Physicochemical Properties, Steady and Dynamic Rheological Measurements of Sour Guava (Psidium araca) Pulp
Luis Mieles-Gómez, Somaris Elena Quintana Martinez
and Luis Alberto García-Zapateiro*
Research Group of Complex Fluid Engineering and Food Rheology, University of Cartagena, Cartagena, Colombia.
Corresponding Author E-mail: lgarciaz@unicartagena.edu.co
Abstract:
Sour guava (Psidium araca) is a tropical fruit of the tropical region, recognized for its typical taste and nutritional composition. This work aimed to investigate how temperature affects the physicochemical and rheological characteristics of the sour guava pulp subjected to controlled scalding conditions. Physicochemical properties of fresh and scalded pulp were analyzed. Rheological analyses of steady shear rate in function of temperature (5 - 80 ºC) and viscoelastic properties were done. Scalding process did not affect the physicochemical properties (total acidity, soluble solids, pH, and maturity index) of the pulp, nevertheless, a 30% decrease in total phenolic compounds was observed. Pulps exhibit a non-Newtonian behavior type shear thinning described by using the Herschel-Bulkley model (R2 > 0.970). The influence of temperature was described by an Arrhenius-type equation on the pulp consistency index. The pulps displayed characteristics of a weak gel, where the storage modulus surpassed the loss modulus. A power function of the oscillatory frequency accurately described the storage and loss moduli, indicating elastic properties. The results showed that the sour guava pulp is suitable for use as a raw material for the development of processes for the manufacture of food products.
Keywords:
Sour guava (Psidium araca); Rheology; Shear Thinning; Viscoelasticity.
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