Study on intermittent low‐pressure superheated steam drying: Effect on drying kinetics and quality changes in ripe mangoes
Pak Malaikritsanachalee, Withu Choosri, Touchpong Choosri
Abstract
The effect of intermittent low-pressure superheated steam drying (LPSSD) at 6.0 kPa of ripe mangoes was studied and compared with hot-air drying (HAD) at 70°C and 2.0 m/s. The heating:tempering periods (10:1, 20:1, and 30:1 min) were studied. The results showed that all drying curves were suitably fitted by the Page model. The drying time of LPSSD was shorter by 58% as compared to the HAD. The LPSSD-dried products were less color changes (p < .05), shrinkage (p < .05), and rehydration time than that of the HAD-dried products. Total color differences (ΔE*) and shrinkage of LPSSD-dried products were lower than HAD-dried products approximately 12.49 and 15.10%, respectively. The intermittent LPSSD-dried products at 20:1 min provided the highest porous structure and rehydration rate. There was no significant difference in kinetic, ΔE*, and S (p > .05) in all conditions of LPSSD. The intermittent LPSSD can be utilized to improve the productivity and quality of dried fruits. Practical applications Nowadays, the consumer demand for dried fruits is high nutritional values as well as the appearance which is most similar to fresh products. The major problem of the drying process on food products, especially HAD, is the product quality changes during the drying process due to the temperature and long drying time. The LPSSD is one of the interesting drying methods to preserve the quality of dried fruits. Therefore, the efficiency of HAD, continuous and intermittent LPSSD was demonstrated, including the quality changes in dried ripe mangoes. The results of this study provided information regarding the drying process (kinetics, drying behavior, drying rate, and Deff), including the qualitative properties (color, shrinkage, rehydration, and microstructure) of dried ripe mangoes. For the results, the intermittent LPSSD can be utilized to improve the productivity and quality of dried fruits in the food processing industry.