Photoelectric conversion efficiency of organic-inorganic perovskite solar cells has been rapidly raised and attracted great attention in recent years. The quality of perovskite films is vital for the ...performance of devices. We used the anti-solvent method to prepare CH3NH3PbI3 thin films by spin coating and dried them at various temperature to transform adduct MAI·PbI2·DMSO into CH3NH3PbI3. We researched in detail on the relationship between surface morphology of MAPbI3 thin films fabricated by the anti-solvent method and various drying temperature. We found that surface roughness and grain size of CH3NH3PbI3 films together increased with increasing drying temperature. The larger grain size could efficiently reduce crystal boundaries which is advantageous for the suppression of photo-induced charge carrier recombination resulting in increase of FF. However, increase of surface roughness resulted in larger contact area at interface which might produce more tarp states and poorer wettability of HTM solution leading in decrease of Jsc. Surface morphology of MAPbI3 layer on the performance of solar cell devices is also an important research issue. By optimizing the drying temperature to 60 °C, the highest efficiency of 14.4% was achieved for the CH3NH3PbI3-based solar cell devices.
•CH3NH3PbI3 surface roughness influences the wettability of HTM solution.•Interface area and defects should be increased and decreased, respectively.•Drying temperature of CH3NH3PbI3 solution film was optimized to 60 °C.
•GA cross-linking improved the application properties of collagen casing films.•Superior mechanical properties could be obtained by regulating drying temperature.•GA cross-linking improved the low ...temperature thermostability of films.•GA cross-linking impeded the depolymerization of collagen triple helix.•Higher drying temperatures disrupted the orientation of collagen fibers.
The physicochemical properties of collagen casings were successfully improved by glutaraldehyde (GA) cross-linking, where the properties could be further regulated by drying temperature. Transverse direction (TD) showed a lower heat shrinkage rate than that in machine direction (MD). GA cross-linking significantly improved the mechanical properties of films under wet and boiled state. The mechanical properties of films in MD were more susceptible to wet and boiling water. The chemical composition was unchanged after GA cross-linking, but higher drying temperatures led to higher triple helix contents. The GA cross-linking mainly promoted the low temperature thermostability of collagen casings. All film samples had a rough fibrous morphology and a majority of collagen fibers was oriented under the lower drying temperature (55 ℃). These results reported in this study can be used to better guide the preparation of collagen casings.
The effects of drying temperature (50, 60, and 70°C) and absolute humidity (65, 90, 115, 140 g/kg at the initial stage) on drying kinetics and color attributes of apricot halves under process-based ...drying temperature and humidity integration control (PDTHIC) were investigated. Results indicated that appropriate PDTHIC could reduce the drying time by 18.75% compared to the control group. The absolute humidity parameter should be controlled well rather than continuously dehumidify for traditional practices. The moisture effective diffusivity (D ₑff) at 70°C presented drastic fluctuations with increasing absolute humidity parameters, calculated using the Weibull distribution model. The activation energy (E ₐ) of samples treated by continuous dehumidification and PDTHIC were 31.40 and 74.18 kJ/mol, respectively. The variation trend of color parameters was different from the conventional hot air drying probably due to the dehydration mechanism. Observation of the microstructure of the dried samples indicated that the PDTHIC process can enhance the drying rate of apricot through generating a larger pore network compared to continuous dehumidification at the same temperature. The findings of the current work clearly indicated that process-based drying temperature and humidity integration control enhances the drying kinetics of apricot halves, leading to a promising technology for energy savings.
•Coal after drying is more prone to oxidation and spontaneous combustion.•Developed pore structure of dry coal promotes O2 transport and strengthens oxidation.•The hydroxyl content in coal decreases ...but the CO content increases after drying.•Carbonyl compounds undergo thermal decomposition and generate free radicals.•Free radical oxidation releases carbon oxides and forms oxygen-containing groups.
Heat treatment of coal under nitrogen is an effective technology to reduce water content and upgrade lignite, but the subsequent oxidation behavior and spontaneous combustion characteristic of dried coal are unclear, possibly posing a threat to lignite transportation and storage. In this study, raw coal and dried coal at different temperatures were selected and oxidation parameters were first analyzed by temperature-programmed experiment. The carbon oxides emissions and oxygen consumption of dried coals are obviously higher than that of raw coal, and increase with rising dehydration temperature, indicating coal after drying is more prone to oxidation and spontaneous combustion. Then, the physical structure, chemical groups and free radicals of coal were determined by nitrogen adsorption, FTIR and ESR technology. During drying process, gas release and water evaporation increase pore diameter and pore volume of coal, thus improving O2 transport capacity and oxidation rate. The hydroxyl content in coal decreases, but the CO content increases due to the polycondensation and dehydration reaction of hydroxyl groups after high-temperature drying. Meanwhile, carbonyl compounds and carboxyl groups undergo thermal decomposition and generate free radical active sites on the coal surface. The subsequent oxidation of accumulated free radicals not just release large amounts of carbon oxides, but also contribute to the formation of oxygen-containing groups inside coal with the rise of temperature, accelerating coal-oxygen reaction. Therefore, it is proposed that heat treatment expands physical channels, increases the content of CO groups, and enhances the content of active sites, which leads to vigorous oxidation of dried coal and even uncontrolled coal fires.
Since high temperature facilitates the gelatinization of starch, temperature is generally recognized to play a key factor in the digestibility of starch during the drying process. However, the food ...matrix is complex and other factors may influence the digestibility of starch in dried whole flour. In this study, the drying temperature varied depending on the drying method used, i.e., freeze drying (−45 °C), natural drying (25 °C), vacuum drying (40 °C), hot-air drying (50 °C) and roasting (200 °C), and a pretreatment with ascorbic acid or salicylic acid was used to produce whole chestnut flour. The estimated glycemic index was higher for hot-air dried and freeze-dried chestnut flour, while that for vacuum-dried, roasted and phenolics-pretreated hot-air dried chestnut flour was lower than that for naturally-dried chestnut flour. During the drying process, the digestibility of starch was correlated with the drying temperature, long- and short-range molecular order, and other compounds in the chestnut.
•Digestibility of starch from whole chestnut flour varies with drying temperature.•Freeze or hot-air drying induces high digestibility of starch in whole chestnut flour.•Vacuum drying contributes to the low digestibility of starch in whole chestnut flour.•Roasting leads to low starch digestibility despite the geletinization of starch.•Phenolic pretreatment increases the cystallinity of starch and reduces the digestibility.
Camu-camu processing coproducts can present a high concentration of bioactive compounds with antioxidant characteristics. However, the application of these coproducts in food products is little ...explored. Thus, this study aimed to evaluate the effect of different drying temperatures on camu-camu coproducts in relation to the bioactive compound concentration and the effect of substitution of wheat flour by this coproduct on the characteristics of cookies. Camu-camu coproducts were dried at 50 °C, 60 °C and 70 °C and evaluated for proximate composition, phenolic profile and the total phenolic and antioxidant potential (DPPH, FRAP, ORAC assays). Cookies were produced with 5%–20% replacement of wheat flour by the coproduct powder and characterized in relation to hardness, spreading factor, specific volume and the total phenolic and antioxidant potential. The camu-camu coproduct powder dried at 70 °C showed the highest concentration of total phenolic and antioxidant potential. A total of 11 flavonoids were identified for camu-camu coproduct regardless of drying temperature. The incorporation of camu-camu coproduct powder, with a maximum substitution of 20%, did not affect the physical properties of the cookies when compared to the control cookies, improving total phenolics and antioxidant potential, confirming a possible to insert this coproduct in food industry.
•Drying temperatures influenced the total phenolics content of camu-camu coproducts.•Eleven different phenolic compounds were evidenced in camu-camu coproducts.•The maximum percentage of replacement of wheat flour by camu-camu coproduct was 20%.•Cookies produced with camu-camu byproduct showed an antioxidant potential.
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•Pseudo-bilayer edible film with higher hydrophobicity was prepared.•Phase separation is necessary for preparation of pseudo-bilayer film.•Adjusting drying temperature and ...homogenization intensity achieves phase separation.
The present study aims to develop an agar/maltodextrin-beeswax (A/M-BW) pseudo-bilayer film with high surface hydrophobicity by adjusting drying temperatures and homogenization conditions. Attenuated total reflectance-Fourier transform infrared determined the chemical components of the upper and lower surfaces of the films. X-ray diffraction characterized the crystalline behavior of film matrix. Scanning electron microscopy explored the distribution patterns of BW and phase separation phenomenon. Atomic force microscopy revealed the surface roughness of film. The pseudo-bilayer film prepared at 8000 rpm for 1 min (A/M-BW-8000-1) had the highest tensile strength (20.57 MPa), Young’s modulus (640.60 MPa), contact angle (92.9°), and the lowest water vapor permeability (2.18 × 10−12 g m−1 s−1 Pa−1). The A/M-BW pseudo-bilayer film with excellent surface hydrophobicity and mechanical properties was obtained at higher drying temperature and lower homogenization intensity. The A/M-BW pseudo-bilayer film has promising potential for application in food packaging which requires higher water vapor resistance.
Bromelain is a proteolytic enzyme that can be found in all parts of pineapple plant varieties. Pineapple crown (PC) has higher bromelain activity than other pineapple wastes such as peels and leaves. ...This study isolated bromelain from one variety of PC, namely Honi, and determined the optimum drying temperature as well as concentration of ammonium sulphate to obtain the best bromelain characteristics such as protein content, unit activity and specific activity. Honi PC was dried at various drying temperatures (35, 40, 45, 50, and 55 °C), and then extracted and purified using ammonium sulphate in various concentrations (20, 40, 60, and 80%), in order, to get bromelain. Furthermore, the yield of isolated bromelain was calculated and the protein content, unit activity and specific activity of bromelain characterised. The highest yield of crude bromelain (CB) was achieved at 35 °C. However, the highest protein level, unit activity and specific activity of CB were achieved at 55 °C (p < 0.05). Purification of CB using concentrations of ammonium sulphate in the range 40 to 80% resulted in a higher protein level (p < 0.05). The highest unit activity and specific activity of bromelain were achieved at a 60% concentration of ammonium sulphate (p < 0.05). 55 °C and 60% were the optimum drying temperature and concentration of ammonium sulphate respectively to achieve the best characteristics (2.16% protein level, 1.61 U/mL unit activity and 0.75 U/mg specific activity) for bromelain isolated from Honi PC. Honi PC isolated bromelain was shown to inhibit the browning reaction on apple fruits. The agroindustry waste product, Honi PC, has potential as a future alternative bromelain source.
Drying is an important factor in the formation of green tea flavor. In this study, metabolomic analysis were used to detect characteristic components of four green teas with clean aroma (CA), ...chestnut-like aroma (CLA), bean-like aroma (BLA) and high-fired aroma (HFA) produced by adjusting drying temperature. The sensory evaluation results showed that the tea dried at 90°C, 110°C, 140°C and 160°C had a clean aroma, chestnut-like aroma, bean-like aroma and high-fired aroma respectively. A total of 95 volatile compounds were identified. Linalool, naphthalene, 2-methyl-naphthalene, 1-octen-3-ol contributed most to the clean aroma. 1,2-dihydro-1,1,6-trimethyl-naphthalene was the key component of the chestnut-like aroma. 2,3-diethyl-5-methyl-pyrazine, 2-methyl-butanal, 3-ethyl-2,5-dimethyl-pyrazine had the biggest contribution to the bean-like aroma. 2,3-diethyl-5-methyl-pyrazine, 3-ethyl-2,5-dimethyl-pyrazine and 2-ethyl-5-methyl-pyrazine contributed most to the high-fired aroma. A total of 838 non-volatile compounds were detected and amino acids, saccharides decreased while catechins, flavonols increased during the increasing of drying temperature. It's found that they were related to the taste of umami, astringency and bitterness. This result provides a guidance and theoretical basis for the processing of green tea with different aroma types.
•Four aroma types of green teas were manufactured by different drying temperatures.•Naphthalene and its derivatives contributed most to clean and chestnut-like aroma.•Pyrazine derivatives contributed most to bean-like and high-fired aroma green teas.•The higher the drying temperature, the more bitter and more astringent of green tea.
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