Multi-scale changes of starch in type I sourdough fermentation system induced by wheat bran dietary fiber: from thermal properties, crystal structure, and in vitro digestibility behavior.

Effect of wheat bran dietary fiber on structural properties of wheat starch after synergistic fermentation of Lactobacillus plantarum and Saccharomyces cerevisiae

Soft wheat grains were treated with superheated steam (SS) at 165 and 190°C, respectively for 1–5 min to understand the changes in the structures and properties of wheat starch following SS treatment. The damaged starch contents, amylose ratio, gelatinization properties, surface morphology, viscosity, and crystalline structure of the starch in wheat flour were determined. Damaged starch content, amylose ratio, and starch viscosity significantly increased after SS treatment. The onset temperature (To) and peak temperature (Tp) of wheat starch increased with the extending of treatment time, while an opposite variation trend was observed for (Tc − To). Additionally, the gelatinization enthalpy (ΔH) decreased after 3–5 min of SS treatment. Starch aggregation was observed in scanning electron microscopy (SEM) graphs. Compared to traditional heat treatment methods, SS treatment of wheat grains may be preferable for modifying the starch properties of soft wheat since much time and energy could be saved.Practical ApplicationThe physicochemical properties and structure of soft wheat starch significantly affect the quality of cakes made with soft wheat flour. After SS treatment of wheat kernels, the amylose ratio and damaged starch content in wheat starch significantly increased. Moreover, gelatinization properties and starch viscosity of wheat starch were also significantly affected. The changes in physicochemical properties were mainly due to the changes in the structure of starch granules and starch molecules. The above results in the physicochemical properties and structure of starch led to the increase in the viscosity and gas retention capacity of cake batter, which might be the reason why the specific volumes and texture of cakes could be improved after SS treatment of wheat. This research verified SS treatment may be preferable for improving cake quality compared to traditional heat treatment methods, which promotes the application of SS in wheat process engineering.

The effect of non-thermal physical modification on the structure, properties and chemical activity of starch: A review

Effect of synergistic fermentation of Lactobacillus plantarum and Saccharomyces cerevisiae on thermal properties of wheat bran dietary fiber-wheat starch system

Interaction of wheat bran dietary fiber-gluten protein affects dough product: A critical review

Barley has been used to brew for centuries, mainly because it can provide a good source of starch, which is turned into fermentable sugars during mashing and then the sugars are substrate for the alcoholic fermentation that transforms wort into beer. Thus the ability to produce fermentable sugars is a desirable trait when selecting barley for brewing. However, the relations between barley starch structure and malt qualities have not been well studied. The objective of this research project is to develop an understanding of how starch structure in barley grains impacts malt qualities in different aspects. Starch in germinating barley grains is hydrolysed by endogenous amylolytic enzymes. This is crucial in malting and brewing as it partially degrades the starchy endosperm in the malt, which makes the malt more likely to produce sugars during mashing. However, the selection of barley for malting is currently based on empirical tests without fundamental understanding of the molecular changes of starch during germination. The grains from two barley varieties, low dormancy (Schooner) and moderate dormancy (Grimmett), were chosen in this study. The grains were germinated up to 8 days. Most Schooner grains germinated rapidly with shoots and roots visible after 2 days, whereas only a few Grimmett grains germinated. Grain samples were collected at 0, 2, 4, 6, and 8 days. The results of starch content test indicated a significant reduction of starch in the Schooner after 4 days, but no significant changes of starch content were observed in the Grimmett. Molecular size distributions of whole branched starch molecules and individual branches in the barley samples were obtained using size exclusion chromatography (SEC). Fluorophore-assisted capillary electrophoresis (FACE) and nuclear magnetic resonance (NMR) spectroscopy techniques were also used to obtain a detailed size distribution of the amylopectin branches and the degree of branching, respectively, of the starch in the samples. Near-infrared reflectance spectroscopy (NIRS) was used to analyse the samples in order to establish the relationship between the information of starch structure during germination obtained from SEC, FACE, NMR and that obtained from NIRS. The results show that shorter starch chains are degraded much faster than longer chains during germination. This is the first time such observation was made. Further study was carried out to investigate the mashing step of brewing. Sugar production is the most important aim of mashing. The sugar profile of wort after mashing is crucial to the quality of final beer product.There are several controlling factors in the production of fermentable sugars during mashing. Our results indicate that starch structure is one of the controlling factors, as different starch structural features lead to different enzymatic degradation rates, and thus affect the fermentability of wort. In order to study the role of starch structure in the production of fermentable sugars in wort, 9 different varieties of both barley malts and un-malted barley grains were used to undergo the mashing step. A number of commercial exogenous enzymes were added for un-malted samples. 20 portions of wort were then collected for sugar profile analysis using high-performance liquid chromatography. To characterize starch structure, the branched and debranched size distributions of starch molecules from the 20 barley malts and grains were obtained using SEC. Detailed chain length distributions of the samples were obtained through FACE. The structural characteristics of starch crystalline in the samples were described using X-ray scattering. The results indicated a significant correlation between structural characteristics of barley starch and the sugar profile of wort. Starch molecules with more short chains have a better sugar production during mashing, probably due to the fact that shorter starch chains are degraded much faster than longer ones given the same conditions. A third study was carried out to search for the potential correlations between starch structure and barley dormancy level. Nine barley varieties were selected for starch structure characterisation and dormancy level measurement. The results suggest certain correlations between starch fine structure and dormancy level of barley. However the statistical significance of the correlations are not enough to confirm any definite relations, which means either there is no correlations at all, or that the samples size in the third study is not big enough to provide a significant result. With the new knowledge about the role of starch structural in the process of beer brewing, we can provide brewers and breeders with improved methods to select or even grow more suitable barley for the beer they wish to produce.

The effects of wheat bran dietary fiber (WBDF) treated by air flow micro-pulverization on gelatinization, thermal, rheological, structural properties, and in vitro digestion of wheat starch (WS) were investigated. Different particle sizes of WBDF were obtained by conventional knife grinding and airflow micro-grinding. Compared with conventional knife grinding, the particle size of WBDF treated by air flow micro-pulverization decreased, the particle size distribution was concentrated at small particle sizes, the specific surface area increased, and the hydraulic and oil-holding power decreased, which was mainly related to the change of WBDF spatial structure and the increase of solubility. At the same time, the peak viscosity, setback, breakdown, and resistant starch content short-range order degree and relative crystallinity of WS were increased by adding WBDF treated by air flow micro-pulverization, whereas the gelatinization enthalpy value and apparent viscosity were decreased. This indicated that the air micro pulverized WBDF promoted gelatinization and inhibited digestion while reducing the thermal stability of WS, leading to short-term recovery. This study provides a theoretical reference for the production and processing of gluten-containing flour products. PRACTICAL APPLICATION: In this study, the physical and chemical properties and spatial structure of air flow micro pulverized dietary fiber of wheat bran were analyzed, and its effects on the properties of wheat starch were studied. Therefore, this study provides a theoretical basis for the industrial application of gluten-containing flour products.

A limited number of studies have been conducted on the effects of ozone use on cereal and its components. Starch, an important natural macromolecule, is an essential component of cereals. In present study, the effects of ozone on the structure, physico-chemical and microbiological properties of wheat, corn, potato and rice starches were investigated. Wheat starch, corn starch, potato starch and rice starch water mixtures were prepared in the ratio of 1:9 (dry sample to water ratio) and treated with ozone at a rate of 60 g/h for 1 hour, while unozonated samples were used as controls. Light microscopy represented that the structures of corn and potato starch samples were affected by 1 hr ozonation rather than the structures of wheat and rice starch samples. Colour of ozone-oxidized wheat, corn and potato starch samples could meet the consumer preference due to the higher lightness, higher whiteness and lower chroma value. However, high chroma, high yellownes and low whiteness values of ozonated rice starch is not adequate for consumer desire. Microbiological analysis showed that 1 hr ozonation reduced the total bacteria and mould/yeast counts significantly for all wheat, corn, potato and rice starch samples (P ＜ 0.05) due to most probably the reduced pH of samples. Ozonation can be an alternative modification technique, but further research is needed to understand the certain benefits and limitations of ozone applications on starch oxidation for human safety and health.

Physicochemical properties and structure of modified potato starch granules and their complex with tea polyphenols

Appropriate microwave improved the texture properties of quinoa due to starch gelatinization from the destructed cyptomere structure

Digestibility, physicochemical and structural properties of octenyl succinic anhydride-modified cassava starches with different degree of substitution

Insight into characteristics in rice starch under heat- moisture treatment: Focus on the structure of amylose/amylopectin

Insight in changes in starch and proteins molecular structure of non-wheat cereal flours influenced by roasting and extrusion treatments

Using Bainong 365 wheat starch as raw material, starch samples were preheated in a RVA to simulate DSC heating profiles. The thermodynamic properties, long-range orderliness, short-range orderliness, and structure of wheat starch were determined by DSC, XRD, FTIR, LF-NMR and SEM to explore the phase transformation mechanism of Bainong 365 wheat starch at different water contents. The results show that at different moisture contents, when the endothermic transition temperature of starch samples determined by DSC was reached or exceeded, the enthalpy of starch was 0, all free water was converted into uneasy flowing water and bound water, and the surface structure of starch was severely damaged. At this time, starch was completely gelatinized, but the short-range and long-range ordered structures of starch determined by FTIR and XRD still existed and gradually decreased with increasing temperature. Therefore, it was concluded that the temperature range of the starch endothermic transition does not represent the temperature range of complete gelation of starch, and the structure destroyed by complete gelation of starch may not be simple short-range and long-range ordered molecular structures.

SummaryThe effect of wheat bran dietary fibre (WBDF) on the texture and extensional properties of gluten (G) as well as gluten‐starch (G+S) doughs were investigated. Texture analysis revealed an increasing hardness of WBDF‐enriched doughs, ascribed to the gradual formation of intermolecular hydrogen bonds and weakened aggregation behaviour of gluten proteins. Extension results showed that G and G+S systems exhibited growing extension resistance thanks to the strengthened strain‐hardening capacity induced by WBDF. On the other hand, the WBDF accelerated the rupture of the gluten network and led to a downtrend of dough extensibility by increasing the friction with gluten branches and impairing the uniformity of the network structure. The findings indicate the possible impairment of the dough texture properties upon the addition of WBDF. Accordingly, for bran‐enriched flour products, the pretreatment with bran‐like particles leading to size reduction, softening or solubility improvement may be advantageous.