PHASE CHANGE UNDER STATIC ELECTRICAL FIELD; IN THE CASE OF LIPIDS

International audiencePhase change in biological tissues may be affected by electrical and magnetic disturbances. Freezing under static electric field of water, aqueous solution and pork meat has been investigated by the authors, showing the ability of this process to refine ice crystals in frozen matrices. SEF affects the supercooling, which is usually reduced with SEF. SEF also triggers the nucleation. The use of radiofrequencies and microwaves has also been used recently by researchers to promote refined ice crystallization in food systems. A focus is proposed on recent experiments done on solidification of a vegetable fat mix (Vegetaline ® – France) under static electric field (SEF). Results showed that SEF affects the supercooling and the phase change temperature of the fat mix indicating a possible impact on the crystalline structure of the solidified fat

Bolus rheology and ease of swallowing of particulated semi-solid foods as evaluated by an elderly panel

Preparation of a bolus is a complex process with both food comminution and degree of lubrication with saliva playing an important role in a safe swallow. Swallowing disorders i.e. dysphagia, are especially present among the elderly population and often lead to choking and further health complications. The aim of this research was to investigate the relationship between the perception of ease of swallowing in the elderly and the rheological parameters of particulated foods, using broccoli purees as a model system. Particulated foods can be described as a concentrated dispersion of plant particles in a fluid phase. The effect of the fluid phase (Newtonian vs. shear thinning) and dispersed phase (plant particles with different size distribution and morphology) on the rheological properties of simulated boli was studied by characterising shear viscosity, viscoelasticity, yield stress, extensional viscosity and cohesiveness. Ease of swallowing and mouthfeel were evaluated by a semi trained healthy elderly panel (n = 19, aged 61 to 81). Ease of swallowing was correlated with the presence of yield stress and extensional viscosity in the bolus, characteristic of boli with xanthan gum as the fluid phase. Although the properties of the fluid phase played a dominant role in the ease of swallowing, compared to the dispersed phase, both components played a role in the rheological properties of the bolus and the perception of ease of swallowing by the elderly panel. These results provide insights into the design of personalised foods for populations with specific needs such as those suffering from swallowing disorders

From winery waste to bioactive compounds and new polymeric biocomposites: a contribution to the circular economy concept

The paper aims at optimising and validating possible routes toward the full valorisation of grape agrowaste to produce bioactive molecules and new materials. Starting from Merlot red pomace, phenol complex mixtures were successfully extracted by using two different approaches. Extracts obtained by solvent-based (SE) technique contained up to 46.9 gGAeq/kgDW of total phenols. Depending on the used solvent, the prevalence of compounds belonging to different phenol families was achieved. Pressurized liquid extraction (PLE) gave higher total phenol yields (up to 79 gGAeq/kgDW) but a lower range of extracted compounds. All liquid extracts exerted strong antioxidant properties. Moreover, both SE and PLE extraction solid residues were directly exploited (between 5 and 20% w/w) to prepare biocomposite materials by direct mixing via an eco-friendly approach with PHBV polymer. The final composites showed mechanical characteristics similar to PHVB matrix. The use of pomace residues in biocomposites could therefore bring both to the reduction of the cost of the final material, as a lower amount of costly PHBV is used. The present research demonstrated the full valorisation of grape pomace, an agrowaste produced every year in large amounts and having a significant environmental impact

COLDμWAVE_Microwave blanching equipment

Design and description of the prototype MW blanching laboratory equipmen

Microwave assisted freezing equipment

Image representing the equipment used for microwave assisted freezing during the implementation of COLDμWAVE project

Enzymatic transformation of compounds content in Mastic Gum and Mastic oil

In the current dissertation, the biotechnological modification of perillyl alcohol, which is a compound of the essential oil of Chios mastic gum, was studied. For the biotransformations of the specific substance biocatalytical methods were developed. These methods were based on the use of hydrolytic enzymes like glucosidases and lipases in non conventional media such as organic solvents, biphasic and solvent free systems. The volatile compound which was chosen to be used in the current dissertation was perillyl alcohol since after a series of studies it is considered to have a significant anticarcinogenic activity. Perillyl alcohol is a primary monoterpenol which is produced as a hydroxylated metabolite of D-limonene in the secondary metabolism of several plant species. By means of biocatalytical processes in non conventional media the selective transformation of perillyl alcohol was carried out. The enzymatic modifications which were carried out to the molecule of perillyl alcohol led to the synthesis of new analogues with altered physicochemical properties. More specifically the synthesis of an analogue with increased polarity such as perillyl β-D-glucopyranoside was carried out through selective glucosylation. Moreover, the further modification of the glucoside which was achieved through enzymatic acylation with a saturated fatty acid led to the synthesis of an amphiphilic molecule. During this study the esterification of perillyl alcohol with several dicarboxylic acids as well as its further linking with D-(+)-glucose molecule were carried out. In order to optimize the procedure of the synthesis of the new analogues, the influence of several reaction parameters was studied. Concerning the synthesis of the esters of perillyl alcohol with dicarboxylic acids, the optimization of the method was carried out using a Response Surface Methodology prediction model. All the new analogues of perillyl alcohol which were synthesized during this dissertation were identified by analyzing the corresponding NMR and LC-MS/MS spectra. Furthermore, there was an attempt to investigate the influence of these modifications in the biological activity in comparison with the native molecule. Those preliminary tests included the influence of the modified molecules in the cell proliferation of Lewis lung carcinoma (LLC) cells and the influence on the chymotrypsin-like activity of the 20S complex of the proteasome on embryonic human lung fibroblasts (HFL-1)Στην παρούσα διδακτορική διατριβή μελετήθηκε η βιοτεχνολογική τροποποίηση της περιλλυλ-αλκοόλης που αποτελεί συστατικό του αιθέριου ελαίου της μαστίχας Χίου. Για τη βιομετατροπή του συγκεκριμένου συστατικού αναπτύχθηκαν βιοκαταλυτικές μέθοδοι που βασίστηκαν στη χρήση υδρολυτικών ενζύμων, όπως οι γλυκοζιδάσες και οι λιπάσες, σε μη συμβατικά μέσα, όπως οργανικοί διαλύτες, διφασικά συστήματα και συστήματα «ελεύθερα διαλύτη». Το αρωματικό συστατικό το οποίο επιλέχθηκε να χρησιμοποιηθεί στην παρούσα εργασία ήταν η περιλλυλ-αλκοόλη, αφού από διάφορες μελέτες που έχουν πραγματοποιηθεί θεωρείται πως έχει σημαντική αντικαρκινική δράση. Η περιλλυλ-αλκοόλη είναι μία πρωτοταγής μονοτερπενόλη. Με τη χρήση βιοκαταλυτικών μεθόδων σε μη συμβατικά μέσα επιτεύχθηκε η εκλεκτική τροποποίηση της περιλλυλ-αλκοόλης. Οι ενζυμικές τροποποιήσεις που επιχειρήθηκαν στο μόριο της περιλλυλ-αλκοόλης, οδήγησαν στη σύνθεση νέων ενώσεων με τροποποιημένες φυσικοχημικές ιδιότητες. Πιο συγκεκριμένα, πραγματοποιήθηκε η σύνθεση ενός αναλόγου με αυξημένη πολικότητα όπως ο περιλλυλ-β-D γλυκοπυρανοζίτης μέσω εκλεκτικής γλυκοζυλίωσης. Ενώ, η περαιτέρω τροποποίηση του γλυκοζίτη που πραγματοποιήθηκε μέσω ενζυμικής ακυλίωσης με ένα κορεσμένο λιπαρό οξύ οδήγησε στη σύνθεση ενός αμφίφιλου μορίου. Στα πλαίσια της σύνθεσης νέων αναλόγων της περιλλυλ-αλκοόλης, επιχειρήθηκε η εστεροποίησή της με διάφορα δικαρβοξυλικά οξέα καθώς και η περαιτέρω σύζευξή της με ένα μόριο D-(+)-γλυκόζης. Με σκοπό τη βελτιστοποίηση των μεθόδων σύνθεσης των νέων αναλόγων, πραγματοποιήθηκε μελέτη των διάφορων παραμέτρων που επηρεάζουν τις ενζυμικές αντιδράσεις. Σε όλα τα νέα ανάλογα της περιλλυλ-αλκοόλης που συντέθηκαν ταυτοποιήθηκε η χημική τους δομή με ανάλυση φασμάτων φασματομετρίας μάζας (LC-MS/MS) παράλληλα με την ανάλυση μονοδιάστατων και δισδιάστατων φασμάτων πυρηνικού μαγνητικού συντονισμού (NMR). Τέλος, σε όλα τα νέα ανάλογα της περιλλυλ-αλκοόλης που συντέθηκαν στα πλαίσια της διατριβής επιχειρήθηκε μία ενδεικτική μελέτη αναφορικά με την επίδραση των τροποποιήσεων στη βιολογική δράση συγκριτικά με το αρχικό μόριο. Τα προκαταρτικά πειράματα που πραγματοποιήθηκαν αφορούσαν την επίδραση που είχαν η τροποποιήσεις στον πολλαπλασιασμό των κυττάρων από αδενοκαρκίνωμα πνεύμονα ποντικιού (LLC), αλλά και στην ενεργότητα τύπου χυμοθρυψίνης του 20S συμπλόκου του πρωτεοσώματος σε κύτταρα από φυσιολογικούς εμβρυϊκούς ανθρώπινους ινοβλάστες πνεύμονα (HFL-1

Water/ice transitions and food quality

International audienc

Impact of heating operations on the microbial ecology of foods

There are several drawbacks of heat processes as their application may also lead to nutritional and quality deterioration of the food product. The chapter presents basic information regarding the heating processes and unit operations and covers the impact of these operations on food-borne microorganisms. It describes the main cooking methods, such as grilling, broiling, and roasting. Quantitative methodologies are the main tools to describe the impact of a process as well as the storage conditions post-processing on the food stability. In order to assess the efficacy of a specific processing technology, the estimation of the time to achieve a certain number of log reductions can be applied. The most common process in the food industry is the thermal process. The chapter reviews a number of different thermal processes and outlines critical issues in relation to their efficacy and to their impact on the microbial inactivation

Congélation de viande de porc sous champ électrique : effet sur la taille et la structure des cristaux de glace

A static electric field is expected to modify the orientation of polar molecules such as water. This paper presents original results obtained in the case of freezing of pork meat (filet mignon) under static electric field using a lab scale miniature freezer. A control sample has been compared to meat frozen with 12 kV electric field (approx. 6·103 kV/m). The degree of supercooling during freezing was reduced with increasing static electric field; values of 3.93 ± 1.3°C and 1.92 ± 1.45°C were observed for the control and the sample frozen at 12 kV respectively. The average size of the ice crystals was significantly reduced with increasing electric field; values of 32.79 ± 4.04 µm and 14.55 ± 8.20 µm were observed for the control and the sample frozen at 12 kV respectively. These original results demonstrate clearly the advantage of freezing under static electric field which appears as a promising and innovative freezing process