Amidos de sorgos pigmentados com potencial para aplicação na indústria de alimentos
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2022-12-07
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Universidade Federal de Goiás
Resumo
Sorghum (Sorghum bicolor [L.] Moench) is the fifth most-produced cereal in the world, but it
is not homogeneously present in human food worldwide. Like the other species of the Poaceae
family, sorghum is rich in nutrients, mainly starch. Because it has several varieties, sorghum
has different colors and is rich in natural pigments, mainly phenolic acids and antioxidant
compounds. Starch extracted from colored sorghum is a naturally pigmented product and is
generally ignored by the industry as it does not meet the white-bright standard. Therefore, this
work aims to extract and characterize starches from different cultivars of pigmented sorghum
and evaluate their potential for use in the food industry. Initially, a bibliographic review was
carried out about starches extracted from colored raw materials, aiming to understand and
identify their characteristics and properties. Afterward, the aqueous extraction and
characterization of the starch of three colored sorghum cultivars (Comercial Vermelho,
SSG150T, and BRS Ponta Negra) were carried out. Aqueous extraction of the starches was
carried out, whose yields varied between 4 and 6%. Starches were separated into types A and
B for red commercial sorghum and BRS Ponta Negra sorghum. Sorghum SSG150T had only
one type of starch. In total, five different starches from 3 sorghum varieties were analyzed. The
starches were characterized according to their proximal composition, indicating moisture
between 8.32 and 10.84%, ash content close to zero, and water activity between 0.31 and 0.48.
As for the color analysis, the starches had variations in brightness between 75.67 and 95.52,
chroma between 3.46 and 9.94, and Hue angle between 32.63 and 79.48. The amylose content
present in the starches varied between 28.50 and 38.50%. The viscosity profile showed
maximum viscosity peaks between 1314.5 and 2656.2 cP and minimum viscosity between 710
and 1086.3 cP. Paste temperatures varied between 67.1 and 68.4 C. The texture profile was
carried out, showing results of hardness between 1.95 and 6.62 N. The X-ray diffraction
analysis showed crystallinity results of starches between 15.10 and 21.02%. As for the thermal
properties analyzed via RVA, the samples presented initial temperature between 64.01 and
66.91 C, peak temperature between 70.19 and 73.09 C, and final temperature between 80.12
and 87.25 C to the enthalpies of gelatinization of the samples between 4.70 and 11.56 J/g.
Fourier Transform IR spectrometry analysis demonstrated that the starches are in their native
form. The SEM analysis showed that starches have spherical and polyhedral shapes, and some
extracted starches have several non-starch compounds and brittle granules. The antioxidant
content of the starches was analyzed using the DPPH discoloration method, highlighting the
BRS Ponta Negra type B sorghum starch with 64.24% discoloration. The other starches showed
percentages of discoloration between 2.26 and 6.25%, and the red type A commercial sorghum
starch did not obtain tangible results. The content of phenolic compounds was analyzed by the
Folin-Ciocalteu method. It was not possible to obtain results for starch from commercial red
sorghum, sorghum SSG150 T obtained content of 12.44 µg of gallic acid per ml, and starches
from BRS Ponta Negra sorghum type A and type B obtained, respectively, with contents of
0.11 and 63.23 µg of gallic acid per ml. Mass spectrometry analysis was performed using
catechin, quercetin, and gallic acid as standard, and the three compounds were identified in
extracts of all starches. Finally, principal component analysis (PCA) was performed using the
results found. The results show the potential for using sorghum starch in various branches of
the food industry, such as applications that require using natural dyes and foods enriched in
bioactive compounds.
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Citação
TELLES, A. D. M. Amidos de sorgos pigmentados com potencial para aplicação na indústria de alimentos. 2023. 83 f. Dissertação (Mestrado em Ciência e Tecnologia de Alimentos) - Universidade Federal de Goiás, Goiânia, 2022.