Extração e caracterização do amido de lobeira (solanum lycocarpum)
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2014-03-28
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Universidade Federal de Goiás
Resumo
This study was conducted to evaluate the chemical, physical-chemical,
biochemical and rheological properties of starch from Solanum lycocarpum. The
pulp from Solanum lycocarpum fruits was used as raw material for extraction of
starch, resulting in a yield of 51%. The starch granules were heterogeneous in
size, presenting a conical appearance, very similar to those from high-amylose
cassava starch. The elemental analysis (CHNS) revealed 64.33% carbon,
7.16% hydrogen and 0.80% nitrogen. FT-IR spectroscopy showed the peaks
characteristic of polysaccharides and NMR analysis confirmed the presence of
the α-anomer of D-glucose. The S. lycocarpum starch was characterized by
high value of intrinsic viscosity (3515 mPa s) and estimated molecular weight
around 645.69 kDa. Furthermore, this starch was classified as a C-type and
high amylose content starch, presenting 34.66% of amylose and 38%
crystallinity. Endothermic transition temperatures (To = 61.25°C; Tp = 64.5°C;
Tc = 67.5°C), gelatinization temperature (∆T = 6.3°C) and enthalpy changes
(∆H= 13.21 J g−1) were accessed by DCS analysis. The thermogravimetric
analysis of S. lycocarpum starch showed a typical three-step weight loss
pattern. Microscopy revealed significant changes in the granule morphology
after thermal treatment. Samples treated at 50°C for 10 min lost 52% of their
crystallinity, which was partially recovered after storage for 7 days at 4°C.
However, samples treated at 65°C for 10 min became were totally amorphous.
This treatment was sufficient to completely disrupt the starch granule, as
evidenced by the absence of an endothermic peak in the DSC thermogram. The
RVA of S. lycocarpum starch revealed 4440.7 cP peak viscosity, 2660.5 cP
breakdown viscosity, 2414.1 cP final viscosity, 834.3 cP setback viscosity, and
a pasting temperature of 49.6°C. The low content of resistant starch (10.25%)
and high content of digestible starch (89.78%) in S. lycocarpum suggest that
this starch may be a good source for the production of hydrolysates, such as
glucose syrup and its derivatives. These results make the S. lycocarpum fruit a
very promising source of starch for biotechnological applications.
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Solanum lycocarpum , Amilose , Amilopectina , Cristalinidade , Propriedades de pasta , Retrogradação , Propriedades térmicas , Amido resistente , Digestibilidade , Solanum lycocarpum , Amylose , Amylopectin , Crystallinity , Pasting properties , Retrogradation , Thermal properties , Resistant starch , Digestibility
Citação
PASCOAL, Aline Mendonça. Extração e caracterização do amido de lobeira (solanum lycocarpum). 2014. 69 f. Tese (Doutorado em Biologia) - Universidade Federal de Goiás, Goiânia, 2014.