• Journal of the Korean Society of Food Science and Nutrition
• /
• v.27 no.1
• /
• pp.87-92
• /
• 1998

Major characteristics of shrinking and rehydration of Korean tea-leaves were investigated in the hot-air drying equipment. Experiments were performed with various drying temperature, plucking time, heating method and rolling condition. The values of shrinking raito and rate were the highest at 7$0^{\circ}C$ in the range of 3$0^{\circ}C$ to 9$0^{\circ}C$. The 1st tea-leaves and showed higher values. Shrinking ratio was 16.62 and 19.62% for leaves and stems; shrinking rate was found 0.083 and 0.091cm/hr.cm, respectively. The rehydration characteristics of tea-leaves at the drying temperature of 3$0^{\circ}C$ were fairly satisfactory. The 2nd tea-leaves showed higher value than others, while the natural tea-leaves were lower. Average rehydration ratio and rehydration rate constant were 85.7% and 0.063/min for leaves; 80.1% and 0.032/min for stems, respectively.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.19 no.3
• /
• pp.195-200
• /
• 1990

Effects of cooking time(5-30 min in a pressure cooker) and HTST air dehydratiion time(0-9min at 15$0^{\circ}C$) on physical properties of dried green peas(3% oisture content wet basis) were investigated by determining rehydration ratio rehydration curve browning reaction and puncture force, The rehydration ratio and curve of dried green peas were increased with increa-sing cooking time and HTST air dehydration time. Preheating of the green peas for 30 min in a pressure cooker or for 9 min of HTST air dehydration time prior to 6$0^{\circ}C$ air dehydration recovered a 87.3% of original moisture content of raw green peas in a boiling water for 5 min. The brownin greaction was gradually decreased up to 15 min of cooking time. Puncture pressure of rehydrated green peas treated in a boiling water for 5 min was decreased as the cooking time and HTST air dehydration time were increased and was highly correlated with rehydration (r=-0.956) The effects of cooking time and HTST air dehydration time on rehydration ratio browning reaction and puncture pressure were significantly different at the a=0.01 level except effect of HTST air dehydration time on browning reaction.

• Preventive Nutrition and Food Science
• /
• v.14 no.4
• /
• pp.367-372
• /
• 2009

Apple, persimmon, and strawberry slices were dehydrated after treating with 30, 50, and 80% (w/w) maltodextrin solution. The dried apple, persimmon, and strawberry slices were compared with hot air-dried and freeze-dried samples in terms of rehydration ratio, ascorbic acid, color, and sensory evaluation. The rehydration ratio of maltodextrin-treated samples was greater than that of hot-air or freeze-dried samples. Maltodextrin-treated samples had higher content of ascorbic acid than other dried samples. Additionally, maltodextrin-treated apple, persimmon, and strawberry slices had better color and sensory evaluations than those of freeze-dried or hot-air dried samples. These results suggest that, compared to other drying methods, dehydration of apple, persimmon, and strawberry slices using maltodextrin is very efficient, resulting in good rehydration capacity, minimal destruction of ascorbic acid, and good color and sensory evaluation.

• Food Science of Animal Resources
• /
• v.41 no.1
• /
• pp.153-163
• /
• 2021

This study was conducted to examine the effects of starch noodles (dangmyeon; SNs) with different starch sources and porcine intestines (PIs) with different pH on the rehydration stability of Korean blood sausage (sundae). Mungbean SN3 and PI3 (pH 9.18) showed significantly higher values of 80.69%-91.67% and 79.66%-80.98%, respectively, regardless of the drying methods (hot air, vacuum and freeze drying) (p<0.05). A number of larger pores were observed only in the cross-section of the freeze dried SN and PI through SEM. SN2 (potato starch) and PI3 (pH 9.18) showed lower expansion (⁎ΔL 6.90 mm) and higher expansion ratio (⁎ΔL 26.29 mm), respectively, after rehydration of freeze dried sample (p<0.05). From the application of SN2 (potato starch) and PI (0.5%-2.0% Na-pyrophosphate) to freeze dried sundae manufacturing, higher rehydration stability of more than 91.5% was obtained. These results suggested that potato SN and treatment of PI with Na-pyrophosphate is useful for desirable rehydration stability of freeze dried sundae.

• Journal of the Korean Ceramic Society
• /
• v.35 no.10
• /
• pp.1085-1093
• /
• 1998

Amorphous alumina powder prepared by the fast calcination of aluminum trihydroxide(Al(OH)3 gibbsite) for 0.5 second at 580$^{\circ}C$ was investigated rehydration propeties. Phase composition crystal size and mor-phology surface area pore volume and pore size distribution of pesudo-boehmite and bayerite crystals changed with temperature time water/alumina ratio and particle size when amorphous alumina rehydrated with water. Phase compositions were examined with XRD and DTA and crystal sized morphologies were investigaed with SEM and TEM. Also rehydration properties of amorphous alumina were in-vestigated by measuring the surface area pore volume and pore size distribution.

• Korean Journal of Food Science and Technology
• /
• v.21 no.1
• /
• pp.145-148
• /
• 1989

Shiitake mushrooms were dried by hot air, far infrared and freeze dryers in order to compare qualities after drying. When hot air drying was performed with the four temperature variations ranged from $45\;to\;70^{\circ}C$, there was tendency to increase volume retention but decrease rehydration ratio, as drying temperature increased. And the largest amout of 5'-GMP was contained in mushroom dried at $50^{\circ}C$. For far infrared drying, volume retentions were lower but rehydration ratios were higher, as compared with hot air drying at the same temperature. In freeze drying, freezing rate had no influence on volume retention but rehydration ratio was highest value when frozen at $-18^{\circ}C$. As shelf temperature increased(drying rate increased), rehydration ratio increased. Also, contents of 5'-AMP, 5'-GMP and 5'-XMP increased with the increase of freezing rate and drying rate.

• Journal of Pharmaceutical Investigation
• /
• v.31 no.1
• /
• pp.43-47
• /
• 2001

Sterically stabilized liposomes (SSL) have been introduced for longer circulation in blood than conventional liposomes (CL). However, there are a couple of problems in SSL preparation due to the instability of phospholipid and the degradation of drug in aqueous conditions. To solve these problems, it is necessary to go through lyophilization process. Therefore, in this study, effects of lyophilization on SSL were evaluated for physical characteristics changes upon rehydration of lyophilized SSL such as the particle size, efficiency of drug entrapment, turbidity and drug release. SSL containing streptozocin, a water-soluble anticancer drug as a model compound, were prepared with DSPC and DSPE-PEG 2000. The size was controlled to 100 nm by extrusion with polycarbonate membrane, and sucrose was used as a cryoprotectant for lyophilization at the 1:3 (lipid:sucrose) ratio. Upon rehydration of lyophilized SSL, the average size was in the range of $50{\sim}200\;nm$ which is adequate for longer circulation in blood, and the encapsulation efficiency was kept as its initial state. Rehydrated SSL were not adsorbed to rat plasma protein and revealed a similar drug release profile to that of fresh SSL before lyophilization. Therefore, lyophilization could be introduced efficiently to overcome aqueous instability problems of SSL.

• Food Engineering Progress
• /
• v.21 no.1
• /
• pp.29-35
• /
• 2017

Quality changes of dried sea cucumber (Stichopusjaponicus) after applying a cyclic rehydration and retorting process were investigated during 4 weeks of storage. The length, volume, and weight of dried sea cucumber increased significantly as the number of rehydration cycles increased. Sea cucumber (SC) was bottled in the glass jar and a retort thermal process ($121.1^{\circ}C$, 0.15 MPa) was applied. The total thermal processing time (TTT) was 24 min based on the temperature at the cold point. The size and texture of retorted SC were significantly changed until the first week of storage. However, regardless of the number of rehydration cycles, the size and texture of samples at different rehydration cycles showed no significant difference during the whole storage. The length, volume, weight, rehydration ratio ($R_R$), hardness, and chewiness at the maximum degree of swelling during rehydration of dried SC were estimated as 100.86 mm, 38.62 mL, 41.05 g, 6.39 of $R_R$, $249.19g_f$, and 4.05 mJ, respectively.

• Food Engineering Progress
• /
• v.23 no.3
• /
• pp.217-222
• /
• 2019

The purpose of this study is to investigate the effect of ultra-fine powder kelp powder as a natural food additive for fast rehydration on the quality of freeze-dried fish cake noodle with soft and elastic texture properties during or after cooking. The average moisture content and water activity ranges of freeze-dried fish cake noodle were 3.71±0.12% (dry basis) and 0.185-0.332, respectively. The water activity of freeze-dried fish cake noodle decreased upon increasing the kelp powder content at the same moisture content. The rehydration ratios of fish cake noodle with 1, 3, and 5% (w/w) of kelp powder were 1.39, 1.49, and 1.77 g water/g solid, respectively. The hardness of the 5% (w/w) kelp powder-enhanced fish cake noodle after rehydration had the lowest value among the three samples upon using a texture profile analysis test (TPA). In the sensory hedonic test results, 5% (w/w) kelp powder added to fish cake noodle after rehydration produced the highest values in texture, flavor, and overall quality.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.39 no.7
• /
• pp.1024-1029
• /
• 2010

Opuntia ficus-indica and Aloe vera slices were dried using 20, 30, and 40% polyethylene glycol (PEG) 4,000 as a dehydration agent, and the dried samples were compared with the hot-air dried and freeze dried in terms of rehydration ratio, color, and sensory evaluation. The moisture content of the PEG-treated samples decreased with increasing concentrations of polyethylene glycol. The rehydration ratio of the PEG-treated samples was better than those of the hot air-dried or freeze-dried samples. The color of the PEG-treated samples was similar to that of the freeze-dried samples and better than that of the hot air-dried samples. The sensory evaluation of PEG-treated samples was better than those of the hot air-dried or freeze-dried samples. These results suggest that dehydration of Opuntia ficus-indica and Aloe vera slices using PEG is very effective in terms of rehydration ratio and minimal damage of cell structure.