Development of a citrus peel waste biorefinery for the production of high added-value commodities and biofuels

Citrus fruits constitute one of the most highly utilized food products worldwide. The production of citrus fruits reaches over 124×106 t per year, while citrus juice manufacturing generates 25×106 t. During the processing of the fruit, half of its mass is converted into citrus peel waste (CPW) consisting of peels, seeds and segment membranes. Current management practices include the use of CPW as animal feed or disposal in landfills. However, CPW is composed of pectin, cellulose, hemicellulose, soluble sugars and essential oils, components that constitute CPW as a promising feedstock for extraction and production of addedvalue products and biofuels through the biorefinery platform. The proposed biorefinery of this work combines physicochemical and biological treatments for extraction of essential oils and pectin as well as for production of succinic acid (platform chemical), ethanol and methane (biofuels) and a fertilizer. The first step employed distillation for extraction and collection of essential oils where the yield reached 0.43% and 0.24% (v/w) for “Mandora” and household citrus waste respectively. The next step of the proposed biorefinery included acid hydrolysis, where the optimized conditions comprised 116 oC for 10 min using 5% (w/v) of dry raw material for both materials. Afterwards, the extraction of pectin, which reached 30.5% (w/w), was separated from the hydrolyzate generated through addition of ethanol. Subsequently, following ethanol removal, the hydrolyzate was microbially fermented to succinic acid or ethanol. Succinic acid production was enhanced with the addition of corn steep liquor in fermentations, while the addition of vitamins increased the production rate. A fed-batch experiment was also conducted and resulted in slight increase of both the final concentration of succinic acid as well as the product yield. Moreover, ethanol production was studied using P. kudriavzevii KVMP10, a newly thermotolerant yeast which was compared against two major industrial yeasts (S. cerevisiae and K. marxianus) and found to be a more efficient ethanol producer through use of CPW hydrolyzates. Finally, solid biorefinery residues were tested in anaerobic digestion for the production of biomethane and in agricultural applications as fertilizer targeting the development of a zero-waste process.Vasilleios Fotopoulos, Emeritus Emmanuel M. PapamichaelComplete

Executive functions: Sex differences in patients with Mild Cognitive Impairment and Dementia due to Alzheimer’s disease.

Τα τελευταία χρόνια οι διαφορές φύλου στη νόηση ερευνώνται όλο και πιο επιστάμενα. Αν και πολλές έρευνες αναφέρουν ενδιαφέροντα αποτελέσματα, οι περισσότερες έρευνες επικεντρώνονται σε λεκτικές και οπτικο-χωρικές δοκιμασίες. Έχει λοιπόν, αποδειχτεί ότι οι άνδρες τα πηγαίνουν καλύτερα σε οπτικο-χωρικές δοκιμασίες και οι γυναίκες τα πηγαίνουν καλύτερα σε λεκτικές δοκιμασίες. Οι διαφορές φύλου στις επιτελικές δοκιμασίες δεν έχουν μελετηθεί αρκετά, πιθανότατα λόγω της περίπλοκης φύσης του γνωστικού αυτού τομέα. Επίσης, οι διαφορές φύλου στις νευροεκφυλιστικές ασθένειες έχουν μελετηθεί, χωρίς όμως το επίκεντρο να είναι η επίδραση του φύλου στην νοητική έκπτωση. Στην παρούσα έρευνα, ένα δείγμα 198 ασθενών συλλέχθηκε και χωρίστηκε σε δύο ομάδες ανάλογα με τη διάγνωση. Η ομάδα των ασθενών με Ήπια Νοητική Έκπτωση (ΗΝΕ) είχε 69 άνδρες και 49 γυναίκες και η ομάδα των ασθενών με άνοια λόγω νόσου Αλτσχάιμερ (ΝΑ) είχε 50 άνδρες και 30 γυναίκες. Σε κάθε διαγνωστική ομάδα ξεχωριστά, εξετάστηκε η επίδοση των ανδρών σε αντιδιαστολή με την επίδοση των γυναικών σε επτά νευροψυχολογικές δοκιμασίες, που εξετάζουν επιτελικές λειτουργίες. Τα αποτελέσματα της παρούσας έρευνας δεν συμφωνούν με ευρήματα προηγούμενων ερευνών σε υγιή υποκείμενα. Στην ομάδα των ασθενών με ΗΝΕ, οι γυναίκες είχαν καλύτερες επιδόσεις από τους άνδρες στη δοκιμασία της φωνημικής λεκτικής ροής, ενώ στην ομάδα των ασθενών με ΝΑ οι άνδρες είχαν καλύτερες επιδόσεις από τις γυναίκες στο συνολικό σκορ της Frontal Assessment Battery και στην επιμέρους δοκιμασίας της συστοιχίας με όνομα Go-No-Go. Οι συνέπειες των αποτελεσμάτων αλλά και οι περιορισμοί της παρούσας έρευνας αναλύονται. Εν κατακλείδι, το ακριβές προφίλ νοητικής έκπτωσης σε άνδρες και γυναίκες πρέπει να διερευνηθεί, καθώς μπορεί να οδηγήσει στην καλύτερη κατανόηση των νευροεκφυλιστικών ασθενειών. Αυτό με τη σειρά του, μπορεί να συμβάλει σε πιο έγκαιρη διάγνωση και παρέμβαση ενισχύοντας έτσι την ποιότητα ζωής ασθενών και των δύο φύλων.Sex differences in cognition are being studied more thoroughly in recent years. Whilst, many studies have reported interesting results, most of them have been focusing on verbal and spatial tasks. It has long been established that males are better at spatial tasks and females are better at verbal tasks. Not much research has been done into sex differences in executive functions, probably because it is a very complex cognitive domain. In addition, differences between the two sexes have been reported in neurodegenerative diseases, although how sex influences cognitive decline has not been investigated by many. In the present study a total of 198 patients were included and divided into two groups depending on their diagnosis. The group of patients with Mild Cognitive Impairment (MCI) consisted of 69 males and 49 females and the group of patients with dementia due to Alzheimer’s disease (ADD) consisted of 50 males and 30 females. In each diagnostic group separately, we compared the performance of males against that of females in seven neuropsychological tools that test executive functions. Our results are not in complete agreement with previous studies of healthy individuals. In the MCI group, females performed better than males at a task of Phonemic Fluency and in the ADD group, males performed better than females at the total score of the Frontal Assessment Battery and in its sixth subscale named Go-No-Go. The implications of these results are discussed as well as the limitations of the current study. In conclusion, the exact pattern of cognitive decline in males and females should be investigated as it can give us a better understanding of the neurodegenerative diseases. Also, that could lead to an earlier diagnosis and consequently earlier intervention that could enhance quality of life of patients of both sexes

High temperature alcoholic fermentation of orange peel by the newly isolated thermotolerant Pichia kudriavzevii KVMP10

This work explores the potential for the development of orange peel based ethanol bioprocesses through isolation of the thermotolerant Pichia kudriavzevii KVMP10. A model solution of hydrolysed Valencia orange peel was employed to determine the ethanologenic potential of the yeast, which was maximized at 42°C producing 54 g l-1 of ethanol. The effect of orange peel oil on bioethanol formation was investigated at 30 and 42°C confirming that the minimum inhibitory peel oil content was 0.01% (v/v). Pichia kudriavzevii KVMP10 demonstrated significant technological advantages for the production of sustainable bioenergy, such as utilization of both hexoses (glucose, sucrose, fructose and galactose) and pentoses (xylose) at high temperatures, exemplifying its great potential for application in orange peel based biorefineries for ethanol production

A biorefinery for conversion of citrus peel waste into essential oils, pectin, fertilizer and succinic acid via different fermentation strategies

A process for the valorization of citrus peel waste (CPW) has been developed aiming to produce succinic acid and a series of added-value products through the biorefinery platform. CPW was subject to physicochemical and biological treatment to isolate essential oils (0.43%) and pectin (30.53%) as extractable products, pretreating the material for subsequent production of succinic acid that enabled application of remaining biorefinery residues (BR) as fertilizer substitute. Cellulose, hemicellulose and lignin contents of CPW accounted for 22.45%, 8.05% and 0.66% respectively, while acid hydrolysis reduced hemicellulose by 3.42% in BR. Moreover, essential oils extracted from CPW included 17 compounds, among which D-limonene reached 96.7%. The hydrolyzate generated was fermented for succinic acid production using Actinobacillus succinogenes. Different batch experiments demonstrated that the combined use of corn steep liquor (CSL) and vitamins in a lab-scale bioreactor resulted in product concentration and yield that reached 18.5 g L−1 and 0.62 g g−1 respectively. Although simultaneous saccharification and fermentation (SSF) could not enhance succinic acid production, a fed-batch fermentation strategy increased succinic acid concentration and yield generating 22.4 g L−1 and 0.73 g g−1 respectively, while the mass of the platform chemical formed was enhanced by 27% as compared to the batch process. BR was explored as fertilizer substitute aiming to close the loop in the management of CPW towards development of a zero-waste process demonstrating that although the material imposed stress on plant growth, the content of potassium, phosphorus and nitrogen in the mixture increased

Bioprocess development for the production of succinic acid from orange peel waste

A preliminary study has been conducted for the development of a bioprocess targeting the valorization of orange peel waste (OPW). Essential oils and pectin were recovered from OPW through distillation, acid hydrolysis and precipitation with ethanol. Optimal conditions for dilute-acid hydrolysis were investigated via estimation of the sugars released and fermentation. Hydrolysis conditions of 109 o C for 20 min and 116 o C for 10 min using 5 % of dry raw material produced the highest sugar yields at 0.76 and 0.77 (gtotal sugars gdry raw material-1) respectively. In order to test the efficiency of enzyme hydrolysis as a pretreatment method for OPW valorization, cellulase production from T. reesei was investigated, which was maximized following 5 days of cultivation. Furthermore, elemental analysis in hydrolyzates from dilute-acid hydrolysis and a combination of acid and enzyme hydrolysis was performed. The results indicate that during acid/enzyme hydrolysis, high concentrations of Mg2+ and Ca2+ ions are liberated in contrast to dilute-acid hydrolysis. A. succinogenes fermentations of glucose and fructose were performed and the succinic acid yields achieved were 0.66 (gsuccinic acid gglucose-1) and 0.33 (gsuccinic acid gfructose-1) respectively, while galactose was not fermented. Overall, OPW may serve as a promising raw material for simultaneous production of essential oils, pectin and succinic acid