Ioanna Mandala

Xanthan effect on swelling, solubility and viscosity of wheat starch dispersions

Xanthan effect on swelling power (SP), solubility index (SOL) and granules status of wheat starch dispersions (2% w/w) was investigated. Control samples and samples with xanthan (0.09% w/w at the final solution) were prepared and heated at temperatures from 60 to 90 8C for 5 or 30 min. Additionally, the viscosity of starch‐ xanthan mixtures was calculated at different shear rates. Regarding these mixtures two preparation techniques were used: separate preparation of starch and xanthan solutions and subsequent mixing (a), or mixture of the powders prior to addition of water (b). Samples were heated at two different temperatures 75, 90 8C and times 5, 30 min. According to SP values and granules dimensions at 75 8C, xanthan addition enhanced swelling. It also enhanced starch polymers leakage at temperatures , 80 8C. At higher temperatures lower SOL values were found than those of control samples. Furthermore, in the presence of xanthan the proportion of large granules was greater than this found in aqueous solution. However, xanthan induced granules folding, which was noticed even at relatively low temperatures (75 8C). With respect to viscosity, all samples showed pseudoplastic behaviour. Experimental values were fitted well by the Ostwald ‐ de Waele model ðs ¼ k· _ g n Þ: Consistency values ðkÞ and flow index ðnÞ were mainly influenced by the preparation

Influence of preparation and storage conditions on texture of xanthan-starch mixtures

Starch and xanthan improve the texture of several foods. Furthermore in some cases food containing these ingredients are stored before being further used. Soluble potato starch dispersions with xanthan were prepared separately at 75 and 90 °C, mixed and stored at 5 or 25 °C. TPA experiments and microscopic observations took place. Samples prepared at 75 °C were composites of starch granules (filled or empty) embedded in a continuous phase of xanthan and amylose, while those prepared at 90 °C contained fragments, large granules or agglomerates in the continuous phase of amylose, amylopectin and xanthan. The 90 °C samples were stiffer, fragile and had reduced springiness and cohesiveness. Storage at low temperature enhanced the final rigidity of samples as did the inclusion of xanthan. Xanthan formed also microphase-separated domains and was concentrated around the granules.

Bacterial Cellulose Production from Industrial Waste and by-Product Streams.

The utilization of fermentation media derived from waste and by-product streams from biodiesel and confectionery industries could lead to highly efficient production of bacterial cellulose. Batch fermentations with the bacterial strain Komagataeibacter sucrofermentans DSM (Deutsche Sammlung von Mikroorganismen) 15973 were initially carried out in synthetic media using commercial sugars and crude glycerol. The highest bacterial cellulose concentration was achieved when crude glycerol (3.2 g/L) and commercial sucrose (4.9 g/L) were used. The combination of crude glycerol and sunflower meal hydrolysates as the sole fermentation media resulted in bacterial cellulose production of 13.3 g/L. Similar results (13 g/L) were obtained when flour-rich hydrolysates produced from confectionery industry waste streams were used. The properties of bacterial celluloses developed when different fermentation media were used showed water holding capacities of 102–138 g·water/g·dry bacterial cellulose, viscosities of 4.7–9.3 dL/g, degree of polymerization of 1889.1–2672.8, stress at break of 72.3–139.5 MPa and Young’s modulus of 0.97–1.64 GPa. This study demonstrated that by-product streams from the biodiesel industry and waste streams from confectionery industries could be used as the sole sources of nutrients for the production of bacterial cellulose with similar properties as those produced with commercial sources of nutrients.

Effect of Carob Flour Addition on the Rheological Properties of Gluten-Free Breads

In this study, the rheological properties of gluten-free doughs from rice flour containing different amounts of carob flour were investigated. Water added changed in response to the carob amount. Dynamic oscillatory and creep tests were performed in order to gain knowledge on the rheological behaviour of doughs, which is essential for the control of the bread-making procedure and the production of high-quality bread. Simple power law mathematical models were developed in order to evaluate the effect of carob and water added in dough rheological behaviour. Creep data evaluation demonstrates that an increase in water content decreased the resistance of dough to deformation and, therefore, dough strength, whereas carob flour increased the elastic character and structure strength of the dough. This was also found in dynamic oscillatory tests. Increased amounts of carob flour led to an increase in bread dough elastic character since fibre addition elastifies and strengthens the dough structure. Moreover, doughs exhibited a solid-like viscoelastic character, with the storage modulus (G′) predominant over the loss modulus (G″). Dough rheological properties have an important effect on baking characteristics. Rheological experiments and applied mathematical models can provide us with good knowledge of rheological behaviour and dough viscoelasticity prediction. Therefore, dough samples containing carob-to-water ratios of 10:110 and 15:130 can be considered to possess a balance between the viscous and elastic properties compared to the other samples.

Influence of jet milling and particle size on the composition, physicochemical and mechanical properties of barley and rye flours

Finer barley and rye flours were produced by jet milling at two feed rates. The effect of reduced particle size on composition and several physicochemical and mechanical properties of all flours were evaluated. Moisture content decreased as the size of the granules decreased. Differences on ash and protein contents were observed. Jet milling increased the amount of damaged starch in both rye and barley flours. True density increased with decreased particle size whereas porosity and bulk density increased. The solvent retention capacity profile was also affected by jet milling. Barley was richer in phenolics and had greater antioxidant activity than rye. Regarding colour, both rye and barley flours when subjected to jet milling became brighter, whereas their yellowness was not altered significantly. The minimum gelation concentration for all flours was 16%w/v. Barley flour gels were stronger, firmer and more elastic than the rye ones.

Structural modification of bacterial cellulose fibrils under ultrasonic irradiation.

Ιn the present study we investigated ultrasounds as a pretreatment process for bacterial cellulose (BC) aqueous suspensions. BC suspensions (0.1-1% wt) subjected to an ultrasonic treatment for different time intervals. Untreated BC presented an extensively entangled fibril network. When a sonication time of 1min was applied BC fibrils appeared less bundled and dropped in width from 110nm to 60nm. For a longer treatment (3-5min) the width of the fibrils increased again to 100nm attributed to an entanglement of their structure. The water holding capacity (WHC) and ζ-potnential of the suspensions was proportional to the sonication time. Their viscosity and stability were also affected; an increase could be seen at short treatments, while a decrease was obvious at longer ones. Concluding, a long ultrasonic irradiation led to similar BC characteristics as the untreated, but a short treatment may be a pre-handling method for improving BC properties.

Emerging product formation

Abstract In the formulation of products composed of nutraceuticals and bioactive components, it is necessary to have the maximum protection of these sensitive ingredients along with targeted delivery systems in the right place at the right time. Conventional technologies have many limitations in this regard, whereas alternative emerging product formation techniques could be applied. Nanoencapsulation is one of the most popular emerging techniques applied at this stage of the Universal Recovery Process. Nanoencapsulation allows protection of the sensitive bioactive food ingredients from unfavorable environmental conditions, eradication of incompatibilities, solubilization, and masking of unpleasant taste and odor. This chapter reviews the nanoencapsulation techniques including nanocarrier systems and nanoemulsions as well as their recent applications in foods. Moreover, producing nanocrystals particularly from food waste materials is discussed as promising functional ingredient for both encapsulation purposes and formation of biodegradable composite films. In the last section, the pulsed fluidized bed agglomeration technique is presented as one of the most recent techniques for the encapsulation of bioactive compounds.

Encapsulation by nanoemulsions

Abstract Nanoemulsions are considered as ideal vehicles for nanoencapsulation of food bioactive ingredients and nutraceuticals. They serve as nanocarriers in many different materials as they are capable of improving water solubility and preventing the degradation of bioactive food components. Oil in water emulsions (O/W) can be used for the encapsulation of lipophilic active agents; on the other hand, water in oil emulsions (W/O) can be also used to encapsulate hydrophilic compounds including most polyphenols. In the current chapter, both simple emulsions (nano- and microemulsions) and double emulsions, as a potential encapsulation matrix, will be discussed; for readability we will use the term nanoemulsions for all emulsions with a droplet size of less than one micron.

Gluten-free bread: sensory, physicochemical, and nutritional aspects.

Publisher Summary Celiac disease affects approximately 1% of most populations but remains largely unrecognized, despite advances in diagnosis. Upon diagnosis, the celiac disease patient is directed to a gluten-free diet for life. The gluten-free diet excludes the intake of storage proteins found in wheat, rye, barley, and hybrids of these grains, such as kamut and triticale. It is to the benefit of celiac disease patients to develop new gluten-free products suitable to their needs that will increase their dietary choices and improve quality of life in general. New gluten-free products will increase the dietary choices of celiac patients or other nutritionally conscious consumers and improve their quality of life. Gluten-free ingredients employed in the formulation of gluten-free breads include maize; rice; amaranth; quinoa; starches of different origin; non-gluten proteins such as dairy proteins, gums, hydrocolloids, and their combinations; inulin; psullium; and gums (HPMC, locust bean gum, guar gum, carragenan, and xanthan gum). Fortified gluten-free breads, particularly those fortified with iron, meet the increased nutrient needs of celiac patients. Achieving desirable physicochemical and sensory characteristics for the gluten-free breads remains a challenge that drives continuous research in the field.

Gluten-Free Bread

Publisher Summary Celiac disease affects approximately 1% of most populations but remains largely unrecognized, despite advances in diagnosis. Upon diagnosis, the celiac disease patient is directed to a gluten-free diet for life. The gluten-free diet excludes the intake of storage proteins found in wheat, rye, barley, and hybrids of these grains, such as kamut and triticale. It is to the benefit of celiac disease patients to develop new gluten-free products suitable to their needs that will increase their dietary choices and improve quality of life in general. New gluten-free products will increase the dietary choices of celiac patients or other nutritionally conscious consumers and improve their quality of life. Gluten-free ingredients employed in the formulation of gluten-free breads include maize; rice; amaranth; quinoa; starches of different origin; non-gluten proteins such as dairy proteins, gums, hydrocolloids, and their combinations; inulin; psullium; and gums (HPMC, locust bean gum, guar gum, carragenan, and xanthan gum). Fortified gluten-free breads, particularly those fortified with iron, meet the increased nutrient needs of celiac patients. Achieving desirable physicochemical and sensory characteristics for the gluten-free breads remains a challenge that drives continuous research in the field.