Convective air drying of brown seaweed Bifurcaria bifurcata in thin layer configuration

[EN] Air drying kinetics of Bifurcaria bifurcata brown seaweed at 35, 50, 60 and 75°C were determined. Experimental drying data were modelled using two-parameter Page model (n, k). Page parameter n was constant (1.28) at tested temperatures, but k increased significantly with drying temperature from 35 to 60ºC and was invariant at higher temperatures (up to 75ºC). Drying experiments allowed the determination of the critical moisture content of seaweed (1.6 ± 0.2 kg water (kg d.b.)−1). Mass transfer coefficients during constant drying rate period and effective coefficients of water diffusion during falling drying rate period were evaluated, assuming cyclindrical geometry and considering volumetric shrinkage.The authors acknowledge the financial support of the Ministry of Economy and Competitiveness of Spain and European Regional Development Fund (ERDF) of European Union by the research project (CTQ 2013-43616/P).Arufe-Vilas, S.; Sineiro, J.; Chenlo, F.; Moreira, R. (2018). Convective air drying of brown seaweed Bifurcaria bifurcata in thin layer configuration. En IDS 2018. 21st International Drying Symposium Proceedings. Editorial Universitat Politècnica de València. 355-362. https://doi.org/10.4995/IDS2018.2018.7497OCS35536

Effect of air drying temperature on phytochemical properties of brown seaweed Bifurcaria bifurcata

[EN] The purpose of this study was to determine the effects of convective air-drying at different temperatures (35, 50, 60 and 75°C) on the color of Bifurcaria bifurcata (BB) seaweed powders obtained after milling, the antioxidant activity and polyphenolic and carbohydrate content of the aqueous extracts obtained by ultrasound-assisted extraction. BB seaweed powders exhibited significant color differences between powders obtained from BB dried at 35ºC (yellowish-green) and 50–75 °C (brown). High air drying temperature (above 60ºC) significantly reduced the total polyphenolic, carbohydrate content and scavenging activity of aqueous extracts of BB.The authors acknowledge the financial support of the Ministry of Economy and Competitiveness of Spain and European Regional Development Fund (ERDF) of European Union by the research project (CTQ 2013-43616/P).Arufe, S.; Sineiro, J.; Chenlo, F.; Moreira, R. (2018). Effect of air drying temperature on phytochemical properties of brown seaweed Bifurcaria bifurcata. En IDS 2018. 21st International Drying Symposium Proceedings. Editorial Universitat Politècnica de València. 865-872. https://doi.org/10.4995/IDS2018.2018.7496OCS86587

Physicochemical and Structural Properties of Starch Isolated from Fresh and Dried Chestnuts and Chestnut Flour

U radu su određeni sljedeći parametri: raspodjela veličine čestica, boja, morfologija i kemijski sastav škroba dobivenog iz svježih plodova kestena (Castanea sativa Mill.), plodova prosušenih na sobnoj temperaturi, te iz kupovnog kestenovog brašna. Raspodjela je veličina čestica u sve tri vrste škroba bila bimodalna, pa su u škrobu iz svježeg kestena opažene dvije veličine zrnaca, i to mala (promjera od 1,5 μm) i velika zrnca (10,5 μm). Veličina je zrnaca škroba ovisila o udjelu vlage u uzorcima. Najveća su zrnca opažena u škrobu iz svježeg kestena, a najmanja u onom iz kupovnog brašna, međutim, morfološke značajke zrnaca nisu bile bitno različite. Većina je zrnaca imala okrugli ili ovalni oblik, a samo su poneka bila trolisnog oblika, što nije uobičajeno u drugim vrstama škroba. Uzorci su škroba iz kupovnog brašna imali najtamniju, a uzorak iz svježih plodova kestena najsvijetliju boju. Ukupan se udjel škroba u ispitanim uzorcima bitno razlikovao, a izolacija je škroba iz sušenih plodova kestena bila uspješnija. U svim je uzorcima bilo malo oštećenih zrnaca škroba (<2,91 %), a maseni je udjel amiloze bio srednje velik (od 17,0 do 25,8 % na bazi suhe tvari). Najmanji je udjel amiloze pronađen u škrobu iz svježih plodova kestena, iako još uvijek unutar vrijednosti ostalih uobičajenih vrsta škrobova.Particle size distribution, colour, morphology and chemical composition of chestnut (Castanea sativa Mill.) starches isolated from fresh chestnut fruits (S1), semi-dried chestnut fruits at room temperature (S2) and commercial chestnut flour (S3) were determined using several experimental techniques. All starches had a bimodal particle size distribution, particularly S1 showed two types of starch granules – small (1.5 μm diameter) and large granules (10.5 μm). Starch granule sizes depended on the moisture content of the samples, decreasing slightly in the following order S1>S2>S3; however, no significant differences were observed in the morphological analysis. Most of the granules exhibited round or oval shapes, and exceptionally, some of them featured trefoil shape, which is not usually found in other starches. Colour results indicated that S3 samples had the darkest colour, followed by S2 and S1. Tested chestnut starches showed significant differences in total starch content, with starch isolation being more selective in dried samples. All samples showed low damaged starch (<2.91 %) and intermediate amylose (from 17.0 to 25.8 %) content on dry mass basis. The lowest amount of amylose was obtained in S1, even though it was within the range of common commercial starches

Osmotic dehydration of chestnut using static and dynamic media of salt, sucrose and glucose

Se estudió la deshidratación osmótica de la castaña en disoluciones acuosas de sal (17, 22, 26,5 % p/p), sacarosa (40, 50, 60 % p/p) y glucosa (40, 50, 56,5 % p/p) a diferentes grados de agitación (0, 40, 110 rpm) y tiempos (1, 2, 4, 8 h) a 20 ºC. En las disoluciones de glucosa se estudió el efecto de la temperatura (50 ºC). Se determinaron los parámetros cinéticos de ganancia de sólidos, pérdida de agua, reducción de peso y relación pérdida de agua-ganancia de sólidos. Al aumentar la agitación, aumentó la ganancia de sólidos, la pérdida de agua y disminuyó la relación entre ambos, especialmente cuando las disoluciones tuvieron elevada viscosidad. Las cinéticas de los contenidos de humedad y de sólidos se modelizaron mediante la ecuación de Hawkes y Flink para tiempos cortos. Se determinaron los coeficientes de transferencia para el agua y el soluto osmótico y los coeficientes de difusividad mediante la ley de Fick.Chestnut fruits were submitted to osmotic dehydration in sodium chloride (17, 22, 26.5 % w/w), sucrose (40, 50, 60 % w/w) and glucose (40, 50, 56.5 % w/w) solutions at different stirring rates (0, 40, 110 rpm) and periods of time (1, 2, 4, 8 h) at 20 ºC. The effect of temperature (50 ºC) was studied in the case of samples dehydrated with glucose solutions. Several parameters for each dehydration process such as solids gain, water loss, and its corresponding ratio and weight reduction, were determined. High stirring rates increased solids gain and decreased water loss and its ratio, especially in the case of solutions of high viscosity. Moisture and solids gain contents were modelled by Hawkes and Flink equation for short times and water and osmotic solute transfer coefficients were calculated. The corresponding effective coefficients of diffusion were also evaluated by means of Fick’s law.Los autores agradecen a la Xunta de Galicia (España) y a FEDER el apoyo parcial con el proyecto PGIDIT04TAL265004PRS

Revista galega do ensino

Se explica el perfil profesional y el plan de estudios de un Ingeniero Químico de la Universidad de Santiago de Compostela. Comprende 336 créditos repartidos en 2 ciclos de 3 y 2 años. Las materias impartidas tienen carácter troncal, optativo y obligatorio, siendo las del segundo ciclo más específicas. Al terminar los estudios se ha de realizar un proyecto fin de carrera.GaliciaBiblioteca de Educación del Ministerio de Educación, Cultura y Deporte; Calle San Agustín, 5 - 3 Planta; 28014 Madrid; Tel. +34917748000; [email protected]

Viscoelastic and Textural Characteristics of Gels Obtained from Potato Starch Roasted under Several Temperature-Time Conditions

The influence of roasting conditions on the potato starch (PS) composition, solubility, crystallinity, gel-forming thermal profiles, and texture of the corresponding gels was studied. Thermorheological testing of roasted starches with (RPS) and without (RPSI) the soluble fraction was conducted on a stress-controlled rheometer. Texture profile analysis (TPA) was used to determine the RPS final gel texture. Solubility tests showed equivalent effects of starch roasting for samples treated at 190°C for 8 h (RPS190-8), 210°C for 6 h (RPS210-6), and 230°C for 4 h (RPS230-4). The apparent amylose content of RPS linearly increased with the decreasing degree of crystallinity. Elastic (G′) and viscous (G″) properties of RPS depended markedly on apparent amylose content and crystallinity. G′gel values of roasted starches linearly increased with the amylose content suggesting a promotion of the amylose breakdown with roasting temperature. Gels prepared with RPS roasted between 120 and 170°C exhibited intermediate strength and fully thermal reversible features. Roasting between 190 and 210°C favoured strong and fully thermal reversible gels. Although RPS230-4 gels exhibited similar strength to RPS190-8 and RPS210-4, no fully thermal reversible gels were obtained. The soluble fraction removal led to a drop the RPSI gels strength with increasing roasting temperature. No water syneresis was identified for RPS gels during one-week ageing, except for RPS230 gels. Relationships between textural parameters from TPA and viscoelastic gel properties determined by rheology were established