1,720,972 research outputs found
Evaluation of hydrocarbon contaminants in olives and virgin olive oils from Tunisia
Full text linkThe present paper investigated on the presence of some hydrocarbon contaminants, namely polycyclic
aromatic hydrocarbons (PAHs), mineral oil hydrocarbons (MOH) comprising saturated (MOSH) and aromatic
(MOAH) compounds, and polyolefin oligomeric saturated hydrocarbons (POSH) in olives and
extra virgin olive oils from Tunisia. Olive fruits were collected in sites exposed to different environmental
contamination, and the oil extracted both by physical mean (using an Abencor extractor) and with
solvent (using microwave assisted extraction, MAE). Analytical determination was performed by SPE
cleanup on silica cartridge followed by spectrofluorometric detection, for PAH, and on-line HPLC-GC-FID
for MOH and POSH. Oils extracted from olives by physical mean, as well as extra virgin olive oils from the
market, had PAH levels never exceeding the EU legal limits. All olive samples showed similar MOSH
profiles, but not clear correlation between the variable contamination levels and considered sources of
contamination, was evidenced. The average MOSH content in oil extracted from olives by solvent
(11.1 mg/kg) was about four time higher than in oil extracted by physical mean (2.6 mg/kg). MOSH in
extra virgin oil from the market ranged from 10.3 to 38.0 mg/kg, while MOAH were not detected. The
higher MOSH levels found in oils from the market evidenced an important contribution due to oil
processing and/or packaging. Two of the samples were clearly contaminated with polyolefin oligomeric
hydrocarbons (POSH) migrated from the plastic cap
Fortification of wheat white bread: assessing the suitability of Beta vulgaris trough technological, nutritional, and sensory evaluation
No full textAs societies undergo shifts in dietary patterns, there is often an increase in nutrition-related issues. This is particularly evident in the case of wheat bakery products, which have evolved in an unsustainable way. The fortification of wheat flour with vegetables has emerged as a strategy to mitigate the imbalanced composition of white bread. The objective of this study is to address existing knowledge gaps regarding nutritional quality and technological characteristics of food-to-food fortified bakery products. A blend of Beta vulgaris powder (up to 5% of the total weight) was incorporated into commercial wheat white flour, and the resulting composition and technological parameters were analysed throughout the bread-making process, using standard methods (e.g., AAAC, ISO). The sensory assessment of the tested fortified baking products formulations was conducted. The 178 volunteer consumers noted the differences conveyed by B. vulgaris, but scored the taste and colour as acceptable (6 out of 9). Formulations containing moderate amounts of chard (e.g., 2%) were most appreciated. This study demonstrates that B. vulgaris can be employed to enrich white bread, particularly in minerals, such as calcium, magnesium, and iron, in a readily actionable manner that is well accepted by consumers. Furthermore, the use of flour blends contributes to mitigate the impact of fluctuations in wheat availability, thereby enhancing food security.10.54499/LA/P/0121/2020info:eu-repo/semantics/publishedVersio
Aroma compounds and sensory characteristics as biomarkers of quality of differently processed Tunisian virgin olive oils
No full textThe influence of the extraction system (continuous vs. discontinuous) and the degree of freshness of olives on the chemical composition and the quality of Chemlali and Chétoui virgin olive oil has been studied. Analytical data mainly concerning the volatile and sensory profiles revealed statistically significant differences in relation to the extraction system. All quality indices and sensory characteristics showed statistically significant differences associated with the degree of freshness of fruits. These results further confirm the general consensus that volatile compounds can be very useful as biomarkers of the quality of virgin olive oil and show correlations with the sensory characteristics
Phenols, flavors, and the Mediterranean Diet
No full textPhenols or phenolics are a class of compounds that have one or more hydroxyl groups attached to a 6-carbon aromatic ring, they occur as plant secondary metabolites, having in common the antioxidant activity. Their average daily intake varies widely around the world. Many researchers consider coffee, tea, wine, cocoa products, fruits and vegetables as the main sources of polyphenols in different diets. However, spices and culinary herbs have been referred to as the foods richest in polyphenols. Despite spices and culinary herbs are used in small amounts as seasonings, their contribution to the dietary supply of phytonutrients should not be disregarded. A diet rich in a variety of polyphenols (and other phytonutrients) has potential health benefits, namely in the prevention of chronic diseases and cancer. In addition, flavor and color are the most important factors for the selection of food by consumers. A multitude of endogenous food compounds, including phenolics, are involved in food flavor. The presence of phenolic compounds in the food matrix has been mainly associated with the perception of bitter taste and tactile sensation of astringency. However, these compounds can also impact the color and aroma notes of fruits and vegetables. Thus, understanding the sensory impact of these substances and relationships with consumers' approaches towards phenolic-rich fruits and vegetables may help find strategies to increase the consumption of such foods. A well-known example of a tasty, healthy and sustainable dietary model is the Mediterranean Diet. In this study, we summarize the dietary intake of some polyphenols from different dietary patterns around the world and the contribution of natural phenolic compounds to the flavor of food and beverages, in particularly those associated to the Mediterranean Diet.info:eu-repo/semantics/publishedVersio
Discrimination of some tunisian olive oil varieties according to their oxidative stability, volatiles compounds and chemometric analysis
No full textOxidation stability is a key property of olive oil quality and is affected by different antioxidant compounds whose levels may be influenced by several factors such as cultivar and place of production. Polyphenols, carotenoids, chlorophylls, fatty acids levels and some volatiles were correlated to oxidative stability in olive oils in five samples studied. Total polyphenols and saturated to polyunsaturated fatty acids (and/or oleic to linoleic acid ratio) ratio were shown to be the major parameters in oil antioxidant stability, according to analysis of variance and principal component analysis. The hexanal/E-2-hexenal ratio is a very important indicator of the freshness of the oils and can estimate their oxidation degre
Butylated Hydroxytoluene (BHT) emitted by fungi naturally occurring in olives during their pre-processing storage for improving olive oil stability
No full textExtra virgin olive oil is widely consumed because of its nutritional benefits and sensory properties which are very important to be preserved in the product. Therefore, chemically synthesized compounds, such as butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT), are widely used as antioxidants in oil products. It is well known that the activity of some micro-organisms able to oxidize free fatty acids can lead to the loss of the stability of the final product. Nevertheless, several researchers have been recently motivated to evaluate the potential of micro-organisms on the production of bioactive compounds. In this paper headspace solid micro-extraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS) were used for the characterization and investigation of Fungal Organic Volatile Metabolites (FOVCs) emitted by 14 fungal strains isolated from olives during their pre-processing storage. A wide range of volatile compounds were detected among them, Butylated Hydroxytoluene (BHT) was produced at levels ranging between 0.3 and 13.1%. This compound could be considered for the industry as natural antioxidant to substitute the synthetic ones used for ameliorating the stability of olive oil and other fatty food products.
Practical applications: As the pre-processing storage step is inevitable for several practical reasons, inducing the outgrowth of olive microflora (mainly fungi), which critically affect the physiological state of the fruit and thus the quality of the correspondent oil, this paper try to elucidate the potential of these naturally developing strains and their metabolites (FVOCs) of producing bioactive compounds mainly the Butylated Hydroxytoluene (BHT) which could be considered by the industry in order to substitute the synthetic one largely used to improve the stability of olive oil and other food products. Volatiles, when coupled with the power “omics” technologies represent a new frontier in bio-prospectin
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
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