| Popis: |
Las propiedades reológicas de los jugos de fruta dependen de su variedad, estado de madurez, concentración de jugo/pulpa y variación de temperatura; los valores de índice de comportamiento al flujo e índice de consistencia son limitados, considerando la cantidad de variedades de guayaba. En este trabajo se caracteriza reológicamente la pulpa de guayaba (Psidium guajava L.) en las variedades Híbrido de Klom Sali, Puerto Rico, D14 y Red, cultivadas en el departamento de Córdoba (Colombia); las pulpas son obtenidas mediante refinadora con malla 1.5mm de abertura. Las medidas reológicas se realizan en un viscosímetro Brookfield modelo DV-II+ Pro, utilizando la aguja Nº 5 para las variedades Klom Salí, Puerto Rico y Red, y Nº 6 para la variedad D14. Las pulpas de guayaba presentan pH entre 3.9-4.6, ºBrix entre 9-10, acidez titulable expresada como porcentaje de ácido cítrico entre 0.56-0.96%, e índice de madurez entre 9.38-17.94; su comportamiento reológico se ajusta adecuadamente al modelo de Oswald de Waele o ley de potencia (R²≥ 0.989), comportándose como un fluido seudoplástico (n ≤ 0.307) y presentando tixotropía las variedades Puerto Rico (14.16%), Red (18.54%) y D14 (18.48%).Rheological properties of fruit juices appear to be very much dependent of their varieties, state of ripening, concentration of juice/pulp and temperature variation. Typical values of flow behaviour index and consistency index are rather limited considering the varieties of guava fruits. In this work the guava pulp (Psidium guajava L.) was rheologically characterized in the varieties Hybrid of Klom Sali, Puerto Rico, D14 and Red cultivated in the department of Córdoba (Colombia); the pulps were obtained by means of refinery with mesh 1.5mm of opening. The rheological measurements were carried out in a Brookfield viscometer DV-II+ Pro model, used the spindle Nº 5 for the varieties Klom Sali, Puerto Rico and Red, and Nº 6 for the variety D14. The pulps presented pH among 3.90 - 4.6, ºBrix among 9 - 10, acidity expressed as percentage of citric acid among 0.56 - 0.96% and maturity index among 9.38-17.94; were adjusted appropriately to Oswald-de Waele model or power law (R²≥ 0.989), behaving as a pseudoplastic fluid (n ≤ 0.307) and presenting tixotropic percentages the variety Puerto Rico (14.16%), Red (18.54%) y D14 (18.48%). |
