Multiphoton microscopy is a nondestructive label-free approach to investigate the 3D structure of gas cell walls in bread dough.

During the different steps of bread-making, changes in the microstructure of the dough, particularly in the gas cell walls (GCW), have a major influence on the final bread crumb texture. Investigation of the spatial conformation of GCWs is still a challenge because it requires both high resolutions and 3D depth imaging. The originality of the present work lies in the use of label-free non-destructive multiphoton microscopy (NLOM) to image the 3D structure of GCWs, shedding light on their behavior and organization in wheat bread dough. We demonstrated that second and third harmonic generation (SHG, THG) allow imaging, respectively, of starch granules and interfaces in bread dough, while the gluten matrix was detected via two-photon excitation fluorescence (TPEF). Last, a distinction between the gluten network and starch granules was achieved using gluten endogenous fluorescence (EF) imaging, while the position, size, and 3D orientation of starch granules in GCWs were determined from harmonic imaging, made possible by the acquisition of backward and forward SHG with linear polarization. These innovative experiments highlight the strengths of NLOM for a label-free characterization of bread dough microstructure for the first time, in order to understand the role of starch granules in dough stabilization.

Starch modification through environmentally friendly alternatives: a review.

Starch is a versatile and a widely used ingredient, with applications in many industries including adhesive and binding, paper making, corrugating, construction, paints and coatings, chemical, pharmaceutical, textiles, oilfield, food and feed. However, native starches present limited applications, which impairs their industrial use. Consequently, starch is commonly modified to achieve desired properties. Chemical treatments are the most exploited to bring new functionalities to starch. However, those treatments can be harmful to the environment and can also bring risks to the human health, limiting their applications. In this scenario, there is a search for techniques that are both environmentally friendly and efficient, bringing new desired functionalities to starches. Therefore, this review presents an up-to-date overview of the available literature data regarding the use of environmentally friendly treatments for starch modification. Among them, we highlighted an innovative chemical treatment (ozone) and different physical treatments, as the modern pulsed electric field (PEF), the emerging ultrasound (US) technology, and two other treatments based on heating (dry heating treatment - DHT, and heat moisture treatment - HMT). It was observed that these environmentally friendly technologies have potential to be used for starch modification, since they create materials with desirable functionalities with the advantage of being categorized as clean label ingredients.

Ozone technology to reduce zearalenone contamination in whole maize flour: degradation kinetics and impact on quality.

BACKGROUND: Maize is one of the most important cereals. It is used for different purposes and in different industries worldwide. This cereal is prone to contamination with mycotoxins, such as zearalenone (ZEN), which is produced mainly by Fusarium graminearum, F. culmorum and F. equiseti. Toxin production under highly moist conditions (aw > 0.95) is exacerbated if there are alternations between low temperatures (12-14 °C) and high temperatures (25-28 °C). Even if good production practices are adopted, mycotoxins can be found in several stages of the production chain. For this reason, an alternative to reducing this contamination is ozonation. This study evaluated the reduction of ZEN in naturally contaminated whole maize flour (WMF) treated with 51.5 mg L-1 of ozone for up to 60 min. Pasting properties, peroxide value, and fatty acid composition were also evaluated. RESULTS: Zearalenone degradation in ozonated WMF was described by a fractional first-order kinetic, with a maximum reduction of 62.3% and kinetic parameter of 0.201 min-1 in the conditions that were evaluated. The ozonation process in WMF showed a decrease in the apparent viscosity, a decrease in the proportion of linoleic, oleic, and α-linolenic fatty acids, an increase in the proportion of palmitic acid, and an increase in the peroxide value. CONCLUSION: Ozonation was effective in reducing ZEN contamination in WMF. However, it also modified the pasting properties, fatty acid profile, and peroxide value, affecting functional and technological aspects of WMF. © 2019 Society of Chemical Industry.

Combining ozone and ultrasound technologies to modify maize starch.

In this work, maize starch was modified using ultrasound (US) and ozone (O3) treatments, each one alone and also in combination. The starch molecular structure, granule characteristics and properties were evaluated. The US treatment alone did not show influence on the starch physical characteristics. On the other hand, the O3 treatment, alone or in combination with US, led to significant changes on starch molecules by increasing carbonyl and carboxyl groups and the apparent amylose content, while decreasing pH and the starch molecular size distribution. The granules' particle size distribution (PSD), their morphology and crystallinity were not affected by any of the treatments. Regarding the starch properties, water absorption index (WAI), water solubility index (WSI), pasting properties and gel strength were clearly more affected by the ozone treatment as compared with the ultrasound treatment. However, the paste clarity was significant higher when the combined treatments were applied, especially when US was used before O3. These results are prompting the hypothesis that the US treatment improved the subsequent action of O3.

Ozone technology as an alternative to fermentative processes to improve the oven-expansion properties of cassava starch.

Cassava starch has a remarkable importance in the food industry and it can be used either as ingredient or additive. The sour cassava starch is a product with a good oven-expansion capacity and several applications, being especially important as an alternative for gluten-based products. However, it is obtained through natural fermentation followed by solar drying, which hinders its production and application. In this context, this work proposed the ozone processing as an alternative to obtain cassava starch with good oven-expansion property. The effect of ozonation on starch granular and molecular structure was evaluated, as well as on the main starch properties. The ozone processing reduced the starch molecular size, also forming carbonyl and carboxyl groups. The structural changes led to pastes with higher clarity, better oven expansion and softer texture. The improvement in starch properties and technological aspects were related with the molecular changes. In conclusion, ozone oxidation was proved to be a viable and easier alternative for the conventional process.

Properties and possible applications of ozone-modified potato starch.

In this work, different properties of potato starch modified by ozone oxidation were evaluated and described aiming to represent different possibilities of industrial application. The most promising results were observed regarding the pasting properties and the gel texture of the starch samples ozonated for 15 and 30 min. These samples presented a higher apparent viscosity and a higher gel strength when gelatinized at 65 and 70 °C, if compared to the native sample. Furthermore, the 15 and 30-min samples retained more water at mild temperatures (~60 °C) than the other samples. These results could be related to the less compact structure of the oxidized starches after the ozone processing due to the cleavage of their glycosidic bonds and the presence of electronegative groups. Not only do these characteristics facilitate the water absorption and gelatinization of the samples at mild temperatures, they also favour the granular disruption at higher temperatures (above 85 °C). The data reported in this work broadens the understanding of the ozone-modification process, as well as suggesting possibilities of industrial applications using ozonated potato starch.

Irradiation of mung beans (Vigna radiata): A prospective study correlating the properties of starch and grains.

In this work, the effect of Gamma-irradiation was evaluated on the characteristics of mung bean (Vigna radiata) grains and starches, considering doses up to 5 kGy. For this purpose, the starch structure and properties were evaluated, as well as the grains' hydration, germination and cooking. The irradiation process was able to change the characteristics of both mung bean starches and grains. The starch structure was partially changed, presenting smaller molecules and small changes in the granule morphology. No alterations were observed in the starch X-ray diffraction pattern, while lower pH was achieved. Considering the starch properties, it was observed lower water retention ability at 75 °C, lower apparent viscosity, higher paste clarity and, in general, harder and less viscous gels. The ionizing radiation accelerated the hydration, reduced the germination capacity and improved cooking time of the mung bean grains. The results proved the efficacy of using ionizing radiation, at the doses applied in this work, to desirably modify the mung bean starch and grains.

Structure and properties of starches from Arracacha (Arracacia xanthorrhiza) roots.

Arracacha (Arracacia xanthorrhiza Bancroft) is an underexplored Andean root with a high starch content. In this work, starches from two different varieties of Peruvian arracacha were evaluated and characterized in relation to their granule morphology, molecular structure and properties. The starches presented round or polygonal shapes, with a mean diameter of ~20 µm and B-type granules. They were rich in amylopectin molecules with long chain lengths (with the ability to complex iodine) and some with intermediate sizes (indicating a defective crystalline structure). The starches presented low gelatinization temperature, enthalpy of gelatinization and tendency to retrogradation and high peak apparent viscosity and swelling capacity, even at moderate temperatures (60 °C), characteristics of high interest for industrial purposes. Besides, the starches presented a smooth and elastic gel and a high paste clarity. Overall, the arracacha roots presented attractive properties and can be used as an alternative botanical source for starch extraction.

Ozonation of whole wheat flour and wet milling effluent: Degradation of deoxynivalenol (DON) and rheological properties.

The objective of this study was to evaluate the reduction on the levels of the mycotoxin deoxynivalenol (DON) in whole wheat flour (WWF) with different moisture levels, on the wet milling effluent through ozone (O3) processing, as well as the impact of ozonation on the rheological properties of flour. The results have shown that the reduction of DON was improved with increasing moisture and exposure time of WWF and wet milling effluent to ozone. The maximum reduction was about 80%, proving that ozonation is an effective and promising technology in reducing mycotoxins in different products. However, the process altered the rheological profile of WWF. Therefore, further studies are needed to better understand the process.

Enhancing mung bean hydration using the ultrasound technology: description of mechanisms and impact on its germination and main components.

The ultrasound technology was successfully used to improve the mass transfer processes on food. However, the study of this technology on the grain hydration and on its main components properties was still not appropriately described. This work studied the application of the ultrasound technology on the hydration process of mung beans (Vigna radiata). This grain showed sigmoidal hydration behavior with a specific water entrance pathway. The ultrasound reduced ~25% of the hydration process time. In addition, this technology caused acceleration of the seed germination - and some hypothesis for this enhancement were proposed. Moreover, it was demonstrated that the ultrasound did not change both structure and pasting properties of the bean starch. Finally, the flour rheological properties proved that the ultrasound increased its apparent viscosity, and as the starch was not modified, this alteration was attributed to the proteins. All these results are very desirable for industry since the ultrasound technology improves the hydration process without altering the starch properties, accelerates the germination process (that is important for the malting and sprouting process) and increases the flour apparent viscosity, which is desirable to produce bean-based products that need higher consistency.