<?xml version="1.0" encoding="UTF-8"?><?xml-stylesheet type="text/xsl" href="static/style.xsl"?><OAI-PMH xmlns="http://www.openarchives.org/OAI/2.0/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/ http://www.openarchives.org/OAI/2.0/OAI-PMH.xsd"><responseDate>2026-05-02T08:28:46Z</responseDate><request verb="GetRecord" identifier="oai:riubu.ubu.es:10259/9132" metadataPrefix="xoai">https://riubu.ubu.es/oai/request</request><GetRecord><record><header><identifier>oai:riubu.ubu.es:10259/9132</identifier><datestamp>2024-07-18T10:01:45Z</datestamp><setSpec>com_10259_9433</setSpec><setSpec>com_10259_5087</setSpec><setSpec>com_10259_2728</setSpec><setSpec>col_10259_9434</setSpec></header><metadata><metadata xmlns="http://www.lyncode.com/xoai" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.lyncode.com/xoai http://www.lyncode.com/xsd/xoai.xsd">
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<field name="value">Ruiz Pérez, María Olga</field>
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<field name="confidence">600</field>
<field name="orcid_id">0000-0003-0399-092X</field>
<field name="value">Benito Román, Oscar</field>
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<field name="confidence">600</field>
<field name="orcid_id">0000-0002-4418-0045</field>
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<field name="value">Hernández Manchado, Javier</field>
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<field name="value">Universidad de Burgos. Departamento de Química</field>
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<field name="value">2024-05-06T12:15:05Z</field>
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<field name="value">2024-05-06T12:15:05Z</field>
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<element name="submitted">
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<field name="value">2023-06</field>
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<field name="value">In this work the purification by ultrafiltration using tubular ceramic membranes of pectic&#xd;
oligosaccharides (POS) extracted from onion skin wastes (OSW) was studied.&#xd;
In the first stage of the work, subcritical water was used to promote the hydrolysis of OSW and&#xd;
obtain a liquid hydrolysate rich in POS. For this purpose, three different combinations of&#xd;
temperature and extraction time (115 ºC – 180 min; 125 ºC – 150 min and 135 ºC – 90 min)&#xd;
were used in a batch extractor at 25 bar. In order to consider the combined effect of the&#xd;
temperature and the extraction time, the severity factor (log Ro) was calculated, resulting to be&#xd;
in the range 2.88 to 3.29. The best results in terms of POS concentration (5643 ± 84 mg/L) in&#xd;
the hydrolysate was obtained in the experiment carried out at 125 ºC (log Ro = 3.16). It was&#xd;
also possible to demonstrate that the composition of the liquid hydrolysate was strongly&#xd;
influenced by the extraction conditions: the higher the severity factor the higher the&#xd;
concentration of impurities (organic acids, HMF and furfural) and higher the POS hydrolysis&#xd;
rate. This was demonstrated by the increased concentration of free monosaccharides&#xd;
(glucose, xylose, galactose and arabinose) and the decrease in the POS molecular weight.&#xd;
In the second stage of the work, the aim was to study the separation of POS from the impurities&#xd;
formed during the subcritical water hydrolysis stage, using an ultrafiltration process in&#xd;
diafiltration mode. For this purpose, a 50 kDa tubular membrane was firstly used (Tami&#xd;
Industries, active layer of TiO2 and 132 cm2 of effective area). The fouling mechanism,&#xd;
hydraulic resistance and the purification extent were studied. Important differences in the&#xd;
permeate flux (J) were observed as a function of the subcritical water hydrolysate composition.&#xd;
The permeate flux obtained when filtering the 115 ºC hydrolysate decreased dramatically at&#xd;
the beginning of the experiment to achieve a constant value, whereas the hydrolysates&#xd;
obtained at 125 and 135 ºC exhibited a different behaviour: an initial fast decline of the&#xd;
permeate flux followed by a slower continuous decrease. This result for 125 and 135 ºC&#xd;
hydrolysates can be justified due to the effects of the membrane fouling (fouling mechanism&#xd;
was cake layer formation, according to Hermia’s model). Using this 50 kDa membrane, the&#xd;
POS recovery was 76 % (115 ºC hydrolysate), 58 % for the 125 ºC hydrolysate and 56% for&#xd;
the 135 ºC hydrolysate. In all the cases, a complete removal of the impurities was achieved&#xd;
after the dilution factor of 3.5.&#xd;
To complete the purification experiments, the effect of the removal of the colloidal matter (by&#xd;
centrifugation) present in the 125 ºC hydrolysate was studied using two different membranes&#xd;
(50 and 5 kDa). In the hydrolysate, it was observed the formation of a black precipitate that&#xd;
was responsible for the membrane fouling, hindering the filtration process. The removal of this&#xd;
colloidal matter, which did not affect the POS fraction, was responsible for the reduction of the&#xd;
colour of the hydrolysate by 60 % and the promotion of the filtration process (a faster removal&#xd;
of the impurities was achieved) without loss of the POS fraction. Finally, when a 5 kDa&#xd;
membrane was used, the retention of the POS fraction was higher than 80 % in comparison&#xd;
to the 60 % obtained for the 50 kDa membrane.</field>
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<element name="sponsorship">
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<field name="value">El trabajo presentado ha sido desarrollado en el seno del Grupo de Investigación Biotecnología Industrial y Medioambiental, reconocido por la UBU (GIR-UBU BIOIND) y por la Junta de Castilla y León como Unidad de Investigación Consolidada UIC-128, en el marco de los siguientes proyectos de investigación:&#xd;
PID2020-116716RJ-I00 - Tecnologías de fluidos presurizados para la valorización de subproductos de la industria agroalimentaria: recuperación de pectina y otros compuestos bioactivos de alto valor, financiado por la Agencia Estatal de Investigación.&#xd;
PDC2022-133443-I00 – Diseño de un prototipo para la extracción de bioproductos con agua subcrítica, financiado por el Ministerio de Ciencia e Innovación.&#xd;
TED2021-129311B-I00 - Tecnologías verdes basadas en el empleo de fluidos presurizados para valorizar biomasa lignocelulósica mediante la producción de furfural, financiado por el Ministerio de Ciencia e Innovación.&#xd;
BU050P20 - Valorización de la fracción proteica de subproductos de la industria agroalimentaria de Castilla y León mediante tecnologías de fluidos presurizados, financiado por la Junta de Castilla y León y el Fondo Europeo de Desarrollo Regional (FEDER).</field>
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<field name="value">Este documento está sujeto a una licencia de uso Creative Commons, por la cual está permitido hacer copia, distribuir y comunicar públicamente la obra siempre que se cite al autor original y no se haga de él uso comercial ni obra derivada</field>
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<element name="subject">
<element name="en">
<field name="value">Subcritical water</field>
<field name="value">Oligosaccharide fractionation</field>
<field name="value">Ultrafiltration</field>
<field name="value">Diafiltration</field>
<field name="value">Onion skin waste</field>
<field name="value">Biorefinery</field>
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<field name="value">Ingeniería química</field>
<field name="value">Alimentos</field>
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<field name="value">Chemical engineering</field>
<field name="value">Food</field>
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<element name="title">
<element name="es">
<field name="value">Extracción con agua subcrítica y ultrafiltración para la obtención de pecto-oligosacáridos a partir de residuos de piel cebolla</field>
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