Freeze-dried Samples Research Articles

Glass transition temperatures and crystallization kinetics of a synthetic, anhydrous, amorphous calcium-magnesium carbonate.

We report the first calorimetric observations of glass transition temperatures and crystallization rates of anhydrous, amorphous calcium-magnesium carbonate using fast scanning differential scanning calorimetry. Hydrous amorphous Ca0.95Mg0.05CO3 · 0.5H2O (ACMC) solid was precipitated from a MgCl2-NaHCO3 buffered solution, separated from the supernatant, and freeze-dried. An aliquot of the freeze-dried samples was additionally dried at 250°C for up to 6 h in a furnace and in a high-purity N2 atmosphere to produce anhydrous ACMC. The glass transition temperature of the anhydrous Ca0.95Mg0.05CO3 was determined by applying different heating rates (1000-6000 K s-1) and correcting for thermal lag to be 376°C and the relaxational heat capacity was determined to be Cp = 0.16 J/(g K). Additionally, the heating rate dependence of the temperature that is associated with the corrected crystallization peaks is used to determine the activation energy of crystallization to be 275 kJ mol-1. A high-resolution transmission electron microscopy study on the hydrous and anhydrous samples provided further constraints on their compositional and structural states. This article is part of the theme issue 'Exploring the length scales, timescales and chemistry of challenging materials (Part 1)'.

Effect of thin layer drying conditions on the retention of bioactive components in Malabar spinach (Basella alba) leaves

Malabar spinach (Basella alba) is an underexploited tropical leafy vegetable with high nutritional value and therapeutic properties. The leaves are rich in polyphenols, flavonoids, and antioxidants. Identifying appropriate drying methods and conditions for B. alba leaf production and storage can stimulate large-scale manufacture while preserving its intrinsic bioactive components. In this study, an investigation has been carried out to study the impact of thin-layer drying conditions on the retention of bioactive components in B. alba leaves. Drying tests were performed in a hot air oven (50, 60, 70 °C), microwave (600, 650, 700, 750,800 W), and freeze dryer (freezing temperature: -35 °C and vacuum pressure:150 mbar). The drying characteristics of the leaves were investigated. Semi-empirical thin-layer drying models were fitted to the obtained data with the intent to predict the drying behaviour of leaves. Amongst the fitted models, Page and Aghbashlo models showed the best performance with a high R2 value (0.98 – 0.99). The total drying time taken for microwave drying was 98.25% less than the hot air oven drying and 99.19% less than freeze drying. Maximum retention of total phenolic (4.80 ± 0.12 mg GAE g−1) and total flavonoid (5.95 ± 0.02 mg GAE g−1) compounds was observed in freeze-dried samples. Microwave dried samples showed high antioxidant activity than other samples due to less processing time. Results also revealed a less activation energy of 2.22 kJ mol−1 for microwave drying with high moisture diffusivity (1.54 × 10–9 to 4.09 × 10–9 m2s−1).

Drying treatment impact on oil yield extracted from black soldier fly larvae using supercritical carbon dioxide and its biological activities

Abstract Black soldier fly (Hermetia illucens) larvae are considered economically viable as an alternative source of oil and bioactive compounds. The drying and extraction methods are critical steps in the extraction of oil and have an impact on the characteristics and composition of the extracted oil. Supercritical CO2 extraction of oil from black soldier fly larvae allows for the extraction of important bioactive compounds and oils while causing the least amount of change. The effect of different pre-treatment tray-drying and freeze-drying methods on the quantity and biological activities of oil extracted from black soldier fly larvae using supercritical CO2 was investigated in this study. Oil extraction from tray-dried and freeze-dried black soldier fly larvae samples could be done at low temperatures for a shorter extraction time, resulting in higher yields while avoiding the negative effects of high temperatures on lipids and other valuable components. The oil extracted from tray-dried and freeze-dried black soldier fly larvae contained major fatty acid compositions such as lauric acid, linoleic acid, oleic acid and palmitic acid, as well as total phenolic compounds (0.067-0.113 mg gallic acid/g oil), antioxidant capacity 2,2-diphenyl-1-picrylhdrazyl (DPPH) (0.36-0.56 μmol Trolox equivalent antioxidant capacity (TEAC)/10 g oil), and antioxidant capacity 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) (0.23-0.55 μmol TEAC/10 g oil, and ferric reducing antioxidant power antioxidant capacity (0.33-0.64 μmol TEAC/10 g oil). The oil extracted from tray-dried and freeze-dried larvae samples had a shelf life of approximately 2.42-3.63 months and 2.51-3.40 months, respectively, at storage temperatures ranging from 25 to 55 °C. The oil extracted from tray-dried and freeze-dried larvae samples extracted using supercritical CO2 had high acid values which could inhibit keratinocyte growth by 76.70 and 75.04%, respectively, at 100 mg/ml concentrations. Furthermore, the tray-drying and freeze-drying methods had no effect on the physicochemical properties of the supercritical CO2-extracted oil from dried black soldier fly larvae samples.

Impact of Air- and Freeze-Drying Methods on Total Phenolic Content and Antioxidant Activity of Fistulina antarctica and Ramaria patagonica Fructification

Fistulina antarctica and Ramaria patagonica are wild edible fungi from Patagonia, which produce mushrooms that have been consumed since ancient times by those in local communities. Both species possess high protein and low fat contents and other bioactive compounds with remarkable antioxidant activity. Drying is a widely and commonly practiced preservation technique that is cost-effective. However, the process of drying can have an impact on the levels of bioactive compounds. In this study, the effects of drying methods on the total phenolic content (TPC) and antioxidant activity in the fructification of F. antarctica and R. patagonica were estimated. The analysis was conducted using fructifications that were fresh-frozen, dried at 50, 60, and 70 °C, and freeze-dried. The TPC was significantly higher for the fructifications that were fresh-frozen and dried at 60 °C in R. patagonica (with values of 14.78 and 13.67 mg GAE/mg of extract, respectively). Also, the fresh-freezing, freeze-drying. and 60 °C methods exhibited the highest inhibition of free radicals. In addition, R. patagonica had a notably higher concentration of phenols and showed higher antioxidant capacity than F. antarctica. The greatest losses concerning phenols occur in F. antarctica in the three evaluated air-drying temperatures (36.57, 29.76, 39.47% in 50, 60 and 70 °C respectively, compared with fresh-frozen). TPC and antioxidant activity were higher in fresh-frozen and freeze-dried samples. A drying temperature of 60 °C is advisable for both species, considering drying time and bioactivity. Overall, the fructifications from different processing methods exhibited unique functional properties. This information can be utilized to optimize the postharvest preservation and maximize the potential applications of these mushrooms.

Molar masses and molar mass distributions of commercial regenerated cellulose materials and softwood dissolving pulp determined by SEC/MALLS

The molar masses and molar mass distributions of three commercial regenerated cellulose samples, viscose rayon, Tencel, and Bemliese (or cuprammonium nonwoven), have been determined by dissolution in 8% (w/w) lithium chloride/N,N-dimethylacetamide (LiCl/DMAc) and subsequent size-exclusion chromatography with multi-angle laser-light scattering detection (SEC/MALLS). Before dissolution in LiCl/DMAc, the regenerated cellulose samples were pretreated by the following three methods: (1) soaking in ethylene diamine (EDA) and subsequent solvent exchange to N,N-dimethylacetamide (DMAc) through methanol, (2) soaking in water and subsequent solvent exchange to DMAc through ethanol, and (3) soaking in water and subsequent solvent exchange to tert-butyl alcohol through ethanol and freeze dying. The pretreated samples were dissolved in 8% (w/w) LiCl/DMAc by stirring the cellulose/LiCl/DMAc mixtures for 1–3 weeks followed by dilution to 1% (w/v) LiCl/DMAc for SEC/MALLS analysis. The EDA- and water-pretreated samples gave almost the same SEC-elution pattens and molar mass plots, resulting in similar number- and mass-average molar masses. However, the freeze-dried samples gave 10%‒20% lower mass recovery ratios than those obtained for the EDA- or water-pretreated samples, probably because of incomplete dissolution of the freeze-dried samples in 8% (w/w) LiCl/DMAc. The average mass-average degree of polymerization values of viscose rayon, Tencel, and Bemliese were 340, 530, and 880, respectively. The slopes of the conformation plots were 0.58–0.62, showing that all of the molecules in the three regenerated cellulose samples were dissolved in 1% (w/v) LiCl/DMAc, forming linear random-coil conformations.Graphical abstract

Au-NP-based colorimetric assay for sugar detection and quantification

Sugars have been associated with health problems such as metabolic syndrome, obesity, elevated triglycerides, and other features of metabolic disorders. Here, we report on the design and characterization of a highly sensitive gold nanoparticle (AuNP)-based assay for measuring sugars levels in fluids. AuNPs are functionalized with 4-mercaptobenzoic acid (4MBA) to modulate surface plasmonic resonance (SPR) frequency and fluorescent energy absorption by AuNPs, based on a fixed concentration of fluorescein introduced along with a fluid sample containing a determined quantity of sugar. We find the driving mechanism to be kinetic competition between fluorescein and saccharide which occupies the active carboxylic sites of the functional groups on the nanoparticle surface. This drives a colorimetric response in the 4MBA-AuNP solution, from orange to green, discernible to the naked eye. The aggregation of functionalized AuNPs as a result of increasing sugar concentration was confirmed via UV–vis spectroscopy and identified by a spectral peak of 620–675 nm. The limit of detection (LOD) was (55.8 ± 1.1) µM, with a highly repeatable calibration curve in the range of 0.09 – 2.45 mM. The assay's cost-effectiveness, speed, and simplicity open the door to multiple applications associated with detecting and quantifying sugars, including food science. The sensory platform was successfully tested in mixed sugar solutions to study the sensitivity capacity and applied to strawberry and kiwi freeze-dried samples. The results are validated by HPLC with refractive index detection.

Sequential extraction of value-added bioproducts from three Chlorella strains using a drying-based combined disruption technique

In this study, the sequential extraction of the three types of biochemicals from microalgae is employed, which is a more realistic and practical solution for large-scale extraction of bioproducts. The drying, grinding, organic solvent treatment, and ultra-sonication were combined to disrupt cells and sequentially extract bioproducts from three microalgae strains, Chlorella sorokiniana IG-W-96, Chlorella sp. PG-96, and Chlorella vulgaris IG-R-96. As the drying is the most energy-intensive step in cell disruption and sequential extraction, the effect of this step on sequential extraction deeply explored. The results show that total ash-plus contents of biochemicals in freeze-dried samples (95.4 ± 2.8%, 89.3 ± 3.9%, and 77.5 ± 4.2 respectively) are higher than those in oven-dried samples (91.0 ± 2.8%, 89.5 ± 3.0%, 71.4 ± 4.8%, respectively) showing the superiority of freeze drying over oven drying merely for Chlorella vulgaris IG-R-96 (p-value = 0.003) and non-significant variation for Chlorella sorokiniana IG-W-96 (p-value = 0.085) and Chlorella sp. PG-96 (p-value = 0.466). Variation among biochemical contents of strains is due to the difference in cell wall strength confirmed by TEM imaging. The freeze-dried samples achieved higher lipid yields than oven-dried samples. The total carbohydrate yields followed the same pattern. The extraction yields of total protein were higher in freeze-dried samples than in oven-dried. Total mass balance revealed that drying-based sequential extraction of value-added bioproducts could better demonstrate the economic potential of sustainable and renewable algal feedstock than independent assays for each biochemical.Graphical

Effect of freezing and freeze-drying on bioactive compounds and antioxidant activity of carnauba pulp (Copernicia prunifera (Mill.) H.E. Moore)

Carnauba (Copernicia prunifera (Mill.) H.E. Moore) is a fruit of the Brazilian Caatinga and Cerrado regions. It has good nutritional characteristics, bioactive compounds, and antioxidant activity. However, some processing techniques can affect its chemical characteristics. This study aims at evaluating the effect of freezing and freeze-drying on the bioactive compounds and antioxidant activity of carnauba pulp. The carnauba pulp was submitted to three different treatments: slow freezing (-18 °C/24h), fast freezing (-92 °C/60s) and freeze-drying. Then the bioactive compounds of fresh samples were analyzed - vitamin C, phenolics, flavonoids, anthocyanins, carotenoids - along with the antioxidant activity (DPPH), immediately after processing and after 180 days of freezing storage. It was observed that the process influences the behavior of bioactive compounds and antioxidants, with significant losses of vitamin C, anthocyanins, and carotenoids in all treatments soon after processing, while total phenolic compounds, flavonoids and antioxidant activity increased significantly. At the end of 180 days a reduction of all bioactive compounds and antioxidant activity was observed although the freeze-dried samples presented a better stability of the compounds. Thus, quick freezing and freeze-drying could be representing the more promising technological processes for the maintenance of bioactive compounds and antioxidant activity of carnauba pulp.

Effect of drying methods on physicochemical quality of dehydrated jackfruit bulbs

Jackfruit bulbs are regarded as an edible portion and have been shown to contain significant amounts of nutrients such as vitamins, minerals, phytochemicals, carbohydrates, and proteins. The goal of the current research was to find out the effect of drying methods on the physicochemical quality of jackfruit bulbs. The study was done by freeze-drying (FD), cabinet drying (CD), and vacuum drying (VD) for checking the effect of nutritional, physico-chemical, and physical attributes after drying. The phytochemical contents and antioxidant properties of the bulb were analyzed by spectrophotometer and DPPH method respectively. A good amount of carbohydrate content was found in all drying methods, it ranged from 81% to 82%. The total phenolic content (TPC) of FD, CD, and VD dried bulbs was 4.13 ± 0.25 mg, 3.40 ± 0.43 mg and 2.93 ± 0.15 mg GAE/g of dry samples, respectively. Total flavonoid content (TFC) was in the range of 23.52 ± 0.92 mg (FD), 20.30 ± 0.62 mg (CD), and 20.41 ± 0.65 mg (VD) mg QE/100 g of dry samples, whereas the total carotenoid content was 5.60 ± 0.35 mg (FD), 3.61 ± 0.16 mg (CD), and 3.74 ± 0.15 mg (VD) ß-carotene/100 g of dry samples. The antioxidant activity of extracts was 220.22, 194.23, and 131.64 µmole AA/g found in FD, CD, and VD dry samples, respectively. The drying temperatures were revealed to affect characteristics, whereas phytochemical properties, color, texture, rehydration properties, hardness, crispness, and sensory properties gave favorable scores in freeze-dried samples.

Fiber Enrichment of 3D Printed Apricot Gel Snacks with Orange By-Products.

Concern about food waste has become a major global concern. The waste generated by the agri-food industry poses an environmental challenge. However, the development of 3D printing technology offers an opportunity to address this problem. By incorporating food waste into inks, it can create personalized food tailored to individual needs. The aim of this study is the valorization of orange by-products (OBP) in 3D printed gels to obtain a final product in the form of a fiber-enriched snack. Gelatin gels were printed with different concentrations of apricot pulp (30, 50, and 70%) and OBP was added. These gels were subjected to a freeze-drying process. The rheology of the gels before and after printing, the printing precision, and the post-treatment of the freeze-dried product, including color, shear force, and the presence of bioactive compounds, were evaluated. The addition of OBP resulted in an increase in the elasticity (997-1242u) of the samples and improved the printability of them. However, an increase in the hardness (173-184u) was observed in the freeze-dried samples. The use of OBP not only improves the printability of the gels but also enables obtaining fiber-enriched snacks, which could contribute to the reduction in food waste and the promotion of healthy and sustainable food.

Under-utilized wild fruit Lepisanthes rubiginosa (Roxb.) Leenh: A discovery of novel lycopene and anthocyanin source and bioactive compound profile changes associated with drying conditions

Lepisanthes rubiginosa (Roxb.) Leenh (LRL), a wild fruit of Thailand, was characterized for phytochemicals including phenolic acids, flavonoids, carotenoids, anthocyanins, organic acids, and sugars. To process it, three drying methods were investigated, namely, freeze drying (FD), hot-air drying (HD), and sun drying (SD), which affected chemical components and antioxidant activities. The predominant phenolic acids and flavonoids were p-hydroxybenzoic acid, chlorogenic acid, vanillic acid, quercetin, rutin, and myricetin. Remarkably high amounts of lycopene (158 mg/100g db) and cyanidin-3-O-glucoside (2005 mg/100g db) were observed. Flavonoids, carotenoids, and anthocyanin were decreased by all drying methods. Overall, FD was considered to be the most suitable for drying LRL fruit. Fructose conversion to mannitol during drying was explored by FTIR spectroscopy analysis in FD and HD samples. This study has revealed new information about LRL fruits, which could be a potential source of bioactive compounds; an appropriate drying method is suggested for further applications.

Elucidation of flavanones, phenols and antioxidant capacity influenced by drying methods from physiologically dropped underutilized Citrus grandis fruits.

Nutritional content in citrus fruit is enormous. Citrus grandis (L.) Osbeck is underutilised citrus crop that receives little attention due to the lack of knowledge regarding its nutritional value. Citrus waste disposal poses a problem due to economic and environmental factors. The metabolites flavonoids, phenols and antioxidant capacity in the dropped fruits of the underutilised citrus species pomelo (Citrus grandis (L.) Osbeck) were examined. Hesperidin varied from 1.22 to 2.83% and 1.08 to 1.16% from 10 mm to 14 mm whereas naringin dominates in fruits measuring 10 mm and 12mm with 60.61%, 60.77%, and 47.76%, 45.87% in freeze dried (FD) and hot air oven dried (HAOD) samples. According to the results of the antioxidant assays, the highest concentrations of ABTS azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) and DPPH (2, 2-diphenyl-1-picrylhydrazyl radical) were found in freeze dried samples, ranging from 9.679 to 10.416 mmol L-1 Trolox and 14.825 to 16.432 mmol L-1 Trolox, respectively. However, the Ferric Reducing Antioxidant Power (FRAP) assay revealed higher content in samples of both FD and HAOD that were 10mm in size (4.578 mmol L-1 Trolox and 3.730 mmol L-1 Trolox). Total phenol content was measured, and the highest concentrations were found in fruits with a diameter between 10 mm and 18 mm. It ranged from 48.479 to 54.498 mg GAE L-1 in FD samples and from 45.757 to 51.159 mg GAE L-1 in HAOD samples. The smallest fruits, or those that were still in the immature stage, had the highest content. It was found that when the immature dropped fruits were dried by HAOD, the content decreased. At p<0.01 and p<0.05, there was a significant positive correlation between the flavonoids, antioxidants, and total phenols. The results showed that the immature dropped immature fruits of lesser known underutilised citrus sp. Citrus grandis can act as potential source of flavonoids, total phenol concentration, and antioxidant potential. Freeze drying can be recommended to recover the most bioactive substances from physiologically dropped fruits of Citrus grandis for use in the pharmaceutical and nutraceutical sectors. This study will help in reducing the environmental impact caused due to citrus dropped fruits and its responsible management.

BOX-BEHNKEN DESIGN-BASED DEVELOPMENT AND CHARACTERIZATION OF POLYMERIC FREEZE-DRIED NANOPARTICLES OF ISRADIPINE FOR IMPROVED ORAL BIOAVAILABILITY

Objective: This study aimed to develop and optimize isradipine-loaded polymeric freeze-dried nanoparticles prepared by solvent shifting method with the help of the experiment design for improving oral drug bioavailability and minimizing dosing intervals. Methods: Isradipine is a potent anti-hypertensive drug that is matrixed in polymeric freeze-dried nanoparticles using solvent shifting. In this work, a 3-factor, 3-level box-Behnken design was used to optimize the process parameters like a drug: PLA concentration (A), poloxamer 407 concentration (B), and stirring speed (C). In addition, responses were measured as dependent variables such as percentage drug release, particle size (nm), Zeta potential (mV), and % entrapment efficiency. Results: Mathematical equations and response surface plots were used to relate the dependent and independent variables. The optimization model exhibited 97.36 % drug release, 153.14 nm particle size,-25.9 mV Zeta potential, and 78.25% entrapment efficiency, respectively. The observed responses were in close agreement with the predicted values of the optimized process. Fourier transform infrared spectroscopy, morphological studies, and in vitro drug release studies characterized the prepared polymeric nanoparticles. Conclusion: The improved freeze-dried polymeric nanoparticle samples exhibited an in vitro drug release rate of more than 90% at 24h. Based on in vivo pharmacokinetic parameters, the isradipine-loaded polymeric nanoparticles show better bioavailability than pure drug's suspension form.

Diagnosis and monitoring of hepatocellular carcinoma in Hepatitis C virus patients using attenuated total reflection Fourier transform infrared spectroscopy

BackgroundCurrent diagnostic methods for assessment of hepatitis C virus related hepatocellular carcinoma and subsequent categorization of hepatocellular carcinoma into non-angio-invasive hepatocellular carcinoma and angio-invasive hepatocellular carcinoma, to establish appropriate treatment strategies, are costly, invasive and requires multiple screening steps. This demands alternative diagnostic approaches that are cost-effective, time-efficient, and minimally invasive, while maintaining their efficacy for screening of hepatitis c virus related hepatocellular carcinoma. In this study, we propose that attenuated total reflection Fourier transform infrared in conjunction with principal component analysis – linear discriminant analysis and support vector machine multivariate algorithms holds a potential as a sensitive tool for the detection of hepatitis C virus-related hepatocellular carcinoma and the subsequent categorization of hepatocellular carcinoma into non-angio-invasive hepatocellular carcinoma and angio-invasive hepatocellular carcinoma. MethodsFreeze-dried sera samples collected from 31 hepatitis c virus related hepatocellular carcinoma patients and 30 healthy individuals, were used to acquire mid-infrared absorbance spectra (3500–900 cm-1) using attenuated total reflection Fourier transform infrared. Chemometric machine learning techniques were utilized to build principal component analysis – linear discriminant analysis and support vector machine discriminant models for the spectral data of hepatocellular carcinoma patients and healthy individuals. Sensitivity, specificity, and external validation on blind samples were calculated. ResultsMajor variations were observed in the two spectral regions i.e., 3500–2800 and 1800–900 cm-1. IR spectral signatures of hepatocellular carcinoma were reliably different from healthy individuals. Principal component analysis – linear discriminant analysis and support vector machine models computed 100% accuracy for diagnosing hepatocellular carcinoma. To classify the non-angio-invasive hepatocellular carcinoma/ angio-invasive hepatocellular carcinoma status, diagnostic accuracy of 86.21% was achieved for principal component analysis – linear discriminant analysis. While the support vector machine showed a training accuracy of 98.28% and a cross-validation accuracy of 82.75%. External validation for support vector machine based classification observed 100% sensitivity and specificity for accurately classifying the freeze-dried sera samples for all categories. ConclusionsWe present the specific spectral signatures for non-angio-invasive hepatocellular carcinoma and angio-invasive hepatocellular carcinoma, which were prominently differentiated from healthy individuals. This study provides an initial insight into the potential of attenuated total reflection Fourier transform infrared to diagnose hepatitis C virus related hepatocellular carcinoma but also to further categorize into non-angio-invasive and angio-invasive hepatocellular carcinoma.

Elite cassava clones (Manihot esculenta) grown in Zambia: effects of drying techniques on their chemical, functional, and pasting properties

IntroductionCassava (Manihot esculanta) is becoming an important crop in most developing countries, especially Zambia. However, cassava roots deteriorate quickly after harvest, producing flour or chips of sub-optimal quality. Hence the evaluation of processing procedures to extend the product's shelf-life cannot be overemphasized. This study investigated the effects of different drying methods on the chemical, functional and pasting properties of selected advanced cassava clones grown in Zambia.MethodsFresh Roots of the seven cassava clones (harvested 12 months after planting) were sampled, peeled, washed and dried using the three drying methods (sun-drying, oven-drying and freeze-drying). The flour samples from these drying methods were analyzed using standard laboratory methods for primary chemical, functional and pasting properties. The data generated were statistically analyzed for descriptive, analysis of variance (ANOVA), and the means were separated at p &amp;lt; 0.05.Results and discussionThe clone and drying method had significant effects (p &amp;lt; 0.001) on most chemical, functional and pasting properties. Clone 00/0093 had consistently lower ΔE* values for each drying method than other clones. The overall mean of total color difference (ΔE*) across the genotypes revealed the ranking ΔE* for drying techniques in the order of oven &amp;gt; sun &amp;gt; freeze drying. Generally, the highest sugar content was recorded for the freeze-dried samples. Similarly, the total starch content was higher in the sun-dried samples of six out of the seven samples than in the oven-dried samples. The functional properties ranged from 31.29–61.04%, 2.31–5.41%, 119.68–206.78% and 54–70 for solubility, swelling power, water absorption capacity and dispersibility, respectively.ConclusionIn conclusion, the clonal effect of the cassava and drying method significantly affected the cassava flours' color, chemical, functional, and pasting properties.

Fruit and vegetable purees as cryoprotectants for vacuum freeze-dried fermented milk products

Fresh fermented milk products have a limited shelf life that can be extended by vacuum freeze-drying. Cryoprotectants are used to increase the survival of lactic acid microorganisms during freeze-drying. The most effective cryoprotectants are those of natural origin. Literature offers little information on the cryoprotective effects of fruit and vegetable purees. Therefore, we aimed to evaluate the effectiveness of fruit and vegetable purees in increasing the survival of lactic acid microorganisms during the freeze-drying and storage of fermented milk products. &#x0D; We studied bioyogurt samples containing pumpkin, fig, and banana purees. Rational modes of freezing and freeze-drying were established on the basis of thermal analysis. The cryoscopic temperature was determined by differential scanning calorimetry. The proportion of frozen moisture was calculated using the Nagaoka formula. Standard methods were employed to evaluate the sensory characteristics of bioyogurts and determine their protein, fat, and non-fat milk solids contents, as well as titratable acidity and microbiological indicators. &#x0D; The addition of pumpkin puree increased the cryoscopic temperature and reduced the freeze-drying stage and the total drying time by 13 h, depending on the amount of puree. However, the addition of sweet fig and banana purees decreased the cryoscopic temperature and increased the freeze-drying stage and the total drying time by 0.5–1.5 and 1.5–3 h, respectively. Based on the sensory evaluation of the freeze-dried bioyogurts, we selected the formulations with 15% of pumpkin and fig purees and 10% of banana puree. We found that the freeze-dried bioyogurts with puree had higher counts of lactic acid bacteria compared to the control. In the freeze-dried samples, the counts were higher at a storage temperature of 4 ± 2°C than at 20 ± 2°C. &#x0D; Pumpkin puree provided the best survival of lactic acid microorganisms during freeze-drying and storage.

Characteristic fingerprints and comparison of volatile flavor compounds in Morchella sextelata under different drying methods

Morchella sextelata is a precious and popular commercial edible fungus that was developed recently in China. This research aimed to characterize the volatile profiles of M. sextelata under three dehydration methods (freeze, hot air, and natural air drying). Comprehensive two-dimensional gas chromatography–time-of-flight mass spectrometry (GC × GC-ToF-MS) was shown to the best choice to discriminate the volatile profiles of M. sextelata Characteristic flavor substances of M. sextelata were eight-carbon-containing (C8) compounds, hexanal, 2(5 h)-furanone, and benzaldehyde. Drying methods had significant influences on the volatile flavor profiles of M. sextelata, and 104 differential compounds were screened by multivariate statistical analysis. Freeze-dried samples had the most abundant volatile compounds and maintained more alcohols, ketones, aldehydes, and esters described as mushroom, sweet, and green flavor, like 1-octen-3-ol, 1-octen-3-one, nonanal, 2,3-butanedione, and so on. Hot air-drying promoted the production of heterocycles and ketones with roasted flavor due to the thermalreaction, such as 2-cyclohexen-1-one, furan, 3-phenyl-, etc. Natural air-drying resulted in acids releasing an unpleasant flavor, e.g., acetic acid, 2-methylbutanoic acid, etc. Overall, thermal reaction combined with vacuum conditions might be suitable for maintaining and enriching the aroma flavor of dried true morels.

Effects of vacuum microwave combined with freeze-drying on the physicochemical properties, phenolic compounds, and antioxidant capacity of pear fruit slices.

The effects of freeze-drying (FD), vacuum microwave drying after freeze-drying (FD-VMD), and freeze-drying after vacuum microwave drying (VMD-FD) on the physicochemical properties, phenolic compounds, and antioxidant capacity of pear fruit slices were investigated. The results showed that FD samples had the highest crispness value (116.30 N·sec) and the lowest volume shrinkage ratio value (5.48%). Compared to FD, the VMD-FD and FD-VMD methods could save drying time without affecting the color of dried samples. FD-VMD samples had the lowest rehydration capacity and maintained a homogeneous porous structure, while the VMD-FD samples had obvious collapse. Compared to VMD-FD samples, FD-VMD samples had higher contents of ascorbic acid (20.91 mg/100 g), total phenolic (7.62 mg/g), total anthocyanin (0.21 mg/g), and gallic acid (1.21 µg/g). Moreover, FD-VMD samples showed the highest antioxidant capacity as evaluated by the 2,2-diphenyl-1-(2,4,6-trinitrophenyl) hydrazyl scavenging activity, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) scavenging capacity, and H2 O2 content. Compared with FD and VMD-FD, FD-VMD was most effective in maintaining better quality and shortening drying time of pear fruit slices. These findings suggested that FD-VMD might be a promising drying technique in the fruits and vegetable processing industries.

Content of luteolin and luteolin-7-О-glucoside from the leaves of Vernonia amygdalina Del., and synergistic inhibitory effect with cisplatin on nasopharyngeal carcinoma cells

This study describes the quantification of luteolin and luteolin-7-О-glucoside in methanol leaf extract of Vernonia amygdalina by HPLC method. Dried powdered leaves were extracted with methanol at 40 °C for 6 h and freeze-dried. The freeze-dried sample was then analyzed by HPLC. The content of luteolin was lesser than luteolin-7-O-glucoside in the extract. The extract and the bioactive compounds were screened for inhibitory effects on nasopharyngeal carcinoma cells. Flow-cytometry and high content analysis were performed to detect luteolin-induced apoptosis. The effects of combining luteolin and cisplatin on cultured cells were explored. Luteolin produced a dose-dependent inhibition of all cell lines tested. Flow cytometry analysis revealed that luteolin did not induce apoptosis. Simultaneous combinations of luteolin and cisplatin produced synergistic effects, suggesting that the dosage of cisplatin required to treat NPC could be reduced with the addition of luteolin; sequentially lessening the risk of cisplatin-associated toxicity.

Isolation of Bacteria from Freeze-Dried Samples and the Functional Characterization of Species-Specific Lactic Acid Bacteria with a Comparison of Wild and Captive Proboscis Monkeys.

Previously, we isolated a novel lactic acid bacteria species (Lactobacillus nasalidis) from the fresh forestomach contents of a captive proboscis monkey (Nasalis larvatus) in a Japanese zoo. In this study, we isolated two strains of L. nasalidis from the freeze-dried forestomach contents of a wild proboscis monkey inhabiting a riverine forest in Malaysia. The samples had been stored for more than six years. Phenotypic analysis showed that strains isolated from the wild individual had more diverse sugar utilization and lower salt tolerance than strains previously isolated from the captive counterpart. These phenotypic differences are most likely induced by feeding conditions; wild individuals consume a wide variety of natural food, unlike their zoo-raised counterparts that consume formula feed with sodium sufficiency. Since 16s rRNA sequences of L. nasalidis were detected in the previously created 16S rRNA libraries of wild, provisioned, and captive proboscis monkeys in Malaysia and Japan, L. nasalidis may be an essential bacterium of the foregut microbial community of the proboscis monkey. The currently established method for the isolation of gut bacteria from freeze-dried samples under storage will be applicable to many already-stored precious samples.