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Effect of Vacuum Drying Temperature on Drying Kinetics, Effective Moisture Diffusivity and Quality of Peeled Litchi ( Litchi chinensis Sonn.)
Author(s) -
Richter Reis Felipe,
Ivahashi Marcela Massumi,
Guéniat Rosa Aluísio Henrique
Publication year - 2017
Publication title -
journal of food process engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.507
H-Index - 45
eISSN - 1745-4530
pISSN - 0145-8876
DOI - 10.1111/jfpe.12419
Subject(s) - thermal diffusivity , moisture , shrinkage , water content , lightness , chemistry , dried fruit , water activity , food science , vacuum drying , flavor , materials science , freeze drying , thermodynamics , composite material , chromatography , physics , geotechnical engineering , optics , engineering
This study aimed at investigating the effect of vacuum drying temperature on drying kinetics, drying rates, effective moisture diffusivity and quality parameters of litchi fruits. Peeled litchi quarters were dried at 50–70 °C at an absolute pressure of 8 kPa. Results show that the vacuum drying occurred in the falling rate period. Drying rates increased with drying temperature. The Page model provided the best fit to the drying kinetics. Effective moisture diffusivity ranged between 1.997 × 10 −9 and 5.012 × 10 −9 m 2 /s. The temperature dependence of the effective moisture diffusivity was well described by an Arrhenius‐type equation. The activation energy for moisture diffusion was 41.81 kJ/mol. Drying temperature did not significantly affect product sensory acceptance, density, shrinkage and rehydration. The products dried at 50 and 70 °C presented slightly superior texture and flavor, while the product dried at 60 °C presented significantly higher lightness and lower water activity. Practical Applications This work provides valuable information on the vacuum drying of litchi fruits, which are appreciated in many countries due to their pleasant sensory characteristics. Vacuum drying is not a costly drying method. At the same time, vacuum drying produces dried foods of relatively good quality. This study could be used as a reference by small and medium scale food processors interested in producing dried litchi of good quality with relatively low investment in equipment. The understanding of the influence of drying temperature on quality parameters is useful for deciding which temperature is more appropriate depending on the desired quality aspects, while the calculation of engineering parameters is important for designing the drying process.