Influence of amylose on the pasting and gel texture properties of chestnut starch during thermal processing

Importance of starch chain-length distribution in determining starch digestibility through affecting short- and long-range intermolecular interactions during retrogradation

Starch retrogradation involves both short- and long-range intermolecular interactions, while their relations with starch chain-length distribution (CLD) and digestibility are less clear. To address this, 9 types of starches with distinct CLDs were analyzed for intermolecular interactions and digestibility over 7 days of retrogradation. Wheat starch exhibited a higher ratio of long-range intermolecular interactions, while pea, mung bean, potato, sweet potato, lentil, and corn starch formed more short-range intermolecular interactions. All retrograded starches displayed B + V crystallinity with characteristic peaks at 17°, 20°, and 22°. The pores of some starch hydrogels shrank after retrogradation. Most importantly, positive correlations were for the first time observed between amylose chains of 100 < DP ≤ 5000 and intermolecular interactions. Whereas a higher level of the intermolecular interactions was negatively correlated with enzymatic binding rate constants (the rate-limiting step of digestion) and maximum digested percentages. In conclusion, these results suggest that starches with more amylose chains with 100 < DP ≤ 5000 are preferable in terms of promoting a slow starch digestibility.

A novel isolation technique for sweetpotato starch and its application in thermal property characterization

BACKGROUND

The utilization of sweetpotato starch in the food industry is significantly influenced by the granule size of the starch. To isolate sweetpotato starch fractions with different sizes, an efficient isolation method is in demand. The differences in thermal properties of starch fractions with different sizes from various sweetpotato varieties were revealed insufficiently.

RESULTS

In this study, we devised a time-saving isolation technique to effectively isolate sweetpotato starch fractions based on granule sizes. The new technique was proved applicable for sweetpotato varieties with different flesh colors. The amylose contents of the isolated starch fractions were in the range 16.49-23.27%. A positive association was observed between amylose content, relative crystallinity of starch fractions and their granule size. Conversely, both the swelling power and water solubility at 95 °C displayed a consistent decline from more than 30 g g-1 to lower than 20 g g-1 as the granule size increased. Tp, To and Tc decreased gradually with an increase of starch granule size, while the medium- or small-sized starch fractions showed higher ΔH. In the first stage of thermogravimetric analysis curves, the weight of the small-sized starch fractions decreased the slowest, but no definite pattern was detected in the second or third stage.

CONCLUSION

Therefore, the newly established technique and the results of this study will help better understand the properties of sweetpotato starch fractions with different sizes and certainly provide guidelines for the utilization of sweetpotato starch in food processing and product development. © 2024 Society of Chemical Industry.

Effect of different chain-length fatty acids on the retrogradation properties of rice starch

In order to delay the retrogradation of rice starch, the effects of three different chain length fatty acids (lauric acid, myristic acid and palmitic acid) on rice starch were studied. The fatty acids with longer carbon chains had strong steric hindrance and hydrophobicity, which formed a more compact structure in the helical cavity of amylose, and significantly reduced degree of expansion, migration of water, short-range ordered structure, number of double helical structures and crystallinity. These structural changes endowed the rice starch-long chain fatty acid complexes with better gel viscosity, liquid fluidity and thermal stability than in the rice starch-short chain fatty acid complexes. The results showed that fatty acids with longer chain length inhibited the retrogradation of rice starch, most obviously when 5% palmitic acid was added. This study provides an important reference for the processing of rice starch-based foods.

Strategies and Methodologies for Improving Toughness of Starch Films

Starch films have attracted increasing attention due to their biodegradability, edibility, and potential use as animal feed from post-products. Applications of starch-based films include food packaging, coating, and medicine capsules. However, a major drawback of starch-based films is their brittleness, particularly under dry conditions, caused by starch retrogradation and the instability of plasticizers. To address this challenge, various strategies and methodologies have been developed, including plasticization, chemical modification, and physical reinforcement. This review covers fundamental aspects, such as the microstructures, phase transitions, and compatibility of starch, as well as application-oriented techniques, including processing methods, plasticizer selection, and chemical modifications. Plasticizers play a crucial role in developing starch-based materials, as they mitigate brittleness and improve processability. Given the abundance of hydroxyl groups in starch, the plasticizers used must also contain hydroxyl or polar groups for compatibility. Chemical modification, such as esterification and etherification, effectively prevents starch recrystallization. Reinforcements, particularly with nanocellulose, significantly improved the mechanical properties of starch film. Drawing upon both the literature and our expertise, this review not only summarizes the advancements in this field but also identifies the limitations of current technologies and outlines promising research directions for future development.

Analysis of differences in physicochemical properties of different sorghum varieties and their influence on the selection of raw materials for winemaking

Sorghum is one of the oldest crops in the world, an important grain crop in northern China, and a major raw material in the liquor-brewing industry. The physicochemical properties, cooking characteristics, and starch quality of sorghum seeds considerably affect the liquor-brewing process.To select suitable sorghums for liquor brewing and to determine the cooking characteristics and starch physicochemical properties of different sorghum varieties, 30 types of sorghum were used in this study, and their compositions were compared; six types of sorghum were further studied for their cooking quality and starch physicochemical and pasting characteristics. Gas chromatography time of flight mass spectrometry was used to analyse the cooking aroma of sorghum seeds. Additionally, scanning electron microscopy, a rapid visco analyser, and a differential calorimetric scanner were used to analyse the microstructure of sorghum starch, starch pasting characteristics, and thermodynamic properties, respectively. The results revealed that the water absorption and saccharification forces of glutinous sorghum were higher than those of japonica sorghum and that the aroma substances were significantly different. Glutinous sorghum starch had high crystallinity, freeze-thaw stability, and enthalpy, thus indicating its structural stability. This study provides a theoretical basis for the selection of wine raw materials in the future.

Variability of amylose content and its correlation with the paste properties of cassava starch

The amylose content can significantly impact the diverse industrial applications of cassava starch. This study aimed to assess the variability of cassava germplasm concerning amylose content and other attributes pertinent to root quality, alongside its correlation with paste properties. Starch extracted from 281 genotypes, obtained in germplasm evaluation trials, was evaluated for amylose content, with additional analysis of parameters such as pasting temperature, time to peak viscosity (TPV), viscosity breakdown (BrD), retrogradation tendency, and maximum, minimum, and final viscosities. The genotypes exhibited considerable variation in dry matter content (ranging from 27.06% to 41.02%), starch content (from 14.61% to 25.67%), cyanogenic compounds (1.77 to 7.81), and amylose content (0.05% to 33.23%). High phenotypic variability in paste properties was observed, alongside a low residual effect for most traits, resulting in high broad-sense heritabilities (>0.95). Strong correlations of significant magnitude (>0.80) were found between parameters such as peak viscosity × viscosity breakdown, minimum viscosity × final viscosity, and final viscosity × retrogradation tendency. Moderate correlations were also identified, such as between dry matter content × starch content (0.56). While positive, correlations between amylose content and paste properties were of low magnitude (ranging from 0.13 to 0.35), except for TPV and BrD. Principal component discriminant analysis clustered the germplasm into six distinct groups based on root quality and paste properties, with most improved genotypes falling into two clusters characterized by high starch and dry matter contents. This study underscores the necessity of simultaneous evaluation of amylose content and paste properties in the breeding pipeline. Additionally, clustering cassava genotypes proves beneficial in identifying those that fulfill specific requirements in industrial and breeding applications.

Three nonconventional starch: Comparison of physicochemical properties and in vitro digestibility

Extraction of starch from waste is also an effective way to recover resources and provide new sources of starch. In this study, starch was isolated from white kidney bean residue, chickpea residue, and tiger nut meal after protein or oil extraction, and the morphology of starch particles was observed to determine their physicochemical properties and in vitro digestibility. All these isolated starches had unique properties, among which white kidney bean starch (KBS) had a high amylose content (43.48%), and its structure was better ordered. Scanning electron microscopy revealed distinct granular morphologies for the three starches. KBS and chickpea starch (CHS) were medium-granular starches, whereas tiger nut starch was a small granular starch. Fourier transform infrared spectroscopy analysis confirmed the absence of significant differences in functional groups and chemical bonds among the three starch molecules. In vitro digestibility studies showed that CHS is more resistant to enzymatic degradation. Overall, these results will facilitate the development of products based on the separation of nonconventional starches from waste.

Molecular mechanism for the influence of yam starch multiscale structure on the sensory texture of cooked yam

Yam is a dual-purpose crop as both medicine and food. However, the mechanism controlling the eating quality of yam remains to be elucidated. This study explored the influence of starch multiscale structure on the texture of yam. The results indicated that FS and RC yam have higher hardness and chewiness, while BZ, XM, and PL yam possess waxiness, Fineness, and Stickiness. Statistically, high amylose (AM) can increase hardness, chewiness, and compactness; and average molecular size (Rh) is positively correlated with stickiness, fineness, and waxiness. Specifically, medium- and long-chain amylose (1000 < X ≤ 10,000) and amylopectin (24 < X ≤ 100), particularly medium-chain amylose (1000 < X ≤ 5000) and long-chain amylopectin (24 < X ≤ 36), primarily affect sensory and rheological stickiness. The long chains of amylose form a straight chain interspersed in the crystalline and amorphous regions to support the entire lamellar structure. Higher proportion of amylose long chains, promoting the starch's structural rigidity, which in turn enhanced its hardness-related attributes. Moreover, a higher ratio of long chains within amylopectin results in tightly intertwined adjacent outer chains, forming double helix crystalline zones. This consequently augmenting the texture quality linked to stickiness-related attributes.

Physicochemical properties of a novel chestnut porous starch nanoparticle

A novel chestnut porous starch nanoparticle (PSNP) was successfully synthesized, combining the properties of starch nanoparticle (SNP) and porous starch. The SNP obtained through ultrasonic and acid hydrolysis, exhibited a smaller particle size (173.9 nm) and a higher specific surface area (SSA) compared to native starch. After the synergistic hydrolysis by α-amylase and glucoamylase, the porous structure appeared on the surface of SNP. The prepared PSNP had a size of 286.3 nm and the highest SSA. In the adsorption experiments, PSNP showed higher capacities for adsorbing water, oil and methylene blue (MB) compared to other samples. The acid and enzymatic treatments resulted in a decrease in the levels of total starch content and amylose ratio. Furthermore, the treatments increased the levels of relative crystallinity (RC) and solubility, while decreasing the short-range ordered structure and swelling ratio at high temperatures. It was observed that the SSA of starch granules positively correlated with the MB and water adsorption capacity (WAC), solubility, and RC. These findings highlight the potential of the novel PSNP as an efficient adsorbent for bioactive substances and dyes.

Different particle sizes of Momordica charantia leaf powder modify the rheological and textural properties of corn starch-based 3D food printing ink

The study determined the effect of incorporating Momordica charantia leaf powder (MCLP) into corn-starch 3D food-printing ink as a functional ingredient. The effects of the particle size (75, 131, and 200 μm) and quantity of MCLP on 3D printing performance, structural, textural, and rheological properties of corn starch gel were evaluated with different concentrations (5, 10, and 15 % (w/w)) of corn starch. The viscoelastic properties of food inks were determined considering their behavior during extrusion and self-recovery after printing. Scanning electron microscope was used to characterize the microstructure. Based on the results, a high starch content (15 %) with 5 % MCLP was more favorable for 3D food printing. In addition, 3D printing performance, textural and rheological properties of formulated ink was mainly governed by the particle size of MCLP. The food ink with a 5 % mass fraction of 200 μm MCLP had the highest printing precision and the best masticatory properties.

Impact of molecular structure of starch on the glutinous taste quality of cooked chestnut kernels

Chestnuts are a starchy food with a characteristic glutinous taste that is often used to assess their quality. In this study, our findings indicated that chestnuts with higher glutinous taste quality had lower amylose content and microcrystalline structures, as well as higher subcrystalline structures and relative crystallinity in both the raw and steamed starches. In the leached starch, chestnuts with higher glutinous taste quality had lower amylopectin B1 chains and microcrystalline structure, but higher amylopectin B2 chains, subcrystalline structure and relative crystallinity. These results suggest that amylose content, relative crystallinity, and amylopectin chain length distribution are important factors determining the glutinous taste quality of chestnuts. To further enhance our understanding of these factors, an sensory evaluation model was developed based on textural profile analysis parameters. This study provides valuable insights into the relationship between molecular structure of starch and the glutinous taste quality of starchy foods.

The influence of cooperative fermentation on the structure, crystallinity, and rheological properties of buckwheat starch

The effects of co-fermentation of yeast and Lactiplantibacillus plantarum 104 on buckwheat starch physical properties were investigated by various analytical techniques. To investigate the regulations of starch modification during fermentation and to provide a foundation for improving the performance of modified properties of buckwheat starch food. The pasting properties were decreased by co-fermentation also resulted in a reduction in the relative crystallinity. Scanning electron microscopy (SEM) demonstrated that more holes and a relatively rough granule surface were seen in the co-fermentation group. Fourier transform-infrared spectroscopy (FT-IR) results suggested that co-fermentation fermentation decreased the degree of short-range order (DO) and degree of t1he double helix (DD). The results demonstrated that co-fermentation altered these properties more rapidly than spontaneous fermentation. In conclusion, Lactiplantibacillus plantarum 104 could be used for buckwheat fermentation to improve food quality.

Improving rice eating and cooking quality by enhancing endogenous expression of a nitrogen-dependent floral regulator

Improving rice eating and cooking quality (ECQ) is one of the primary tasks in rice production to meet the rising demands of consumers. However, improving grain ECQ without compromising yield faces a great challenge under varied nitrogen (N) supplies. Here, we report the approach to upgrade rice ECQ by native promoter-controlled high expression of a key N-dependent floral and circadian clock regulator Nhd1. The amplification of endogenous Nhd1 abundance alters rice heading date but does not affect the entire length of growth duration, N use efficiency and grain yield under both low and sufficient N conditions. Enhanced expression of Nhd1 reduces amylose content, pasting temperature and protein content while increasing gel consistence in grains. Metabolome and transcriptome analyses revealed that increased expression of Nhd1 mainly regulates the metabolism of carbohydrates and amino acids in the grain filling stage. Moreover, expression level of Nhd1 shows a positive relationship with grain ECQ in some local main cultivars. Thus, intensifying endogenous abundance of Nhd1 is a promising strategy to upgrade grain ECQ in rice production.

A review on stringiness property of cheese and the measuring technique

This review paper provides a deep understanding of stringiness property in a cheese product. Stringiness is used to describe the extended continuous strand of a molten cheese, especially mozzarella cheese. Stringiness is often described quantitatively by stretch length, as well as qualitative definition which focuses on the dimension of strand and ease of extensibility. Very often, the scope of defining stringiness attributes is limited by the measuring techniques because a complete experimental setup is required to obtain information on both stretch quantity and stretch quality. Among the measuring methods, cheese extensibility rig stands out to be the best method to assess stringiness attribute of a cheese as it is an objective method. In addition, a detailed study on the molecular behavior and interactions among natural and imitation cheese components in delivering stringiness, and the challenges faced therein have been reviewed. Thus, the review provides a foundation for the development of vegan cheese or plant-based cheese with stringiness properties.

Structural, rheological, and gelling characteristics of starch-based materials in context to 3D food printing applications in precision nutrition

Starch-based materials have viscoelasticity, viscous film-forming, dough pseudoplasticity, and rheological properties, which possess the structural characteristics (crystal structure, double helix structure, and layered structure) suitable for three-dimensional (3D) food printing inks. 3D food printing technology has significant advantages in customizing personalized and precise nutrition, expanding the range of ingredients, designing unique food appearances, and simplifying the food supply chain. Precision nutrition aims to consider individual nutritional needs and individual differences, which include special food product design and personalized precise nutrition, thus expanding future food resources, then simplifying the food supply chain, and attracting extensive attention in food industry. Different types of starch-based materials with different structures and rheological properties meet different 3D food printing technology requirements. Starch-based materials suitable for 3D food printing technology can accurately deliver and release active substances or drugs. These active substances or drugs have certain regulatory effects on the gut microbiome and diabetes, so as to maintain personalized and accurate nutrition.

Understanding the structural contributions to the functional properties of chestnut starch high in resistant starch type-2

BACKGROUND

Chestnut has recently attracted attention because of its exceptional functional properties, which are mainly influenced by the structural properties of chestnut starch (CS). In this study, ten varieties of chestnut from the northern, southern, eastern, and western regions of China were selected, and their functional properties, including thermal properties, pasting properties, in vitro digestibility, and multi-scale structural characteristics were characterized. The relationship between structure and functional properties was clarified.

RESULTS

In the varieties that were studied, the pasting temperature of CS was in the range of 67.2-75.2 °C and the pastes displayed diverse viscosity characteristics. Slowly digestible starch (SDS), and resistant starch (RS) of CS were in the range of 17.17-28.78% and 61.19-76.10%, respectively. Chestnut starch from north-eastern China exhibited the highest RS content of 74.43-76.10%. Structural correlation analysis revealed that smaller size distribution, fewer B2 chains, and thinner lamellae thickness contributed to higher RS content. Meanwhile, CS with smaller granules, more B2 chains, and thicker amorphous lamellae displayed lower peak viscosities, stronger resistance to shear, and higher thermal stability.

CONCLUSION

Overall, this study clarified the relationship between the functional properties and the multi-scale structure of CS, revealing the structural contributions to its high RS content. These findings provide significant information and basic data for use in the creation of nutritional chestnut food. © 2023 Society of Chemical Industry.

Gel Rheological Properties and Storage Texture Kinetics of Starches Isolated from Anchote (Coccinia abyssinica (Lam.) Cogn.) Cultivars

Anchote is a tuber crop indigenous to Ethiopia. Starch hydration properties and important gel characteristics which include: color, gel rheological properties (at 2, 4, 6, 8, and 10% starch:water w/w) and gel texture evolution (at 10% starch:water w/w), during 0 to 192 h storage (at 4 °C), of anchote starches isolated from four anchote cultivars (Desta 01, Desta 24, white and red) were evaluated and compared with potato and cassava starches (PS and CS). The lightness (L*) and whiteness scores of the anchote starch ranged up to >95, with slight differences among the cultivars, making them pure starches. Swelling power (SP) and water solubility index (WSI) of the anchote starches increased with increasing cooking temperature (40, 50, 60, 70, 80 and 90 °C), and their rate of increase varied significantly with the control starches, as follows: CS < anchote starches < PS. Anchote starch gels resisted higher stresses before breaking their structure and showed higher elasticity with lower (tan δ)1 values than PS and CS gels. They also had greater viscoelastic moduli even at lower concentrations than the PS and CS gels, and their stability increased with increasing concentration. The study of the gels' texture evolution during storage revealed that anchote starch gels had significantly higher (≥40%) initial and final (after 192 h) hardness and were less adhesive than the PS gel. Despite some significant differences in the studied starch gel quality parameters among the starches from the anchote cultivars, the results suggested their promising potential as additional new materials in the development of food products, specifically as a functional ingredient for the formulation of gel-like products.

Effects of particle size on quality characteristics of stone-milled whole wheat flour

BACKGROUND

Whole wheat flour (WWF) prepared by the direct crushing method preserves all the components of the whole wheat grain. WWF with different particle sizes (180, 150, 125, 106, and 96 μm) was obtained by combining stone milling and particle size sieving technology. The effects of particle size on the proximate composition, farinograph, pasting, thermal, and functional properties, starch microstructure, and Fourier-transform infrared (FTIR) spectroscopy of stone-milled WWF were investigated.

RESULTS

The smaller the particle size of WWF, the higher the damaged starch content. The water absorption, degree of softening, pasting temperature, solubility, and syneresis of WWF increased steadily as the particle size decreased, whereas the peak viscosity, final viscosity, swelling power, water holding capacity, and enthalpy of gelatinization decreased. The scanning electron microscope micrographs revealed that the larger the particle size of WWF, the denser the distribution of starch granules. The β-sheet and β-turn contents of WWF with particle size 180 μm were the highest, reaching up to 33.85% and 39.79%, respectively.

CONCLUSION

The particle size exerted influence on the quality characteristics of stone-milled WWF, and the overall properties of WWF were better at medium particle size. © 2023 Society of Chemical Industry.

Effect of Cooking Method and Enzymatic Treatment on the in vitro Digestibility of Cooked and Instant Chestnut Flour

Microwave treatment, roasting, boiling, and enzymatic treatment were used to prepare cooked and instant chestnut flour, and the in vitro digestibility were compared. Cooking gelatinized the starch and destroyed the granular and crystal structure, increasing starch digestibility. After enzymatic hydrolysis, starches were degraded by 20~24%, and the reducing sugar content of the instant flours increased by 79~94%. Starch digestibility was reduced after enzymatic hydrolysis, however, the estimated glycemic index (GI) increased to 65.1 ~ 77.7 due to the combined effect of increased reducing sugar and decreased starch hydrolysis in the instant flours. The chestnuts treated by 'boiling + enzymes' are still a medium GI food. These findings give guidance for the development of low GI cooked and instant chestnut flour.

Structural and Physicochemical Properties of Starch from Rejected Chestnut: Hydrothermal and High-Pressure Processing Dependence

The quality standards for the export of chestnuts generate large quantities of rejected fruits, which require novel processing technologies for their safe industrial utilization. This study aimed to investigate the impact of high-pressure processing (HPP) and hydrothermal treatments (HT) on the physicochemical properties of rejected chestnut starch. Chestnuts were treated by HPP at 400, 500, and 600 MPa for 5 min and HT at 50 °C for 45 min. In general, all HPP treatments did not induce starch gelatinization, and their granules preserved the integrity and Maltese-cross. Moreover, starch granules' size and resistant starch content increased with the intensity of pressure. Native and HT chestnut starches were the most susceptible to digestion. HPP treatments did not affect the C-type crystalline pattern of native starch, but the crystalline region was gradually modified to become amorphous. HPP-600 MPa treated starch showed modified pasting properties and exhibited the highest values of peak viscosity. This study demonstrates for the first time that after HPP-600 MPa treatment, a novel chestnut starch gel structure is obtained. Moreover, HPP treatments could increase the slow-digesting starch, which benefits the development of healthier products. HPP can be considered an interesting technology to obtain added-value starch from rejected chestnut fruits.

Screening new breeding japonica rice varieties by rice quality, three processing characteristics, and odor characteristics

Rice's yield, cooking, and sensory quality are primary considerations in selecting new breeding rice varieties, which are determined by the rice eating quality such as processing and flavor characteristics. Thus, in this study, to advance the breed of new superior japonica rice varieties, the differences in the rice quality, processing characteristics, and flavor characteristics between 12 newly-bred varieties (H2-36, H2-42, H2-53, H2-59, H2-63, H2-73, H2-74, H2-79, H2-81, H2-82, H2-89, and H2-91) and 1 commercial variety (Kenyu38) were analyzed. The results indicated that H2-42 has a reasonable length-to-width ratio (1.51), high rice yield, good color, reasonable amylose, protein content, excellent water existence index, accessible storage, and the highest taste value. Electronic nose results showed significant differences in aldehydes, ketones, and alcohols among 13 rice varieties. Aroma analysis results showed that H2-42 had the highest n-hexanal (14.63 µg/kg), (E,E)-2,4-nonadienal (37.24 µg/kg), nonanal (19.93 µg/kg), and decanal (4.81 µg/kg); those were important aroma components in cooked rice. The Pearson correlation analysis showed that hardness, springiness, cohesiveness, trough viscosity, peak time, and pasting temperature were the crucial factors that affected rice quality. According to partial least squares regression analysis, total color change, final viscosity, setback, (E)-2-heptenal, and 2-methyl-undecanol were the most important factors that distinguished the rice quality. In conclusion, H2-42 rice was better apparent quality, processing characteristics, and aroma compounds. Therefore, H2-42 has the potential for identification and promotion. PRACTICAL APPLICATION: The results from this study will provide data support for the cultivation, application, and quality improvement of high-quality rice varieties. In addition, it gives new ideas and methods for studying rice eating quality.

Ultrasound-chilling assisted annealing treatment to produce a lower glycemic index of white rice grains with different amylose content

White rice samples, Chai-Nat1 (CN1) and Jasmin rice (KDML105), were treated with the ultrasound-chilling (UC) and combined with annealing treatments (UC + ANN 45, UC + ANN50, and UC + ANN55). Their physicochemical properties and in vitro glycemic index of rice samples were analyzed. UC + ANN treatments presented pasting temperature, gelatinization temperature and crystallinity increased whereas the glycemic index of both rice samples was decreased as compared to its native. Especially, UC + ANN55 treated rice produced the lowest glycemic index and starch hydrolysis. Moreover, UC + ANN treated CN1 rice exhibited delayed gelatinization temperature, increased gelatinization enthalpy, and decreased glycemic index than KDML105 rice. In addition, Pearson's correlation presented that UC + ANN and amylose content had a highly negative correlation with the glycemic index at p < 0.0.1. The result exhibited that UC followed by ANN show an effective way to modify starch granules with delayed starch hydrolysis reduced glycemic index and properties depending on annealing temperature and rice cultivar.

Development of Innovative Candied Chestnuts from Three Chestnut Cultivars Grown in Portugal

The main purpose of this work is the development of a value-added product (candied chestnuts) from Portuguese chestnut (Castanea sativa) cultivars (Martainha, Longal and Judia), as a way to minimize product loss and wastes. To accomplish this goal, the effects of rehydration, cooking, and syrup conditions on composition, textural properties, and colour parameters of candied chestnuts were investigated. The obtained results revealed that the optimal conditions to prepare candied chestnuts with a sweet taste, dark brown colour, with a crispy texture on the outside and smooth texture in the inner flesh were rehydration at 45 °C for a period of 5 h, cooking in a pressure pan for 15 min, and an immersion process with sucrose syrup for two days (syrup with 25% of sucrose on the first day and syrup of 50% of sucrose on the second day). During the process, the drying loss, hydration ratio, and cooking gain of the different cultivars were about 90%, 79%, and 130%, respectively. The total colour difference of candied chestnuts ranged from 24.18 (Longal) to 29.95 (Judia), the stickiness was moderately intense, and the adhesiveness was high for the three varieties. Longal candied chestnuts were the softest and Martainha candied chestnuts were the hardest, the most elastic, and cohesive. Moreover, the candied chestnuts presented a moisture content ranging from 52.70% and 54.23%, amounts of carbohydrates in the range of 88.58 to 91.87 g/100 g d.m, values of protein (6.55–9.51 g/100 g d.m.), values of ash (0.78–1.98 g/100 g d.m.), and fat (0.87–1.58 g/100 g d.m.). In conclusion, the chestnuts of Portuguese cultivars Martainha, Longal and Judia reveal a good potential to produce candied products with high added value.

Effect of freezing-assisted treatment on the formation of stable VII -type complex of fried sweet potato starch and its mechanism

To comprehensively understand the effect of freezing-assisted treatment on the physicochemical properties of the fried sweet potato starch, the structural changes at granular and crystalline level were investigated. The results suggested that the freezing temperature exerted a significant effect on the interactions between sweet potato starch (SPS) and fried oil. With decreasing the freezing-assisted temperature, the gelatinization enthalpy of the fried frozen SPS remarkably increased by 1.5-4.9 J·g^-1 and the transition temperatures of the second peak were elevated from 132.5°C to 136.5-141.1°C compared to that of native SPS, which suggested that more stable V_II -type starch-lipid complexes were formed during frying. This finding was consistent with the results of the X-ray diffractometer that the intensity of the diffraction peak at 20.1° for V-type complex increased sharply as the temperature decreased from 20°C to -80°C, and the corresponding relative crystallinity and R_1047/1022 values were increased from 16.5% and 0.35 to 26.4% and 0.45, respectively. The scanning electron microscopy revealed that the lower freezing-assisted temperature before frying promoted a membrane-like material covered on surfaces. The results showed that decreasing the freezing temperature promoted the formation of stable V_II -type complex during frying. PRACTICAL APPLICATION: The purpose of this study was to comprehensively understand the effect of freezing-assisted treatment on the physicochemical properties of the fried sweet potato starch. These results provided useful information and effective method for producing fried starch-based foods with low digestibility.

Effects and mechanism of sucrose on retrogradation, freeze-thaw stability, and texture of corn starch-tamarind seed polysaccharide complexes

In this work, we investigated the effects of sucrose (0%-30%, w/w) on the pasting properties, retrogradation, freeze-thaw stability, texture, and the possible interaction with corn starch-tamarind seed polysaccharide (CS-TSP) mixtures. Sucrose increased the gelatinization temperature (from 76.4 ± 0.1 to 87.6 ± 0.0°C), peak viscosity (from 3358.0 ± 1.4 to 7732.5 ± 44.5 cP), and final viscosity (from 3514.0 ± 31.1 to 7724.5 ± 142.1 cP) of CS-TSP mixtures. Further, sucrose limited the increase in the storage modulus of the mixture pastes, transfer of bound water to free water, and water syneresis during the freeze-thaw process. Additionally, sucrose resulted in a more complete gel structure with stronger resistance. Scanning electron microscope and fluorescence labeling analysis showed that the presence of sucrose helped in tight entanglement or cross-link between amylose or between amylose and TSP. Thus, these results in this study could help to improve physicochemical properties of starch-based products, such as glue pudding and other starch desserts.

Chestnut Cultivar Identification through the Data Fusion of Sensory Quality and FT-NIR Spectral Data

The world production of chestnuts has significantly grown in recent decades. Consumer attitudes, increasingly turned towards healthy foods, show a greater interest in chestnuts due to their health benefits. Consequently, it is important to develop reliable methods for the selection of high-quality products, both from a qualitative and sensory point of view. In this study, Castanea spp. fruits from Italy, namely Sweet chestnut cultivar and the Marrone cultivar, were evaluated by an official panel, and the responses for sensory attributes were used to verify the correlation to the near-infrared spectra. Data fusion strategies have been applied to take advantage of the synergistic effect of the information obtained from NIR and sensory analysis. Large nuts, easy pellicle removal, chestnut aroma, and aromatic intensity render Marrone cv fruits suitable for both the fresh market and candying, i.e., marron glacé. Whereas, sweet chestnut samples, due to their characteristics, have the potential to be used for secondary food products, such as jam, mash chestnut, and flour. The research lays the foundations for a superior data fusion approach for chestnut identification in terms of classification sensitivity and specificity, in which sensory and spectral approaches compensate each other's drawbacks, synergistically contributing to an excellent result.

Quality characteristics of sand, pan and microwave roasted pigmented wheat (Triticum aestivum)

Present study investigated the effect of sand, pan and microwave roasting on physico-chemical, functional and rheological properties of yellow (YW), purple (PW), and black wheat (BW). All roasting methods enhanced the browning index (BI), water absorption capacity (WAC) and oil absorption capacity (OAC) roasted wheat flour. Microwave roasting showed significantly higher impact on BI (58.61% for YW, 131% for BW and 83.85% for PW) and WAC (47.93% for YW, 44.63% for BW and 32.09% for PW). However, the decrease in density, emulsifying capacity (EC), foaming capacity (FC), total phenolic content (TPC), total flavonoid content (TFC), and total anthocyanin content (TAC), and antioxidant activity was observed on roasted wheat flour. Roasting also affected the pasting properties of wheat flours and peak, trough, breakdown and final viscosity decreased.

Widely targeted metabolomics analysis reveals new biomarkers and mechanistic insights on chestnut (Castanea mollissima Bl.) calcification process

Chestnut calcification is a quality deterioration due to fast water loss, which has been of deep concern for chestnut quality control because its mechanism is unclear. In order to find out the different key metabolites and metabolic pathways related to the occurrence of chestnut calcification, in this study, liquid chromatography-tandem mass spectrometry (LC-MS/MS) based widely targeted metabolomics analysis was performed on chestnuts that were stored at 50%-55% (low relative humidity, LRH) at 25 °C and 85%-90% (high relative humidity, HRH) at 25 °C. A total of 611 metabolites were detected, and 55 differentially accumulated metabolites were identified as key metabolites involved in chestnut calcification process. The decrease in some monosaccharides accompanied with the increase in some unsaturated fatty acids indicated the degradation of chestnut cell wall and cell membrane during calcification process. As a stress response, amino acid metabolism related to membrane stability was significantly activated. In addition, the enhancement of phenylpropanoid biosynthesis pathway and flavonoid biosynthesis pathway characterized by the accumulation of lignin precursors and antioxidants suggested that lignification process was triggered in calcified chestnut. Therefore, the degradation and hardening of the cell wall and membrane damage were proposed to be associated with the calcification occurrence of chestnut. The metabolic profile of chestnut characterized in this study provided new insights into chestnut calcification process and laid a foundation for further chestnut quality control.

Influence of moisture and amylose on the physicochemical properties of rice starch during heat treatment

Moisture and amylose are important factors affecting the quality of heat-treated starches. The amylose content in heat-treated rice starch increased as moisture content (MC) increased from 8% to 30%, but decreased at MC of 70%. With the increase of MC, the paste transmittance, gelatinization temperature, and digestibility of starch increased, whereas the swelling power and enthalpy decreased. The long- and short-range molecular order and the digestive properties of starch with MC ≤ 30% changed moderately, but high MC (70%) gelatinized the starch and drastically changed the physicochemical properties. High amylose content in rice starch led to low long- and short-range molecular order, swelling power, and gelatinization temperature, but increased resistant starch. The results indicated that 30% of MC separates effects of heat treatment of starch, where low MC (≤30%) and high amylose lowers digestibility, which is beneficial for diabetics, while high MC (>30%) promotes solubility and transparency.

Proanthocyanidins from Chinese berry leaves modified the physicochemical properties and digestive characteristic of rice starch

Proanthocyanidins extracted from Chinese berry leaves (CBLPs) were heated with rice starch in aqueous solution to prepare polyphenols-starch complexes. The physicochemical properties of the complexes were characterized with XRD, DSC, RVA and FT-IR and starch constituents were also analyzed with an enzyme method. Results indicated that the addition of CBLPs destroyed the long ordered structure of rice starch rather than the short ordered structure, since the crystallinity decreased from 21.96% to 18.90% and the ratio of 1047 cm^-1/1022 cm^-1 showed little difference, consistent with the lower ΔH of complexes with higher CBLPs content. Additionally, the CBLPs-rice starch complexes showed a significantly lower content of rapidly digested starch (RDS, 45.64 ± 3.25%) than that of the native rice starch (67.76 ± 2.15%). These results indicated that CBLPs complexes with rice starch might be a novel way to prepare functional starch with slower digestion.

Inhibitory effect of chestnut (Castanea mollissima Blume) inner skin extract on the activity of α-amylase, α-glucosidase, dipeptidyl peptidase IV and in vitro digestibility of starches

This study aimed to investigate the inhibitory effect of chestnut inner skin extract (CISE) on the activity of postprandial blood sugar-related enzymes. In total, 12 flavonoids were identified by HPLC-TOF-MS. CISE showed strong and weak inhibition on α-amylase and α-glucosidase, with the IC₅₀ of 27.2 and 2.3 μg/mL, respectively. The inhibition modes of CISE against α-amylase and α-glucosidase were mixed-type and non-competitive type, respectively. Epicatechin gallate noncompetitively inhibited α-amylase, α-glucosidase and dipeptidyl peptidase IV (DPP-IV). Analysis by ultraviolet-visible spectroscopy, fluorescence spectroscopy and circular dichroism suggested that flavonoids altered the hydrophobicity and microenvironment of these enzymes. CISE decreased the starch bioavailability by reducing the enzymatic hydrolysis rate and increasing the fraction of undigested starch. The extract reduced the rapidly digestible starch and increased the resistant starch after incorporation into A-, B- or C- crystallinity starch. Thus, the chestnut inner skin is a useful resource for regulating postprandial blood sugar level.

Transcriptome Sequencing and Differential Expression Analysis Reveal Molecular Mechanisms for Starch Accumulation in Chestnut

Chestnuts are popular edible nuts that are rich in starch. In order to enhance the transcriptomic resources and further understand starch and sucrose metabolism in maturing chestnuts, a comparative transcriptomic study of Chinese chestnut kernels was conducted at three ripening stages (70, 82, and 94 DAF). At 82 and 94 days after flowering (DAF), starch continued to accumulate, and the amylopectin/amylose ratio increased. Transcriptomic profiling of kernels at 70 (stage I), 82 (stage II), and 94 DAF (stage III) indicated that soluble starch synthase and α-1,4-glucan branching enzyme genes are actively expressed at 82 and 94 DAF. The starch degradation enzymes amylase, phosphoglucan phosphatase DSP4, and maltose exporter did not show differential gene expression, while glycogen phosphorylase-encoding unigenes were significantly down-regulated at 94 DAF. In addition to starch and sucrose metabolism, RNA transport, RNA degradation, pyrimidine metabolism, purine metabolism, plant hormone signal transduction, plant–pathogen interactions, and glycerophospholipid metabolism were found to be significantly enriched in all comparisons included in the study. As Chinese chestnut matured, the unique enriched pathways switched from ribosomal biogenesis and RNA polymerase of eukaryotes to endocytosis and spliceosomes. These genomic resources and findings are valuable for further understanding starch and sucrose metabolism in the Chinese chestnut.

A novel starch: Characterizations of starches separated from tea (Camellia sinensis (L.) O. Ktze) seed

The physicochemical, thermal and crystal properties of starches isolated from 3 different tea (Camellia sinensis (L.) O. Ktze) seeds were analyzed in this study. The shape of tea starch granules were flat spherical or oval shape, showed unimodal or bimodal distribution with average size of around 9 μm. Tea starch was typical A-type starch. Apparent amylose contents of three tea seed starches ranged from 27.06% to 33.17%. The chains having degree of polymerization (DP) 13-24 were over 50% of the total detectable chains for tea amylopectin. Peak gelatinization temperature of tea starch ranged from 65 to 77 °C and the water solubility reached up to 9.70%. The peak viscosity of tea starches were as high as 5300 cP and final viscosity ranged from 4000 to 6700 cP. The results indicated that tea seed starch had potential as gel reagents and provide some guides for comprehensive utilization of tea starch in food and non-food applications.