Simultaneous Drying and Separation of Composite Agricultural Material for Hay Processing

In composite agricultural materials such as grass, tee, medicinal plants; leaves and stems have a different drying time. By this behavior, after leaving the dryer, the stems may have greater moisture content than desired, while the leaves one minor, which can cause either the appearance of fungi or the collapse of the over-dried material. Taking into account that a lot of grass is dehydrated in forced air dryers, especially rotary drum dryers, this research was developed in order to establish conditions enabling to make a separation of the components during the drying process in order to provide a homogeneous product at the end. For this, a rotary dryer consisting of three concentric cylinders and a circular sieve aligned with the more internal cylinder was proposed; so that, once material enters into the dryer in the area of the inner cylinder, stems pass through sieve to the middle and then continue towards the external cylinder, while the leaves continue by the inner cylinder. For this project, a mixture of Ryegrass and White Clover was used. The characteristics of the components of a mixture were: Drying Rate in thin layer and in rotation, Bulk density, Projected Area, Terminal velocity, weight/Area Ratio, Flux through Rotary sieve. Three drying temperatures; 40°C, 60° C and 80° C, and three rotation speeds; 10 rpm, 20 rpm and 40 rpm were evaluated. It was found that the differences in drying time are the less at 80 °C when the dryer rotates at 40 rpm. Above this speed, the material adheres to the walls of the dryer or sieve and does not flow. According to the measurements of terminal velocity of stems and leaves of the components of the mixture, the speed of the air should be less than 1.5 m s-1 in the inner drum for the leaves and less than 4.5 m s-1 in middle and outer drums for stems, in such way that only the rotational movement of the dryer moves the material and achieves a greater residence time. In other hand, the best rotary sieve separation efficiencies were achieved when the material is dry, but the results are good in all the moisture contents. The best rotary speed of sieve is within the critical rotational speed, i.e. 20 rpm. However, the rotational speed of the dryer, including the sieve in line with the inner cylinder should be 10 rpm or less in order to achieve the greatest residence times of the material inside the dryer and the best agitation through the use of lifting flights. With a finite element analysis of a dryer prototype, using an air flow allowing speeds of air already stated, I was found that the best performance occurs when, through a cover, air enters the dryer front of the Middle cylinder and when the inner cylinder is formed in its entirety through a sieve. This way, air flows in almost equal amounts by both the middle and external cylinders, while part of the air in the Middle cylinder passes through the sieve towards the inner cylinder. With this, leaves do not adhere to the sieve and flow along drier, thanks to the rotating movement of the drums and the showering caused by the lifting flights. In these conditions, the differences in drying time are reduced to 60 minutes, but the residence time is higher for the stems than for leaves, therefore the components of the mixture of grass run out of the dryer with the same desired moisture content.

Degradation of atrazine and isoproturon in surface and sub-surface soil materials undergoing different moisture and aeration conditions

The influence of different moisture and aeration conditions on the degradation of atrazine and isoproturon was investigated in environmental samples aseptically collected from surface and sub-surface zones of agricultural land. The materials were maintained at two moisture contents corresponding to just above field capacity or 90% of field capacity. Another two groups of samples were adjusted with water to above field capacity, and, at zero time, exposed to drying-rewetting cycles. Atrazine was more persistent (t(1/2) = 22-3S days) than isoproturon (t(1/2) = 5-17 days) in samples maintained at constant moisture conditions. The rate of degradation for both herbicides was higher in samples maintained at a moisture content of 90% of field capacity than in samples with higher moisture contents. The reduction in moisture content in samples undergoing desiccation from above field capacity to much lower than field capacity enhanced the degradation of isoproturon (t(1/2) = 9-12 days) but reduced the rate of atrazine degradation (t(1/2) = 23-35-days). This demonstrates the variability between different micro-organisms in their susceptibility to desiccation. Under anaerobic conditions generated in anaerobic jars, atrazine degraded much more rapidly than isoproturon in materials taken from three soil profiles (0-250 cm depth). It is suggested that some specific micro-organisms are able to survive and degrade herbicide under severe conditions of desiccation. (C) 2004 Society of Chemical Industry.

The impact of fallowing and green manuring on soil conditions and the growth of sugarcane

There are currently concerns within some sugar industries that long-term monoculture has led to soil degradation and consequent yield decline. An investigation was conducted in Swaziland to assess the effects of fallowing and green manuring practices, over a seven-month period, on sugarcane yields and the physical properties of a poorly draining clay soil. In the subsequent first sugarcane crop after planting, yields were improved from 129 t ha(-1) under continuous sugarcane to 141-144 t ha(-1) after fallowing and green manuring, but there were no significant responses in the first and second ratoon crops. Also, in the first crop after planting, root length index increased from 3.5 km m(-2) under continuous sugarcane to 5.2-6.8 km m(-2) after fallowing, and improved rooting was still evident in the first ratoon crop where there had been soil drying during the fallow period. Soil bulk density, total porosity and water-holding capacity were not affected by the fallowing practices. However, air-filled porosity increased from 11% under continuous sugarcane to 16% after fallowing, and steady state ponded infiltration rates were increased from 0.61 mm h(-1) to 1.34 mm h(-1), but these improvements were no longer evident after a year back under sugarcane. Levels of soil organic matter were reduced in all cases, probably as a result of the tillage operations involved. In the plant crop, root length was well correlated with air-filled porosity, indicating the importance of improving belowground air supply for crop production on poorly draining clay soils.

Effect of culture medium and cryoprotectants on the growth and survival of probiotic lactobacilli during freeze drying

To investigate the effects of the medium and cryoprotective agents used on the growth and survival of Lactobacillus plantarum and Lactobacillus rhamnosus GG during freeze drying. A complex medium was developed consisting primarily of glucose, yeast extract and vegetable-derived peptone. Trehalose, sucrose and sorbitol were examined for their ability to protect the cells during freeze drying. Using standardized amount of cells and the optimized freeze drying media, the effect of the growth medium on cell survival during freeze drying was investigated. The results showed that glucose and yeast extract were the most important growth factors, while sucrose offered better protection than trehalose and sorbitol during freeze drying. When the cells were grown under carbon limiting conditions, their survival during freeze drying was significantly decreased. A clear relationship was observed between cell growth and the ability of the cells to survive during the freeze drying process. The survival of probiotic strains during freeze drying was shown to be dependent on the cryoprotectant used and the growth medium.

Synthesis of novel hyperbranched polymers featuring oxazoline linear units and their application in fast-drying solvent-borne coating formulations

Novel acid-terminated hyperbranched polymers (HBPs) containing adipic acid and oxazoline monomers derived from oleic and linoleic acid have been synthesized via a bulk polymerization procedure. Branching was achieved as a consequence of an acid-catalyzed opening of the oxazoline ring to produce a trifunctional monomer in situ which delivered branching levels of >45% as determined by 1H and 13C NMR spectroscopy. The HBPs were soluble in common solvents, such as CHCl3, acetone, tetrahydrofuran, dimethylformamide, and dimethyl sulfoxide and were further functionalized by addition of citronellol to afford white-spirit soluble materials that could be used in coating formulations. During end group modification, a reduction in branching levels of the HBPs (down to 12–24%) was observed, predominantly on account of oxazoline ring reformation and trans-esterification processes under the reaction conditions used. In comparison to commercial alkyd resin paint coatings, formulations of the citronellol-functionalized hyperbranched materials blended with a commercial alkyd resin exhibited dramatic decreases of the blend viscosity when the HBP content was increased. The curing characteristics of the HBP/alkyd blend formulations were studied by dynamic mechanical analysis which revealed that the new coatings cured more quickly and produced tougher materials than otherwise identical coatings prepared from only the commercial alkyd resins.

Stability of probiotic Lactobacillus plantarum in dry microcapsules under accelerated storage conditions

This study investigated the stability of freeze dried and fluid bed dried alginate microcapsules coated with chitosan containing model probiotic bacteria, Lactobacillus plantarum, during storage for up to 45 days at different water activities (0.11, 0.23, 0.40 and 0.70) and temperatures (4, 30 and 37 °C). The loss in cell viability was around 0.8 log in the case of fluid bed drying and around 1.3 in the case of freeze drying, with the former method resulting in dried capsules of smaller size (~ 1 mm vs 1.3 mm), more irregular shape, and with a rougher surface. In both cases, the water activity and water content were less than 0.25 and 10% w/w, respectively, which favours high storage stability. The storage stability studies demonstrated that as the water activity and temperature decreased the survival of the dried encapsulated cells increased. Considerably better survival was observed for fluid bed dried encapsulated cells compared to freeze dried encapsulated cells and freeze dried free cells with 10% sucrose (control), and in some cases, e.g. at 4 and 30 °C at water activities of 0.11, 0.23 and 0.40, there was more than 1 log difference after 45 days, with concentrations higher than 108 CFU/g after 45 days of storage. The results indicate that fluid bed drying is an effective and efficient manufacturing method to produce probiotic containing capsules with enhanced storage stability.

Physical properties of goat milk powder with soy lecithin added before spray drying

P>In this study, physical characteristics of goat milk powder produced with the addition of soy lecithin at levels of 0 (control), 0.4, 0.8 and 1.0 g lecithin/100 g of total solids in concentrated milk before the spray drying process were investigated. Goat milk was pasteurised, concentrated at 40% of total solids, spray dried and packed in plastic bags under vaccum conditions. Lecithin addition decreased the wetting time of milk powders, although no influence was observed on dispersibility, water sorption, water activity and particle size distribution of the powders. Powders with higher levels of lecithin showed significantly lower brightness, with a greater intensity of yellow colour. It was concluded that lecithin addition before spray drying process at the minimal proportion in concentrated milk of 0.4 g lecithin/100 g of total solids in concentrated milk is useful for achieving more rapid wetting time of goat milk powder.

Optimization of osmotic dehydration of papaya followed by air-drying

FERNANDES, Fabiano A. N. et al. Optimization of Osmotic Dehydration of Papaya of followed by air-drying. Food Research Internation, v. 39, p. 492-498, 2006.

Gelatin microparticles containing propolis obtained by spray-drying technique: preparation and characterization

Gelatin microparticles containing propolis extractive solution (PES) were prepared by spray-drying technique. The optimization of the spray-drying operating conditions and the proportions of gelatin and mannitol were investigated. Regular particle morphology was obtained when mannitol was used, whereas mannitol absence produced a substantial number of coalesced and agglomerated microparticles. Microparticles had a mean diameter of 2.70 mum without mannitol and 2.50 mum with mannitol. The entrapment efficiency for propolis of the microparticles was upto 41 % without mannitol and 39% with mannitol. The microencapsulation by spray-drying technique maintained the activity of propolis against Staphylococcus aureus. These gelatin microparticles containing propolis would be useful for developing intermediary or eventual propolis dosage form without the PES' strong and unpleasant taste, aromatic odour, and presence of ethanol. (C) 2003 Elsevier B.V. All rights reserved.

Air-drying of fresh and osmotically pre-treated pineapple slices: Fixed air temperature versus fixed slice temperature drying kinetics

In this investigation, the air drying characteristics of fresh and osmotically pre-treated pineapple slices in a tray dryer were studied under different operating conditions. The air velocity varied from 1.5 to 2.5 m/s and the air temperature from 40 to 70 degreesC. The analytical solution of the second Fick's law for an infinite slab was used to calculate effective diffusion coefficients and their temperature dependence could be well represented by an Arrhenius-type equation. Comparison of the results showed that the diffusion coefficients were lower for the pre-treated fruit. By means of automatic control, it was possible to obtain drying curves under conditions of constant product temperature, which showed to be an alternative to reduce the drying time of pineapple slices.

Factors affecting fish diversity and abundance in drying ponds and lagoons in the upper Paraná River basin, Brazil

Monthly samples were taken from April 1992 to March 1993 of fish assemblages present in six permanent lagoons and four ponds, fragmented from them during the drought period and during the terminal phases of desiccation, to evaluate changes in their diversity, abundance and dominance. Their relationships with hydrological and environment conditions were examined. A total of 63 fish species were identified. Species composition and abiotic factors were heterogeneous among the different water bodies. The proportion of piscivores and oxygen concentration were the determining factors for structuring the assemblages. The impact of piscivory upon fish diversity was neutral at the beginning and negative at the end of the dry season. In the terminal phase of desiccation, diversity was higher in ponds that contained a moderate proportion of piscivores than in these containing a higher proportion.

Optimization of annatto (Bixa orellana L.) drying in fixed bed

ABSTRACT: The drying of annatto seeds (Bixa orellana L.), red piave cultivate, was studied in a fixed bed dryer. The best conditions were estimated to minimize the loss of coloring and to obtain final moisture of the seeds in appropriate levels to its conservation and maintenance of quality. The quantification of the influence of entrance variables in the final contents of bixin and moisture seeds and the identification of the optimal point was performed through the techniques of factorial design, response surfaces methodology, canonical analysis and desirability function. It was verified that the final moisture of the seeds may be estimated by a second-order polynomial model and that the final content of bixin is only significantly influenced by the time of drying being described properly by a linear model, for the seeds used in this study.

Freeze-drying for microencapsulation of turmeric oleoresin using modified starch and gelatin

The aims of this study were to assess the turmeric oleoresin microencapsulation by freeze-drying with modified starch/gelatin and to evaluate its stability during storage at different temperatures and light. Encapsulated turmeric oleoresin w stored at −20, 25 and 60C, in the absence of light, and at 25C in the presence of light, and analyzed over a period of 6 weeks for curcumin and total phenolic contents and color. The different concentrations of wall material showed no significant effect on the curcumin retention. The best conditions for microencapsulation of turmeric oleoresin were: wall material composed of 30 g/100 g of modified starch + 1 g/100 g gelatin and mechanical homogenization. Encapsulated material was more stable during storage at −20C and less stable at 25C in the presence of light.

Processing of Apeiba tibourbou Aubl. Extract Via Spray Drying

The effects of drying air inlet temperature (IT) and concentration of Aerosil 200 (C-A) on several properties of spray-dried Apeiba tibourbou extracts were investigated following a 3(2) full factorial design. Powder recovery varied from 9.83 to 46.95% and dried products showed moisture contents below 7%. Although the spray-dried products lost some of their polyphenols, they still present excellent antioxidant activity, opening perspectives for its use to medicinal purpose. C-A exerted a key role on the properties of spray-dried extracts, while IT did not present a significative influence. Aerosil (R) 200 proved to be an interesting alternative as an excipient for the drying of the herbal extract, even at intermediate concentrations such as 15%. The best combination of conditions to use for obtaining dry A. tibourbou extracts with adequate physicochemical and functional properties involves an IT of 100 degrees C and a C-A of 15%.

Spray drying microencapsulation of Lippia sidoides extracts in carbohydrate blends

The microencapsulation of Lippia sidoides extracts in blends of carbohydrates was investigated. The extraction conditions were determined through a 2(2) factorial design. The effects of the plant:solvent ratio (A - 7.5:100 and 15:100 m/m) and the extraction time (B - 30 and 90 min) on thymol content of extractive solutions were evaluated, using a 2:1 (v/v) of ethanol:water at a temperature of 50 degrees C, as a solvent system. The selected extract was subjected to spray drying. Blends of maltodextrin and gum arabic at different proportions (4:1; 3:2; 2:3; 0:1) (m/m) were used as encapsulating material. The protective effects of the maltodextrin and gum arabic blends were evaluated by determination of the thymol retention in the dried product, which ranged from 70.2 to 84.2% (related to the content in the extractive solution). An increase in the gum arabic to maltodextrin (DE10) ratio has positive effect on thymol retention. L. sidoides extracts and spray-dried products showed antifungal activity against tested fungal strains (Candida albicans - ATCC 64548, Candida glabrata - ATCC 90030, Candida krusei - ATCC 6258, and Candida parapsilosis - ATCC 22019), evidencing their potential as a natural antifungal agent for medicinal, food, and cosmeceutical purposes. (C) 2012 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.