Amylolysis of large and small granules of native triticale, wheat and corn starches using a mixture of α-amylase and glucoamylase

Cereal flours with Bacillus coagulans and beta-glucan: Technological properties and sensory acceptability

This study aimed to develop three formulations of cereal flours: control cereal flour (CCF), probiotic cereal flour (PCF), and symbiotic cereal flour (SCF), and porridges from the flours were manufactured as a functional food. No significant differences were observed in the microbiological quality and the color of the flours for 150 days. The technological and functional potential of the flours were variously improved with the addition of Bacillus coagulans as a probiotic and beta-glucan as a prebiotic. The addition of beta-glucan fiber did not change the viability of the probiotic, which was higher than 7.45 log CFU/g for SCF and 7.13 log CFU/g for PCF until the end of the storage period. All porridge samples showed non-Newtonian fluid behavior with pseudoplastic characteristics; and the PCF and SCF porridges differed regarding the parameters of hardness (1.10 to 1.38 N), adhesiveness (5.88 to 8.86 mJ), cohesiveness (0.78 to 0.95) and gumminess (0.93 to 1.52 N) over time. The addition of the beta-glucan prebiotic interfered with these attributes due to its gelling capacity in the presence of water. The PCF obtained the best sensory acceptance scores when compared to the other formulations. The addition of Bacillus coagulans and beta-glucan did not interfere with thermographic behavior. The SCF differed in the observed crystallinity parameters from CCF and PCF, with the presence of larger solids and agglomerates.

Feasibility of replacing waxy rice with waxy or sweet-waxy corn viewed from the structure and physicochemical properties of starches

To explore the feasibility of substituting waxy rice with waxy or sweet-waxy corn, eight varieties of waxy and sweet-waxy corns were selected, including three self-cultivated varieties (Feng nuo 168, Feng nuo 211, and Feng nuo 10). Their starches were isolated and used as research objects, and commercially available waxy rice starch (CAWR) and waxy corn starch (CAWC) were used as controls. X-ray diffraction, scanning electron microscopy, differential scanning calorimetry, rapid viscosity analyzer, and rotational rheometer were used to analyze their physicochemical and structural characteristics. The morphologies of all corn starch granules were generally oval or round, with significant differences in particle size distributions. All ten starches exhibited a typical A-type crystal structure; however, their relative crystallinity varied from 20.08% to 31.43%. Chain length distribution analysis showed that the A/B ratio of Jing cai tian nuo 18 and Feng nuo 168 was similar to that of CAWR. Peak viscosities of corn starches were higher than that of CAWR, except for Feng nuo 10, while their setback values were lower than that of CAWR. Except for Feng nuo 10, the paste transparency of corn starches was higher than that of CAWR (10.77%), especially for Jing cai tian nuo 18 (up to 24%). In summary, Jing cai tian nuo 18 and Feng nuo 168 are promising candidates to replace CAWR in developing various rice-based products.

Isolation and characterization of natural nano starch from amaranth starch

Nano starch exhibits many advantages for application in diverse fields. Amaranth starch consisted of starch particle aggregates, isolated amaranth starch, and few natural nano starch (NNS), while NNS (0.92 ± 0.12 μm) was successfully isolated for the first time. Compared with the isolated amaranth starch, NNS showed smaller particle size but larger molecular weight, suggesting that the molecules arranged densely. NNS had a weak A-type crystal structure because of its more content of short starch chains, but higher amylose content resulted in the increase of its gelatinization temperature. The special NNS, owning several different physicochemical properties from amaranth starch, can open new ways for the production and application of nano biomass materials.

Effects of explosion puffing on the native structural organization and oil adsorption properties of starch

The effects of explosion puffing (EP) on the native structural organization (i.e., thermal properties, crystalline structure, short-range order, granule morphology and powder properties) and oil adsorption properties of puffed starch (PS) were investigated. The results showed that EP treatment could decrease the melting enthalpy of starch double helices and increase the V-type crystallinity. The highest V-type crystallinity (24.7 %) was obtained when the puffing pressure was 0.4 MPa and the starch:ethanol:water ratio was 1:2:1 (w/w). By controlling the puffing conditions, EP treatment can alter the morphology, and increase the particle size, flowability and specific surface area of PS. The high amorphous proportion and porous sheet structure of PS resulted in the highest oil adsorption capacity when the starch:ethanol:water ratio was 1:1:1 (w/w). Pearson correlation analysis showed that oil adsorption capacity was significantly and positively correlated with the 1022/995 cm-1 value and V-type crystallinity, but negatively correlated with bulk density and angle of repose. Furthermore, oil retention capacity was strongly dependent on V-type crystallinity. These findings demonstrated that EP is an innovative technology with the potential to enhance the V-type crystallinity and adsorption performance of starch.

Oil structuring from porous starch to powdered oil: Role of multi-scale structure in the oil adsorption and distribution

Oil structuring from porous starch is a potential alternative for the industrial production of powdered oil, but their relationship between starch multi-scale structure and oil adsorption characteristics was not clear. This study compared the role of multi-scale structure of porous starch (PS) prepared by normal and waxy maize starch in the oil adsorption. Waxy maize porous starch exhibited higher oil adsorption capacity (32.43 %-98.71 %) and more oil distributed on the surface of granules than normal maize porous starch, resulting from the more pores, larger specific surface area (1.01-1.53 m2/g), and pore size (8.45-9.32 nm). The enzymolysis time of native starch dominated oil distribution, leading to different granule adhesion and aggregation state. Pearson correlation analysis further showed oil adsorption capacity was negatively correlated with particle size, but positively correlated with enzymolysis rate and specific surface area of PS. The formation of powdered oil was mainly through the physical adsorption, including surface adsorption and pore adsorption. These findings could provide a promising route for the preparation of powdered oil with controlled multi-scale structure of PS.

Starch granules and their size distribution in wheat: Biosynthesis, physicochemical properties and their effect on flour-based food systems

Starch is a vital component of wheat grain and flour, characterized by two distinct granule types: A-type starch (AS) with granules larger than 10 µm in diameter, and B-type starch (BS) with granules measuring no more than 10 µm in diameter. This review comprehensively evaluates the isolation, purification, and biosynthesis processes of these types of granules. In addition, a comparative analysis of the structure and properties of AS and BS is presented, encompassing chemical composition, molecular, crystalline and morphological structures, gelatinization, pasting and digestive properties. The variation in size distribution of granules leads to differences in physicochemical properties of starch, influencing the formation of polymeric proteins, secondary and micro-structures of gluten, chemical and physical interactions between gluten and starch, and water absorption and water status in dough system. Thus, starch size distribution affects the quality of dough and final products. In this review, we summarize the up-to-date knowledge of AS and BS, and propose the possible strategies to enhance wheat yield and quality through coordinated breeding efforts. This review serves as a valuable reference for future advancements in wheat breeding.

Novel Design of an α-Amylase with an N-Terminal CBM20 in Aspergillus niger Improves Binding and Processing of a Broad Range of Starches

In the starch processing industry including the food and pharmaceutical industries, α-amylase is an important enzyme that hydrolyses the α-1,4 glycosidic bonds in starch, producing shorter maltooligosaccharides. In plants, starch molecules are organised in granules that are very compact and rigid. The level of starch granule rigidity affects resistance towards enzymatic hydrolysis, resulting in inefficient starch degradation by industrially available α-amylases. In an approach to enhance starch hydrolysis, the domain architecture of a Glycoside Hydrolase (GH) family 13 α-amylase from Aspergillus niger was engineered. In all fungal GH13 α-amylases that carry a carbohydrate binding domain (CBM), these modules are of the CBM20 family and are located at the C-terminus of the α-amylase domain. To explore the role of the domain order, a new GH13 gene encoding an N-terminal CBM20 domain was designed and found to be fully functional. The starch binding capacity and enzymatic activity of N-terminal CBM20 α-amylase was found to be superior to that of native GH13 without CBM20. Based on the kinetic parameters, the engineered N-terminal CBM20 variant displayed surpassing activity rates compared to the C-terminal CBM20 version for the degradation on a wide range of starches, including the more resistant raw potato starch for which it exhibits a two-fold higher Vmax underscoring the potential of domain engineering for these carbohydrate active enzymes.

Starch granular size and multi-scale structure determine population patterns in bivariate flow cytometry sorting

Bivariate flow cytometry (FC) sorting with forward scatter (FSC) and side scatter (SSC) is a recently established novel technique to separate starch granules. However, the forming mechanism of starch FC-dependent population patterns (i.e. the number of subgroups (NS) and FSC/SSC-dependent distribution patterns) remain partly elusive. For this, the correlation of granular size and multi-scale structure of native starches and FC-dependent population patterns was investigated through employing a wide range of native starches originating from different species involving cereal-, pulse-, and tuber crops. Results showed NS was pertinent with particle size, amylose content (AC), amylopectin chains length distribution, lamellar structure, short-range ordered structure. The distinct NS was determined by impacts of native starch FSC / SSC-dependent distribution patterns. Specifically, starch granular size significantly correlated with both FSC and SSC-dependent distribution patterns. The proportion of chains with DP 6-12 was the intra-molecular decisive factor to influence short-range ordered structure, finally leading to FSC-dependent distribution patterns. By contrast, AC was another intra-molecular index to determine SSC-dependent distribution patterns through affecting lamellar structure and short-range ordered structure.

Histological Evaluation of Cassava Starch/Chicken Gelatin Membranes

The use of biopolymers for tissue engineering has recently gained attention due to the need for safer and highly compatible materials. Starch is one of the most used biopolymers for membrane preparation. However, incorporating other polymers into starch membranes introduces improvements, such as better thermal and mechanical resistance and increased water affinity, as we reported in our previous work. There are few reports in the literature on the biocompatibility of starch/chicken gelatin composites. We assessed the in vivo biocompatibility of the five composites (T1–T5) cassava starch/gelatin membranes with subdermal implantations in biomodels at 30, 60, and 90 days. The FT-IR spectroscopy analysis demonstrated the main functional groups for starch and chicken gelatin. At the same time, the thermal study exhibited an increase in thermal resistance for T3 and T4, with a remaining mass (~15 wt.%) at 800 °C. The microstructure analysis for the T2–T4 demonstrated evident roughness changes with porosity presence due to starch and gelatin mixture. The decrease in the starch content in the composites also decreased the gelatinization heats for T3 and T4 (195.67, 196.40 J/g, respectively). Finally, the implantation results demonstrated that the formulations exhibited differences in the degradation and resorption capacities according to the starch content, which is easily degraded by amylases. However, the histological results showed that the samples demonstrated almost complete reabsorption without a severe immune response, indicating a high in vivo biocompatibility. These results show that the cassava starch/chicken gelatin composites are promising membrane materials for tissue engineering applications.

Mashing performance as a function of malt particle size in beer production

Significant innovations have occurred over the past 50 years in the malting and brewing industries, focused on optimization of the beer mashing, boiling and fermentation processes. One of the challenges faced in beer brewing has been in the malting process to obtain the desired malt and wort quality to produce high-quality beer products. The hydrolytic enzymes produced during grain germination are mostly entrapped inside the cellular matrices of the grain. The intra-grain diffusion of enzymes for in-situ hydrolysis, as well as diffusion of enzymes to wort, depends upon the malt size and malt size fractions obtained after milling. This review investigates the relationship between varying barley grain particle size distribution and the efficiency of the malting and mashing processes. Recommended ideal particle size of barley grain before and after milling are proposed based on the review of existing literature. Each brewing batch of grains with a proportion of >80% plump grains (>2.5 mm in size) is suggested to be the optimal size before milling, whereas the optimum grain particle size after milling ranged between 0.25 and 0.5 mm. The current review will summarize the theoretical aspects for malt milling and the particle size characteristics for optimizing the brewing process.

Methods for characterizing the structure of starch in relation to its applications: a comprehensive review

Starch is a major part of the human diet and an important material for industrial utilization. The structure of starch granules is the subject of intensive research because it determines functionality, and hence suitability for specific applications. Starch granules are made up of a hierarchy of complex structural elements, from lamellae and amorphous regions to blocklets, growth rings and granules, which increase in scale from nanometers to microns. The complexity of these native structures changes with the processing of starch-rich ingredients into foods and other products. This review aims to provide a comprehensive review of analytical methods developed to characterize structure of starch granules, and their applications in analyzing the changes in starch structure as a result of processing, with particular consideration of the poorly understood short-range ordered structures in amorphous regions of granules.

Starch granule size: Does it matter?

Nature has developed starch granules varying in size from less than 1 μm to more than 100 μm. The granule size is an important factor affecting the functional properties and the applicability of starch for food and non-food applications. Within the same botanical species, the range of starch granule size can be up to sevenfold. This review critically evaluated the biological and environmental factors affecting the size of starch granules, the methods for the separation of starch granules and the measurement of size distribution. Further, the structure at different length scales and properties of starch-based on the granule size is elucidated by specifying the typical applications of granules with varying sizes. An amylopectin cluster model showing the arrangement of amylopectin from inside toward the granule surface is proposed with the hypothesis that the steric hindrance for the growth of lamellar structure may limit the size of starch granules.

Impact of Particle Size on the Rheological Properties and Amylolysis Kinetics of Ungelatinized Cassava Flour Suspensions

The effect of particle size on enzymatic hydrolysis of cassava flour at subgelatinization temperature was investigated. A multiscale physical metrology was developed to study the evolution of different physical-biochemical parameters: rheology, granulometry, and biochemistry. In this study, four fractions of cassava flour based on the particle sizes under 75 µm (CR075), 75–125 µm (CR125), 125–250 µm (CR250), and 250–500 µm (CR500) were screened for enzymatic hydrolysis effect. The results showed that all cassava flour suspensions exhibited a shear-thinning behavior, and the viscosity increased drastically with the increase of particle size. During hydrolysis, the viscosity reduced slightly and the non-Newtonian behavior became negligible beyond 4 h of the process. The particles size for CR075 and CR125 increased steadily in diameter mean. The samples of CR250 and CR500 showed more fluctuation by first decreasing, followed by increasing in particle sizes during the process. The highest hydrolysis yield was found for samples with particle size under 125 µm (89.5–90.7%), suggesting that mechanical treatment of cassava can enhance the bioconversion rate.

Structural features of five types of maize starch granule subgroups sorted by flow cytometry

Subgroups of starch granules from five maize phenotypes including waxy-, normal-, popcorn-, sweet corn- and high-amylose maize were sorted by flow cytometry (FC) utilizing the side scatter channel (SSC) and forward scatter channel (FSC). SSC and FSC mainly reflecting internal object complexity, and object size, respectively. Subgroups with higher FSC signal always showed higher SSC signal, indicating larger granules exhibited higher internal structural complexity. Wide-angle and small-angle X-ray scattering analysis showed that the subgroups showing high SSC signal intensity also had high lamellar scattering intensity, and low crystallinity. Vibrational transitions of bonds analyzed by Fourier Transform Infrared Spectroscopy (FT-IR) showed that the subgroups of maize starches, except sweet corn starch, with high SSC signal had high intensities at 1045 and 1022 cm^-1. Hence, our data demonstrate that the structural complexity detected by the SSC signal is mainly associated with lamellar and crystalline features of starch granules.

Single-step ethanol production from raw cassava starch using a combination of raw starch hydrolysis and fermentation, scale-up from 5-L laboratory and 200-L pilot plant to 3000-L industrial fermenters

BACKGROUND

A single-step ethanol production is the combination of raw cassava starch hydrolysis and fermentation. For the development of raw starch consolidated bioprocessing technologies, this research was to investigate the optimum conditions and technical procedures for the production of ethanol from raw cassava starch in a single step. It successfully resulted in high yields and productivities of all the experiments from the laboratory, the pilot, through the industrial scales. Yields of ethanol concentration are comparable with those in the commercial industries that use molasses and hydrolyzed starch as the raw materials.

RESULTS

Before single-step ethanol production, studies of raw cassava starch hydrolysis by a granular starch hydrolyzing enzyme, StargenTM002, were carefully conducted. It successfully converted 80.19% (w/v) of raw cassava starch to glucose at a concentration of 176.41 g/L with a productivity at 2.45 g/L/h when it was pretreated at 60 °C for 1 h with 0.10% (v/w dry starch basis) of Distillase ASP before hydrolysis. The single-step ethanol production at 34 °C in a 5-L fermenter showed that Saccharomyces cerevisiae (Fali, active dry yeast) produced the maximum ethanol concentration, pmax at 81.86 g/L (10.37% v/v) with a yield coefficient, Yp/s of 0.43 g/g, a productivity or production rate, rp at 1.14 g/L/h and an efficiency, Ef of 75.29%. Scale-up experiments of the single-step ethanol production using this method, from the 5-L fermenter to the 200-L fermenter and further to the 3000-L industrial fermenter were successfully achieved with essentially good results. The values of pmax, Yp/s, rp, and Ef of the 200-L scale were at 80.85 g/L (10.25% v/v), 0.42 g/g, 1.12 g/L/h and 74.40%, respectively, and those of the 3000-L scale were at 70.74 g/L (8.97% v/v), 0.38 g/g, 0.98 g/L/h and 67.56%, respectively. Because of using raw starch, major by-products, i.e., glycerol, lactic acid, and acetic acid of all three scales were very low, in ranges of 0.940-1.140, 0.046-0.052, 0.000-0.059 (% w/v), respectively, where are less than those values in the industries.

CONCLUSION

The single-step ethanol production using the combination of raw cassava starch hydrolysis and fermentation of three fermentation scales in this study is practicable and feasible for the scale-up of industrial production of ethanol from raw starch.

Overexpression of an endogenous raw starch digesting mesophilic α-amylase gene in Bacillus amyloliquefaciens Z3 by in vitro methylation protocol

BACKGROUND

Mesophilic α-amylases function effectively at low temperatures with high rates of catalysis and require less energy for starch hydrolysis. Bacillus amyloliquefaciens is an essential producer of mesophilic α-amylases. However, because of the existence of the restriction-modification system, introducing exogenous DNAs into wild-type B. amyloliquefaciens is especially tricky.

RESULTS

α-Amylase producer B. amyloliquefaciens strain Z3 was screened and used as host for endogenous α-amylase gene expression. In vitro methylation was performed in recombinant plasmid pWB980-amyZ3. With the in vitro methylation, the transformation efficiency was increased to 0.96 × 10² colony-forming units μg^-1 plasmid DNA. A positive transformant BAZ3-16 with the highest α-amylase secreting capacity was chosen for further experiments. The α-amylase activity of strain BAZ3-16 reached 288.70 ± 16.15 U mL^-1 in the flask and 386.03 ± 16.25 U mL^-1 in the 5-L stirred-tank fermenter, respectively. The Bacillus amyloliquefaciens Z3 expression system shows excellent genetic stability and high-level extracellular production of the target protein. Moreover, the synergistic interaction of AmyZ3 with amyloglucosidase was determined during the hydrolysis of raw starch. The hydrolysis degree reached 92.34 ± 3.41% for 100 g L^-1 raw corn starch and 81.30 ± 2.92% for 100 g L^-1 raw cassava starch after 24 h, respectively.

CONCLUSION

Methylation of the plasmid DNA removes a substantial barrier for transformation of B. amyloliquefaciens strain Z3. Furthermore, the exceptional ability to hydrolyze starch makes α-amylase AmyZ3 and strain BAZ3-16 valuable in the starch industry. © 2020 Society of Chemical Industry.

Simultaneous saccharification and fermentation of native rye, wheat and triticale starch

BACKGROUND

The increasing global demand for starchy raw material requires new methods for obtaining ethanol from a range of plants using environmentally friendly methods. Granular starch-hydrolyzing enzymes (GSHE) can effectively support the development of the distillery industry.

RESULTS

The aim of this study was to evaluate the effectiveness of simultaneous saccharification and fermentation of native rye, wheat or triticale starch. Mashes were prepared using methods that limit water and energy consumption (pre-hydrolysis at 35 °C for 30 min). The results show that the degree of starch saccharification depended on the raw material. However, the highest yields of ethanol were obtained with 100 kg of triticale mashes (38.9 ± 1.4 L absolute alcohol) as compared to rye and wheat mashes. The concentration of dry matter (between 250 and 280 g L^-1 ) in the mashes was not associated with a decrease in ethanol yield and improved efficiency in the case of wheat and triticale.

CONCLUSION

Simultaneous saccharification and fermentation offers a low-cost and environmentally friendly alternative to existing procedures for industrial ethanol production, which may be of particular interest to raw-spirit producers, as well as to the food and fermentation industry at large. © 2019 Society of Chemical Industry.

Variance of Zein Protein and Starch Granule Morphology between Corn and Steam Flaked Products Determined Starch Ruminal Degradability Through Altering Starch Hydrolyzing Bacteria Attachment

The current study investigated differences of γ-zein protein contents and starch granule characteristics between raw and steam flaked corns and their influences on ruminal starch hydrolyzing bacteria (SHB) attached to corn grain. Two types of raw (Corn1 and Corn2) and their steam-flaked products (SFCorn1 and SFCorn2) were applied to explore physiochemical structures and SHB attachment. SDS-PAGE was conducted to detect γ-zein protein patterns, scanning electron microscope, and small angle X-ray scattering were performed to obtain starch granule morphology, while crystallinity, DQ starch, and DAPI staining were applied to quantify SHB. The steam flaking process destroyed γ-zein proteins and gelatinized starch granules. The median particle size of Corn1 and Corn2 starch granules increased from 17.8 and 18.0 μm to 30.8 and 26.0 μm, but crystallinity decreased from 22.0 and 25.0% to 9.9 and 16.9%, respectively. The percentage of SHB attached to Corn1 residues decreased (p = 0.01) after 4 h incubation, but SHB attached to SFCorn1 residues increased (p = 0.03) after 12 h incubation. Thus, the differences of γ-zein proteins and starch granule physiochemical structures between raw and steam flaked corn played an important role in improving the rate and extent of starch ruminal degradation through altering the process of SHB attached to corn.

Cold hydrolysis of cassava pulp and its use in simultaneous saccharification and fermentation (SSF) process for ethanol fermentation

The present study investigated cold hydrolysis of cassava pulp (CP) and the use of cold hydrolysis with simultaneous saccharification and fermentation (SSF) for ethanol production. Cold hydrolysis of 100 g-CP/L at 50 °C for 2 h, followed by at 30 °C for 72 h resulted in the production of 71.5 ± 1.8 g/L of reducing sugar, with a yield of 0.72 g/g-CP. A mathematical model describing the cold hydrolysis process was subsequently developed. The model proved to be applicable for other cold hydrolysis systems with satisfactory results. The sequential process of cold hydrolysis at 50 °C for 2 h, followed by SSF at 30 °C for 72 h gave 27.4 g-ethanol/L, with a productivity of 0.37 g/(L h) and a fermentation efficiency of 57.58%. Based on the results, a bioconversion process for CP to ethanol was proposed. In this process, 1 kg of ethanol could be produced from 3.65 kg of CP without any nutrient supplementation.

Reduction of falling number in soft white spring wheat caused by an increased proportion of spherical B-type starch granules

A low falling number (FN) in wheat indicates high α-amylase activity associated with poor end-use quality. We hypothesize starch - the substrate of α-amylase, can directly influence hot flour pasting properties and its susceptibility to α-amylase, which further affects viscosity. We examined the structural characteristics of starch in three soft white spring wheat cultivars grown in Idaho in 2013 (normal FN year) and 2014 (low FN year with pre-harvest rains). Our data surprisingly show that starch in some low FN wheat was not significantly degraded by α-amylase but had developmental changes with an increased proportion of B-type wheat starch. We reconstituted wheat starch and verified that starch with an increase of B-granules has a relatively low viscosity and high susceptibility to wheat α-amylase, which further facilitates the decrease of viscosity. The influence of starch structure and starch-enzyme interaction must be considered while developing a solution to the low FN issue.

Comparison of Physicochemical Properties of Starches from Nine Chinese Chestnut Varieties

Chestnut is a popular food in many countries and is also an important starch source. In previous studies, physicochemical properties of starches have been compared among different Chinese chestnut varieties growing under different conditions. In this study, nine Chinese chestnut varieties from the same farm were investigated for starch physicochemical properties to exclude the effects of growing conditions. The dry kernels had starch contents from 42.7 to 49.3%. Starches from different varieties had similar morphologies and exhibited round, oval, ellipsoidal, and polygonal shapes with a central hilum and smooth surface. Starch had bimodal size distribution and the volume-weighted mean diameter ranged from 7.2 to 8.2 μm among nine varieties. The starches had apparent amylose contents from 23.8 to 27.3% but exhibited the same C-type crystalline structure and similar relative crystallinity, ordered degree, and lamellar structure. The gelatinization onset, peak, and conclusion temperatures ranged from 60.4 to 63.9 °C, from 64.8 to 68.3 °C, and from 70.5 to 74.5 °C, respectively, among nine starches; and the peak, hot, breakdown, final, and setback viscosities ranged from 5524 to 6505 mPa s, from 3042 to 3616 mPa s, from 2205 to 2954 mPa s, from 4378 to 4942 mPa s, and from 1326 to 1788 mPa s, respectively. The rapidly digestible starch, slowly digestible starch, and resistant starch ranged from 2.6 to 3.7%, from 5.7 to 12.7%, and from 84.4 to 90.7%, respectively, for native starch, and from 79.6 to 89.5%, from 1.3 to 3.8%, and from 7.1 to 17.4%, respectively, for gelatinized starch.

A simple and rapid method for preparing the whole section of starchy seed to investigate the morphology and distribution of starch in different regions of seed

BACKGROUND

Storage starch in starchy seed influences the seed weight and texture, and determines its applications in food and nonfood industries. Starch granules from different plant sources have significantly different shapes and sizes, and even more the difference exists in the different regions of the same tissue. Therefore, it is very important to in situ investigate the morphology and distribution of starch in the whole seed. However, a simple and rapid method is deficient to prepare the whole section of starchy seed for investigating the morphology and distribution of starch in the whole seeds for a large number of samples.

RESULTS

A simple and rapid method was established to prepare the whole section of starchy seed, especially for floury seed, in this study. The whole seeds of translucent and chalky rice, vitreous and floury maize, and normal barley and wheat were sectioned successfully using the newly established method. The iodine-stained section clearly exhibited the shapes and size of starch granules in different regions of seed. The starch granules with different morphologies and iodine-staining colors existed regionally in the seeds of high-amylose rice and maize. The sections of lotus and kidney bean seeds also showed the feasibility of this method for starchy non-cereal seeds.

CONCLUSION

The simple and rapid method was proven effective for preparing the whole sections of starchy seeds. The whole section of seed could be used to investigate the morphology and distribution of starch granules in different regions of the whole seed. The method was especially suitable for large sample numbers to investigate the starch morphology in short time.

Interspecific and intergeneric hybridization as a source of variation for wheat grain quality improvement

The hybridization events with wild relatives and old varieties are an alternative source for enlarging the wheat quality variability. This review describes these process and their effects on the technological and nutritional quality. Wheat quality and its end-uses are mainly based on variation in three traits: grain hardness, gluten quality and starch. In recent times, the importance of nutritional quality and health-related aspects has increased the range of these traits with the inclusion of other grain components such as vitamins, fibre and micronutrients. One option to enlarge the genetic variability in wheat for all these components has been the use of wild relatives, together with underutilised or neglected wheat varieties or species. In the current review, we summarise the role of each grain component in relation to grain quality, their variation in modern wheat and the alternative sources in which wheat breeders have found novel variation.

Mechanical and barrier properties of maize starch-gelatin composite films: effects of amylose content

BACKGROUND

In order to obtain new reinforcing bio-fillers to improve the physicochemical properties of gelatin-based films, three types of maize starch, waxy maize starch (Ap), normal starch (Ns) and high-amylose starch (Al), were incorporated into gelatin film and the resulting film properties were investigated, focusing on the impact of amylose content.

RESULTS

The thickness, opacity and roughness of gelatin film increased depending on the amylose content along with the starch concentration. The effects of the three starches on the mechanical properties of gelatin film were governed by amylose content, starch concentration as well as environmental relative humidity (RH). At 75% RH, the presence of Al and Ns in the gelatin matrix increased the film strength but decreased its elongation, while Ap exhibited an inverse effect. Starch addition decreased the oxygen permeability of the film, with the lowest value at 20% Al and Ns. All starches, notably at 30% content, led to a decrease in the water vapor permeability of the film at 90% RH, especially Ns starch. Furthermore, the starches improved the thermal stability of the film to some extent. Fourier transform infrared spectra indicated that some weak intermolecular interactions such as hydrogen bonding occurred between gelatin and starch. Moreover, a high degree of B-type crystallinity of starch was characterized in Gel-Al film by X-ray diffraction.

CONCLUSION

Tailoring the properties of gelatin film by the incorporation of different types of maize starch provides the potential to extend its applications in edible food packaging. © 2017 Society of Chemical Industry.

Progress in High-Amylose Cereal Crops through Inactivation of Starch Branching Enzymes

High-amylose cereal starches provide many health benefits for humans. The inhibition or mutation of starch branching enzyme (SBE) genes is an effective method to develop high-amylose cereal crops. This review summarizes the development of high-amylose cereal crops through the inactivation of one or more SBE isoforms or combination with other genes. This review also reveals the causes of increase in amylose content in high-amylose crops. A series of changes, including amylopectin structure, crystalline structure, thermal properties, and hydrolysis properties, occurs as amylose content increases. The different morphological starch granules nominated as heterogeneous starch granules or differently stained starch granules are detected in high-amylose cereal crops. Detailed studies on four heterogeneous starch granules in high-amylose rice, which is developed by antisense RNA inhibition of SBEI/IIb, indicate that granules with different morphologies possess various molecular structures and physicochemical and functional properties. This variation diversifies their applications in food and non-food industries. However, current knowledge regarding how these heterogeneous starch granules form and why they exhibit regional distribution in endosperm remain largely unknown.

Mechanisms of starch digestion by α-amylase-Structural basis for kinetic properties

Recent studies of the mechanisms determining the rate and extent of starch digestion by α-amylase are reviewed in the light of current widely-used classifications for (a) the proportions of rapidly-digestible (RDS), slowly-digestible (SDS), and resistant starch (RS) based on in vitro digestibility, and (b) the types of resistant starch (RS 1,2,3,4…) based on physical and/or chemical form. Based on methodological advances and new mechanistic insights, it is proposed that both classification systems should be modified. Kinetic analysis of digestion profiles provides a robust set of parameters that should replace the classification of starch as a combination of RDS, SDS, and RS from a single enzyme digestion experiment. This should involve determination of the minimum number of kinetic processes needed to describe the full digestion profile, together with the proportion of starch involved in each process, and the kinetic properties of each process. The current classification of resistant starch types as RS1,2,3,4 should be replaced by one which recognizes the essential kinetic nature of RS (enzyme digestion rate vs. small intestinal passage rate), and that there are two fundamental origins for resistance based on (i) rate-determining access/binding of enzyme to substrate and (ii) rate-determining conversion of substrate to product once bound.