This critical review considers the extensive research and development dedicated, in the last years, to a single polymer, the poly(ethylene 2,5-furandicarboxylate), usually simply referred to as PEF. ...PEF importance stems from the fact that it is based on renewable resources, typically prepared from C6 sugars present in biomass feedstocks, for its resemblance to the high-performance poly(ethylene terephthalate) (PET) and in terms of barrier properties even outperforming PET. For the first time synthesis, properties, and end-life targeting—a more sustainable PEF—are critically reviewed. The emphasis is placed on how synthetic roots to PEF evolved toward the development of greener processes based on ring open polymerization, enzymatic synthesis, or the use of ionic liquids; together with a broader perspective on PEF end-life, highlighting recycling and (bio)degradation solutions.
Lifestyles have changed the eating norm of people leading to chronic and degenerative maladies. In fact, prevailing use of highly processed and convenient-to-eat foods have reduced intake of ...polyphenol rich food importantly fruits and vegetables. Polyphenols are important component of our diet with good antioxidant and high anti-inflammatory properties. Therefore, industries have started to implement particular food processing techniques crucial to achieve food products having high amount of health promoted components with appropriate shelf life. Nowadays, emerging technologies such as high hydrostatic pressure, pulsed electric field, ultrasound, microwave, ohmic heating and irradiation are being studied as an alternative to conventional ones, obtaining promising results. Energy efficiency, environment conservation, processing time reduction and retention of nutritional properties are key benefits for using innovative food processing technologies. The present review will summarize the current knowledge about different novel food processing technologies on the retention of polyphenols.
•Polyphenols in fresh and processed foods are considered helpful against lethal diseases in biological systems.•Conventional methods destroy polyphenols due to intensive processing conditions.•The principle of novel technologies based on minimal processing of raw food leads toward maximum retention of polyphenols.•Overview of emerging technologies have been focused for their advantages and limitations for polyphenols.•Outcomes of the present review recommend the adaptation of novel techniques in food processing industry.
Different position isomers of furandicarboxylic acid (FDCA) can be obtained from the biomass by a Henkel disproportionation reaction. 2,5- and 2,4-FDCA are obtained in amounts that are large enough ...to be used for the synthesis of polyethylene furanoate (PEF). The homopolyesters obtained with ethylene glycol (EG) and either 2,5- or 2,4-FDCA have a completely different crystallization behavior, for 2,5-PEF can crystallize whereas 2,4-PEF cannot, even after very long annealing times. The synthesis of random copolyesters with EG and different ratios of 2,5/2,4-FDCA may therefore allow to tune PEF crystallization ability. The partial replacement of 2,5-FDCA by its position isomer could help disrupting crystallinity analogously to what happens when EG is partially replaced by cyclohexane dimethanol (CHDM) in glycol-modified polyethylene terephthalate (PETg). This work investigates the thermal behavior of the homopolyester 2,5-PEF and the microstructural consequences of copolymerization (replacement of small amounts of 2,5-FDCA with 2,4-FDCA). Crystallization is performed in isothermal conditions after cooling down from the molten state, and investigated with both conventional DSC and Fast Scanning Calorimetry (FSC). When the amount of 2,4-FDCA-based repeating units is low (10 and 15 mol %), crystallization still occurs but with an increased induction time. Neither the crystalline nor the rigid amorphous fractions are significantly affected by copolymerization. Due to multiple and complex microstructural reorganizations observed at relatively slow heating rates, conventional DSC is inaccurate and does not provide a reliable microstructural depiction of these polyesters. The use of FSC is recommended, for it allows to obtain a better characterization of the quality and thermal stability of the formed crystals.
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•The presence of 2,4-FDCA in 2,5-FDCA-based copolyesters tunes their crystallization.•Up to 10–15 mol% 2,4-FDCA, crystallization occurs with an increased induction time.•Neither the crystalline nor the rigid amorphous fractions are significantly affected.•FSC is recommended to characterize the quality and thermal stability of the crystals.•Only small values of XRAF were observed, with little (if any) correlation with XC.
Different parts of a plant (seeds, fruits, flower, leaves, stem, and roots) contain numerous biologically active compounds called “phytoconstituents” that consist of phenolics, minerals, amino acids, ...and vitamins. The conventional techniques applied to extract these phytoconstituents have several drawbacks including poor performance, low yields, more solvent use, long processing time, and thermally degrading by-products. In contrast, modern and advanced extraction nonthermal technologies such as pulsed electric field (PEF) assist in easier and efficient identification, characterization, and analysis of bioactive ingredients. Other advantages of PEF include cost-efficacy, less time, and solvent consumption with improved yields. This review covers the applications of PEF to obtain bioactive components, essential oils, proteins, pectin, and other important materials from various parts of the plant. Numerous studies compiled in the current evaluation concluded PEF as the best solution to extract phytoconstituents used in the food and pharmaceutical industries. PEF-assisted extraction leads to a higher yield, utilizes less solvents and energy, and it saves a lot of time compared to traditional extraction methods. PEF extraction design should be safe and efficient enough to prevent the degradation of phytoconstituents and oils.
Pulsed electric field (PEF) is promising in food industry in modifying properties of materials. The influences of PEF pretreatment on hydrolysis, texture, multi-scale and semi-crystalline lamellar ...structure, thermal properties, and flavor of rice were investigated with two special treatments for high and low contents of slowly digestible starch and resistant starch, using enzymatic hydrolysis, scanning electron microscopy, differential scanning calorimetry, X-ray diffractometry, small angle X-ray scattering, attenuated total-reflection Fourier-transform infrared spectrometry, texture profile analysis, and gas chromatography-mass spectrometry (MS)-MS. Upon PEF pretreatment, the starch hydrolysis degree and glycemic index of cooked rice increased slightly; the hardness, springiness, cohesiveness and chewiness of cooked rice increased significantly (P < 0.05). PEF reduced the integrity of cell structure, altered the gelatinization enthalpy, relative crystallinity degree, semi-crystalline layered structure of rice lightly, without obviously changing the diffractive pattern type of rice grains. PEF pretreatment caused decrease of phenols and ketones and increase of acids and aldehydes in cooked rice.
•Pulsed electric field (PEF) significantly affected texture of cooked rice.•PEF significantly enhanced starch hydrolysis and increased glycemic index of cooked rice.•PEF significantly changed composition of volatile compounds of rice.
Among “green” alternatives for oil-based commodity plastics like Polyethylene, Polyamides, and Poly(Ethylene Terephthalate), a new class of polyesters synthesized from furandicarboxylic acids (FDCAs) ...currently is in the spotlight of both the academic and industrial communities. Of particular interest is Poly(Ethylene-2,5-Furanoate) (PEF), which can be synthesized from monomers derived from sugars and exhibits physical properties that imply large substitution potential for PET in bottle, fiber and packaging applications. In this study the structure-thermal properties relationship of PEF have been investigated in order to explain the complex behavior exhibited by PEF during isothermal crystallization. Secondary crystallization and melt-recrystallization processes have been identified in order to explain the observed behavior. The existence of a critical crystallization temperature around 170 °C marking a transition in terms of crystalline phase induced is also pointed out. Moreover, data such as the molecular weight between entanglements (Me) and standard melting enthalpy (ΔHm°) have been determined. In addition the crystalline morphology was characterized by means of SAXS and WAXS. The influence of the crystallization conditions on this morphology is given. As a main result it has been found that depending on the crystallization temperature (Tc), a disordered or an ordered crystalline phase (called α′ and α respectively) are formed at low (Tc ≤ 170 °C) and high (Tc ≥ 170 °C) temperatures, respectively. Finally, evidence for the formation of a rigid amorphous phase during crystallization is presented, indicating that a three-phase model has to be considered in order to provide an appropriate description of the morphology in semi-crystalline PEF.
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•First evidence of a defective crystalline form in PEF depending on the crystallization temperature.•Explanation of the multiple melting phenomenon.•ΔHm° = 140 J/g.•Mass between entanglements = 3500 g/mol.•Existence of a rigid amorphous phase in PEF.
•PEF treatment increased the biomolecules recovery from Chlorella.•More proteins and polyphenols were obtained using water as solvent.•More chlorophyll a and b, and carotenoids were obtained using ...50% DMSO as solvent.•The extracts concentration of Mg, P, Ca, Fe and Zn were analyzed.•The fluorescence and SEM microscopy revealed the electroporation effect of PEF.
This study investigated the effects of pulsed electric field (PEF) (3 kV/cm, 44 pulses, 99 kJ/kg), solvent (H2O or 50 % DMSO) and time (0, 10, 20, 30, 60, 90, 120 and 180 min) on the extraction of Chlorella antioxidant biomolecules and minerals. The results showed that PEF treatment increased the biomolecules recovery. For the extraction time of 120 min, more proteins and polyphenols were obtained using water, while more chlorophyll a and b, and carotenoids were obtained using 50 % DMSO as the extraction solvent. The extracts mineral concentration (PEF vs control) were analysed including Mg, P, Ca, Fe and Zn, and the Relative Nutrient Values results indicated that Chlorella H2O-extracts could be used as a mineral source for different populations. Finally, the fluorescence and scanning electron microscopy revealed the electroporation effect of PEF.
In this study, the impact of a pulsed electric field (PEF) treatment on the final quality of freeze-dried apples was investigated. The PEF treatment has been performed at an electric field intensity ...equal to 1.07 kV/cm and a specific energy input of 0.5, 1 and 5 kJ/kg. The samples were freeze-dried (without a separate pre-freezing step) at varying temperatures (set on 40 °C and 60 °C) and pressures (0.1, 0.25 and 1 mbar). The quality of dried material was evaluated by the analysis of residual moisture content, macro- and microscopic properties, colour, the total content of phenolic compounds and the antioxidant activity as well as texture and acoustic properties. It was found that the residual moisture content of PEF treated samples was reduced by up to ∼82% in comparison to the intact tissue. For electroporated samples, a good preservation of macro-shape, an inhibition of shrinkage and the development of large pores were observed. The PEF treated material exhibited a higher total phenolic content, but a smaller antioxidant activity. Mechanical and acoustic analysis showed a higher crunchiness and brittleness for PEF-treated tissue, whereas untreated tissue was characterised by a harder and rather crackly texture.
•Application of PEF before freeze-drying preserved the shape of apples.•PEF pre-treated freeze-dried apples exhibited better crunchiness.•Freeze-dried apples subjected to PEF exhibited higher total polyphenol content.
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