Thawing of cryopreserved sperm from domestic animals: Impact of temperature, time, and addition of molecules to thawing/insemination medium.

In recent decades, there has been a growing interest in optimizing the protocols intended to sperm cryopreservation in domestic animals. These protocols include initial cooling, freezing, and thawing. While different attempts have been devised to improve sperm cryopreservation, the efficiency of this reproductive biotechnology is still far from being optimal. Furthermore, while much attention in improving cooling/freezing, less emphasis has been made in how thawing can be ameliorated. Despite this, the conditions through which, upon thawing, sperm return to physiological temperatures are much relevant, given that these cells must travel throughout the female genital tract until they reach the utero-tubal junction. Moreover, the composition of the media used for artificial insemination (AI) may also affect sperm survival, which is again something that one should bear because of the long journey that sperm must make. Furthermore, sperm quality and functionality decrease dramatically during post-thawing incubation time. Added to that, the deposition of the thawed sperm suspension devoid of seminal plasma in some species during an AI is accompanied by a leukocyte migration to the uterine lumen and with it the activation of immune mechanisms. Because few reviews have focused on the evidence gathered after sperm thawing, the present one aims to compile and discuss the available information concerning ruminants, pigs and horses.

Rapid thawing of frozen bull spermatozoa by transient exposure to 70 °C improves the viability, motility and mitochondrial health.

Up to now, the definitive conclusion of the positive effects of rapid transient thawing at higher temperatures for shorter durations has not been obtained yet and is still under discussion due to some contradictory findings and limited assessment of post-thawed parameters. The purpose of the current study was to evaluate the effectiveness of rapid thawing in water at 70 °C by using various post-thawed parameters of frozen bull spermatozoa. Experiment 1, monitoring the change of temperature inside frozen bull straw thawed in water at different temperatures. Experiment 2, evaluation of various post-thawed characteristics of frozen bull spermatozoa thawed in water at different temperatures by using a computer-assisted sperm analysis, flow cytometry and immunocytochemistry. The time it took for the temperature inside the straw to warm up to 15 °C was nearly twice as faster when the straw was thawed in 70 °C water compared with 39 °C. Although there were differences among bulls, viability, motility, and mitochondrial membrane potential of spermatozoa thawed at 70 °C for 8 seconds and stabilized at 39 °C for 52 seconds were significantly higher than those of controls (thawed at 39 °C for 60 seconds) at 0 and 3 h after thawing. Just after thawing, however, there were no differences in acrosome integrity and distribution of phospholipase C zeta1, whereas mitochondrial reactive oxygen species production was significantly lower in spermatozoa thawed at 70 °C. From these results, we conclude that rapid thawing at 70 °C and then stabilization at 39 °C significantly improves viability, motility and mitochondrial health of bull spermatozoa rather than conventional thawing at 39 °C. The beneficial effect of rapid transient thawing could be due to shorter exposure to temperatures outside the physiological range, consequently maintaining mitochondrial health.

Specific antioxidant enzymes are involved in the freeze-thawing response of industrial baker's yeasts.

In this study, the biochemical basis of resistance to slow freezing and thawing (F-T) stress was explored in two baker yeast industrial strains of Saccharomyces cerevisiae that presented differential tolerance to freezing in order to be in the frozen bakery industry. Strain Y8, used commercially in sweet baking doughs, exhibited greater stress tolerance than Y9, a strain employed in regular doughs. Survival of Y8 was higher than that of Y9 (30% vs 12%) after F-T or other reactive oxygen species (ROS) inducing stresses compared to their non-stressed controls. The superior F-T tolerance of Y8 was related to its lower ROS accumulation capacity, determined by fluorometry in cell-free extracts and in vivo, by fluorescence microscopy upon F-T, being Y8 ROS accumulation 2-fold lower than that of Y9. That, in turn, could be positively associated with Y8's higher constitutive activities of cytosolic catalase (CAT) and superoxide dismutase by a significant activation (25%) of Y8 CAT after F-T. That would complement the protective effects of other protectant molecules like trehalose, present at high concentration in this strain.

Acid emulsions stabilized by soy whey concentrates and soluble soybean polysaccharides: Role of biopolymer interaction strategies on stability against environmental stresses.

This article focuses on the evaluation of different interaction strategies between soy whey concentrates (SWC) and soluble soybean polysaccharides (SSPS) at pH 3.0 on the emulsion stability against freeze-thawing and mechanical stirring. Emulsions were prepared from aqueous dispersions of both biopolymers (3.0% w/w SSPS and SWC, 1:1 mass ratio) and sunflower oil (10% w/w) by aqueous phase complexation (APC), interfacial complexation (IC) and interfacial complexation and sonication (ICS). SWC control emulsion was a poor emulsifying ability; SSPS addition, through the APC and ICS strategies, noticeably improved the SWC emulsifying properties. ICS emulsions showed the highest stability to environmental stresses, due a combination of low initial particle size, flocculation degree and steric hindrance promoted by the presence of SSPS chains at the interface. This study provides valuable information forthe utilization of whey soy proteins in acid dispersed systems stable to environmental stresses.

Collection, cryopreservation and thawing of stem cells for children weighing less than 25 Kg with high-risk neuroblastoma: A single center results in Morocco

ABSTRACT Introduction: An important component of the advances made in neuroblastoma treatment has been the use of peripheral blood stem cells to support high-dose chemotherapy. In this study, we report our experience on a series of small children who have undergone standard and large volume leukaphersis (LVL) procedures, provide an update on a single institution's experience with cryopreservation of autologous peripheral blood stem cells (PBSCs), using 10% dimethyl sulfoxide (DMSO) and applying post-thaw DMSO depletion and analyze a number of variables that may affect viability. Methods: A total of 36 aphereses were performed on 29 children weighing less than 25 kg between July 2016 and October 2019 at the Ibn Sina university hospital. Results: Seven females and twenty-two males, median bodyweight 14 kg (9 - 22). A single apheresis was sufficient to obtain at least 3 × 106/kg body weight (BW) of CD34+ cells in 82.8% of the cases. The LVL was performed in 22 aphereses. A median number of 5.9 × 106/ kg CD34 cells were collected per apheresis. A total of 60 PBSC samples were cryopreserved and 46 samples were infused. The mean cell viability percentage decreased from 94.75 ± 1.14% before freezing to 70.84 ± 8.6% after thawing (p < 0.001). No correlation was found between post-thaw viability and storage time (r = -0.233; p = 0.234) or number of total nucleated cells (r = 0.344; p = 0.073). Conclusion: Leukapheresis is safe and feasible in small pediatric patients if the appropriate measures are used. Cryopreservation poses numerous challenges, especially a decrease in cell viability after thawing.

Improving Cell Recovery: Freezing and Thawing Optimization of Induced Pluripotent Stem Cells.

Achieving good cell recovery after cryopreservation is an essential process when working with induced pluripotent stem cells (iPSC). Optimized freezing and thawing methods are required for good cell attachment and survival. In this review, we concentrate on these two aspects, freezing and thawing, but also discuss further factors influencing cell recovery such as cell storage and transport. Whenever a problem occurs during the thawing process of iPSC, it is initially not clear what it is caused by, because there are many factors involved that can contribute to insufficient cell recovery. Thawing problems can usually be solved more quickly when a certain order of steps to be taken is followed. Under optimized conditions, iPSC should be ready for further experiments approximately 4-7 days after thawing and seeding. However, if the freezing and thawing protocols are not optimized, this time can increase up to 2-3 weeks, complicating any further experiments. Here, we suggest optimization steps and troubleshooting options for the freezing, thawing, and seeding of iPSC on feeder-free, Matrigel™-coated, cell culture plates whenever iPSC cannot be recovered in sufficient quality. This review applies to two-dimensional (2D) monolayer cell culture and to iPSC, passaged, frozen, and thawed as cell aggregates (clumps). Furthermore, we discuss usually less well-described factors such as the cell growth phase before freezing and the prevention of osmotic shock during thawing.

Impact of environmental stresses on the stability of acidic oil-in-water emulsions prepared with tofu whey concentrates.

The emulsifying properties of tofu-whey concentrates (TWCs) at pH 3.0, 4.0, and 5.0, and the stability of the resultant oil-in-water emulsions against freeze-thawing (24 h, -20 °C) and controlled or mechanical stress (orbital stirring at 275 rpm, 40 min) were addressed. TWCs were prepared from tofu-whey by heating at 50 °C (8.0 kPa) or 80 °C (24.0 kPa), dialysis (4 °C, 48 h), and freeze-drying, giving the samples TWC50 and TWC80, respectively. The particle size and interfacial properties at the oil/water interface were measured. Emulsions were prepared by mixing the TWC aqueous dispersions (1.0% protein w/w) and refined sunflower oil (25.0% w/w) by high-speed and ultrasound homogenization. The preparation of TWCs at higher temperatures (80 °C) promoted the formation of species of larger particle size, a slight decrease of interfacial activity, and the adsorption of more rigid biopolymer structures associated with an increase of film viscoelasticity in interfacial rheology measurements. The emulsifying properties of both concentrates were enhanced with decreasing pH (5.0-3.0), through a significant decrease of particle size (D4,3) and flocculation degree (FD), but only those prepared with TWC80 exhibited higher stability to freeze-thawing and mechanical stress at pH 3.0. This could be ascribed to a combination of low initial D4,3 and FD values, high protein load, and the presence of rigid species that impart high viscoelasticity to the oil/water interface. These results would be of great importance for the utilization of TWCs as food emulsifiers in acidic systems to impart high stability to environmental stresses.

Collection, cryopreservation and thawing of stem cells for children weighing less than 25 Kg with high-risk neuroblastoma: A single center results in Morocco.

INTRODUCTION: An important component of the advances made in neuroblastoma treatment has been the use of peripheral blood stem cells to support high-dose chemotherapy. In this study, we report our experience on a series of small children who have undergone standard and large volume leukaphersis (LVL) procedures, provide an update on a single institution's experience with cryopreservation of autologous peripheral blood stem cells (PBSCs), using 10% dimethyl sulfoxide (DMSO) and applying post-thaw DMSO depletion and analyze a number of variables that may affect viability. METHODS: A total of 36 aphereses were performed on 29 children weighing less than 25 kg between July 2016 and October 2019 at the Ibn Sina university hospital. RESULTS: Seven females and twenty-two males, median bodyweight 14 kg (9 - 22). A single apheresis was sufficient to obtain at least 3 × 106/kg body weight (BW) of CD34+ cells in 82.8% of the cases. The LVL was performed in 22 aphereses. A median number of 5.9 × 106/kg CD34 cells were collected per apheresis. A total of 60 PBSC samples were cryopreserved and 46 samples were infused. The mean cell viability percentage decreased from 94.75 ± 1.14% before freezing to 70.84 ± 8.6% after thawing (p < 0.001). No correlation was found between post-thaw viability and storage time (r = -0.233; p = 0.234) or number of total nucleated cells (r = 0.344; p = 0.073). CONCLUSION: Leukapheresis is safe and feasible in small pediatric patients if the appropriate measures are used. Cryopreservation poses numerous challenges, especially a decrease in cell viability after thawing.

Chitosan Edible Coating as Decontaminant During Water Thawing of Frozen Broiler Carcasses

The present study was designed to evaluate the effects of chitosan edible coating applications on the sensory, physicochemical, and bacterial load on chicken during thawing. Edible coatings prepared with 0.5 &1% chitosan in acetic acid (0.5%), was used as thawing solution. The frozen chicken was submerged for 2 hrs in tap water as control, 0.5 &1% chitosan treatments. Chitosan 1% coating improves tenderness and in turn overall acceptability scores. The result of shear force analysis emphasized the tenderness sensory scores of cooked broilers. Application of chitosan coat reduces pH value, APC, Psychrotrophic count, with significant (p<0.05) reduction in thawed broilers with 1% chitosan coat. Therefore, commercial chitosan can be applied in water thawing of frozen broiler to improve the quality characteristics economically. The results demonstrate that the application of chitosan can be an effective method for reducing contamination in chicken meat during thawing.(AU)

Administration of Dietary Microalgae Ameliorates Intestinal Parameters, Improves Body Weight, and Reduces Thawing Loss of Fillets in Broiler Chickens: A Pilot Study.

This pilot investigation aimed at studying the feasibility of using a low dose (0.2%) of dietary microalgae as a means of improving intestinal morphometry, body weight, and selected meat quality parameters in broilers. A total of 72 one-day-old ROSS 308 male chicks were randomly separated into four groups; three experimental pens in which the birds were fed with biomass from Tysochrysis lutea, Tetraselmis chuii, and Porphyridium cruentum over 30 days and a control group. T. chuii and P. cruentum had a positive effect with regard to body weight. In treated animals, duodenal and ileal sections showed characteristic tall and thin villi, with serrated surfaces and goblet cell differentiation. In both sections, values of the villus-height-to-crypt-depth ratio were increased by microalgae ingestion. The thawing weight loss of fillets was reduced in T. chuii-fed animals. The positive effects exerted by T. chuii and P. cruentum on intestinal architecture were associated with the improved body weight. Arguably, these outcomes exhibit the potential of using these species to enhance growth performance in broiler chickens by promoting gut homeostasis and thus nutrient absorption.

Dripping test to assessment the water content in frozen chicken carcases commercialized in Ji-Paraná, Rondônia, Brazil / Dripping test para avaliação do teor de água em carcaças de frango congeladas comercializadas em Ji-Paraná, Rondônia, Brasil

The growth in demand for chicken meat is due to the increase in demand for white meat, as they are considered tasty and at an attractive price. Therefore, the search for quality is essential. In Brazil, the water loss due to the melting of the carcasses is controlled by companies and by the Ministry of Agriculture, Livestock and Supply (MAPA) and, frequently, they analyze water loss from the carcasses above the limits required by the legislation. Given the assumption, the aimed of this study was to evaluate the water losses due to thawing in frozen chicken carcasses marketed in the municipality of Ji-Paraná, Rondônia, Brazil. There 25 carcasses of whole frozen chickens were evaluated, from six brands, lots and different establishments, submitted to standardized conditions for the performance of the Dripping test, in order to verify the percentage of water absorbed by the carcasses. It was found that 48% of the samples showed water loss beyond that allowed by the current legislation, which is 6%. When observing that almost half of the evaluated carcasses showed irregularities in relation to the legislation, it is understood that the companies that supply these products should be better inspected, carrying out Dripping test analyzes periodically to reduce or eliminate this type of crime.

O crescimento da demanda de carne de frango se deve ao aumento da procura de carnes brancas, por serem con-sideradas saborosas e com preço atrativo. Por isso, a busca pela qualidade é imprescindível. No Brasil, a perda de água pelo degelo das carcaças é controlada pelas empresas e pelo Ministério da Agricultura Pecuária e Abastecimento (MAPA) e, fre-quentemente, analisam perda de água das carcaças acima dos limites exigidos pela legislação. Diante do pressuposto, o obje-tivo desse estudo foi avaliar as perdas de água por degelo em carcaças de frango congeladas comercializadas no município de Ji-Paraná, Rondônia. Foram avaliadas 25 carcaças de frangos congelados inteiros, de seis marcas, lotes e estabelecimentos dis-tintos, submetidos a condições padronizadas para a realização do Dripping test, com a finalidade de verificar o percentual de água absorvida pelas carcaças. Constatou-se que 48% das amostras apresentaram perda de água além do permitido pela legis-lação vigente, que é de 6%. Ao observar que quase a metade das carcaças avaliadas apresentaram irregularidades frente à legis-lação, entende-se que as empresas fornecedoras desses produtos devem ser melhor fiscalizadas, realizando análises de Dripping test periodicamente para reduzir ou eliminar esse tipo de delito.

Dripping test to assessment the water content in frozen chicken carcases commercialized in Ji-Paraná, Rondônia, Brazil / Dripping test para avaliação do teor de água em carcaças de frango congeladas comercializadas em Ji-Paraná, Rondônia, Brasil

The growth in demand for chicken meat is due to the increase in demand for white meat, as they are considered tasty and at an attractive price. Therefore, the search for quality is essential. In Brazil, the water loss due to the melting of the carcasses is controlled by companies and by the Ministry of Agriculture, Livestock and Supply (MAPA) and, frequently, they analyze water loss from the carcasses above the limits required by the legislation. Given the assumption, the aimed of this study was to evaluate the water losses due to thawing in frozen chicken carcasses marketed in the municipality of Ji-Paraná, Rondônia, Brazil. There 25 carcasses of whole frozen chickens were evaluated, from six brands, lots and different establishments, submitted to standardized conditions for the performance of the Dripping test, in order to verify the percentage of water absorbed by the carcasses. It was found that 48% of the samples showed water loss beyond that allowed by the current legislation, which is 6%. When observing that almost half of the evaluated carcasses showed irregularities in relation to the legislation, it is understood that the companies that supply these products should be better inspected, carrying out Dripping test analyzes periodically to reduce or eliminate this type of crime.(AU)

O crescimento da demanda de carne de frango se deve ao aumento da procura de carnes brancas, por serem con-sideradas saborosas e com preço atrativo. Por isso, a busca pela qualidade é imprescindível. No Brasil, a perda de água pelo degelo das carcaças é controlada pelas empresas e pelo Ministério da Agricultura Pecuária e Abastecimento (MAPA) e, fre-quentemente, analisam perda de água das carcaças acima dos limites exigidos pela legislação. Diante do pressuposto, o obje-tivo desse estudo foi avaliar as perdas de água por degelo em carcaças de frango congeladas comercializadas no município de Ji-Paraná, Rondônia. Foram avaliadas 25 carcaças de frangos congelados inteiros, de seis marcas, lotes e estabelecimentos dis-tintos, submetidos a condições padronizadas para a realização do Dripping test, com a finalidade de verificar o percentual de água absorvida pelas carcaças. Constatou-se que 48% das amostras apresentaram perda de água além do permitido pela legis-lação vigente, que é de 6%. Ao observar que quase a metade das carcaças avaliadas apresentaram irregularidades frente à legis-lação, entende-se que as empresas fornecedoras desses produtos devem ser melhor fiscalizadas, realizando análises de Dripping test periodicamente para reduzir ou eliminar esse tipo de delito.(AU)

The effect of fresh IVF cycle characteristics on frozen embryo transfer (FET) outcomes.

OBJECTIVE: To determine the effect of fresh IVF/ICSI cycles on FET cycle embryo and pregnancy outcomes. METHODS: This retrospective cohort study included data from the medical records of 104 FET cycles performed from January 2014 to December 2016. Embryos were previously vitrified and then thawed for embryo transfer. Statistical significance was established at p<0.05. The main endpoints were FET cycle survival and pregnancy rates. RESULTS: A total of 104 FET cycles were analyzed for survival; 94 showed good progression and 84 achieved embryo transfers. Patients with secondary infertility achieved significantly higher pregnancy rates - 6/38 (15.8%) vs. 18/46 (39.1%) (p<0.018). Stimulation with FSH/LH resulted in more significant embryo progression, 38/48 (79.2%) vs. 28/46 (60.9%) in the FSH group (p=0.01). Patients who got pregnant from fresh cycles had the highest pregnancy rates in FET cycles (p<0.0001). Lower numbers of frozen embryos correlated with higher pregnancy rates (p=0.048). Embryos frozen on day 2 or 3 had the most significant progression (p<0.0001). Freeze-thaw intervals >12 months yielded higher pregnancy rates, 13/30 (43%), vs. 11/54 (20.4%) (p=0.025). CONCLUSION: Patient pregnancy in fresh cycles is a good prognostic factor for FET cycle success. Delaying FET by more than 12 months might result in higher pregnancy rates.

Effects of freezing and thawing on microbiological and physical-chemical properties of dry-aged beef.

This study evaluated the effects of freezing, prior to and after dry aging, on the microbiological and physical-chemical quality of beef. Strip loins (n = 24) from 12 carcasses were assigned to four treatments: non-frozen dry aging (Dry); dry aging, steak fabrication, freezing and slow thawing (Dry + ST); freezing, fast thawing (FT; 20 °C/15 h) and dry aging (FT + Dry); freezing, slow thawing (ST; 4 °C/48 h) and dry aging (ST + Dry). Freezing conditions were - 20 °C/28 days and dry aging conditions were 2 °C/70% relative humidity, for 28 days. Freezing prior to dry aging did not affect the microbial counts compared to Dry. However, FT + Dry and ST + Dry increased (16%) total process loss (P < .05) compared to Dry and Dry+ST. Moreover, freezing changed volatile compounds profile. Thus, freezing prior to dry aging was not a feasible process due to increased process loss, while freezing after dry aging was considered a viable alternative to preserve the steaks without compromising beef physical-chemical traits.

Thawing rate predicts acute pulmonary vein isolation after second-generation cryoballoon ablation

OBJECTIVE: To evaluate whether thawing rate could be a novel predictor of acute pulmonary vein isolation (PVI) and explore the predictive value of thawing rate as a factor ensuring long-term PVI (vagus reflex). METHODS: A total of 151 patients who underwent cryoballoon ablation for atrial fibrillation (AF) were enrolled in this retrospective study between January 2017 and June 2018. The thawing rate was calculated using the thawing phase of the cryoablation curve. Receiver operating characteristic (ROC) curve was used to analyze the predictive value of the thawing rate for acute PVI and vagus reflex. RESULTS: ROC curve analyses revealed that the interval thawing rate at 15°C (ITR15) was the most valuable predictor of PVI, with the highest area under curve (AUC) value of the ROC curve. The best cut-off value of ITR15 for PVI was ≤2.14°C/S and its sensitivity and specificity were 88.62% and 67.18%, respectively. In addition, the ITR15 of the successful PVI group after cryoballoon ablation was significantly slower than the failed PVI group. ITR15 was a predictor of vagus reflex and the occurrence of vagus reflex group had a slower ITR15 compared to the non-occurrence group. CONCLUSIONS: Thawing rate was a novel predictor of acute PVI and the ITR15 was the most valuable predictor of acute PVI. In addition, ITR15 was a predictive factor ensuring long-term PVI (vagus reflex). Our study showed that thawing rate may serve in the early identification of useless cryoballoon ablation.

Human Leukocyte Antigen and Red Blood Cells Impact Umbilical Cord Blood CD34+ Cell Viability after Thawing.

Hematopoietic progenitor cell (HPC) transplantation is a treatment option for malignant and nonmalignant diseases. Umbilical cord blood (UCB) is an important HPC source, mainly for pediatric patients. It has been demonstrated that human leukocyte antigen (HLA) matching and cell dose are the most important features impacting clinical outcomes. However, UCB matching is performed using low resolution HLA typing and it has been demonstrated that the unnoticed mismatches negatively impact the transplant. Since we found differences in CD34+ viability after thawing of UCB units matched for two different patients (p = 0.05), we presumed a possible association between CD34+ cell viability and HLA. We performed a multivariate linear model (n = 67), comprising pre-cryopreservation variables and high resolution HLA genotypes separately. We found that pre-cryopreservation red blood cells (RBC), granulocytes, and viable CD34+ cell count significantly impacted CD34+ viability after thawing, along with HLA-B or -C (R2 = 0.95, p = 0.01; R2 = 0.56, p = 0.007, respectively). Although HLA-B*40:02 may have a negative impact on CD34+ cell viability, RBC depletion significantly improves it.

Freezing and drying of pink grapefruit-lycopene encapsulated in Ca(II)-alginate beads containing galactomannans.

Lycopene extracted from pink grapefruit was encapsulated on Ca(II)-alginate beads with the addition of trehalose and galactomannans to improve its stability against freezing and drying. Three galactomannans of different physicochemical properties were studied since their inclusion affects both loading efficiency and release of lycopene in wet beads; however, there is no information about their performance during freezing and dehydration operations. The remaining lycopene and its stability towards isomerization were analyzed in beads subjected to continuous freezing, freezing/thawing cycles and vacuum- and freeze-drying. Isothermal crystallization studies were conducted by LF-NMR and related to beads formulation and lycopene stability. In the absence of excipients, lycopene was severely affected by all the treatments, retaining less than 20% of the original content. Alginate beads containing trehalose with guar gum protected more than 80% of the lycopene regardless of the employed freezing or drying methods. These beads concomitantly showed higher solid fraction than the other two galactomannans-containing systems, displaying guar gum ability to associate water. On the other hand, the addition of vinal gum affected lycopene stability (between 40 and 60% were recovered after treatments), even compromising the positive effect of a well-established cryoprotectant as trehalose. Thus, the addition of secondary excipients should be carefully conducted. The differences among galactomannans could be related to the substitution degree of the polymer chains, affecting the overall systems interactions. These results can contribute to excipients selection for the encapsulation of labile biomolecules in Ca(II)-alginate beads subjected to freezing and drying.

Biopolymeric pellets of polyvinyl alcohol and alginate for the encapsulation of Ib-M6 peptide and its antimicrobial activity against E. coli.

The encapsulation of Ib-M6 antibacterial peptide in pellets of polyvinyl alcohol (PVA) and polyvinyl alcohol-alginate (PVA-Alg) matrices was carried out in order to explore its controlled release and activity against Escherichia coli K-12. The pellets were obtained by combined ice segregation induced self-assembly (ISISA) and freezing-thawing methods and their microstructure was studied by scanning electron microscopy. Bromothymol blue was used as a model compound to study the transport mechanisms and release from pellets. The results show that there is a significant effect of the total concentration of PVA precursor solutions, the mass ratio of PVA of different molecular weights and the addition of alginate on the microstructure and transport properties of pellets. The antibacterial activity of Ib-M6 against Escherichia coli K-12 was not affected by the encapsulation in PVA pellets. However, the release of Ib-M6 from PVA-Alg pellets was not possible, probably due to the electrostatic interaction of positively charged Ib-M6 and negatively alginate structure. Nonetheless, the controlled release of Ib-M6 from polymeric matrices can be fitting by modifying parameters such as the concentration and type of polymer precursors.

Semisolid culture medium improves mycelial recovery of Agaricus subrufescens cryopreserved in cereal grains.

This study aimed to evaluate the effects of the solid and semisolid culture medium on the mycelial viability of A. subrufescens after 5-year cryopreservation at - 70 °C. Mycelia were grown in three types of whole or ground grains, with or without 5% glycerol addition in the substrate and/or in a cryotube. After 5 years of cryopreservation at - 70 °C, every treatment was thawed and recovered in malt extract culture medium with 15 (solid culture medium) or 5 g L-1 (semisolid culture medium) of agar. The semisolid recovery culture medium increased the mycelial viability recovery capacity of A. subrufescens cryopreserved for 5 years in grains with glycerol only in the cryotube, and specifically with medium-hard wheat grain without glycerol addition at all. Agar-based substrates such as malt extract agar, agar-ground grain, or the one with glycerol addition to the substrate were not effective to keep the mycelial viability, regardless of the recovery culture medium consistency. Hard and medium-hard endosperm wheat grains or hard endosperm rye grains with addition of glycerol as cryoprotectant only to the cryotube were effective to cryopreserve the fungus for 5 years without cryoprotectant addition in the substrate.

Effect of low frequency ultrasound thawing method on the quality characteristics of Peru squid ( Dosidicus gigas).

The effects of different thawing methods (air thawing, water soak thawing, refrigeration thawing, low frequency ultrasound thawing at 160, 240, 320 and 400 W) on thawing time, thawing loss, cooking loss, water-holding capacity and texture of frozen squid were investigated. The results showed that thawing loss and thawing time were reduced significantly ( p < 0.05) by ultrasound thawing compared with the water soak thawing and air thawing, but the cooking loss had no significant difference ( p > 0.05). Results of the ultrasound thawing especially at 160 and 240 W on microstructure showed less destructive effect on muscle. The microstructure of the muscle was destroyed significantly after air thawing and water soak thawing compared with the ultrasound thawing, which showed that more fibre structure was broken and the gap between the muscle fibres was increased significantly. Low-field NMR results showed that the ability of immobile water shifting to free water after ultrasound thawing was lower than air thawing and water soak thawing, which was consistent with the results of thawing loss and cooking loss. Ultrasound thawing might be chosen as an alternative method to enhance the quality during thawing process.