1,721,053 research outputs found
Supercritical fluid extraction from microalgae with high content of LC-PUFAs. A case of study: Sc-CO2 oil extraction from Schizochytrium sp
No full textAmong the different kinds of marine sources, microalgae are a potential source of triacylglycerides which may contain high amounts of LC-PUFAs such as ω-3 fatty acids EPA and DHA. For the extraction of oil from microalgae, Sc-CO2 is regarded with interest being safer than hexane and offering a negligible environmental impact, a short extraction time and a petroleum-free final product. In such a contest, a mathematical model able to describe the kinetics of an SFE process was applied to the extraction with Sc-CO2 of lipids from Schizochytrium sp., a marine microalga characterized by a particularly high content of LC-PUFAs, and a very high concentration of DHA. The aim of this paper was to examine the effect of operating conditions on the kinetics of the SFE, on process yields and on the fatty acid composition of lipid extracts, also in comparison with the conventional extraction by percolation with n-hexane
The utilization of solid carbon dioxide in the extraction of extra-virgin olive oil.
No full textThe impact of the addition of solid CO2 on olive oil (EVOO/VOO) production in terms of extraction yield and chemical quality was studied at pilot scale in an industrial oil-press in two different crop seasons. The addition of CO2,s to the fruits induces the intracellular water freezing and the consequent laceration of cellular membranes could induce the diffusion of many cellular compounds. In the experimental conditions adopted, the addition of the cryogen to the olives during pre-milling phase greatly increased the extraction yield (ranging from ≅ 1 to ≅ 21 %), with respect to the related control.
Furthermore, the use of solid CO2 had no negative effects on chemical composition of the olive oil, maintaining the highest quality according to EU legal standards showed by control. Therefore, the utilization of solid CO2 as cryogen could be an appropriate technology to improve olive oil yield and quality and increase its shelf-life
Tecnologie produttive dei principali oli vegetali con particolare riferimento all'olio di palma
No full textTecnologie produttive dei principali oli vegetali con particolare riferimento all'olio di palm
Ad ogni vino il suo calice: dalla percezione al dato sperimentale
No full textMolti degustatori sono convinti che esista un bicchiere ottimale per ogni tipologia o stile di vino in assaggio. Tuttavia, rimane ancora irrisolto il quesito su quanto quest’idea sia scientificamente supportata dalle evidenze sperimentali o, al contrario, sia, piuttosto, il risultato di attività di marketing concertate da parte di alcuni produttori di calici.
Al fine di indagare l’influenza del calice sulla percezione del vino in assaggio, sei differenti calici disponibili in commercio sono stati impiegati da un panel composto da dieci degustatori addestrati, per caratterizzare da un punto di vista sensoriale uno stesso vino rosso strutturato, ottenuto con uveSangiovese e affinato in barriques. I profili sensoriali sono stati poi confrontati tra loro e con quello ottenuto per lo stesso vino mantenuto all’interno diun calice da degustazione standard. In questo modo, la classica correlazionecalice/vino è stata invertita, in quanto il vino è stato impiegato come strumento, mentre il reale oggetto di indagine è divenuto il calice.
Inoltre, al fine di mettere in evidenza se e quanto le differenze eventualmente riscontrate a livello organolettico nel vino dipendessero da differenze oggettive connesse con le differenti proprietà fisiche dei calici impiegati o se, al contrario fossero il risultato di impressioni personali e/o conoscenze pregresse dei componenti del panel, si è proceduto alla definizione del profilo emozionale suscitato dalle diverse forme geometriche proposte sia sullo stesso panel di degustatori esperti sia su un panel più numeroso costituito da consumatori comuni non addestrati
Il pane toscano a lievitazione naturale: un esempio dell'incontro tra tradizione e conoscenza
No full textIl pane toscano a lievitazione naturale viene tuttora prodotto a livello artigianale, seguendo tecniche di panificazione tradizionali che vengono tramandate di generazione in generazione e che prevedono l’impiego dell’impasto acido nella lavorazione di tutti i prodotti da forno. La madre acida, impiegata in panificazione, costituisce un esempio rappresentativo della stretta interazione che intercorre, negli alimenti fermentati, tra la tecnologia di produzione adottata (tempi, temperature e modalità con cui condurre i rinfreschi), lo sviluppo delle popolazioni microbiche interessate e le caratteristiche sensoriali enutrizionali del prodotto finito. Nel corso di una sperimentazione poliennale,effettuata presso la sezione di Tecnologie Alimentari del DiSAAA-a dell’Università di Pisa, in collaborazione con il Consorzio del pane toscano a lievitazione naturale, sono state valutate le caratteristiche composizionali e sensoriali di pani prodotti impiegando la stessa farina ma madri acide conservate a temperature diverse, con conseguente alterazione dell’equilibrio tra le popolazioni microbiche presenti (lieviti e batteri lattici) per determinare quali fossero i pani caratterizzati sia dal desiderato grado di lievitazione che da un adeguato contenuto acidico (in particolare acido lattico e acetico). È stato così possibile evidenziare l’esistenza di un alto grado di correlazione tra i dati composizionali che caratterizzavano la madre acida e le proprietà sensoriali dei pani corrispondenti e individuare la temperatura che, tra quelle testate, ha assicurato le migliori caratteristiche organolettiche al prodotto finito. Sono stati inoltre individuati i parametri biochimici (quoziente di fermentazione, pH e acidità titolabile; rapporto etanolo/acidi lattici) che possono essere utilmente impiegati nella tracciabilità del pane toscano e nella sua difesa dai «falsi» prodotti, eventualmente presenti sul mercato
A simplified method to estimate Sc-CO2 extraction of bioactive compounds from different matrices: Chili pepper vs. tomato by-products
Full text linkIn the last few decades, the search for bioactive compounds or "target molecules" from natural sources or their by-products has become the most important application of the supercritical fluid extraction (SFE) process. In this context, the present research had two main objectives: (i) to verify the effectiveness of a two-step SFE process (namely, a preliminary Sc-CO2 extraction of carotenoids followed by the recovery of polyphenols by ethanol coupled with Sc-CO2) in order to obtain bioactive extracts from two widespread different matrices (chili pepper and tomato by-products), and (ii) to test the validity of the mathematical model proposed to describe the kinetics of SFE of carotenoids from different matrices, the knowledge of which is required also for the definition of the role played in the extraction process by the characteristics of the sample matrix. On the basis of the results obtained, it was possible to introduce a simplified kinetic model that was able to describe the time evolution of the extraction of bioactive compounds (mainly carotenoids and phenols) from different substrates. In particular, while both chili pepper and tomato were confirmed to be good sources of bioactive antioxidant compounds, the extraction process from chili pepper was faster than from tomato under identical operating conditions
Effect of the baking process on artisanal sourdough bread-making: A technological and sensory evaluation.
Full text linkWhen used in optimized proportions, sourdough can improve volume, texture, flavour, and nutritional value of bread, and may increase the shelf life by retarding the staling process and protecting bread from mould and bacterial spoilage. In this context, the objective of the paper is double: a) to verify the influence of different baking procedures adopted by different artisanal bakeries on the sourdough composition and performance; b) to determine whether and how the operating conditions adopted can affect the chemical composition and the sensory characteristics of bread. The preliminary results indicate that chemical composition of sourdough and bread, as well as sensorial expression of corresponding bread, might be greatly influenced by the operating conditions adopted during baking. In particular, when the activity of hetero lactic bacteria was promoted (fermentation ratio FR @ 3.0), the bread showed the worst sensorial expression in terms of taste and structural characteristics of the crumb
Restoration of an old vineyard by replanting of missing vines: effects on grape production and wine quality
No full textThe viticultural and oenological characteristics of old and young Sangiovese vines were compared during a study set up by the Department of Agriculture, Food Environment (DAFE) in collaboration with an estate located at Cinigiano (GR), Italy, during two different vintages. Wines from each thesis were assessed for quality parameters and compared. The results show that the restoration of the vineyard, implemented by replacement of the missing vines, resulted in a quantitative and qualitative improvement over a decade. Indeed, the replanted vines were less vigorous and produced bunches of smaller size and with smaller grapes, which were characterized by a good phenolic endowment, especially for the anthocyanin component, which was also maintained in the wines
Primary and secondary shelf-life of bread as a function of formulation and MAP conditions: Focus on physical-chemical and sensory markers
No full textBread is one of the most widely consumed foods worldwide, and extending its shelf-life is a key concern for reducing waste, especially in light of the expected increase in the world population. This study aimed to assess how the bread formulation (flour, leavening agent) or storage conditions (modified atmosphere packaging (Air or Ar)) could influence its primary shelf-life (PSL) and secondary shelf-life (SSL), also determining possible physical, chemical and sensory markers. The results revealed that the choice of leavening agent had a significant effect on the PSL of bread, especially when combined with the gas used in the packaging. Compared to Air, Ar combined with sourdough slowed down weight loss and the staling process and allows bread to have a longer shelf-life, preserving its initial characteristics. The same synergistic effect was not observed for bread made with baker's yeast, suggesting the potential need of employing a different storage gas in the packaging. Indeed, for the SSL, the only effects detected are related to the leavening agents, where the sourdough exhibits a longer shelf-life compared to the baker’s yeast. These findings lead us to conclude that easily and quickly measurable parameters such as weight loss and water activity decrease, together with sensory analysis, can be used as markers to assess the PSL and SSL of bread
Influence of glass on the evaporation rate of wines
No full textAn experimental research was developed to individuate the possible correlations occurring among the evaporation rates of different wines (full-bodied red, rosé and white) and the geometrical parameters or their mathematical combinations of six different glasses. The results clearly evidenced the possibility to relate the evaporation rate of a wine with some dimensionless parameters deriving from the linear combination of the geometrical characteristics of the glasses. Moreover, it was possible to individuate a mathematical model relating the evaporation rates with the dimensionless parameters which could be usefully utilized to design new glasses able to enhance the evaporation rates of wines. This may enable consumers to fully perceive the "bouquet" of a wine, which represents a key component of its organoleptic qualities
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