Cristian Tapia

Bio: Cristian Tapia is an academic researcher from University of Chile. The author has contributed to research in topics: Chitosan & Membrane. The author has an hindex of 24, co-authored 50 publications receiving 2025 citations.

Study of Some Physicochemical and Functional Properties of Quinoa (Chenopodium Quinoa Willd) Protein Isolates

Abstract: The amino acid composition and the physicochemical and functional properties of quinoa protein isolates were evaluated. Protein isolates were prepared from quinoa seed by alkaline solubilization (at pH 9, called Q9, and at pH 11, called Q11) followed by isoelectric precipitation and spray drying. Q9 and Q11 had high levels of essential amino acids, with high levels of lysine. Both isolates showed similar patterns in native/SDS-PAGE and SEM. The pH effect on fluorescence measurements showed decreasing fluorescence intensity and a shift in the maximum of emission of both isolates. Q9 showed an endotherm with a denaturation temperature of 98.1 degrees C and a denaturation enthalpy of 12.7 J/g, while Q11 showed no endotherm. The protein solubility of Q11 was lower than that of Q9 at pH above 5.0 but similar at the pH range 3.0-4.0. The water holding capacity (WHC) was similar in both isolates and was not affected by pH. The water imbibing capacity (WIC) was double for Q11 (3.5 mL of water/g isolate). Analysis of DSC, fluorescence, and solubility data suggests that there is apparently denaturation due to pH. Some differences were found that could be attributed to the extreme pH treatments in protein isolates and the nature of quinoa proteins. Q9 and Q11 can be used as a valuable source of nutrition for infants and children. Q9 may be used as an ingredient in nutritive beverages, and Q11 may be used as an ingredient in sauces, sausages, and soups.

Quinoa protein–chitosan–sunflower oil edible film: Mechanical, barrier and structural properties

Abstract: Quinoa protein extracts (Q) were prepared and alkalised at pH 8 and 12 (Q-8 and Q-12). Qs were mixed with chitosan (CH) to form Q/CH mixtures. The optimal proportion of the mixtures was determined by the formation of coacervates. All the films were obtained by solution casting. From the optimal Q/CH mixture and the addition of three different concentrations of sunflower oil (SO) 2.9, 3.8 and 4.7 g/100 mL, and the optimal proportion of SO g/100 mL was selected based on the mechanical and barrier properties of the films. The CH, Q/CH and Q/CH/SO optimal blend films were characterised by FTIR, X-ray diffraction, and SEM. The physicochemical properties of the films were also evaluated. The 0.1 Q-8/CH blend was selected due to its high degree of interaction between the quinoa proteins and CH. The optimum concentration of SO used in the Q-8/CH/SO film was 2.9 g/100 mL. The addition of SO to the film improved the water-vapour permeability (WVP) as a result of hydrophobic interactions and the presence of clusters of hydrophobic masses on the surfaces of these films but reduced the film’s tensile strength and oxygen permeability due to the formation of micropores and microfractures detected by SEM.