Influence of dipping time on uptake of preservative solution, adsorption, penetration and fixation of copper-ethanolamine based wood preservatives

Copper-ethanolamine based wood preservatives are the most important products for protection of wood in use class III and IV applications. These preservatives can be applied using different procedures. One of them is dipping, a method which is predominantly used in less industrialised countries. The most important parameter, that influences the quality of this treatment, is dipping time. Influence of various dipping times on copper retention, adsorption, penetration, colour of the specimens and copper fixation was examined. In this paper copper-ethanolamine solutions of two different concentrations were utilised (c_Cu=0.05% or 0.25%). The results showed that longer dipping treatments resulted in higher uptakes of preservative solution, better penetrations and lower leaching of copper-ethanolamine based wood preservatives from Norway spruce wood. After one week of dipping, samples retained on average 275 kg/m³ of preservative solution, copper active ingredients penetrated on average 3 mm into the specimens, and only 2.3% of copper was emitted from wood impregnated with aqueous solution of the higher concentration, when subjected to ENV 1250 leaching procedure.     

Effect of hot air post-treatments on copper leaching resistance in ACQ-D treated Chinese fir

Chinese fir (Cunninghamia lanceolata Hook.) wood cubes (19?×?19?×?19 mm³) were treated with amine copper quat-type D (ACQ-D) solution and fixed with different hot air post-treatments. The effects of temperature, relative humidity, duration, air circulation of post-treatment as well as the copper retention in the treated wood on copper leaching were investigated. With the help of ultraviolet or visible spectroscopy (UV/VIS), the valence conversion of copper in treated wood post-treated with optimal post-treatment conditions was investigated, and its relation with copper leaching was also discussed. The results showed that besides temperature and relative humidity, air circulation during hot air post-treatments also had a significant effect on accelerating copper fixation in ACQ-D treated wood. 70 °C, 80% R.H. with good air circulation provided a suitable condition for complete fixation of copper in a short period. After the applied post-treatments, up to 11.3% cupric copper reduced to cuprous form. A higher copper conversion rate usually corresponds to lower copper leaching, which is consistent with the contribution of lower water solubility cuprous copper.     

Process related copper leaching during a combined wood preservation process

A combined wood impregnation process including impregnation with a chromium-free wood preservative and oil treatment was evaluated with regard to leaching of copper during the oil process. Two different experimental setups make up the balance of copper content in oil, wood samples and condensate water, also taking different fixation times and process durations into account. Copper is sufficiently fixed after 24 hours, and leaching of copper into the oil is low. Increasing the oil process time does not lead to increased leaching. The hot oil treatment of impregnated wood under vacuum atmosphere is a fast drying method without major negative consequences for the impregnated copper.     

Copper stabilization in ACQ-D treated wood: retention, temperature and species effects

The rates of stabilization or fixation of copper in ACQ-treated wood were compared for different post treatment conditioning temperatures (22°C and 50°C), solution concentrations (0.4–2.3%) and wood species. In some species, sapwood/heartwood differences were evaluated. The rate and extent of copper stabilization were estimated from changes in concentration of expressed solution at different times after treatment. The quality of the stabilization reaction was evaluated based on leaching performance of the wood after conditioning. Copper stabilized much faster at lower ACQ retentions and when conditioned at 50°C compared to high retentions and stabilization at 22°C. High retention treatments held without drying at 22°C could require five weeks or more for the copper to stabilize in the wood. Generally species effects were minor for the species evaluated, except for Douglas-fir in which copper reacted more quickly than in other species.     

Preservative treatment of Douglas-fir lumber by the passive impregnation method with copper azole

Laser incised dry (mc=18%) and green (mc=33%) Douglas-fir was treated by the passive impregnation method of wood preservation having two different incising densities (7500 and 10000 holes/m²) and dipping times (3 and 12 hours). A 0.68% active ingredient solution of Copper Azole Type B (Tanalith CY) preservative was used in this study. The preservative retention and penetrated area were measured. The total preservative retention varied from 1.61 to 2.68 kg/m³ depending on the moisture content of wood and conditions of preservation, and in all cases it surpassed the minimum retention requirement for above ground use. The maximum penetrated area for dry lumber (mc=18%) was 96 and 88% across and along the grain, respectively. For green lumber (mc=33%), it was 90 and 85% across and along the grain, respectively.     

Boron fixation in wood: studies of fixation mechanisms using model compounds and maritime pine

The purpose of the research work reported in this paper was to study the kinetics and thermodynamics of reactions of some boron compounds with some simple wood model compounds and with maritime pine (Pinus pinaster Ait.). The wood model compounds were selected in order to reproduce in a simple way the possible reactions boron may undergo with wood. Two boron compounds were tested with the wood: sodium tetraborate decahydrate (borax) and boric acid. Boron containing solutions applied to wood and model compounds were tested in such a way that they could lead to the insolubilization of boron or to its chemical fixation. Thermodynamics of boric acid fixation on the wood surface was studied. Results suggest that, even though boron reacts faster with polysaccharides than with lignin, all reactions are very slow at 20 °C. Adsorption should be the preferential mechanism for the bonding of boric acid to wood. This weak bond explains why boron tends to leach out from wood in wet conditions after conventional preservative treatments.     

Air emission from timber drying: high temperature drying and re-drying of CCA treated timber

The nature and mass flows of atmospheric emissions from an industrial kiln, drying radiata pine (Pinus radiata D.Don) timber at 140°C dry bulb and 90°C wet bulb, which was subsequently copper-chrome-arsenic (CCA) treated and redried at 90°C dry bulb and 60°C wet bulb, were assessed by measuring the concentration of chemical components in the kiln atmosphere at regular time intervals and determining air-flows and temperature differentials across the stack. The volatile organic compounds (VOCs) emitted were trapped and analyzed by GC-MS. The two major VOCs found during high temperature pre-drying and CCA re-drying were α-pinene and β-pinene, which made up 87% and 60% of the total discharge (2433 and 145 g/m³ wood), respectively. Most of the VOC fraction was released during the early stages of drying. The polar compounds were trapped in water. Total combined amount of methanol, ethanol, acetic acid and formic acid released over the two runs were 283, 281, 117, and 260 g/m³ wood, respectively. The aldehydes were trapped in 2,4-dinitrophenyl-hydrazine solution and the aldehyde derivatives analysed by HPLC. The total release of formaldehyde and acetaldehyde during the high temperature pre-drying run were 13 and 15 g/m³ wood and the CCA re-drying run were 14 and 4 g/m³ wood, respectively.     

Properties of Orange Juice with Supercritical Carbon Dioxide Treatment

The effects of supercritical CO₂ (SC-CO₂) on the microbiological, sensory (taste, odour, and colour), nutritional (vitamin C content), and physical (cloud, total acidity, pH, and °Brix) qualities of orange juice were studied. The CO₂ treatment was performed in a 1 litre capacity double-walled reactor equipped with a magnetic stirring system. Freshly extracted orange juice was treated with supercritical CO₂, pasteurised at 90°C, or left untreated. There were no significant differences in the sensory attributes and physical qualities between the CO₂ treated juice and freshly extracted juice. The CO₂ treated juice retained 88% of its vitamin C, while the pasteurised juice was notably different from the fresh juice and preserved only 57% of its vitamin C content. After 8 weeks of storage at 4°C, there was no microbial growth in the CO₂ treated juice.     

A simple fabrication of superhydrophobic wood surface by natural rosin based compound via impregnation at room temperature

A two-step impregnation method containing first modification with natural rosin based compound (maleic rosin) and subsequent coating with TiO₂ particles was used for the fabrication of a stable superhydrophobic wood surface. The superhydrophobic property of the treated wood was measured by static contact angel (CA) and dynamic CA. The morphology and chemical composition of the superhydrophobic wood surface were analyzed by scanning electron microscopy and energy dispersive X-ray spectroscopy. The chemical bonds between maleic rosin/TiO₂ and wood were illustrated by Fourier transform infrared spectroscopy. The water CA of the modified wood surface could reach up to 157°. The prepared superhydrophobic wood surface still maintained the superhydrophobic property when being immersed in water for 1 week or irradiated under scorching sunlight for 1 week or boiled at 100 °C for 10 h. Possible formation mechanism of superhydrophobic composite surface on the wood substrate was discussed in detail.     

Effect of carbon dioxide on the inactivation of florida spiny lobster polyphenol oxidase

Florida spiny lobster (Panulirus argus) polyphenol oxidase (PPO) exposed to CO₂ (1 atm) at 33, 38, and 43°C showed a decrease in enzyme activity with increased heating time. Enzyme inactivation by CO₂ was faster for PPO heated at 43 than at 33 or 38°C. Inactivation kinetics revealed PPO was more labile to CO₂ and heat in the range 33–43°C than to heat alone. Kinetic data also revealed that CO₂, in addition to pH changes, was involved in the loss of PPO activity. Studies using get electrophoresis showed no differences in protein patterns and isoelectric point between CO₂-treated and non-treated control. The pH of CO₂-treated PPO stock solution was brought back from 5.4 to 8.0 after 6 weeks of frozen-storage and no enzyme reactivation was observed.     

Effect of Citric Acid Modification of Aspen Wood on Sorption of Copper Ion

Abstract

Milled aspen wood was thermochemically modified with citric acid for the purpose of improving the copper (Cu²⁺) ion sorption capacity of the wood when tested in 24-hour equilibrium batch tests. The wood-citric acid adducts provided additional carboxyl groups to those in the native wood and substantially increased Cu²⁺ ion uptake of the modified wood compared with that of the unmodified wood. Sorption capacity (q_e) measured with an unbuffered standard solution increased to a maximum of 7.9 mg Cu²⁺ ion/g of wood (treated) from 1.3 mg Cu²⁺ ion/g wood (untreated). When measured with a buffered standard solution, the q_e increased to a maximum of 13.8 mg Cu²⁺ ion/g of wood (treated) from 4.1 mg Cu²⁺ ion/g wood (untreated). The treatment necessary for maximum q_e was 2 hours at 130°C. Modification treatments included three time periods (2, 4, 6 hours) and three temperature regimes (110, 120, 130°C). To further evaluate the efficacy of modification treatments, weight change after treatment was monitored as an indirect measure of bound citric acid. It was found that increases to the original mass of greater than about 30% were associated with no further increase or a decline in q_e. The contribution of citric acid ester linkages to increasing mass at longer reaction times was monitored with ATR/FTIR.     

Influence of Spray-Drying Conditions on Physical and Morphological Characteristics of Microencapsulated Benzoic Acid

Benzoic acid is widely used as a preservative in the food and feed industry, and microencapsulation is important in the application of this ingredient in various food products. The objective of this work was to evaluate the effect of benzoic acid concentration and drying air temperature on the physical characteristics of powders produced by spray drying, using maltodextrin and modified starch as the wall materials. A rotatable central composite design was used; the independent variables were inlet air temperature (145–180 °C) and benzoic acid concentration (2–10 %, m/m). Maximum yield was obtained when higher concentrations of benzoic acid and higher inlet air temperatures were applied. The highest microencapsulation efficiency was reached at intermediate temperatures (160 °C) and low concentration of benzoic acid. The particles size (D _[4,3]) ranged from 24.99 to 29.52 μm and, in general, presented amorphous structure, spherical shape with rough surfaces and had no cracks The optimum condition, considering all the response variables together, was drying air temperature 169 °C and benzoic acid concentration 6 % (m/m). Under these conditions, the particles presented solubility of 75.96 g/100 g and wettability of 56.8 s/g. Moreover, the process showed microencapsulation efficiency of 76.77 g/100 g and yield of 40.1 %. Spray drying was considered a potential process to provide microencapsulated benzoic acid.     

Gelatine–starch films: Physicochemical properties and their application in extending the post‐harvest shelf life of avocado (Persea americana)

BACKGROUND: Several storage techniques have been developed to extend the post‐harvest shelf life of horticultural products. One method involves the use of edible or biodegradable coatings. Such coatings are made of biological materials that are used to coat fresh products, providing a semi‐permeable barrier to water vapour and gases, e.g. O₂ and CO₂. The influence of starch concentration, glycerol content and pH on the carbon dioxide permeability (CO₂P) and mechanical properties of gelatine–starch edible films were evaluated. RESULTS: Results showed that increments in the starch concentration and pH resulted in higher CO₂P values. Film puncture strength increased when the starch concentration decreased and the maximum resistance value (32.6 N) was obtained at pH 6. Deformation was mainly affected by glycerol and starch content. Some films were chosen in order to evaluate their effect, as coatings, in the post‐harvest shelf life of avocados (Persea americana Mill c.v. Hass). Fruits were immersed in the coating solutions, air dried and stored at two temperatures. Changes in colour, weight loss and pulp firmness were determined in fruits stored at 6 °C. In addition, respiration rate was measured in avocados kept at 20 °C. CONCLUSION: The application of gelatine–starch coatings delayed the ripening process of avocados, as indicated by a better pulp firmness and retention of skin colour, and lower weight loss of coated fruits in comparison with control avocados. The coatings also resulted in a delayed respiratory climacteric pattern, by 3 days, for coated fruits. Copyright © 2007 Society of Chemical Industry     

Preservation of raw milk with CO2

The effect of CO₂ on the growth of psychrotrophic milk spoilage organisms was studied, both in raw fresh milk and in pure cultures of three species ofPseudomonas growing in sterilised milk. Changes of sensory properties of CO₂-treated samples after heat treatment were also analysed. Inhibition of psychrotrophic growth at 7 °C in milk treated with CO₂ to a pH 6.2 or 6.0 was impaired by a gradual reduction of the CO₂ content during storage. Growth inhibition was considerably improved by pH adjustment at 24-h intervals. Sensory analysis showed significant differences between non-acidified and acidified samples after heat treatment at 75 °C for 20 s or 110 °C for 5 min. No sensory differences were found between non-acidified and acidified milks degassed before heat treatment.     

Storage of Morwong (Nemadactylus macropterus Bloch and Schneider) in Combinations of Polyphosphate, Potassium Sorbate and Carbon Dioxide at 4o C

Combinations of potassium sorbate and polyphosphate, in conjunction with vacuum or modified atmosphere packaging, were assessed for their preservative effects on morwong fillets (pH 6.75) stored at 4°C. Vacuum packaged and/or frozen fillets were used as comparisons for microbiological and taste panel analysis. A combination of potassium sorbate, polyphosphate and 100% CO₂ was the most effective packaging regime. Potassium sorbate on vacuum packaged fish was more effective than a 100% CO₂ atmosphere alone. Polyphosphate had no apparent additional effect on fillets stored under vacuum with or without potassium sorbate.     

Physicochemical,Phytochemical and Mycological Characteristics of Italia Muscat Raisins Obtained Using Different Pre-treatments and Drying Techniques

Raisins represent an economically important grapevine by-product. However, their quality is largely dependent on drying techniques and processing conditions. In this context, two drying processes were monitored: hot air drying in a convective oven and greenhouse drying. Grape berries were previously subjected to two chemical pre-treatments (olive oil and K₂CO₃ emulsion dipping (I) and NaOH solution bleaching (II)). Pre-treated grapes processed using both methods were compared with sun-dried samples. The results show that oven drying was more efficient and rapid (5 days) as compared with greenhouse drying (13 days). The end moisture content of grapes varied from 16.12% to 22.25% on a wet basis in dried samples, respectively. Significant differences in the pH value (3.85–4), acidity (1172.5–2730 mg TA/100 g DW) and total sugars (31.5–49.7%) were also observed, between raisin samples subjected to both treatments and drying methods, whereas protein levels (1–1.25%) were not affected. The analysis of minerals indicates that greenhouse-dried raisins had high amounts of calcium (Ca), magnesium (Mg) and sodium (Na). The highest polyphenol (417.70 mg GAE/100 g DW), flavonoid (115.87 mg CE/100 g DW) and tannin (368.13 mg CE/100 g DW) contents were recorded in sun-dried samples, respectively. The distribution of fungal flora shows a noteworthy variability among raisin samples, with a marked abundance of ochratoxinogenic species such as Aspergillus ochraceus and Aspergillus carbonarius (15.56% and 10.41%, respectively). Italia Muscat raisins processed using oven drying could be an economically interesting alternative to manage the excessive grapes production and consequently solve related marketing issues.     

Study of the quality changes and myofibrillar proteins of white shrimp (Litopenaeus vannamei) under modified atmosphere packaging with varying CO2 levels

This paper studied the effect of modified atmosphere packaging (MAP) with 40–80 % CO₂, 5 % O₂ and 15–55 % N₂ on the quality of Pacific white shrimp (Litopenaeus vannamei) during 10-day storage at (4 ± 1) °C. The effect of CO₂ on the shrimp quality was compared by analyzing the quality indices such as total viable counts (TVC), total volatile basic nitrogen (TVB-N), pH and polyphenoloxidase (PPO) activity, whiteness and sensory attributes. Changes in myofibril length of shrimp flesh were also studied, which correspond to flesh softening. The findings suggest that the shrimp packaged in modified atmosphere had better quality indices than the control. Compared the MAP-batches, 80 % CO₂/15 % N₂/5 % O₂ led to the lowest level of TVC, TVB-N values, PPO activity and the highest sensory scores. Therefore, high-CO₂ packaging should be recommended to delay quality loss of shrimp during transportation and storage.     

Fire resistance of wood treated with a cationic silica sol

Wood was treated with the cationic silica sol (CSS) Levasil 200S and dried at various temperatures (room temperature, 40, 60, 80 and 103 °C). A water leaching test revealed fixation of the silica in wood even after drying at room temperature. Maximum cross sectional swelling of the specimens decreased from 15.6 % (untreated control) to 13.0 %, when treated wood was dried at 103 °C; cell wall bulking values were also negative (?2.3 %), indicating a thermal degradation of the cell wall polymers catalyzed by the CSS. Penetration of the CSS into the cell wall did not occur. A simple flammability test revealed increased fire resistance of the treated wood. Mass loss and velocity of mass loss as well as burning time were reduced; glowing of the formed charcoal was completely prevented. The effectiveness increased with increasing weight percent gain of the CSS in the wood. Thermo gravimetric analysis under nitrogen atmosphere displayed only minor reduction in the initial temperature of thermal decomposition for wood treated with CSS as compared to the control. In the presence of oxygen the resulting charcoal showed comparable thermal behaviour to the control. The yield of charcoal after pyrolysis was increased to a minor extent (from 19.9 to 23.0 %), indicating that the release of combustible gases was hardly reduced. The mode of action of enhanced fire resistance due to CSS-treatment is discussed.     

Solubility of carbon dioxide in a seafood model product with fish oil

The solubility of carbon dioxide (CO₂) in a seafood model product with various amounts of salmon oil was investigated. Differential scanning calorimetry analysis of the salmon oil gave an onset temperature for crystallization at ?14.75 ± 0.74 °C, showing that the oil was in liquid state in the temperature range used in this experiment (1–8 °C). Solubility of CO₂ in salmon oil in liquid state was similar to water, with the same temperature dependency as water. Increased storage temperature decreased the amount of dissolved CO₂ and increased the headspace CO₂ and headspace gas volume. Headspace gas composition at equilibrium was linearly (R ² = 0.979) related to the composition of the packaging gas, while increasing CO₂ in the packaging gas increased the headspace gas volume and the amount of dissolved CO₂ in the product. When designing modified gas-packaging regimes for products with marine fat, sum of fat and water can be used to estimate the amount of dissolved CO₂ in the product.