Heat and mass transfer during fry-drying of sewage sludge

Deep-frying, which consists of immersing a wet material in a large volume of hot oil, presents a process easily adaptable to dry rather than cook materials. A suitable material for drying is sewage sludge, which may be dried using recycled cooking oils (RCO) as frying oil. One advantage is that this prepares both materials for convenient disposal by incineration. This study examines fry-drying of municipal sewage sludge using recycled cooking oil. The transport processes occurring during fry-drying were monitored through sample weight, temperature, and image analysis. Due to the thicker and wetter samples than the common fried foods, high residual moisture is observed in the sludge when the boiling front has reached the geometric center of the sample, suggesting that the operation is heat transfer controlled only during the first half of the process followed by the addition of other mechanisms that allow complete drying of the sample. A series of mechanisms comprising four stages (i.e., initial heating accompanied by a surface boiling onset, film vapor regime, transitional nucleate boiling, and bound water removal) is proposed. In order to study the effect of the operating conditions on the fry-drying kinetics, different oil temperatures (from 120 to 180 degrees C), diameter (D = 15 to 25 mm), and initial moisture content of the sample (4.8 and 5.6 kg water(.)kg(-1) total dry solids) were investigated.

Effects of high temperature on the growth and composition of sugarcane internodes

Sugarcane grown in the Ord River district of Western Australia has lower sucrose content than expected from earlier trials and experience in other irrigated districts. High temperatures have been hypothesised as a possible cause. The effects of high temperature (above 32 degrees C) on growth and carbon partitioning were investigated. A temperature regime of (25-38 degrees C) was compared with (23-33 degrees C). In one experiment, 7-month-old plants of cvv. Q117 and Q158 were subjected to the treatments for 2 months. In another experiment, the plants were allowed to regrow (ratoon) for 6 months. In both experiments, the higher temperature resulted in more, shorter internodes and higher moisture content. Most internodes from plants in the higher temperature treatment had lower sucrose content than internodes from the lower temperature. On a dry mass basis the internodes from the plants in the higher temperature had proportionately more fibre and hexoses but lower sucrose. Combined with an increased number of nodes in a stem of similar or shorter length this would result in higher stalk fibre and lower sucrose content. The data provided evidence that sugarcane partitions less carbon to stored sucrose when grown under high compared with low temperatures. The two cultivars partitioned carbon between soluble (sugars) and insoluble (fibre) fractions to different degrees. These experiments also indicate that the current models describing leaf appearance and perhaps sugarcane growth at temperatures above 32 degrees C, in general, need revision.

Optimum harvest maturity for guayule seed

Guayule (Parthenium argentatum Gray) is a rubber-producing shrub native to the semi-arid region of north central Mexico and southwestern Texas. Timely harvest is critical to achieve maximum seed viability, vigour, and yield. The objective of this study was to investigate possible indicators of optimum seed maturity in guayule. The optimum harvest maturity time for guayule was studied by comparing quality parameters at different times after flowering. Heat units expressed as growing degree-days after flowering were calculated and related to seed development stages and quality. Seed quality at different stages of development was assessed by germination, capitulum dry mass, 1000 seed mass, and percentage of filled seeds. The maximum seed quality was recorded at 329 growing degree-days (GDD). This was 28 days from time of flowering. At this date, the moisture content of the capitulum was 48% on a wet basis and the colour was comparable to cinnamon (Code 165C) on the Royal Horticultural Society (R.H.S.) standard colour chart. Of all the parameters GDD, 1000 seed mass, and percentage of filled seeds provided a more rapid and reliable measure of optimum seed maturity. Colour identification can be used as an additional indicator. (C) 2005 Elsevier B.V. All rights reserved.

Palm kernel meal in broiler diets: effect on chicken performance and health

An increase in the production of palm kernel meal (PKM) coupled with the concern for continued availability of conventional feedstuffs in some parts of the world has led to research to establish the maximum inclusion level of palm kernel meal in broiler diets. The results suggested that palm kernel meal has no anti-nutritional properties and thus its inclusion is safe up to at least 40% in the diet, provided the diet is balanced in amino acids and metabolisable energy. Although feed digestibility is decreased due to high dietary fibre when PKM is included in the diet, the feed intake is increased. This makes total digestible nutrient intake relatively high. beta-mannan is the main component of palm kernel meal non-starch polysaccharide (NSP). Both mannose and manno-oligosaccharides have been reported to act as prebiotics. The inclusion of palm kernel meal in the diet improves the immune system of birds and reduces pathogenic bacteria and increases the population of nonpathogenic bacteria in the intestine. These two benefits should be considered as strong recommendations for using palm kernel meal in broiler diets, particularly in palm kernel meal producing countries, not only for increasing bird productivity but also to improve chicken health. Selective enzyme addition increases feed efficiency and digestibility as well as decreasing the moisture content of faeces.

The hydration of paper studied with solid-state magnetisation-exchange H-1 NMR spectroscopy

The wide-line H-1 nuclear magnetic resonance (NMR) spectrum of paper in equilibrium with ambient humidity consists of super-imposed relatively broad and narrow lines. The narrower line is of the order of 2 kHz wide at half the maximum height, while the broader line is of the order of 40 kHz in width at half height. On the basis of these line widths, the narrow line is assigned to water sorbed to the paper, and the broad line to the polymeric constituents of the paper. It was not possible to distinguish between the various polymeric components of paper contributing to the H-1 NMR spectra. A modified Goldman-Shen pulse sequence was used to generate a spatial magnetisation gradient between the polymer and water phases. The exchange of magnetisation between protons associated with water and those associated with the macromolecules in paper was observed. The exchange of magnetisation is discussed within a heat transfer model for homonuclear dipolar coupling, with exchange being characterised by a spin-diffusion coefficient. Consideration of the magnitude of the initial rate of the exchange process and estimates of the spin-spin relaxation times based on H-1 line widths indicate that some water must exist in a sufficiently immobile state as to allow homonuclear dipolar interactions between adjacent polymer and water protons. Thus, water sorbed onto paper must exist in at least two states in mass exchange with each other. This observation allows certain conclusions to be drawn about the ratio of free/bound water as a function of moisture content and the dispersal of water within the polymer matrix.

Drying process of microcrystalline cellulose studied by attenuated total reflection IR spectroscopy with two-dimensional correlation spectroscopy and principal component analysis

Molecular interactions between microcrystalline cellulose (MCC) and water were investigated by attenuated total reflection infrared (ATR/IR) spectroscopy. Moisture-content-dependent IR spectra during a drying process of wet MCC were measured. In order to distinguish overlapping O–H stretching bands arising from both cellulose and water, principal component analysis (PCA) and, generalized two-dimensional correlation spectroscopy (2DCOS) and second derivative analysis were applied to the obtained spectra. Four typical drying stages were clearly separated by PCA, and spectral variations in each stage were analyzed by 2DCOS. In the drying time range of 0–41 min, a decrease in the broad band around 3390 cm−1 was observed, indicating that bulk water was evaporated. In the drying time range of 49–195 min, decreases in the bands at 3412, 3344 and 3286 cm−1 assigned to the O6H6cdots, three dots, centeredO3′ interchain hydrogen bonds (H-bonds), the O3H3cdots, three dots, centeredO5 intrachain H-bonds and the H-bonds in Iβ phase in MCC, respectively, were observed. The result of the second derivative analysis suggests that water molecules mainly interact with the O6H6cdots, three dots, centeredO3′ interchain H-bonds. Thus, the H-bonding network in MCC is stabilized by H-bonds between OH groups constructing O6H6cdots, three dots, centeredO3′ interchain H-bonds and water, and the removal of the water molecules induces changes in the H-bonding network in MCC.

High-pressure adsorption of methane and carbon dioxide on coal

Adsorption isotherms of methane and carbon dioxide on two kinds of Australian coals have been measured at three temperatures up to pressures of 20 MPa. The adsorption behavior is described by three isotherm equations: extended three-parameter, Langmuir, and Toth. Among these, the Toth equation is found to be the most suitable, yielding the most realistic values of pore volume of the coals and the adsorbed phase density. Also, the surface area of coals obtained from CO2 adsorption at 273 K is found to be the meaningful parameter which captures the CO2 adsorption capacity. A maximum in the excess amount adsorbed of each gas appears at a lower pressure with a decrease in temperature. For carbon dioxide, after the appearance of the maximum, an inflection point in the excess amount adsorbed is observed close to the critical density at each temperature, indicating that the decrease in the gas-phase density change with pressure influences the behavior of the excess amount adsorbed. In the context of CO2 sequestration, it is found that CO2 injection pressures of lower than 10 MPa may be desirable for the CH4 recovery process and CO2-holding capacity.

Applications of the cyclone stickiness test for characterization of stickiness in food powders

The cyclone stickiness test (CST) technique was applied to measure the stickiness temperature and relative humidity of whey, honey, and apple juice powders. A moisture sorption isotherm study was conducted to analyze the surface moisture content of whey powder. The glass transition temperatures of the sample powder were analyzed using differential scanning calorimetry (DSC). The stickiness results of these products were found within 20 degrees C above their surface glass transition temperatures, which is well within the normal temperature range for glass transition in general. The results obtained by the CST technique were found consistent with DSC values.

Fluidization characteristics of moist food particles

Changes in fluidization behaviour of green peas particulates with change in moisture content during drying were investigated using a fluidized bed dryer. All drying experiments were conducted at 50 + 2 0C and 13 + 2 % RH using a heat pump dehumidifier system. Fluidization experiments were undertaken for the bedheights of 100, 80, 60 and 40 mm and at 10 moisture content levels. Fluidization behaviour was best fitted to the linear model of Umf = A + B m. A generalized model was also formulated using the height variation. Also generalized equation and Ergun equation was used to compare minimum fluidization velocity. Copyright ©2006 The Berkeley Electronic Press. All rights reserved.

Compositional analysis of teas from Australian supermarkets

Caffeine, total amino acids, water extract and moisture content are considered to be quality indicators for leaf teas and teabags. These analyses were examined in 20 leaf teas and 36 teabags sampled from Australian supermarkets. About 70% of the analysed samples showed a moisture content higher than Vie maximum accepted level, 6.5%, for tea storage and marketing by the tea industries and traders. Water appropriate extract of 15 samples out of 36 teabags was lower than that of the teas without teabags, which indicates that the quality of the paper used for teabags needs to be evaluated. Moreover, one of the black leaf tea samples was found to have a water extract below the lower limit of international standards. Four green and black teas of the same brand, claimed to contain less than 3% caffeine, were found to have 3-4%, the same as the other samples analysed in this study. The mean total contents of amino acids were 2.50% and 1.76% in black leaf teas and the teabags, respectively, whereas they were 3.44% and 2.28% in green leaf teas and the teabags, respectively. Furthermore, the weights of 28 teabags out of 36 samples were found to lie outside of the proposed +/- 2% variation accepted by the tea industries and traders, and 4 samples showed even larger variation, 10% being out of the proposed weights. This investigation also showed that the solubility of caffeine and water extract was affected by the permeability of teabags, whereas total amino acids were very variable. These results suggest that an efficient and practical quality control system for both imported and Australian-made teas in the Australian supermarkets should be developed, implemented and enforced. Chemical analysis should be a part of the system for establishing an objective assessment for the quality control. (c) 2004 Elsevier Ltd. All rights reserved.

EFFECT OF FORMULATION ON PHYSICO-CHEMICAL PROPERTIES, WATER STATUS AND STABILITY OF PASTA, TOMATO SAUCE AND READY TO EAT PASTA MEALS

Ready to eat pasta meals are an important segment of convenience food, but these products are subjected to significant changes in physico-chemical properties during storage, which reduce their acceptability at the time of consumption. A deep understanding of the properties of the single phases, their dependence upon formulation, and the changes they undergo during storage is very important to intelligently intervene on products properties to improve their quality at the time of consumer’s consumption. This work has focused on the effect of formulation on physico-chemical properties of pasta and tomato sauce with a special focus on mechanical/rheological attributes and water status. Variable considered in pasta formulation were gluten, glycerol and moisture content and their effect was studied in both freshly cooked or shelf-stable cooked pasta. The effect of multiple hydrocolloids (at different levels) was considered in the case of tomato sauce. In the case of pasta, it was found that water content was indeed a very important variable in defying pasta mechanical properties and water status. Higher moisture contents in pasta resulted in softer samples and reduced the changes in physico-chemical parameters during storage. Glycerol was found to favor water uptake and to soften the pasta matrix, acting as plasticizer and increasing molecular mobility. The addition of gluten hardened pasta but did not affect the water status. The combination of higher amount of gluten (15%, g gluten / 100 g product) with higher moisture content (59-65%, g water / 100 g product) were found to minimize the physico-chemical changes occurring in RTE pasta meals during storage, improving quality at longer storage times. Hydrocolloids added into tomato sauce modulated its mechanical attributes and water status in very different manner, depending on hydrocolloid type and concentration. This may allow to produce tomato sauce for different applications and that are expected to have different performance if placed in contact with pasta in a RTE meal. Future work should include an investigation of how the interaction between the two phases (pasta and sauce) can be modulated and controlled by controlling the properties of the single phases with the goal of obtaining highly acceptable products also at longer storage times.

Soredial dispersal from individual soralia in the lichen Hypogymnia physodes (L.) Nyl.

Soredial dispersal from individual soralia of Hypogymnia physodes (L.) Nyl. was studied in the field under natural conditions and by exposing the soralia to an electric fan. Individual soralia were placed on the adhesive surface of dust particle collectors which were pinned to vertical boards in the field. The majority of soredia that were deposited on the adhesive strips during the experiments were found within 1 cm of the source soralium. Deposition was studied over 6 successive days under natural conditions. Significantly fewer soredia were deposited from soralia after removal of mature accumulations and from soralia taken from moist thalli compared with soralia from air dry thalli. In addition, there was a decline in soredial deposition over the 6 days. The influence of wind speed and initial thallus moisture content on soredial deposition over short intervals of time was studied using an electric fan. More soredia and larger soredial clusters were deposited from air dry than moist soralia at all wind speeds. Variation in wind speed between 4 and 9 m/sec had little effect on soredial deposition. Deposition of soredia was also studied using the fan over successive 5-min intervals. Large numbers of soredia were deposited during the first 5-min period. Deposition then declined but recovered after about four 5-min periods. In all experiments there were differences between individual soralia in total numbers of soredia deposited and in the pattern of deposition over time. These results suggest (1) soredia accumulate on soralia and these deposits may be gradually or rapidly depleted in the field, (2) that after the release of soredial accumulations some newly exposed soredia may be rapidly dispersed, (3) a high initial thallus moisture content inhibits soredial release and (4) variation in wind speed is less important than moisture in influencing soredial deposition. The results may help to explain the intermittent pattern of soredial deposition and the poor correlations between deposition and climatic factors observed previously in the field. © 1992.

Chitosan-based spray-dried respirable powders for sustained delivery of terbutaline sulfate

In this study, we describe the preparation of highly dispersible dry powders for pulmonary drug delivery that display sustained drug release characteristics. Powders were prepared by spray-drying 30% v/v aqueous ethanol formulations containing terbutaline sulfate as a model drug, chitosan as a drug release modifier and leucine as an aerosolisation enhancer. The influence of chitosan molecular weight on the drug release profile was investigated by using low, medium and high molecular weight chitosan or combinations thereof. Following spray-drying, resultant powders were characterised using scanning electron microscopy, laser diffraction, tapped density analysis, differential scanning calorimetry and thermogravitational analysis. The in vitro aerosolisation performance and drug release profile were investigated using Multi-Stage Liquid Impinger analysis and modified USP II dissolution apparatus, respectively. The powders generated were of a suitable aerodynamic size for inhalation, had low moisture content and were amorphous in nature. The powders were highly dispersible, with emitted doses of over 90% and fine particle fractions of up to 82% of the total loaded dose, and mass median aerodynamic diameters of less than 2.5microm. A sustained drug release profile was observed during dissolution testing; increasing the molecular weight of the chitosan in the formulation increased the duration of drug release. (c)2007 Elsevier B.V. All rights reserved.

Amino acid-modified spray-dried powders with enhanced aerosolisation properties for pulmonary drug delivery

In this study, the amino acids arginine, aspartic acid, leucine, phenylalanine and threonine were investigated as 'dispersibility enhancers' in spray-dried powders for inhalation. Parameters such as spray-dried yield, tapped density, and Carr's Index were not predictive of aerosolisation performance. In addition, whilst the majority of amino acid-modified powders displayed suitable particle size distribution for pulmonary administration and potentially favourable low moisture content, in vitro particle deposition was only enhanced for the leucine-modified powder. In summary, leucine can be used to enhance the dispersibility and aerosolisation properties of spray-dried powders for pulmonary drug delivery. © 2007 Elsevier B.V. All rights reserved.

Improvement of bio-oil stability in wood pyrolysis process

Pyrolysis is one of several thermochemical technologies that convert solid biomass into more useful and valuable bio-fuels. Pyrolysis is thermal degradation in the complete or partial absence of oxygen. Under carefully controlled conditions, solid biomass can be converted to a liquid known as bie-oil in 75% yield on dry feed. Bio-oil can be used as a fuel but has the drawback of having a high level of oxygen due to the presence of a complex mixture of molecular fragments of cellulose, hemicellulose and lignin polymers. Also, bio-oil has a number of problems in use including high initial viscosity, instability resulting in increased viscosity or phase separation and high solids content. Much effort has been spent on upgrading bio-oil into a more usable liquid fuel, either by modifying the liquid or by major chemical and catalytic conversion to hydrocarbons. The overall primary objective was to improve oil stability by exploring different ways. The first was to detennine the effect of feed moisture content on bio-oil stability. The second method was to try to improve bio-oil stability by partially oxygenated pyrolysis. The third one was to improve stability by co-pyrolysis with methanol. The project was carried out on an existing laboratory pyrolysis reactor system, which works well with this project without redesign or modification too much. During the finishing stages of this project, it was found that the temperature of the condenser in the product collection system had a marked impact on pyrolysis liquid stability. This was discussed in this work and further recommendation given. The quantity of water coming from the feedstock and the pyrolysis reaction is important to liquid stability. In the present work the feedstock moisture content was varied and pyrolysis experiments were carried out over a range of temperatures. The quality of the bio-oil produced was measured as water content, initial viscosity and stability. The result showed that moderate (7.3-12.8 % moisture) feedstock moisture led to more stable bio-oil. One of drawbacks of bio-oil was its instability due to containing unstable oxygenated chemicals. Catalytic hydrotreatment of the oil and zeolite cracking of pyrolysis vapour were discllssed by many researchers, the processes were intended to eliminate oxygen in the bio-oil. In this work an alternative way oxygenated pyrolysis was introduced in order to reduce oil instability, which was intended to oxidise unstable oxygenated chemicals in the bio-oil. The results showed that liquid stability was improved by oxygen addition during the pyrolysis of beech wood at an optimum air factor of about 0.09-0.15. Methanol as a postproduction additive to bio-oil has been studied by many researchers and the most effective result came from adding methanol to oil just after production. Co-pyrolysis of spruce wood with methanol was undertaken in the present work and it was found that methanol improved liquid stability as a co-pyrolysis solvent but was no more effective than when used as a postproduction additive.