Alimentos e Nutrição Araraquara, Vol. 16, No 4 (2005)

Tamanho da fonte:  Menor  Médio  Maior

Osmotic dehydration kinetics of guavas in maltose solutions with calcium salt*

S. DI S. MASTRANTONIO, L. M. PEREIRA, M. D. HUBINGER

Resumo



The osmotic dehydration kinetics of guavas in maltose solutions at 40 and 60ºBrix, with addition of 0, 0.6 and 1.2% of calcium lactate was studied in this paper and the final product quality was evaluated. The experiments were carried out up to 60 hours and samples were taken for analysis at different times to evaluate guavas weight reduction, water loss and sugar gain and to characterize the product according to its texture and color. After 24 hours of process the mass transfer of water and sugar between the osmotic solution and the fruit was negligible, showing that process equilibrium was reached. The increase of sugar concentration in the osmotic solution showed strong influence on the dehydration process, increasing the water loss and reducing sugar gain. The presence of calcium ions in the osmotic solution also influenced the kinetics of mass transfer and showed a strong influence on fruit texture. Higher values of stress and strain at failure were obtained when calcium lactate was employed. The effect of the different osmotic treatments on the color parameters was also investigated and significant changes were observed in the values of chroma C* and hue H* due to sugar concentration and calcium addition.



KEYWORDS: Osmotic dehydration; kinetics; guava; maltose; calcium lactate.


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