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1.
Foods ; 13(14)2024 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-39063320

RESUMO

It is important to differentiate milk with different thermostabilities for diverse applications in food products and for the appropriate selection of processing and maintenance of manufacturing facilities. In this review, an overview of the chemical changes in milk subjected to high-temperature heating is given. An emphasis is given to the studies of traditional and state-of-the-art strategies for assessing the milk thermostability, as well as their influencing factors. Traditional subjective and objective techniques have been used extensively in many studies for evaluating thermostability, whereas recent research has been focused on novel approaches with greater objectivity and accuracy, including innovative physical, spectroscopic, and predictive tools.

2.
Sichuan Da Xue Xue Bao Yi Xue Ban ; 55(3): 769-776, 2024 May 20.
Artigo em Chinês | MEDLINE | ID: mdl-38948293

RESUMO

Objective: To experimentally validate the effects of a self-developed heat-stable thickening agent on the textual characteristics of enteral nutrition solutions of standard concentration and its applicability in improving dysphagia. Methods: A gradient of different doses of the self-developed thickening agent (1.0 g, 1.5 g, 2.0 g, 2.5 g, and3.0 g) and three commonly used commercial thickeners were mixed with 23.391 g of a complete nutrition formula powder dissolved in 85 mL of purified water to prepare 100 mL standard concentration nutrition solutions. The textual parameters (cohesiveness, viscosity, thickness, and hardness) of these nutrition solutions were measured using a texture analyzer at various temperature gradients (20 ℃, 40 ℃, 60 ℃, and 80 ℃) to compare their thermal stability. A dysphagia rat model was created via epiglottectomy to explore the effects of the thickener on lung tissue damage scores and levels of inflammatory markers. The rats were divided into a test intervention group, a positive control group, a negative control group, and a blank control group (no surgery and normal feeding after fasting for one day), with 15 rats in each group. After fasting for one day post-surgery, the test intervention group was fed with the standard concentration nutrition solution thickened with the self-developed thickener, while the positive control group was given a standard concentration nutrition solution thickened with product 3, and the negative control group was fed a normal diet. All groups were fed for two weeks with food dyed with food-grade green dye. General conditions, body mass, and food intake were observed and recorded. After two weeks, abdominal aorta blood was collected, and heart, liver, spleen, lung, and kidney tissues were harvested and weighed to calculate the lung tissue organ coefficient. The organ conditions were evaluated using routine H&E staining, and lung damage was semi-quantitatively analyzed based on the Mikawa scoring criteria. Blood supernatants were collected to measure the total serum protein and albumin levels to determine the nutritional status of the rats. The expression of IL-6 and TNF-α genes in lung tissues was measured by RT-qPCR. IL-6 and TNF-α protein expression levels in lung tissues, lung tissue homogenate, and serum were measured by ELISA. The aspiration incidence rate was calculated. Results: Within the dosage range of 1.0 g to 3.0 g, the self-developed thickener in the test samples exhibited superior thermal stability in cohesiveness compared to the three commercially available thickeners, with a statistically significant difference (P<0.01). The differences in the thermal stability of viscosity and hardness between the self-developed thickener and the three commercially available thickeners were not statistically significant. The viscosity stability was optimal for the self-developed thickener, followed by the commercially available thickeners 1 and 3, with thickeners 2 being the least stable, though the differences were not statistically significant (P>0.05). Product 1 showed the best thermal stability in thickness, followed by the self-developed thickener and product 2, while the product 3 exhibited the worst performance, with the difference being statistically significant (P<0.01). The self-developed thickener had the best thermal stability in hardness at temperatures ranging from 20℃ to 80 ℃, followed by products 1 and 2, with product 3 being the least stable. However, the differences were not statistically significant (P>0.05). Animal experiment results indicated that the body weight gain in the positive control group and the test intervention group was lower than that in the blank and negative control groups (P<0.01). The spleen coefficient of the intervention group was lower than that of the positive control group and the blank control group (P<0.01), while the heart, liver, and kidney coefficients were lower than those of the blank control group (P<0.01). The differences in the lung coefficient of the intervention group and those of the other three groups were no statistically significant. Levels of TP and ALB in the test intervention group, the positive control group, and the negative control group were all lower than those in the blank control group, with statistically significant differences (P<0.01). ELISA results showed that serum IL-6 levels in the blank and test intervention groups were lower than those in the negative and positive control groups (P<0.05), while the difference in the other indicators across the four groups were not statistically significant (P>0.05). There were no statistically significant differences among the four groups in terms of lung tissue damage pathology scores, or in the levels of IL-6 and TNF-α gene expression in lung tissues. The aspiration incidence rate was 0% in all groups. Conclusion: The self-developed enteral nutrition thickening agent demonstrated excellent thermal stability and swallowing safety. Further research to explore its application in patients with dysphagia is warranted.


Assuntos
Transtornos de Deglutição , Nutrição Enteral , Animais , Ratos , Transtornos de Deglutição/etiologia , Nutrição Enteral/métodos , Ratos Sprague-Dawley , Deglutição/fisiologia , Masculino , Pulmão/fisiologia , Temperatura Alta , Viscosidade
3.
Small Methods ; : e2400241, 2024 Apr 21.
Artigo em Inglês | MEDLINE | ID: mdl-38644347

RESUMO

All-inorganic lead halide perovskite nanocrystals (NCs) have been widely applied in optoelectronic devices owing to their excellent photoluminescence (PL) properties. However, poor stability upon exposure to water, UV light or heat strongly limits their practical application. Herein, CsPbBr3@Pb-MOF composites with exceptional stability against water, UV light, and heat are synthesized by ultrasonic processing the precursors of lead-based MOF (Pb-MOF), oleylammonium bromide (OAmBr) and cesium oleate (Cs-OA) solutions at room temperature. Pb-MOF can not only provide the lead source for the in situ growth of CsPbBr3 NCs, but also the protective layer of perovskites NCs. The formed CsPbBr3@Pb-MOF composites show a considerable PL quantum yield (PLQY) of 67.8%, and can maintain 90% of the initial PL intensity when immersed in water for 2 months. In addition, the outstanding PL stability against UV light and heat is demonstrated with CsPbBr3 NCs synthesized by the conventional method as a comparison. Finally, a green (light-emitting diode) LED is fabricated using green-emitting CsPbBr3@Pb-MOF composites and exhibits excellent stability without packaging when immersed in water for 30 days. This study provides a practical approach to improve the stability in aqueous phase, which may pave the way for future applications for various optoelectronic devices.

4.
Foods ; 13(6)2024 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-38540833

RESUMO

Anthocyanins are prone to degradation and color fading after sterilization. This work examined the potential of wheat protein hydrolysates (WPHs, 40 g/L) in improving the stability of purple sweet potato anthocyanins (PSPAs) under a pH of 6.8 after sterilization at 121 °C followed by storage. Results showed that WPHs increased the thermal degradation half-life of PSPAs 1.65 times after sterilization. Compared to PSPAs alone, after being stored at 37 °C and 45 °C for 7 days, the retention concentration of PSPAs with WPHs was 5.4 and 32.2 times higher, and the color change of PSPAs with WPHs decreased from 6.19 and 10.46 to 0.29 and 0.77, respectively. AFM data, fluorescence and UV spectrograms indicated the formation of complexes between PSPAs and WPHs by hydrophobic attraction confirmed by zeta-potential data. PSPAs with WPHs had stable particle size and zeta potential, which may also significantly increase the concentrations after digestion and antioxidant power of PSPAs. This work indicated that the assembled PSPAs composite structure by WPHs significantly reduced the degradation of PSPAs at a pH of 6.8 after sterilization at 121 °C followed by long-term storage.

5.
Plants (Basel) ; 13(3)2024 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-38337985

RESUMO

Chlorophyll (Chl) fluorescence induction (FI) upon a dark-light transition has been widely analyzed to derive information on initial events of energy conversion and electron transfer in photosystem II (PSII). However, currently, there is no analytical solution to the differential equation of QA reduction kinetics, raising a doubt about the fitting of FI by numerical iteration solution. We derived an analytical solution to fit the OJ phase of FI, thereby yielding estimates of three parameters: the functional absorption cross-section of PSII (σPSII), a probability parameter that describes the connectivity among PSII complexes (p), and the rate coefficient for QA- oxidation (kox). We found that σPSII, p, and kox exhibited dynamic changes during the transition from O to J. We postulated that in high excitation light, some other energy dissipation pathways may vastly outcompete against excitation energy transfer from a closed PSII trap to an open PSII, thereby giving the impression that connectivity seemingly does not exist. We also conducted a case study on the urban heat island effect on the heat stability of PSII using our method and showed that higher-temperature-acclimated leaves had a greater σPSII, lower kox, and a tendency of lower p towards more shade-type characteristics.

6.
Foods ; 13(2)2024 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-38254564

RESUMO

Milk protein concentrates (MPCs) possess significant potential for diverse applications in the food industry. However, their heat stability may be a limitation to achieving optimal functional performance. Shearing, an inherent process in food manufacturing, can also influence the functionality of proteins. The aim of this research was to examine the heat stability of reconstituted MPCs prepared at two protein concentrations (4% and 8% w/w protein) when subjected to varying levels of shearing (100, 1000, or 1500 s-1) during heating at 90 °C for 5 min or 121 °C for 2.6 min. While the impact of shear was relatively minor at 4% protein, it was more pronounced in 8% protein MPC suspensions, leading to a considerable decline in heat stability. An increase in protein concentration to 8% amplified protein interactions, intensified by shearing. This, in turn, resulted in comparatively higher aggregation at elevated temperatures and subsequently reduced the heat stability of the reconstituted MPCs.

7.
J Dairy Sci ; 107(5): 2721-2732, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38101742

RESUMO

Processing temperature has a significant influence on the composition and functionality of the resulting streams following microfiltration (MF) of skim milk. In this study, MF and diafiltration (DF) were performed at 4 or 50°C to produce ß-casein (ß-CN)-depleted and nondepleted (i.e., native casein profile) micellar casein isolate retentates, respectively. Microfiltration combined with extensive DF resulted in a 40% depletion of ß-CN at 4°C, whereas no ß-CN depletion occurred at 50°C. Microfiltration at 4°C led to higher transmission of calcium into permeates, with retentate generated at 4°C containing less total calcium compared with retentate generated at 50°C, based on the volume of retentate remaining. Higher heat stability at 120°C was measured for retentates generated at 4°C compared with those at 50°C, across all pH values measured. Retentates generated at 4°C also had significantly lower ionic calcium values at each pH compared with those generated at 50°C. Higher apparent viscosities at 4°C were measured for retentates generated at 4°C compared with retentates generated at 50°C, likely due to increased voluminosity of ß-CN-depleted casein micelles. The results of this study provide new information on how changing the composition of MF retentate, by appropriate control of processing temperature and DF, can alter physicochemical properties of casein micelles, with potential implications for ingredient functionality.


Assuntos
Caseínas , Micelas , Animais , Caseínas/química , Temperatura , Cálcio/análise , Manipulação de Alimentos/métodos , Filtração/métodos , Filtração/veterinária , Leite/química , Proteínas do Leite/análise
8.
Foods ; 12(24)2023 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-38137208

RESUMO

Milk protein dispersions containing added cocoa powder (1.5% (w/w)) and sucrose (7% (w/w)) and varying levels of κ-carrageenan (0.01, 0.03, or 0.05% w/w) were subjected to combined heat treatment (90 °C/5 min or 121 °C/2.6 min) and shear (100 or 1000 s-1) to investigate the heat stability of milk proteins. The application of shear led to a notable reduction in non-sedimentable proteins, resulting in an increase in the average particle size and apparent viscosity of the dispersions, particularly at high concentrations of k-carrageenan and elevated temperatures. This indicates that shear forces induced prominent protein aggregation, especially at higher κ-carrageenan concentrations. This aggregation was primarily attributed to the destabilisation of micelles and presence of loosely bound caseins within the κ-carrageenan network, which exhibited increased susceptibility to aggregation as collision frequencies increased due to shear.

9.
J Food Sci Technol ; 60(11): 2772-2781, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-37711581

RESUMO

Bread forms an integral part of the daily diet in many cultures worldwide. At the same time, a significant number of people try to avoid wheat-based products for either health reasons or due to personal preferences. The absence of a protein network in gluten free bread affects its structure, taste, texture and shelf-life. This paper suggests a technological solution to this issue that uses a pre-foamed mass of gluten free raw materials which is mixed with the bread's ingredients, then kneaded and baked to form a high quality gluten free bread. To survive the high shear stresses during kneading and temperature increase during baking, the foam requires exceptional stability. This stability was achieved through particle stabilisation of the bubble interfaces. Both of the tested foams (with and without particles) exhibited thermal stability up to 80 °C. However, resistance to shear stresses was higher in the particle stabilised foams. Of all the tested particles, linseed press cake and banana powder led to the best results. In conclusion, particle stabilised foams seem very well suited to applications in gluten free baked goods. Further application potential is seen for vegan foamed desserts.

10.
Food Res Int ; 170: 112924, 2023 08.
Artigo em Inglês | MEDLINE | ID: mdl-37316041

RESUMO

Protein-containing food products are frequently heated during processing to passivate anti-nutritional components. However, heating also contributes to protein aggregation and gelation, which limits its application in protein-based aqueous systems. In this study, heat-stable soy protein particles (SPPs) were fabricated by preheating at 120 °C for 30 min and at 0.5% (w/v) protein concentration. Compared to untreated soy proteins (SPs), SPPs exhibited a higher denaturation ratio, stronger conformational rigidity, compacter colloidal structure, and higher surface charge. The aggregation state of SPs and SPPs at various heating conditions (temperatures, pH, ionic strength, and types) was analyzed by dynamic light scattering, atomic force microscopy, and cryo-scanning electron microscopy. SPPs showed less increase in particle size and greater anti-aggregation ability than SPs. When heated in the presence of salt ions (Na+, Ca2+) or at acidic conditions, both SPs and SPPs formed larger spherical particles, but the size increase rate of SPPs was significantly lower than SPs. These findings provide theoretical information for preparing heat-stable SPPs. Furthermore, the development of SPPs is conducive to designing protein-enriched ingredients for producing innovative foods.


Assuntos
Calefação , Proteínas de Soja , Temperatura , Concentração Osmolar , Concentração de Íons de Hidrogênio
11.
J Dairy Res ; 90(2): 205-212, 2023 May.
Artigo em Inglês | MEDLINE | ID: mdl-37264806

RESUMO

Eggnog, a dairy-based beverage, comprises both milk and egg proteins. We aimed at optimizing the eggnog formulation using Box-Behnken design of response surface methodology. The combined effects of milk (60-75), cream (25-35) and eggnog base (6-8, all three as g 100/ml) were investigated on heat coagulation time, viscosity and thermal gelation temperature. ANOVA indicated that experimental data were well explained by a quadratic model with high check values (R2 > 0.94) and non-significant lack of fit tests. Based on the responses, an optimized formulation of eggnog with 60.0 milk, 25.0 cream and 6.50 eggnog base (as g 100/ml), could be considered best for manufacturing eggnog with desired attributes. This optimized formulation was characterized for physico-chemical, microbial and sensory attributes and the results indicated significantly higher fat and protein content than control formulation, but lesser lactose and total sugar content. Significantly higher viscosity, heat stability and lower thermal gelation temperature were also observed for the optimized formulation. Coliform, yeast and mold, E. coli and Salmonella counts were not detected in any sample but a significantly lower total plate count was observed for the optimized formulation.


Assuntos
Escherichia coli , Leite , Animais , Leite/química , Temperatura , Bebidas/análise , Temperatura Alta
12.
J Dairy Sci ; 106(10): 6741-6758, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37236830

RESUMO

Studies on the storage stability of milk powder are currently fragmented and mainly affect only the area of above-zero temperatures. At the same time, there are no studies that consider the load factor when milk powder is stored in bags on a pallet. The purpose of this study was to identify the influence of various factors of industrial storage (temperature, height or layer number, and time) on the change in quality and technological properties of powdered dairy products. We placed skim milk powder (SMP) and whole milk powder (WMP) in 10 × 14 × 2 cm resealable plastic bags on a model stand simulating an industrial layout on pallets. The samples were stored for 18 mo at temperatures -30 ± 1°C, 6 ± 1°C, and 25 ± 3°C and 40 to 80% relative humidity. Samples from the control (0), 5, and 10 (lower) layers of pallets were selected for analysis on 0, 3, 6, 9, 12, 15, and 18 mo of storage for each of the temperatures. As a result, we did not detect any changes in the storage process for water activity and mass fraction of moisture. The particle size distribution of all the SMP and WMP samples changed over time. The greatest changes were observed in the WMP samples placed on the 10th layer of pallets at 25 ± 3°C, from 0 to 18 mo of storage, the mean particle size (D[4,3]) increased from 120 to 258 µm (90% of all sample particle sizes ranging from 209 to 559 µm). We found significant clumping in the WMP samples (lumps up to 5 cm), correlating with the layer and storage time. The contact angle of the samples increased from 17° (SMP) and 53° (WMP) to 40° and 71°, respectively. The insolubility index and titratable acidity did not change only in the SMP samples stored with no load applied at -30 ± 1°C and 6 ± 1°C. The heat stability of all samples stored at 25 ± 3°C showed the lowest values. The data obtained allowed us to rank the factors as "layer - time - temperature." Only the temperature of 25 ± 3°C caused critical changes in the product properties. Thus, the possibility of industrial storage of the product for up to 15 mo over the entire temperature range is confirmed.


Assuntos
Leite , Água , Animais , Pós , Temperatura
13.
Mol Nutr Food Res ; 67(16): e2200601, 2023 08.
Artigo em Inglês | MEDLINE | ID: mdl-37173826

RESUMO

SCOPE: Red meat, a staple food of Western diets, can also induce IgE-mediated allergic reactions. Yet, apart from the heat-labile protein serum albumin and the carbohydrate α-Gal, the molecules causing allergic reactions to red meat remain unknown. METHODS AND RESULTS: IgE reactivity profiles of beef-sensitized individuals are analyzed by IgE-immunoblotting with protein extracts from raw and cooked beef. Two IgE-reactive proteins are identified by peptide mass fingerprinting as myosinlight chain 1 (MYL1) and myosin light chain 3 (MYL3) in cooked beef extract and are designated Bos d 13 isoallergens. MYL1 and MYL3 are produced recombinantly in Escherichia coli. ELISAs proved their IgE reactivity and circular dichroism analysis showed that they represent folded molecules with remarkable thermal stability. In vitro gastrointestinal digestion experiments showed the higher stability of rMYL1 as compared to rMYL3. Exposure of a monolayer of Caco-2 cells to rMYL1 indicated that the molecule is able to cross intestinal epithelial cells without disturbing the integrity of the tight junctions, suggesting the sensitizing capacity of MYL1. CONCLUSION: MYLs are identified as novel heat-stable bovine meat allergens.


Assuntos
Alérgenos , Hipersensibilidade Alimentar , Humanos , Bovinos , Animais , Hipersensibilidade Alimentar/etiologia , Temperatura Alta , Células CACO-2 , Imunoglobulina E , Carne/análise , Reações Cruzadas
14.
J Sci Food Agric ; 103(11): 5616-5625, 2023 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-37066687

RESUMO

BACKGROUND: Recently, there is a growing interest in developing protein-fortified liquid systems, which are formulated to provide special nutrient combinations to those with special dietary needs. The fabrication of heat-stable protein for protein-fortified liquid systems relies heavily on precise control of the edible protein-building process. RESULTS: Results suggested that heat-stable 7S protein particles (7SPPs) could be obtained by preheating at 100 °C for an extended time, whereas 7S proteins with better gelling properties were discovered after preheating at lower temperatures. According to the findings of the protein conformational and morphological characterization, the 7SPPs showed rather stable tertiary and secondary structures as well as size distributions, which might be responsible for their heat stability. Additionally, during the reheating test, suspensions of 7SPPs showed no signs of gelation and had a low viscosity even though the protein content was as high as 120 mg mL-1 . However, 7S proteins with improved gelling properties were found to show rising aggregate size, higher susceptibility and larger conformational structure changing rates upon reheating treatment. CONCLUSION: Soy ß-conglycinin (7S) proteins with tunable heat stability were successfully prepared by preheating 10 mg mL-1 protein dispersions at various temperatures (80-120 °C) and durations (15-120 min). These findings provide fundamental insights for developing 7S-based protein-fortified systems. © 2023 Society of Chemical Industry.


Assuntos
Temperatura Alta , Estabilidade Proteica , Viscosidade , Propriedades de Superfície , Interações Hidrofóbicas e Hidrofílicas
15.
Food Chem ; 418: 135974, 2023 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-36965384

RESUMO

Skim milk powder (SMP) as well as aqueous dispersions were subjected to dry and wet heat pre-treatment, respectively, to improve the heat stability of recombined filled evaporated milk (RFEM) derived therefrom. However, microrheological analysis revealed that prolonged incubation caused detrimental effects on the heat stability of RFEM, which were thought to be due to protein interactions. SDS-PAGE results indicated that protein aggregation via non-disulfide covalent bonds occurred upon long-time dry or wet heat incubation. This was probably related to some Maillard reaction products, which is sustained by the increase in lactulose and protein carbonyl content. Considerable protein aggregation via disulfide bonds in the serum was found upon wet heat incubation at temperatures of at least 80 °C. Principal component analysis (PCA) revealed that the negative effects of overprocessing on the heat stability of RFEM were predominantly related to protein cross-linking via non-disulfide covalent bonds related to protein carbonylation.


Assuntos
Temperatura Alta , Leite , Animais , Leite/química , Pós/análise , Agregados Proteicos , Carbonilação Proteica , Proteínas do Leite/química
16.
Methods Mol Biol ; 2564: 299-315, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36107350

RESUMO

Green fluorescent proteins (GFPs) have lightened up almost every aspect of biological research including protein sciences. In the field of membrane protein structural biology, GFPs have been used widely to monitor membrane protein localization, expression level, the purification process and yield, and the stability inside the cells and in the test tube. Of particular interest is the fluorescence-detector size-exclusion chromatography-based thermostability assay (FSEC-TS). By simple heating and FSEC, the generally applicable method allows rapid assessment of the thermostability of GFP-fused membrane proteins without purification. Here we describe the experimental details and some typical results for the FSEC-TS method.


Assuntos
Proteínas de Membrana , Cromatografia em Gel , Proteínas de Fluorescência Verde/metabolismo , Proteínas de Membrana/metabolismo
17.
Int J Mol Sci ; 23(24)2022 Dec 16.
Artigo em Inglês | MEDLINE | ID: mdl-36555681

RESUMO

The basis of MreB research is the study of the MreB protein from the Thermotoga maritima species, since it was the first one whose crystal structure was described. Since MreB proteins from different bacterial species show different polymerisation properties in terms of nucleotide and salt dependence, we conducted our research in this direction. For this, we performed measurements based on tryptophan emission, which were supplemented with temperature-dependent and chemical denaturation experiments. The role of nucleotide binding was studied through the fluorescent analogue TNP-ATP. These experiments show that Thermotoga maritima MreB is stabilised in the presence of low salt buffer and ATP. In the course of our work, we developed a new expression and purification procedure that allows us to obtain a large amount of pure, functional protein.


Assuntos
Actinas , Thermotoga maritima , Actinas/metabolismo , Thermotoga maritima/metabolismo , Proteínas de Bactérias/metabolismo , Solubilidade , Nucleotídeos/metabolismo
18.
Adv Sci (Weinh) ; 9(36): e2204017, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36372521

RESUMO

Although the perovskite solar cells have been developed rapidly, the industrialization of perovskite photovoltaics is still facing challenges, especially considering their stability issues. Here, the new type of benzimidazolium salt, N,N'-dialkylbenzimidazolium iodide, is proposed and functionalized to convert the three-dimensional (3D) FACs-perovskite films into one-dimensional (1D) capping layer topped 1D/3D structure either in individual device or module levels. This conformal interface modulation demonstrates that not only can effectively stabilize FACs-based perovskite films by inhibiting the lateral and vertical iodide diffusions in devices or modules, ensuring an excellent operation and environmental stability, but also provides an excellent charge transporting channel through the well-designed 1D crystal structure. Consequently, efficient device performance with power conversion efficiency up to 24.3% is readily achieved. And the large-area perovskite solar modules with high efficiency (19.6% for the active areas of 18 cm2 ) and long-term stability (about 500 h in AM 1.5G illumination or about 1000 h under double-85 conditions) are also successfully verified.

19.
Int J Biol Macromol ; 222(Pt B): 1758-1767, 2022 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-36195233

RESUMO

Phycocyanin (PC), a spirulina-derived protein-chromophore complex, suffers from poor techno-functional properties and is highly susceptible to aggregation and color changes upon heating and pH fluctuations. We tackled these issues by modifying PC via PEGylation. Electrophoresis and Fourier transform infrared spectroscopy proved successful conjugation of methoxy PEG (mPEG) chains on PC after PEGylation. Circular dichroism indicated highly ordered folding states adopted by PEGylated PC, which we attributed to the mPEG chains on the protein surface that sterically stabilized the protein structure. Consequently, the mPEG-PC conjugates exhibited high blue color intensity and improved thermodynamic stability. Further, benefit from an electrostatic shielding effect of mPEG chains, surface charges of PEGylated PC were neutralized over pH 2-9 and the blue hue of PC was stabilized against pH variations. Additionally, the flexible and hydrophilic mPEG polymers on the PC surface promoted protein-protein and protein-water interactions. PEGylated PC thus gained increased protein solubility, techno-functionality (emulsifying, foaming, and gelling performance), and antioxidant activities, when compared to unmodified PC. Heat-induced gels formed by mPEG-PC conjugates exhibited increased stiffness, higher water retention, and weak gel-type rheological properties. After PEGylation, the improved functional properties, bioactivity, and color stability against heat and pH fluctuations will facilitate food and pharmaceutical applications of PC.


Assuntos
Temperatura Alta , Ficocianina , Polietilenoglicóis/química , Proteínas , Coloides , Água , Concentração de Íons de Hidrogênio
20.
Free Radic Biol Med ; 192: 77-83, 2022 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-36113706

RESUMO

Commercial cannabis oil products are widely available in Canada even though there is a significant gap in scientific information regarding them. Oils, such as vegetable oils, are known to undergo oxidative changes through free radical mechanisms when they are heated or aged, but the cannabis oils used in this study did not have expiry dates or best-before usage dates. This led to the question of how these products would be affected with time. We hypothesized that cannabis oils would produce increased concentrations of free radicals in aging-simulated conditions, which would be related to a decrease in cannabidiol (CBD) or Δ9-tetrahydrocannabinol (THC) content. Cannabis oils and their respective vehicles (oils) were heated using two protocols: One (moderate aging method) used a 2-day heating protocol at 50 °C, and the other (enhanced aging method) used a 14-day heating protocol at 70 °C. We used electron paramagnetic resonance (EPR) spectroscopy for free radical analysis using the spin trapping technique using 200 mM PBN and 0.02 mM CuCl2 (for peroxide breakdown to free radicals). For active ingredient analysis (CBD, THC), we used LC/MS. Cannabis oils that contained unsaturated oils as their vehicles, such as olive or sunflower oil, all showed varying degrees of free radical formation. In both aged and unaged oils containing CBD or THC, less free radical formation was detected compared to the vehicle controls. Cannabis oils using medium-chain triglycerides (MCT) showed little or no free radical formation. The most significant decrease in CBD or THC was observed in the products using sunflower oil, to a lesser extent in MCT oil, and THC also decreased in olive oil. These findings are important for consumers and policymakers considering using such products in hot beverages or cooking and highlighting the importance of appropriate storage conditions.


Assuntos
Canabidiol , Cannabis , Cannabis/química , Dronabinol/análise , Radicais Livres , Calefação , Azeite de Oliva/química , Peróxidos , Óleos de Plantas/química , Óleo de Girassol , Triglicerídeos
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