Effect Of Ultrasonic Pretreatment Research Articles

Effect of Ultrasonic Pre-Treatment on the Reverse Flotation of Kaolinite From Bauxite

ABSTRACT Cationic reverse flotation of kaolinite from bauxite is an alternative to adequate high silica bauxites to the specifications of the Bayer process. However, the presence of clay minerals influences the slurries rheology decreasing the flotation performance. The objective of this work was to investigate the use of ultrasonic pre-treatment on kaolinite flotation and contrast it with the traditionally used chemical dispersant. Two bauxite samples were characterized in terms of chemical and mineralogical composition, as well as particle size distribution. Flotation was accomplished after conditioning with sodium polyacrylate and/or pre-treatment in ultrasound. Determinations of viscosity, sedimentation yield, and screening followed by the analysis of available alumina and reactive silica were also conducted. By increasing the concentration of solids to more than 20 wt.%, the slurry behavior changed from a Newtonian to a non-Newtonian behavior, the viscosity increased, and the flotation performance decreased. The use of chemical dispersant and ultrasonic pre-treatment increased the flotation performance. The ultrasound had a more marked effect in slurries with higher concentrations of solids. This result is related to the synergic effect of particle dispersion and reduction of the slime coating promoted by kaolinite onto gibbsite particles.

Effect of ultrasonic pretreatment on the structure and emulsion stability of epigallocatechin-3-gallate and rice bran protein complex

To enhance the emulsion stability of RBP, the mixed solution of epigallocatechin-3-gallate (EGCG) and rice bran protein (RBP) was pretreated by increasing ultrasonic power (200–500 W). Ultrasonic pretreatment decreased the α-helix/β-sheet ratio (P < 0.05), and caused red-shift absorption peaks of intrinsic fluorescence and UV absorption spectroscopy of EGCG-RBP complex. With increasing ultrasonic power, combined phenol content, particle size, absolute value of ζ-potential, free –SH content, and surface hydrophobicity of EGCG-RBP complex initially rose, and subsequently dropped (P < 0.05). Compared with the EGCG-RBP complex without ultrasonic pretreatment, emulsifying activity index increased from 37.68 m2/g to 42.51 m2/g, and emulsion stability index increased from 123.00 min to 326.43 min as ultrasonic power was 425 W. The centrifugal stability constant, emulsion separation rate, and emulsion particle size initially dropped, and subsequently rose with increasing ultrasonic power. The emulsion stability of EGCG-RBP complex was correlated with particle size, absolute value of ζ-potential, α-helix/β-sheet ratio, free –SH content, and surface hydrophobicity (P < 0.05). Overall, ultrasonic pretreatment enhanced the EGCG-RBP interaction by regulating the absolute value of ζ-potential, flexibility and surface hydrophobicity of EGCG-RBP complex, thus improving emulsion stability, which provided a theoretical foundation for expanding the application of RBP in foodstuffs.

Effect of ultrasonic pretreatment on the flocs characteristics in the flocculation filtration process of coal slurry water

The enhancement of ultrasonic pretreatment on the flocculation filtration of coal slurry water has been reported. The structural characteristics of flocs are critical parameters in the flocculation and filtration process. In this paper, the effect of ultrasonic pretreatment on the flocs' characteristics during flocculation and filtration was investigated. The flocs size, number, strength, and fractal dimension in the microstate were characterized through a polarized light microscope, PVM, and FBRM. The changes in flocs characteristics on the filter cake's pore structure and moisture distribution were analyzed using L-F NMR. The results showed that the optimal condition was an ultrasonic frequency of 30 KHz, ultrasonic time of 3 min, and the dosage of cationic polyacrylamide (CPAM) with ionicity of 60 at 50 g/t, under which the filtration rate was 597.42 mL·(m2s)−1 and the moisture content of the filter cake was 27.03 %. Ultrasonic pretreatment increased the flocs' size, with a decrease in the proportion of small flocs and an increase in the proportion of medium and large flocs, mainly medium flocs. The increase in the fractal dimension and strength of the flocs structure made the filter cake deformed less under pressure, formed a porous skeleton structure, and increased the total porosity of the filter cake, with the most significant variation in mesopores. Moreover, ultrasonic pretreatment could decrease the proportion of adsorbed and bound water while increasing the proportion of free water and effectively reducing the filter cake's moisture content. This study revealed the essential relationship between floc characteristics and flocculation filtration efficiency, filter cake pore structure, and moisture distribution and provided a new perspective for exploring the application mechanism of ultrasonic technology in enhancing flocculation filtration performance.

Effects of ultrasonic pretreatment and drying approaches on the drying kinetics and rehydration of sprouted mung beans

AbstractSprouting is one of the most traditional methods used to decrease most of the antinutritional elements in legumes. The assistance of ultrasound appears to enhance the drying step of the sprouted legumes. The aim of this study was to examine the influence of ultrasound pretreatment and drying methods (hot‐air and infrared) on the drying time, mass transfer kinetic, effective moisture diffusivity (Deff), and rehydration ratio of sprouted mung beans. The ultrasound process (40 kHz and 150 W) was performed in an ultrasonic bath for 0, 5, 10, 15, and 20 min. The results showed that the ultrasonic pretreatment increased the moisture diffusion capacity (higher moisture loss) and reduced the drying time of sprouted mung beans. Also, the drying time of samples in the infrared dryer was significantly less than that in the hot‐air dryer (p &lt; .05). The Deff determined by Fick's second law was varied from 1.36 × 10−10 to 1.88 × 10−10 m2 s−1, and from 1.18 × 10−9 to 1.85 × 10−9 m2 s−1, for samples dried in hot‐air and infrared dryers, respectively. Comparing the coefficient of determination (r), sum of squared error (SSE), and root mean squared error (RMSE) values of 10 models, it was concluded that the Midilli model represents the drying characteristics of sprouted mung beans better than the others. The rehydration ratio of dried samples in hot‐air and infrared dryers increased when the ultrasound pretreatment time was increased. In general, the use of ultrasound pretreatment (about 20 min) and an infrared dryer is a promising drying technique for sprouted mung beans with higher mass transfer and a shorter drying time.

Optimum drying conditions for ginger (Zingiber officinale Roscoe) based on time, energy consumption and physicochemical quality

The effect of ultrasonic pre-treatment on moisture removal characteristics of ginger in a convective dryer was investigated. The slabs were dried by practicing sonication durations of 0, 15 and 30 min at different levels of the air temperature and velocity. Following increasing the sonication duration and air temperature, required time and energy to dehydrate the samples were decreased. The pre-treatment played important role in improving rehydration capability and surface color retention in the dried gingers. Content of the main volatile component (α-Zingiberene) was not influenced by the sonication. Mean values for the phenolic contents and antioxidant activity at sonication duration of 0, 15 and 30 min were determined to be 18.93, 18.15 and 17.49 GAE/g dry matter and 83.57, 78.33 and 74.58 %, respectively. The desired values for the temperature, velocity and sonication duration were revealed to be about 66 °C, 3 m/s and 20 min, respectively.

Nanocrystallite Zeolite BEA for Regioselective and Continuous Acetyl Functionalization of Anisole Using Acetic Anhydride: Catalyst Deactivation Studies.

Ultrasonic pretreatment of gel composition followed by hydrothermal synthesis produces the nanocrystallite zeolite beta (ZB) with crystal sizes of 10.3, 22.6, and 9.1 nm for ZB-1, ZB-2, and ZB-3, respectively. The effect of ultrasonic pretreatment and the (SiO2/Al2O3) ratio of gel composition on physical, textural properties, and also on the catalytic activity of ZB catalysts with increasing time on stream (TOS) was investigated. The specific surface area and mesopore volume for ZB-1, ZB-2, and ZB-3 are 438, 380, and 429 m2/g and 0.17, 0.05, and 0.14 cm3/g, respectively. The activity studies of ZB-1 and ZB-3 catalysts were confirmed that the anisole conversion initially increased with TOS until it attained the maximum value and then started decreasing further with TOS due to the deactivation of the catalyst caused by the strong interaction of the product with the acidic sites in the mesopore region. However, in the case of ZB-2, the anisole conversion (>45%) was sustained for a longer TOS due to its smaller particle size, low mesopore volume, and more acidic sites in the micropore volume that are inclusively made for retardation in the catlytic deactivation rate. The CHNS and TGA analysis of the spent catalysts confirm that ZB-1 and ZB-3 catalysts are susceptible for a significant coke formation attributed due to strong product retention in their large mesopore volume, which lead to the catalytic deactivation.

Quantitative proteomics provides new insights into the mechanism of improving rehydration of egg white powder by ultrasonic pretreatment

Poor rehydration is one of the key factors affecting the functional properties of egg white powder (EWP). Reducing rehydrated precipitates is important for the processing and application of EWP. In this study, effects of ultrasonic pretreatment on the physicochemical and functional properties of EWP rehydration solutions were studied with the aim of revealing the mechanism of ultrasonic pretreatment to improve rehydration. Compared with freeze-dried EWP (FD) and spray-dried EWP (SD), the percentage of ultrasonic pretreated FD (UFD) and ultrasonic pretreated SD (USD) rehydrated precipitates decreased by 13.0 % and 5.6 %, respectively, after ultrasonic pretreatment (0.25 W/mL for 10 min); and the average particle sizes of UFD and USD solutions decreased by 22.5 % and 15.5 %, respectively. Fourier transform infrared spectroscopy showed that ultrasonic pretreatment caused higher β-sheet content in the protein secondary structure of UFD rehydrated precipitates (49.2 %). Quantitative proteomic analysis revealed a decrease in the abundance of major egg white proteins (ovalbumin, ovotransferrin, ovomucoid and ovomucin) in the rehydrated precipitates of UFD, except for lysozyme. It was also shown that lysozyme-centered aggregates were disrupted in the rehydrated precipitates of UFD. Our research suggests that ultrasonic pretreatment improves EWP rehydration by reducing the interactions between high abundance proteins as well as improving the solubility of high abundance proteins.

Effect of Ultrasonic Pretreatment on Yield and Properties of Essential Oil of Betel Leaf (Piper betle L.)

Effect of Ultrasonic Pretreatment on Yield and Properties of Essential Oil of Betel Leaf (Piper betle L.)

Characteristics of enzymolysis of silkworm pupa protein after tri-frequency ultrasonic pretreatment: kinetics, thermodynamics, structure and antioxidant changes.

As a by-product of the sericulture industry, the utilization rate of silkworm pupa resources is currently not high. Proteins are converted into bioactive peptides through enzymatic hydrolysis. Not only can it solve the utilization problem, but it also creates more valuable nutritional additives. Silkworm pupa protein (SPP) was pretreated with tri-frequency ultrasonic (22/28/40kHz). Effects of ultrasonic pretreatment on enzymolysis kinetics, enzymolysis thermodynamics, hydrolysate structure as well as hydrolysate antioxidant of SPP were investigated. Ultrasonic pretreatment significantly increased the hydrolysis efficiency, showing a 6.369% decrease in k m and a 16.746% increase in k A after ultrasonic action (p < 0.05). The SPP enzymolysis reaction followed a second-order rate kinetics model. Evaluation of enzymolysis thermodynamics revealed that Ultrasonic pretreatment markedly enhanced the SPP enzymolysis, leading to a 21.943% decrease in E a. Besides, Ultrasonic pretreatment significantly increased SPP hydrolysate's surface hydrophobicity, thermal stability, crystallinity, and antioxidant activities (DPPH radical scavenging activity, Fe2+ chelation ability, and reducing power). This study indicated that tri-frequency ultrasonic pretreatment could be an efficient approach to enhancing the enzymolysis and improving the functional properties of SPP. Therefore, tri-frequency ultrasound technology can be applied industrially to enhance enzyme reaction process.

Effect of Ultrasonic Pretreatment on the Far-Infrared Drying Process and Quality Characteristics of Licorice.

In this paper, the effects of different ultrasonic pretreatment processes on the far-infrared drying characteristics, quality indexes, and microstructure of licorice are evaluated. The results showed that ultrasonic pretreatment, combined with far-infrared drying, significantly reduced the drying time and moisture content of licorice compared with those of the control group. The highest total flavonoid content was obtained at an ultrasound power of 80 W. The total phenolic content (0.686 mg gallic acid equivalent/g) was higher than that in the control group, the increase was 19.4%, and its content was the highest at the sonication frequency of 20 kHz. The antioxidant capacity tended to increase and then decrease with the increase in sonication time, sonication power, and sonication frequency, and was the highest at 30 min of sonication. The soluble sugar content (31.490 mg glucose equivalent/g) was the highest at 30 kHz and 30 min. Observation of the microstructure revealed that the surface structure of the ultrasonic pretreated licorice slices changed significantly, forming more micropore channels, which facilitated the mass heat transfer during the drying process. In conclusion, ultrasonic pretreatment can significantly improve the quality of licorice tablets and significantly reduce the time required for subsequent drying. The combination of pretreatment parameters of 60 W ultrasonic power and 40 kHz ultrasonic frequency for 30 min was found to be an optimal combination of pretreatment parameters; therefore, this study may provide a technical reference for the industrialization of licorice drying.

Effect of Ultrasonic Pre-treatment on Cow dung Slurry with Sludge Water, Food Waste for Biogas Production in Anaerobic Digesters and Result Validation using Response Surface Methodology

Effect of Ultrasonic Pre-treatment on Cow dung Slurry with Sludge Water, Food Waste for Biogas Production in Anaerobic Digesters and Result Validation using Response Surface Methodology

Effect of ultrasonic pretreatment on the rheology and structure of grass pea (Lathyrus sativus L.) protein emulsion gels induced by transglutaminase.

In this study, emulsion gels were prepared by sonicated grass pea protein isolates (GPPI) at different ultrasonic amplitudes (25, 50 and 75%) and times (5, 10 and 20min). Formation of emulsion gels was induced by transglutaminase. Enzymatic gelation of emulsions stabilized by sonicated GPPI occurred in two stages. A relatively fast stage led to the formation of a weak gel which was followed by a slow stage that strongly reinforced the gel structure. Emulsion gels fabricated by sonicated GPPIs showed a homogeneous and uniform droplet distribution with higher elastic modulus compared to the native protein. A stiffer emulsion gel with a higher G' was formed after the protein was treated at 75% amplitude for 10min. After sonication of GPPI, the water holding capacity (WHC) of emulsion gels increased in accordance with the mechanical properties. Higher intermolecular cross-linking within the gel network increased the thermal stability of emulsion gels fabricated by sonicated GPPI. Although sonicated-GPPI emulsion gels clearly displayed homogenous microstructure in comparison to that made with native GPPI, the microstructures of these gels were nearly identical for all sonication amplitudes and times.

Effect of Ultrasonic Pretreatment on Radio Frequency Vacuum Drying Characteristics and Quality of Codonopsis pilosula Slices

In this paper, the effects of ultrasonic pretreatment on the drying kinetics, bioactive components (polysaccharides, total phenols, total flavonoids and antioxidant), qualitative characteristics (color index, lobetyolin and syringin) and microstructure of Codonopsis pilosula during radio frequency vacuum drying (RFVD) were studied. The average drying rate curve showed that the whole drying process could be divided into three stages: accelerating period, constant drying rate period and falling drying rate period. Deff values ranged from 6.61425 to 9.46745 × 10−8. Analysis of the drying rate constants revealed that different conditions of pretreatment were effective in increasing the drying rate. Ultrasonic pretreatment has a positive effect on the retention of polysaccharide content; low frequency favors retention of total phenols, flavonoids and syringin; and with the increase in ultrasonic time and ultrasonic power, the antioxidant capacity was higher than that without ultrasonic treatment. Ultrasonic pretreatment significantly improved color and microstructure. In summary, the pretreatment condition of ultrasonic frequency 20 kHz and power 60 W for 30 min is suitable, which provides a certain reference for the application of ultrasonic pretreatment technology in RFVD of Codonopsis pilosula slices.

Effect of ultrasonic pretreatment on tocochromanol and carotenoid biofortification in maize (Zea mays L.) seedlings.

Maize is a sought-after food crop because it is micronutrient-rich and affordable. It is an excellent source of carotenoids and tocochromanols. To investigate ways to enhance the micronutrients in maize, we grew maize seedlings with ultrasonic pretreatment to study the effect of ultrasound pretreatment on the biofortification of tocochromanols and carotenoids using high-performance liquid chromatography and real-time quantitative polymerase chain reaction. Four tocopherol isomers, three tocotrienol isomers and six carotenoid components were measured in maize seedlings. Compared with the untreated maize seedlings, carotenoid content increased and reached the highest level at 8min ultrasonic pretreatment (19.21 ± 0.44 μg g-1 fresh weight (FW)), but tocotrienol content evidently decreased. Tocopherol dropped at first but began to rise after 8min ultrasonic pretreatment (258.1 ± 6.4μg g-1 FW). In particular, zeaxanthin in maize seedlings doubled after pre-sonication, while lutein was boosted to 11.81 ± 0.20 μg g-1 FW. Ultrasonic pretreatment changed the predominant component of tocochromanols in maize seedlings from γ-tocotrienol to α-tocopherol, with the latter content being 1.3 times higher than in the untreated group. Up-regulation of key genes involved in the biosynthesis of tocopherols and carotenoids in maize seedlings occurred as a result of both 2min and 6min sonication pretreatment. In particular, Zm HPPD, Zm ZE, Zm ZDS and Zm MPBQ-MT could partly explain the changes in these phytochemicals. Wet ultrasonic pretreatment could increase tocopherol and carotenoid accumulation in maize seedlings but decrease tocotrienol synthesis. Some up-regulating genes are related to relevant syntheses, such as Zm HPPD, Zm ZE, Zm ZDS and Zm MPBQ-MT, which could influence the accumulation of tocopherols and carotenoids after ultrasonic pretreatment. © 2022 Society of Chemical Industry.

Ultrasonic pretreatment improved the physicochemical properties and riboflavin delivery ability of transglutaminase-catalyzed soy protein isolate gel

Soy protein isolate (SPI) was pre-treated with ultrasonic (400 W, 30–120 min) and then formed gel using transglutaminase (TG) method. Effects of ultrasonic pretreatment on structural, rheological and thermal properties as well as riboflavin delivery ability of SPI gel were investigated. Ultrasonic treatment significantly decreased the particle size, increased the free sulfhydryl content, enhanced the surface hydrophobicity, unfolded the conformational structure of SPI, facilitated the disulfide bonds and ε-(γ-glutamyl) lysine isopeptide bonds formation in transglutaminase-catalyzed soy protein isolate gel (TCSG). Ultrasonic pretreatment, particular for 60 min, significantly enhanced the gel strength, storage modulus, loss modulus, consistency and thermal stability, but decreased the flow behavior index of TCSG. The TCSG without ultrasonic pretreatment showed a non-uniform gel network with large and irregular pores. When applied ultrasonic pretreatment, more dense, uniform and stable gel networks were developed. The above physicochemical properties improvements inhibited the swelling behavior and markedly enhanced the riboflavin encapsulation efficiency and riboflavin delivery ability of TCSG, leading to 81% of riboflavin released in simulated intestinal environment. Therefore, ultrasonic pretreatment could be an efficient approach to improving the gel properties and nutrients delivery ability of SPI gel. • Ultrasonic decreased the particle size and increased the free SH content of SPI. • Ultrasonic enhanced the strength, G′, G″, consistency and thermal stability of TCSG. • US-TCSG samples showed more dense, uniform and stable gel networks. • The gel swelling behavior was inhibited and riboflavin delivery ability was enhanced. • 81% of riboflavin was released in simulated intestinal environment.

Effect of Ultrasonic Pretreatment on Flocculation Filtration of Low-Rank Coal Slurry.

The efficient filtration of low-rank coal (LRC) slurry was significantly beneficial to the production process of wet coal beneficiation. However, relatively few studies have been reported on novel pretreatment methods for the efficient filtration of LRC slurry. In this paper, the mechanism of ultrasonic pretreatment to promote flocculation and filtration of slurry was studied. The hydrophobic variation of the slurry surface was measured by contact angle and XPS. The flocculation properties of slurry were characterized using zeta potential and FBRM. The effects of filter cake porosity and ultrasonic pretreatment on slurry filtration resistance were calculated by L-F NMR and Darcy’s theory. The results showed that the ultrasonic pretreatment promoted the flocculation and filtration performance of LRC slurry, increased the filtration rate, and decreased the cake moisture content. Meanwhile, the contact angle of LRC increased significantly from 50.1° to 67.8° after ultrasonic pretreatment, and the surface tension of the filtrate decreased from 69.5 to 53.31 mN/m. Ultrasonic pretreatment reduced the absolute value of the zeta potential of coal slurry from 24.8 to 21.0 mV, and the average chord length of flocs increased from 5–10 μm to 25–30 μm, thus weakening the electrostatic repulsion between coals to promote floc formation. In addition, the pore tests and filtration theory calculations showed that the ultrasonic pretreatment significantly improved the permeability of the filter cake to water and reduced the resistance to slurry during filtration. In particular, the mesopore porosity increased by 9.18%, and the permeability increased by 2.937 × 108 m2. Therefore, this contributed to the reduction of slurry filtration resistance. This research provides an efficient method for promoting the efficient filtration of slurry.

Improvement of low-quality fine coal by ultrasonic hydrophobic flocculation

ABSTRACT In this study, the effect of ultrasonic pretreatment on hydrophobic flocculation of fine coal was investigated and named as ultrasonic hydrophobic flocculation (USHF) technique. First, it was found that the ultrasonic power of 150 W and the ultrasonic pretreatment time of 180 sec was required to achieve for more combustible and good-quality coal. Then, the effects of ultrasound on the hydrophobic flocculation of coal with kerosene as bridging liquid were investigated and optimum kerosene concentration value was obtained 4 g/dm3 under the experimental conditions. Also, it was found that a stirring speed of 750 rpm was sufficient to achieve the maximum combustible recovery and minimum ash content values of fine coal particles. The effects of sodium silicate, sodium hexametaphosphate, and sodium pyrophosphate used as inorganic dispersants on the ultrasonic hydrophobic flocculation of coal were also studied. Sodium silicate was more effective than other dispersants in the presence of kerosene. Thus, it was concluded that the ultrasonic pretreatment is an effective method for the beneficiation of fine particle coal. Coal with an ash content of 17.63% was enriched and clean coal was recovered with an ash content of 9.75% with the efficiency of 94.35% by ultrasonic hydrophobic flocculation technique.

Effect of ultrasonic pretreatment on drying kinetics and physio‐mechanical characteristics of peach slices

AbstractPeach, which is one of the most critical garden products in Iran has a lot of postharvest lesions. In this sense, processing the product would result in reducing the postharvest lesions. Recently, ultrasound waves have been widely applied as a new pretreatment method in drying food. Herein, we aim at investigating the effect of high power ultrasound pretreatment on the drying kinetics of peach slices. The effective moisture penetration coefficient, color changes and elastic modulus were investigated. The drying process was modeled using mathematical equations. The results showed that the ultrasound use as a pretreatment before drying reduces the drying time by up to 40%. The ultrasound treatment effect and the duration of their application on the color changes of the samples are not significant, and the reason for the color change is due to maillard reactions. The results of the effect of ultrasound pretreatment on the elastic modulus due to loading in the compression test showed that the application of pretreatment on the deformation of the samples is significant and reduced the modulus of elasticity by about 46%. The midilli model in different pretreatments, as compared to other models, had the best fitting with the experimental data. Moreover, the amount of effective diffusivity coefficient in the dried samples of peach slices, in different pretreatments, varies from 1.345 × 10−9 to 5.370 × 10−10 m2 s−1. In addition, it is worth mentioning that ultrasound pretreatment can be regarded as a promising approach. As far as food and agricultural products have typical structure and composition, ultrasound pretreatment application requires more through research.Practical ApplicationsAs compared to the untreated peach slices, a significant enhancement was witnessed in the ultrasound (US)‐treated slices. Herein, a new method is proposed, which results in producing slices with an improved quality. Generally, peach‐slice processing has been applied to get high‐quality products.

Change in some physical characteristics of ultrasound pre-treated corn during hot-air convection and vacuum drying

The objective of this study was to investigate the effect of ultrasound pre-treatment (50% US and 100% US-soaking), temperature (80, 90 and 100 ᵒC) and dryer type (hot-air convection and vacuum) on some physical characteristics such as hectoliter weight, thousand kernel weight, dimensions (thickness, length, width, equivalent diameter and sphericity) of corn during drying. Before drying, corn samples were pre-treated without ultrasound (conventional-soaking) and with ultrasound (40 kHz 200 W, 50 and 100% amplitude) during 1 hour soaking. Pre-treated samples were dried at 80, 90 and 100 ᵒC in the laboratory type vacuum dryer and hot-air convection dryer. Moisture content, dimensions (length, width, thickness, equivalent diameter and sphericity), thousand kernel weight and hectoliter weight of pre-treated corn samples at each temperature were analyzed for every 60 min during 240 minutes of drying processes. When the research results were analyzed, the length, width and equivalent diameter values of the corn samples dried in vacuum and hot air convection dryer were found significantly different between 0-60 minutes (P≤0.05), but insignificant (P&amp;gt;0.05) in the following periods. While the decrease in thickness of corn samples dried in vacuum dryer was significant (P≤0.05), the decrease in thickness of corn samples dried in hot air convection dryer was found insignificant (P&amp;gt;0.05). The increase in sphericity of the corn samples dried in vacuum dryer during drying was significant (P≤0.05), but the increase in the hot air convection dryer was insignificant (P&amp;gt;0.05). The effect of ultrasonic pre-treatment and dryer temperature on the size of the corn samples was found to be insignificant (P&amp;gt;0.05), while the effect of vacuum drying on the size of the corn samples was significant (P≤0.05). The effect of ultrasound pre-treatment, drying temperature and drying time on moisture content, thousand kernel weight and hectoliter weight of corn grains were found to be significant (P≤0.05). As a result, the vacuum dryer, allowed the corn to dry in a short time without much change in the structure of the corn.

Biogas production by an anaerobic co-digestion process from olive mill waste: effect of ultrasonic pre-treatment

Biogas production by an anaerobic co-digestion process from olive mill waste: effect of ultrasonic pre-treatment