Kneading Time Research Articles

A Vision System for Surface Homogeneity Analysis of Dough Based on the Grey Level Co‐occurrence Matrix (GLCM) for Optimum Kneading Time Prediction

AbstractThis paper presents an investigation of a methodology for predicting the optimum time to decide dough readiness by using two‐dimensional imaging and statistical texture analysis. Based on the master baker experience and the torque curve generated by the dough mixer, the system will be correlated to stop the kneading process with the minimum error on the optimum time or point of maximum dough development (peak consistency). This development takes advantage of the gray level co‐occurrence matrix (GLCM) texture analysis for the development of an algorithm to emulate the visual inspection performed by the master bakers, where the homogeneity feature of dough is analyzed during the kneading time. An automatic graphical user interface software for offline and inline analysis was developed for the homogeneity analysis. The programmed algorithm was implemented in many experiments (online and offline) for testing, producing an average error of 33.9 s with respect to average optimal mixing time.Practical ApplicationsThe development of a dough analyzing method, on the basis of an optical surface evaluation, represents an entirely new way to look at the dough properties. The possibility of applying an online dough judgment method without any losses will be given. Simple upgrading of existing production lines can help to prevent erroneous processing and to increase the quality of the end product. Instantaneous state of the art for determining the optimum dough development or dough readiness is the visual and tactile evaluation of the technical staff and laboratory investigations. The expansion of the indirect method by a digital interface‐based analytic approach provides a significant improvement in industrial bakery production and a potential direct method for dough analysis.

Developing a xylanase XYNZG from Plectosphaerella cucumerina for baking by heterologously expressed in Kluyveromyces lactis.

BackgroundXylanase can replace chemical additives to improve the volume and sensory properties of bread in the baking. Suitable baking xylanase with improved yield will promote the application of xylanase in baking industry. The xylanase XYNZG from the Plectosphaerella cucumerina has been previously characterized by heterologous expression in Pichia pastoris. However, P. pastoris is not a suitable host for xylanase to be used in the baking process since P. pastoris does not have GRAS (Generally Regarded As Safe) status and requires large methanol supplement during the fermentation in most conditions, which is not allowed to be used in the food industry. Kluyveromyces lactis, as another yeast expression host, has a GRAS status, which has been successfully used in food and feed applications. No previous work has been reported concerning the heterologous expression of xylanase gene xynZG in K. lactis with an aim for application in baking.ResultsThe xylanase gene xynZG from the P. cucumerina was heterologously expressed in K. lactis. The recombinant protein XYNZG in K. lactis presented an approximately 19 kDa band on SDS-PAGE and zymograms analysis. Transformant with the highest halo on the plate containing the RBB-xylan (Remazol Brilliant Blue-xylan) was selected for the flask fermentation in different media. The results indicated that the highest activity of 115 U/ml at 72 h was obtained with the YLPU medium. The mass spectrometry analysis suggested that the hydrolytic products of xylan by XYNZG were mainly xylobiose and xylotriose. The results of baking trials indicated that the addition of XYNZG could reduce the kneading time of dough, increase the volume of bread, improve the texture, and have more positive effects on the sensory properties of bread.ConclusionsXylanase XYNZG is successfully expressed in K. lactis, which exhibits the highest activity among the published reports of the xylanase expression in K. lactis. The recombinant XYNZG can be used to improve the volume and sensory properties of bread. Therefore, the expression yield of recombinant XYNZG can be further improved through engineered strain containing high copy numbers of the XYNZG, and optimized fermentation condition, making bread-baking application possible.

CIIR 예비가교물의 니더가공이 BR/PCIIR 복합체의 물리적 특성에 미치는 영향

BR/PCIIR 복합체에 대한 분산상의 영향을 분석하기 위하여 예비가교된 CIIR을 BR과 함께 니더가공하여 고무복합체를 제조하였다. 분산상으로 사용된 CIIR 예비가교물을 니더에서 한번 더 가공함으로써 BR/PCIIR 복합체에서 분산상의 입자가 적어지고 균일하게 분산되었다. BR/PCIIR40의 경우 예비가교물의 니더 가공 시간이 복합체의 반발탄성 및 경도에 아무런 영향을 미치지 않았다. 예비가교된 CIIR 입자를 니더기로 가공한 후 BR에 혼합하여 복합체를 제조한 경우, 니더가공하지 않은 복합체의 인장강도에 비하여 10% 이상 현저히 향상되었다. 분산상으로 사용되는 CIIR 예비가교물을 니더로 가공함으로서 복합체의 표면마찰 특성은 그대로 유지하면서도 복합체의 내마모성 및 기계적 성질은 현저히 향상되었다. Rubber composites were prepared by kneading the precured CIIR with BR in order to analyze the effects of the dispersed phase on the BR/PCIIR composites. The particle size of domain in BR/CIIR composites was decreased and homogeneously dispersed by kneading process the precured CIIR used as dispersed phase in kneader once again. In case of BR/PCIIR40, the kneading time of precured CIIR with BR did not have any effect on the rebound resilience and the hardness of the composite. The tensile strength of the composite prepared by kneading precured CIIR particles and then mixing them with BR increased significantly more than 10% when compared to that of the composite which was not kneaded. The composite maintained the surface friction property while increasing anti-abrasion and mechanical properties significantly by kneading the precured CIIR used as dispersed phase.

Assessment of Nanocatalyst Dispersibility in a Polymer by Employing Relative Standard Deviation

A relative standard deviation (RSD) method has been developed to evaluate the nanocatalyst dispersibility in an energetic polymer. The dispersibility of nanocatalyst and thermal characteristics of the polymer exhibits high dependence on the RSD of the concentration distributions of nanocatalyst. The improvement of the dispersibility of nanocatalyst, which is dependent on kneading time, can be presented by a decrease in the RSD of the concentration distributions. Moreover, the decomposition temperature and the combustion heat of the polymer is reduced gradually and enhanced distinctly, respectively, with the decrease of the RSD of the nanocatalyst distributions. However, over-kneading may lead to a reunion of nanocatalyst and a decline of thermal characteristics of the energetic polymer, and presented with an increasing of the RSD of the concentrations of nanocatalyst. The optimal kneading time is 3 h and an acceptable value of the RSD is approximately 1% of the concentration distributions of nanocatalyst for the energetic polymer with nanometer copper oxide catalyst.

An investigation on the correlation between drug dissolution properties and the growth behaviour of granules in high shear mixer

The aim of this study was to investigate the correlation between the growth behaviour and in-vitro dissolution rate of water-insoluble drugs prepared with high-shear wet granulation. Granules containing nimodipine, microcrystalline cellulose, low-substituted hydroxypropylcellulose and aqueous solution of hydroxypropylcellulose were prepared and the effects of independent process variables, including impeller speed and liquid-to-solid ratio were taken into consideration. The mean granule size, granule-size distribution (GSD), porosity and surface properties were monitored at different kneading times to identify the granule-growth mechanisms simultaneously. A computer-based method was applied to simulate the dissolution behaviour of polydisperse granules based on the GSD data. The in-vitro dissolution rate of drug was high for the early stages of granulation and sharply decreased when coalescence and consolidation of granules started, approaching a flat and low level when granules were sufficiently consolidated. The simulated dissolution results were in agreement with experimental observations and were significantly affected by the GSD, porosity and surface properties of granules during the granulation process. Moreover the GSD was directly related to the granule-growth behaviour and mechanisms. In general, it was concluded that the dissolution properties of nimodipine basically correlated with the growth behaviour of granules in a high-shear mixer. The simulation method based on GSD can be used as a convenient and rapid way to predict the dissolution properties for formulation development and granulation optimization.

Effect of the Dispersibility of Nano-CuO Catalyst on Heat Releasing of AP/HTPB Propellant

Kneading time is adjusted to change the dispersibility of nano-CuO in AP/HTPB (Ammonia Perchlorate/Hydroxyl-Terminated Polybutadiene) composite propellants. Nano-CuO/AP is prepared to serve as the other dispersing method of nano-CuO, named predispersing procedure. Several kinds of heat releasing, thermal decomposition by DSC, combustion heat in oxygen environment, and explosion heat in nitrogen environment, are characterized to learn the effect of dispersibility of nano-CuO catalyst on heat releasing of propellants. With pre-dispersing procedures, thermal decomposition temperature of nano-CuO/AP and its propellant are about C and C lower than that of AP simple mixed with nano-CuO and its propellant, respectively. Comparing propellant with simple mixed nano-CuO kneading 3 hours, combustion heat and explosion heat of propellant with nano-CuO/AP increase about 1.4% and 1.7%, respectively. However, because of the breaking of nano-CuO/AP structure during kneading procedure, combustion heat and explosion heat of all the samples are decreased with the increase of kneading time after 3 hours.

Kneading Technique for Preparation of Binary Solid Dispersion of Meloxicam with Poloxamer 188

The aim of the present study was to enhance the dissolution rate of meloxicam (MLX), a practically water-insoluble drug by preparation of solid dispersion using a hydrophilic polymer, poloxamer 188 (PXM). The kneading technique was used to prepare solid dispersions. A 3(2) full factorial design approach was used for optimization wherein the drug, polymer ratio (X1), and the kneading time (X2) were selected as independent variables and the dissolution efficiency at 60 min (%DE60) and yield percent were selected as the dependent variable. Multiple linear regression analysis revealed that for obtaining higher dissolution of MLX from PXM solid dispersions, a high level of X1 and a high level of X2 were suitable. The use of a factorial design approach helped in optimization of the preparation and formulation of solid dispersion. The optimized formula was characterized by solubility studies, angle of repose, and contact angle; Fourier transform infrared spectroscopy, differential scanning calorimetry, x-ray diffraction studies, and scanning electron microscopy demonstrated that enhanced dissolution of MLX from solid dispersion might be due to a decrease in the crystallinity of MLX and PXM. Analysis of dissolution data of optimized formula indicated the best fitting with Korsemeyer-Peppas model and the drug release kinetics as Fickian diffusion. In conclusion, dissolution enhancement of MLX was obtained by preparing its solid dispersion with PXM using kneading technique.

Study on Kneading and Molding of PP/TiO2 Nanocomposite

Abstract This paper investigates the kneading and molding of PP (polypropylene) with nano-TiO2 (Titanium dioxide) powder having sizes in the range of 50 nm. It was found that quality feedstock with uniform nanopowder dispersion was achieved only when the kneading was performed for optimum time under optimum torque using a custom-made triple-screw kneader with a high shear stress. The torque and kneading time needed for PP composite with 40 wt.% nano-TiO2 is double that required for the one with 10 wt.%. Rheological and impact properties of composites with 10 wt.% and 40 wt.% filler loading were also analyzed. In addition, a very important result revealed that a simple micro-grating can be successfully used as a mold insert to replicate micro-features made with PP/nano-TiO2 feedstock using injection molding conducted under a high forming pressure and evacuation of the mold.

Effect of Malaxation Conditions on Phenol and Volatile Profiles in Olive Paste and the Corresponding Virgin Olive Oils (Olea europaea L. Cv. Cornicabra)

Malaxation of olive paste must be considered to be much more than a simple physical separation, because a complex bioprocess takes place that is very relevant to the quality and composition of the final product. A combined study of the effect of kneading temperature and time on the minor composition of olive paste and its corresponding virgin olive oil, processed in an experimental oil mill (Pieralisi, Fattoria) with a working capacity of 200 kg/h, is reported. A large drop in the oleuropein content in the olive paste with respect to its initial content in the olive fruit (between 92 and 96%) was observed, which suggested its almost total degradation during the crushing operation. The major phenolic compound found in the olive paste during kneading was the dialdehydic form of elenolic acid linked to hydroxytyrosol (3,4-DHPEA-EDA, always higher than 60% of the total phenols). This greatly decreased during malaxation (from 5505 to 2317 mg/kg, on average). The content of phenolic compounds in virgin olive oil was much more affected by the malaxation temperature than the kneading time. For instance, the 3,4-DHPEA-EDA content increased by 220-630% in the two batches when the temperature was increased from 20 to 40 degrees C. A reduction in the C6 aldehydes was found in virgin olive oil as the malaxation temperature increased, especially in E-2-hexenal (30% reduction). In contrast, C6 aldehydes in the oils from the oil mill plant significantly increased as the malaxation time increased from 30 to 90 min, chiefly E-2-hexenal (about a 70% increase).

Influence of malaxation conditions on virgin olive oil yield, overall quality and composition

The production of a high quality product requires good manufacturing practices and effective quality assurance throughout the whole process. The aim of this study was to improve the knowledge of the technological variables involved in the malaxation operation, which affect the yield and in particular the overall quality of the virgin olive oil. A continuous experimental virgin olive oil mill plant (Pieralisi, Fattoria) was employed, working at 200 kg/h olive paste, and the paste was kneaded at different temperatures (20–40 °C) and times (30–90 min). The industrial oil yield improved when either the kneading temperature or the kneading time was increased, but the temperature affected more the oil yield than the time (yield increased by about 28%, from 20 to 40 °C). The total phenol and o-diphenol contents in virgin olive oils, which affect both the sensory bitterness and the oxidative stability of the oils, greatly improved with the increase in the malaxation temperature. On the contrary, a longer kneading time only led to a slight decrease in the total phenols. This fact is very important since excessive levels of phenols, typical of Cornicabra virgin olive oils, may adversely affect consumer preference for this highly valued product.

Blending LLDPE and Ground Rubber Tires

In this article, a set of blends was prepared from ground rubber tires (GRT) and linear low-density polyethylene (LLDPE). The effects of kneading time and functional polymers on the mechanical properties of the blends were investigated. It was found that the blend which contained styrene-butadiene-styrene (SBS) copolymer as functional polymer, with a kneading time of 20 minutes, behaved best with regard to mechanical properties, and that the utilization of GRT could reach as high as 61%. Atomic force microscopy (AFM) and differential scanning calorimetry (DSC) results showed that good adhesion between the particles and the surrounding LLDPE matrix was achieved in the blend.

Investigation of High Shear Wet Granulation Processes Using Different Parameters and Formulations

This study compared the granulation processes for different formulations using a laboratory-scale high shear mixer. The effects of critical process parameters (impeller speed, chopper speed and kneading time) on granule characteristics were evaluated. The characteristics of the granules studied included the size distribution, friability and morphological properties. The flow profiles of the wet mass and material deposition during the process were also studied. The results obtained showed that the effect of the impeller speed was determined by the starting material system. On the other hand, chopper speeds from 1200 to 3600 rpm and kneading times from 120 to 240 s had a consistent influence on all formulations. Moreover, it was found that the toroidal flow pattern of the wet mass could be maintained for a longer period and granules with a good spherical shape were obtained by removing the chopper during the last 120 s of the granulation process. In addition, the use of the pregelatinized starch in the formulation also led to a reduction in the wall adhesion of the material. It was concluded that the effectiveness of high shear wet granulation could be improved by choosing a proper combination of starting material and process parameters and by monitoring the mass motion during the process.

Importance of evaluating the consolidation of granules manufactured by high shear mixer

The effects of the process parameters of high shear wet granulation on the granule properties and dissolution properties of mefenamic acid from tablets have been studied, and the importance of evaluating the consolidation of granules has been considered. The process parameters selected for investigation were the amount of water added, the impeller rotation speed and the kneading time. Increases in the amount of water and the kneading time led to increases in the particle diameter of the granules and to decreases in the mean pore diameter. The mean pore diameter decreased with increases in the impeller rotation speed, while the particle diameters were independent of the impeller rotation speed. The process parameters affected the surface morphology and the internal morphology of the granules. The mean particle diameter and the mean pore diameter of the granules basically correlated with the dissolution properties of the tablets. The contribution of the mean pore diameter to this correlation was higher than that of mean particle diameter. Therefore, it was concluded that evaluation of the granule consolidated state, such as the mean pore diameter, was important in order to assure the dissolution properties of drug products.

Development and optimization of solid dispersion containing pellets of itraconazole prepared by high shear pelletization

This study investigated the solid dispersion containing pellets of itraconazole for enhanced drug dissolution rate. The influence of process parameters used during high shear pelletization on the pellet properties including pellet size and dissolution rate was also studied. Solid dispersions of itraconazole were prepared with Eudragit ® E100, a hydrophilic polymer, by a simple fusion method followed by powdered and characterized by differential scanning calorimetry and X-ray powder diffraction. Solid dispersions containing pellets were consequently prepared using a lab-scale high shear mixer. In order to improve the product quality, a central composite design was applied to optimize the critical process variables, such as impeller speed and kneading time, and the results were modeled statistically. Itraconazole was presented as an amorphous state in the solid dispersion prepared at a drug to polymer ratio of 1:2. Both studied parameters had great effect on the responses. Powdered solid dispersion and pellets prepared using the optimal parameter settings showed approximately 30- and 70-fold increases in dissolution rate over the pure drug, respectively. Solid dispersion prepared by simple fusion method could be an option for itraconazole solubility enhancement. Pelletization process in high shear mixer can be optimized effectively by central composite design.

Parameters controlling the glycaemic response to breads

Bread is one of the most widely consumed staple foods worldwide. White-wheat bread, largely consumed in France, is made from highly refined flour, which leads to a low nutrient density. Due to a highly porous structure and gelatinised starch, it is easily broken down during digestion, leading to a rapid increase of glucose released into the bloodstream. Low glycaemic responses are considered favourable to health, especially against a background of diabetes. Literature reports show that selection of raw material is an essential factor in decreasing the glycaemic index (GI) of white bread. There are two means of decreasing the rate of starch degradation: either (i) slowing gastric emptying rate and/or glucose diffusion-absorption through the intestinal mucosa, which can be achieved by incorporating soluble fibre or organic acid in bread, or (ii) limiting starch accessibility to alpha-amylase by using high-amylose cereal varieties and/or incorporating intact cereal grains. Studies on cereal products show that preservation of the food structure during digestion seems to be a more important GI-reducing factor than the degree of starch crystallinity or the presence of soluble fibre. Thus, we should look to produce bread with a more compact food structure or higher density, which is the case in leavened wholewheat bread or bread with intact cereal grains. The baking process should also be improved to achieve this goal, by using, for example, a reduced kneading time or less yeast than usual.

De‐Agglomeration Kinetics of Feedstocks with Granule Tetragonal Zirconia Polycrystalline Powder

This study establishes the relationship between homogeneity of tetragonal zirconia polycrystalline (TZP) feedstocks and the kneading time in order to understand the kneading energy adsorption during the de‐agglomeration period of pre‐existing ceramic granules. Two spray‐dried Y‐TZP powders with different compress strengths were investigated using torque rheometer and transmission optical microscopy. Several properties, kneading torque (T), Casson viscosity (μ), Reynolds number (Re), and dispersive index (Ds) of the feedstocks were introduced, and monitored as a function of kneading time. Optimal processing windows were identified from the dependence of dispersive index with a power number (Np). The best shear‐kneading procedure was proposed in consideration of best feedstock homogeneity and shortest kneading time. One homogenous feedstock and two comparable cases were prepared for subsequent injection molding, debinding, sintering, and mechanical testing. The fracture strength of sintering parts by a partially homogeneous feedstock can be improved from 520 to 680 MPa by a homogeneous feedstock.

Impact of Industrial Dough Processing on Structure: A Rheology, Nuclear Magnetic Resonance, and Electron Microscopy Study

ABSTRACTDough processing is an important factor determining the quality of bread. The most important mechanical steps in industrial dough processing are kneading, extrusion, and molding. In all of these processing steps, considerable changes in the structure and properties of the dough can occur. On a laboratory‐scale level, these (structural) effects are well characterized but, so far, no systematic study has been performed at the level of a large‐scale industrial dough processing line. The molecular and microstructural changes that can take place during industrial dough processing were studied with the help of nuclear magnetic resonance (NMR), fundamental rheology, and scanning electron microscopy (SEM). After the kneading step, the dough shows a well‐developed gluten network with a homogeneous dispersion of starch particles (at optimum kneading time). After the extrusion step (a sheeting procedure), the structure of the dough becomes coarser and the dough gluten network is oriented and partially disrupted. This is accompanied with an increase in both rheological stress and water mobility. After molding, the network structure is restored and both the rheological stress and the mobility of water decrease. These findings provide a novel microstructurally‐lead approach to make recommendations for optimization of industrial dough processing lines.

Development of a novel compression tester and rheo-mechanical properties of wet-mass powder. I--Effect of kneading time on the rheo-mechanical properties.

In our previous paper [Watano S., et al., Chem. Phram. Bull., 49(1), 64-68, (2001)], a compaction tester was developed to quantitatively evaluate the water dispersion condition of wet kneaded masses prepared by a paddle type kneader. It was also demonstrated that the physical properties of pellets prepared by extrusion granulation after the kneading could be well predicted by the vertical pressure transmission obtained through the compaction tester. However, in this compression tester, the vertical pressure transmission was just obtained and rheological and mechanical properties (so called rheo-mechanical properties) of wet mass-powder that should be the most important to determine the deformation process were not well studied. In this study, a novel compression tester, which can measure both vertical and radial pressure transmissions, has been developed. Based on the compression test, mechanical property (Young's modulus) and rheological property (effective internal friction) of wet mass powder prepared by different kneading times were quantitatively investigated. Granules (pellets) were then obtained through the extrusion granulation and fluidized bed drying, and the physical properties (strength and disintegration time) of the obtained pellet were evaluated. The relationship between the granule (pellet) physical properties and the mechanical and rheological (rheo-mechanical) properties was analyzed.

Development of a novel compression tester and rheo-mechanical properties of wet-mass powder. II--Effect of moisture content on the rheo-mechanical properties.

In our previous paper [Watano S., et al., Chem. Pharm. Bull., 51(7), 747-750 (2003)], a novel compression tester, which enables the vertical and radial pressure transmission measurement, has been developed and quantitative analysis of rheo-mechanical properties of wet-mass powder prepared by different kneading times was conducted. In this study, the compression test was conducted by using the kneaded wet-mass powders prepared by different moisture contents. Pressure transmission characteristics and rheo-mechanical properties have been investigated to characterize the wet-mass powders. The relationship between these parameters and granule physical properties was also investigated.

Studies on the Granulation Process of Granules for Tableting with a High Speed Mixer. III. Analysis of the Compression Process.

Several kinds of theophylline granules were prepared in a high speed mixer by varying the kneading time, and their compression processes were analyzed by Heckel and by Cooper and Eaton equations. The compressibility of those granules was also examined comparatively by analyzing the compression energy applied to the powder layer to determine the relation between the compression behavior, compression energy, tablet hardness and internal structure of the tablet.The granules having the largest pore volumes were found to have high tablet hardness and tended to show larger ratios of compression loss energy to compression energy. It was suggested that in the granules having the largest pore volumes, the pores were easily filled by particle movement, rearrangement, plastic deformation and brittle fracture upon compression and the energy applied to the powder layer upon tableting was consumed efficiently.