Behic Mert

Reducing saturated fat with oleogel/shortening blends in a baked product.

Short dough cookie structure, characterized by its aerated and tender texture, depends on the presence of solid fat during kneading. The objective of this study was to investigate the potential application of Candelilla wax (CDW) containing oleogels for partial replacement of the shortening in cookies. Oleogels were prepared with different amounts of CDW and blended with a commercial bakery shortening. After crystallizing the oleogel/shortening blends by using a pilot scale crystallization unit, the blends were evaluated in a cookie formulations. When the shortening was completely replaced with oleogel softer products were obtained compared to liquid oil, but they were harder than the shortening containing products. On the other hand, partial replacement of shortening with oleogels provided much more acceptable dough and cookie characteristics. Results suggest that gradual replacement of shortening with oleogels may be a suitable approach for reduction of saturated fat in short dough products.

A novel method to measure the glass and melting transitions of pharmaceutical powders

A method to measure thermo-mechanical properties of pharmaceutical and polymeric powders was developed. The measurements are conducted by characterizing the materials response to applied acoustic waves. Measurements were performed using griseofulvin, felodipine and indomethacin as model drugs and polyethylene oxide (MW=200,000, 900,000, 2,000,000Da) as model polymers. The method employed measures the mechanical impedance enabled the calculation of the powder rheological and thermo-mechanical properties. Measurements attained with this new technique are compared with measurements made using differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). The new method detects the melting and glass transitions events while providing complementary information to that provided by DSC and DMA.

Optimization of Ethanol Production From Microfluidized Wheat Straw by Response Surface Methodology

In this study, wheat straw was pretreated with a microfluidizer to improve its enzymatic hydrolysis and ethanol yields. The pretreatment was performed at various pressures (500, 1000, and 1500 bar) and solid loadings (1, 2, and 3%). The microfluidized biomass was then subjected to hydrolysis and simultaneous saccharification and co-fermentation (SSCF) experiments at different enzyme loadings (5, 10, and 15 FPU/g dry wheat straw) using a mutant yeast. The results indicated that the microfluidization method alters the structure of biomass and leads to a reduction in lignin content. The samples pretreated at 1% solid loading contained the minimum lignin concentration and provided the maximum sugar and ethanol yields. These results signified that the microfluidization method is more effective on biomass at low solid loadings. The process conditions were optimized for higher ethanol and sugar yields using response surface methodology (RSM). The optimum pressure and solid and enzyme loadings were found as 1500 bar, 1%, and 15 FPU/g dry wheat straw, respectively. The yields obtained at this condition were 82%, 94%, and 65% for glucose, xylose, and ethanol, respectively. High sugar yields implied that microfluidization is an effective pretreatment method for cellulosic ethanol production. On the other hand, low ethanol yield may indicate that the microorganism was sensitive to inhibitory compounds present in the fermentation medium.

Production of Microfluidized Wheat Bran Fibers and Evaluation as an Ingredient in Reduced Flour Bakery Product

In this study, the potential use of microfluidization as a milling process for wheat bran was evaluated. More specifically, the influences of regular wheat bran and microfluidized wheat bran on quality (hardness, cutting force, specific volume, and color) and storage characteristics of model bakery product cake were compared. Microfluidization process led to formation of the finely separated fibrous structure with great surface area that allowed higher water holding capacity and methanol soluble-free phenolic content. Rheological measurements showed that the increased surface area of fibers also allowed bran fiber to intertwine and form strong fibrous matrix resulting in higher consistency index, yield stress, and viscoelastic moduli values in batter samples. Various flour formulations have been also tested in the presence of microfluidized wheat bran, and in reduced flour-containing samples, a fibrous network provided gluten-like strength to the batter and cake samples. Microfluidized wheat bran also affected color of cake samples. High water holding ability of microfluidized wheat bran had also impact on moisture loss and staling rate of the cake samples. These results show that microfluidized wheat bran could be an alternative functional ingredient in bakery products.

Effect of high hydrostatic pressure and high dynamic pressure on stability and rheological properties of model oil-in-water emulsions

Both static and dynamic high pressure applications provide interesting modifications in food structures which lead to new product formulations. In this study, the effects of two different treatments, high hydrostatic pressure (HHP) and high dynamic pressure (HDP), on oil-in-water emulsions were identified and compared. Microfluidization was selected from among the HDP homogenization techniques. The performance of each process was analyzed in terms of rheological modifications and emulsion stability improvements compared with the coarse emulsions. The stability of the emulsions was determined comparatively by using an analytical photo-centrifuge device employing novel analysis technology. Whey protein isolate (WPI) in combination with a food polysaccharide (xanthan gum, guar gum or locust bean gum) were used as emulsifying and stabilizing ingredients. The effective disruption of oil droplets and the degradation of polysaccharides by the shear forces under high pressure in HDP microfluidization yielded finer emulsions with lower viscosities, leading to distinctive improvements in emulsion stability. On the other hand, improvements in stability obtained with HHP treatment were due to the thickening of the emulsions mainly induced by protein unfolding. The corresponding increases in viscosity were intensified in emulsion formulations containing higher oil content. Apart from these, HHP treatment was found to be relatively more contributive to the enhancements in viscoelastic properties.

Production of hazelnut skin fibres and utilisation in a model bakery product

Microfluidisation was used as a potential method for the production of fibrous structure from hazelnut skin (HS), and which was evaluated as an ingredient in cake as model bakery product. More specifically, effects of different amounts of microfluidised HS on rheological behaviour of cake batter and quality parameters (texture and colour) and storage characteristics of cake products were evaluated. Furthermore, performance of microfluidised HS was compared with conventionally milled HS and cacao powder for comparison purpose. The entangled structures of microfluidised HS resulted in much higher consistency index, yield stress and viscoelastic moduli values in batter samples than conventionally milled hazelnut skin. Highly shredded fibrous structure of microfluidised HS provided gluten-like strength and elasticity to cake samples resulting in higher springiness and firmness values. Darker crumb colour of the cake samples was caused by the homogenous distribution of fibrous microfluidised HS. Detailed staling analysis through X-ray and Fourier transform infrared measurements showed that microfluidised HS containing cake samples had lower retrogradation and staling tendency due to their lower starch content, and higher water holding ability. Findings of this study showed that microfluidised HS could be potentially utilised as an ingredient in bakery products.

Physical characterization of low-calorie chocolate formulations

Development of a high-quality low-calorie chocolate needs the use of the most appropriate ingredients that could substitute sugar without negatively affecting several product properties. In this study, sucrose-reduced chocolates sweetened with sucralose and stevia by using bulking agents were investigated in relation to their rheological, textural and sensory attributes. Dark, milk and white chocolates with different amounts of sweeteners were formulated. The Casson model best fitted to the rheological data. In dark chocolates, partial substitution of sucrose with stevia (DCSSt) gave similar plastic viscosity and yield stress values with control samples (DCS). Hardness measurements also supported these results. DCSSt sample was again found to be very similar to control in tested sensory attributes when assessed by a consumer panel. The data indicated that it was possible to manufacture chocolate by partial replacement of sucrose with stevia without adversely affecting its important rheological, textural properties and sensory acceptance.

The Use of Vibration Principles to Characterize the Mechanical Properties of Biomaterials

Mechanical properties are a primary quality factor in many materials ranging from liquids to solids including foods, cosmetics, certain pharmaceuticals, paints, inks, polymer solutions, to name a few. The mechanical properties of these products are important because they could be related to either a quality attribute or a functional requirement. Thus, there is always a need for the development of testing methods capable to meet various material characterization requirements from both the industry and basic research. There is a wide range of mechanical tests in the market with a wide price range. However, there is an increasing interest in finding new methods for mechanical characterization of materials specifically capable to be adapted to in-line instruments. Acoustic/vibration methods have gained considerable attention and several instruments designed and built in government labs (e.g. Pacific Northwest National Laboratory and Argon National Laboratory) have been made commercially available. To measure mechanical properties of material a number of conventional techniques are available, which in some cases may alter or change the sample during testing (destructive testing). In other tests the strains/deformations applied are so small that the test can be considered non-destructive. Both types of test are based on the application of a controlled strain and the measurement of the resulting stress, or viceversa. Different types of deformations, e.g. compression, shear, torsion are used to test these materials. Depending on the type of material, different conventional techniques utilized to measure its mechanical properties can be grouped as viscosity measurement tests (liquid properties), viscoelasticity measurement tests (semiliquid/semisolid properties), and elastic measurement tests (solid properties). Acoustics based techniques can be used for all types of material and the following sections discuss in detail how these techniques have been adapted and used to measure materials whose properties range from liquids to solids. Some of the applications discussed in this chapter are based on the basic impedance tube technique. Applications of this technique for

Different sized wheat bran fibers as fat mimetic in biscuits: its effects on dough rheology and biscuit quality

The aim of this study is to investigate the effects of various particle sized and different amount of plant fibers as fat mimetic for biscuit formulations instead of biscuit fat. The fibers with different particle sizes were obtained from wheat bran and used instead of fat in biscuit formulations. The texture, rheology and quality analyses of low-fat biscuit (30, 20 and 10% fat) were performed and compared with those of the full-fat control sample (40% fat). Results showed that wheat bran fiber with bigger particle size (Long Fiber, LF) were more favorable in terms of textural properties of the dough and the quality parameters of biscuits while the fibers with smaller particle size (Medium Fiber, MF and Small Fiber, SF) improved viscoelastic properties of dough similar to the control. Although the use of these fibers in the production of low-fat biscuits were suitable in terms of workability of dough increasing fiber content and/or reducing fiber size resulted in harder biscuits with lower spread ratio. This study showed that the texture of biscuits was greatly dependent on the texture of the dough.

Development of pH sensitive alginate/gum tragacanth based hydrogels for oral insulin delivery

Insulin entrapped alginate-gum tragacanth (ALG-GT) hydrogels at different ALG replacement ratios (100, 75, 50, 25) were prepared through an ionotropic gelation method, followed by chitosan (CH) polyelectrolyte complexation. A mild gelation process without the use of harsh chemicals was proposed to improve insulin efficiency. Retention of almost the full amount of entrapped insulin in a simulated gastric environment and sustained insulin release in simulated intestinal buffer indicated the pH sensitivity of the gels. Insulin release from hydrogels with different formulations showed significant differences ( p < 0.05). Time domain (TD) NMR relaxometry experiments also showed the differences for different formulations, and the presence of CH revealed that ALG-GT gel formulation could be used as an oral insulin carrier at optimum concentrations. The hydrogels formulated from biodegradable, biocompatible, and nontoxic natural polymers were seen as promising devices for potential oral insulin delivery.