淀粉质原料在普鲁兰多糖生物合成中的作用及生理机制

为了考察不同淀粉质原料对出芽短梗霉生物合成普鲁兰多糖的影响,本文分别选用来源于木薯、玉米、马铃薯、红薯和小麦等作物的淀粉作为碳源发酵生产普鲁兰多糖。结果发现,木薯淀粉有利于普鲁兰多糖的生物合成,最高产量达到23.96 g/L;红薯淀粉则不利于普鲁兰多糖的合成,显著（P<0.05）降低了普鲁兰多糖的产量和分子量。进一步地,对普鲁兰多糖分批发酵动力学参数和生理学指标进行分析比较,发现木薯淀粉提高了普鲁兰多糖合成关键酶活性和胞内前体物质尿苷二磷酸葡萄糖的含量,进而提高了普鲁兰多糖的合成能力和产量;而红薯淀粉则提高了普鲁兰多糖降解酶活性,显著（P<0.05）降低了普鲁兰多糖的分子量。对普鲁兰多糖分批发酵碳源成本进行估算,发现利用木薯淀粉合成普鲁兰多糖的碳源成本只有葡萄糖对照组的56.6%。该研究结果为普鲁兰多糖的廉价高效生产提供了可行的技术参考。     

Molecular Composition of Starches from Growing Potato Tubers

The changes in the molecular distribution of potato starch during the growth of tubers is determined by GPC (Sephacryl gel systems). After n-butanol fractionation of amylose and amylopectin an efficient statement of the molecular weight alteration of the starch components is observed. Amylopectin of young immature tubers shows a narrow highmolecular weight distribution whereas the amylopectin of mature tubers have a broader distribution with low- and highmolecular weight portions. Also the branched structure is different regarding starch of small and big tubers. Amylose shows a continous increase of the molecular weight. The range up to 0.2 · 10⁶ Dalton is diminished, the molecular weight range over 1.2 · 10⁶ Dalton is increased. The range in between rests nearly constant. These changes in the molecular composition are observed by different potato varieties, Conny and Sieglinde. Clear differences between the amyloses and amylopectins of these two varieties are noticed. The starch components of Sieglinde have always lower molecular weights as Conny starches, just so the overlapping range is much broader.     

Effect of peeling and unpeeling on yield,chemical structure,morphology and pasting properties of starch extracted from three diverse potato cultivars of Pakistan

The current study investigates the comparison and quality characteristics of starches isolated from potatoes using different processing methods from three commercial varieties: Lady Rosetta, Asterix and Challenger, for the first time in Pakistan. The analysis of variance revealed that starch yield significantly (P < 0.05) depended on total solids, peeling (12.7%, 12.0% and 12.0%) and unpeeling (15.0%, 14.0% and 14.0%) of potatoes compared to potato varieties for Lady Rosetta, Challenger and Asterix, respectively. Moreover, pasting properties, protein content, redness and yellowness were increased in those starches isolated without peeling while carbohydrates and lightness were increased in peeled potato starches. Furthermore, Fourier-transform infrared spectroscopy analysis revealed that protein (1200–1400 cm⁻¹) was present in starch extracted without peeling. Besides, scanning electron microscopy analysis revealed oval-shaped starch granules with no impurities in peeled potato starch. The findings suggest the suitability of peeling process for obtaining a high-quality pure starch.     

Short-chain fatty acid content and pH in caecum of rats fed various sources of starch

Caecal pH and contents of short-chain fatty acids (SCFA) were registered in rats fed three potential sources of resistant starch (RS); raw pea starch, raw potato starch, and an RS-enriched preparation obtained from wheat starch by autoclaving and enzymatic incubation. Small intestinal digestibility and delivery of RS to the hind-gut in the case of raw starches were determined by analysis of faecal starch in animals treated with antibiotics to prevent hind-gut fermentation. RS content in the RS-enriched preparation was determined as total starch remaining in an enzymatic gravimetric dietary fibre residue. The fermentability of RS was estimated from the faecal recovery of starch in normal animals with intact hind-gut microflora. Approximately 35 g per 100 g and 32 g per 100 g were RS in the case of raw potato starch and the RS-enriched preparation, respectively, versus only 1 g per 100 g in the case of raw pea starch. The caecal pH decreased with all test diets, being most significant with raw potato starch. SCFA production and faecal bulking were negligible with raw pea starch, whereas both raw potato starch and the RS-enriched preparation significantly increased these parameters. The fermentability of RS in raw potato starch and the RS-enriched preparation was similar, or about 60–70%. If calculated on basis of fermented amount, RS in raw potato starch was more potent in generating SCFA (49 μmol g^?1) than in the RS-enriched preparation (19 μmol g^?1). RS in raw potato starch also displayed the highest faecal bulking capacity. In fact, the faecal dry weight increased more than expected merely from delivery of RS. The relative proportion in caecal contents of acetic-, propionic- and butyric acid was 70, 17 and 8%, respectively, with no significant differences between the three sources of RS.     

Rapid Estimation of Potato Tuber Quality by Near‐Infrared Spectroscopy

Starch and protein parameters of potato tubers were estimated by near‐infrared (NIR) spectroscopy measurements of the crude potato mash. Calibration was carried out with a condensed data set of original 1481 individual samples from a varying number of varieties and breeding lines, grown at eight locations over a three‐years period. Validation of the models was performed with an independent data set (n = 133). Starch content of potato tubers was determined with the official under‐water weighting procedure of the EU, and could be predicted with 90% confidence. The NIR model of phosphorus content of starch had a prediction confidence of 53%. Total protein content could be predicted, too (62% confidence), whereas the amount of coagulable protein was not predictable (R² = 0.25). Despite the different qualification levels of the models, guiding to concrete prediction tools or to a very rough estimation graduating from “low” to “high”, the NIR technique enables potato starch processing plants to optimise both potato starch quality and processing efficiency.     

Nuclear Magnetic Resonance Studies of Homopolysaccharides Related to Starch

One- and two-dimensional ¹H and ¹³C NMR spectra were obtained for a variety of homopolysaccharides, including the glucans dextran and pullulan, and the fructans levan and inulin. The NMR results provided information about the primary structure of these polysaccharides. Our results are in agreement with those determined previously by methylation analysis and other classical methods. The number of α(1 → 44) and α(1 → 6) linkages could be quantitated for pullulan. The presence of a single nonreducing glucose residue in the polyfructose inulin could also be demonstrated. In the case of the branched polysaccharides dextran and levan, it was possible to determine the degree of branching. In addition for lower molecular weight polysaccharides such as inulin and partially hydrolyzed dextran, it was possible to detect signals arising from reducing and non-reducing end groups. Their approximate molecular weight could be determined by quantitation of these signals.     

Purification and Characterization of a Pullulan-Hydrolyzing Glucoamylase from Sclerotium rolfsii

The pullulan-hydrolyzing enzyme from the culture filtrates of Sclerotium rolfsii grown on soluble starch as a carbon source has been purified by ultrafiltration (Amicon, PM-10), ion-exchange chromatography (DEAE-Cellulose DE-52) and gel filtration chromatography (Bio-Gel P-150). The enzyme moved as a single band in non-denaturing polyacrylamide gel electrophoresis carried out at pH 2.9 and 7.5. The relative molecular mass of the enzyme was estimated to be 64.000 D by SDS-PAGE and 66.070 D by gel filtration on Bio-Gel P150. The enzyme hydrolyzed pullulan optimally at 50°C between pH 4.0–4.5, whereas, soluble starch was optimally hydrolyzed at a pH of between 4.0–4.5 and at 65°C. The Michaelis constant (Km) for pullulan was 5.13mg·ml⁻¹ (V_max 1.0U · mg⁻¹) and for soluble starch, it was 0.6mg · ml⁻¹ (V_max 8.33 U · mg⁻¹). The enzyme was observed to be a glycoprotein (12–13% carbohydrate by weight) and had a strong affinity for Concanavalin A. The enzyme hydrolyzed α-D-glucans in an exo-manner, which resulted in the release of glucose as the sole product of hydrolysis. Acarbose, a maltotetraose analog, was found to be a potent inhibitor of both pullulan and starch hydrolysis (100% inhibition at 0.06 μM). The enzyme has been characterized as a glucoamylase (1,4-α-D-glucan glucohydrolase, EC 3.2.1.3) showing a significant action on pullulan.     

不同品种马铃薯雪花全粉品质特性与分子结构表征

本文利用扫描电子显微镜、理化分析方法、红外及二维相关光谱技术对4个品种马铃薯雪花全粉的微观结构、理化品质以及分子结构进行表征,为有效筛选马铃薯雪花全粉加工专用品种提供参考。结果表明:由于生产加工过程中采用真空干燥再粉碎的方法使得4个品种马铃薯雪花全粉中的淀粉颗粒结构均被不同程度的破坏,4个品种马铃薯雪花全粉的碘蓝值、溶解度、膨胀度、冻融稳定性及老化特性差异显著（p<0.05）,4个品种马铃薯雪花全粉原始光谱的吸收峰非常相似,对原始光谱1500⁷00 cm^-1波段进行二阶导数处理后,4个品种马铃薯雪花全粉在波数1200、1300、1330 cm^-1处的二阶导数光谱存在明显差异,基于二维同步相关光谱可知依据1650 cm^-1处自动峰的有无以及强弱,可对4个品种马铃薯雪花全粉进行鉴别。      

Physical properties of starch of Asian-adapted potato varieties

Starch was purified from 24 potato (Solanum tuberosum L) genotypes (varieties and breeding selections) intended for production in Philippine conditions. Genotypes varied widely in their thermal, pasting and other physicochemical properties. The locally bred Philippine varieties and selected advanced clones had comparable starch qualities to the more widely grown commercial varieties from Europe and the USA. The genotypes B71-240.2, LBR 1–5, and the three TPS hybrids (Serrana × LT-7, HPS 7/67 and HPS II/67) had some starch properties that could make them suitable for processing and starch production. Other genotypes have unique properties that could be useful for industrial or other purposes. The addition of 10 g litre⁻¹ NaCl solution significantly decreased and stabilized starch pasting values of all the potato genotypes, but genotypes varied in their relative response to 10 g litre⁻¹ NaCl. © 1999 Society of Chemical Industry     

Retrogradation of Potato Starch as Studied by Fourier Transform Infrared Spectroscopy

Retrogradation kinetics for a potato starch-water system (10% w/w gel) was monitored by Fourier Transform Infrared spectroscopy and compared with waxy maize starch. The spectra showed the C-C and C-O stretching region (1300-800 cm⁻¹) to be sensitive to the retrogradation process. A multi-stage process was observed during the retrogradation of potato starch and characterized as the formation of short- and long-range order. The first stage was characterized as the formation of helices and the fast formation of crystalline amylose regions. The second stage was described as the induction time for amylopectin helix aggregation. Stage three was described as the helix-helix aggregation and the crystallization of amylopectin. The overall-first order calculated rate constant of potato starch was (9.6±1.4) 10⁻ 3h⁻¹. The calculated rate constant were in agreement with the known difference in retrogradation kinetics of waxy maize and potato starch. The effects were explained by the differences in retrogradation rate of amylopectin and amylose. Potato starch consists of amylose as well as amylopectin. Whereas amylose crystallization occurs within a few hours, amylopectin crystallization is slow and takes a few weeks.     

Characterization of Residues from Partially Hydrolyzed Potato and High Amylose Corn Starches by Pancreatic α‐Amylase

High amylose corn starch (HACS) and potato starch were hydrolyzed by pancreatic α‐amylase in vitro. Residues after hydrolysis were collected and characterized for their physicochemical properties and molecular structure. Compared with raw starches, residues had lower apparent amylose contents and higher resistant starch contents. The gelatinization enthalpy of residues from HACS increased while enthalpy of residues from potato starch decreased from 15.4 to 11.3 J/g. Peak viscosity and breakdown values of the residues from potato starch were markedly decreased but final viscosity values did not show much change. Chain length distribution of debranched amylopectin from the residues indicated that the relative portion of short chain in the residue decreased for both starches. More molecules with intermediate chain length (DP 16—31) were found in residue after 48‐h hydrolysis of potato starch.     

Isolation and Molecular Composition of Starch from Roots of Medicago sativa L.

The concentration and molecular composition of starch from alfalfa (Medicago sativa L.) taproots were determined using dimethyl sulfoxide (DMSO) extraction and gel permeation chromatography. Three 24-h extractions with 90% (v/v) DMSO were required to solubilize an average of 97% of the starch from freeze-dried root tissues. Amylopectin comprised approximately 80% of starch isolated from alfalfa roots. The relative proportions of amylose and amylopectin were similar among three diverse alfalfa germplasms and one cultivar even through starch concentrations ranged from 20 to 410 g kg⁻¹ dry weight. Elution profiles of debranched starches from alfalfa taproots contained two pools of low molecular weight chains with degrees of polymerization similar to debranched starches from maize (Zea mays L.), and potato (Solanum tuberosum L.). The molecular composition of starches from these alfalfa germplasms was similar to that commonly observed for most starches from cereals and tubers.     

Preparation and properties of octenyl succinic anhydride modified potato starch

Potato starch was esterified with octenyl succinic anhydride (OSA) in aqueous slurry systems and the major factors affecting the esterification were systematically investigated. The physico-chemical properties of the products were determined by means of Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), X-ray diffraction and a viscosity analyser (VA). The results indicated that suitable parameters for the preparation of OSA starch from potato in aqueous slurry systems were as follows: concentration of starch slurry, 35% (in proportion to water, w/w), reaction period, 3 h, pH of reaction system, 8.0, reaction temperature, 35 °C, amount of OSA, 3% (in proportion to starch, w/w), OSA dilution-fold, 5. The degree of substitution (DS) was 0.017 and the reaction efficiency (RE) was 72 ± 1.8%. FT-IR spectroscopy showed characteristic absorption of the ester carbonyl groups in the OSA starch at 1724 cm⁻¹. SEM and X-ray diffraction revealed that OSA groups acted by first attacking the surface and some pores formed, but OSA modification caused little change in the crystalline pattern of potato starch (DS 0.045). Apparent pastiness measurement indicated that the starch derivatives gelatinized within a shorter time to achieve higher viscosities over the range of designed concentration of OSA potato starch.     

Development and characterization of novel probiotic-residing pullulan/starch edible films

An innovative approach was performed to prepare novel pullulan/starch blended edible films by direct incorporation of multiple probiotic bacterial strains. Various starches different in origin were blended into the pullulan solutions with different ratios. The physical and mechanical properties of the films were investigated in the presence and absence of probiotic cells. An increase in the starch content of pullulan films resulted in a substantial decrease in relative cell viabilities and mechanical properties. Moreover, slight changes in the physical and mechanical properties of the films were observed with the addition of probiotic strains. Pullulan and pullulan/potato starch films were found to be the most suitable carrier matrices, with a maximum relative cell viability of 70–80% after 2 months of storage at 4 °C. The results suggest that pullulan and pullulan/starch films can be used as effective delivery and carrier systems for probiotics.     

A Study of Native and Chemically Modified Potato Starch. Part I: Analysis and Enzymic Availability in vitro

The availability of native and chemically modified potato starch to α-amylase was studied in vitro (distarch phosphate, acetylated distarch phosphate and hydroxypropyl distarch phosphate). Enzyme availability was also related to results obtained during analysis of starch and dietary fibre, The degree of substitution (DS) was determined by ¹HNMR spectroscopy and the substitution sites were evaluated by gasliquid chromatography and mass spectrometry. Substitution with acetyl- and hydroxypropyl groups reduced the availability of drum-dried starch derivatives to α-amylase. In contrast, the susceptibility of raw starch increased after introduction of hydroxypropyl groups. Cross-linking with phosphate only had but minor effects on enzyme availability. The recovery of starch during analysis depended on (a) degree of hydrolysis to glucose (b) whether or not the substitution groups were removed. The lowest yields were observed when analyzing substituted derivatives after boiling and enzymic hydrolysis (60-70%). Enzymically unavailable starch was not recovered as dietary fibre when using an enzymic gravimetric assay.     

Purification and some properties of a novel raw starch‐digesting amylase from Aspergillus carbonarius

A medium was developed to obtain the maximum yield of raw starch‐digesting amylase from Aspergillus carbonarius (Bainier) Thom IMI 366159 in submerged culture with raw starch as the sole carbon source. The amylase was purified to apparent homogeneity by sucrose concentration and ion exchange chromatography on S‐ and Q‐Sepharose (fast flow) columns. SDS‐PAGE revealed two migrating protein bands corresponding to relative molecular masses of 31.6 and 32 KDa. The enzyme was optimally active at pH 6.0–7.0 and 40 °C, was uninfluenced across a relatively broad pH range of 3.0–9.0 and retained over 85% activity between 30 and 80 °C after 20 min incubation. The enzyme was strongly activated by Co²⁺ and only slightly by Fe²⁺, while Ca²⁺, Hg²⁺, EDTA and N‐bromosuccinamide elicited significant repression of the enzyme activity. The enzyme hydrolysed amylopectin (K_m 0.194 mg ml ⁻¹), glycogen (K_m 0.215 mg ml ⁻¹), pullulan (K_m 0.238 mg ml ⁻¹), amylose (K_m 0.256 mg ml ⁻¹) and raw potato starch (K_m 0.260 mg ml ⁻¹), forming predominantly maltose and relatively smaller amounts of glucose. © 2000 Society of Chemical Industry     

Physicochemical properties of cassava,potato and jicama starches oxidised with organic acids

The oxidising effects of organic (acetic, citric and lactic) acids on the physicochemical properties of starches from cassava, potato and jicama were investigated. Cassava starch oxidised with lactic and citric acids had the highest carbonyl contents (5.43 and 5.84 g kg^?1 respectively), while oxidised potato starch had the highest carboxyl contents. Oxidised jicama starch showed the lowest carbonyl and carboxyl contents. Oxidation increased the maximum viscosity of cassava starch (from 426.61 to 670.11 relative viscosity units (RVU)) and jicama starch (from 160.17 to 561.50 RVU) but decreased that of potato starch (from 669.44 to 206.92 RVU). When carbonyl and carboxyl groups were incorporated into jicama starch granules, the resistance of these granules to stirring at constant temperature (holding) increased, as did their final and retrogradation viscosities. However, the behaviour of oxidised cassava and potato starches, as indicated by a Rapid Visco Analyser, was different. The highest values of endotherm enlargement were found for native and oxidised jicama starch, while the lowest values were found for native and oxidised cassava starch. Native and oxidised potato starch had the highest enthalpy values (14.30–18.30 J g^?1), while jicama starch had the lowest (9.50–11.9 J g^?1). The high intrinsic viscosity of native potato starch was attributed to B‐type starch with a longer‐than‐average amylopectin chain length and a lower degree of crystallinity. Oxidised granules showed little erosion in the form of grooves; on the contrary, oxidation left the grains with a very smooth surface. Copyright © 2007 Society of Chemical Industry     

In vitro availability of starch in heat‐treated potatoes as related to genotype,weight and storage time

The objective of the study was to determine the influence of potato variety, weight and storage time after lifting on the glycaemic index (GI) and resistant starch (RS) content predicted from measurement of the rate and extent of in vitro starch hydrolysis, respectively. The potatoes were either boiled, or boiled and subjected to different heat‐cycling conditions selected to promote retrogradation of amylose or amylopectin, respectively. The hydrolysis indices (HI) and predicted GIs of all 19 potato products were high and fell within narrow ranges of 122–144 and 118–138, respectively. No correlation between average weight of the potato tuber and HI was found. Furthermore, there was no difference in HI between potatoes stored for 1–3 or 8–10 months, nor between varieties of new potato and winter potato. However, the HI was significantly lowered by temperature cycling at conditions known to promote retrogradation of amylopectin (6 °C, 48 h) compared with 6 °C for 24 h followed by 70 °C for 24 h. RS content was already substantial in boiled potatoes, 4.5 g 100 g^?1 (starch basis), and could be increased further by temperature cycling, the highest yield obtained, 9.8 g 100 g^?1 (starch basis), following heat treatment at 6 °C for 24 h followed by 70 °C for 24 h; that is at conditions known to favour amylose retrogradation. Copyright © 2004 Society of Chemical Industry     

Amylose and amylopectin molecular fractions and chain length distribution of amylopectin in 12 varieties of Ghanaian sweet potato (Ipomoea batatas) flours

Sweet potato (Ipomoea batatas) is a commonly cultivated root crop in tropical and subtropical regions, including Ghana. Different varieties of sweet potato have been bred, in order to expand its utilisation within the food and industrial sector. This study analysed flours made from 12 recently developed Ghanaian sweet potato varieties in terms of their amylose and amylopectin molecular fractions and amylopectin chain length distribution. Starch content of the sweet potato flours ranged from 49 to 77 g/100 g dry matter, with 11 of the varieties containing above 60 g/100 g dry matter. An orange-fleshed variety, Apomuden, had the lowest amount of starch (48.9 g/100 g dry matter), while the cream-fleshed variety Histarch had the highest (77.3 g/100 g dry matter). The flours from the 12 sweet potato varieties had intermediate amounts of amylose, within the range 10–30 g/100 g dry matter, and showed typical molecular distribution according to size-exclusion chromatography (SEC). The fine structures of amylopectin, as revealed by anion-exchange chromatography, contained features common for starches of C-type X-ray pattern, but some structural differences were also observed.     

Molecular basis of structural makeup of hulless barley in relation to rumen degradation kinetics and intestinal availability in dairy cattle: A novel approach

To date, no study has been done of molecular structures in relation to nutrient degradation kinetics and intestinal availability in dairy cattle. The objectives of this study were to (1) reveal molecular structures of hulless barley affected by structural alteration using molecular spectroscopy (diffuse reflectance infrared Fourier transform) as a novel approach, and (2) quantify structure features on a molecular basis in relation to digestive kinetics and nutritive value in the rumen and intestine in cattle. The modeled feeds in this study were 4 types of hulless barley (HB) cultivars modified in starch traits: (a) normal starch cultivar, (b) zero-amylose waxy, (c) waxy, and (d) high-amylose. The molecular structural features were determined using diffuse reflectance infrared Fourier transform spectroscopy in the mid-infrared region (ca. 4,000–800 cm⁻¹) of the electromagnetic spectrum. The items assessed included infrared intensity attributed to protein amide I (ca. 1,715–1,575 cm⁻¹), amide II (ca. 1,575–1,490 cm⁻¹), α-helix (ca. 1,648–1,660 cm⁻¹), β-sheet (ca. 1,625–1,640 cm⁻¹), and their ratio, β-glucan (ca. 1,445–1,400 cm⁻¹), total carbohydrates (CHO; ca. 1,188–820 cm⁻¹) and their 3 major peaks, structural carbohydrates (ca. 1,277–1,190 cm⁻¹), and ratios of amide I to II and amide I to CHO. The results show that (1) the zero-amylose waxy was the greatest in amide I and II peak areas, as well as in the ratio of protein amide I to CHO among HB; (2) α-helix-to-β-sheet ratio differed among HB: the high-amylose was the greatest, the zero-amylose waxy and waxy were the intermediate, and the normal starch was the lowest; (3) HB were similar in β-glucan and CHO molecular structural makeup; (4) altered starch HB cultivars were similar to each other, but were different from the normal starch cultivar in protein molecular makeup; and (5) the rate and extent of rumen degradation of starch and protein were highly related to the molecular structural makeup of HB. In conclusion, the molecular structural makeup on a molecular basis was related to rumen degradation kinetics and intestinal availability in dairy cattle. The alteration of starch structure in barley grain affects starch structure and the magnitude of protein and β-glucan contents, as well as the protein molecular structure of HB.