Percorrer por autor "Encina-Zelada, Christian"
A mostrar 1 - 10 de 13
Resultados por página
Opções de ordenação
- Caracterização química e nutricional de grãos de Chenopodium quinoa Willd (quinoa): uma boa alternativa para produtos alimentares nutritivosPublication . Pereira, Eliana; Encina-Zelada, Christian; Barros, Lillian; Gonzales-Barron, Ursula; Cadavez, Vasco; Ferreira, Isabel C.F.R.O interesse da sociedade moderna pela prática de estüos de vida mais saudáveis tem vindo a aumentar gradualmente, nomeadamente no que concerne à mudança dos hábitos alimentares. Assün, tem sido evidente a preferência por alimentos que proporcionam benefícios para a saúde e bem-estar, além de saüsfação nutricional [l]. Desta forma, as sementes de Chenopodium quinoa WÜd (quinoa) têm mostrado possuir um elevado valor nutricional, substitumdo os cereais comummente consumidos e apreciados [2]. Esta espécie, ao longo de vários séculos, foi cultivada nos países andinos como o Peru e a Bolívia, no entanto, hoje em dia, o seu cultivo estendeu-se a outros países, como Austrália, Canadá, China, Inglaterra, Índia, Itália, Paquistão, Estados Unidos, entre outros [3]. O objetivo deste estudo consistiu numa caracterização química e nutricional de 39 amostras pertencentes às variedades mais comuns de C. quinoa (venneUia, preta e branca), provenientes de diferentes origens (comerciais e não comerciais origmárias do Peru e da Espanha). Para tal, o perfil nutricional foi avaliado usando metodologias oficiais de análise de alimentos, os ácidos orgânicos através de um sistema UFLC-PDA, os açúcares livres por HPLC-RI, os tocoferóis por HPLC-fluorescência e os ácidos gordos por GC-FID. Os resultados obtidos revelaram a presença de muitos compostos de interesse, tornando-se primordiais na promoção do consumo deste pseudocereal. O perfil nutricional evidenciou a predominância do teor em hidratos de carbono e proteínas, comparativamente com os restantes macronutrientes analisados. Por outro lado, na determinação dos compostos hidrofílicos foram identificados vários ácidos orgânicos, sendo os ácidos oxálico e cítrico os maioritários. Nos açúcares, verificouse a presença de arabinose, frutose, glucose e sacarose, destacando-se este último como maioritário. Relativamente aos compostos lipofílicos, foi analisado o teor em tocoferóis, identificando-se as isoformas a-, -y- e ô-tocoferol, e o perfil em ácidos gordos, predominando os ácidos gordos insaturados, particularmente os ácidos oleico e linoleico. Tendo em conta as diferentes variedades analisadas (preta, branca e vermelha), não se verificaram alterações estatisticamente significativas na maioria dos parâmetros avaliados. Assim, foi demonstrado que as sementes de quinoa são, claramente, lima excelente escolha para a dieta dos consumidores, exibindo compostos nutritivos mas também moléculas de elevado interesse, como tocoferóis e alguns ácidos orgânicos que promovem benefícios bioativos para o organismo. Deste modo, este pseudocereal assume uma posição de excelência, comparada a outros cereais consumidos com maior frequência, representando um ingrediente promissor para muitos usos na indústria de alimentos.
- Chemical and nutritional characterization of Chenopodium quinoa Willd (quinoa) grains: a good alternative to nutritious foodPublication . Pereira, Eliana; Encina-Zelada, Christian; Barros, Lillian; Gonzales-Barron, Ursula; Cadavez, Vasco; Ferreira, Isabel C.F.R.With the purpose of valuing the species Chenopodium quinoa Willd (quinoa), as well as encouraging the consumption of its grains, this study aimed at providing a detailed evaluation of the nutritional value and chemical composition of several quinoa grains of different colour varieties (black, red and white) from different origins. The results demonstrated an excellent composition, namely in the presence of many compounds of interest, such as organic acids, tocopherols and unsaturated fatty acids, as well as a very favourable nutritional profile, with carbohydrates and proteins being the prominent macronutrients. Regarding the different varieties, statistical analysis showed that there were no significant differences in studied parameters, with the exception of proteins, carbohydrates, oxalic acid, γ-tocopherol and total tocopherols content. Thus, this pseudocereal takes a position of nutritional excellence, compared to others cereals more commonly consumed, thereby representing a promising ingredient for many uses in the food industry.
- Chenopodium quinoa Willd. (quinoa) grains: a good source of phenolic compoundsPublication . Pereira, Eliana; Cadavez, Vasco; Barros, Lillian; Encina-Zelada, Christian; Stojković, Dejan; Soković, Marina; Calhelha, Ricardo C.; Gonzales-Barron, Ursula; Ferreira, Isabel C.F.R.The ingestion of bioactive compounds has revealed health benefits, namely in the prevention and/or treatment of several diseases. This work aims to characterize the phenolic profile of three colour varieties of Chenopodium quinoa Willd. grains (black, red and white), and also evaluate their cytotoxic and antimicrobial activity. All varieties revealed the presence of phenolic compounds, namely, quercetin and kaempferol derivatives. In this study, quinoa grains did not reveal any anti-proliferative capacity in tumour cell lines, and, as expected, they were devoid of any toxicity. All of the analysed extracts possessed antibacterial and antifungal activities (inhibitory and bactericidal/fungicidal) against the microbial strains considered, exhibiting promising values of minimum bactericidal concentrations (mean MBC 0.153–0.916 mg/mL) and minimum fungicidal concentrations (mean MFC 0.211–0.884 mg/mL). Quinoa varieties represent a good source of bioactive compounds, interfering beneficially in the organism, specifically as antimicrobial agents. Thus, these extracts could be used in the development of bioactive ingredients.
- Combined effect of xanthan gum and water content on physicochemical and textural properties of gluten-free batter and breadPublication . Encina-Zelada, Christian; Cadavez, Vasco; Monteiro, Fernando C.; Teixeira, José; Gonzales-Barron, UrsulaThe objective of this study was to evaluate the combined effect of xanthan gum (XG) on physicochemical, rheological and textural properties of gluten-free batter and bread. To prepare gluten-free batter, different levels of XG (1.5, 2.5 and 3.5%) and water (90, 100 and 110%) were added to a base formula of rice (50%), maize (30%) and quinoa flours (20%); and the batters were evaluated in a factorial design. Several properties on both batter (stickiness and back extrusion) and its corresponding bread (loaf specific volume, baking loss, water activity and pH, texture profile, mean cell area, mean cell density, cell size uniformity, void fraction, mean cell compactness and mean cell aspect ratio) were then evaluated. Higher XG doses (p < .001) tended to produce batters of lower stickiness, adhesion and cohesive-strength, yet, of higher firmness, consistency, cohesiveness and viscosity index. After baking, these loaves presented lower specific volume; lower crumb aw, pH, hardness, springiness, mean cell area and void fraction; and higher (p < .001) chewiness, resilience, mean cell density, cell size uniformity and mean cell compactness. The sticker and less consistent batters produced with higher WC rendered larger bread loaves of softer and more springy/resilient crumbs with greater mean cell size and void fraction. Gluten-free loaves of good appearance in terms of higher specific volume, lower crumb hardness, higher crumb springiness, and open grain visual texture were obtained in formulations with 110% WC and XG doses between 1.5 and 2.5%.
- Efeito da goma xantana nos parâmetros de qualidade da massa e do pão sem glútenPublication . Encina-Zelada, Christian; Cadavez, Vasco; Teixeira, José; Gonzales-Barron, UrsulaEste trabalho teve como objetivo estudar o efeito da goma xantana (GX) e da quantidade de água (QA) nas propriedades físico-químicas, reológicas da massa e do pão sem glúten formulado com farinha de quinoa. Os pães foram elaborados com os seguintes ingredientes: farinhas de arroz (50%), de milho (30%) e de quinoa (20%), 6% de óleo vegetal, 3% de açucar, 1,5% de sal e 3% de levedura seca. Foram estudados 3 níveis de GX (1,5, 2,5 e 3,5%) e três níveis de QA (90, 100 e 110%) num plano factorial completo de dois fatores com três níveis e quatro repetições. Foram realizadas análises físico-químicas e reológicas na massa e no pão. Os dados foram analisados por análise de variância utilizando o software R. O volume específico dos pães diminuiu (p<0,0001) com o aumento do teor em GX e aumentou (p<0,0001) com o aumento do QA. As perdas por cozedura variaram entre 11,9 e 14,5%, tendo diminuído (p <0,0001) com o aumento do teor de GX e aumentado (p<0,0001) com o aumento do TA. O aumento do teor de GX diminuiu (p<0,0001) o pH do pão e o aumento do QA conduziu a um aumento (p<0,0001) do pH. As massas produzidas com maior QA apresentaram maior (p<0,0001) pegajosidade (34,7, 36,8 e 44,7 g para 90, 100 e 110% de QA, respetivamente).
- Effect of xanthan gum on physicochemical and textural properties of gluten-free batter and breadPublication . Encina-Zelada, Christian; Teixeira, José; Monteiro, Fernando C.; Gonzales-Barron, Ursula; Cadavez, VascoThe objective of this study was to evaluate the effect of xanthan gum (XG) on physicochemical, rheological and textural properties of gluten-free batter and bread. Batches of gluten-free bread used a base formulation of rice, corn and quinoa flour, and different levels of XG (1.5, 2.5 and 3.5%) and water content (WC; 90, 100 and 110%) in a full factorial design. Although in interaction with water, higher XG doses tended to produce batters of lower stickiness, work of adhesion, strength-cohesiveness; which, when baked, produced loaves of lower specific volume and baking loss; and bread crumb of lower Aw, pH, hardness, springiness, firmness, mean cell area, void fraction, mean cell aspect ratio, and higher firmness, consistency, cohesiveness, adhesiveness, chewiness, resilience, cell density, cell size uniformity and mean cell compactness (p<.OOl). Gluten-free loaves of good appearance in terms of high specific volume, low crumb hardness, high crumb springiness, and open grain visual texture were obtained in formulations with 110% WC and XG doses between 1.5- 2.5%.
- Estimation of composition of quinoa (Chenopodium quinoa Willd.) grains by Near-Infrared Transmission spectroscopyPublication . Encina-Zelada, Christian; Cadavez, Vasco; Pereda, Jorge; Gómez-Pando, Luz; Salvá-Ruíz, Bettit; Teixeira, José; Ibañez, Martha; Liland, Kristian H.; Gonzales-Barron, UrsulaThe aim of this study was to develop robust chemometric models for the routine determination of dietary constituents of quinoa (Chenopodium quinoa Willd.) using Near-Infrared Transmission (NIT) spectroscopy. Spectra of quinoa grains of 77 cultivars were acquired while dietary constituents were determined by reference methods. Spectra were subjected to multiplicative scatter correction (MSC) or extended multiplicative signal correction (EMSC), and were (or not) treated by Savitzky-Golay (SG) filters. Latent variables were extracted by partial least squares regression (PLSR) or canonical powered partial least squares (CPPLS) algorithms, and the accuracy and predictability of all modelling strategies were compared. Smoothing the spectra improved the accuracy of the models for fat (root mean square error of cross-validation, RMSECV: 0.319–0.327%), ashes (RMSECV: 0.224–0.230%), and particularly for protein (RMSECV: 0.518–0.564%) and carbohydrates (RMSECV: 0.542–0.559%), while enhancing the prediction performance, particularly, for fat (root mean square error of prediction, RMSEP: 0.248–0.335%) and ashes (RMSEP: 0.137–0.191%). Although the highest predictability was achieved for ashes (SG-filtered EMSC/PLSR: bootstrapped 90% confidence interval for RMSEP: [0.376–0.512]) and carbohydrates (SG-filtered MSC/CPPLS: 90% CI RMSEP: [0.651–0.901] ), precision was acceptable for protein (SG-filtered MSC/CPPLS: 90% CI RMSEP: [0.650–0.852]), fat (SG-filtered EMSC/CPPLS: 90% CI RMSEP: [0.478–0.654] ) and moisture (non-filtered EMSC/PLSR: 90% CI RMSEP: [0.658–0.833]).
- Estimation of proximate composition of quinoa (Chenopodium quinoa Willd.) flour by near-infrared transmission spectroscopyPublication . Encina-Zelada, Christian; Cadavez, Vasco; Pereda, Jorge; Gómez-Pando, Luz; Salvá-Ruíz, Bettit; Ibañez, Martha; Teixeira, José; Gonzales-Barron, UrsulaThe aim of this study was to develop chemometric models for protein, fat, ashes and carbohydrates contents of quinoa flour using Near-Infrared Transmission (NIT) spectroscopy. Spectra of quinoa flour obtained from grains of 70 different cultivars were scanned while dietary constituents were determined by reference AOAC methods. As a pre-treatment, spectra were subjected to extended multiplicative signal correction (EMSC) with polynomial degree 0, 1 or 2. Next, the Canonical Powered Partial Least Squares (CPPLS) algorithm was applied, and models were compared in terms of accuracy and predictability. For all models, root mean square errors of cross-validation (RMSECV), root meat square errors of prediction (RMSEP) and coefficient of correlation of cross-validation (RCV) were computed. Robust models were obtained when quinoa spectra were pre-processed using EMSC of polynomial degree 2 for both fat (RMSECV: 0.268% and RMSEP: 0.256%) and carbohydrates (RMSECV: 0.641% and RMSEP: 0.643%) following extraction of five CPPLS latent variables. Good coefficients of correlation of prediction (RP: 0.690–0.821) were found for all constituents when models were validated on a test data set consisting of 13 quinoa flour spectra. Thus, good predictions of the dietary constituents of quinoa flour could be achieved by using NIT technology, as implied by the low coefficient of variation of prediction (CVP): 5.64% for protein, 3.88% for fat 7.32% for ashes and 0.80% for carbohydrates contents.
- Estimation of proximate composition of quinoa (Chenopodium quinoa Willd.) flour by near-infrared transmission spectroscopy modelsPublication . Encina-Zelada, Christian; Cadavez, Vasco; Pereda, Jorge; Gómez-Pando, Luz; Salvá-Ruíz, Bettit; Teixeira, José; Ibañez, Martha; Liland, Kristian H.; Gonzales-Barron, UrsulaThe aim of this study was to develop chemometric models for protein, fat, moisture, ashes and carbohydrates contents of quinoa flour using Near-Infrared Transmission (NIT) spectroscopy. Spectra of quinoa flour originated from grains of 77 different cultivars were scanned while dietary constituents were determined in duplicate by reference AOAC methods. As a pre-treatment, spectra were subjected to extended multiplicative signal correction (EMSC) with polynomial degree 0, 1 or 2. The performance of two algorithms, partial least squares regression (PLSR) and Canonical Powered Partial Least Squares (CPPLS), was compared in terms ofaccuracy and predictability. For all dietary constituents,as opposed to PLSR, the CPPLS regression produced lower root meat square errors of cross-validation (RMSECV), lower root meat square errors of prediction (RMSEP) and higher coefficient of correlation of cross-validation (RCV) while retaining fewer number of components. More robust models were obtained when quinoa flour spectra were pre-processed using EMSC of polynomial degree 2 for moisture (RMSECV: 0.564 and RMSEP: 0.648), fat (RMSECV: 0.268 and RMSEP: 0.256) and carbohydrates (RMSECV: 0.641 and RMSEP: 0.643) following extraction of five CPPLS latent variables. High coefficients of correlation of prediction (RP: 0.7-0.8) were found when models were validated on a test data set consisting of 15 quinoa flour spectra. Thus, good predictions of the dietary constituents of quinoa flour could be achieved by using NIT technology, as implied by the low coefficient of variation of prediction (CVP): 6.1% for moisture, 5.6% for protein, 3.9% for fat 7.4% for ashes and 0.8% for carbohydrates contents.
- Optimization of quality properties of gluten-free bread by a mixture design of xanthan, guar, and hydroxypropyl methyl cellulose gumsPublication . Encina-Zelada, Christian; Cadavez, Vasco; Teixeira, José; Gonzales-Barron, UrsulaThe objective of this study was to investigate, by means of a D-optimal mixture design, the combined e ects of hydroxypropyl methyl cellulose (HPMC), xanthan (XG), and guar (GG) gums on physicochemical, rheological, and textural properties of gluten-free batter and bread. For each of the quality properties measured, a two-factor interaction model was fitted, and the significance of its terms was assessed by analysis of variance. Sticky batters were produced with a combination of high dose of GG (0.60%), high-intermediate dose of HPMC (3.36%), and low dose of XG (0.04%). Combinations of high XG dose (0.60%) and intermediate doses of HPMC (3.08%) and GG (0.32%) rendered GF breads of greater specific volume, while lower bread crust luminosity was obtained with combinations of high GG dose (0.60%), low XG dose (0.04%), and high-intermediate HPMC dose (3.36%). Combinations of high-intermediate HPMC dose (3.36%), high GG dose (0.60%), and low XG dose (0.04%) produced both softer crumbs and bread slices of more open visual texture. By using a desirability function that maximized specific volume while minimizing crust luminosity, crumb hardness, and mean cell density, the optimization of hydrocolloids mixture rendered a value of 0.54, for a combination of 0.24% XG, 0.60% GG, and 3.16% HPMC.