1,720,989 research outputs found
An Overview on the Presence of Cyclopropane Fatty Acids in Milk and Dairy Products
No full textA survey was carried out to determine the presence of cyclopropane fatty acids (CPFA) in various dairy products. CPFA such as lactobacillic acid and dihydrosterculic acid are components of bacterial membranes and have been recently detected in milk from cows fed with maize silage. In this paper about 200 dairy samples comprising cow, sheep, and goat milk, cheese, yogurt/fermented milk, and butter were analyzed. Results showed that cow milks were generally positive to CPFA (0.014-0.105% of total fatty acids), while goat, yak, and sheep milks were negative. Experimental yogurt and fermented milks showed the same CPFA content of the starting milk. Positive to CPFA were also the majority of samples of commercial butter and cheeses, except some PDO cheeses as Parmigiano-Reggiano and Fontina, cheeses from mountain regions, and goat and sheep cheeses. These data suggest that the presence of CPFA in dairy products could be used as a marker of silage feeding
Presence and variation of gamma-aminobutyric acid and other free amino acids in cocoa beans from different geographical origins
No full textgamma-Aminobutyric acid (GABA) is a non-protein amino acid coming from the enzymatic alpha-decarboxylation of glutamate. It is a neurotransmitter that has recently raised some interests for its health effects: hypotensive, diuretic, tranquilizer and diabetes preventing agent. Regarding GABA content in cocoa, rare information is available in literature, so the aim of this study was to provide an overview on the GABA content in fermented and dried cocoa beans from different geographical origins (Africa, Central/South America, Asia and Oceania). GABA and other free amino acids were analyzed by HPLC/FLD after derivatization with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate. Results showed that cocoa beans are an excellent source of GABA and its content is extremely variable as a function of the geographical origin, ranging from a minimum of 31.7 mg/100 g for Grenada beans to a maximum of 101.2 mg/100 g for Ecuador beans
GC-MS profiling of minor components in nuts: Determination of simple phenols, indole derivatives and phytoestrogens (lignans)
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Geographical origin discrimination of Pistachio (Pistacia vera L.) through combined analysis of physical and chemical features
No full textA physicochemical assessment was carried out to discriminate the geographical origin of pistachio (Pistacia vera L.) following the regulation relative to the protection of geographical indications and designations of origin for agricultural products and foodstuffs (Article 4, paragraph 2 of Regulation (EC) No. 510/2006). One-way ANOVA results revealed that all the physical features were significantly (p ≤ 0.05) affected by the geographical origin, while chlorophyll a/chlorophyll b and two fatty acids [heptadecenoic acid (C17:1) and behenic (C22)] did not show significant (p > 0.05) differences among the different geographical origins. However, the remaining fatty acids showed significant (p ≤ 0.05) differences between pistachios coming from different countries (Iran, USA, Turkey, Syria, Kyrgyzstan and Italy) as well as between pistachios coming from two Italian locations (Bronte and Agrigento). Principal component analysis enabled to highlight differences among pistachios from different countries, and partial least squares enabled a better discrimination among pistachios from well-defined geographic areas, such as Bronte pistachios. Therefore, combining physicochemical features can be a valid tool for geographical origin discrimination of pistachio
Extraction, identification and semi-quantification of oligopeptides in cocoa beans
No full textPeptides and amino acids generated during cocoa bean fermentation are known to be the most important precursors for the development of cocoa aroma. Although cocoa fermentation and aroma development have been extensively studied, the cocoa oligopeptide fraction is under-investigated. In particular, the identification of specific peptide sequences and the quantification of cocoa peptides are scarce in the literature. The aim of this study was to investigate the presence of oligopeptides in fermented cocoa beans. Peptides were analysed by reversed phase LC/ESI-MS and LC/ESI-MS/MS, and the molecular masses of 44 different peptides were obtained by analysing the mass spectra associated with the most intense chromatographic peaks. Peptides were identified based on the exact molecular masses, mass fragmentation patterns and by comparison with vicilin and 21 kDa cocoa seed protein sequences. Semi-quantitative data on peptide presence in fermented cocoa samples of different geographic origin, different fermentation levels and on roasted products were also provided
Cyclopropyl and ω-cyclohexyl fatty acids as quality markers of cow milk and cheese
Full text linkContent of cyclopropyl and ω-cyclohexyl fatty acids of microbial origin, respectively, from silage and rumen, was determined by GC–MS and confirmed by 1H NMR in more than 200 milk samples from dairy cows fed with different forages. Cyclopropyl fatty acids (about 0.1% of milk fat) were detected for the first time in milk and they were present only in milk samples from cows fed with forages containing maize silage, which is not allowed to produce milk for some PDO cheeses as Parmigiano-Reggiano. Their determination can be proposed as a quality parameter of milk or feed and it can be useful especially to distinguish cheeses sold as Parmigiano Reggiano from others cheeses. The content of ω-cyclohexyl tridecanoic acid varied from 0.0% to 0.15% of milk fat, and it was higher in milk samples from cows fed with diets richer in cereal meal
Development of protein-bound and free D-amino acids during processing of cocoa beans to chocolate
No full textDevelopment of a Quantitative GC-MS Method for the Detection of Cyclopropane Fatty Acids in Cheese as New Molecular Markers for Parmigiano Reggiano Authentication
No full textCyclopropane fatty acids (CPFA), as lactobacillic acid and dihydrosterculic acid, are components of bacterial membranes and have been recently detected in milk and in dairy products from cows fed with corn silage. In this paper, a specific quantitative gas chromatography-mass spectrometry (GC-MS) method for the detection of CPFA in cheeses was developed, and the quality parameters of the method (limit of detection, limit of quantitation, and intralaboratory precision) were assessed. Limit of detection and quantitation of CPFA were, respectively, 60 and 200 mg/kg of cheese fat, and the intralaboratory precision, determined on three concentration levels, satisfied the Horwitz equation. This method was applied to 304 samples of PDO cheeses of certified origin, including Parmigiano Reggiano (Italy), Grana Padano (Italy), Fontina (Italy), Comté (France), and Gruyère (Switzerland). Results showed that CPFA were absent in all of the cheeses whose Production Specification Rules expressly forbid the use of silages (Parmigiano Reggiano, Fontina, Comté, and Gruyère). CPFA were instead present in variable concentrations (300-830 mg/kg of fat) in all of the samples of Grana Padano cheese (silages admitted). A mix of grated Parmigiano Reggiano and Grana Padano was also prepared, showing that the method is able to detect the counterfeiting of Parmigiano Reggiano with other cheeses up to 10-20% Grana Padano content. These results support the hypothesis that CPFA can be used as a marker of silage feedings for cheeses, and the data reported can be considered a first attempt to create a database for CPFA presence in PDO cheeses
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
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