volatile compounds, most of them present in
all honey samples but with quantitative variation. Besides many furfural derivates, 3-methylbutanoic
acid was the main volatile compound found in most of honeys. Also the presence of 2- and 3-methylbutanal
and pheynalcetaldehyde confirmed the typical buckwheat aroma of some studied samples, corroborating
physicochemical data. The HPLC phenolic profile was similar across the samples and phydroxybenzoic
and p-coumaric acids proved to be the main components
Influence of postharvest drying process on walnut bioactive compounds
No full textWalnuts (Juglans regia L.) are an important component of the Mediterranean diet and they have been long consumed as a highly nutritious food in many parts of the world. Walnut consumption was associated with lower BMI, waist circumference, systolic blood pressure and higher high density lipoprotein-cholesterol, compared with no consumption. These effects have been attributed to different bioactive compounds that have been contained in these nuts.
However, walnuts are consumed after a drying process; because of that the aim of this work is to determine the influence of drying on some bioactive compounds. Three different walnut samples were obtained from a local company located in Forli (Italy). The fresh samples were drying as reported in the regional advisories for Integrated Crop Management. Fatty acids, sterols, tocopherols and phenolic compounds have been analyzed in fresh and dried walnut samples.
The major fatty acids found in walnuts are oleic (18:1), linoleic (18:2), and linolenic (18:3) acids; no statistical differences were noticed among fresh and dried samples. Four tocols were also identified. Gamma-tocopherol was the principal tocol determined in walnut samples; drying process increased the tocols content. GC-MS analysis permitted the identification of six sterols. As expected, sitosterol represented the first sterol compound in all samples. Drying process negatively affected the sterols content; in fact total sterol losses ranged from 6 to 34 %. Finally, walnut phenolic compounds were determined by HPLC-MS. A total of 45 phenolic compounds were identified and quantified. As expected, gallic and ellagic derivatives represented 88.6-90.2 % of total phenolic compounds. As reported for sterols, phenolic compounds content decreased (19-44%) from fresh to dried walnut samples
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
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Survival of the functional yeast Kluyveromyces marxianus B0399 in fermented milk with added sorbic acid
No full textIn this study, the survival of the functional yeast Kluyveromyces marxianus B0399 in an industrially produced fermented milk was evaluated. In particular, the yeast viability was assessed throughout the entire shelf-life of the product (30 d) to ensure the presence of the effective yeast dose (20 million viable cells for each serving of 125 g) while avoiding, by sorbic acid addition, yeast growth, which could affect product quality and stability. To find the best combination of yeast and sorbic acid concentration, 13 different combinations were tested, and then 2 of them were chosen for industrial production. In production at lower concentrations (30 million viable cells, 150 mg/kg of sorbic acid) the effective dose was maintained only at 4 and 6°C, whereas at higher dosages (70 million viable cells, 250 mg/kg of sorbic acid) the effect of temperature was less evident. In all the trials, the concentration of sorbic acid was not affected by microbial metabolism and remained stable throughout the entire shelf-life
Study of the effects of different roasting conditions on physical-chemical and biochemical properties of polish hazelnuts (Corylus avellana L. var. Kataloński)
No full textHazelnut (Corylus avellana L.) is one of the most popular nuts worldwide and plays an important role in human nutrition and health, because it is a rich source of fat, protein, carbohydrate, dietary fibre, minerals vitamins, phytosterols and antioxidant phenols (1). Due to their organoleptic characteristics, hazelnut is also used as an ingredient in a variety of processed foods including confectionary, chocolates and desserts. More frequently, the kernels are roasted in order to improve the aroma, texture and taste of products. The thermal treatment of nuts inevitably leads to chemical changes mainly determined by the nut composition and by the temperature and extent of heating
Because of that, the objective of this study was to evaluate the influence of different roasting intensities on the physical-chemical (activity water, moisture and colour) and biochemical (volatile compounds, tocopherols, phenolic content and antioxidative activity) properties of Polish hazelnuts (cv. Kataloński). According to the range commonly used in the hazelnut industry, nuts were roasted at six specific temperature/time conditions: 130 °C/40 min, 130 °C/50 min, 130 °C/60 min, 160 °C/20 min, 160 °C/25 min, 160 °C/30 min.
As expected, hazelnuts roasted at 160° C showed a darker color and a lower water activity and moisture than samples roasted at 130 °C.
Compared to raw hazelnuts, the phenolic content increased in all roasted samples, although with a more concentration in nuts roasted at 160° C. The antioxidant activity showed an initial decrease after roasting, reaching than a maximum in samples roasted at 130 °C/60 min and 160 °C/30 min.
Finally roasting contributed to release a lot of volatile compounds that belong to ketones, aldehydes, pyrazines, furans and other compounds. The different roasting conditions led to several aroma modification, in fact in raw hazelnuts were identified just only 22 compounds, whereas in samples roasted at 130° C and 160° C were found 79 and 102 volatiles,respectively . Among these, the 5-methyl-(E)-2-hepten-4-one (filbertone), which is considered the primary odorant of roasted hazelnut, was identified in all roasted samples
Determination of lipid and phenolic fraction in two hazelnut (Corylus avellana L.) cultivars grown in Poland
Full text linkThe fatty acid, tocopherol, sterol, phospholipid and phenolic compositions of Polish hazelnuts (Kataloński and Webba Cenny) were examined. Particularly, free + esterified and bound tocopherol, sterol and phenolic compounds were determined. The major fatty acids found in hazelnuts were oleic and linoleic acids. α-Tocopherol was the most abundant tocopherol accounting for 90-92% of the total content. Bound tocopherols represented 45.5% and 21.7% of total tocopherols in Kataloński and Webba Cenny cultivar, respectively. Total free + esterified sterols were between 62.0% and 75.7% of total sterols and β-sitosterol was the first sterol in the two samples. Phosphatidylcholine was the most common phospholipid, accounting for 72.2% for Kataloński and 67.5% Webba Cenny, respectively. The most abundant fatty acids in the phospholipid fraction were oleic equally with palmitic acids. Twelve free and six bound phenolic compounds were identified and quantified in hazelnut kernel, instead nine free and six bound phenolic compounds were determined in hard shell. © 2014 Elsevier Ltd. All rights reserved
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