Residual Moisture Content Research Articles

In-line monitoring of the residual moisture in impregnated black textile fabrics by hyperspectral imaging

The residual moisture content of black textiles finished with functional agents by impregnation was monitored after drying by near-infrared (NIR) hyperspectral imaging. Quantitative moisture data are inevitably required for optimum control of the drying process of wide textile webs during converting. Since spectral imaging is carried out in reflection, the very low signal intensities resulting from both the low reflectance of black materials and the usually rough surface structure of textiles leading to scattering of the incident probe light make exceedingly high demands on both the measurement instrumentation and the multivariate regression methods used for quantification of the spectral data. The black color was found to have a strong effect on the reflectance spectra, which became manifest in a marked background. Nevertheless, the best prediction performance was obtained for calibration models based on spectra without removal of the background. External validation of the models with independent samples yielded a root mean square error of prediction (RMSEP) of 0.55 wt%. Surprisingly, this prediction error is completely in line with the corresponding errors obtained previously for comparable bright textiles in spite of the much more challenging optical conditions for the black materials. Using the developed calibration models, hyperspectral monitoring of finished black blended fabrics with both homogeneous and nonhomogeneous moisture distribution was carried out. It was shown that both local and large-range fluctuations can be easily detected by spectral imaging, which makes this method very useful for the control of technical textile production and converting processes.

A machine learning approach in drying of microalga Chlorella minutissima in a single rotary drum dryer for biodiesel production

Drying of Chlorella minutissima slurry was carried out in a single rotary drum dryer at varied drum surface temperature and rotational speed to achieve higher lipid yield for biodiesel conversion. Residual moisture content and lipid yield of the corresponding drum speed and drum surface temperature were mapped. Application of the machine learning tool classified the range of residual moisture content to be <10% (wet biomass) for high lipid recovery with an accuracy of 97%. Based on the drying time, lipid recovery, and energy consumption, drying at 80°C drum surface temperature with 0.3 rpm resulted ˃90% lipid recovery as compared to the bone-dried biomass. The energy consumption of 7.328 kWh for 1 kg of dried biomass was recorded with profound reduction in drying time as compared to oven and tray drying of algal slurry. The fatty acid methyl ester profile of C. minutissima biodiesel constituted higher proportion of saturated fatty acids followed by monounsaturated fatty acid and polyunsaturated fatty acids. Various fuel characteristics, namely, viscosity, density, free glycerin, triglycerides, diglycerides, monoglycerides, copper strip corrosion, flash point, cetane index, iodine value, calorific value, acid value, saponification value, phosphorous, sulfur, water, and ash contents were analyzed, and showed values within the specified limits of national and international biodiesel standards. Thus, considering the drying time, energy consumption, and lipid recovery with suitable fuel properties, the drum dryer could be recommended for drying the microalgal slurry for large-scale operation.

A Design of Experiment Approach to Optimize Spray-Dried Powders Containing Pseudomonas aeruginosaPodoviridae and Myoviridae Bacteriophages.

In the present study, we evaluated the effect of spray-drying formulations and operating parameters of a laboratory-scale spray-dryer on the characteristics of spray-dried powders containing two Pseudomonas aeruginosa bacteriophages exhibiting different morphotypes: a podovirus (LUZ19) and a myovirus (14-1). We optimized the production process for bacteriophage-loaded powders, with an emphasis on long-term storage under ICH (international conference on harmonization) conditions. D-trehalose-/L-isoleucine-containing bacteriophage mixtures were spray-dried from aqueous solutions using a Büchi Mini Spray-dryer B-290 (Flawil, Switzerland). A response surface methodology was used for the optimization of the spray-drying process, with the following as-evaluated parameters: Inlet temperature, spray gas flow rate, and the D-trehalose/L-isoleucine ratio. The dried powders were characterized in terms of yield, residual moisture content, and bacteriophage lytic activity. L-isoleucine has demonstrated a positive impact on the activity of LUZ19, but a negative impact on 14-1. We observed a negligible impact of the inlet temperature and a positive correlation of the spray gas flow rate with bacteriophage activity. After optimization, we were able to obtain dry powder preparations of both bacteriophages, which were stable for a minimum of one year under different ICH storage conditions (up to and including 40 °C and 75% relative humidity).

Industrial-Scale Hydrothermal Carbonization of Agro-Industrial Digested Sludge: Filterability Enhancement and Phosphorus Recovery

Hydrothermal carbonization (HTC) provides an attractive alternative method for the treatment of high-moisture waste and, in particular, digested sludge. HTC could reduce the costs and environmental risks associated with sludge handling and management. Although it is recognized that the dewaterability of hydrochars produced from digested sludge, even at mild temperatures (180–190 °C), is highly improved with respect to the starting material, the filterability of HTC slurries for the recovery of the solid material (hydrochar) still represents a challenge. This study presents the results of an investigation into the filterability of agro-industrial digested sludge HTC slurries produced by a C-700 CarboremTM HTC industrial-scale plant. The filterability of HTC slurries, produced at 190 °C for 1 h, with the use of acid solutions of hydrochloric acid, sulfuric acid or citric acids, was investigated by using a semi-industrial filter press. The use of sulfuric acid or citric acid solutions, in particular, significantly improved the filterability of HTC slurries, reducing the time of filtration and residual moisture content. The acid treatment also promoted the migration of heavy metals and phosphorus (P) in the HTC filtrate solution. This study demonstrates that P can be recovered via the precipitation of struvite in high yields, recovering up to 85 wt% by mass of its initial P content.

Assessment of the Effects of Back Sloping on Some Starter Culture Strains and the Organoleptic Qualities of their Yoghurt Products

Fermented milk is an essential commodity in Africa and beyond. Many techniques have been developed over time for the manufacture of different forms of yoghurt products. One of these Traditional methods includes back slopping). The advantages of this method include faster fermentation rates due to reduction in lag time, and subsequent production of relevant metabolites as well as allowing for a more reliable product formation on a consistent basis. The aim of this study was to better understand, the effects of back sloping on the microbial community as well as on the organoleptic characteristics of the yoghurts produced using the method. The model from this work could be used to study the dynamics of the microbial community associated with back-slopping practices and the understanding of possible associated defects in order to allow better control over the application of the method on commercial levels. We characterized the yoghurt produced from both microbial compositional study using culture-dependent morphological examinations on MRS, M17, Nutrient Agar and Potato dextrose Agar, as well as from organoleptic point of view. The results show that back sloping up to three-fold (batch) gave increasing acceptance but decreased afterwards. Acidification activity which determines proteolysis of casein for coagulation to take place also increased up to three folds. Residual lactose, syneresis and moisture content also decreased favourably by three fold order. Therefore, back sloping could be recommended on commercial level especially in the developing countries where facilities for consistent supply of pouched starter culture are limited because, aside the above mentioned advantages, this process also favours the growth of bacteria which release antimicrobial substances thereby ensuring the growth of the same species while reducing the growth of other organisms thereby preserving the products’ quality.

Empirical model of textile water retention in professional washing machines

This paper presents an experimental study and proposes an empirical model on the residual water content of a cotton load during the extraction phase of professional washing machines. Literature lacks data about spinning dewatering performances and thus a method is proposed to measure and predict water retention with respect to the main parameters that affect the washing process. The paper first provides a survey about retention models developed for different applications. It then introduces a new methodology to estimate residual moisture content as a function of time and centrifugal parameters, which avoids time consuming measurements. The methodology is proposed with respect to a customised washing cycle, which enables experimental validation with commercial washing machines. A scaling analysis is finally performed to verify the influence of the drum shape on retention performances. Results confirm the validity and versatility of the proposed model on a wide range of professional washing machines.

Mathematical Modeling of Drying Processes of Selected Fruits and Vegetables

AbstractThis study investigates the behavior of fruit and vegetable samples during drying. The experimental data are fitted to several different thin‐layer drying models. Regression analysis is used to determine model parameters, while statistical indicators serve to evaluate the goodness of fit. The power function model gives the best fit for all examined samples. Based on this model, different drying and heat storage technologies can be combined to ensure that the required residual moisture content of an agricultural product is reached. It is demonstrated on the case of a specific Togolese processing plant that under favorable conditions, fossil fuel consumption can be decreased by 33 %.

Effects of rearing system and microbial inoculation on black soldier fly larvae growth and microbiota when reared on agri-food by-products

Black soldier fly larvae (BSFL) are widely used in recycling and upcycling of nutrients in agri-food by-products, but low and inconsistent BSFL rearing performance (i.e. larval growth, bioconversion rate, and substrate reduction) has been identified as a key challenge. The aims of this research were two-fold: (1) validate an existing closed rearing system design; and (2) assess whether a microbial inoculum derived from the rearing residue increases rearing performance. In controlled bench-scale experiments, BSFL were reared on tomato pomace (TP) and white wine pomace (WWP), along with food waste as control substrate. The two aims were assessed based on the following response variables: larval mass, substrate reduction, residue properties (i.e. pH, temperature, moisture content), and larval intestinal and residue microbiota. Higher BSFL mass (by 5.1 mg dry mass) at harvest on WWP and substrate reduction on TP (by 11.7% dry mass) in the closed system compared to the open system confirmed the potential of closed systems for rearing performance improvements of agri-food by-products. The rearing system also affected the residual moisture content and temperature, but only had a small effect on microbiota. Performance improvements by the closed rearing system design may be outweighed by insufficient aeration with pasty substrates and higher operational efforts for aeration and larval separation from the high-moisture residues. In contrast to the rearing system design, addition of the residue-derived microbial inoculum did not result in improved performance, nor did it alter intestinal and residue microbiota. Missing performance improvements could have been due to absent or low numbers of probiotic bacteria. The success of microbial substrate supplementation could be improved by studying effects of larval-associated microbes and developing cultivation methods that selectively amplify the beneficial (yet unknown) members of the microbial community. Our investigations aimed to increase the valorisation of low-value agri-food by-products in BSFL rearing.

Dewatering fine solid suspension by using steam pressure filtration

Steam pressure filtration is the combination of mechanical and thermal in one equipment. This process shows the advantages in comparison to conventional pressure filtration by the characteristic of its distinction mechanism. Application of steam pressure filtration can be listed: dewatering the suspension of fine solid, remove the contaminant, dangerous chemical, dissolved ions, protecting the human health as well as the environment. This paper shows the mechanism of steam pressure filtration as well as the result of tests, the comparison related to the efficiency between steam pressure filtration and conventional pressure filtration. The steam pressure filtration shows the high efficiency in mechanical displacement phase in both input parameters: solid volume fraction of suspension and the height of filter cake. The residual moisture content and saturation of filter cake using steam pressure filtration are lower 10÷20% than those values of filter cake using conventional pressure filtration. Moreover, some preliminary tests taking account to the drying phase of steam pressure filtration are also showed. The moisture of fine material filter cakes is around 6÷13%. Through the result of tests, interpretation and discussion, the application of steam pressure filtration is possible in the field of mineral processing and metallurgy.

Cover crop residue moisture content controls diurnal variations in surface residue decomposition

The effect of cover crop (CC) surface residues on water, carbon, and nitrogen cycling in no-till systems depends in part on the water retention properties of decomposing residues and the extent of decomposition. This study (1) examined the effect of decomposition on residue water retention properties; (2) characterized diurnal variations in residue decomposition rates in response to changes in soil-residue-air environmental conditions; and (3) examined the diurnal relationships between cover crop surface residue decomposition and residue environment (moisture and temperature). Maximum gravimetric water content (θg) and characteristic water release curves were determined for red clover (Trifolium pratense L.) and cereal rye (Secale cereale L.) residues collected at 0, 4, 10, and 16 weeks after termination for red clover, and at 2, 5, and 18 weeks for cereal rye. In addition, residue carbon dioxide (CO2-C) flux, along with soil-residue-air environmental conditions, were measured diurnally for red clover at 4, 10, and 16 weeks after termination, and for cereal rye at 5 weeks after termination. Maximum residue θg decreased as decomposition progressed. Cover crop residue decomposition also influenced water release curves such that the water retained at any given water potential (ψresidue) declined with increasing decomposition. These decomposition-associated changes in residue water retention properties were strongly related to residue lignin concentrations. Cover crop surface residue CO2-C flux showed distinct diurnal patterns that were strongly related to ψresidue or residue θg. At a diurnal scale, residue CO2-C flux increased during the nighttime from 18:00 to 06:00 h when residues gain moisture from the atmosphere and soil, and decreased during the daytime from 06:00 to 18:00 h when residues lost moisture via evaporation. Increase in temperature decreased residue CO2-C flux due to moisture limitations. Therefore, CC surface residue decomposition models must address both diurnal changes in ψresidue and the changes in water retention properties as residues decompose.

Lyophilization Preserves the Intrinsic Cardioprotective Activity of Bioinspired Cell-Derived Nanovesicles.

Recently, bioinspired cell-derived nanovesicles (CDNs) have gained much interest in the field of nanomedicine due to the preservation of biomolecular structure characteristics derived from their parent cells, which impart CDNs with unique properties in terms of binding and uptake by target cells and intrinsic biological activities. Although the production of CDNs can be easily and reproducibly achieved with any kind of cell culture, application of CDNs for therapeutic purposes has been greatly hampered by their physical and chemical instability during long-term storage in aqueous dispersion. In the present study, we conceived a lyophilization approach that would preserve critical characteristics regarding stability (vesicles’ size and protein content), structural integrity, and biological activity of CDNs for enabling long-term storage in freeze-dried form. Compared to the lyoprotectant sucrose, trehalose-lyoprotected CDNs showed significantly higher glass transition temperature and lower residual moisture content. As assessed by ATR-FTIR and far-UV circular dichroism, lyophilization in the presence of the lyoprotectant effectively maintained the secondary structure of cellular proteins. After reconstitution, lyoprotected CDNs were efficiently associated with HeLa cells, CT26 cells, and bone marrow-derived macrophages at a rate comparable to the freshly prepared CDNs. In vivo, both lyoprotected and freshly prepared CDNs, for the first time ever reported, targeted the injured heart, and exerted intrinsic cardioprotective effects within 24 h, attributable to the antioxidant capacity of CDNs in a myocardial ischemia/reperfusion injury animal model. Taken together, these results pave the way for further development of CDNs as cell-based therapeutics stabilized by lyophilization that enabled long-term storage while preserving their activity.

In-line monitoring of the application weight of an adhesion promoter and the residual moisture content in textile finishing by hyperspectral imaging using a NIR multiplex spectrometer system

The application weight of an adhesion promoter applied to a textile fabric by impregnation as well as the residual moisture content of the material after drying were monitored by hyperspectral imaging. In order to be able to monitor the current state of a complete textile web, which may have a working width of several meters, a multiplex NIR spectrometer system instead of a hyperspectral camera was used. The optical ports of the multiplexer were connected to a few tens of individual fiber-optic sensors, whose front ends were distributed evenly across the working width of the web. The spectrometer unit covered a spectral range from 1100 to 2200 nm. Chemometric techniques, in particular partial least squares (PLS) regression, were used to extract quantitative values of both parameters of interest from the recorded spectral data. The root mean square errors of prediction (RMSEP) determined in an external validation step were found to be 1.4 g/m2 for the application weight and 0.46 wt% for the moisture content, which are roughly the same error limits as those in a previous study using a hyperspectral camera. Consequently, application weight and residual moisture after drying can be predicted in-line with high precision. Moreover, the spatial distribution of both parameters across the textile was investigated. Although the resolution of the multiplex spectrometer system is one order of magnitude lower than that of a NIR hyperspectral camera, inhomogeneities in both application weight and moisture content could be clearly revealed provided that their size was larger than the limit given by the spatial resolution. The results prove that a scalable NIR multiplex spectrometer system instead of a NIR camera can be used for monitoring of the actual state of the finished material across the overall width of the web. Such data may be used for process control in textile converting and similar processes.

STUDY ON THE PRODUCTION PROCESS OF SINGLE DOSE MEASLES-RUBELLA COMBINED VACCINE AT POLYVAC

Center for Research and Production of Vaccines and Biologicals (POLYVAC) has conducted “Study on the production process of single dose measles-rubella combined vaccine (MRVAC)” (1dose/vial) in lyophilized form to make it convenient to use for vaccination services and export. The results have determined the formulation of MRVAC final bulk, freeze-dried process. The quality of researched products met WHO and Vietnam Pharmacopoeia V standards in both visual tests of lyophilized vaccine cake and after being reconstituted with sterile water for injection, the titer of measles virus ranges from 4.03 to 4.28 lgPFU/0.5mL and titer of rubella virus is from 3.79 to 3.98 lgPFU/0.5 mL. Results on thermal stability test when incubating the vaccine at 37oC/7days, the titer of measles virus decreased from 0.79 to 0.96 lgPFU/ 0.5mL and titer of rubella virus decreased from 0 to 0.18 lgPFU/0.5mL. Residual moisture content ranges from 0.35 to 0.72%. pH of vaccine is stable, ranges from 7.42 to 7.62.

In-line monitoring of the application weight of an adhesion promoter and the residual moisture content in textile finishing by hyperspectral imaging using a NIR camera

Hyperspectral imaging was used for monitoring of both the application weight of an adhesion promoter for rubber applied to a polyester fabric by impregnation and the residual moisture in the fabric after drying at the end of the finishing process. A NIR camera with a spectral range from 1320 to 1900 nm was used for imaging. Quantitative data were derived from the spectra by chemometric methods using partial least squares (PLS) regression. Reference data for calibration and validation were determined by gravimetry. The root mean square errors of prediction (RMSEP) for the application weight and the moisture content were found to be 1.2 g/m² (for a probed range up to 25 g/m²) and 0.34 wt% (for water contents up to 10 wt%), respectively. Moreover, nonuniformities in both application weight and drying could be clearly uncovered. Mean values for application weight and moisture content obtained by averaging of the individual predictions from all pixels of each spectral image were found to show excellent correlation with the corresponding reference values from gravimetry. The results reveal that hyperspectral imaging with a NIR camera in combination with the PLS algorithm and adequate calibration is able to provide data with sufficient precision for in-line monitoring of both technical parameters and confirm the efficiency of this analytical approach for process control in technical textile converting.

Preparation and evaluation of vancomycin spray-dried powders for pulmonary delivery

The aim of the current study was to achieve a dry powder formulation of vancomycin by spray drying whilst evaluating the effect of pH and excipient type and percentage used in formulation on particle characteristics and aerosolization performance. A D-optimal design was applied to optimize the formulation comprising vancomycin and two main excipient groups; a carbohydrate bulking agent (lactose, mannitol or trehalose) and a second excipient (hydroxypropyl beta-cyclodextrin or L-leucine) at pH 4 and 7. The physicochemical properties of particles (size, morphology, crystallinity state, residual moisture content), stability, and aerosolization characteristics were investigated. Using the combination of two excipients increased the fine particle fraction of powder emitted from an Aerolizer® device at a flow rate of 60 L/min. Hydroxypropyl beta-cyclodextrin showed more potential than L-leucine in aerosolization capabilities. Stability studies over 3 months of storage in 40 °C and 75% relative humidity suggested a good physical stability of the optimized formulation containing 17.39% hydroxypropyl beta-cyclodextrin along with 29.61% trehalose relative to the amount of drug at pH 4. Use of two excipients including trehalose and hydroxypropyl beta-cyclodextrin with a total weight ratio of 47% relative to the amount of drug is appropriate for the preparation of vancomycin dry powder formulation for inhalation.

Applicability of Raman and near-infrared spectroscopy in the monitoring of freeze-drying injectable ibuprofen

The freeze-drying process is an expensive, time-consuming and rather complex process. Therefore, process analytical technology (PAT) tools have been introduced to develop an optimized process and control critical process parameters, which affect the final product quality. The aim of the present work was to study the applicability of at-line near-infrared (NIR) and Raman spectroscopy approach in the monitoring of the freeze-drying process. Freeze-dried powders, which were developed previously, were manufactured as a multi-component system, containing ibuprofen (IBP). The NIR proved to be a useful tool for the monitoring of the freeze-drying process, since it was able to determine residual moisture content (RMC) and hence predict its values by using the partial least square (PLS) model. In addition, the evaluation of the correlation between the NIR and off-line HPLC IBP content results showed that NIR spectra were consistent with the HPLC measurements, even though overlapping absorption bands in multi-component system were observed. This research also studied the ability of using the at-line Raman measurements for the evaluation of the crystallinity and polymorphic transformations during the process, such as IBP ionization and mannitol polymorphism. The results were in correlation with XRPD results, but parameters of PLS models were not optimal. Nevertheless, this approach still assured better process understanding. To conclude, high applicability of the at-line NIR in the monitoring of the freeze-dried powder production was successfully demonstrated, suggesting that it can be used as a single tool to monitor RMC and IBP content as well as process deviations during the freeze-drying process.

The Influence of Ferrous Metallurgy Waste in the Aktobe Region on the Frost Resistance of Ceramic Bricks Based on Low-Melting Clay

The research objective is studying the effect of tailing slurry of chromite ore beneficiation on the phase composition and frost resistance of ceramic bricks obtained based on low-melting clay. For the study, two compositions were taken, % wt.: 1) the optimal composition ─ low-melting clay of the Ilek deposit - 70, tailing slurry of chromite ore beneficiation, 2) the reference composition ─ low-melting clay of the Ilek deposit - 100. Raw materials were crushed to pass through a sieve No. 1.0 mm; then, the components were thoroughly mixed. The bricks were prepared by melting at a batch moisture content of 22 %. The mold bricks were dried to a residual moisture content of 5 % max. The dried bricks were fired at temperatures, оС: 950 (the glass phase emergence), and 1,050 (the final brick firing temperature). The increased content of iron oxide (Fe2O3=12.3 %) and alkali oxides (R2O=3.2 %) in the tailing slurry of chromite ore beneficiation contributed to the liquid phase emergence at 950 оС. Colorless, yellowish, and brown glasses with refractive indices N within 1.50-1.54, forming as a result of melting of spars and mixed-layer clayey formations, were observed under the microscope in the studied prototypes of composition No. 1 at a firing temperature of 950 °C. In the composition No. 2, a liquid phase also emerges, but in smaller quantities. Adding tailing slurry of chromite ore beneficiation to ceramic masses contributes to the formation of anorthite and glass phase in prototypes based on low-melting clay at a firing temperature of 950 °C. An increase in the firing temperature to 1,050 °C increases the content of the glass phase and anorthite, which significantly improves the frost resistance of ceramic bricks.

Current Approaches of Preservation of Cells During (freeze-) Drying.

The widespread application of therapeutic cells requires a successful stabilization of cells for the duration of transport and storage. Cryopreservation is currently considered the gold standard for the storage of active cells; however, (freeze-) drying cells could enable higher shelf life stability at ambient temperatures and facilitate easier transport and storage. During (freeze-) drying, freezing, (primary and secondary) drying and also the reconstitution step pose the risk of potential cell damage. To prevent these damaging processes, a wide range of protecting excipients has emerged, which can be classified, according to their chemical affiliation, into sugars, macromolecules, polyols, antioxidants and chelating agents. As many excipients cannot easily permeate the cell membrane, researchers have established various techniques to introduce especially trehalose intracellularly, prior to drying. This review aims to summarize the main damaging mechanisms during (freeze-) drying and to introduce the most common excipients with further details on their stabilizing properties and process approaches for the intracellular loading of excipients. Additionally, we would like to briefly explain recently discovered advantages of drying microorganisms, sperm, platelets, red blood cells, and eukaryotic cells, paying particular attention to the drying technique and residual moisture content.

Cycle Development in a Mini-Freeze Dryer: Evaluation of Manometric Temperature Measurement in Small-Scale Equipment

The objective of this research was to assess the applicability of manometric temperature measurement (MTM) and SMART™ for cycle development and monitoring of critical product and process parameters in a mini-freeze dryer using a small set of seven vials. Freeze drying cycles were developed using SMART™ which automatically defines and adapts process parameters based on input data and MTM feedback information. The freeze drying behavior and product characteristics of an amorphous model system were studied at varying wall temperature control settings of the cylindrical wall surrounding the shelf in the mini-freeze dryer. Calculated product temperature profiles were similar for all different wall temperature settings during the MTM-SMART™ runs and in good agreement with the temperatures measured by thermocouples. Product resistance profiles showed uniformity in all of the runs conducted in the mini-freeze dryer, but absolute values were slightly lower compared to values determined by MTM in a LyoStar™ pilot-scale freeze dryer. The resulting cakes exhibited comparable residual moisture content and optical appearance to the products obtained in the larger freeze dryer. An increase in intra-vial heterogeneity was found for the pore morphology in the cycle with deactivated wall temperature control in the mini-freeze dryer. SMART™ cycle design and product attributes were reproducible and a minimum load of seven 10R vials was identified for more accurate MTM values. MTM-SMART™ runs suggested, that in case of the wall temperature following the product temperature of the center vial, product temperatures differ only slightly from those in the LyoStar™ freeze dryer.

Deployment of response surface methodology to optimize microencapsulation of peroxidases from turnip roots (Brassica rapa L.) by double emulsion in PLA polymer.

In order to improve the preservation conditions and stability of peroxidase catalytic properties, a number of immobilization techniques have been widely developed. In this context, we set as objective, the optimization of synthesis and stability of microcapsules of peroxidases (POD) from turnip using polylactic acid (PLA) polymer with the double emulsion technique. The surfactant, polymer, and peroxidase concentrations were the optimized parameters. According to the results obtained using the Box-Behnken design, the optimal parameters found were 1.55% of PVA, 55mg/mL of peroxidases, and 30mg/mL of PLA polymer with an encapsulation efficiency of 57.29%. The scanning electron microscopy morphological characterization of the optimized microcapsules showed a regular spherical structure. Fourier transform infrared spectroscopy identified the specific functional groups and chemical bonds before and after microencapsulation. The elaborated microcapsules were characterized by an average size of 200µm(mainly from 150 to 500µm)with a low residual moisture content (2.26%) and the encapsulated peroxidases showed better thermal stability. The in vitro release of peroxidases confirmed that the microcapsules have an excellent sustained release in simulated gastric digestion. Encapsulated peroxidases' storage under 25 and 4°C displays a good residual POD activity with about 60% of initial activities during 80 days of storage, whereas free POD losses its initial activity within 15 and 30 days, respectively. The obtained results are promising for the development of effective therapeutic treatment of some intestinal troubles due to oxidative stress. PRACTICAL APPLICATION: Brassica rapa L. root is well known for its richness on peroxidases and thus presents an interesting potential for developing high added value products. In order to preserve the activity of extracted peroxidases (POD) from turnip roots, microencapsulation was optimized using a polylactic acid polymer. The encapsulated POD showed the maintenance of its activity under the effect of different storage conditions (time and temperature) and demonstrated resistance to gastric acidity. According to the obtained results, the encapsulation of peroxidases opens up medicine and pharmaceutical applications such as intestinal and colic protection against inflammations.