Effect of curdlan on the quality of frozen-cooked noodles during frozen storage

Frozen-cooked noodles (FCN) and its components undergo quality changes during frozen storage, such as reduced textural and cooking qualities, weakened gluten network, and damaged starch properties; thus, storage condition is a critical factor affecting the final quality of FCN. In this study, in view of the thermoirreversible high-strength gel property (at ≥ 80 °C) of curdlan, strong hydrophilicity, and freeze-thawed stability of high-strength gel prepared from curdlan powder, the effect of curdlan on the quality of FCN during frozen storage was first evaluated. The results showed that curdlan was effective in reducing cooking loss, enhancing water absorption, and improving textural properties of FCN; the improving effect presented a trend of first increasing and then decreasing with the amount of increasing curdlan (0.1%–0.9%); and the addition of 0.5% curdlan was most effective in improving the quality of FCN. Thermal gravimetric analysis indicated that curdlan enhanced thermal stability of FCN, implying curdlan could strengthen the gluten network. Meanwhile, structural observations revealed that, during frozen storage, FCN with added curdlan exhibited a more continuous and compact gluten network accompanied with more uniform and smaller ice crystals. Thus, curdlan is desirable to be used as a novel gum in FCN to provide specific functionality and minimize the negative effect of frozen storage. This study provides new insights into the quality improvement of FCN and further expands the application potential of curdlan in food industry.     

Low temperature increased the biosynthesis of 2-AP,cooked rice elongation percentage and amylose content percentage in rice

Rice fragrance, cooked rice elongation and amylose content are some of the traits used in determining rice grain quality. 2-acetyl-1-pyrroline (2-AP) is the major compound that is responsible for fragrance in rice.This experiment was conducted with two indica rice cultivars: Meixiangzhan 2 and Xiangyaxiangzhan. Three temperature-controlled chambers: High (32 °C from 06:00 to 17:59 and 26 °C from 18:00 to 05:59), medium (27 °C from 06:00 to 17:59 and 21 °C from 18:00 to 05:59) and low (22 °C from 06:00 to 17:59 and 16 °C from 18:00 to 05:59) were used for the study. At the onset of heading, both cultivars were transferred to the three temperature-controlled chambers. Our results showed that in both cultivars, low temperature growth had the highest 2-AP content, while high temperature growth recorded the lowest 2-AP content. Principal component analysis showed remarkable differences in the metabolomes of rice grown in high, medium and low regimes. In the grains of both cultivars, we observed significant reduction in 2-AP content after 6 and 9 months of storage, however; 2-AP retention differed greatly in both cultivars. We also reported that low temperature growth increased cooked rice elongation percentage and the biosynthesis of amylose in rice. In conclusion, our findings will provide more information to breeders working on the improvement of rice grain quality.     

Genotypic variations in zinc accumulation and bioaccessibility among wheat (Triticum aestivum L.) genotypes under two different field conditions

Zinc (Zn) is an essential micronutrient for human health. Breeding zinc-rich crop genotypes is considered as potential solution to Zn deficiency. In this study, variation of Zn uptake, accumulation, distribution and the estimated bioaccessibility among 30 wheat genotypes across two locations were investigated with field experiments. A significant difference in grain Zn concentrations occurred across the two locations, with the corresponding values of 55.24 and 57.14 mg kg⁻¹. Grain Zn concentration was significantly and positively correlated with grain Mn concentration (0.698**, 0.617** for two locations). The estimated grain Zn bioaccessibility also showed a significant difference, a trend similar to grain Zn concentrations but with lower values (13.87 and 13.49 mg Zn d⁻¹ for two locations). These results indicate that the interaction of locations * genotypes may play an important role in grain Zn concentrations and Zn bioaccessibility.     

Characterization and comparison of predominant aroma compounds in microwave-treated wheat germ and evaluation of microwave radiation on stability

The present study was performed to evaluate the effects of microwave (MW) output power and treatment time on moisture content, lipase and lipoxygenase activities as well as colour changes of wheat germ (WG). In addition, the key aroma compounds in different MW-power-treated WG, which is of importance to the flavour of WG products, were also investigated. The obtained results showed that MW treatment maintained the inherent colour of WG and significantly reduced the moisture content (maximum reduction of 95%) and the activities of lipase and lipoxygenase (maximum reduction of 65% and 99%, respectively). In terms of aroma compounds, with the increase of the MW output power, the content of esters, alkanes, alcohols and acids decreased, while the content of heterocyclic compounds, nitrogen-containing compounds, aldehydes and ketones increased, providing more compounds with roasted flavour and less volatiles with grass-like flavour. Therefore, MW treatment was an effective stabilization method for WG utilization.     

Characterization and bioactivities of young rice protein hydrolysates

Immature rice was reported to contain higher quantities of bioactive compounds than mature rice. Young rice protein is easy to digest and has hypoallergenic potential, with protein content of 7.2–11.5% compared to rice bran at 9.8%. Few studies have reported on bioactivities and characterization of young rice proteins and their hydrolysates. Bioactivities of native protein and protein hydrolysates of two rice varieties (white rice and colored rice) were characterized and investigated for four development stages (flowery, milky, dough, and mature). Degree of hydrolysis of young rice protein was considerably higher than at the mature stage. Highest DPPH and iron chelating activity were found in alcalase® protein hydrolysate during the flowery-to-milky stage. Iron chelating activity was constant in all development stages because of the low polar amino acid content in rice. The ACE activity of alcalase® protein hydrolysate was higher than native protein at the same development stage, as observed in the milky and dough stages. Inhibitory activity of young rice hydrolysate HepG2 cells was concentration-dependent and not correlated with protein molecular size.     

Localization of amino acids in germinated rice grain: Gamma-aminobutyric acid and essential amino acids production approach

Germinated rice is popularly consumed for its high gamma-aminobutyric acid (GABA) and bioactive compounds. Supporting information on how to germinate rice with high GABA content and essential amino acids is lacking. White and colored rough rice were germinated for 0, 24, 48, 72, 96, 120 and 144 h. GABA, GABA substrates and essential amino acids were also investigated using GC-MS and MALDI-MSI. GABA was more concentrated after germination and shifted into the coleoptile. High correlation was recorded between germination time and GABA (0.79–0.83, p ≤ 0.01) and glutamic acid (0.88–0.89, p ≤ 0.01). Highest rates of GABA and glutamic production were observed within 48 h of germination in both rice varieties (26.12 and 34.28 mg/100g) and reached maximum value at 96 h (31.36 and 38.75 mg/100g). Colored rice germination showed higher GABA, GABA substrates and deficient amino acids than white rice. GABA and essential amino acids drastically increased after germination, supporting the consumption of germinated rice as a functional food.     

Development of a limited-water soaking method on the fortification of rice with calcium and iron by parboiling

Fortifying rice using parboiling has been shown to have a higher retention rate of nutrients and acceptable sensory characteristics. However, the conventional soaking step employs excess water and therefore generates large amounts of wastewater containing nutrients that, when discarded without treatment, can lead to nutrient overload in soil. A limited-water soaking method to fortify rice with calcium and iron by parboiling was developed and evaluated. Fortified rice quality attributes, mineral contents, the amount of wastewater, total solids in wastewater, washing-retention and bioavailability of calcium and iron were determined and compared with properties of rice that was fortified in excess-water soaking. The limited-water soaking method on average reduced the amount of effluent by 89% and the amount of total solids in wastewater by up to 85%. Rice fortified by the limited-water soaking method showed similar color and head rice yield, and slightly lower mineral uptakes compared to conventional soaking. Rice fortified simultaneously with calcium and iron in limited-water soaking contained about 999 mg Ca and 33 mg Fe per kg milled rice, and approximately 66% of calcium and 71% of iron remained in the rice after simulated washing. Calcium and iron dilute HCl-solubility was not affected by the soaking condition. Therefore, the limited-water soaking method can reduce the cost of fortification and wastewater treatment without affecting rice quality attributes.     

Variation in physicochemical properties and nutritional quality in chalky mutants derived from an indica rice

The physicochemical and nutritional quality of four chalky mutants (JM1-4) rice and their parent 93-11 were investigated. JM1 and JM4 are white-belly mutants, and JM2 is white-core mutant, while JM3 is floury mutant. JM2 is also a high amylose mutant with AAC of 29%. JM3 had the lipid content nearly three times of the parent, so it is also a high lipid mutant. JM1 had similar pasting viscosities with the parent, while JM2 and JM3 had smaller breakdown and setback than 93-11. JM2 had lower enthalpy of gelatinization, but higher enthalpy of retrogradation, so it had highest retrogradation percentage. JM3 had the highest accumulation of amino acids, fatty acids, and some major mineral elements such as P, K, Mg and Ca. The amino acids and fatty acids had negative correlation with PV, HPV and CPV. The pleiotropic effects caused by the mutations on starch and lipid metabolism deserve further investigation.     

Contributions of individual and combined Glu-B1x and Glu-B1y high-molecular-weight glutenin subunits to semolina functionality and pasta quality

Durum wheat is an important food crop used primarily for pasta production. High-molecular-weight glutenin subunits (HMW-GS) encoded by the closely linked genes Glu-B1x and Glu-B1y are known for their combined effects on pasta quality, but their individual contributions and interactions remain poorly understood. In this study, we show that individual loss-of-function mutants of Glu-B1x (ΔBx6) and Glu-B1y (ΔBy8) were associated with significant reductions in gluten strength compared to the wildtype, with stronger effects in the ΔBxy double mutant. Reductions in gluten strength were reflected in reduced mixograph and alveograph parameters, gluten index, faster extrusion flow rates and increased cooking loss. Interestingly, the Glu-B1x mutation was also associated with significant increases in grain and semolina protein content, increased pasta firmness, reduced starch viscosity and increased amylose in ΔBx6 and ΔBxy. In general, the ΔBx6 mutation had stronger effects than the ΔBy8 mutation, and significant interactions between the two genes were frequent. In addition to the basic knowledge gained on the individual effects of the Bx6 and By8 subunits and their interactions, the genetic stocks developed in this study provide useful tools to study the effects of natural or synthetic HMW-GS on pasta quality parameters in a background lacking endogenous HMW-GS.     

Gluten proteome comparison among durum wheat genotypes with different release date

In order to deepen insight into durum wheat prolamin composition in relation to both end use quality and gluten related disorders, a phenotyping of four genotypes of different release date and technological performance was carried out. A proteomic approach integrated with the evaluation of protein aggregation level, amino acid composition and reactivity to G12 monoclonal antibody, was adopted. The degree of polymerization, estimated as unextractable polymeric proteins (UPP), was positively influenced by Cys-rich proteins (Glu-B3 LMW-GS), with Saragolla showing up to 40% higher values than other genotypes. The proteomic assessment allowed to identify proteins involved in gluten related disorders. In particular, ω5-gliadin involved in wheat allergy (WA), resulted markedly over-expressed in the old landrace Dauno III, up to four-fold than in modern Saragolla. A marked influence of genotype on the expression level of gliadins containing toxic epitopes (TECP) was observed with the more recent genotypes showing lower values (−53%). Also, reactivity to G12 moAb resulted higher in the two old genotypes consistently to their higher celiac disease (CD) toxicity evaluated by the proteomic approach. In conclusion a better gluten composition for processing seems to be associated to a lower expression level of CD toxic peptides and Tri a 19.     

Soluble arabinoxylans extracted from soft and hard wheat show a differential prebiotic effect in vitro and in vivo

Arabinoxylans (AX) are part of dietary fiber. They are currently under study due to their potential prebiotic effect. Wheat whole grain flours contain all the grain layers and, therefore, present a higher arabinoxylan content than white flour. It is known that the chemical structure of these compounds varies with the type of wheat cultivar and the tissue from which they are extracted. In this work, water soluble extractable arabinoxylans (WE-AX) from two types of wheat whole flours (hard and soft) were extracted. We characterized the molecular size distribution and the potential prebiotic effect of those extracts. The prebiotic effect was evaluated in vitro and confirmed in vivo. Bacterial group abundance (Lactobacillus, Bifidobacterium, Clostridium, Enterococcus, Bacteriodes and total bacteria) was determined by quantitative RT-PCR. The molecular size of AX from hard wheats was significantly higher than AX from soft wheats. Both extracts showed potential prebiotic activity by increasing the growth of beneficial bacteria in vitro and in vivo, decreasing the pathogens in the profile of intestinal microorganisms and increasing the amount of short chain fatty acids in the intestine. WE-AX from hard wheat showed a higher prebiotic activity. Prebiotic effect assessed in vitro and in vivo assays showed a significant correlation between both types of analysis. This finding suggests that the in vitro indices performed allow predicting the potential prebiotic effect in vivo.     

Effect of zein extrusion and starch type on the rheological behavior of gluten-free dough

Previous research has shown that zein, above its glass transition temperature, may adopt molecular structures that are able to form doughs with viscoelastic properties comparable to those of wheat gluten. It is hypothesized that extrusion can promote molecular changes in zein and favor interactions with starch that enhance dough viscoelasticity. Thus, the effects of extruding zein at 90–160 °C on the rheological properties of doughs prepared with potato, rice, and maize starches were determined.Formulations were optimized to provide similar mixing profiles to that of a standard wheat dough. For all zein samples, creep-recovery tests demonstrated that doughs prepared with maize and potato starches were less elastic when compared to doughs prepared with rice starch. Zein doughs produced using rice starch were comparable to wheat-dough. Extensional tests showed that zein extruded at 160 °C provided a larger increase in strain-hardening behavior, which is important for bread production. These samples also exhibited larger extensional stresses. Gel electrophoresis of zein extruded at 160 °C revealed an increase in protein aggregates and the presence of smaller peptides when compared to samples subjected at lower extrusion temperatures.Scanning electron micrographs of doughs containing zein showed starch granules embedded within an amorphous material and fibrous structures, which is attributed to elongated zein.     

New angiotensin-converting enzyme inhibitory peptide from Coix prolamin and its influence on the gene expression of renin-angiotensin system in vein endothelial cells

Coix seed, which is a traditional Chinese medicine, has been used to treat hypertension for thousands of years. It has been shown that Coix prolamin peptides display high levels of angiotensin I converting enzyme (ACE) inhibitory activity. Hence, we purified the ACE inhibitory peptides from Coix prolamin hydrolysates and evaluated the influence of the most potent peptide on the renin-angiotensin system (RAS) genes expression in human umbilical vein endothelial cells (HUVECs). In this study, Coix prolamin peptides were sequentially separated by ultrafiltration, ion exchange chromatography, gel filtration chromatography and RP-HPLC, while the peptide structure was analyzed by mass spectrometry. Next, in silico proteolysis, pharmacophore and molecular docking were further applied to screen and optimize the structure of peptides. Finally, a novel ACE inhibitory peptide VDMF was obtained, in which its influence on the gene expression of RAS signaling pathway in AngⅡ-injury HUVECs was evaluated by quantitative real-time PCR. VDMF significantly down-regulated ACE, AngII type 1 receptor (AT1R) and ACE2 mRNA expression in comparation with model group, while up-regulating Mas gene expression. Hence, we obtained a novel antihypertensive candidate that was derived from the Coix peptides, which could involve a multi-modulation mechanism that regulates blood pressure.     

Simultaneous fortification of rice with folic acid and β-carotene or vitamin A by limited-water parboiling

Rice fortification by parboiling has been used to fortify rice with a single or a combination of multiple nutrients. While several studies have demonstrated the success of rice fortification with minerals by the parboiling technique, the number of studies that used vitamins as fortificants is limited with varying results. A limited-water soaking method has been introduced as a feasible and more sustainable alternative to the conventional excess-water soaking in parboiling. This study investigated the application of limited-water soaking in the simultaneous fortification of rice with water- and fat-soluble vitamins. Pure and water-soluble forms of β-carotene and vitamin A were first compared to identify a more effective form to be combined with folic acid. Water-soluble forms of β-carotene and vitamin A were easy to incorporate into the soaking water and presented effective fortification without affecting rice milling quality, the amount of wastewater and solids in wastewater. Milled rice fortified with folic acid combined with water-soluble forms of β-carotene or vitamin A in the limited-water soaking method contributed to about 75% of the recommended dietary allowances (RDAs) for folic acid, about 173% (female) and 134% (male) of the RDAs for β-carotene, and to about 58% (female) and 45% (male) of the RDAs for vitamin A. Rice fortified with β-carotene showed a greater uptake and a more orange color compared to the others. Thus, fortification of rice with vitamins by limited-water parboiling is an efficient process to obtain fortified rice that can significantly increase vitamin intake with limited environmental impacts.     

Quantitative LC-MS proteoform profiling of intact wheat glutenin subunits

Methodology for the quantitative analysis of intact glutenin proteins by ESI-LC-MS was developed with 1 Da mass resolution, constituting the first published application of proteoform profiling to plant biology. Two parent lines and 28 F5 crosses were analyzed in two blocks, 14 months apart. Control sample data were used to align retention times and normalize abundance between sample sets. A total of 4622 observations of 347 distinct proteoforms between 17 899 and 88 744 Da were observed. Proteoform abundances spanned a 1000-fold range and were linear (r² > 0.990) with dilution. A novel method for the objective elimination of low intensity, noise-dominated data using replicate variability within the dataset is presented. Two abundant PTMs were detected; one known but uncharacterized Bx and Dy high-molecular-weight glutenin subunit (HMWGS) PTM and the other in 24 low molecular weight proteoform pairs. Finally, 16 abundant proteoforms were detected in progeny but not in either parent. This application should increase the statistical power of correlations between gluten complement and functional data and drive the detection of novel PTMs that may indicate differential regulation of the cellular processes related to quality.     

Impact of ethanol,succinic acid,and the combination thereof at levels produced during sponge fermentation on hard wheat,soft wheat,and durum wheat farinograph rheology

The sponge and dough mixing process is one of the most common in the world, yet the mechanistic understanding of this process has yet to be sufficiently explored. In this study, aqueous solutions of ethanol, succinic acid, and their combination were prepared at concentrations intended to replicate fermentation times of 3, 4 and 6 h. These solutions were added to a farinograph mixer to make dough using hard wheat, soft wheat, and durum wheat flour. The results indicate that these yeast metabolites (ethanol, succinic acid) impact the mixing resistance, peak mixing value, and dough mixing stability in each of the flour types, likely primarily affected by the ratios of gliadin to glutenin and LMW glutenin in each flour type. Results suggest a stabilizing non-covalent interaction imparted by gliadin at peak mixing time, a stabilizing effect of HMW glutenin during break down, and synergistic effects of ethanol and succinic acid that leads to a faster rate of breakdown in later stages of mixing. It also suggests an increase in mixing resistance when acidulants are added to durum wheat dough. Taken together, this study adds new insights on the sponge and dough mixing process in a way that has not previously been conducted.     

Spatial distribution of functional components in the starchy endosperm of wheat grains

The starchy endosperm of the mature wheat grain comprises three major cell types, namely sub-aleurone cells, prismatic cells and central cells, which differ in their contents of functional components: gluten proteins, starch, cell wall polysaccharides (dietary fibre) and lipids. Gradients are established during grain development but may be modified during grain maturation and are affected by plant nutrition, particularly nitrogen application, and environmental factors. Although the molecular controls of their formation are unknown, the high content of protein and low content of starch of sub-aleurone cells, compared to the other starchy endosperm cells types, may result from differences in developmental programming related to the cells having a separate origin (from anticlinal division of the aleurone cells). The gradients within the grain may be reflected in differences in the compositions of mill streams, particularly those streams enriched in the central and outer cells of the starchy endosperm, respectively, allowing the production of specialist flours for specific end uses.     

Effects of wheat tempering and stone rotational speed on particle size,dough rheology and bread characteristics for a stone-milled weak flour

The poor technological performance of weak wheat flours means that they are usually considered difficult to be transformed into satisfactory bread. During milling, there are several settings that can affect flour characteristics. In this study, we tested two operative parameters that have the potential to affect flour quality – stone rotational speed and wheat tempering. Tempering moistures were set at 11%, 13%, 15%, and 17%, while stone rotational speeds were set at 173, 260, and 346 rpm. Both factors were found to affect operative milling parameters, notably flour yield, process productivity and specific energy consumption. Grain moisture had a significant effect on both dough rheology and bread characteristics (dough stability, tenacity, and extensibility). Dough stability was maximum at 13% moisture. Dough tenacity decreased as moisture increased, while extensibility increased as moisture increased. Bread specific volume and crumb specific volume were improved at 13% and 15% moisture. In conclusion, wheat tempering can be used to improve the potential of a weak flour and bread characteristics, while stone rotational speed affects operative parameters and white flour yield.     

GlutoPeak parameters of whole wheat flours for gluten quality evaluation in soft wheat breeding programs

In soft wheat breeding programs, the gluten strength of flours from specific genotypes is determined by various chemical and rheological tests. Based on such tests, the experimental wheat lines with very weak flour gluten are typically selected for the production of soft-dough biscuits, while the lines with medium gluten strength and extensibility are reserved for hard-dough biscuits. Often, the genotypes having high gluten strength are removed from such breeding programs. In the present study, the usability of the GlutoPeak tester on whole wheat flour samples was investigated for assessing the gluten strength of soft wheat breeding materials. In the study, 25 soft wheat genotypes, grown in seven locations for three years, were categorized by commonly used gluten-quality-related parameters. Based on the results of the study GlutoPeak whole wheat flour PMT values ranging from 30.0 to 50.0 s and AM values from 15.0 to 20.0 GPU were found to be suitable for soft-dough biscuit products, whereas the values between 40.0 and 60.0 s and 20.0 and 23.0 GPU were appropriate for hard-dough biscuit products. The genotypes exhibiting AM values > 24.0 GPU and PMT values > 60.0 s were judged to have too-strong gluten, and thus eliminated from the breeding program. The gluten aggregation energy (AGGEN), and the torque after the maximum torque (PM) values were only useful and applicable to flours for soft-dough products. The maximum torque (BEM) values were not effective in discriminating against the genotypes. The results of this study demonstrated that the GlutoPeak whole wheat PMT and AM parameters can be recommended as quick and accurate parameters especially for early generation screening with small-scale tests in soft wheat improvement programs.     

Mass spectrometry imaging of BARLEYmax fructooligosaccharides

BARLEYmax is a novel hull-less barley cultivar lacking activity of a key enzyme required for starch synthesis (SSIIa), resulting in a grain with reduced total starch, higher dietary fiber, and higher fructan content. In this study, we examined the quantitative differences in fructan among 2 hull-less barley lines (BARLEYmax and Mannenboshi) and 2 peeled barley lines (Glutinous barley rice and Hindmarsh). We found that BARLEYmax had a higher fructan content, particularly 2 types of fructooligosaccharides (FOS), namely kestose and nystose, the important components of fructan that have some beneficial effects for human health. We established a mass spectrometry imaging (MSI) method to further investigate the content and localization of FOS in the barley lines. We found that kestose, nystose, and fructosyl-nystose showed increased molecular ion intensities in BARLEYmax compared with those in other barley lines. These results confirmed that the loss of SSIIa activity in BARLEYmax leads to a decrease in starch in the cytoplasm and an increase in fructan in the vacuole as an energy store. Overall, these findings demonstrate that MSI analysis is helpful for understanding FOS localization in cereal grains and for visual comparison among matured grains.