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

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

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

In-line near infrared spectroscopy during freeze-drying as a tool to measure efficiency of hydrogen bond formation between protein and sugar, predictive of protein storage stability

Sugars are often used as stabilizers of protein formulations during freeze-drying. However, not all sugars are equally suitable for this purpose. Using in-line near-infrared spectroscopy during freeze-drying, it is shown here that hydrogen bond formation during freeze-drying, under secondary drying conditions in particular, can be related to the preservation of the functionality and structure of proteins during storage. The disaccharide trehalose was best capable of forming hydrogen bonds with the model protein, lactate dehydrogenase, thereby stabilizing it, followed by the molecularly flexible oligosaccharide inulin 4kDa. The molecularly rigid oligo- and polysaccharides dextran 5kDa and 70kDa, respectively, formed the least amount of hydrogen bonds and provided least stabilization of the protein. It is concluded that smaller and molecularly more flexible sugars are less affected by steric hindrance, allowing them to form more hydrogen bonds with the protein, thereby stabilizing it better

Analysis of heat and mass transfer mechanism of vacuum freeze-drying in the primary drying

The freeze-drying process is a complex heat and mass transfer process virtually. The drying process of freeze-drying is not only the key stage which decides the success of freeze-drying, but also the most difficult stage to control. There are lots of papers about heat and mass transfer in vacuum freeze drying at home and abroad. The present status of research on heat and mass transfer during vacuum freeze drying in the primary drying is summed up and analyzed, the trend of research in this field is discussed in this paper

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

Mathematical model of vacuum freeze-drying in the secondary drying

The freeze-drying process is a complex heat and mass transfer process virtually. The drying process of freeze-drying is not only the key stage which decides the success of freeze-drying, but also the most difficult stage to control. There are lots of papers about heat and mass transfer in vacuum freeze drying at home and abroad. The present status of research on heat and mass transfer during vacuum freeze drying in the secondary drying is summed up and analyzed, and the trend of research in this field is discussed in this paper

In vitro Alpha Lipoic Acid supplementation in freeze-dried human sperm: the impact on DNA fragmentation index

Freeze-drying technique is an alternative method on sperm preservation. However, this process can results in DNA damage. Adding antioxidants before freezing can reduce the detrimental effects of ROS on spermatozoa. Alpha lipoic acid (ALA) is one of the potent antioxidant that can be used to protect the sperm DNA. This study was aimed to determine the effect of ALA supplementation before freeze-drying on the DNA fragmentation index (DFI) of human spermatozoa. Nine semen samples were collected and evaluated for DFI (O1) then divided into 3 groups; freeze-drying without ALA (O2), freeze-drying with ALA 1,25 mg (O3) and freeze-drying with ALA 2,5 mg (O4).All three groups were stored at 4oC for 1 week. Sperm DFI were evaluated before and after freeze-drying. The result of this study showed a significant increase in sperm DFI in all three groups after freeze-drying (p<0,05) when compared to DFI before freeze-drying (14,67 ±3,295). However there was no significant difference between O2 (26,90 ±9,180) and O4 (29,29 ±5,524) group where the supplementation of 2,5 mg ALA did not have significant effect on protecting the DNA of freeze-dried human spermatozoa. The highest DFI was in the O3 group (44,64 ±11,717). Therefore, ALA supplementation before freeze-drying does not have a significant effect on protecting the DNA of freeze-dried human spermatozoa

Effect of different drying techniques on the drying time and energy of blueberry

Blueberries (Vaccinium corymbosum L.) were dried combining vacuum, infrared, hot-air and freeze drying technologies. In this paper, examined the drying time and energy consumption of dewatering methods. The rehydration as a physical property were evaluated in dried blueberries. Combination of vacuum dried and freeze dried blueberries had higher rehydration ratio, followed by the single freeze drying, combination of hot-air drying and freeze drying, and infrared-freeze drying methods. The performance evaluation indicated that combination drying of blueberries at twostage infrared-freeze drying with 60°C and 15 min pre-drying reduced the drying time by 53.4%, besides consuming less energy (52.9%) compared to single freeze drying. Based on the results, primarily vacuum pre-drying, infrared predrying and freeze finish-drying may be the economical and optimal solution for dehydrating blueberries

Effect of Cryoprotectant Concentration on Starter Culture Viability Sinbiotic Yogurt with Freeze Dried Sweet Potato Extract Supplementation

Synbiotic yogurt with purple sweet potato extract supplementation as prebiotics and Lactobacillus plantarum Dad 13 isolated from buttermilk as probiotics has potential as functional food, but requires low storage temperatures. The freeze drying technique requires cryoprotectant as a protective material for products such as yogurt. The purpose of this study was to determine the effect of sucrose concentration on the level of viability of  Lactic Acid Bacteria and Lactobacillus plantarum. This study used a Completely Randomized Design with one factor : concentration of sucrose as cryoprotectant: 0%, 2.5%, 5%, 7.5%, and was carried out in three replications. The results showed that the concentration of sucrose significantly affected the yield of freeze dried synbiotic yogurt, total Lactic Acid Bacteria (LAB) after freeze drying, and total Lactobacillus plantarum before and after freeze drying, but did not significantly total amount of LAB before freeze drying. The best treatment, shown in frozen dried synbiotic yogurt with a sucrose cryoprotectant concentration of 5%. The treatment has the following characteristics: yield, 14.797%, total Lactic Acid Bacteria  1.98x 109 CFU / ml before freeze drying, 9.28x 108 CFU / ml after freeze drying, total Lactobacillus plantarum 8.23 x 108 CFU / ml before freeze drying and 6.81 x 108 CFU / ml after freeze drying