Characterization of the baking-induced changes in starch molecular and crystalline structures in sugar-snap cookies

Effects of Wx, SSIIa and FLO2 alleles and their interactions on the formation of multi-scale structures of rice starch

The multi-scale structures of rice starches from 16 recombinant inbred lines and their parents with different combinations of Wx, SSIIa and FLO2 alleles were investigated. Results indicated that the starch multi-scale structures were significantly affected by genotype, environment and genotype × environment interaction. Wx, SSIIa and FLO2 alleles and their interactions significantly affected the starch fine structure. Starches with Wxa allele had higher amylose content (AC) in different amylose chain regions (hAm,i∼iii), degree of polymerization (DP) of amylose peak (XAm), Bragg long period distance (dac), but lower relative crystallinity (RC) compared with Wxb. The starches with SSIIaGC allele had higher XAm, more amylopectin B1 chains (fb1) and RC, but less A chains (fa) and dac than those of SSIIaTT. The floury2 (flo2) mutant starch displayed increased ratio of the peak heights of amylopectin (hAP2/hAP1), fb2 and dac, but decreased RC compared to the wildtype. The Wx × SSIIa interaction had a significant impact on AC, XAP1, βAm,iii, average chain length of amylopectin molecules (X¯) and RC. The interaction effects of FLO2 × Wx were significant for AC, hAm/hAp1, hAm,ii, βAm,iii, hAm,iii, RC, D and dac. Significant FLO2 × SSIIa interaction was detected for XAM, hAP2/hAP1, βAm,ii, fb1, fb3 and RC. FLO2 × Wx×SSIIa effect was significant for XAP1, hAP2/hAP1, βAm,ii, fa, fb3 and X¯. This study provides insights into the individual and interactive effects of the Wx, SSIIa and FLO2 alleles, as well as environmental factors, on the starch fine structure. These results may promote high-quality rice breeding through structural modifications of starch.

Physicochemical and sensory properties of reduced-fat cookies made from gluten-free flour incorporated with glucomannan

BACKGROUND

The food industry faces an important challenge in the reformulation of food products to reduce fat at the same time as retaining crucial properties, such as acceptable appearance, texture and mouthfeel. In the present study, a fat replacer from glucomannan was incorporated in cookies prepared from fermented cassava flour (FCF) and soy protein concentrate (SPC), and its effect on physicochemical and sensory properties was analyzed. The samples included cookies made from FCF and SPC with fat substitution levels of 0% (CS100: FCF-SPC, 100% fat), 20% (GM80: FCF-SPC-medium glucomannan, 80% fat) and 30% (GH70: FCF-SPC-high glucomannan, 70% fat). Fat replacement in GM80 and GH70 cookies was achieved through incorporation of glucomannan and water. The cookie made from wheat flour was selected as the gold standard.

RESULTS

Cookies with fat replacement levels of 20% (GM80) and 30% (GH70) had lower fat and higher dietary fiber content than the control samples. The addition of glucomannan improved the spread ratio of GM80 and GH70 cookies. No significant difference was observed between the sensory acceptance of GH70 and CS100 cookies in terms of aroma, texture, taste and overall acceptability (P > 0.05). In addition, no significant difference was detected in the fat taste intensity among GH70, GM80 and CS100 cookies.

CONCLUSION

The results of the present study indicate that glucomannan can be used to replace fat in cookies prepared from FCF and SPC. Glucomannan enhanced the nutritional properties of cookies. Fat replacement by glucomannan maintained the product's physical properties, sensory acceptance and fat mouthfeel. © 2024 Society of Chemical Industry.

The molecular structure of leaf starch from three cereal crops

Plants produce storage and transient starches in seeds and in leaves, respectively. Understanding molecular fine structure and synthesis of transient starch can help improve plant quality (e.g. by helping breeders produce slowly digested amylopectin, which is beneficial for human nutrition). In the present study, leaf starches from rice, wheat and barley were isolated with cesium chloride gradient centrifugation. Starch fine structure was measured using size-exclusion chromatography and flurophore-assisted carbohydrate electrophoresis. The chain-length distribution (CLD) of amylopectin leaf starch was trimodal in wheat and barley leaf starch. The global peak of leaf starch was at degree of polymerization (DP) 22, and leaf amylopectin containeds more long branches, which are generally considered to hinder starch digestion, suggesting that leaf-specific starch synthesis enzymes could be expressed in the endosperm by genetic modification to produce amylopectin with more long chains, which would be more slowly digested, with advantages to human health. HYPOTHESIS: The biosynthetic processes for leaf starch and storage starch in a given plant species will show significant differences.

Oil-in-water emulsion activity and stability of short-term retrograded starches depend on starch molecular size, amylose content, and amylopectin chain length

BACKGROUND

Natural emulsifiers are increasingly preferred by the food industry to meet consumers' demand for 'clean-label' emulsion products. In the present study, 10 short-term retrograded starches with unique molecular structures were explored to examine the relationships between starch structures and their ability to form stable oil-in-water emulsions.

RESULTS

Waxy maize starch showed the largest value of contact angle and conductivity of emulsion, whereas potato and lentil starch showed the lowest value of contact angle and conductivity of emulsion, respectively. Emulsion prepared by rice starch showed the lowest, whereas that of sweet potato starch showed the highest value of viscosity. Consequentially, the emulsion stabilized with waxy maize and tapioca starch showed the smallest and less polydisperse droplets, resulting in a much higher emulsifying index. On the other hand, emulsion prepared with potato starch showed the highest stability compared to other starches. Correlation analysis suggested that starches with larger molecular size, a lower amylose content and shorter amylopectin short chains had a higher emulsification ability, whereas the amount of starch molecular interactions formed during short-term retrogradation revealed no obvious linking to emulsion performances.

CONCLUSION

These findings provided food industry with exciting opportunities to develop 'clean-label' emulsions with desirable properties. © 2024 Society of Chemical Industry.

Thermally processed rice starch impacts glucose homeostasis in mice to different degrees via disturbing gut microbial structure and intestinal barrier function

Long-term intake of thermally processed starch-based foods may impact glucose homeostasis, but the consistency of the effects of various thermal treatments and the reasons are not clear. In this study, thermal treatments, especially boiling, damaged the crystal structure and inter-molecular hydrogen bonds of starch-based blends, thus decreasing the structural order and stability. These thermally treated starch-based blends increased the appetite of mice, promoted food digestion, and enhanced postprandial glucose response. Normal C57BL/6J mice were treated with boiled, baked, and fried starch-based diets for ten weeks. Compared to the baked and fried starch-based diets, the boiled starch-based diet significantly (p < 0.05) elevated random blood glucose levels and disrupted insulin homeostasis, primarily due to the remarkable decrease in gut microbial diversity. Both baked and fried starch-based diets resulted in relatively high intestinal epithelial permeability (plasma lipopolysaccharide increased by 28.67 % and 21.85 %, respectively). They adversely affected islet β-cell function and evoked glucose metabolism disorder. Overall, results demonstrate a clear connection among the thermal processing of starch-based diets, disruption of intestinal homeostasis, and adverse glucose metabolism. This study lays a theoretical foundation for the formulation of food processing strategies to mitigate the adverse effects of thermally treated food on glucose homeostasis.

Upcycling of Non-Standard Cakes by Manufacturing Ring-Shaped Cookies

A creative approach to reducing food waste by reusing industrial cake waste can result in the development of a worldwide favorite snack. This study aimed to evaluate the potential of industrial cake wastes-basic mini cake (BMC), filled mini cake (FMC), and traditional mini cake (TMC)-as sustainable alternatives to wheat flour in producing ring-shaped cookies. After initial screening, FMC was upcycled at 10%, 15%, 20%, 30%, and 50% of wheat flour replacement for ring-shaped cookie processing. Only the formulations containing 10, 15, and 20% FMC waste showed good moldability and similar rheological parameters between each other (p < 0.05). After baking, the cookies made with FMC waste showed greater volume expansion (p < 0.05) compared to the standard formulation. All cookies had water activity below 0.6 and remained stable during the 150 days of storage. Furthermore, after 150 days of storage, the hardness of the standard (T1) formulation was 40.02 N, while formulations with FMC waste (10%-T2, 15%-T3, and 20%-T4) resulted in softer cookies, with hardness values of 26.9 N, 27.9 N, and 27.61 N, respectively. The ring-shaped cookies containing 15% FMC waste showed the best technological performance, considering manufacture, physicochemical, and hardness traits, with no nutritional differences compared to the control.

Unlocking the potential of rice bran oil body as fat replacement in cookies: single and double crosslinked binary emulsion-filled gels based on lutein-loaded rice bran oil body emulsion

BACKGROUND

Rice bran oil body is rich in nutritional value, which is a byproduct of rice processing. The aim of this study is to develop a novel emulsion-filled gel with lutein-loaded rice bran oil body and investigate its functionality as a fat replacer in cookies. The effects of incorporating structured oil body in the form of emulsion-filled gel instead of butter in cookies with a ratio of 0, 10, 20 and 50 wt% formulation were determined by measuring appearance, texture, thermodynamic properties, moisture distribution and microstructure.

RESULTS

The results demonstrated the relationship between geometry, moisture and structure. The 20 wt% emulsion-filled gel substitution ratio yielded mobility and distribution abilities of melted fat and sugar in the cookies that were closest to those of butter. The addition of emulsion-filled gel increased the L* value and decreased the a* value, while the b* value of the cookie increased due to the advanced delivery of lutein by oil body. By controlling the addition ratio, the texture of the cookies can be adjusted. Starch granules were separated due to colloidal particles, reducing saturated fat content and decreasing cookie gelatinization enthalpy. The fat coating on starch particles enhanced the binding capacity of free water, improving air entrapment and forming a constrained gluten network structure.

CONCLUSION

These findings provide a theoretical basis for rice bran oil body as a novel substitute for butter in the development of healthy, high-quality cookies. © 2024 Society of Chemical Industry.

Insight to starch retrogradation through fine structure models: A review

The retrogradation of starch is crucial for the texture and nutritional value of starchy foods products. There is mounting evidence highlighting the significant impact of starch's fine structures on starch retrogradation. Because of the complexity of starch fine structure, it is a formidable challenge to study the structure-property relationship of starch retrogradation. Several models have been proposed over the years to facilitate understanding of starch structure. In this review, from the perspective of starch models, the intricate structure-property relationship is sorted into the correlation between different types of structural parameters and starch retrogradation performance. Amylopectin B chains with DP 24-36 and DP ≥36 exhibit a higher tendency to form ordered crystalline structures, which promotes starch retrogradation. The chains with DP 6-12 mainly inhibit starch retrogradation. Based on the building block backbone model, a longer inter-block chain length (IB-CL) enhances the realignment and reordering of starch. The mathematical parameterization model reveals a positive correlation between amylopectin medium chains, amylose short chains, and amylose long chains with starch retrogradation. The review is structured according to starch models; this contributes to a clear and comprehensive elucidation of the structure-property relationship, thereby providing valuable references for the selection and utilization of starch.

Exploration of unique starch physicochemical properties of novel buckwheat lines created by crossing Golden buckwheat and Tatary buckwheat

Buckwheat is considered as a healthy cereal food, and it is essential to cultivate new buckwheat lines with good starch physicochemical properties for both consumers and food producers. Six novel buckwheat (Duoku, Dk) were generated by crossing of Golden buckwheat and Tatary buckwheat, and their kernel appearance properties and starch physicochemical properties were analyzed together with one domestic line (Cimiqiao) and one wild line (Yeku). The results showed that Dk samples had better appearance properties than two control samples. The Dk samples showed lower amylose content, similar amylopectin molecular structure and chain length distributions, and larger starch granules compared with Cimiqiao. The digestion results showed that two Dk samples: Dk6 & Dk9 had high resistant starch content; while the other two Dk samples: Dk37 & Dk38 had a steady glucose releasing rate. The Dk samples also showed high gelatinization temperature, indicating they were good raw materials for producing glass noodle. This study proved that Dk buckwheat had unique starch physicochemical properties, and could be used as new food materials in the future.

Formation, Structural Characterization, and Functional Properties of Corn Starch/Zeaxanthin Composites

Zeaxanthin is a natural xanthophyll carotenoid and the main macular pigment that protects the macula from light-initiated oxidative damage, but it has poor stability and low bioavailability. Absorption of this active ingredient into starch granules as a carrier can be used to improve both zeaxanthin stability and controlled release. Optimization using three variables judged important for optimizing the system (reaction temperature of 65 °C, starch concentration of 6%, and reaction time of 2 h) was conducted for incorporation of zeaxanthin into corn starch granules, aiming for high zeaxanthin content (2.47 mg/g) and high encapsulation efficiency (74%). Polarized-light microscopy, X-ray diffraction, differential scanning calorimetry, and Fourier transform infrared spectroscopy showed that the process partially gelatinized corn starch; additionally, it showed the presence of corn starch/zeaxanthin composites, with the zeaxanthin successfully trapped in corn starch granules. The half-life time of zeaxanthin in corn starch/zeaxanthin composites increased to 43 days as compared with that of zeaxanthin alone (13 days). The composites show a rapid increase in zeaxanthin release with in vitro intestinal digestion, which is favorable for possible use in living systems. These findings could have application in designing effective starch-based carriers of this bioactive ingredient with enhanced storage stability and improved intestines-targeted controlled-release delivery.

Identification of a new allele of soluble starch synthase IIIa involved in the elongation of amylopectin long chains in a chalky rice mutant

A chalky endosperm mutant (GM03) induced from an indica rice GLA4 was used to investigate the functional gene in starch biosynthesis. Bulked segregant analysis and sanger sequencing determined that a novel mutation in soluble starch synthase IIIa (SSIIIa) is responsible for the chalky phenotype in GM03. Complementary test by transforming the active SSIIIa gene driven by its native promoter to GM03 recovered the phenotype to its wildtype. The expression of SSIIIa was significantly decreased, while SSIIIa protein was not detected in GM03. The mutation of SSIIIa led to increased expression of most of starch synthesis related genes and elevated the levels of most of proteins in GM03. The CRISPR/Cas9 technology was used for targeted disruption of SSIIIa, and the mutant lines exhibited chalky endosperm which phenocopied the GM03. Additionally, the starch fine structure in the knockout mutant lines ss3a-1 and ss3a-2 was similar with the GM03, which showed increased amylose content, higher proportions of B1 and B2 chains, much lower proportions of B3 chains and decreased degree of crystallinity, leading to altered thermal properties with lower gelatinization temperature and enthalpy. Collectively, these results suggested that SSIIIa plays an important role in starch synthesis by elongating amylopectin long chains in rice.

Combined Effects of BEIIb and SSIIa Alleles on Amylose Contents, Starch Fine Structures and Physicochemical Properties of Indica Rice

Starch branching enzyme IIb (BEIIb) and soluble starch synthase IIa (SSIIa) play important roles in starch biosynthesis in cereals. Deficiency in the BEIIb gene produces the amylose extender (ae) mutant rice strain with increased amylose content (AC) and changes in the amylopectin structure. The SSIIa gene is responsible for the genetic control of gelatinization temperature (GT). The combined effects of BEIIb and SSIIa alleles on the AC, fine structures, and physicochemical properties of starches from 12 rice accessions including 10 recombinant inbred lines (RIL) and their two parents were examined in this study. Under the active BEIIb background, starches with the SSIIa-GC allele showed a higher GT than those with the SSIIa-TT allele, resulting from a lower proportion of A chain and a larger proportion of B1 chains in the amylopectin of SSIIa-GC. However, starch with the BEIIb mutant allele (be2b) in combination with any SSIIa genotype displayed more amylose long chains, higher amylose content, B2 and B3 chains, and molecular order, but smaller relative crystallinity and proportion of amylopectin A and B1 chains than those with BEIIb, leading to a higher GT and lower paste viscosities. These results suggest that BEIIb is more important in determining the structural and physicochemical properties than SSIIa. These results provide additional insights into the structure-function relationship in indica rice rather than that in japonica rice and are useful for breeding rice with high amylose content and high resistant starch.

Oligosaccharides elevate the gelatinization temperature of wheat starch more than sucrose, paving the way for their use in reduced sugar starch-based formulations

The gelatinization of wheat starch influences the final structure and texture of baked goods. Sucrose effectively elevates the gelatinization temperature (T_gel) of starch more than many sweeteners, and maintaining a higher T_gel has been a challenge while reducing the amount of sucrose in baked goods. The objective of this study was to quantify the effects of 14 different oligosaccharides (OS: maltose, isomaltulose, kestose, maltotriose, melezitose, raffinose, stachyose, a fructo-OS, a galacto-OS, an isomalto-OS, lactosucrose, a xylo-OS, and two glucose-based dextrins), allulose, and sucrose at different concentrations (0 to 60% w/w) on the T_gel of wheat starch using DSC, and to determine which OS physicochemical properties best explained the T_gel results. OS type and concentration significantly altered T_gel. Many OS elevated the T_gel as much as or more than sucrose at the same solution concentrations, while allulose did not. The onset T_gel in water was 60 °C, in 60% sucrose was 96 °C, in 60% allulose was 80 °C, and T_gel increased up to 107-108 °C in 60% fructo-OS and Nutriose® solutions. The effects of OS on T_gel correlated most strongly (r > 0.95) with two OS solution parameters: the solvent effective volume fraction (ϕ_w,eff, related to solute intermolecular hydrogen bond density) and solution viscosity, to a lesser extent with solution water activity, and not to the glass transition temperature of the OS. Based on T_gel elevation, many of the OS are promising sucrose replacements in baked goods, which could facilitate their use in desirable higher fiber, reduced sugar starch-based baked product formulations.

Effects of single and dual modifications through electron beam irradiation and hydroxypropylation on physicochemical properties of potato and corn starches

In this study, electron beam irradiation (EBI; 2, 4, 6, 8 and 10 kGy), hydroxypropylation (HP) and dual modification of EBI-HP were applied to modify corn and potato starches. The results showed that the molar substitution (MS) of EBI-HP modified corn and potato starches were in the range of 0.060-0.087 and 0.080-0.124, respectively. After modifications, amylose content of corn (30.0 %) and potato (31.2 %) starches were declined to 24.2-28.1 % and 26.1-29.5 %, respectively, and relative crystallinity was reduced from 35.5 to 30.0 % for corn and 34.1 to 20.2 % for potato. Pasting properties decreased significantly in both starch sources with increasing irradiation dose. EBI decreased springiness, enthalpy of retrograded starch (ΔHr) and percentage of retrogradation (R%) on corn starches, which were different from those effects observed on potato starches. Meanwhile, HP increased peak viscosity up to 312.6 RVU and 1359.3 RVU for corn and potato starches, respectively. Moreover, EBI-HP was highly responsible for the decreases in the textural, gelatinization and retrogradation properties and relative crystallinity in both corn and potato starches. These results enhance the understanding of starch functionality modified by using both physical and chemical methods, and provide further insights on food and non-food applications.

Relative importance of branching enzyme isoforms in determining starch fine structure and physicochemical properties of indica rice

Down-regulation of starch branching enzymes alters fine structure and starch properties, especially the B-type crystalline pattern and extremely high amylose content identified in the BEIIb-deficiency mutant in the indica rice. The relative importance of the starch branching enzymes in determining the molecular fine structure and starch functional properties were uncovered in this study. An indica rice, Guangluai 4 with high amylose content (AC) and high gelatinization temperature (GT) was used to generate the clustered regularly interspaced short palindromic repeats (CRISPR)/associated protein-9 (Cas9) knockout lines. Five mutant lines were identified including be1-1, be1-2, be2a-1, be2a-2 and be2b-1, and analysis of western blot showed the CRISPR/Cas9 system was successful in inducing mutations in the targeted genes. AC of be2b-1 (34.1%) was greater than that of wild type (WT) (27.4%) and other mutants. Mutations of either BEI or BEIIa did not alter the starch crystallite pattern (A-type). The BEIIb deficiency caused an opaque endosperm phenotype, changed the crystallite pattern from A- to B-type, and dramatically increased the degree of ordered structure, the relative proportion of amylose chains and intermediate to long amylopectin chains, average chain length of amylopectin molecules as well as GT. The BEIIa deficiency had no effect on the proportion of amylose chains, the length of amylopectin intermediate-long chains, conclusion temperature and enthalpy of gelatinization. Down-regulation of BEI increased the proportion of shortest amylopectin chains (fa) but decreased the proportion of long amylopectin chains (fb2 and fb3), leading to a lower GT. It is concluded that the relative importance in determining starch fine structures and functionality was in the order of BEIIb > BEI > BEIIa. Our results provide new information for utilizations of BE-deficient mutants in rice quality breeding.

The role of different Wx and BEIIb allele combinations on fine structures and functional properties of indica rice starches

This study examined the effects of the combinations of Waxy (Wx) and starch branching enzyme IIb (BEIIb) alleles on starch fine structure and functional properties in indica rice cultivars. The results showed that be2b mutant starches with BEIIb deficiency had higher amylose content, shorter amylose long chains, a higher proportion of amylopectin long chains and molecular order, but a lower proportion of amylopectin short chains and relative crystallinity, resulting in higher gelatinization temperature but lower enthalpy and paste viscosity. Compared with the rice lines carrying Wx^b allele, Wx^a allele contributed to relatively higher amylose content, longer amylopectin chains, less short-range ordered structure and lower relative crystallinity, leading to a little lower gelatinization enthalpy. This study provides new insight into structure-function relations among rice lines with different allele combinations of starch synthesis related genes, which is a useful strategy for rice quality breeding.

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.

Relations between rice starch fine molecular and lamellar/crystalline structures

Starch lamellar and crystalline structures are important controller of its physicochemical and digestion properties. Here, starch lamellar/crystalline structures of 16 different rice starches were investigated and correlated with their chain-length distributions (CLDs) and molecular size distributions. Results showed that the thickness of amorphous lamellae was mainly correlated with the amount of amylose short and medium chains. Thickness of both amorphous and crystalline lamellae was negatively correlated with the amount of amylopectin medium chains and relative length of amylopectin short chains. The degree of crystallinity was negatively correlated with the amount of amylose short and long chains. The lamellar ordering, fractal nature and thickness polydispersity were also related to the starch CLDs. Whereas, starch molecular size distributions were shown to be lack of correlations with the starch lamellar/crystalline structures. This study helps a better understanding of the molecular nature of starch semi-crystalline lamellae.