scholarly journals Non-enzymatic browning and flavour kinetics of vacuum dried onion slices

2015 ◽  
Vol 29 (1) ◽  
pp. 91-100 ◽  
Author(s):  
Jayeeta Mitra ◽  
Shanker L. Shrivastava ◽  
Pavuluri S. Rao
Keyword(s):  
Moisture Content ◽  
Colour Change ◽  
Enzymatic Browning ◽  
Vacuum Drying ◽  
Rehydration Ratio ◽  
High Quality ◽  
Optical Index ◽  
Hot Air ◽  
Colour Development ◽  
Kinetics Of

Abstract Onion slices were dehydrated under vacuum to produce good quality dried ready-to-use onion slices. Colour development due to non-enzymatic browning and flavour loss in terms of thiosulphinate concentration was determined, along with moisture content and rehydration ratio. Kinetics of non-enzymatic browning and thiosulphinate loss during drying was analysed. Colour change due to non-enzymatic browning was found to be much lower in the case of vacuum dried onion, and improved flavour retention was observed as compared to hot air dried onion slices. The optical index values for non-enzymatic browning varied from 18.41 to 38.68 for untreated onion slices and from 16.73 to 36.51 for treated slices, whereas thiosulphinate concentration in the case of untreated onion slices was within the range of 2.96-3.92 μmol g-1 for dried sample and 3.71-4.43 μmol g-1 for the treated onion slices. Rehydration ratio was also increased, which may be attributed to a better porous structure attained due to vacuum drying. The treatment applied was found very suitable in controlling non-enzymatic browning and flavour loss during drying, besides increasing rehydration ratio. Hence, high quality dried ready- to-use onion slices were prepared.

scholarly journals Process optimisation of vacuum drying of onion slices

2011 ◽  
Vol 29 (No. 6) ◽  
pp. 586-594 ◽  
Author(s):  
J. Mitra ◽  
S.L. Shrivastava ◽  
P.S. Rao
Keyword(s):  
Moisture Content ◽  
Numerical Technique ◽  
Colour Change ◽  
Vacuum Drying ◽  
Slice Thickness ◽  
Drying Process ◽  
Rehydration Ratio ◽  
Drying Temperature ◽  
Treated Sample ◽  
Full Factorial

Dehydration of untreated and pre-treated onion slices under vacuum was optimised using the response surface methodology. The effects of the drying temperature (50&ndash;70&deg;C), slice thickness (1&ndash;5 mm), and treatment (5% NaCl and 0.2% K<sub>2</sub>S<sub>2</sub>O<sub>5</sub>) were observed on the responses, viz. final moisture content, colour change, flavour content, and rehydration ratio of the dehydrated onion slices. Full factorial design was employed for the analysis. Optimisation of the vacuum drying process was achieved based on the criteria of maximum flavour retention, 3&ndash;3.5% db moisture content, acceptable colour, and rehydration ratio using numerical technique. The optimum condition for the treated sample was found at 58.66&deg;C drying temperature and 4.95 mm slice thickness. Optimum values of the response parameters, namely the moisture content, colour, flavour content, and rehydration ratio were obtained as 3.5% d.b., 30.33 OI/g dried sample; 4.35 &mu;mol/g dried sample and 4.82, respectively.

Mass Transfer Parameters and Modeling of Hot Air Drying Kinetics of Dill Leaves

2016 ◽  
Vol 12 (2) ◽  
Author(s):  
Hosain Darvishi ◽  
Zanyar Farhudi ◽  
Nasser Behroozi-Khazaei
Keyword(s):  
Activation Energy ◽  
Mass Transfer ◽  
Moisture Content ◽  
Moisture Diffusivity ◽  
Drying Kinetics ◽  
Transfer Model ◽  
Hot Air ◽  
Drying Behavior ◽  
Kinetics Of ◽  
Best Fit

Abstract Moisture diffusivity (Dem), mass transfer coefficient (hm), activation energy and drying kinetics of the dill leaves were studied and modeled as a function of temperature (40–70 °C) and moisture content (0.20–5.67 kg water/kg dry matter). Results showed that the Dem and hm significantly depend on the temperature and moisture content (p < 0.05). The average of Dem and hm varied between 4.02 × 10–9 to 9.65 × 10–9 m2/s, and 2.38 × 10–7 to 6.33 × 10–7 m/s, respectively. Activation energy showed a significant dependence on the moisture content and estimated as 16.84 kJ/mol for diffusion model and 28.70 kJ/mol for mass transfer model. Out of the six models considered, the logarithmic model showed the best fit to drying behavior of the dill leaves.

Multi-Objective Optimization and Quality Evaluation of Short- and Medium-Wave Infrared Radiation Dried Carrot Slices

2019 ◽  
Vol 15 (8) ◽  
Author(s):  
Qinqin Chen ◽  
Huihui Song ◽  
Jinfeng Bi ◽  
Ruijuan Chen ◽  
Xuan Liu ◽  
...  
Keyword(s):  
Moisture Content ◽  
Infrared Radiation ◽  
Quality Evaluation ◽  
Color Parameter ◽  
Rehydration Ratio ◽  
Carotene Content ◽  
Drying Time ◽  
Drying Temperature ◽  
Hot Air ◽  
Surface Method

AbstractOptimum technology and quality evaluation of short- and medium-wave infrared radiation (SMIR) dried carrot slices were studied. Effects of drying temperature, drying time and infrared power of SMIR drying on the moisture content, color parameter and β-carotene content of dehydrated carrot slices were investigated. The experimental data were well predicted by a modified second-order polynomial model. Drying temperature and drying time had significant effects on moisture content, color parameter and β-carotene content. However, infrared power only showed significant effect on the moisture content. Response surface method (RSM) was used for optimization of SMIR drying of carrot slices, and the optimum condition was found as drying time of 50 min, infrared power of 1125 W, and drying temperature of 70 °C. SMIR dried products were proved to be favorable by comparing with hot-air dried ones due to its higher rehydration ratio (6.89) and β-carotene content (462.48 μg/g).

Drying characteristics and bioactivity evolution of Platycodon grandiflorum as affected by different microwave combined drying methods

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Yuan-Yuan Liu ◽  
Wei-Qiao Lv ◽  
Ruo-Hui Lin ◽  
Dong Li ◽  
Li-Jun Wang
Keyword(s):  
Reaction Model ◽  
Vacuum Drying ◽  
Drying Methods ◽  
Rehydration Ratio ◽  
Hot Air Drying ◽  
Drying Characteristics ◽  
Platycodon Grandiflorum ◽  
Microwave Vacuum Drying ◽  
Hot Air ◽  
Drying Technology

Abstract This study was to investigate the effect of different drying methods on the drying kinetics, physical properties, and bioactivity of Platycodon grandiflorum (PG). Four drying methods were employed to conduct the dehydrated process, namely, hot air drying (AD), vacuum drying (VD), microwave hot airflow rolling-bed drying (MHARD), and pulse-spouted microwave vacuum drying (PSMVD). PSMVD showed the highest drying rate among four drying methods based on the result of fitting first-order reaction model. And PSMVD-dried product showed higher rehydration ratio and better mechanical properties, suggesting a better rehydration characteristic. In addition, considering the content of Platycodin D, PSMVD is a promising drying technology for the dehydration of PG.

scholarly journals INVESTIGATING ON EFFECT OF HOT AIR AND WATER TEMPERATURE ON KINETIC OF REHYDRATION OF CELERY BY USING PELEG’S MODEL

2019 ◽  
Vol 49 (4) ◽  
pp. 249-254
Author(s):  
Azadeh Salimi ◽  
Haniyeh Ameri ◽  
Atefe Hajigorbani
Keyword(s):  
Moisture Content ◽  
Water Temperature ◽  
Absorption Capacity ◽  
Water Absorption Capacity ◽  
Hot Air ◽  
Peleg Model ◽  
Experimental Values ◽  
Drying Conditions ◽  
Kinetics Of ◽  
Determine Effect

The Peleg model was used to determine effect of drying conditions and rehydration water temperature on kinetic of moisture content and rehydration ration changes of celery. Celery cubes (1×1×1 cm) were dried at 65ºC in hot air oven. Samples were rehydrated by immersion in water during different periods of time and temperatures (25±2ºC and 100±2ºC). Rehydration kinetic was monitored by measuring samples' weights at regular intervals. Results showed that the highest final moisture content which was observed belonged to the samples which were dried at 70 °C and reydrated at 25°C water temperature, also, dried celeries which were rehydrated at a water temperature of 25°C, had higher levels of RR as a function of physical properties. The Peleg’s e constant (K1), decreased significantly while water temperature increased and in case of the Peleg capacity constant (K2), it increased slightly while water temperature increased. Decreasing of K2 values is a sign of more water absorption capacity. Finally, it was observed that the predicted and experimental values had a good correlation which indicates that the Peleg model is adequate to describe rehydration kinetics of celery cubes.

Diffusion of Water in Chestnut Fruits during Drying and Rehydration Processes at Different Temperatures

2008 ◽  
Vol 273-276 ◽  
pp. 758-763
Author(s):  
Ramón Moreira ◽  
Francisco Chenlo ◽  
L. Chaguri ◽  
Christiana Fernandes
Keyword(s):  
Moisture Content ◽  
Initial Moisture Content ◽  
Convective Drying ◽  
Transfer Processes ◽  
Hot Air ◽  
Mass Transfer Processes ◽  
Different Temperatures ◽  
Diffusional Model ◽  
Kinetics Of

Many food materials must be dried in order to decrease its water activity and to increase the shelf-life. Also, rehydration operation must be carried out as previous step before consumption. Both operations are commonly employed in some industrial chestnut processing. These processes can be carried out at different temperatures and in all cases the quality of the final product can be affected. In this work, convective drying with hot air is the employed method for water removal and rehydration is carried out by immersion of chestnut in water. In both cases, mass transfer processes are governed by water diffusion in the bulk of the solid. The aim of this work is to determine experimentally the drying and rehydration kinetics of chestnut samples at different conditions of temperature and moisture content. Obtained data are modeled with a diffusional model taking into account volume variations and the corresponding values of the coefficients of diffusion of water are obtained. Analysis of the results indicates that drying/rehydration rates increase with temperature and rehydration kinetics are also depending on the initial moisture content of chestnut. Finally, leaching flow during rehydration is only important at high temperature due to starch gelatinization processes.

scholarly journals Kinetics of non-enzymatic browning reaction from the l-ascorbic acid/l-cysteine model system

2016 ◽  
Vol 34 (No. 6) ◽  
pp. 503-510 ◽  
Author(s):  
A.-N. Yu ◽  
L.-P. Tang
Keyword(s):  
Ascorbic Acid ◽  
Order Reaction ◽  
Model Systems ◽  
Enzymatic Browning ◽  
Ascorbic Acid Concentration ◽  
First Order ◽  
Browning Reaction ◽  
Brown Colour ◽  
Colour Development ◽  
Kinetics Of

The kinetics of the non-enzymatic browning reaction from l-ascorbic acid/l-cysteine model systems was investigated at 125–155°C for 10–120 min by measuring the loss of reactants and monitoring the brown colour development. The result showed that the browning products were produced at the first order reaction kinetics requirement, with the E<sub>a</sub> being 114.33 kJ/mol. The mechanism for the browning development was proposed. The correlation coefficient between browning products and uncoloured intermediate products increased with the rising temperature. At temperatures below 110°C, the non-enzymatic browning reaction did not occur at all or the reaction was slow. Browning products could not be produced solely by self-degradation of l-cysteine. The amount of browning products negatively correlated with the l-ascorbic acid concentration.

Kinetics of Microwave Vacuum Drying of “Cat Chu” Mango in Mekong Delta - Vietnam

2015 ◽  
Vol 656-657 ◽  
pp. 573-579 ◽  
Author(s):  
Cuong Nguyen Van ◽  
Hau Tran Tan
Keyword(s):  
Mekong Delta ◽  
Convective Drying ◽  
Vacuum Drying ◽  
Second Phase ◽  
High Quality ◽  
Hot Air Drying ◽  
Drying Time ◽  
Air Drying ◽  
Microwave Vacuum Drying ◽  
Hot Air

Microwave vacuum drying is one of innovative drying techniques that is today used in drying of foods, medical products and other high quality products. In this drying technology, heat is generated by directly transforming the electromagnetic energy into kinetic molecular energy of water, thus the heat is produced deep within the material to be dried under vacuum environment. This paper presents the results of research on microwave vacuum drying of “Cat Chu” mango in Mekong Delta – Vietnam. “Cat Chu” mango, with moisture content of (80 ± 1) % (wet basis - wb), was sliced into 5 cm thickness, and was dried in mWaveVac0150-lc dryer (Püschner - Germany). The drying vacuum was from 60 to 120 mbar. Three levels of microwave power were established: the first phase from 600 to 800 W, the second phase from 300 to 500 W, the last one from 150 to 250 W. The control sample was dried by convective drying method at 60 °C; and vacuum drying at 70 mbar, 60 °C. The results of this research showed that high quality product in terms of color, surface shrinkage and structure was obtained by microwave vacuum drying. The drying time was about 45 min, 450 min and 870 min with microwave vacuum drying, vacuum drying and convective hot-air drying, respectively. In addition, Fick’s equation and Crank’s solution were applied to analyze and calculate the accessibility and diffusion coefficient of microwave vacuum drying process. Starting accessibility of process was significantly increased; the diffusivity obtained was within a range from 6.44*10-10 m2/s to 16.16*10-10 m2/s. The results also indicated that there was a higher exchange in surface and a greater internal diffusion of experimental microwave vacuum drying samples compared to the control vacuum and hot-air drying samples.

scholarly journals Comparative quality assessment of different drying procedures for plum fruits (Prunus domestica L.)

2017 ◽  
Vol 35 (No. 5) ◽  
pp. 449-455 ◽  
Author(s):  
Akhijahani Hadi Samimi ◽  
Arabhosseini Akbar ◽  
Kianmehr Mohammad Hossein
Keyword(s):  
Colour Change ◽  
Drying Methods ◽  
Prunus Domestica ◽  
Air Velocity ◽  
Rehydration Ratio ◽  
Hot Air Drying ◽  
Hot Air ◽  
Drying Procedures ◽  
Different Levels

Different drying methods for plum fruits were compared in this case study. Samples were dried at a temperature of 70°C using the method of hot air drying as well using hybrid solar drying at three levels of air velocity (0.5, 1, and 2 m/s) and open sun drying. The dried samples were then compared on the basis of changes in colour, shrinkage and rehydration. The effect of air velocity on colour change was significant (P &lt; 0.05) at the three different levels (0.5, 1, and 2 m/s), whereas effects on shrinkage and rehydration ratio were not significant (P &lt; 0.05). The best conditions for plum drying with respect to values of colour change, shrinkage, rehydration ratio and the drying costs were obtained for the plums dried using a hybrid solar dryer at an air velocity of 1 m/s.

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