Search

To study the effects of hot air temperature and slice thickness on the drying characteristics, physicochemical properties and antioxidant components of Mulusasiatica Nakai slices. The Mulusasiatica Nakai slices with thickness of 3 mm and 5 mm were dried in the hot air temperature range of 60, 70, 80, 90 ℃. Five classical food thin layer drying models were used to nonlinear fit the experimental data, and the diffusion coefficient and activation energy were calculated. The color, hardness, rehydration properties and antioxidant components of the dried slices were analyzed. Results showed that, the drying time was obviously shortened with the increase of hot-air temperature and the decrease of slice thickness. In the experimental drying temperature range, the effective diffusion coefficient increased with the increase of temperature. The activation energies were 17.46 kJ/mol and 23.82 kJ/mol when the slice thickness was 3 and 5 mm, respectively. Fick diffusion model was used to describe the evaporation process of Mulusasiatica Nakai slices. Compared with other models, Page model could better fit the drying process of Mulusasiatica Nakai slices. When the slice thickness was 3 mm and the hot-air temperature was 90 ℃, the dried product was light yellow, with high rehydration performance and low hardness. In terms of antioxidant retention, heat lost about 50% of ascorbic acid, but only about 35% of total phenolics. In conclusion, the slice thickness could be selected to be 3mm, the hot air temperature 90 ℃ for drying, drying time 90 min, dried product color was light yellow, higher rehydration performance, lower hardness, and could better retain the antioxidant components in Mulusasiatica Nakai.

Drying kinetics of roots of Euphorbia condylocarpa M.Bieb. plant was studied. The root slices were dried at four temperature levels, also in shadow as control in three replications. The dried samples were considered for evaluation the total phenolic compounds (TPCs), free radical scavenging capacity inhibitory 2, 2-diphenyl-1-picrylhydrazyl, inhibiting gram-negative and gram-positive bacteria of Pseudomonas aeruginosa, and Staphylococcus aureus. The obtained results were compared with control treatments. The analysis of variance showed a significant difference in 1% level for the main effects of temperature, thickness, and their interaction on drying time, TPC and changes of inhibiting P. aeruginosa and Staphylococcus aureus. The results indicated that the highest content of total phenolic compounds were obtained at 40 °C, and 7 mm, and increasing the free radical scavenging capacity of 2, 2-diphenyl-1-picrylhydrazyl was achieved at 60 °C, and 7 mm. In addition, the highest inhibition zone values for the gram-positive bacterium of Staphylococcus aureus were obtained for the samples dried at 50 °C and thickness of 7 mm while the highest inhibition zone values for gram-negative bacterium of P. aeruginosa was obtained at 50 °C and 3 mm thickness. [ABSTRACT FROM AUTHOR]

Copyright of Science & Technology of Food Industry is the property of Science & Technology of Food Industry Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Chinese Institute of Food Science & Technology is the property of Journal of Chinese Institute of Food Science & Technology Periodical Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Mustafa Kemal University Journal of Agricultural Sciences / Mustafa Kemal Üniversitesi Tarım Bilimleri Dergisi is the property of Mustafa Kemal University, Faculty of Agriculture and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Microwave drying is a promising and effective way to drying and upgrading lignite. The influence of temperature (100–140 °C) and microwave power levels (500–800 W) on thin-layer drying characteristics of Zhaotong lignite under microwave irradiation were investigated. Fourteen thin-layer drying models were used to analyze the microwave drying process while six thin-layer drying models were used to analyze the hot-air drying process. The microwave drying processes at all temperature (100–140 °C) or low microwave power levels (500–700 W) exhibited four periods: a warm-up period, a short constant period, the first and second falling rate period, while one falling rate period was found during hot-air drying. The effective diffusion coefficient of lignite were calculated and it increases with increasing temperature and microwave power levels. During microwave drying, the two-term exponential model is the most suitable model for all applied conditions, while the Modified Page model is the most suitable model to describe the hot-air drying experiments. The apparent activation energy were determined from Arrhenius equation and the values for the first and second falling rate period are 3.349 and 20.808 kJ·mol−1 at different temperatures, while they are 13.455 and 19.580 W·g−1 at different microwave power levels. This implies the apparent activation energy is higher during the second falling rate period, which suggest that the dewatering of absorbed water is more difficult than capillary water. The value of apparent activation energy in hot-air drying is between the first and second falling rate period of microwave drying. Results indicate that microwave drying is more suitable to dewatering free water and capillary water of lignite. [ABSTRACT FROM AUTHOR]