R. Andersson

The influence of amylose and amylopectin characteristics on gelatinization and retrogradation properties of different starches

Physico-chemical properties of starch from wheat, rye, barley (waxy, high-amylose and normal-amylose), waxy maize, pea and potato (normal-amylose and high-amylopectin) were studied. Emphasis was given to the amylose (total, apparent and lipid-complexed) and amylopectin characteristics as well as to the gelatinization and retrogradation properties measured using differential scanning calorimetry. The total amylose content varied from ca. 1 % for waxy maize to 37% for high-amylose barley. The amylopectin characteristics were determined by high-performance size-exclusion chromatography after debranching with isoamylase. The weight-average degree of polymerization (DPw) was 26, 33 and 27 for the A-, B-, and C-type starches, respectively. In general, the potato starches exhibited the highest retrogradation enthalpies and the cereal starches the lowest, while the pea starch showed an intermediate retrogradation enthalpy. The data were analysed by principal component analysis (PCA). The DPw showed positive correlation to the melting interval, the peak minimum, the offset temperatures of the retrogradation-related endotherm as well as to the gelatinization and retrogradation enthalpies. However, the high-amylose barley retrograded to a greater extent than the other cereal starches, despite low DPw (24). The amylose content was negatively correlated to the onset and the peak minimum temperatures of gelatinization.

Studies on α-amylase degradation of retrograded starch gels from waxy maize and high-amylopectin potato

Abstract Gelatinized starch gels of waxy maize and high-amylopectin potato were subjected to different time–temperature conditions, aiming at producing extensive amounts of retrograded amylopectin. The purpose was to investigate the impact of amylopectin retrogradation on the resistant starch formation and on the rate of starch digestion with porcine pancreatic α-amylase. Dried non-cycled gelatinized starch gels were used for comparison. Although differential scanning calorimetry measurements indicated higher amounts of retrograded material in the dried temperature-cycled gels no enzyme resistant starch was detected in any of these samples. However, all cycled starch gels were less-readily degraded by the enzyme than the non-cycled gels. The chain length distribution in the α-amylolysates was studied by high performance anion exchange chromatography after debranching with isoamylase. The main products of hydrolysis were low molecular weight carbohydrates with a degree of polymerization of 1–9 and various branched dextrins. The chain distribution was uniform in the hydrolysates at the different stages of hydrolysis and independent of storage conditions, indicating that the mode of enzyme action remained unaffected by retrogradation. The waxy maize and high-amylopectin potato starches responded similarly to temperature cycling. It was concluded that temperature cycling resulted in a slower hydrolysis of the amylopectin, a phenomena that could be exploited when developing starchy foods with improved nutritional characteristics.

An oligomer from flaxseed composed of secoisolariciresinoldiglucoside and 3-hydroxy-3-methyl glutaric acid residues.

A straight-chain oligomeric structure composed of five secoisolariciresinoldiglucoside (SDG) residues interconnected by four 3-hydroxy-3-methyl glutaric acid (HMGA) residues (molecular weight ca. 4000 Da) was assigned to the main lignan of flaxseed on the basis of nuclear magnetic resonance spectroscopy (NMR).

Structural features of (1->3),(1->4)-β-D-glucan and arabinoxylan fractions isolated from rye bran.

Abstract A water unextractable fraction from rye bran was isolated by means of a sequential extraction. Gel filtration revealed a homogeneous β-glucan and at least two different arabinoxylans. 1H and 13C NMR spectroscopy were used to identify the structural units in both polysaccharides. The isolated arabinoxylan contained a relatively high amount of unsubstituted xylose residues (56.7%). The molar ratio of cellotriosyl to cellotetraosyl units and the ratio of (1→4) to (1→3)-linkages in β-glucan were determined using high performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD) and 1H NMR, respectively. The molar ratio of cellotriosyl to cellotetraosyl was found to be 1.94. From this, the ratio of (1→4) to (1→3)-linkages was calculated to be 2.34, as compared to 2.31 obtained by 1H NMR, showing that the results from both methods are in close agreement.

Polymeric fractions containing phenol glucosides in flaxseed

Abstract Extract rich in phenolic compounds was obtained from flaxseed with 1,4-dioxane:ethanol (1:1, v/v). This extract (whole polymer) was fractionated by solid-phase extraction into three “polymeric” fractions of comparable polarity. HPLC analyses of the base hydrolysates of the three polymeric fractions showed that they contain the same UV-absorbing components, though at different levels and all contained substantial amounts of a lignan, secoisolariciresinoldiglucoside (SDG). Fractionation of the base hydrolysates by column chromatography, followed by high performance liquid chromatography (HPLC) yielded two pure hydroxycinnamic acid derivatives; 4-O-β- d -glucopyranosyl-p-coumaric acid and 4-O-β- d -glucopyranosylferulic acid, whose structures were identified by nuclear magnetic resonance spectroscopy (NMR). NMR analysis showed all three polymeric fractions to have phenolic and aliphatic components and, in line with HPLC, suggested some structural variations between these fractions. The results of this study suggest that the glucosylated phenolic compounds of flaxseed exist in polymeric structure(s) containing ester linkages.

Arylbutanoid and diarylheptanoid glycosides from inner bark of Betula pendula

From the inner bark of Betula pendula, four new disaccharide glycosides, two of (−)-rhododendrol and two of platyphyllone, were isolated along with a new trisaccharide glycoside of (−)-centrolobol and several known compounds. The structures were elucidated by high field 1H and 13C NMR spectroscopy. Assignments of 1H and 13C NMR spectra were made by H,H- and C,H-COSY.

Structural studies on water-soluble arabinoxylans in rye grain using enzymatic hydrolysis

Abstract The major water-soluble arabinoxylan fraction from rye grain, containing 4-linked β- d -xylopyranosyl residues of which about 43% were substituted solely at O-3 and 7% at both O-2 and O-3 with terminal α- l -arabinofuranosyl units, was hydrolysed to different extents using semi-purified xylanase from Trichoderma reesei. Products were fractionated on Biogel P-2 and structurally elucidated by sugar, methylation and high-field 1H-NMR analysis. Moderate hydrolysis released arabinose, xylose, xylobiose, xylotriose and xylotetraose together with xylo-oligosaccharides (DP ≥ 4) in which one or more of the residues were substituted at O-3 with a terminal arabinose unit. The xylose residues substituted with arabinose units at both O-2 and O-3 became enriched in the remaining polymeric fraction. Extensive hydrolysis with the enzyme released arabinose, xylose and xylobiose as major products together with small amounts of two oligosaccharides and a polymeric fraction. One of the oligosaccharides was identified as xylotriose in which the non-reducing end was substituted at O-2 and O-3 with terminal arabinose units and the other as xylotetraose in which one of the interjacent residues was substituted with arabinose units in the same way. The polymeric fraction contained a main chain of 4-linked xylose residues in which 60–70% of the residues were substituted at both O-2 and O-3 with arabinose units. The semi-purified enzyme contained xylanase and arabinosidase activities which rapidly degraded un- and mono-substituted xylose residues while the degradation of double-substituted xylose residues was much slower. The results show that the mono- and double-substituted xylose residues were present in different polymers or different regions of the same polymer.

Comparison of potato amylopectin starches and potato starches: influence of year and variety

Starches from three potato varieties and their respective transformants producing amylopectin starch were studied over a period of 3 years. The gelatinisation, swelling and dispersion properties were studied using differential scanning calorimetry (DSC), X-ray diffraction, swelling capacity measurements and a Brabender Viscograph. The potato amylopectin starches (PAP) exhibited higher endothermic temperatures as well as higher enthalpies than the normal potato starches (NPS). PAP samples gave rise to an exceptionally sharp viscosity peak during gelatinisation and a relatively low increase in viscosity on cooling. Swelling capacity measurements showed that PAP granules swelled more rapidly, and that the dispersion of the swollen granules occurred at a lower temperature (85 degreesC). Analysis of variance (ANOVA) also revealed that the year influenced the DSC results, and that both year and variety affect some of the Brabender parameters. Furthermore, the PAP and NPS samples were subjected to heat-moisture treatment at three different moisture levels, and the Brabender viscosity properties were studied

Monoaryl and cyclohexenone glycosides from needles of Pinus sylvestris

Abstract The 4′- O -β- d -glucopyranosides of 4-(4′-hydroxyphenyl)-2-butanone [rheosmin] and its 3′-methoxy derivative [zingerone]; the 3- O -β- d -glucopyranosides of 3-hydroxy-1-(4′-hydroxy-3′-methoxyphenyl)-1-propanone [β-hydroxypropiovanillone] and trans -3-hydroxy-1-(4′-hydroxy-3′-methoxyphenyl propene [ trans -coniferyl alcohol]; and the 3′- O -β- d -glucopyranosides of (4 S ,3′ R )-4-hydroxy-4-(3′-hydroxybutyl)-3,5,5-trimethyl-2-cyclohexenone [dihydrovomifoliol] and (4 S ,3′ R )-4-hydroxy-4-(3′-hydroxy- trans -1′-butenyl-3,5,5-trimethyl-2-cyclohexenone [vomifoliol] have been isolated from the needles of Pinus sylvestris and identified.

Effects of cultivar, nitrogen fertilization rate and environment on yield and grain quality of barley

Ten barley cultivars, including covered and naked types, varying in their content of total starch, amylose, protein and β-glucan, were grown in different years, at various locations and nitrogen fertilization rates. The barley cultivars showed a large variation in yield (3250–6690 kg ha−1), thousand kernel weight (40–50 g), bulk weight (660–815 g litre−1), starch (51–67% of DM), protein (8–15% of DM), β-glucan (3·5–5·9% of DM) and ash (1·9–2·5% of DM). The naked cultivar SW 8775 had the highest starch content and the high amylopectin cultivar (SW 7142-92, waxy) had the lowest. The waxy starch barleys had the highest protein content, while the normal starch barleys (Golf and Lina) had the lowest protein content at each N-rate. Higher content of β-glucan was found in the waxy cultivars (5·0–5·9% of DM) and high amylose cultivars (5·6–5·9% of DM) than in the other barley cultivars (3·5–4·8% of DM). The results were evaluated by analysis of variance (ANOVA) and principal component analysis (PCA), and both confirmed that nitrogen fertilization rate was of great importance for the protein content. PCA revealed that protein and β-glucan were negatively correlated with starch and yield. The ANOVA showed that the cultivar factor was significant for all variables, but especially for the β-glucan content, which responded differently to the nitrogen fertilization rate during the 2 years. In this study, environmental effects were generally of less importance than the barley cultivars for the different variables.