scholarly journals Effect of the Freeze-Drying Process on the Physicochemical and Microbiological Properties of Mexican Kefir Grains

Processes ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 127 ◽  
Author(s):  
Alicia Conde-Islas ◽  
Maribel Jiménez-Fernández ◽  
Denis Cantú-Lozano ◽  
Galo Urrea-García ◽  
Guadalupe Luna-Solano
Keyword(s):  
Moisture Content ◽  
Water Activity ◽  
Freeze Drying ◽  
Survival Rates ◽  
Freezing Temperature ◽  
Freezing Time ◽  
Residual Moisture Content ◽  
Drying Process ◽  
Residual Moisture ◽  
Kefir Grains

The purpose of this study was to investigate how the properties of Mexican kefir grains (MKG) are affected by the operating parameters used in the freeze-drying process. The factors investigated were the freezing time (3–9 h), freezing temperature (−20 to −80 °C), pressure (0.2–0.8 mbar), and lyophilization time (5–20 h). The maximum range of change and one-way analysis of variance showed that lyophilization time and freezing time significant affects (p < 0.05) the response variables, residual moisture content and water activity, and pressure had a significant effect on the color difference and survival rate of probiotic microorganisms. The best drying conditions were a freezing time of 3 h, a freezing temperature of −20 °C, a pressure of 0.6 mbar, and a lyophilization time of 15 h. Under these conditions, we obtained a product with residual moisture content below 6%, water activity below 0.2, and survival rates above 8.5 log cfu per gram of lactic acid bacteria and above 8.6 log for yeast.

Influence of Freeze-Drying Modes on the Quality of Live Plague Vaccine

2019 ◽  
Vol 35 (4) ◽  
pp. 73-78
Author(s):  
S.E. Gostischeva ◽  
D.V. Rostovtseva ◽  
G.F. Ivanova ◽  
A.V. Kostrominov ◽  
M.V. Pilipenko
Keyword(s):  
Heating Rate ◽  
Freeze Drying ◽  
Eutectic Point ◽  
Freezing Temperature ◽  
Freezing Time ◽  
Residual Moisture ◽  
High Viability ◽  
Plague Vaccine ◽  
Selection Of

The optimization of the drying schedule has been carried out to improve the quality indicators of the live plague vaccine. Based on the data obtained on the eutectic point of the vaccine suspension, the freezing temperature and freezing time were set to -50 °С and 6-7 h, respectively. A pressure of 40 mTorr over the surface of the drying suspension and 20 mTorr during the desorption were shown to be the best conditions for sublimation. The drying tests with different options for the shelf heating rate, vacuum depth and duration of intermediate temperature indicators were carried out to develop the improved freeze-drying mode providing the selection of the most adapted bacteria. A vaccine lyophilized under the developed conditions has low residual moisture (up to 2%) and high viability index that persists over the whole shelf life. lyophilization, sublimation, eutectic, live plague vaccine, residual moisture, viability

scholarly journals Viability of Bifidobacterium Pseudocatenulatum G4 after Spray-Drying and Freeze-Drying

2010 ◽  
Vol 3 ◽  
pp. MBI.S2728 ◽  
Author(s):  
Stephenie Wong ◽  
Barka Mohammed Kabeir ◽  
Shuhaimi Mustafa ◽  
Rosfarizan Mohamad ◽  
Anis Shobirin Meor Hussin ◽  
...  
Keyword(s):  
Spray Drying ◽  
Freeze Drying ◽  
Skim Milk ◽  
The Other ◽  
Outlet Temperature ◽  
Residual Moisture Content ◽  
Drying Process ◽  
Residual Moisture ◽  
Heat Adaptation ◽  
C 30

Viability of Bifidobacterium pseudocatenulatum G4 following spray-drying and freeze-drying in skim milk was evaluated. After spray-drying, the strain experienced over 99% loss in viability regardless of the air outlet temperature (75 and 85 °C) and the heat-adaptation temperature (45 and 65 °C, 30 min). The use of heat-adaptation treatment to improve the thermotolerance of this strain was ineffective. On the other hand, the strain showed a superior survival at 71.65%–82.07% after freeze-drying. Viable populations of 9.319–9.487 log10 cfu/g were obtained when different combinations of skim milk and sugar were used as cryoprotectant. However, the addition of sugars did not result in increased survival during the freeze-drying process. Hence, 10% (w/v) skim milk alone is recommended as a suitable protectant and drying medium for this strain. The residual moisture content obtained was 4.41% ± 0.44%.

scholarly journals Evaluation of freeze-drying conditions on the process kinetics and physicochemical properties of purple shallot

Food Research ◽  
2020 ◽  
Vol 4 (5) ◽  
pp. 1630-1636
Author(s):  
N.M. Thuy ◽  
N.T.M. Tuyen ◽  
N.V. Thanh ◽  
N.V. Tai
Keyword(s):  
Moisture Content ◽  
Freeze Drying ◽  
Chemical Properties ◽  
Sample Pretreatment ◽  
Freezing Temperature ◽  
Moisture Diffusivity ◽  
Freezing Time ◽  
Freeze Dried ◽  
Thin Layer Drying ◽  
Drying Conditions

Purple shallot is an important vegetable crop in Vietnam and throughout the world. Its storage is difficult hence, it is dehydrated for value addition. Freeze drying is one of the options for dehydration of purple shallot. There are two main stages (freezing and drying) in the complete freeze-drying process after sample pretreatment. In this study, the sample was frozen at different temperatures and times (-20 to -60oC and 5 to 9 hrs, respectively). Controlling the selected temperature (from the second stage) and pressure 0.001 mbar, eight thin layer drying models were fitted to the experimental moisture content. The physical and chemical properties and antioxidant capacity of freeze-dried purple shallot were evaluated. The obtained results showed that the TPC values and DPPH% almost increased as the freezing time increased at the same freezing temperature. The best drying conditions were found at a freezing time of 7 hrs, freezing temperature of -60oC, a pressure of 0.001 mbar, and a lyophilization time of 12 hrs. Under these conditions, the moisture content, TPC and DPPH% of the final product were 1.56%, 16.95 mg GAE/g and 65.67%, respectively. Among the models proposed, Page's model gave a better fit for the freeze-drying condition used. In freeze-drying, effective moisture diffusivity was estimated to be 5.68×10-7 m 2 /s within the conditions studied.

scholarly journals Investigation of design space for freeze-drying injectable ibuprofen using response surface methodology

2021 ◽  
Vol 71 (1) ◽  
pp. 81-98
Author(s):  
Maja Preskar ◽  
Danijel Videc ◽  
Franc Vrečer ◽  
Mirjana Gašperlin
Keyword(s):  
Moisture Content ◽  
Statistical Model ◽  
Specific Surface ◽  
Response Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Freeze Drying ◽  
Design Space ◽  
Residual Moisture Content ◽  
Residual Moisture

AbstractThis study explores the use of a statistical model to build a design space for freeze-drying two formulations with ibuprofen. A 2 × 3 factorial experimental design was used to evaluate independent variables (filling volume and annealing time) and responses as residual moisture content, specific surface area and reconstitution time. A statistical model and response surface plots were generated to define the interactions among the selected variables. The models constructed for both formulations suggest that 1 mL of filled volume and no annealing should be used to achieve optimal residual moisture content, specific surface area and reconstitution time. The proposed models were validated with additional experiments, in which the responses observed were mainly in close agreement with the predicted ones. Additionally, the established models demonstrate the reliability of the evaluation procedure in predicting the selected responses.

Residual moisture content in semi-finished leather under roller pressing

2021 ◽  
Author(s):  
Shavkat Khurramov ◽  
Farkhad Khalturaev ◽  
Eshmurad Buriyev
Keyword(s):  
Moisture Content ◽  
Residual Moisture Content ◽  
Residual Moisture

scholarly journals Effect of drying methods on properties of green curry powder

2018 ◽  
Vol 192 ◽  
pp. 03023
Author(s):  
Natthacha Chaloeichitratham ◽  
Pornkanya Mawilai ◽  
Thadchapong Pongsuttiyakorn ◽  
Pimpen Pornchalermpong
Keyword(s):  
Moisture Content ◽  
Bulk Density ◽  
Water Activity ◽  
Freeze Drying ◽  
Total Phenolic ◽  
Drying Methods ◽  
Hot Air Drying ◽  
Air Drying ◽  
Drying Temperature ◽  
Hot Air

In this study, the effects of two drying methods: hot-air and freeze drying for Thai green curry paste in a terms of drying time and qualities have been investigated. The hot-air drying was carried out in tray dryer at temperature of 50, 60 and 70 °C. The freeze drying was carried out in freeze dryer at freezing temperature of -20°C, primary drying temperature of -10°C and secondary drying temperature of 50°C. Moisture content, water activity, colour, bulk density, and total phenolic content (TPC) were determined in samples. Freeze dried sample had significantly (p<0.05) lower moisture content, water activity, bulk density, total colour difference and browning index than hot air dried samples. For antioxidant activity, the results showed hot-air drying at 70°C effected highest TPC similar to freeze drying.

scholarly journals Environmental Durability Enhancement of Natural Fibres Using Plastination: A Feasibility Investigation on Bamboo

Molecules ◽  
2020 ◽  
Vol 25 (3) ◽  
pp. 474
Author(s):  
Daanvir K. Dhir ◽  
Armin Rashidi ◽  
Grant Bogyo ◽  
Ron Ryde ◽  
Sepideh Pakpour ◽  
...  
Keyword(s):  
Moisture Content ◽  
Moisture Absorption ◽  
Natural Fibers ◽  
Natural Fibre ◽  
Natural Fibres ◽  
Residual Moisture Content ◽  
Micro Computed Tomography ◽  
Residual Moisture ◽  
X Ray ◽  
Degradation Rates

Natural fibers are gaining wide attention due to their much lower carbon footprint and economic factors compared to synthetic fibers. The moisture affinity of these lignocellulosic fibres, however, is still one of the main challenges when using them, e.g., for outdoor applications, leading to fast degradation rates. Plastination is a technique originally used for the preservation of human and animal body organs for many years, by replacing the water and fat present in the tissues with a polymer. This article investigates the feasibility of adapting such plastination to bamboo natural fibres using the S-10 room-temperature technique in order to hinder their moisture absorption ability. The effect of plastination on the mechanical properties and residual moisture content of the bamboo natural fibre samples was evaluated. Energy dispersive x-ray spectroscopy (EDS) and X-ray micro-computed tomography (Micro-CT) were employed to characterize the chemical composition and 3-dimensional morphology of the plastinated specimens. The results clearly show that, as plastination lessens the hydrophilic tendency of the bamboo fibres, it also decreases the residual moisture content and increases the tensile strength and stiffness of the fibers.

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