45F-20 |
Thermal and functional properties of guava seed glutelins |
G. DAVILA-ORTIZ, Departamento de Graduados e Investigacion en Alimentos, ENCB-IPN, Prolongacion de Carpio y Plan de Ayala s/n, Col. Casco de Sto. Tomas, D.F., 11340, Mexico and A. Bernardino-Nicanor, Departamento de Graduados e Investigación en Alimentos, ENCB-IPN, Plan de Ayala y Prolongacion de Carpio s/n, Col Sto. Tomas, D.F., 11340, Mexico. Guava is one of the best-known tropical fruits, is widely distributed and requires no special care. In Mexico guava processing generates .4230 Ton seed/year, which is a potential protein and fat source. The thermal and functional properties of glutelins, majority proteins in the guava seed, were studied to determine its possible use as a food ingredient. Glutelin extracts were obtained with buffers (NaOH, Borate, Borate-SDS, Borate-bmercaptoethanol and Borate-SDS-bmercaptoethanol) and their thermal and functional properties were determined. Glutelin extract solubility evaluated with the Maruyama et al. (1999) method exhibited a characteristic inverted bell curve behavior with an interval inflection of 4-6 pH, increasing at both extremes of pH, with the alkaline side being greater. Guava seed glutelin emulsifying capacity, as determined with the method of Pearce and Kinsella (1978), was affected by the pH of the solution they were dissolved in. the extract obtained with NaOH exhibited the best emulsifying capacity. Emulsion stability (Takeda 2001) after one day decreased, remaining constant during the following two days. Thermal analysis of the guava seed glutelin extracts, as done with the method of Martínez E. and Añon (1996), exhibited 3 peaks with Td between 74.8 and 113.32ºC and a DH value in an interval of 0.3 to 2 J/g. The extracts obtained in the presence of b-mercaptoethanol only had two very similar Td peaks and a DH between 0.08 a 0.4 J/g. The obtained results suggest the presence of three different molecular forms, one of which may be stabilized by disulfide bonds.
Session 45F, Fruit & Vegetable Products: Fruits (Fresh)
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