Evaluation of the impact of pre-treatment and extraction conditions on the polyphenolic profile and antioxidant activity of Belgium apple wood

This study describes the possibilities of valorising a waste stream that originates from apple wood by mapping the reducing capacity and phenolic profile from extracts derived from apple tree (Malus domestica). This study evaluated the efficiency of warm solvent extraction (WSE) and ultrasound-assisted extraction (UAE) techniques for extracting antioxidant phenolic compounds from the bark and core wood of an apple tree cultivated in the north-eastern part of Belgium. Furthermore, the influence of the pre-treatment technique, namely, fresh, oven-dried, and freeze-dried samples, respectively, on the yield of polyphenols was studied. Fresh bark extract obtained by UAE—the most efficient extraction technique—employing acetone 60% v/v contains the highest levels of phenolic compounds as well as the highest antioxidant activity. High-performance liquid chromatographic analysis shows that phloridzin is the major compound of the identified polyphenol markers present in bark and core wood extracts. Based on the obtained results, it may be possible to produce a polyphenolic extract from apple wood at an industrial scale without extensive costs or altering the antioxidant properties. This study reveals the potential of apple tree wood residues valorisation through the recovery of phenolic compounds for food, pharmaceutical, and cosmetic applications.Annick Boeykens is a beneficiary of a PWO (‘Projectmatig Wetenschappelijk Onderzoek’) Grant, provided to Odisee by the Flem-ish Government, for the investigation project ‘Phenolic compounds in by-products’. Manuela M. Moreira (SFRH/BPD/97049/2013) wishes to acknowledge Fundo Social Europeu and Ministério da Ciência, Tecnologia e Ensino Superior for funding her postdoctoral fellowship by means of a POPH-QREN—Tipologia 4.1—Formação Avançada. The financial support from FCT/MEC through national funds and cofi-nanced by FEDER, under the Partnership Agreement PT2020 through the project UID/QUI/50006/2013—POCI/01/0145/FEDER/007265 and the project 6818—Transnational Cooperation, Agreement between Por-tugal (FCT) and Serbia (MSTD) are also acknowledged.info:eu-repo/semantics/publishedVersio

Valorization of apple tree wood residues by polyphenols extraction: Comparison between conventional and microwave-assisted extraction

For the first time, the characterization of antioxidant activity and phenolic profile of apple tree (Malus domestica) bark, core and roots was carried out. Phenolic compounds were extracted from the Belgium apple tree wood residues collected at two seasons, namely summer 2015 and winter 2016, using conventional (CE) and microwave-assisted extraction (MAE) techniques. For each extraction technique, the influence of the most important operational parameters, namely solvent composition, extraction time and temperature, on the total phenolic and flavonoid content, and antioxidant activity by the 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity (DPPH-RSA) and ferric reducing activity power (FRAP) assays were optimized. The phenolic profile from the obtained extracts was also characterized by high-performance liquid chromatography with photodiode array detection (HPLC-PDA). Optimum conditions were: 20 mL ethanol:water 60:40 v/v, 20 min, 100 °C, sample weight 0.1 g for MAE and 20 mL ethanol:water 50:50 v/v, 2 h, 55 °C, sample weight 0.5 g for CE. Root extracts obtained by MAE (the most efficient technique) presented the highest phenolic (47.7 ± 0.9 mg gallic acid equivalents/g dry weight) and flavonoid (17.1 ± 0.8 mg epicatechin equivalents/g dry weight) content, and antioxidant activity (28.4 ± 2.0 mg trolox equivalents/g dry weight and 36.1 ± 2.7 mg ascorbic acid equivalents/g dry weight for DPPH-RSA and FRAP assays, respectively), followed by bark and core wood extracts. HPLC-PDA analysis revealed that phloridzin was the main contributor to the phenolic composition representing 52%–87% of the total amount of phenolic compounds quantified, while phenolic acids represents less than 10%. This study reveals the potential of apple tree wood residues valorization through the recovery of phenolic compounds for food, pharmaceutical and cosmetic applications.info:eu-repo/semantics/publishedVersio

All Effects of Psychophysical Variables on Color Attributes: A Classification System

This paper reports the research and structuring of a classification system for the effects of psychophysical variables on the color attributes. A basic role of color science is to psychophysically specify color appearance. An early stage is to specify the effects of the psychophysical variables (as singles, pairs, etc) on the color attributes (as singles, pairs, etc), for example to model color appearance. Current data on effects are often scarce or conflicting. Few effects are well understood, and the practice of naming effects after their discoverer(s) is inadequate and can be confusing. The number and types of possible effects have never been systematically analyzed and categorized. We propose a simple and rigorous system of classification including nomenclature. The total range of effects is computed from the possible combinations of three psychophysical variables (luminance, dominant wavelength, purity) and six color attributes (lightness, brightness, hue, chroma, colorfulness, saturation) in all modes of appearance. Omitting those effects that are normally impossible to perceive at any one time (such as four- or five-dimensional colors), the total number perceivable is 161 types of effects for all modes of appearance. The type of effect is named after the psychophysical stimulus (or stimuli) and the relevant color attribute(s), e.g., Luminance-on-hue effect (traditionally known as Bezold-Brucke effect). Each type of effect may include slightly different effects with infinite variations depending on experimental parameters.M. Melgosa was supported by the Ministry of Economy and Competitiveness of the Government of Spain, research project FIS2013-40661-P, with the European Research Development Fund

Valorization of apple tree wood residues by polyphenols extraction: Comparison between conventional and microwave-assisted extraction

status: publishe

Evaluation of the impact of pre-treatment and extraction conditions on the polyphenolic profile and antioxidant activity of Belgium apple wood

This study describes the possibilities of valorising a waste stream that originates from apple wood by mapping the reducing capacity and phenolic profile from extracts derived from apple tree (Malus domestica). This study evaluated the efficiency of warm solvent extraction (WSE) and ultrasound-assisted extraction (UAE) techniques for extracting antioxidant phenolic compounds from the bark and core wood of an apple tree cultivated in the north-eastern part of Belgium. Furthermore, the influence of the pre-treatment technique, namely, fresh, oven-dried, and freeze-dried samples, respectively, on the yield of polyphenols was studied. Fresh bark extract obtained by UAE—the most efficient extraction technique—employing acetone 60% v/v contains the highest levels of phenolic compounds as well as the highest antioxidant activity. High-performance liquid chromatographic analysis shows that phloridzin is the major compound of the identified polyphenol markers present in bark and core wood extracts. Based on the obtained results, it may be possible to produce a polyphenolic extract from apple wood at an industrial scale without extensive costs or altering the antioxidant properties. This study reveals the potential of apple tree wood residues valorisation through the recovery of phenolic compounds for food, pharmaceutical, and cosmetic applications.status: Published onlin

Towards a new colour appearance model for self-luminous stimuli

Based on the experimental visual data obtained for self-luminous stimuli surrounded by a dark background, a new colour appearance model (CAM) for unrelated self-luminous stimuli, CAM15u, was developed. The model can be a valuable tool to improve existing standards for traffic signs, LED billboards, etc. Furthermore, first experimental results about the assessment of the colour appearance of similar stimuli but surrounded by a luminous background are presented. This is considered as a first step to a general CAM for self-luminous stimuli.status: publishe

Chemical Characterization and In Vitro Bioactivity of Apple Bark Extracts Obtained by Subcritical Water

Recently, the value of wood residues has received increasing attention due to the presence of pharmacologically active compounds. In the present study, apple bark was treated with subcritical water (SWE) with the aim of bioactivity determination and chemical analysis by GC–MS applying two different sample preparation protocols and by HPLC. Extracts were screened for their total antioxidant capacity by means of total phenolic (TPC) and flavonoid contents (TFC), ferric reducing antioxidant power (FRAP) and DPPH-radical scavenging activity (DPPH-RSA). Anti-microbial and anti-proliferative activities of the apple bark subcritical water extracts were also examined. Different lignin and cellulose degradation products were identified by GC–MS, as well as naturally present compounds. Identified compounds encompassed organic and fatty acids, alcohols, sugars, phenol, benzaldehyde, cinnamic acid, cinnamaldehyde and azulene derivatives, as well as other organic compounds. Phenolic profiles of apple bark extracts defined by HPLC–PDA analysis revealed that the main contributors were gallic acid (9.4 ± 0.5 mg/g DW) and catechin (8.3 ± 0.4 mg/g DW). The diversity of the extracts composition supports the fact that this medium is able to extract compounds of different polarities, simultaneously acting as catalyst and reactant. The characterized apple bark extracts demonstrated good antioxidant (TPC = 31.47 ± 1.86 mg GAE/g; TFC = 17.40 ± 1.89 mg EE/g; FRAP = 22.45 ± 2.22 mg AAE/g; DPPH-RSA = 22.57 ± 2.24 mg Trolox E/g DW), antimicrobial (MIC = 19.53–156.25 μg/mL) and anti-proliferative activity (IC50 = 19.88–47.44 μg/mL). The findings of this study showed that SWE can be used as an environmentally friendly and safe technique for the valorization of apple tree wood residues, applicable in food and pharmaceutical industries.The authors are grateful to the Serbian Ministry of Education, Science and Technological Development (451-03-68/2020-14/200134), Provincial Secretariat for High Education and Scientific Research AP Vojvodina, Serbia (Project No. 142-451-3240/2020-03), Provincial Secretariat for Science and Technological Development and Portuguese Ministry of Science (FCT/Servia 2015/2016 proc. 441.00 SERVIA). Financial support from the Ministerio de Economía y Competitividad (Spanish Government) through the Grant CTQ2016-77155-R is also gratefully acknowledged. R. Suárez thanks to the Conselleria d’Educació, Cultura i Universitats from the Government of the Balearic Islands for a PhD stipend co-financed by Fondo Social Europeo (FPI/1444/2012). S. Clavijo acknowledges to Torres Quevedo Program of the Ministerio de Economía y Competitividad (MINECO) co-financed by European Funds, for the financial support through the PTQ 15-08038. This work was also supported by UIDB/50006/2020 and UIDP/50006/2020 by the Fundação para a Ciência e a Tecnologia (FCT)/Ministério da Ciência, Tecnologia e Ensino Superior (MCTES) through national funds. Manuela M. Moreira (project CEECIND/02702/2017) is grateful for the financial support financed by national funds through FCT and to REQUIMTE/LAQV. Manuela M. Moreira (SFRH/BPD/97049/2013) and M. F. Barroso (SFRH/BPD/78845/2011) are grateful for the postdoctoral fellowships financed by POPH-QREN—Tipologia 4.1—Formação Avançada, subsidized by Fundo Social Europeu and Ministério da Ciência, Tecnologia e Ensino Superior. The financial support from Fundação para a Ciência e Tecnologia/ Ministério da Ciência, Tecnologia e Ensino Superior (FCT/MEC) through national funds and co-financed by European Regional Development Fund (FEDER), under the Partnership Agreement PT2020 through the project UID/ QUI/50006/2013—POCI/01/0145/FERDER/007265 is also acknowledged. Annick Boeykens wishes to acknowledge Odisee for funding by means of a PWO grant (Flemish Government; Belgium).info:eu-repo/semantics/publishedVersio