Extração de β-glucanas de cevada e caracterização parcial do amido residual Extraction of barley β-glucans and partial characterization of residual starch
2011
Valéria Maria Limberger | Alícia de Francisco | Marivone Rosa Borges | Tatiana Oro | Paulo Jose Ogliari | Patrícia Matos Scheuer | Carolina Montanheiro Noronha
O objetivo do trabalho foi avaliar os parâmetros da extração de β-glucanas de cevada e caracterizar parcialmente o amido residual da extração. Foi desenvolvida metodologia para extração de β-glucanas de cevada sem degradação do amido, avaliando as variáveis pH e temperatura de extração. O percentual de β-glucanas extraída variou de 44,21 a 53,38%, sendo influenciado pela temperatura, e o de amido extraído variou de 65,98% a 77,54%, sendo influenciado pelo pH. O amido residual da extração de β-glucanas de cevada apresentou poder de inchamento e solubilidade de 8,54±0,29% e 6,04±0,073%, respectivamente. O amilograma de ARV desse amido apresentou viscosidade máxima de 164,67±1,30 RVU e quebra de viscosidade de 45,79±2,06 RVU. O espectro de infravermelho do amido residual é típico de amido de cevada nativo e semelhante ao de amidos isolados de milho, trigo e mandioca. De acordo com as micrografias eletrônicas de varredura da fração amido, foi possível visualizar uma mistura de grânulos grandes e lenticulares, com um diâmetro médio de 19,15µm e de granulos pequenos com forma esférica, de 4,78µm. As características demonstradas pelo amido residual da extração de β-glucanas de cevada sugerem sua viabilidade para utilização na indústria de alimentos.<br>The objective of the study was to evaluate the parameters of the extraction of barley´s β-glucans and partially characterize the residual starch after extraction. A method was developed for the extraction of barley β-glucans without damaging the residual starch, assessing the variables pH and extraction temperature. The percentage of β-glucans in the extracted fraction varied from 44,21 to 53,38% , being influenced by temperature and the extracted starch varied from 65,98% a 77,54%, being influenced by pH. The residual starch from barley's β-glucan extraction had a swelling power and solubility of 8.54±0.29% and 6.04±0.07%, respectively. The RVA´s amylograph for this starch showed a maximum viscosity of 164.67±1.30 RVU and breakdown viscosity of 45.79±2.06 RVU. The infrared spectrum of the residual starch was typical of native barley starch and similar to isolated starch from corn, wheat and cassava. According to the scanning electron micrographs fraction of starch, it was possible to see a mixture of large lenticular granules with an average diameter of 19.15µm and small spherically shaped ones, with 4.78µm. The characteristics showed by the residual starch from barley´s β-glucan extraction, suggest a possible application in the food industry.
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