Modelling the primary drying step for the determination of the optimal dynamic heating pad temperature in a continuous pharmaceutical freeze-drying process for unit doses

In the pharmaceutical industry, traditional freeze-drying of unit doses is a batch-wise process associated with many disadvantages. To overcome these disadvantages and to guarantee a uniform product quality and high process efficiency, a continuous freeze-drying process is developed and evaluated. The main differences between the proposed continuous freeze-drying process and traditional freeze-drying can be found firstly in the freezing step during which the vials are rotated around their longitudinal axis (spin freezing), and secondly in the drying step during which the energy for sublimation and desorption is provided through the vial wall by conduction via an electrical heating pad. To obtain a more efficient drying process, the energy transfer has to be optimised without exceeding the product and process limits (e.g. cake collapse, choked flow). Therefore, a mechanistic model describing primary drying during continuous lyophilisation of unit doses based on conduction via heating pads was developed allowing the prediction of the optimal dynamic power input and temperature output of the electric heating pads. The model was verified by experimentally testing the optimal dynamic primary drying conditions calculated for a model formulation. The primary drying endpoint of the model formulation was determined via in-line NIR spectroscopy. This endpoint was then compared with the predicted model based endpoint. The mean ratio between the experimental and model based predicted drying time for six verification runs was 1.05 +/- 0.07, indicating a good accordance between the model and the experimental data

The Effects of Freeze-Drying on the Strength Characteristics of Naturally Aged Book Papers

Libraries occasionally have water main breaks, fires and floods. These disasters cause considerable water damage to thousands of books. Books that are left wet on the shelves will grow mold. Books that are quickly frozen and eventually freeze-dried can be restored to the shelf in good condition. Several libraries have used freeze-drying for this purpose and have had great success. Freeze-drying is a process used to remove frozen liquid from a substance. The moist material is frozen and put in a vacuum. A high vacuum with some heat introduced will cause the frozen liquid to sublime. A dry-porous structure is left behind. There has been no test data found considering the effects of freeze-drying on the strength of papers. The purpose of this report is to examine this process. Eleven books up to 173 years old were wetted and freeze-dried. Some cockling of papers were observed. Strength properties of fold, tensile and zero span tensile essentially remained unchanged. Freeze-drying, in respect to the relatively small number of samples tested, does not have any detrimental effect on the strength of paper. Freeze-drying is recommended for restoration of water damaged books

The impact of freeze-drying infant fecal samples on measures of their bacterial community profiles and milk-derived oligosaccharide content.

Infant fecal samples are commonly studied to investigate the impacts of breastfeeding on the development of the microbiota and subsequent health effects. Comparisons of infants living in different geographic regions and environmental contexts are needed to aid our understanding of evolutionarily-selected milk adaptations. However, the preservation of fecal samples from individuals in remote locales until they can be processed can be a challenge. Freeze-drying (lyophilization) offers a cost-effective way to preserve some biological samples for transport and analysis at a later date. Currently, it is unknown what, if any, biases are introduced into various analyses by the freeze-drying process. Here, we investigated how freeze-drying affected analysis of two relevant and intertwined aspects of infant fecal samples, marker gene amplicon sequencing of the bacterial community and the fecal oligosaccharide profile (undigested human milk oligosaccharides). No differences were discovered between the fecal oligosaccharide profiles of wet and freeze-dried samples. The marker gene sequencing data showed an increase in proportional representation of Bacteriodes and a decrease in detection of bifidobacteria and members of class Bacilli after freeze-drying. This sample treatment bias may possibly be related to the cell morphology of these different taxa (Gram status). However, these effects did not overwhelm the natural variation among individuals, as the community data still strongly grouped by subject and not by freeze-drying status. We also found that compensating for sample concentration during freeze-drying, while not necessary, was also not detrimental. Freeze-drying may therefore be an acceptable method of sample preservation and mass reduction for some studies of microbial ecology and milk glycan analysis

Preservation of flavor in freeze dried green beans

Before freeze drying, green beans are heated to point at which their cell structure is altered. Beans freeze dried with altered cell structure have improved rehydration properties and retain color, flavor, and texture

Encapsulation of citrus by-product extracts by spray-drying and freeze-drying using combinations of maltodextrin with soybean protein and ι-carrageenan

The effect of different combinations of maltodextrin (MD) coating agents (MD, MD + soybean protein, and MD + ι-carrageenan) on the encapsulation of lemon by-product aqueous extracts using freeze-drying and spray-drying were investigated. The total phenolic content (TPC), total flavonoid content (TFC), and ferric ion reducing antioxidant power (FRAP) of the microparticles were evaluated. Freeze-drying with the mixture of MD + soybean protein resulted in the highest retention of TPC, TFC, and FRAP (1.66 ± 0.02 mg GAE/g d.b., 0.43 ± 0.02 mg CE/g d.b., and 3.70 ± 0.05 mM TE/g, respectively). Freeze-drying resulted in microparticles with lower moisture content (MC) and water activity (aw) than those produced by spray-drying. Specifically, the MC and aw of the microparticles produced by freeze-drying ranged from 1.15 to 2.15% and 0.13 to 0.14, respectively, while the MC and aw of the microparticles produced by spray-drying ranged from 6.06% to 6.60% and 0.33 to 0.40, respectively. Scanning electron microscopy revealed that spray-drying resulted in the formation of spherical particles of different sizes regardless of the type of coating agent. Although freeze-drying resulted in microparticles with amorphous glassy shapes, the mixture of MD + soybean protein resulted in the formation of spherical porous particles. X-ray diffraction revealed a low degree of crystallinity for the samples produced by both techniques.</p

Pretreatment of citrus by-products affects polyphenol recovery:a review

A large amount of citrus waste is generated annually. This waste is of great economic worth, since it contains high levels of polyphenols, which have attracted scientific interest due to their potent antimicrobial and antiradical activities. Pretreatment is a crucial step that precedes the extraction process and influences the yields and quality of polyphenols. This review emphasizes the effect of different drying processes, such as freeze drying, hot-air drying, vacuum drying, microwave drying, infrared drying, and high-speed drying, on the polyphenol retention in citrus by-products. Further treatments of the dried citrus by-products for assisting the liberation of bound polyphenols are also provided and comprehensively discussed

The meaning of some common terms used in sampling toxic phytoplankton

The author explains some aspects of sampling phytoplankton blooms and the evaluation of results obtained from different methods. Qualitative and quantitative sampling is covered as well as filtration, freeze-drying and toxin separation

Freeze-drying modeling and monitoring using a new neuro-evolutive technique

This paper is focused on the design of a black-box model for the process of freeze-drying of pharmaceuticals. A new methodology based on a self-adaptive differential evolution scheme is combined with a back-propagation algorithm, as local search method, for the simultaneous structural and parametric optimization of the model represented by a neural network. Using the model of the freeze-drying process, both the temperature and the residual ice content in the product vs. time can be determine off-line, given the values of the operating conditions (the temperature of the heating shelf and the pressure in the drying chamber). This makes possible to understand if the maximum temperature allowed by the product is trespassed and when the sublimation drying is complete, thus providing a valuable tool for recipe design and optimization. Besides, the black box model can be applied to monitor the freeze-drying process: in this case, the measurement of product temperature is used as input variable of the neural network in order to provide in-line estimation of the state of the product (temperature and residual amount of ice). Various examples are presented and discussed, thus pointing out the strength of the too

Effects of drying on pumpkin and green peper colour.

The present work evaluates the effect of different drying treatments on the colour of green bell peppers and pumpkin, which were dried using two different methods: air drying and freeze-drying. The treatments in air drying were carried out at 30 ºC and 70 ºC. Overall, it was possible to conclude that air drying at 30 ºC produces small changes in colour of green pepper whereas air drying at 70 ºC and freeze drying originate more intense colour changes. The increase of temperature on air drying augments the colour saturation of dried pumpkin while decreases the hue angle by a linear relationship. In addition, the chroma of dried pumpkin decreases significantly with the freeze drying, while the hue angle is maintained constant as compared with the fresh vegetable

Human Sperm Preservation Using Freeze-drying an Experimental Laboratory Study

Latar Belakang: Terdapat beberapa teknik preservasi sperma yang masing-masing memiliki kelebihan dan kekurangan. Salah satu alternatif tekniknya adalah dengan teknik pengeringan. Teknik ini bersifat lebih murah, mudah, dan praktis. Teknik freeze-drying masih merupakan studi empiris yang harus dibuktikan kebenarannya. Tujuan: Penelitian ini bertujuan mengevaluasi kemungkinan aplikasi tekhnik freeze-drying untuk preservasi sperma manusia dan menentukan pengaruh proses yang diikuti penyimpanan selama 7 hari pada suhu 4°C terhadap integritas DNA spermatozoa. Metoda: Pada penelitian ini digunakan Posttest Only Control Group Design. Populasi adalah sperma pria dewasa berusia 21-40 tahun dengan criteria normozoospermia menurut standard analisis semen WHO. Besar sampel adalah 12, diperoleh dengan cara simple random sampling. Integritas DNA spermatozoa dari sampel semen segar, segera setelah freeze-drying dan yang disimpan selama 7 hari pada suhu 4°C, diuji dengan Comet assay. Hipotesis diuji dengan Manova. Hasil: Integritas DNA spermatozoa kelompok sperma yang diberi perlakuan freeze-drying diikuti penyimpanan selama 7 hari pada suhu 4°C secara signifikan lebih rendah dibandingkan dengan kelompok sperma segar atau yang hanya diberi perlakuan freeze-drying (p&lt;0,01). Kesimpulan: Tidak ada perbedaan integritas DNA spermatozoa yang signifikan antara kelompok sperma segar dengan sperma yang diberi perlakuan freeze-drying (p&gt;0,05)