Francesca Venturi

Supercritical fluid extraction in sunflower seed technology

Sunflower (Helianthus annuus L.) seed represents an important source for edible oil and its protein fraction is also recognised as valuable for human consumption when suitably purified from polyphenols, which negatively affect colour and nutritional value. On this basis, a main research has been developed, with the aim of testing the technical feasibility of a supercritical fluid extraction (SFE) process involving a preliminary supercritical CO2 (SC-CO2) extraction of oil from sunflower de-hulled seeds, followed by the removal of polyphenols from de-fatted meal by means of ethanol coupled with SC-CO2. The paper reports the experimental protocol followed, together with the kinetics of the extractions, knowledge of which allows the optimisation of working parameters and the determination of process yields.

Development of Phenol-Enriched Olive Oil with Phenolic Compounds Extracted from Wastewater Produced by Physical Refining

While in the last few years the use of olive cake and mill wastewater as natural sources of phenolic compounds has been widely considered and several studies have focused on the development of new extraction methods and on the production of functional foods enriched with natural antioxidants, no data has been available on the production of a phenol-enriched refined olive oil with its own phenolic compounds extracted from wastewater produced during physical refining. In this study; we aimed to: (i) verify the effectiveness of a multi-step extraction process to recover the high-added-value phenolic compounds contained in wastewater derived from the preliminary washing degumming step of the physical refining of vegetal oils; (ii) evaluate their potential application for the stabilization of olive oil obtained with refined olive oils; and (iii) evaluate their antioxidant activity in an in vitro model of endothelial cells. The results obtained demonstrate the potential of using the refining wastewater as a source of bioactive compounds to improve the nutraceutical value as well as the antioxidant capacity of commercial olive oils. In the conditions adopted, the phenolic content significantly increased in the prototypes of phenol-enriched olive oils when compared with the control oil.

The kinetic effect of some wine components on the enzymatic hydrolysis of β-glucan.

Enzymatic preparations containing β-glucanases are utilised extensively in winemaking to facilitate the filtration of musts and wines coming from grapes affected by Botrytis cinerea, and to induce the release of mannoproteins and oligosaccharides from the cell walls of yeasts. The aim of the present work was to investigate the possible inhibitory effect of some wine components, and in particular of ethanol, on β-glucanase activities. For this purpose, the kinetic activity of a commercial enzymatic preparation containing β-glucanases was tested utilising both model solutions (buffer solution having a pH value similar to a must/wine with or without 13% v/v of ethanol added) and a red wine. When ethanol was added to the model solution, both the kinetic constant k and glucose production suffered a decrease of about 50% compared to the values detected in the absence of ethanol. A further loss of activity (about 87%) was found using red wine as reaction medium, suggesting, as already reported in the literature, that phenols could add their inhibitory effect to that of ethanol. The results obtained provide useful suggestions that can be adopted during winemaking. To promote the hydrolysis of the possible excess of β-glucan coming from grapes affected by Botritis cinerea, it would be more convenient to add β-glucanases before a significant amount of ethanol accumulates in the must/wine, while it is not possible to avoid the negative impact of ethanol or other possible inhibitors (phenols) to promote yeast degradation in wine left on lees.

Kinetics of D-glucose and D-fructose conversion during the alcoholic fermentation promoted by Saccharomyces cerevisiae.

Although many studies on the different aspects of alcoholic fermentation are available in the literature, it is still difficult to identify the possible causes of the slowing-down or stuck of fermentations, even if the change of some compositional parameters (D-glucose/D-fructose and glycerine produced/hexoses converted ratios) could be assumed as sound signals of a possible deviation from the usual Saccharomyces metabolic pathways. The reason why alcoholic yeasts preferably metabolise D-glucose rather than D-fructose was investigated by a kinetic model based on six functional parameters having a well-defined chemical-physical meaning. The time evolution of different initial concentrations of D-glucose and D-fructose, dissolved in a model solution simulating a must (citrate buffer at pH 3.4 inoculated by a commercial strain of Saccharomyces cerevisiae), was investigated adding or not ethanol to the reaction medium. When a reduced amount of ethanol was dissolved in the reaction medium, the time evolution of the fermentation rates of these two sugars did not differ significantly, to diversify rather strongly when the alcoholic concentration increased. The hypothesised mathematical model accounts for this particular kinetic behaviour. In fact, only the sensitivity to ethanol showed by the enzymatic protein involved in the limiting steps of the fermentation process of these two sugars differed significantly, the enzymatic transformation of D-fructose being more sensitive to ethanol than D-glucose. This difference was able to justify the different kinetic behaviours shown by the two sugars when ethanol concentration in the reaction medium increased.

The expression of a full-bodied red wine as a function of the characteristics of the glass utilized for the tasting

With the aim to better understand how the differences related to the glass type can influence the consumer perception of the wine, the same product was assessed in each glass, at the same moment, for three times (t = 0, 40 and 120 min) during every tasting session. The evolution of wine in each glass was characterized also by a chemical and physical point of view, in order to verify if the different characteristics of the glasses utilized influenced the chemical parameters analyzed, so to justify the changes in the sensorial perception expressed by the panel components. Thanks to the general overlapping between the developments related to the evolution of sensorial, chemical and physical characteristics of the wine, it was possible to define a final classification of the types of glasses utilized and identify which glass seemed to show the best influence on the sensory perceptions of the wine tasted.

Glass and wine: a good example of the deep relationship between drinkware and beverage

ABSTRACT As the choice of the drinkware could deeply affect consumer perception during beverage consumption, an experimental research was carried out by expert testers to investigate the evolution of chemical–physical and sensory profiles of a typical rosé wine maintained in different types of glasses. The aim of this research was to select some parameters to well correlate beverage sensory properties with glass characteristics which can be used for drinkware design. The different sensorial profiles, obtained as a function of the geometric characteristics of glasses, were compared with one another. In order to find any significant parameter useful to represent the time evolution of the wine inside each vessel, the wine poured in all glasses was also characterized at different times from a chemical and physical point of view. As the design parameters are now guided more by aesthetic reasons rather than by functional ones, this new ‘integrated approach’, deriving from the merging of chemical, physical and sensorial data, can be used to design the optimum vessel for the enjoyment of the consumer during assessing sessions. This innovative procedure could be easily adapted for every beverage such as fruit juices, sparkling wines or beer.

The Kinetics of Alcoholic Fermentation by Two Yeast Strains in High Sugar Concentration Media

Over the last two decades, most of Italian vines have produced grapes with higher sugar to total acid ratios, greater concentrations of phenols and aromatic compounds and greater potential wine quality. As a consequence, the musts obtained by these grapes are more difficult to process because of the risk of slowing or stuck of fermentation. With the aim of describing the time evolution of the sugars bioconversion during alcoholic fermentation, the kinetics of the D-glucose and D-fructose degradations, promoted by two yeast strains (Saccharomyces cerevisiae (strain C) e Saccharomyces bayanus (strain B)), was investigated using synthetic media, added or not with ethanol. The concentrations of both the substrates and the products of the sugars conversions, as well as the number of viable cells of yeasts, were determined as a function of the alcoholic fermentation time and the related kinetics constants determined. If the reaction medium contained high concentrations of both glucose and fructose, the strains showed significant different fermentatory ability. In these conditions a stuck of fermentation occurred and the remaining sugar was only fructose (strain C) or prevailing fructose (strain B). If the reaction medium contained only glucose as substrate, the strain C seemed more efficient while the kinetics behavior changed completely in presence of only fructose. On the basis of the information collected using this kinetic approach, it would be possible to develop technical data sheets, specific for each yeast strain, useful to choose the optimal microbial strain as a function of the different operative conditions. Moreover the kinetic constant of hexose conversion could be adopted as bio-markers in selection and breeding of wine yeast strains having a lower tendency for sluggish fructose fermentation.

Shaping food systems towards improved nutrition: a case study on Tuscan Bread Protected Designation of Origin

The concern for the quality of food, its composition and contribution towards nutrition and health is widespread among public and private food system actors. The increasing interest in locally integrated supply chains leads to reconsider the configuration of the food system in relation to sustainability and health outcomes. This article focuses on the relationship between processing practices and nutritional value in the wheat-tobread sector, illustrated by a case study on the Tuscan Bread Protected Designation of Origin (PDO). By adopting a food system perspective, the case study shows how the different actors have mobilized to respond to multiple drivers of change. A mixed research method approach is adopted to illustrate the relationship between processing practices and nutritional value outcomes: practice-based indicators for each step of the chain are complemented with performance-based indicators of the chemical, physical and sensorial profile of Tuscan Bread PDO. Furthermore, the implications on fo...

A kinetic method to identify the optimum temperature for β-glucanase activity.

Enzymatic preparations containing β-glucanases are largely utilised in winemaking to facilitate the filtration of musts and wines coming from grapes affected by Botrytis cinerea, and to induce the release of mannoproteins and oligosaccharides from the cell wall of yeasts. The aim of the present work was to investigate the effect of temperature on β-glucanase activity. For this purpose, the kinetic activity of a commercial enzymatic preparation containing β-glucanases was tested utilising a model solution (buffer solution of β-glucan extracted from alcoholic yeasts with a pH similar to a must/wine, with or without 13% ethanol added) at different temperatures ranging from 20 to 40°C. By an innovative procedure based on a kinetic model able to describe the time evolution of D-glucose accumulation – the final product of β-glucan hydrolysis – it was possible to relate the maximum rate of this process to temperature. The temperature at which the enzymatic activity showed the maximum value (Tmax) was close to 30°C, without any substantial variation following ethanol addition. Indeed, in spite of a remarkable reduction (of about 66%) in the catalytic activity shown by the commercial enzymatic preparation, no significant variation of the Tmax was observed, suggesting that the presence of an inhibitor such as ethanol in the reaction medium did not change the sensibility of the enzymes to temperature.

The Kinetics of Fermentations in Sourdough Bread Stored at Different Temperature and Influence on Bread Quality

The fermentations induced by the utilization of sourdough in bread-making, are able to enhance the qualitative properties of the final dough, improving its volume, texture and flavor, so to obtain a bread characterized by high qualitative properties and able to retard its staling process. In particular the working conditions adopted can deeply affect the ratio occurring between the populations of lactic acid bacteria and alcoholic yeasts of the sourdough and then also the productions of the related metabolites, which deeply affect the organoleptic characteristics and then also the quality of the final bread. The effect induced on the microbial and chemical composition of the sourdough by different values of the storage temperature utilized (13, 19 and 27°C) between two successive refreshes (~ 24 hours), was evaluated to put in evidence the different sensory characteristics assumed by the corresponding breads. The sensory profiles of the obtained breads evaluated by the descriptive analyses, were carried on by a panel of trained assessors using a sensorial sheet specifically developed for this purpose and characterized by unstructured graphical intensity scales; the reliability of judgments obtained was evaluated by statistical analysis.