Food Science and Technology (Campinas)
On-line version ISSN 1678-457X
FONTANARI, Gustavo Guadagnucci et al. Protein isolate of guava seed (Psidium guajava): functional properties of characterization. Ciênc. Tecnol. Aliment. [online]. 2007, vol.27, suppl.1, pp. 73-79. ISSN 1678-457X. http://dx.doi.org/10.1590/S0101-20612007000500013.
Protein isolates (PIs) were obtained from the guava seed flour (Psidium guajava) by extracting different pHs followed by isoelectric precipitation (pH 4.5). The conditions for preparation of the PIs were defined from the solubility curve at pH 10.0 and 11.5, in the absence of NaCl and a temperature of 25 ± 3 ºC. These conditions obtained protein isolated (PI) with extraction yield of 45.19 and 66.23%, with protein content of 96.4 and 93.5% for PI 10.0 and 11.5, respectively. The water and oil absorption capacity of 1.05 ± 0.07 and 2.30 ± 0.01 mL.g -1 protein and 1.65 ± 0.07 and 1.70 ± 0.07 mL.g -1 protein, respectively; were obtained for PI 10.0 and PI 11.5. Differences among the PIs regarding the emulsion activity and stability were not observed, reaching similar and higher values compared to IP of other seeds. The gel formation in neutral pH and salt absence require concentrations of 8 and 10% to PI 10.0 and PI 11.5, respectively. The highest foam formation was observed for PI 10.0 in neutral and alkaline pH, and it showed a capacity of up to 90% of the initial volume; however for the foam stability both IPs showed good properties of up to two hours after foam formation.
Keywords : Psidium guajava; guava seed; functional properties; protein isolate (PI).