Kinetics of ascorbic acid degradation in fruit-based infant foods during storage

The kinetics of ascorbic acid (AA) degradation in a fruit-based beikost product added with AA were determined after storage at 4, 25, 37 and 50 °C during 4, 8, 12, 16 and 32 weeks in plastic polypropylene/ethylenevinyl alcohol vacuum packaging. It was confirmed that AA degradation followed an Arrhenius first-order kinetics, with an activation energy of 20.11 ± 0.33 kcal mol−1. No AA losses at 4 °C were recorded during the entire storage period. In contrast, a time - and temperature - dependent decrease (p the degradation rate decreasing from 50 °C to 25 °C, as expected. AA percentage retention at the end of storage ranged between 6.4% (50 °C/16 weeks) and 100.9% (4 °C/32 weeks)

Non-thermal processing effects on fruits and vegetables phytonutrients

The health‐promoting effects of many phytonutrients are attributed mainly to their antioxidant activity, although there may be other modes of action. The demand for high quality food with high phytonutrients content is attracting a lot of attention, as it provides health benefits and has been shown to possess antimicrobial, antiviral, antiparasitic, anti‐inflammatory, antioxidant, antimutagenic, and antitumor effects. To maintain food quality at the highest possible levels, there is a need to develop novel processing techniques such as non‐thermal processing. This chapter discusses novel non‐thermal processing techniques, including ultraviolet radiation, high pressure processing (HPP), dense phase carbon dioxide (DPCD), ultrasound processing, and pulsed electric field (PEF). The application of HPP and its effects on quality attributes, specific to the phytochemical compounds in fruits and vegetables. High pressure offers a technology that can achieve the food safety properties of heat‐treated foods while meeting consumer demand for fresher tasting food products

Determination of environmental flows in rivers using an integrated hydrological-hydrodynamic-habitat modelling approach

[EN] We propose the novel integrated modelling procedure 3H-EMC for the determination of the environmental flow in rivers and streams; 3H-EMC combines Hydrological, Hydrodynamic and Habitat modelling with the use of the Environmental Management Classes (EMCs) that are defined by the Global Environmental Flow Calculator. We apply 3H-EMC in the Sperchios River in Central Greece, in which water abstractions for irrigation cause significant environmental impacts. Calculations of the hydrodynamic-habitat model, in which the large and the small chub are the main fish species, suggest discharge values that range from 1.0 m3/s to 4.0 m3/s. However, hydrological modelling indicates that it is practically difficult to achieve discharges that are higher than approximately 1.0-1.5 m3/s. Furthermore, legislation suggests significantly lower values (0.4-0.5 m3/s) that are unacceptable from the ecological point of view. This behaviour shows that a non-integrated approach, which is based only on hydrodynamic-habitat modelling does not necessarily result in realistic environmental flows, and thus an integrated approach is required. We propose the value of 1.0 m3/s as the "optimum" environmental flow for Sperchios River, because (a) it satisfies the habitat requirements, as expressed by the values of weighted useable area that are equal to 2180 and 1964 m2 for the large and small chub, respectively, and correspond to 82 and 95% of their respective maximum values, (b) it is consistent with the requirements of Environmental Classes A and B, whose percentiles are higher than 75% for discharge (77.2%) and for habitat availability (>83.5% for the large chub and >85.0% for the small chub), (c) it is practically achievable from the hydrological point of view, and (d) it is higher than the value proposed by the Greek legislation. The proposed modelling approach can be applied to any river or stream using the same or similar modelling tools, which should be linked via suitable coupling algorithms.Hydraulic field measurements were performed within the framework of a research project by the Hellenic Centre of Marine Research (HCMR) entitled KRIPIS “Development of an integrated management system for river basin, coastal and marine zones” (http://imbriw.hcmr.gr/en/). Fish habitat data were collected within the framework of the ECOFLOW research project (www. ecoflow.gr). A part of the modelling work has been performed, while the first author was a visiting professor at the Technical University of Munich (TUM); thanks are due to the Bavarian State Ministry of Education and Cultural Affairs and the German Academic Exchange Service (DAAD).Stamou, A.; Polydera, A.; Papadonikolaki, G.; Martinez-Capel, F.; Muñoz Mas, R.; Papadaki, C.; Zogaris, S.... (2018). Determination of environmental flows in rivers using an integrated hydrological-hydrodynamic-habitat modelling approach. Journal of Environmental Management. 209:273-285. https://doi.org/10.1016/j.jenvman.2017.12.038S27328520

Development of a Multi-Enzymatic Biocatalytic System through Immobilization on High Quality Few-Layer bio-Graphene

In this work, we report the green production of few-layer bio-Graphene (bG) through liquid exfoliation of graphite in the presence of bovine serum albumin. Microscopic characterization evaluated the quality of the produced nanomaterial, showing the presence of 3–4-layer graphene. Moreover, spectroscopic techniques also confirmed the quality of the resulted bG, as well as the presence of bovine serum albumin on the graphene sheets. Next, for the first time, bG was used as support for the simultaneous covalent co-immobilization of three enzymes, namely β-glucosidase, glucose oxidase, and horseradish peroxidase. The three enzymes were efficiently co-immobilized on bG, demonstrating high immobilization yields and activity recoveries (up to 98.5 and 90%, respectively). Co-immobilization on bG led to an increase of apparent K(M) values and a decrease of apparent V(max) values, while the stability of the nanobiocatalysts prevailed compared to the free forms of the enzymes. Co-immobilized enzymes exhibited high reusability, preserving a significant part of their activity (up to 72%) after four successive catalytic cycles at 30 °C. Finally, the tri-enzymatic nanobiocatalytic system was applied in three-step cascade reactions, involving, as the first step, the hydrolysis of p-Nitrophenyl-β-D-Glucopyranoside and cellobiose

Orange juice processing using a continuous flow ultrasound-assisted supercritical CO2 system: Microbiota inactivation and product quality

[EN] The feasibility of using supercritical CO2 assisted by ultrasound (SC-CO2-HPU) in continuous mode (3.06 min residence time) for the non-thermal pasteurization of orange juice was evaluated. The proposed technology was effective for microbial inactivation; complete inactivation was obtained for E. coli and total aerobic mesophilic bacteria while 99.7% reduction for S. cerevisiae. Results showed that the SC-CO2-HPU treatment brought about small changes in the pH, Brix and titratable acidity of the juice. Furthermore, although SC-CO2-HPU technology produced a higher browning index (211%) and greater changes in color, it was possible to improve the cloud of juice by 173%; what is more, a smaller percentage of phenolic compounds (6.5%) and ascorbic acid (5.5%) was lost compared to the thermally pasteurized juice (10% decrease in both parameters). Moreover, the antioxidant capacity could be increased (12%) with respect to the natural juice. Therefore, SC-CO2-HPU technology appears to be effective for microbial pasteurization and the mild process conditions used could lead to an increase in the juice quality. Industrial relevance: The demand for high quality processed foods which preserve their natural and fresh-like characteristics has awakened a growing interest in non-thermal technologies. The ultrasound-assisted SC-CO2 continuous system is an innovative non-thermal technology that could represent a development in the area of emerging technologies. This technology allows high quality products to be obtained by preserving their natural bioactive compound content while maintaining their fresh-like organoleptic characteristics. In fact, food experts working in academia, industry or governmental agencies worldwide foresee that non-thermal emerging technologies will be among the most impactful novel food processing technologies for the next decade in terms of product commercialization.This work was supported by the PROMETEOII\2014\005 project financed by the Generalitat Valenciana (Conselleria d'Educació, Cultura i Esport, Valencia, Spain). The authors acknowledge the Consejo Nacional de Ciencia y Tecnología (CONACyT) for the scholarship awarded to PhD Student Paniagua-Martínez, I.Paniagua-Martínez, I.; Mulet Pons, A.; García Alvarado, MÁ.; Benedito Fort, JJ. (2018). Orange juice processing using a continuous flow ultrasound-assisted supercritical CO2 system: Microbiota inactivation and product quality. Innovative Food Science & Emerging Technologies. 47:362-370. https://doi.org/10.1016/j.ifset.2018.03.024S3623704

Homogenization pressures applied to citrus juice manufacturing. Functional properties and application

[EN] Homogenization is a unit operation that can be incorporated in citrus juice manufacturing to improve chemical and physical characteristics relevant for use in subsequent processing operations. The aim of this study was to evaluate the effect of different homogenization pressures on suspended solids and antiradical activity in mandarin low pulp juice (LPJ) and to understand their influence on a posterior vacuum impregnation operation. We found the pressure treatments applied to LPJ do not have negative effects on antiradical activity or functional compounds in the juice. In the vacuum impregnation study we found that more LPJ was introduced into the structural matrix of apples when homogenized at higher pressures and therefore more functional compounds may be introduced due to pulp stability and particle size reduction. © 2012 Elsevier Ltd. All rights reservedThe authors acknowledge the Ministerio de Ciencia e Innovacion of Spain for its contribution to projects AGL2009-09905, AGL2009-11805 and PET2008_0015.Betoret Valls, ME.; Sentandreu Vicente, E.; Betoret Valls, N.; Fito Maupoey, P. (2012). Homogenization pressures applied to citrus juice manufacturing. Functional properties and application. Journal of Food Engineering. 111(1):28-33. https://doi.org/10.1016/j.jfoodeng.2012.01.035S2833111

Εφαρμογή νανοσωλήνων άνθρακα για την απορρύπανση υπόγειου νερού και την επεξεργασία υγρών αποβλήτων

Εθνικό Μετσόβιο Πολυτεχνείο--Μεταπτυχιακή Εργασία. Διεπιστημονικό-Διατμηματικό Πρόγραμμα Μεταπτυχιακών Σπουδών (Δ.Π.Μ.Σ.) “Επιστήμη και Τεχνολογία Υδατικών Πόρων