The effect of starch isolation method on physical and functional properties of Portuguese nuts starches. I. Chestnuts (Castanea sativa Mill. var. Martainha and Longal) fruits

The functionality of starch from chestnut (Castanea sativa Mill.) fruits isolated by alkaline and enzymatic methods were assessed. The studied properties included: solubility, swelling power, pasting properties, synaeresis, turbidity, and thermal and rheological behaviours. In addition amylose and resistant starch content were also evaluated. Results showed that the starch isolation method induced changes in most of those properties. Extracted starches (with high contents of amylose and resistant starch) showed low and similar swelling solubility values for all of the samples. Gelatinisation temperatures were also similar (61.5-63.0 °C), but the enzymatic method induced lower consistencies at 95 °C and after holding at this temperature. High values of setback were found, which were clearly affected by the isolation method. This parameter presented lower values for starches isolated by alkaline method (160 BU and 235 BU, respectively for Martainha and Longal). Starches did not present a peak consistency during pasting. Turbidity and synaeresis values were low at room temperature. Synaeresis increased when pastes were stored at low temperatures. This effect was more evident for the material isolated by enzymatic method. All of the isolation starches presented low enthalpy values (3.0-3.5 J/g), but the activation energy was higher for Martainha starches and for starches isolated by A3S method. Pastes showed viscoelastic behaviour, with a predominance of elastic property, forming strong gels after cooling. Longal variety seems to be less resistant to the effect of isolation method. In general starches isolated by the alkali method present the best functional properties as a food ingredient.     

微波对板栗淀粉结构和理化性质的影响

为探讨微波辐照对板栗淀粉颗粒结构和理化性质的影响,采用微波辐照板栗淀粉,通过扫描电镜(SEM)、X射线衍射仪(XRD)、傅里叶变换红外光谱仪(FTIR)、差示扫描量热仪(DSC)等研究微波处理不同时间后板栗淀粉的颗粒结构和理化特性。研究表明:与原淀粉相比,微波处理后板栗淀粉的微观形貌发生明显变化,但淀粉颗粒仍为C型晶体。随着微波处理时间的增加,直链淀粉含量增大,淀粉颗粒表面出现裂纹、孔洞和黏结越显著,淀粉颗粒的相对结晶度降低、红外光谱(1 047/1 022)cm~(-1)峰强度比值降低;淀粉膨胀度和透光率也随微波处理时间的增加而降低。DSC分析表明,微波处理80 s的淀粉相转变温度(T_o和T_p)降低、糊化焓(ΔH)减少。表明微波辐照对板栗淀粉的颗粒结构和理化特征均有显著影响。     

Structural and functional properties of starches from field peas

Starch was isolated from seven varieties of field peas (Pisumsativum L.) and characterised using a combination of physical, chemical and functional tests. The total starch content of the peas ranged between 34% and 42.7% of dry matter, and the amylose content of the starch was between 35% and 38%. Average particle diameter of the seven starches varied between 21.4 and 26.1 μm. All of the pea starches gave a typical C-type X-ray diffraction pattern, with relative crystallinity ranging between 36% and 55% and the proportion of B-type crystallites between 3.8% and 30.4%. Although there were only small differences between the starches in amylose content, they displayed significant variability in functional properties, including swelling power, pasting characteristics, thermal transition temperatures in the differential scanning calorimeter, and in susceptibility to invitro attack by α-amylase. The results indicate the importance of structural characteristics of starch molecules, particularly amylopectin, as determinants of the properties of native starch granules.     

The effect of starch isolation method on physical and functional properties of Portuguese nut starches. II. Q. rotundifolia Lam. and Q. suber Lam. acorns starches

A new starch was isolated from fruits of two acorn species, Quercus rotundifolia and Quercus suber by alkaline (A3S) and enzymatic (ENZ) methods and physical and functional properties were studied. The isolation method induced changes in most of those properties in the isolated starches, mainly in resistant starch content, syneresis, pasting, thermal and rheological properties. Isolated acorn starches presented high amylose content (53–59%) and resistant starch content (30.8–41.4%). Acorn starches showed limited and similar solubility values and swelling power values, showing a gradual increase from 60 °C to 90 °C. The pasting temperatures ranged from 67.5 to 72.0 °C and pastes did not present breakdown, which is suggestive of a high paste stability of acorn starches during heating. At ambient temperature the turbidity and syneresis values were low, but when held at freezing temperatures the syneresis significantly increased. Thermal analysis revealed that the acorn starches easily undergo transition phenomena as shown by the low T_o and enthalpy values (4.1–4.3 J/g), these effects were more evident in starches isolated by ENZ method. Pastes are more elastic than viscous and form strong gels after cooling. Q. suber starch was shown to be more sensitive to the effect of isolation method. Generally, starch isolated by enzymatic method presented less interesting functional properties, since this isolation procedure greater affected the raw structure of starches.     

板栗贮藏前后淀粉性质的比较

为研究板栗贮藏前后淀粉性质的变化,分别测定淀粉的凝沉性、冻融稳定性、透光率、结晶结构、直链与支链淀粉含量、粒度、糊化特性等。结果表明,贮藏后的板栗淀粉较贮藏前其淀粉糊的凝沉加快;冻融稳定性、透明度下降;淀粉颗粒结晶结构未发生变化,仍属于C型;糊化温度降低,峰值黏度上升,稳定性变差,更容易老化。贮藏后板栗淀粉的抗老化能力降低。     

Chemical compositions,fine structure and physicochemical properties of kudzu (Pueraria lobata) starches from different regions

Three commercial kudzu starches from Vietnam, Japan and Korea were used to determine chemical compositions, isoflavone compounds, fine structure and physicochemical properties. The kudzu starch from Vietnam had polygonal granules, whereas the kudzu starches from Japan and Korea contained both polygonal and spherical granules. Total protein, lipid, ash and phosphorus contents present in these kudzu starches were less than 1% (starch basis). The kudzu starch from Vietnam and Korea contained both daidzein and daidzin, whereas the kudzu starch from Japan had only daidzein. These starches had similar actual amylose contents (22.2–22.9%). However, λ_max, blue value and apparent amylose contents of the kudzu starch from Vietnam were lower than those from Japan and Korea. Amylose molecules of the kudzu starch from Vietnam had the largest average degree of polymerization (DP_n) and number of chains (NC), followed by the kudzu starches from Japan and Korea. Amylopectin molecules of the kudzu starch from Vietnam also had the largest DP_n and NC, followed by the kudzu starches from Korea and Japan. X-ray diffraction patterns of the kudzu starches from Vietnam, Japan and Korea were A-type, C-type and B-type, respectively. The kudzu starch from Vietnam was found to have the specific characteristics such as significantly high gelatinization temperature, transition enthalpy and degree of crystallinity as compared to the kudzu starch from Korea and Japan.     

Chestnut and acorn starch properties affected by isolation methods

Starches from chestnut (Castanea sativa Mill.) and acorns (Quercus suber Lam. and Q. rotundifolia Lam.) were isolated from dried fruits using four different methods. These involved a physicochemical and/or an enzymatic treatment followed by centrifugation and sieving: (i) low shear at alkaline pH – LSA, (ii) high shear in water – HSW, (iii) enzymatic treatment at low shear – LSE, (iv) LSA and using successively three sieves – LSA3S. Raw yield, purity, colour parameters, morphology, protein, fat, ash, reducing sugars and amylose contents, damaged starch content and viscoamylographic profiles were studied in isolated starches, presenting different properties through different methods. In general, chestnut starch seems to be poorly resistant to extraction methodologies as shown by the damaged starch content and viscoamylographic properties encountered during this study. Moreover, acorn starches exhibited cross‐linked amylographic patterns. For all the tested raw materials, the LSA3S isolation method always higher yield and purity of starches. Gelatinization temperature and peak consistency were also higher than those shown by starches produced by the other methods, a less damaged structure was also evident. In conclusion, it seems that this method is the most suitable to produce starch for food ingredient usage.     

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.     

Effect of water stress at different stages of grain development on the characteristics of starch and protein of different wheat varieties

The effect of water stress (WS) at 8 and 15 days post anthesis (DPA) on the characteristics of starch and protein separated from C-306, HD-2329, PBW-175, PBW-343 and NI-5439 wheat varieties was studied. WS-induced changes in A-, B- and C-type granules distribution were variety- and stage-dependent. A-type granules increased in response to WS at both stages in all varieties, the extent of increase being greater at 15 DPA. The proportion of B-type granules decreased in all the varieties, except C-306, in response to WS at 15 DPA. C-type granules also decreased in response to 15 DPA in all varieties, except HD-2329. The starch from wheat exposed to WS at 15 DPA showed lower amylose content, lipids content and pasting temperature, and higher peak viscosity, final viscosity and setback. DSC analysis of starches showed two endotherms (associated with the melting of crystallites and amylose–lipid [AML] complexes) during heating, and an exotherm (associated with reforming of AML) during cooling. Transition temperatures (T_o, T_p and T_c) of AML dissociation and association were lower for starch from wheat exposed to WS, the effect being more at 15 DPA. The changes in pasting and thermal properties of starch caused by WS were observed to be related to lipids, amylose content and distribution of granules. The effect of WS on accumulation of different dimethyl formamide-soluble and insoluble proteins was significant and variety dependent.     

Characteristics of native and enzymatically hydrolyzed Zea mays L., Fritillaria ussuriensis Maxim. and Dioscorea opposita Thunb. starches

Comparative studies on glucoamylase hydrolysis of A-type Zea mays L., B-type F. ussuriensis Maxim., and C-type Dioscorea opposita Thunb. were carried out by scanning electron microscope (SEM), X-ray diffractometer (XRD), Fourier transform infrared (FT-IR) spectra and differential scanning calorimetry (DSC). Maize, Fritillaria, Dioscorea starches were hydrolyzed with glucoamylase for 2, 4, 8, 12 and 24 h, respectively. The SEM and XRD results revealed that A-type, B-type starch and C-type starch displayed different hydrolysis mechanisms. A-type starch was digested with enzyme penetrating into starch granules through natural pores on the surface and disrupted the interior of the starch granules. The glucoamylase worked by attacking the surface of B-type starch and forming cracks. When endo-corrosion occurred, the internal part of the granule was corroded through small cracks. However, the glucoamylase primarily attacked the interior of the C-type starch granules and then the exterior of starch granules. FT-IR confirmed that the amorphous regions in the starch granules are firstly hydrolyzed and could be hydrolyzed completely as long as the hydrolysis time is sufficient. The transition temperatures and enthalpy of gelatinization (ΔH_gel) were determined using DSC. According to the gelatinization parameters, it could be further proved amorphous and crystalline structures were hydrolyzed.     

Structural properties and gelatinisation characteristics of potato and cassava starches and mutants thereof

The molecular size of amylopectin (AP) and amylose (AM), AP chain length distribution, crystallinity and granular structure (morphology and granule size distribution) of five wild type potato starches (wtps), five AM free potato starches (amfps), four high-AM potato starches (haps), one wild type cassava starch (wtcs) and one AM free cassava starch (amfcs) were investigated and related to their gelatinisation characteristics. Starches with higher levels of short chains [degree of polymerisation (DP) 6–9 and DP 10–14)] had lower gelatinisation onset (T_o), peak (T_p) and conclusion (T_c) temperatures, whereas higher contents of longer chains (DP 18–25 and DP 25–80) led to higher gelatinisation temperatures. Gelatinisation enthalpies (ΔH) increased with degree of crystallinity. The granules of wtps were larger than those of amfps and haps, respectively. No differences in morphology were observed between wtps and amfps granules, but the haps granules had more irregular surfaces and showed multi-lobed granules.     

Organic acids in two Portuguese chestnut (Castanea sativa Miller) varieties

The organic acids composition of two different chestnut (Castanea sativa Miller) varieties (Judia and Longal) were determined by HPLC/UV. In order to check the influence of the processing over these compounds, samples treated in three distinct manners (roasted, boiled and fried) were also analysed. The results showed that chestnut is characterized by the presence of seven organic acids: oxalic, cis-aconitic, citric, ascorbic, malic, quinic and fumaric acids. The organic acid quantitative profile allows the distinction of the two varieties. Longal variety samples presented higher organic acids contents than those from Judia variety. The contents of the pair malic plus quinic acids may be useful for the discrimination of the two varieties. Roasting, boiling and frying procedures lead to significant reduction of total organic acids contents.     

Preparation and physicochemical properties of modified jackfruit starches

Modifications of jackfruit starch, extracted from the cotyledons of Artocarpus heterophyllus Lam. (Thong Prasert cultivar), were carried out to obtain a pregelatinized starch, three (m-, n- and i-) carboxymethyl starches, a hydroxypropyl starch and a phosphate cross-linked starch. Physicochemical properties of native and modified jackfruit starches were comparatively investigated. Pregelatinized, hydroxypropyl, and cross-linked starches were insoluble or partially soluble in water at room temperature, while carboxymethyl starches were soluble with good overall water uptake. Scanning electron microscopic images revealed that granules of most modified jackfruit starches retained the native appearance and crystal structure, with the exception of pregelatinized starch and two (n- and i-) carboxymethyl starches, which showed significant breakage of granules. X-ray diffraction patterns corroborated to suggest the loss of crystallinity in these modified starches. Thermal analysis showed a significant decrease in the gelatinization temperature of hydroxypropyl starch with no change in enthalpy, while higher gelatinization temperature and less enthalpic value were observed for pregelatinized starch. Pregelatinized and hydroxypropyl starches showed temperature-dependent improvement on swelling and solubility, while cross-linked starch exhibited less solubility. Aqueous solution of m-carboxymethyl starch yielded the highest apparent viscosity with improved heating-cooling stability.     

Properties of starch from root tuber of Stephania epigaea in comparison with potato and maize starches

The dry root tuber of Stephania epigaea contained 36.5% starch, indicating a good starch source. In this study, starch was isolated from S. epigaea. Its morphology, physicochemical, and functional properties were investigated and compared with potato and maize starches. S. epigaea starch had small spherical granules with centric hila and large ellipsoidal granules with eccentric hila, and granule sizes varied from 7 to 40 μm. The starch had 33.9% amylose content and B-type crystallinity. The gelatinization onset, peak, and final temperatures were 59.4, 62.3, and 66.2°C, respectively, and were lower than those of potato and maize starches, but the enthalpy (16.3 J/g) was higher than that of potato and maize starches. The peak, hot, final, and breakdown viscosities were 2227, 1623, 2149, and 594 dPa s, respectively, and were significantly higher than those of maize starch and lower than those of potato starch. S. epigaea starch was more susceptible to amylase hydrolysis and in vitro digestion than potato starch and less than maize starch. This study would be useful for the applications of starch from S. epigaea in the food and non-food industries.     

Effects of high energy milling on some functional properties of jicama starch (Pachyrrhizus erosus L. Urban) and cassava starch (Manihot esculenta Crantz)

In this study, the effect of high energy milling using a Spex ball mixer mill on some functional properties of cassava starch (Manihot utilissima) and jicama starch (Pachyrrisus erosus) were investigated. The properties of individual granules were strongly influenced by the high moisture of ball milling (friction and heat) and physicochemical properties of their amorphous and crystalline zones. High energy milling resulted in a partial fragmentation of the starch granules, increasing the water absorption index (WAI) and the water solubility index (WSI). Increasing moisture content the viscosity was decreased, attributable to the fragmentation of starch granules produced by the milling and favored by the increase of moisture content.The crystallinity of cassava and jicama starches milled with high moisture contents and longer milling times was decreased. Thermal properties of both ball-milled starches were modified. The enthalpies were lower than native starch indicating that ball milling destroys the crystallinity and double helical order arrangements. Also, the resolution of the peaks was slightly decreased. Ball-milled jicama and cassava starches showed some functional characteristics of gelatinization that possibility their use in food systems as stabilizing, additives, moisture retainers and thickeners.     

Properties of Starches from Australian Wheats. Part 2: Some Physico-chemical Properties

Various physico-chemical properties of starches isolated from 21 Australian wheat varieties were assessed. Molecular weights varied between the starches and were lower in those from soft wheats. Proportions of small granules were significantly correlated with starch amylose and protein contents; those of large granules correlated negatively with fat content. Granule crystallinity was correlated with hardness of the parent wheats. Gelatinisation temperatures, measured by differential scanning calorimetry, varied between the starches within the range of 46–79°C. Enthalpies of gelatinisation, 4.6–13.3 J/g of dry starch, were correlated with both amylopectin content and wheat hardness. Minimum moisture for gelatinisation, 0.15–0.56 wa-ter/g of dry starch, was significantly correlated with both amylose and fat contents of the starch.     

Structural characterizations of waxy maize starch residue following in vitro pancreatin and amyloglucosidase synergistic hydrolysis

The objective of this work was to determine if in vitro digestion altered the molecular structure and slow digestion property of waxy maize starch. The Englyst testing on partially hydrolysis residual starches showed an increase of RDS accompanied a reduction of RS with increasing time of digestion, while SDS was almost constant. Scanning electron micrographs showed that the pattern of enzymatic hydrolysis was inside-out layer-by-layer digestion. A threefold decrease in the average molecular weight of starch components was observed after α-amylolysis for 120 min. There were increases in the onset temperature, peak temperature and ratio of absorbance 1047/1022 cm⁻¹, while the enthalpy of gelatinization, crystal structure, and crystallinity invaried. These changes suggest simultaneously enzymatic hydrolysis of both crystalline and amorphous regions of starch granule during in vitro digestion. SDS of starch residue also may consists of layered structure of amorphous and crystallite regions and located periphery of starch granules.     

韧化处理对板栗淀粉特性的影响

以燕山板栗淀粉为材料,在30、40和50℃分别进行韧化处理。采用扫描电子显微镜(SEM)、X-射线衍射分析(XRD)、差示扫描量热分析(DSC)及体外消化法等方法,研究了韧化处理对板栗淀粉颗粒结构、理化特性和体外消化性的影响。研究表明:与原淀粉相比,韧化处理后2种板栗淀粉的直链淀粉含量降低,淀粉颗粒破损率增大,但淀粉仍为C型晶体。随着韧化温度的升高,淀粉颗粒表面出现凹坑和损伤越显著,膨胀度随着处理温度的升高而降低。DSC分析表明,韧化处理使淀粉的糊化温度升高,热焓变化不大。不同的韧化处理温度对板栗淀粉体外消化性有不同的影响,韧化处理使淀粉的快消化淀粉(RDS)含量减少,慢消化淀粉(SDS)含量增大。     

Pisum sativum and Vicia faba Carbohydrates: Structural Studies of Starches

The fine structure of laboratory purified broadbean and smooth pea starches, with an amylose content of 32-34%, has been studied by pullulanase debranching, before or after beta-amylolysis, and by the properties of the chemically fractionated amylose and amylopectin. The enzymatic study has shown the presence of the three chain populations (DP > 60, 45 and 15) observed with other starches. The linear DP 15 and 45 chains occur in a ratio of 8.5 for broadbean and 9.75 for pea, which indicates an amylopectin similar to cereal starches. The λ_max, beta-amylolysis limit and intrinsic viscosity of the two amylopectins confirm the cereal-like nature. The two amylose components are not completely linear according to their beta-amylolysis limit of 81.5% which corroborates the in complete debranching of the total starch. The physical structure, studied by X-ray diffractometry, is of C-type. By submitting legume starch granules to mild acid hydrolysis (lintnerization), a residue has been obtained from both starches, which has an increase in the crystalline fraction, with a tendency towards the A-type pattern for broadbean and the B-type for pea. The crystallites are mainly formed of linear chains (CL 15) with some singly branched material (DP 25). Gelatinization of starch granules occurs at 44-65-86°C for broadbean with a heat of gelatinization of 3.8 cal g^?1 and at 48-61-80°C for pea with a heat of gelatinization of 3.2 cal g^?1.     

Comparative studies on morphological and crystalline properties of B-type and C-type starches by acid hydrolysis

Comparative studies on acid hydrolysis of B-type Fritillaria starch and C-type Rhizoma Dioscorea and Radix Puerariae starches were carried out using a scanning electron microscope (SEM) and X-ray diffraction (XRD). Fritillaria, Rhizoma Dioscorea and Radix Puerariae starches were hydrolyzed with 2.2 mol/L at 35 °C for 2, 4, 8, 16 and 32 days, respectively. The SEM and XRD results revealed that B-type starch and C-type starch displayed different hydrolysis mechanisms. The acid corrosion started from the exterior surface of B-type starch granules followed by the interior core of starch granules. However, the hydrogen ion primarily attacked the interior of the C-type starch granules and then the exterior of starch granules. B-type starch granule started to crack at the hydrolysis period of 4 days while C-type starch granule was not cracked until the hydrolysis progressed up to 16 days. The crystalline type of B-type starch was not changed with increasing hydrolysis time. However, the crystalline type was gradually changed from C-type to A-type for the Rhizoma Dioscorea and Radix Puerariae starches with increase in the hydrolysis time. This result showed that the B-type polymorphs present in the C-type starch granule was preferentially hydrolyzed during the first stage of hydrolysis.