1,720,967 research outputs found
The effect of UV irradiation on vitamin D2 content and antioxidant and antiglycation activities of mushrooms
Full text linkMushroom irradiation has been considered a sustainable process to generate high amounts of vitamin D2 due to the role of this vitamin for human health and of the global concerns regarding its deficient or inadequate intake. Mushrooms are also receiving increasing interest due to their nutritional and medicinal properties. However, there is still a knowledge gap regarding the effect of UV irradiation on mushroom bioactive compounds. In this study, two of the most cultivated mushroom species worldwide, Agaricus bisporus and Pleurotus ostreatus, were irradiated with UV-B, and the effect of processing was investigated on the contents of vitamin D2 as well as on antioxidant and antiglycation activities. UV irradiation increased vitamin D2 up to 57 μg/g d.w, which is an adequate level for the fortification of a number of target foods. UV irradiation decreased the antioxidant activity when measured by the Folin–Ciocalteu reagent, the 2,2-diphenyl-1-(2,4,6 trinitrophenyl) hydrazyl radical assay and the ferric ion-reducing antioxidant power assay, but did not decrease the mushroom’s ability to inhibit glycation of a target protein. These results open up a new area of investigation aimed at selecting mushroom species with high nutraceutical benefits for irradiation in order to maintain their potential properties to inhibit oxidative and glycation processes responsible for human diseases
Production of Functional Ingredients Using Bioactive Compounds from Pleurotus Ostreatus
No full textLe prime attività del progetto di tesi di dottorato sono descritte. In primo luogo, sono stati misurati i principali composti bioattivi di P. ostreatus, ovvero: β-glucani, ergosterolo, vitamina D2 e fenoli. Successivamente, è stata messa a punto una procedura di estrazione dei β-glucani misurando la resa e l'attività antiossidante. I β-glucani sono stati utilizzati come emulsionanti per l'incapsulamento di un composto ossidabile. La stabilità delle emulsioni olio-in-acqua (O/W) è stata determinata attraverso la variazione della distribuzione dimensionale delle gocce d’olio nel tempo. Il residuo di estrazione può essere utilizzato come fonte di ergosterolo e vitamina D2.The first activities of the PhD thesis project are described. Firstly, the major bioactive compounds of Pleurotus ostreatus, namely: β-glucans, ergosterol, vitamin D2 and phenolics were evaluated. Secondly, a food grade extraction procedure for the recovery of β-glucans was developed by measuring the yield and antioxidant activity. β-glucan-rich extract was used as emulsifying agent for the encapsulation of an oxidisable compound. The stability of oil-in-water (O/W) emulsions was determined checking the variation of oil droplets size distribution over time. The left-over insoluble solids could be exploited as a source of vitamin D2 and ergosterol
Production of stable emulsions using beta-glucans extracted from Pleurotus ostreatus to encapsulate oxidisable compounds
No full textThe basidiomycete Pleurotus ostreatus is a sustainable food source known to be rich in beta-glucans, functional compounds in mushrooms recognised for their numerous health, nutraceutical and physicochemical properties. The aim of the present study was to extract beta-glucans from P. ostreatus powder and to study the feasibility of using the extract to prepare oil-in-water emulsions formulated for the encapsulation of lipophilic antioxidants by spray drying e.g. with an oil droplet size about 2mm, a dry matter content of 40% w/w and with a physical stability of at least 2 h. Hot-water soluble beta-glucans fraction was extracted from P. ostreatus powder following a method adapted from Synytsya et al., (2009). Emulsions were prepared by rotor-stator homogenisation using maltodextrin DE12 as wall material, beta-glucans extract as emulsifier and commercial sunflower oil as a model for lipophilic active compounds. The emulsion stability was estimated from the evolution over time of the oil droplet size distribution measured by laser light diffraction. Extracts containing up to 27% w/w watersoluble beta-glucans were produced. Physically stable mono-modal emulsions were
obtained when MD/beta-glucans weight ratio was lower than about 500 to avoid depletion and beta-glucans/oil weight ratio was more than 0.014 to stabilize oil droplets. The usage of emulsifiers made-up by polymeric constituents with inherent bioactivity, such as mushroom beta-glucans, could be a sustainable and healthy alternative to common emulsifiers
Design of Functional Foods with New Ingredients from Pleurotus ostreatus Grown on Agri-Food Waste
No full textQuesto progetto di tesi di dottorato mira allo sviluppo di applicazioni della biomassa di Pleurotus ostreatus cresciuto su un substrato “sostenibile” nella produzione di alimenti a valore aggiunto. Nella prima fase, verranno definite le condizioni di trasformazione per la conversione di P. ostreatus coltivato sui sottoprodotti della vinificazione in due ingredienti alimentari: la biomassa totalmente essiccata e la frazione isolata di β-glucani, che verrà usata come incapsulante di un’emulsione olio-in-acqua contenente un target ossidabile. Nella seconda fase verranno studiate le applicazioni modello di questi ingredienti, allo scopo di mettere a punto delle puree vegetali arricchite in vitamina D2, β-glucani e un composto bioattivo ossidabile.This PhD project aims at the development of applications of Pleurotus ostreatus biomass grown on a “sustainable” substrate in the production of added-value foods. In the first step, the project will lead to the definition of processing conditions to convert P. ostreatus grown on winemaking by-products into two food ingredients: the totally dried whole biomass and the isolated β-glucan-rich fraction encapsulating an oil-in-water emulsion of an oxidisable target. In the second step, model applications of these ingredients will be studied aimed at the development of vegetable purees enriched in vitamin D2, β-glucans and an oxidisable bioactive compound
Kinetic study of vitamin D2 degradation in mushroom powder to improve its applications in fortified foods
No full textThe aim of this study was to develop a value chain approach to address the need for sustainable vitamin D-2 food sources. A combined process of UV-irradiation and air-drying was used to produce a Pleurotus ostreatus powder with a target amount of vitamin D-2 as an ingredient for functional foods. The kinetics of vitamin D-2 degradation was studied as a function of water activity (a(w)) in the range 0.11-0.75 at 30 degrees C, and temperature in the range 20-40 degrees C, at a(w) 0.32. The Guggenheim-Anderson-de Boer equation was applied to model experimental data of moisture content as a function of a(w) at 30 degrees C, and the resulting monolayer water activity was found to correspond to the a(w) level of 0.45. During storage under different environmental conditions, vitamin D-2 degradation followed first-order kinetics. The rate constants ranged from 0.00308 to 0.0121 d(1) at a(w) 0.11 and 0.75 at 30 degrees C, respectively. The Arrhenius equation was applied to calculate the activation energy for vitamin D-2 degradation at a(w) 0.32, which resulted 37.6 kJ/mol. The kinetics data obtained can be used as a basis to design the best formulation strategy to deliver this vitamin with functional foods
Assessing liking and food neophobia for vitamin D2 enriched breadsticks among school aged children
No full textVitamin D insufficiency is one of the most common micronutrient deficiency in young children worldwide and may lead to impaired neurodevelopment and rickets. Few foods naturally contain vitamin D and new fortified products need to be formulated considering hedonic responses and children satisfaction as main factors during product development. Among the sources of vitamin D, the edible mushroom Pleurotus ostreatus could be used as an innovative ingredient for food fortification, due to its interesting nutritional profile. Moreover, it could be also considered a sustainable food because of its ability to grow on agri-food wastes. This study was aimed at investigating children’ acceptance of five breadsticks samples added with increasing concentrations of P. ostreatus powder (from 0% to 8%) rich in vitamin D2. One hundred and three children (47 girls and 56 boys aged 9-11 years) were recruited and breadsticks liking was studied in relation to age, gender and neophobic traits. Results showed that sample without mushroom addiction obtained the highest liking score, while liking decreased with increasing concentration of P. ostreatus. However, all the modified breadsticks enriched in vitamin D2 were well accepted by the children. Generally, neophilic subjects gave higher liking scores compared to the neophobic ones, especially for the modified samples. The results of the present study interestingly suggest that it is possible to develop new vitamin D2 enriched formulations using an adequate concentration of mushroom powder to obtain acceptable food products by children. These fortified foods could be used as a natural and sustainable source of vitamin D2 to deal with the increasing deficiency of this micronutrient among children
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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