Characterisation of the substituent distribution in hydroxypropylated potato amylopectin starch.
Richardson, S., Nilsson, G. S., Bergquist, K. E., Gorton, L. & Mischnick, P. (2000). Carbohydrate Research, 328(3), 365-373.
The distribution of substituents in hydroxypropylated potato amylopectin starch (amylose deficient) modified in a slurry of granular starch (HPPAPg) or in a polymer ‘solution’ of dissolved starch (HPPAPs), was investigated. The molar substitution (MS) was determined by three different methods: proton nuclear magnetic resonance (1H NMR) spectroscopy, gas-liquid chromatography (GLC) with mass spectrometry, and a colourimetric method. The MS values obtained by 1H NMR spectroscopy were higher than those obtained by GLC–mass spectrometry analysis and colourimetry. The relative ratio of 2-, 3-, and 6-substitution, as well as un-, mono-, and disubstitution in the anhydroglucose unit (AGU) were determined by GLC–mass spectrometry analysis. Results obtained showed no significant difference in molar distribution of hydroxypropyl groups in the AGU between the two derivatives. For analysis of the distribution pattern along the polymer chain, the starch derivatives were hydrolysed by enzymes with different selectivities. Debranching of the polymers indicated that more substituents were located in close vicinity to branching points in HPPAPg than in HPPAPs. Simultaneous α-amylase and amyloglucosidase hydrolysis of HPPAPg liberated more unsubstituted glucose units than the hydrolysis of HPPAPs, indicating a more heterogeneous distribution of substituents in HPPAPg.
Influence of environment on seed soluble carbohydrates in selected lentil cultivars.
Tahir, M., Vandenberg, A. & Chibbar, R. N. (2011). Journal of Food Composition and Analysis, 24(4), 596-602.
High concentrations of raffinose-family oligosaccharides (RFOs) in lentils cause stomach discomfort and reduce lentil quality for human consumption. To develop strategies for lentil quality improvement, we investigated variability, heritability and effects of environmental conditions on the content and composition of soluble carbohydrates in lentil seeds. Analyses of variance showed that cultivar and environment and their interaction had significant effects on the sugar content in lentil seeds. Glucose and sucrose contents of lentil cultivars ranged from 0.02 to 0.06 g and 1.22–1.67 g 100 g-1 lentil meal, respectively. Total RFO content of lentil cultivars ranged from 4.5 to 5.5 mmol
100 g-1 lentil seed meal. In all lentil cultivars, RFO content was positively correlated with glucose and sucrose contents. Analysis of RFO profiles by high performance size exclusion chromatography (HP-SEC) showed that stachyose was the major RFO in all lentil cultivars followed by raffinose and verbascose, respectively. The broad sense heritability of sucrose and RFO estimated from the analyses of variance components was 0.89 and 0.85, respectively. Lentil seed RFO content is a highly heritable trait, thus making it amenable to genetic improvement to meet consumer preferences.
Grain sorghum muffin reduces glucose and insulin responses in men.
Poquette, N. M., Gu, X. & Lee, S. O. (2014). Food & Function, 5(5), 894-899.
Diabetes and obesity have sparked interest in identifying healthy, dietary carbohydrates as functional ingredients for controlling blood glucose and insulin levels. Grain sorghum has been known to be a slowly digestible cereal; however, research is limited on its health effects in humans. The objectives of this study were to measure the contents of functional starch fractions, SDS (slowly-digestible starch) and RS (resistant starch), and to investigate the effects of grain sorghum on postprandial plasma glucose and insulin levels in 10 healthy men. A whole-wheat flour muffin (control) was compared with the grain sorghum muffin with both muffins containing 50 g of total starch. Using a randomized-crossover design, male subjects consumed treatments within a one-week washout period, and glucose and insulin levels were observed at 15 minutes before and 0, 15, 30, 45, 60, 75, 90, 120, 180 minutes after consumption. The mean glucose responses reduced after consuming grain sorghum, particularly at 45–120 minute intervals, and mean insulin responses reduced at 15–90 minute intervals compared to control (P < 0.05). The mean incremental area under the curve (iAUC) was significantly lowered for plasma glucose responses about an average of 35% from 3863 ± 443 to 2871 ± 163 mg (~ 3 h) dL-1 (P < 0.05). Insulin responses also reduced significantly from 3029 ± 965 µU (~ 3 h) L-1 for wheat to 1357 ± 204 with sorghum (P < 0.05). Results suggest that grain sorghum is a good functional ingredient to assist in managing glucose and insulin levels in healthy individuals.
Enzyme-aided investigation of the substituent distribution in cationic potato amylopectin starch.
Richardson, S., Nilsson, G., Cohen, A., Momcilovic, D., Brinkmalm, G. & Gorton, L. (2003). Analytical Chemistry, 75(23), 6499-6508.
The distribution of substituents along the polymer chain in cationic potato amylopectin starch, modified in solution, granular slurry, or dry state, was investigated. The starch derivatives were successively hydrolyzed by different enzymes, followed by characterization of the hydrolysis products obtained by means of electrospray mass spectrometry (ESI-MS) and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). ESI-MS and MALDI-MS were proved to be appropriate techniques for identification of the substituted hydrolysis products, for which there are no standard compounds available. No highly substituted oligomers were found in the hydrolysates, which was taken as an indication of a more or less homogeneous distribution of cationic groups in the amylopectin molecules. Furthermore, from the results obtained it was suggested that the enzymes cleave glucosidic linkages only between unsubstituted glucose units and, preferentially, linkages in sequences containing more than two adjacent unsubstituted units. The determination of the amount of unsubstituted glucose produced from every successive hydrolysis step revealed slight differences between the different starch samples with respect to the homogeneity of the substitution pattern. Among the three samples under investigation, starch cationized in solution was found to have the most and dry-cationized starch the least homogeneous distribution of substituents.
Nutritional and rheological characterization of spray dried sweetpotato powder.
Grabowski, J. A., Truong, V. D. & Daubert, C. R. (2008). LWT-Food Science and Technology, 41(2), 206-216.
Spray drying feasibility of sweetpotato puree is enhanced using alpha-amylase treatment to reduce puree viscosity and maltodextrin (MD) addition to facilitate drying. To better determine potential applications of powders produced with various levels of amylase and MD, nutrient composition and rheological properties of the hydrated spray dried sweetpotato powders were examined and compared with sweetpotato puree. Proximate composition, beta-carotene, vitamin C, and mineral analyses were performed. Steady shear rheology of reconstituted powder solutions was also evaluated at different temperatures and shear rates. Spray drying significantly reduced the β-carotene and ascorbic acid contents. Additionally, the all-trans form of beta-carotene was further transformed to the cis-isomers during dehydration. The viscosity of the reconstituted solutions was much lower than that of the puree at the same solid concentration. Rheologically, the reconstituted sweetpotato slurries behaved similarly to pregelatinized starch solutions. Thus, spray dried sweetpotato powders have a potential to enhance food systems as a thickener despite the need for increased nutrient retention.
Effect of alkali treatment on structure and function of pea starch granules.
Wang, S. & Copeland, L. (2012). Food Chemistry, 135(3), 1635-1642.
The effect of alkaline treatment on the structural and functional properties of pea starch granules was studied using a range of characterization methods including amylose content, scanning electron microscopy (SEM), X-ray diffraction (XRD), 13C nuclear magnetic resonance (NMR), swelling power, differential scanning calorimetry (DSC), the Rapid Visco Analyser (RVA) and in vitro digestibility. The amylose content decreased by about 20–25% after 15 days of alkaline treatment and there were small decreases in relative crystallinity and double helix content. Deformations were observed on the surface of alkali-treated granules, and there was evidence of adhesion between some of the granules. There was a 25–30% reduction in peak and final RVA pasting viscosities, but only a small reduction in swelling power. The endothermic transition of alkali-treated starch was broadened with a shift of the endothermic peak to higher temperature. However, the endothermic enthalpy remained largely unaffected. Alkali-treatment greatly increased the rate of in vitro enzymatic breakdown of the pea starch. More prolonged alkaline treatment for 30 days did not cause further significant changes to the structural and functional properties of the starch granules. The effects of alkali on structure and function of pea starch are explained on the basis of limited gelatinization of the granules.
Anti-digestion properties of amylosucrase modified waxy corn starch.
Zhang, H., Chen, Z., Zhou, X., He, J., Wang, T., Luo, X., Wang, L. & Wang, R. (2017). International Journal of Biological Macromolecules, 109, 383-388.
Amylosucrase is a valuable enzymatic tool for the preparation of resistant starch (RS). This study investigated the morphology, thermal properties and molecular structure of the RS components resulting from the digestion of amylosucrase modified starches (MSs). Morphology of starch samples suggests that the surface of MSs is partially attacked by the digestion enzymes. Besides, the peak melting temperature of RSs shows a considerable increase compared with that of the corresponding MSs. Branch chain length distributions data reveals that the long branch chains of MSs are prone to being hydrolyzed, and the branch chains with degree polymerization of 22-32 are the largest populations among the RS components. Moreover, the RS content in MSs decreases significantly after thermal treatment. Overall results demonstrates that the existence of crystalline structure with thermostable double helices is responsible for the anti-digestion properties of modified starches.
Perspectives for the microbial production of methyl propionate integrated with product recovery.
Pereira, J. P., van der Wielen, L. A. & Straathof, A. J. (2018). Bioresource Technology, 256, 187-194.
A new approach was studied for bio-based production of methyl propionate, a precursor of methyl methacrylate. Recombinant E. coli cells were used to perform a cascade reaction in which 2-butanol is reduced to butanone using alcohol dehydrogenase, and butanone is oxidized to methyl propionate and ethyl acetate using a Baeyer-Villiger monooxygenase (BVMO). Product was removed by in situ stripping. The conversion was in line with a model comprising product formation and stripping kinetics. The maximum conversion rates were 1.14 g-butanone/(L h), 0.11 g-ethyl acetate/(L h), and 0.09 g-methyl propionate/(L h). The enzyme regioselectivity towards methyl propionate was 43% of total ester. Starting from biomass-based production of 2-butanol, full-scale ester production with conventional product purification was calculated to be competitive with petrochemical production if the monooxygenase activity and regioselectivity are enhanced, and the costs of bio-based 2-butanol are minimized.