Morphological and physicochemical characterization of starches isolated from chestnuts cultivated in different regions of China

A mechanistic study of chestnut starch retrogradation and its effects on in vitro starch digestion

Starch retrogradation is a mechanism that is associated with the quality of starch-based food products. A thorough understanding of chestnut starch retrogradation behavior plays an important role in maintaining the quality of chestnut foods during processing and storage. In this study, we investigated the effects of storage time on the structural properties and in vitro digestibility of gelatinized chestnut starch by using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and solid-state 13C nuclear magnetic resonance (NMR). The results showed that the long-range crystallinity and short-range molecular order of retrograded chestnut starch first rapidly increased from 3 h to 3 d and then decreased from 3 d to 7 d, followed by a slight increase from 7 d to 14 d with retrogradation. With the extension of storage time at 4 °C, there were generally obvious increases in single and double helical structures, which were stacked into long-term ordered structure, resulting in increased enthalpy changes as detected by differential scanning calorimetry spectroscopy (DSC) and reduction of the digestion rate of retrograded chestnut starch. Overall, this study may provide important implications for manipulating and improving the quality of chestnut foods.

Optimisation of dry heat treatment conditions for modification of faba bean (Vicia faba L.) starch

Faba bean is a protein-rich starchy grain that is underutilised in the UK. The starch of faba bean can be modified using environmentally friendly methods like dry heat treatment (DHT) to enhance functional and its physicochemical properties. This study investigated the impact of dry heat temperature and time on the structure, functional and physicochemical properties of faba bean starch (FBS) using a two-factor central composite rotatable design. Factors (DHT temperature:100-150 °C and DHT time:0.5-5 h) with their respective α mid-point values led to 13 experimental runs. Selected pasting and functional properties were measured as response variables. Corn starch was included as a reference and compared with the FBS modified using the optimized conditions. DHT increased peak (approx. 2205-2267 cP), final (approx. 3525-3642 cP) and setback (approx. 1887-1993 cP) viscosities but decreased the amylose content of FBS. Colour, as measured by lightness value, morphology and crystalline type were not altered but the starches showed a loss of order and an increase in crystallinity after DHT. FBS appeared resilient to DHT but showed higher swelling power and pasting properties compared to the corn starch control. The optimum DHT conditions to produce starch with desirable properties are a temperature of 100 °C for 0.1716 h, with a desirability factor of 66 %.

Starch exploration in Nelumbo nucifera and Trapa natans: Understanding physicochemical and functional variations for future perspectives

The current research emphasis on identifying unconventional starch sources with varied properties to broaden industrial applications. The focus of this research is on the search for alternative sources of starch with different properties in order to expand their potential use in the industrial sector. Starch was extracted from Trapa natans and Nelumbo nucifera and analyzed for their physicochemical and functional properties. They had similar protein (0.35 %) and ash contents, but the nitrogen-free extract was slightly higher in Nelumbo starch (87.58 %) than in Trapa starch (85.09 %). The amylose and amylopectin contents were 23.89 % and 76.11 % in Trapa starch and 15.70 % and 84.30 % in Nelumbo starch, respectively. Fourier-transform infrared spectroscopy identified both as polysaccharides. The characteristic absorption bands assigned to the stretching of OH groups (3324 cm-1; 3280 cm-1), the asymmetric and symmetric stretching of aliphatic chain groups (2925 cm-1; 2854 cm-1), the bending vibration of CHO groups (1149 cm-1; 1144 cm-1) were present in both the starch samples, with the exception of CH3 which could not be detected in Trapa natans starch. X-ray diffraction confirmed hexagonal and orthorhombic crystal structures in Nelumbo nucifera and Trapa natans starch. Scanning electron microscopy revealed a smooth oval and a rough cuboidal shape for lotus and chestnut starch, respectively. Rheological analysis showed that both starch solutions exhibited gel behavior, with Trapa showing stronger gel behavior after the crossover point. These results suggest potential applications in various industries, including the food industry and beyond.

Evaluation of Quality Properties of Brown Tigernut (Cyperus esculentus L.) Tubers from Six Major Growing Regions of China: A New Source of Vegetable Oil and Starch

Tigernut has been recognized as a promising resource for edible oil and starch. However, the research on the quality characteristics of tigernut from different regions is lagging behind, which limits the application of tigernut in food industry. Tigernut tubers were obtained from six major growing regions in China, and the physicochemical properties of their main components, oil and starch, were characterized. Tigernut tubers from Baoshan contained the most oil (30.12%), which contained the most β-carotene (130.4 µg/100 g oil) due to high average annual temperature. Gas chromatography analysis and fingerprint analysis results indicated that tigernut oil (TNO) consists of seven fatty acids, of which oleic acid is the major component. Changchun TNO contained the least total tocopherols (6.04 mg/100 g oil) due to low average annual temperature. Tigernut tubers from Chifeng (CF) contained the most starch (34.85%) due to the large diurnal temperature range. Xingtai starch contained the most amylose (28.4%). Shijiazhuang starch showed the highest crystallinity (19.5%). Anyang starch had the highest pasting temperature (76.0°C). CF starch demonstrated superior freeze-thaw stability (syneresis: 50%) due to low mean annual precipitation. The results could be further applied to support tigernut industries and relevant researchers that looks for geographical origin discrimination and improvements on tigernut quality, with unique physicochemical and technological properties.

Morphological, Structural, Thermal, Pasting, and Digestive Properties of Starches Isolated from Different Varieties of Rice: A Systematic Comparative Study

The aim of this study was to compare the properties of isolated starches from ten commonly consumed rice varieties in China and to investigate their possible association. In addition, principal component analysis (PCA) and correlation analysis were performed to demonstrate the weight or relevance of different properties. The starch granules had an irregular polyhedral structure. The crystalline structure had an orthogonal arrangement, which is characteristic of A-type starch with nanocrystals with an orthorhombic crystal structure. In addition, higher levels of rapidly digestible starch (72.43 to 74.32%) and resistant starch (2.27 to 2.3%) were found in glutinous rice starch. The highest content of slowly digestible starch (59.48%) was found in starch isolated from black rice, which may be an ideal rice variety for controlling blood glucose and weight. Starch isolated from red Hani terrace rice showed the highest thermal stability during cooking and the highest resistance to a high shear force treatment. In addition, the PCA suggests that the amylose content of starch largely determines the functional properties of starch and positively correlates with the peak viscosity and setback viscosity of the starch pasting. The results of this study will enrich the scientific knowledge of various rice starches and promote their application in the food industry and other industries.

Physicochemical Properties of Granular and Gelatinized Lotus Rhizome Starch with Varied Proximate Compositions and Structural Characteristics

As a traditional and popular dietary supplement, lotus rhizome starch (LRS) has health benefits for its many nutritional components and is especially suitable for teenagers and seniors. In this paper, the approximate composition, apparent amylose content (AAC), and structural characteristics of five LRS samples from different regions were investigated, and their correlations with the physicochemical properties of granular and gelatinized LRS were revealed. LRS exhibited rod-shaped and ellipsoidal starch granules, with AAC ranging from 26.6% to 31.7%. LRS-3, from Fuzhou, Jiangxi Province, exhibited a deeper hydrogel color and contained more ash, with 302.6 mg/kg iron, and it could reach the pasting temperature of 62.6 °C. In comparison, LRS-5, from Baoshan, Yunnan Province, exhibited smoother granule surface, less fragmentation, and higher AAC, resulting in better swelling power and freeze-thaw stability. The resistant starch contents of LRS-3 and LRS-5 were the lowest (15.3%) and highest (69.7%), respectively. The enzymatic digestion performance of LRS was positively correlated with ash content and short- and long-term ordered structures but negatively correlated with AAC. Furthermore, the color and network firmness of gelatinized LRS was negatively correlated with its ash content, and the retrograde trend and freeze-thaw stability were more closely correlated with AAC and structural characteristics. These results revealed the physicochemical properties of LRS from different regions and suggested their advantages in appropriate applications as a hydrogel matrix.

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.

Comparison of the fine structure and physicochemical properties of proso millet (Panicum miliaceum L.) starch from different ecological regions

Field experiments were conducted to evaluate the morphology, granule size, fine structure, thermal properties, and pasting properties of starch from a waxy (139) and a non-waxy (297) varieties of proso millet grown in Yulin (YY) and Yangling (YL). Compared with the starches from the two varieties grown in YY, the starches from the two varieties grown in YL exhibited higher relative crystallinities, 1045/1022 cm-1 ratio, and amounts of amylopectin long branch chains (APL) but lower 1022/995 cm -1 ratio, amounts of amylopectin short branch chains (APs), and APs/APL ratios. Starches from YL also synthesized long branch-chain amylopectin to enhance intermolecular interactions and form a stable granular structure, which resulted in increased starch gelatinization temperature, enhanced shear resistance, and reduced setback viscosity. Starch from the waxy (139) variety has good application prospects in the food industry because of its high gelatinization temperature and light transmittance and low setback value, which can be ascribed to its extremely low amylose content, polydispersity index, high molecular weight, and dispersed molecular density. It may serve as a reference for applying proso millet starches in the food industry and developing breeding programs to improve starch quality.

Physiochemical characteristics and sensory properties of plant protein isolates-konjac glucomannan compound gels

In this study, the effects of konjac glucomannan (KGM) at different concentrations on the physiochemical and sensory properties of soy protein isolate (SPI), pea protein isolate (PPI), or peanut protein isolate (PNPI) compound gels were investigated. The results revealed that when the ratio of PNPI to KGM was 90:10, the denaturation temperature of PNPI could be significantly enhanced to 119.32°C by KGM modification. Concerning the textural and microstructural features, the amount of KGM addition had positive correlation with the hardness and chewiness of each compound gel, however, too much KGM addition will cause the unstable internal structure of the PNPI/KGM compound gels (70:30 and 60:40). Furthermore, sensory results indicated that PNPI/KGM (80:20), PPI/KGM (80:20), SPI/KGM (80:20) had great potential to be considered as prototypes for novel plant-based products, which generated the highest acceptance scores of 5.04, 5.94, and 5.36 in each group, respectively.

Starch-Derived Superabsorbent Polymer in Remediation of Solid Waste Sludge Based on Water–Polymer Interaction

The purpose of this study is to assess water–polymer interaction in synthesized starch-derived superabsorbent polymer (S-SAP) for the treatment of solid waste sludge. While S-SAP for solid waste sludge treatment is still rare, it offers a lower cost for the safe disposal of sludge into the environment and recycling of treated solid as crop fertilizer. For that to be possible, the water–polymer interaction on S-SAP must first be fully comprehended. In this study, the S-SAP was prepared through graft polymerization of poly (methacrylic acid-co-sodium methacrylate) on the starch backbone. By analyzing the amylose unit, it was possible to avoid the complexity of polymer networks when considering S-SAP using molecular dynamics (MD) simulations and density functional theory (DFT). Through the simulations, formation of hydrogen bonding between starch and water on the H06 of amylose was assessed for its flexibility and less steric hindrance. Meanwhile, water penetration into S-SAP was recorded by the specific radial distribution function (RDF) of atom–molecule interaction in the amylose. The experimental evaluation of S-SAP correlated with high water capacity by measuring up to 500% of distilled water within 80 min and more than 195% of the water from solid waste sludge for 7 days. In addition, the S-SAP swelling showed a notable performance of a 77 g/g swelling ratio within 160 min, while a water retention test showed that S-SAP was capable of retaining more than 50% of the absorbed water within 5 h of heating at 60 °C. The water retention of S-SAP adheres to pseudo-second-order kinetics for chemisorption reactions. Therefore, the prepared S-SAP might have potential applications as a natural superabsorbent, especially for the development of sludge water removal technology.

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.

Characterization of chestnut starch acetate with different degrees of substitution

Chestnut starch acetates (CSA) with different degrees of substitution (DS) were prepared. The structure and physicochemical properties of CSA were then determined, with scanning electron microscopy showing that most of the CSA granules were damaged and dented, and adhered with increased in DS. X-ray diffraction results indicated that the crystal form of CS and CSA was type C. Chemical structure analysis showed that the starch molecule was grafted with acetyl groups. The transparency, freeze–thaw stability, solubility and swelling power of CSA improved with an increase in DS. The viscosity and stability of CSA were significantly improved and pasting temperatures reduced compared with native CS. The cohesion, hardness, gumminess, chewiness and springiness of CSA decreased with an increase in DS, whereas adhesiveness increased. By comparing the properties of CSA with different DS, a new option was provided for the application of renewable natural polymer CSA in food fields.

Citric acid esterified Glutinous Assam bora rice starch enhances disintegration and dissolution efficiency of model drug

The current work was designed to study the starch's physicochemical attributes, tablet disintegration and dissolution efficiency and its derivatives obtained from the glutinous Assam bora rice (G-ABR) variety of Assam, Northeast India. Starch was isolated by a simple protein denaturation method, and a starch derivative was prepared through citric acid modification. G-ABRS and citrated G-ABRS were characterized through FTIR, DSC, XRD and SEM. The rate of consolidation, consolidation index, angle of internal friction, packing rearrangement and cohesive properties were determined to investigate their applications as functional excipients in pharmaceutical industries. G-ABRS and citrated G-ABRS exhibited better packing rearrangement and cohesive properties than standard corn starch. Furthermore, immediate release of API from the tablet compact was observed when the starch concentration increased from 1 to 5 %, indicating facilitation of the tablet compact disintegration. Therefore, G-ABRS and citrated G-ABRS are potentially functional and sustainable materials for pharmaceutical industries.

Effect of autoclave-cooling cycles combined pullulanase on the physicochemical and structural properties of resistant starch from black Tartary buckwheat

A starch-rich portion is produced as a by-product of black Tartary buckwheat processing. The effect of enzymatic combined with autoclaving-cooling cycles (one, two, or three times) on the physicochemical and structural properties of black Tartary buckwheat type 3 resistant starch (BRS) was evaluated. The autoclaving-cooling cycles enhanced solubility and reduced swelling, with the BRS content increasing from 14.12% to 25.18%. The high crystallinity of the BRS reflected a high molecular order. However, increasing the number of autoclaving-cooling cycles did not result in higher BRS content. The highest BRS yield in the autoclaved starch samples was 25.18% after double-autoclaving-cooling cycles. Furthermore, the autoclaving-cooling cycles altered the crystalline structure of black Tartary buckwheat, and the subsequent crystallinity changed from 36.33% to 42.05% to 38.27%. Fourier-transform infrared spectroscopy shows that the number of cycles results in more efficient double-helical packing within the crystalline lamella. Principal component analysis showed that the autoclaving-cooling cycle treatment leads to significant changes in the molecular structure of resistant starch (RS). These results indicated that autoclaving-cooling cycles might be a feasible way for producing RS from black Tartary buckwheat starch with better structural stability to expand their application range.

Pan-genome analysis of three main Chinese chestnut varieties

Chinese chestnut (Castanea mollissima Blume) is one of the earliest domesticated plants of high nutritional and ecological value, yet mechanisms of C. mollissima underlying its growth and development are poorly understood. Although individual chestnut species differ greatly, the molecular basis of the formation of their characteristic traits remains unknown. Though the draft genomes of chestnut have been previously released, the pan-genome of different variety needs to be studied. We report the genome sequence of three cultivated varieties of chestnut herein, namely Hei-Shan-Zhai-7 (H7, drought-resistant variety), Yan-Hong (YH, easy-pruning variety), and Yan-Shan-Zao-Sheng (ZS, early-maturing variety), to expedite convenience and efficiency in its genetics-based breeding. We obtained three chromosome-level chestnut genome assemblies through a combination of Oxford Nanopore technology, Illumina HiSeq X, and Hi-C mapping. The final genome assemblies are 671.99 Mb (YH), 790.99 Mb (ZS), and 678.90 Mb (H7), across 12 chromosomes, with scaffold N50 sizes of 50.50 Mb (YH), 65.05 Mb (ZS), and 52.16 Mb (H7). Through the identification of homologous genes and the cluster analysis of gene families, we found that H7, YH and ZS had 159, 131, and 91 unique gene families, respectively, and there were 13,248 single-copy direct homologous genes in the three chestnut varieties. For the convenience of research, the chestnut genome database was constructed. Based on the results of gene family identification, the presence/absence variations (PAVs) information of the three sample genes was calculated, and a total of 2,364, 2,232, and 1,475 unique genes were identified in H7, YH and ZS, respectively. Our results suggest that the GBSS II-b gene family underwent expansion in chestnut (relative to nearest source species). Overall, we developed high-quality and well-annotated genome sequences of three C. mollissima varieties, which will facilitate clarifying the molecular mechanisms underlying important traits, and shortening the breeding process.

Transcriptome analysis of walnut quality formation and color change mechanism of pellicle during walnut development

Walnuts (including those covered with a pellicle) are loved for their rich nutritional value. And the popular varieties of walnut cultivation are Juglans sigillata L. The pellicle (seed coat) of these walnut cultivars has different colors and has an indispensable influence on the walnut quality formation. However, there are few reports on the pellicle color and quality formation in different developmental stages of walnut (Juglans sigillata L.). Therefore, in this study, three walnut cultivars (F, Q, and T) with different pellicle colors were selected for transcriptome sequencing and physiological index analysis of the color and quality formation mechanisms at different development stages. The results showed that with the development of walnut fruit, the starch sucrose metabolism pathway in the pellicle was activated and promoted starch hydrolysis. Meanwhile, the expression levels of genes related to the alpha-linolenic acid metabolism pathway were significantly increased during walnut maturation, especially in F2. Some physiological indicators related to lipid oxidation were also detected and analyzed in this study, such as MDA, CAT, POD and DPPH. These results were similar to the expression patterns of corresponding regulatory genes in the RNA-Seq profile. In addition, lignin synthesis genes were up-regulated in the phenylpropanoid metabolic pathway, while key genes enriched in the flavonoid and anthocyanin synthesis pathways were down-regulated. The results were consistent with the results of total anthocyanins and flavonoid content detection during walnut development. Therefore, this experiment suggested that with the maturation of walnut pellicle, the gene expression in the phenylpropanoid metabolic pathway flowed to the branch of lignin synthesis, especially in the Q variety, resulting in lower flavonoid and anthocyanin content at the maturity stage than immature. This is also the main reason for the pale pellicle of the three walnut varieties after mature. The findings of this study showed that changes in the expression levels of regulating genes for lipid, starch, sugar, and flavonoid synthesis during walnut development influenced the accumulation of the related metabolite for walnut quality formation and pellicle color. The results of this experiment provided the molecular basis and reference for the breeding of high nutritional quality walnut varieties.

Influence of Phosphorylation and Acetylation on Structural, Physicochemical and Functional Properties of Chestnut Starch

Chestnut is popular worldwide for its unique flavor, high eating quality and nutrition. Here, we evaluated the influence of phosphorylation and acetylation on the structural, physicochemical and functional properties of chestnut starch. Scanning electron micrographs showed the agglomeration of starch granules and the appearance of numerous dents on the starch granule surface under phosphorylation and acetylation. X-ray diffractograms confirmed that the modification treatments did not affect the C-type crystal pattern, but reduced the relative crystallinity of the chestnut starch, particularly phosphorylation. Moreover, modification improved the paste transparency of the starch. Differential scanning calorimeter analysis revealed that the gelatinization temperature and enthalpy of the starch decreased with the increasing substitution degree, particularly in phosphorylated starch. The Rapid Visco Analyser analysis demonstrated that phosphorylation could greatly improve the pasting properties of chestnut starch. In addition, phosphorylated and acetylated starch had a smaller amount of slowly digested starch and a larger amount of resistant starch relative to native chestnut starch. In conclusion, the functional and physicochemical properties of chestnut starch can be significantly improved through phosphorylation and acetylation, demonstrating its great application potential as a food additive.

Infrared heating under optimized conditions enhanced the pasting and swelling behaviour of cowpea starch

Native starches are not suitable for industrial use and must be modified for improved functionality. In this study, the effect of moisture preconditioning and infrared heating time on physicochemical properties of cowpea starch was investigated using a two-factor central composite rotatable design. Factors (moisture levels:10-40 g/100 g starch and infrared heating time:10-60 min) with their corresponding α mid-point values resulted in 13 experimental runs. Selected functional and pasting properties were determined as response variables. Starch samples produced under optimized conditions were compared with corn starch and their physicochemical properties determined. Except for pasting temperature, cowpea starch prepared using the optimal conditions (moisture: 46.21 g/100 g starch, dry basis and heating time of 32.88 min) had higher functional and pasting properties compared with the native cowpea starch. Infrared heating significantly reduced the gelatinization temperatures of cowpea starch but did not significantly change that of the corn starch. The crystallinity and double-helical order structure of moisture conditioned cowpea starch also reduced after modification. Cowpea starch showed a bigger granule size, higher swelling power but lower water absorption capacities and pasting properties compared with the control. The infrared heating process is a novel and promising modification method for improving the swelling properties of starch.

Morphological and physicochemical characterization of starches from underground stems of Trimezia juncifolia collected in different phenological stages

In this study, starches from underground stems of Trimezia juncifolia were evaluated during dry season (DSS), wet season (WSS) and sprouting (SS). Results evidenced that drought stress did not interfere with the yield, amylose content and degree of polymerization (DP) of amylopectin. However, the extraction yield in SS was 58% lower, being observed and increase of 7.5% in the content of amylose, and 13.5% in DP values for SS amylopectin, with a predominance of A-chains. The amount of total sugar, the starch granules size as well as solubility and swelling properties varied as function of the phenological status. Also, starch granules changed from A-type polymorph in DSS and SS to a C_A-type in WSS. Nevertheless, it was observed a crystallinity reduction from 56% in DSS to 37.1% in SS. In addition, thermograms evidenced the presence of amylose-lipid complexes, with endothermic transition temperatures being affected by drought stress and sprouting. Finally, results demonstrate that underground stems from T. juncifolia have adaptative strategies involving changes in the morphological and physicochemical properties of the starch granules.

Effect of Ultrasonic and Microwave Dual-Treatment on the Physicochemical Properties of Chestnut Starch

This work examined the effect of ultrasound and microwave treatments, separate and in combination, on the physicochemical and functional properties of chestnut starch. The results revealed that the ultrasonic-microwave (UM) and microwave-ultrasonic (MU) dually modified samples exhibited more severe surface damage, weaker birefringence, and lower relative crystallinity and gelatinization enthalpy than the native and single-treated starches. The UM samples showed the highest oil absorption capacity, and the MU samples showed the highest water absorption capacity and the best freeze-thaw stability (five cycles) among all samples. The swelling power, peak, trough, final, and breakdown viscosities, and pasting temperature all decreased regardless of single or dual modification. This study provides a reference for potential industrial applications of ultrasound and microwave treatments for the modification of chestnut starch.