Freeze-drying Conditions Research Articles

Process Parameters as Tools to Intensify the Freeze-Drying Process and Modify the Sorption Properties of the Obtained Freeze-Dried Products

This study aimed to investigate the effect of the application of different freeze-drying conditions on the process’s kinetics and the sorption properties of dried apples. Slices of apples were frozen and subjected to a freezing-drying process with different combinations of shelf temperature (−20, 10, 20, and 30 °C) and pressure (37, 63, 103, and 165 Pa). During the freeze-drying, the temperature in the centre of the material was recorded. The moisture content in the dried material and changes in the water content in dried apples stored at a humidity of 75.3% were obtained. The Midilli et al. model was used to describe the drying kinetics of the freeze-drying with a good fit. Drying time increased from 660 (variant with a constant shelf temperature of 30 °C, pressure 63 Pa) to 1305 min (variants with temperatures −20:10:20:30 °C, pressure 63 Pa). For this reason, the most favourable experimental parameters were a temperature of 30 °C and a pressure of 63 Pa. However, applying these parameters caused higher absorption of water vapour during storage. Therefore, the selection of freeze-drying parameters should also be related to the expected properties of the final product.

Cheese Whey Protein and Blueberry Juice Mixed Fermentation Enhance the Freeze-Resistance of Lactic Acid Bacteria in the Freeze-Drying Process.

The effects of MRS, whey protein and blueberry alone, and mixed fermentation on the survival rate of lactic acid bacteria under various freeze-drying conditions were investigated. The surface structure of the freeze-dried powders was also investigated to explore the anti-freezing protection mechanism of mixed whey protein and blueberry fermentation on the bacteria. It was found that the mixed fermentation medium of blueberry and whey protein has a protective effect on the freeze-drying bacteria and is better than the traditional MRS and whey protein medium. The optimal concentration of blueberry juice addition was 9%. The survival rate of the pre-freezing temperature at -80 °C was higher than at -20 °C after the pre-freezing and freeze-drying processes. The freeze-drying thickness of 0.3 cm could improve the survival rate of the bacteria. The Fourier transform infrared spectroscopy results indicated the interaction between the whey protein, anthocyanins, and the surface composition of the lactic acid bacteria.

S-layer proteins in microencapsulated freeze-dried probiotic Levilactobacillus brevis strains

The presence of surface (S)-layer proteins as a rare property of lactic acid bacteria plays an important role in the expression of the probiotic properties of the producer strain and protects the cells from unfavourable environmental conditions. Therefore, the aim of this work was to evaluate the role of S-layer proteins of four Levilactobacillus brevis MB1, MB2, MB13, and MB20 strains, previously isolated from human milk. The results showed better survival under simulated gastrointestinal tract (GIT) conditions and better adhesion to Caco-2 cells, achieved when S-proteins were present on the surface of the examined probiotic Levilactobacillus brevis strains. Free cells and cells microencapsulated in alginate, with or without galactooligosaccharides (GOS) and fructooligosaccharides (FOS), survived in high numbers during freeze-drying and one-month storage at 4 °C, as well as during exposure to simulated GIT conditions (>108 CFU/g), thus fulfilling the primary technological criterion for the selection of probiotic strains. Higher survival of freeze-drying of encapsulated cells than free cells, can be attributed to the protective effect of alginate, GOS and FOS as prebiotic agents. However, GOS was more protective than FOS in maintaining the viability of microencapsulated Levilactobacillus brevis MB1, MB2, MB13 and MB20 cells in alginate during storage and under the harsh conditions of GIT and freeze-drying.

Characterization of Porous β-Type Tricalcium Phosphate Ceramics Formed via Physical Foaming with Freeze-Drying.

Porous β-tricalcium phosphate (Ca3(PO4)2; β-TCP) was prepared via freeze-drying and the effects of this process on pore shapes and sizes were investigated. Various samples were prepared by freezing β-TCP slurries above a liquid nitrogen surface at -180 °C with subsequent immersion in liquid nitrogen at -196 °C. These materials were then dried under reduced pressure in a freeze-dryer, after which they were sintered with heating. Compared with conventional heat-based drying, the resulting pores were more spherical, which increased both the mechanical strength and porosity of the β-TCP. These materials had a wide range of pore sizes from 50 to 200 µm, with the mean and median values both approximately 100 µm regardless of the freeze-drying conditions. Mercury porosimetry data showed that the samples contained small, interconnected pores with sizes of 1.24 ± 0.25 µm and macroscopic, interconnected pores of 25.8 ± 4.7 µm in size. The effects of nonionic surfactants having different hydrophilic/lipophilic balance (HLB) values on foaming and pore size were also investigated. Materials made with surfactants having lower HLB values exhibited smaller pores and lower porosity, whereas higher HLB surfactants gave higher porosity and slightly larger macropores. Even so, the pore diameter could not be readily controlled solely by adjusting the HLB value. The findings of this work indicated that high porosity (>75%) and good compressive strength (>2 MPa) can both be obtained in the same porous material and that foaming agents with HLB values between 12.0 and 13.5 were optimal.

The influence of drying and storage conditions on the volatilome and cannabinoid content of Cannabis sativa L. inflorescences

The increasing interest in hemp and cannabis poses new questions about the influence of drying and storage conditions on the overall aroma and cannabinoids profile of these products. Cannabis inflorescences are subjected to drying shortly after harvest and then to storage in different containers. These steps may cause a process of rapid deterioration with consequent changes in precious secondary metabolite content, negatively impacting on the product quality and potency. In this context, in this work, the investigation of the effects of freeze vs tray drying and three storage conditions on the preservation of cannabis compounds has been performed. A multi-trait approach, combining both solid-phase microextraction (SPME) two-dimensional gas chromatography coupled to mass spectrometry (SPME-GC × GC–MS) and high-performance liquid chromatography (HPLC), is presented for the first time. This approach has permitted to obtain the detailed characterisation of the whole cannabis matrix in terms of volatile compounds and cannabinoids. Moreover, multivariate statistical analyses were performed on the obtained data, helping to show that freeze drying conditions is useful to preserve cannabinoid content, preventing decarboxylation of acid cannabinoids, but leads to a loss of volatile compounds which are responsible for the cannabis aroma. Furthermore, among storage conditions, storage in glass bottle seems more beneficial for the retention of the initial VOC profile compared to open to air dry tray and closed high-density polyethylene box. However, the glass bottle storage condition causes formation of neutral cannabinoids at the expenses of the highly priced acid forms. This work will contribute to help define optimal storage conditions useful to produce highly valuable and high-quality products.Graphical

Effect of TiO2 Drying Conditions on the Catalytic Activity of Pt for Ammonia Synthesis from NO−H2

AbstractThe effect of drying conditions on the physicochemical and catalytic properties of TiO2 were examined for NO to ammonia reaction. TiO2 prepared by different drying conditions such as evaporation (EP), evaporation under reduced pressure (ER) and evaporation under freeze drying conditions (EF) was used for support for Pt loading. At low temperature (below 175 °C), the order for ammonia formation was Pt/TiO2(ER)>Pt/TiO2(EP)>Pt/TiO2(EF). Notably, Pt/TiO2(ER) catalyst was more effective than Pt/TiO2 prepared from commercially available TiO2. The characterization of these catalysts revealed that rutile‐rich phase TiO2, high Pt dispersion and moderate acidic sites were influential factors for ammonia formation. TiO2 drying conditions modified surface properties of TiO2 and consequently, catalytic activity for ammonia formation.

Essential oil production, chemical composition, bioactive compounds, and antioxidant activity of Thymus vulgaris as affected by harvesting season and drying conditions

In this study, the effects of seven distinct were assessed in two harvesting seasons (spring and autumn) on the essential oil (EO) content, total phenolic content (TPC), total flavonoid content (TFC), antioxidant activity, and volatile compounds of thyme (Thymus vulgaris L.). The drying methods tested included sun-drying, shade-drying, freeze-drying (FD), oven drying at 40 °C (OV40) and 70 °C (OV70), and microwave 360 W (MW360) and 720 W (MW720). The analysis of essential oils facilitated the identification of numerous compounds, 18 of which accounted for approximately 64.94% to 67.84% of the total thyme EO compounds. Six significant compounds were investigated, including thymol, p-cymene, γ-terpinene, carvacrol, linalool, and borneol. The results demonstrated that the thyme samples harvested in spring possessed higher amounts of γ-terpinene, thymol, carvacrol, EO content, and TFC, while samples harvested in autumn exhibited the highest amounts of borneol, p-cymene, TPC, and higher antioxidant activity. Principal component analysis (PCA) findings revealed that thyme samples harvested in spring, dried in the sun, shade, and FD conditions were rich in EO content, γ-terpinene. The samples dried in MW720, OV40, and FD conditions possessed the highest amounts of thymol, carvacrol, and TFC. Drying the samples under MW360, OV40, and FD indicated significantly higher TPC and linalool. Drying the autumn-harvested samples under the sun and shade also exhibited higher linalool and TFC than other methods. Overall, the results conclusively indicated that the harvesting season and drying conditions significantly affected bioactive compounds, antioxidant activity, and EO production and quality. Such findings may add value to the product at the producers’ levels to produce more quality thyme depending on the harvesting season.

Simulation of ice deposition in a freeze dryer condenser: A computational fluid dynamics study

The development and validation of a mechanistic model for the deposition of ice within a freeze-dryer condenser using Computational Fluid Dynamics is presented in this paper. Freeze-drying, a dehydration technique used widely in the pharmaceutical and food industries, involves the sublimation of frozen product moisture under controlled conditions. The efficiency of the condenser has a significant impact on the overall process efficiency and product quality. Therefore, a comprehensive understanding of ice deposition is essential for freeze-drying processes. The proposed condensation model integrates fundamental heat and mass transfer principles with the specific interactions that occur at the solid-vapour interface during ice deposition, and integrates it further with transport phenomena in the condenser, including fluid flow, heat and vapour transport influencing the deposition kinetics of the ice. To validate the model, experiments were conducted under controlled freeze-drying conditions, and the results compared with the results of the developed model. The numerical results fell within the confidence interval of the measured values, which shows a high degree of agreement between the model predictions and the experimental data, and confirms the reliability of the proposed approach. Using the validated model, a parametric study was also conducted, to evaluate the effects of condenser temperature, sublimation rate and the presence of inert gas on the pressures within the system and the efficiency of the deposition. The mechanistic model provides detailed insights into the ice deposition kinetics during freeze drying, and enables process engineers to optimise the condenser design and operating parameters in order to improve performance and product quality.

Optimizing the viability of microencapsulated Lactiplantibacillus plantarum using response surface methodology for dietary probiotic delivery

The study aimed to develop a microencapsulated probiotic (Lactiplantibacillus plantarum) delivery method, cryoprotected by chitosan-inulin complex microcapsules and freeze-dried to obtain maximum cell viability. Probiotic viability was assessed using simulated gastrointestinal conditions and storage at different temperatures. The L. plantarum microcapsules were developed using a Box-Behnken experimental design with varied concentrations of CaCl2, chitosan, and Inulin as an encapsulant agents. In addition, the current study used the response surface approach to explore the influence of various formulations and storage capsulate viabilities to verify an optimized L plantarum formulation. Under optimum conditions, small microbeads with the highest cell encapsulation efficiency were produced and the highest cell viability (68.33 %) was obtained. The results showed that the intelligent microcapsule of L. plantarum with SM significantly increased the viability of cells (p < 0.05) (approx. 108 log CFU/mL) and the release of the extract (85 %) in gastric simulation and intestinal simulation fluids, respectively when compared with free bacteria. In general, microencapsulated L. plantarum under previously optimized freeze-drying conditions showed promising efficiency that depends on cell viability during drying, gastrointestinal treatment, and refrigerated storage conditions and on the physicochemical properties of the powders.

Optimization of extraction and lyophilization conditions of Feretia apodanthera (Rubiaceae) leaf powders for galenic formulation

Feretia apodanthera (Rubiaceae) is used in traditional medicine for the treatment of various pathologies. Its leaves are chewed and swallowed to treat stomach aches, sleep disorders, etc. With the aim of improving the extraction method in order to obtain high contents of phytochemical compounds and good antioxidant activity, this study aimed to highlight the extraction and lyophilization conditions of two extracts (aqueous and hydro-ethanolic) leaves of Feretia apodanthera.&#x0D; An aqueous and hydro-ethanolic extraction was carried out from the leaf powder of Feretia apodanthera, after a maceration plan (mass/volume ratio and extraction time). The extracts obtained were freeze-dried (flask size, filling volume and freeze-drying time) in order to determine the optimal extraction conditions. A phytochemical screening of the extracts with extreme yields of different solvents was carried out by TLC, which led to the determination of certains compounds of interest and the evaluation of the antioxidant activity by the DPPH and FRAP method.&#x0D; The optimal maceration conditions were 02 hours and m/V ratio of 1/20 for the aqueous extract and those of the ethanolic extract were 30 min and m/V ratio of 1/20. The optimal freeze-drying conditions were 60h and a 500ml flask 1/3 filled. The presence of flavonoids, tannins, saponosides, coumarins, triterpenes and sterols has been highlighted. The phenolics compounds contents of hydro-ethanolic lyophilisates were higher than those of aqueous lyophilisates. There was no statistical difference between the antioxidant activity of the different extracts.&#x0D; The optimal conditions will serve as a standard for the production of the extract necessary for the formulation.&#x0D; Keywords : Feretia apodanthera, extraction, freeze-drying, phenolics compounds, antioxidant.

Multivalent nanobody engineering for enhanced physisorption and functional display on gold nanoparticles.

The ease of expression and engineering of single domain antibodies, known as nanobodies, make them attractive alternatives to conventional antibodies in point-of-care diagnostics such as lateral flow assays. In lateral flow assays, gold nanoparticle bioconjugates serve as labels which display affinity molecules on the gold surface. While examples of nanobody gold nanoparticle bioconjugates exist, few utilise the simple one-step approach of physisorption owing to undesirable nanoparticle aggregation and loss of functionality. Here we show that engineering nanobodies into multivalent structures can significantly enhance their functionality when physisorbed onto gold nanoparticles. This approach enables resulting bioconjugates to withstand multiple processing steps required for long-term nanoparticle storage within lateral flow assays. Specifically, we show that the trivalent version of VHHV nanobody (VHH3) against the S1 protein of SARS-CoV-2 can be immobilised onto gold nanoparticles through passive adsorption. Unlike its monovalent and bivalent nanobody counterparts, using VHHV3 preserves nanoparticle stability under salt stress, blocking, washing, and freeze-drying conditions while maintaining picomolar sensitivity to the S1 protein. We anticipate that this facile strategy is a significant advancement towards the integration of nanobodies in lateral flow assay development.

Practical Advice on Scientific Design of Freeze-Drying Process: 2023 Update

ObjectiveThe purpose of this paper is to re-visit the design of three steps in the freeze-drying process, namely freezing, primary drying, and secondary drying steps. Specifically, up-to-date recommendations for selecting freeze-drying conditions are provided based on the physical–chemical properties of formulations and engineering considerations.Methods and ResultsThis paper discusses the fundamental factors to consider when selecting freezing, primary drying, and secondary drying conditions, and offers mathematical models for predicting the duration of each segment and product temperature during primary drying. Three simple heat/mass transfer primary drying (PD) models were tested, and their ability to predict product temperature and sublimation time showed good agreement. The PD models were validated based on the experimental data and utilized to tabulate the primary drying conditions for common pharmaceutical formulations, including amorphous and partially crystalline products. Examples of calculated drying cycles, including all steps, for typical amorphous and crystalline formulations are provided.ConclusionsThe authors revisited advice from a seminal paper by Tang and Pikal (Pharm Res. 21(2):191-200, 2004) on selecting freeze-drying process conditions and found that the majority of recommendations are still applicable today. There have been a number of advancements, including methods to promote ice nucleation and computer modeling for all steps of freeze-drying process. The authors created a database for primary drying and provided examples of complete freeze-drying cycles design. The paper may supplement the knowledge of scientists and formulators and serve as a user-friendly tool for quickly estimating the design space.

Fabrication and Characterization of Freeze-Cast Tubular Solid Oxide Cells

Increasing triple phase boundaries (TPBs) and reducing gas diffusion limitation in electrodes of solid oxide fuel cells (SOFCs) and solid oxide electrolysis cells (SOECs) have always been a goal for highly desirable electrochemical performance. Freeze-casting (also called ice-templating) is a promising method to produce hierarchically arranged porous ceramics with aligned and directional pores that could assist to reach such a goal. After reviewing the previous work on ceramic freeze casting, we focused on optimizing the processes to better engineer tubular supports for SOFC as well as SOEC applications. Although the optimized process does not have too many constraints on the types of ceramic materials (except particle size and surface area), we selected the commonly used 8 mol.% yttria stabilized zirconia (8YSZ)/NiO composite material set as a starting point. Cast slurry formulations, cast temperatures, slurry feeding methods and freeze-drying conditions were studied. Microstructures of the tubular parts prepared at various conditions were examined. Finally, as an example for SOFC application, the fuel cell performance was reported. Figure 1

Probiotic Lactic Acid Bacteria for Vaginal Application. Optimization of Biomass Production and Freeze-Drying Conditions

Probiotic formula for the vaginal tract must contain high numbers of viable beneficial bacteria that maintain their characteristics during the production and further storage, in order to exert the claimed probiotic effect. Four probiotic strains—Lactobacillus gasseri CRL1320, Limosilactobacillus reuteri CRL1324, Ligilactobacillus salivarius CRL1328 and Lacticaseibacillus rhamnosus CRL1332—originally isolated from vagina of healthy women exhibiting beneficial properties were evaluated. Therefore, the optimization of growth parameters and dry biomass production with high viability while preserving probiotic features of strains is a great challenge. Different growth conditions in MRS medium were set up in a laboratory bioreactor; two initial pH and agitation were recorded speeds during static or controlled fermentations. Production conditions of 37 °C with controlled pH 6.5 and 5.5-MRS with 150 and 75 rpm stirring speeds were used for CRL1329 and CRL1332 strains, respectively, while static and free pH MRS for CRL1324 and CRL1328 probiotics allowed us to obtain maximal cell viability counts. However, during 12 h of fermentation, biomass yields of 19.3, 16.2 and 15.2 g/L were achieved when CRL1329, CRL1328 and CRL1324 probiotic strains were grown in static and free pH MRS. The highest biomass yield for CRL1332 strain was produced under controlled MRS-initial pH 6.5 and 75 rpm fermentation conditions. To preserve probiotic high biomass viability, freeze-drying was carried out in the presence of different cryoprotective agents. Thus, the highest viable numbers (10.9–11.8 log CFU/g) with survival rates between 91.3 and 95.6% were attained in the presence of 10% trehalose (L. reuteri and L. salivarius), lactose (L. rhammosus) and lactose + trehalose + sucrose mix (L. gasseri). When stability during post-freeze-drying storage was evaluated, probiotic strains showed a remarkably higher viability recovery when stored at 4 °C than at 25 °C for 12 and 3 months, respectively. In addition, surface characteristics of vaginal probiotics were affected to different extents during storage depending on the strain, protective agent and storage time/temperature. Critical factors for growth conditions, drying process and storage stability of probiotic lactobacilli strains were optimized in view to preserve cell high viability and surface features for the design of vaginal probiotic formula.

Fabrication and Characterization of Freeze-Cast Tubular Solid Oxide Cells

Increasing triple phase boundaries (TPBs) and reducing gas diffusion limitation in electrodes of solid oxide fuel cells (SOFCs) and solid oxide electrolysis cells (SOECs) have always been a goal for highly desirable electrochemical performance. Freeze-casting (also called ice-templating) is a promising method to produce hierarchically arranged porous ceramics with aligned and directional pores that could assist to reach such a goal. After reviewing the previous work on ceramic freeze-casting, we focused on optimizing the processes to better engineer tubular supports for SOFC as well as SOEC applications. Although the optimized process does not have too many constraints on the types of ceramic materials (except particle size and surface area), we selected the commonly used 8 mol.% yttria stabilized zirconia (8YSZ)/NiO composite material set as a starting point. Cast slurry formulations, cast temperatures, slurry feeding methods and freeze-drying conditions were studied. Microstructures of the tubular parts prepared at various conditions were examined. Finally, as an example for SOFC application, the fuel cell performance is reported.

Highly Stable Docetaxel-Loaded Nanoparticles Based on Poly(D,L-lactide)-b-Poly(ethylene glycol) for Cancer Treatment: Preparation, Characterization, and In Vitro Cytotoxicity Studies.

Stability and narrow size distribution are among the main requirements that apply to drug formulations based on polymeric nanoparticles. In this study, we obtained a series of particles based on biodegradable poly(D,L-lactide)-b-poly(ethylene glycol) (P(D,L)LAn-b-PEG113) copolymers with varied hydrophobic P(D,L)LA block length n from 50 to 1230 monomer units stabilized by poly(vinyl alcohol) (PVA) by a simple "oil-in-water" emulsion method. We found that nanoparticles of P(D,L)LAn-b-PEG113 copolymers with relatively short P(D,L)LA block (n ≤ 180) are prone to aggregate in water. P(D,L)LAn-b-PEG113 copolymers with n ≥ 680 can form spherical unimodal particles with values of hydrodynamic diameter less than 250 nm and polydispersity less than 0.2. The aggregation behavior of P(D,L)LAn-b-PEG113 particles was elucidated in terms of tethering density and conformation of PEG chains at the P(D,L)LA core. Docetaxel (DTX) loaded nanoparticles based on P(D,L)LA680-b-PEG113 and P(D,L)LA1230-b-PEG113 copolymers were formulated and studied. It was observed that DTX-loaded P(D,L)LAn-b-PEG113 (n = 680, 1230) particles are characterized by high thermodynamic and kinetic stability in aqueous medium. The cumulative release of DTX from the P(D,L)LAn-b-PEG113 (n = 680, 1230) particles is sustained. An increase in P(D,L)LA block length results in a decrease in DTX release rate. The in vitro antiproliferative activity and selectivity studies revealed that DTX-loaded P(D,L)LA1230-b-PEG113 nanoparticles demonstrate better anticancer performance than free DTX. Favorable freeze-drying conditions for DTX nanoformulation based on P(D,L)LA1230-b-PEG113 particles were also established.

Effects of lyoprotectant and encapsulated Lactobacillus acidophilus KBL409 on freeze-drying and storage stability

The purpose of this study was to optimize the encapsulated formulation and freeze-drying conditions of Lactobacillus acidophilus KBL409 to improve shelf-life. The optimum freeze-drying conditions was 8% sucrose as a lyoprotectant at −30 °C. In addition, the free, alginate-encapsulated (Al-), and alginate/chitosan-encapsulated (Al/Chi-) L. acidophilus KBL409 with or without sucrose were prepared and evaluated for the simulated gastrointestinal (SGI) tract, moisture characteristics, and storage stability. The freeze-dried Al/Chi-cells with sucrose displayed the highest survival rate of 0.14% in the SGI tract (p < 0.05). The cells showed sigmoidal sorption isotherms and moisture content of 0.084 kg water/kg solid for Brunauer-Emmett-Teller-monolayer. At 4 °C/60% RH, the glass transition temperature was 12.55 °C, which allowed for 12-week period of glassy state and the highest storage viability of 22.35%. In conclusion, the viability of Lactobacillus acidophilus KBL409 faces distinct challenges for freeze-drying and storage, and encapsulation with lyoprotectant affects various stability and quality attributes of microorganisms.

Drying Methods Affect the Drying Kinetics, Bioactive Characteristics and Essential Oil Composition of Lavender (Lavandula angustifolia Mill.) and Lavandin (Lavandula hybrida)

This study aimed effects of drying methods on drying kinetics, effective moisture diffusivity, color properties, total phenolic content, antiradical activity and essential oil composition of some selected lavender and lavandin genotypes. Six different genotypes developed by selection breeding at Erciyes University between 2017-2020 were used as plant materials grown under open-field conditions. Six different drying methods (convective, open-shade, open-sun, greenhouse, hybrid and freeze) were performed and compared. Statistical values showed that drying was best described by Wang & Singh mathematical model. Greenhouse drying was the fastest method in terms of drying duration. Freeze drying had relatively good color properties for lavender and lavandin flowers. The greatest effective moisture diffusivity values were obtained in hybrid drying and the lowest in greenhouse drying. The mean values of total phenolic content and antiradical activity of convective drying were statistically lower than from other drying methods. The highest essential oil ratios obtained in following drying methods with decreasing order: convective (5.10%), open-shade (4.65%), freeze (4.53%), open-sun (4.49%), greenhouse (4.33%) and hybrid (2.22%). The linalool ratio ranged between 27.16 to 79.21% and the highest value was obtained in the freeze-drying condition of the G208 genotype. In conclusion, open-shade drying method significantly positively affects bioactive characteristics and essential oil composition.

Influence of Pretreatments and Freeze-Drying Conditions of Strawberries on Drying Kinetics and Physicochemical Properties

The aim of this study is to analyze the effects of pretreatments and drying temperature on the freeze-drying (FD) kinetics, ascorbic acid content, color changes, and antioxidant activity (AA) of strawberries. Experiments were performed at 20 °C, 40 °C, and 60 °C, with a constant pressure of 63 Pa in the FD chamber. The strawberry samples were cut into slices (CS) and pulped (PS) before drying. The drying kinetics was best described using the Midilli or logistic model depending on the strawberry grinding method used and the FD temperature. The FD of strawberries significantly increased the lightness, redness, and yellowness of the dried fruit. The FD temperature and pretreatment methods had little influence on the total phenolic content (TPC) and AA. The lowest TPC was found in strawberry pulps after dehydration at 60 °C, and the highest TPC was observed in strawberry slices dehydrated at the same temperature (18.54 and 22.04 mg of gallic acid equivalent per gram of dry mass, respectively). Furthermore, the ascorbic acid content in dried strawberries was higher for the samples freeze-dried at a higher temperature.

Exploring Properties of Edible Hydrolyzed Collagen for 3D Food Printing of Scaffold for Biomanufacturing Cultivated Meat

Cultivated meat is being explored as one of the sustainable solutions, complementing traditional meat manufacturing to meet global demand. This paper presents the novel results of a 3D food printing process for scaffolds produced from edible hydrolyzed collagen intended for biomanufacturing cultivated meat. The hydrolyzed collagen ink is designed with combinatorial chemistries and post-printing freeze-dried to create scaffold constructs. Rheological properties of the ink for 3D food printing are studied. Variation in average pore size and pore morphology of the scaffold caused by changing collagen ink composition and freeze-drying conditions is analyzed. This novel study focuses on using commercially available food-grade ingredients for cultivated meat scaffolds. Results of this study are applied to explore the viability of edible hydrolyzed collagen scaffold biomanufacturing with appropriate pore morphology using 3D food printing and freeze-drying technique.