Color changes of ash wood (Fraxinus excelsior L.) caused by thermal modification in air and steam

Color changes of ash wood (Fraxinus excelsior L.) caused by thermal modification in air and steam. Ash wood samples of 20x20x30 mm were subjected to thermal modification in different conditions. The thermal modification was conducted in air at 190 °C and in steam at 160 °C. For both environments modification lasted 2, 6 and 10 hours. Samples color parameters were measured before and after thermal modification on the basis of the mathematical CIELab color space model. Changes in all parameters (L, a and b) were observed, the highest in lightness (L) - darker color. The total color difference (ΔE) and chromaticity change (ΔC) were calculated for all samples. The highest value of ΔE was obtained for wood modified in the air at 190 °C for 10 h. The highest value of ΔC was obtained for wood modified in steam at 160 °C for 10 h. However, the value obtained for wood modified in the air at 190 °C for 10 h were only slightly lower.

Effect of Perforation Dyeing Technique on Color Difference, Colorfastness, and Basic Density of Living Red-Heart Chinese Fir

Red-heart Chinese fir is an excellent geographic provenance of Cunninghamia lanceolata, with high-value red heartwood. However, the formation of red heartwood is usually slow. To quickly cultivate red-heart Chinese fir, we studied perforation dyeing technology on living trees that were 7 years old and efficient in high-value red heartwood formation. Reactive dye (%), penetrant (%), KH2PO4 (%), and pH were selected as influencing factors, and an orthogonal test (L9(3)4) was used. The results showed that the total color difference between the experimental and CK groups ranged from 13.74 to 26.86 NBS, which was a significant visual perception (above 12 NBS). The total color difference before and after soaking in water for 6 h ranged from 2.30 to 5.12 NBS, which belonged to the detectable and identifiable value of the human eye (2~5 NBS). After the injection of the dye liquid, the wood basic density (WBD) was significantly affected after one year. After a comprehensive analysis of wood color difference, colorfastness, and WBD of the orthogonal test, the best dyeing process of juvenile red-heart Chinese fir was reactive dye: 0.8%, penetrant: 0.05%, KH2PO4: 0.3%, and pH: 3.5. The results of this study can provide a reference to improve the value of red-heart Chinese fir, a fast-cultivated, high-value decorative wood material.

Physicochemical properties of extruded ready-to-eat snack from unripe plantain blends, pineapple by-products and stevia

The aim of this research was to evaluate the effect of extrusion temperature (ET 120 – 180 °C), feed moisture content (FMC 16 - 25 g/100 g), pineapple by-products proportion (PBP) (0 - 30 g/100 g) in the unripe plantain flour, and the stevia content (STC 0 - 5 g/100 g) on the physicochemical properties and sensory acceptance of ready-to-eat extruded snacks, through a central compound design, using a single-screw extruder with a compression screw ratio of 3:1. The results were analyzed by response surface. The increase in FMC, PBP and STC decreased (p < 0.05) the expansion index (EI). The increase in ET decreased (p < 0.05) the apparent density (AD), water absorption index (WAI), water solubility index (WSI) and total color difference (ΔE). The increase in FMC decreases EI, WAI, and increase AD and WSI (p < 0.05). The Increase in PBP decreased EI, WSI, and increase AD, hardness (H) and ΔE (p < 0.05). The increase in STC decreased (p < 0.05) EI, and increase AD and H. The treatments with greater general acceptability were those that contained 15 and 30 g/100 g of PBP and STC 2.5 g/100 g, and they were obtained at ET 150ºC and 20.5 g/100 g of FMC, without affecting the physicochemical properties.

The Influence of Drying Temperature on Color Change of Hornbeam and Maple Wood Used as Surface and Inner Layers of Wood Composites

The thermal treatment of wood changes its structure due to the degradation of wood polymers (cellulose, hemicellulose and lignin), so the physical properties of wood are either improved or degraded. Color changes apply not only to natural wood, but also to such wood composites for which some amount of glue is used in their construction (e.g., plywood, blockboard or laminboard). This article is focused on the analysis of hornbeam and field maple wood color changes influenced by drying temperature. Two types of drying modes were used: hot-air mode where the temperature of the drying environment was 60 °C, and high-temperature mode with a drying temperature of 120 °C. The drying mode was divided into two phases depending on the moisture content of the wood. The compared woods had similar values of color coordinates at the beginning of drying. During hot-air drying, the largest changes in color coordinates occurred during the first 24 h. The total color difference between the color at the end and the beginning of drying was 7.3 for hornbeam and 11.1 for maple. The overall color difference between the compared woods was minimal. During high-temperature drying (120 °C), the color changes of the dried woods were more pronounced. In the case of maple wood, there was a very significant change in color and the value of ΔE* was twice as high as for hornbeam. The total color difference between the color at the end and at the beginning of drying was 8.7 for hornbeam and 18.9 for maple.

Effect of Esterification Conditions on the Physicochemical Properties of Phosphorylated Potato Starch

The aim of this study was to evaluate the effect of the temperature (15 or 45 °C) and the duration (15–120 min) of the modification process on the selected physicochemical, thermal, and rheological properties of phosphorylated potato starch. The modified starches contained 93.6–98.2 mg P/100 g (dry weight basis, d.w.b.). Phosphorylation caused color changes with a total color difference between the starches below 0.55, but these changes were less than those that were recognizable by the human eye. The thermal analysis showed two opposite processes appearing during the modification: the loosening of the structure (dominant among starches obtained at 15 °C) and the strengthening of the structure (dominant among starches obtained at 45 °C). The higher phosphorylation temperature reduced native starch recovery from 140% to 87–116% and increased the hysteresis loop area from −169 to 1040. All of the pastes made from the modified starches showed a weaker tendency for retrogradation (during 21 days of storage) than native starches. The results of the regression analysis conducted between the properties of the starch pastes obtained at 45 °C indicated that the modification time appeared to be a better indicator of the rate of modification progress than the phosphorus content. The PCA (principal component analysis) results made it possible to distinguish starch phosphates obtained at 15 °C from those obtained at 45 °C and those from natural starch.

Accelerated Aging Effects on Color Stability of Potentially Color Adjusting Resin-based Composites

SUMMARY The aim of this study was to compare the effects of accelerated aging on the overall color stability of potentially color adjusting commercial resin-based composite resins. Thirty specimens (10 mm diameter and 2.5 mm thick; n=6) were fabricated using five different materials: Estelite Omega, GC Kalore, Venus Pearl, Harmonize, and Omnichroma. Color measurements were taken for each sample using a spectrophotometer before and after submitting samples through the artificial aging process (Q-sun Xenon Test Chamber, 102 min light at 63°C black panel temperature; 18 min light and water spray per ASTM G155) for a total of 300 hours (12.5 days). The total color difference (ΔE*ab) was calculated using SpectraMagic NX software and analyzed using one-way analysis of variance and Tukey test. The results for color change (ΔE*ab) were statistically significant. Omnichroma and Venus Pearl presented superior color stability and the lowest overall color change, whereas GC Kalore and Harmonize presented significant color change that would be considered clinically unacceptable (ΔE*ab &gt; 3.3).

Banana liqueur made with yacon syrup: evaluation of stability during maturation

The aim of this work was to evaluate the stability during maturation of banana liqueurs made with yacon syrup and sucrose. Thus, 20 °GL and 30 °Brix liqueurs were produced using yacon and sucrose syrups at concentrations of 42.8 and 45.0 °Brix. The liqueurs were subjected to two procedures as following: heat treatment at 70 °C for 20 min (tranchage), followed by storage at room temperature for 10 days (T42-T and T45-T); no heat treatment and storage at 50 °C for 10 days (T42-50 and T45-50). The color and turbidity of liqueurs were evaluated daily within 10 days of storage. The alcohol content was evaluated every 2 days. The total color difference (ΔE) was calculated in relation to color at time zero for each treatment. The T42-50 treatment had the lowest turbidity at the end of maturation. The T45-T treatment presented the lowest ΔE value at the end of maturation. The alcohol contents regarding the liqueurs were the same as those contents after elaboration as well as did not change over the maturation time for all treatments.

Effect of Ultrasound Treatment on the Sterilization and Quality of Cucurbita pepo

The influence of ultrasonic technology on the sterilization effect and quality of Cucurbita pepo juice were studied in this paper. The sterilization rate under conditions of control 100W, 200W, 300W ultrasonic, color difference, total chlorophyll content, pH changes on juice Cucurbita pepo were determined. The results showed that the total color difference, browning index, whiteness index and total chlorophyll content of the juice had significant changes, while the pH had no significant changes. Ultrasonic has a certain influence on the sterilization effect of Cucurbita pepo, and ultrasonic treatment is helpful to maintain the quality of pumpkin juice in a certain range. In the future, it is hoped that ultrasonic technology will combine with other technologies to achieve commercial sterility while minimizing the loss of quality in Cucurbita pepo.

Novel Color Change Film as a Time–Temperature Indicator Using Polydiacetylene/Silver Nanoparticles Embedded in Carboxymethyl Cellulose

Time–temperature indicators (TTIs) can be important tools in product applications to monitor food quality losses, especially for fruits and vegetables. In this context, the effects of silver nanoparticles (AgNPs) and glycerol on the color change of polydiacetylene/AgNPs (PDA/AgNPs) embedded in carboxymethyl cellulose (CMC) film as time–temperature indicators (TTIs) were investigated. A CMC film prepared with 30 mg/L AgNPs and a 1:3 (v/v) PDA:AgNP ratio exhibited a faster color change than under other conditions. At 35 °C, the films with PDA/AgNPs changed color from purplish-blue to purple and purple to reddish-purple over time due to the higher thermal conductivity of AgNPs and larger PDA surface area exposed to specific temperatures. The total color difference (TCD) of PDA/AgNP-embedded CMC film directly changed with regard to time and temperature. However, adding glycerol to the system resulted in a symmetrical chemical structure, a factor that delayed the color change. Scanning electron micrographs showed AgNPs embedded in the CMC films. Transmission electron micrographs indicated a core-shell structure of PDA/AgNP vesicles in the CMC matrix. PDA/AgNP vesicles were confirmed by second derivative Fourier transform infrared spectroscopy, with a new peak at 1390–1150 cm−1. The kinetics of TTIs from PDA/AgNP-embedded CMC films yielded an activation energy of 58.70 kJ/mol.

Effects of UV-C Irradiation and Thermal Processing on the Microbial and Physicochemical Properties of Agave tequilana Weber var. azul Extracts at Various pH Values

The effects of UV-C irradiation (at doses of 8.16, 10.93, 16.17, and 33.29 mJ/cm2) on the physicochemical and microbiological properties of Agave tequilana Weber extracts at various pH values (4.5, 5.5, and 6.5) were evaluated. Thermal treatment (TT) was used as a control (85 °C for 30 s). Both processed (UV-C or TT) and unprocessed (UP) extracts were investigated. The UV-C dose and the pH significantly (p < 0.05) affected the inactivation of total coliforms (TC), total aerobic mesophiles (TAM), and yeasts and molds (YM). UV-C doses of 10.93 mJ/cm2 at pH 4.5 and 33.29 mJ/cm2 at any agave extract pH completely inactivated the native microbial load compared to TT. The total polyphenols (TP), antioxidant activity (AA), and sugar content did not change in the agave extracts at any dose, but the total flavonoid (TF) content decreased at doses > 16.17 mJ/cm2 at the evaluated pH values. Although the color of the agave extracts (L*, a*, and b*) was significantly affected, the total color difference (∆E) did not change after processing compared to the ∆E in the UP extracts. TT further reduced all the physicochemical properties of the agave extracts compared to UV-C processing. The results suggest that UV-C continuous flow technology can be used to stabilize agave extracts at doses of 10.93 mJ/cm2 and pH 4.5, while preserving their functional properties.