Navegando por Assunto "Proteína"

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Acesso aberto (Open Access)
Estruturas supramoleculares de α-lactoalbumina e glicomacropeptídeo: produção, caracterização, propriedades funcionais e carreamento de vitamina B2 e quercetina
(Universidade Federal do Pará, 2016-03-01) DINIZ, Renata Silva; SILVA, Luiza Helena Meller da; http://lattes.cnpq.br/2311121099883170
This study aimed to produce, characterize and verify the technical and functional properties of α-lactalbumin (α-la) and glycomacropeptide (GMP) supramolecular structures, and their potential in the food industry. The α-la/GMP supramolecular structures were prepared in a molar ratio of 1: 0.689, respectively. This proportion was defined by isothermal titration calorimetry and differential scanning calorimetry aided in determining the temperature values used since the formation of supramolecular structures was verified at higher and lower values than the denaturation temperature of the α-la. For GMP could not be established denaturation temperature, because it has no defined tertiary structure. The circular dichroism and fluorimetry analysis showed that there was interaction between α-la and GMP molecules. The supramolecular structures, in general, kept the α-helix secondary structures, but the intensity of these secondary structures may vary in the different conditions tested. The supramolecular structures have hydrophobic core. The particle size of supramolecular structures ranging from nano to micrometer, demonstrating that can be controlled through variables tested: pH (3.5 to 6.5) Heating temperature (25 to 75 °C) and heating time. The stability of supramolecular structures was evaluated by monitoring the particle size and the ζ potential at temperatures of 4 and 25 °C for 60 days. The supramolecular structures formed at pH 6.5 have higher system stability with ζ potential absolute values of approximately -30 mV. The morphology of supramolecular structures was determined by transmission electron microscopy and it was observed that proteins associated forming spherical structures. The foaming ability of supramolecular structures was evaluated by homogenization method, determining the increased volume, stability and expansion of the foam. It was found that the structures formed at pH 6.5 and 75 °C showed higher foaming ability. The emulsifying properties of the supramolecular structures were determined by the emulsifying activity index and emulsion stability index, using the turbidimetric method. However, the variables tested (pH, temperature and time) showed no effect on emulsifying properties. The surface tension of the supramolecular structures, determined by the Wilhelmy method showed a mean value of 50.825 mNm-1, demonstrating that the supramolecular structures can be effective in stabilizing emulsions and foam products. The supramolecular structures were able to encapsulate quercetin and vitamin B2, with maximum encapsulation efficiency of 98.64% and 31.11%, respectively. The stability of carrier systems was evaluated by monitoring the particle size and ζ potential for 60 days. For quercetin, systems prepared at pH 6.5 were stable for 60 days, while for vitamin B2, the stability of 60 days was demonstrated by the systems prepared at pH 3.5.
Acesso aberto (Open Access)
Estudo da conservação mínima para as folhas da mandioqueira (manihot esculenta) e da obtenção de concentrados protéicos por três vias químicas
(Universidade Federal do Pará, 2022-10-17) MORAES, Jaqueline de Fátima Cabral; PENA, Rosinelson da Silva; http://lattes.cnpq.br/3452623210043423
Cassava is a raw material with remarkable role in the national agricultural scenario, which generates employment and income in all regions of the country. The use of this agricultural product is integral, due to its great versatility. The root is used for food, animal feed and for the flour, starch and energy industries; the aerial part (leaves and stems) can be used for human food (flour from the leaf) and animal feed. In this context, the aim of this thesis was to evaluate the potential products derived from the leaves of mandioqueira root, in order to versify its use as well as to promote the valuation of this fraction in the raw material. The first chapter of the thesis presents a literature review, which portrays the subjects that are raised in the following chapters. Chapters from II to VI present the experimental data obtained in this research. In the second chapter, it was evaluated the use of leaves as a minimally processed product for transport, as well as its storage under controlled conditions of temperature and atmosphere. In the third chapter, it was studied the chemical composition, physicochemical properties and proteins fractionation of the leaves from the raw material (Manihot esculenta), based on the Osborne procedure, where different solvents were applied to fractionate the proteins through changes in solubility that these protein leaves present. From this, it was performed in chapters IV, V and VI, the extraction of proteins, applying three different chemical pathways to obtain concentrate. These conditions allowed the development of the second and third manuscripts. For the extraction process, there were used: factorial design (BoxBehnken), response surface methodology, and the desirability function, which were applied to define the optimal conditions for the proteins of mandioqueira, in all routes (extraction by organic solvent, extraction under acid conditions and extraction under alkaline conditions). The lyophilized protein concentrates obtained in the three pathways were characterized. The total phenolic contents, total flavanols, chlorophyll a,chlorophyll b, and total carotenoids were determined; the colorimetric parameters were performed. Crude protein content, protein extraction yield and protein concentrate yield were quantified. Technological properties of this concentrate were determined through water absorption capacity and oil absorption capacity. The evaluation of these responses allowed the definition of the optimum process condition for each route of extraction, by the desirability function. Consequently, a monitoring of the extraction process was made, which was considered a process in permanent regime, presenting four stages: two inlet (fresh leaf and extraction solution) and two outlet (fibrous residue and lyophilized protein concentrate); whose control was possible by recording the mass (g), dry matter (g/100 g), crude protein (g dry basis) and moisture (%). The three lyophilized protein concentrates derived from the conditions of desirability were evaluated hygroscopically, by means of moisture sorption isotherms at 25 ºC. The studies carried out with mandioqueira are promising, because from them, it was possible to deepen forms of production and transformation of this raw material; factors that can influence directly or indirectly and positively in the social dimensions, environmental, cultural and economic of the region, and consequently promote the valorization of a regional raw material, either by trying to popularize other forms of use or by deepening knowledge about it.