Quantitative measurement of total starch in cereal flours and products.
McCleary, B. V., Solah, V. & Gibson, T. S. (1994). Journal of Cereal Science, 20(1), 51-58.
A rapid and quantitative method has been developed for the determination of total starch in a wide range of materials, including high-amylose maize starches and food materials containing resistant starch. The method allows the analysis of 20 samples in 3 h. A single assay can be performed in 2 h. For a range of samples, the total starch values obtained with this method were significantly higher than those obtained with current standard methods. Two assay formats have been developed. In assay format 1, the sample is incubated solubilised with the chaotropic agent dimethyl sulphoxide (DMSO) to gelatinise the starch, which is then solubilised and partially depolymerised by controlled incubation at ∼ 100°C with a defined level of thermostable alpha-amylase. This allowed near-complete solubilisation of most starches. The remaining starch is then solubilised and the starch fragments are converted to maltose and maltotriose by the combined action of highly purified pullulanase and beta-amylase. After volume adjustment and filtration (if necessary), the maltooligo-saccharides are hydrolysed by high-purity amyloglucosidase to glucose, which is measured with a glucose oxidase/peroxidase reagent. This assay format gave quantitative starch determination in all native starch samples, including high-amylose maize starches. In assay format 2, which is applicable to most starches and cereal flours, the DMSO pre-treatment step is omitted. Samples containing glucose and/or maltosaccharide are pre-washed with aqueous ethanol before analysis.
Total starch measurement in cereal products: interlaboratory evaluation of a rapid enzymic test procedure.
McCleary, B. V., Gibson, T. S., Solah, V. & Mugford, D. C. (1994). Cereal Chemistry, 71(5), 501-505.
The precision of an enzymatic procedure for analysis of total starch in cereal flours and products was determined in a comprehensive inter-laboratory study involving 29 laboratories. Test samples represented a range of sample types, including modified and native starches, cereal flours and brans, processed cereal products, animal feeds, and plant material. Results were statistically analyzed according to AOAC guidelines. The procedure was shown to be highly repeatable (relative standard deviation 1.5-7.3%) and reproducible (relative standard deviation 4.1-11.3%). It is now available, in a slightly modified form, as an assay kit. The assay, therefore, provides a convenient alternative to existing procedures for quantitative measurement of starch in cereal products.
Collaborative evaluation of a simplified assay for total starch in cereal products (AACC Method 76-13).
McCleary, B. V., Gibson, T. S. & Mugford, D. C. (1997). Cereal Foods World, 42, 476-480.
A procedure for the quantitative analysis of total starch in plant materials has been developed and subjected to a comprehensive interlaboratory study involving 32 laboratories, in accordance with the protocol for collaborative studies recommended by American Association of Cereal Chemists and AOAC International. The method involved treatment of a sample at approximately 95°C with thermostable α-amylase to obtain starch depolymerization and solubilisation. The slurry is then treated with purified amyloglucosidase to give quantitative hydrolysis of the starch fragments to glucose, which is measured with glucose oxidase/peroxidase reagent. Test samples used in the interlaboratory study included modified and native starches, cereal flours and brans, processed cereal products, animal feeds, and plant material. Results were statistically analysed according to AOAC International guidelines (1). The procedure was shown to be highly repeatable (relative standard deviation 2.1-3.9%) and reproducible (relative standard deviation 2.9-5.0%), and on the basis of these results has gained first approval status with AACC (AACC Method 76-13) and approval as AOAC Method 986.11. The method is more robust than a method previously reported (AACC Method 76-12), and 20 samples can be analysed within 2 hr.
Measurement of total starch in cereal products by amyloglucosidase-alpha-amylase method: collaborative study.
McCleary, B. V., Gibson, T. S. & Mugford, D. C. (1997). Journal of AOAC International, 80, 571-579.
An American Association of Cereal Chemists/AOAC collaborative study was conducted to evaluate the accuracy and reliability of an enzyme assay kit procedure for measurement of total starch in a range of cereal grains and products. The flour sample is incubated at 95 degrees C with thermostable alpha-amylase to catalyze the hydrolysis of starch to maltodextrins, the pH of the slurry is adjusted, and the slurry is treated with a highly purified amyloglucosidase to quantitatively hydrolyze the dextrins to glucose. Glucose is measured with glucose oxidase-peroxidase reagent. Thirty-two collaborators were sent 16 homogeneous test samples as 8 blind duplicates. These samples included chicken feed pellets, white bread, green peas, high-amylose maize starch, white wheat flour, wheat starch, oat bran, and spaghetti. All samples were analyzed by the standard procedure as detailed above; 4 samples (high-amylose maize starch and wheat starch) were also analyzed by a method that requires the samples to be cooked first in dimethyl sulfoxide (DMSO). Relative standard deviations for repeatability (RSD(r)) ranged from 2.1 to 3.9%, and relative standard deviations for reproducibility (RSD(R)) ranged from 2.9 to 5.7%. The RSD(R) value for high amylose maize starch analyzed by the standard (non-DMSO) procedure was 5.7%; the value was reduced to 2.9% when the DMSO procedure was used, and the determined starch values increased from 86.9 to 97.2%.
Measurement of carbohydrates in grain, feed and food.
McCleary, B. V., Charnock, S. J., Rossiter, P. C., O’Shea, M. F., Power, A. M. & Lloyd, R. M. (2006). Journal of the Science of Food and Agriculture, 86(11), 1648-1661.
Procedures for the measurement of starch, starch damage (gelatinised starch), resistant starch and the amylose/amylopectin content of starch, β-glucan, fructan, glucomannan and galactosyl-sucrose oligosaccharides (raffinose, stachyose and verbascose) in plant material, animal feeds and foods are described. Most of these methods have been successfully subjected to interlaboratory evaluation. All methods are based on the use of enzymes either purified by conventional chromatography or produced using molecular biology techniques. Such methods allow specific, accurate and reliable quantification of a particular component. Problems in calculating the actual weight of galactosyl-sucrose oligosaccharides in test samples are discussed in detail.
Sourdough bread: Starch digestibility and postprandial glycemic response.
Scazzina, F., Del Rio, D., Pellegrini, N. & Brighenti, F. (2009). Journal of Cereal Science, 49(3), 419-421.
To evaluate the influence of sourdough fermentation on starch digestibility in bread, four experimental breads were obtained, prepared from two different wheat flours (whole or white) by two different leavening techniques (sourdough and with Saccharomyces cerevisiae). Products were analyzed for their starch, fiber and resistant starch (RS) content and then submitted to in vitro hydrolysis with porcine alpha-amylase. On the same breads, postprandial blood glucose was evaluated in healthy human subjects. Both sourdough fermented breads gave glycaemic responses significantly lower (p < 0.001) than the corresponding products leavened with S. cerevisiae. On the contrary, the presence of fiber did not influence the glycaemic potential of breads. RS levels were higher in the sourdough products, whereas no differences were observed either in the rate of starch hydrolysis or in the degree of polymerization of the starch residues after the in vitro hydrolysis. We may conclude that sourdough fermentation is a technique able to reduce the glycaemic response to bread and that the mechanism does not seem related to the rate of starch hydrolysis.
Strain, biochemistry, and cultivation-dependent measurement variability of algal biomass composition.
Laurens, L. M., Van Wychen, S., McAllister, J. P., Arrowsmith, S., Dempster, T. A., McGowen, J. & Pienkos, P. T. (2014). Analytical Biochemistry, 452, 86-95.
Accurate compositional analysis in biofuel feedstocks is imperative; the yields of individual components can define the economics of an entire process. In the nascent industry of algal biofuels and bioproducts, analytical methods that have been deemed acceptable for decades are suddenly critical for commercialization. We tackled the question of how the strain and biochemical makeup of algal cells affect chemical measurements. We selected a set of six procedures (two each for lipids, protein, and carbohydrates): three rapid fingerprinting methods and three advanced chromatography-based methods. All methods were used to measure the composition of 100 samples from three strains: Scenedesmus sp., Chlorella sp., and Nannochloropsis sp. The data presented point not only to species-specific discrepancies but also to cell biochemistry-related discrepancies. There are cases where two respective methods agree but the differences are often significant with over- or underestimation of up to 90%, likely due to chemical interferences with the rapid spectrophotometric measurements. We provide background on the chemistry of interfering reactions for the fingerprinting methods and conclude that for accurate compositional analysis of algae and process and mass balance closure, emphasis should be placed on unambiguous characterization using methods where individual components are measured independently.
Production of high-starch duckweed and its conversion to bioethanol.
Xu, J., Cui, W., Cheng, J. J. & Stomp, A. M. (2011). Biosysystems engineering, 110(2), 67-72.
Growing high-starch duckweed for its conversion to bioethanol was investigated as a novel technology to supplement maize-based ethanol production. Under the fall (autumn) climate conditions of North Carolina, the biomass accumulation rate of Spirodela polyrrhiza grown in a pilot-scale culture pond using diluted pig effluent was 12.4 g dry weight m-2 day-1. Through simple transfer of duckweed plants into well water for 10 days, the duckweed starch content increased by 64.9%, resulting in a high annual starch yield of 9.42 × 103 kg ha-1. After enzymatic hydrolysis and yeast fermentation of high-starch duckweed biomass in a 14-l fermentor, 94.7% of the theoretical starch conversion was achieved. The ethanol yield of duckweed reached 6.42 × 103 l ha-1, about 50% higher than that of maize-based ethanol production, which makes duckweed a competitive starch source for fuel ethanol production.
High hydrostatic pressure influences antinutritional factors and in vitro protein digestibility of split peas and whole white beans.
Linsberger-Martin, G., Weiglhofer, K., Thi Phuong, T. P. & Berghofer, E. (2013). LWT-Food Science and Technology, 51(1), 331-336.
Legumes are of high nutritional value but consumption is low in Western countries due to long processing and antinutritional factors. The development of convenience products can help to overcome these constraints. The present study investigated the effect of high hydrostatic pressure on oligosaccharides, phytic acid and total phenolic acid content, trypsin inhibitor activity and protein digestibility in peas and beans. Oligosaccharides were significantly reduced through pressurisation by up to 68% in peas and 48% in beans but reduction was lower than in cooked samples (max. 82% in peas and 80% in beans). Phytic acid was reduced by high pressure by up to 36% in peas and 11% in beans. Total phenolic acid content was reduced only in some pressurised peas and beans as compared to untreated peas and beans. Reduction of phytic acid (max. 48%) and total phenolic acids (max. 78%) through cooking was greater than through pressurisation. Trypsin inhibitor activity decreased by up to 100% in peas and 84% in beans during pressurisation. Protein digestibility increased by up to 4.3% in peas when treated at 600 MPa and 60°C regardless of time and by 8.7% in beans treated at 600 MPa at 60°C for 60 min.
Effect of supplementary concentrate type on nitrogen partitioning in early lactation dairy cows offered perennial ryegrass-based pasture.
Whelan, S. J., Pierce, K. M., McCarney, C., Flynn, B. & Mulligan, F. J. (2012). Journal of Dairy Science, 95(8), 4468-4477.
Forty-four early lactation (64 ± 20 d in milk) dairy cows of mixed parity were used to assess the effect of 4 supplementary concentrate types (n = 11) on N partitioning. Animals were blocked on parity and calving date, and blocks were balanced for previous milk yield and milk protein yield. Cows received grazed pasture plus 5.17 kg of dry matter (DM)/d of one of the following isoenergetic concentrates: high crude protein (CP) with rolled barley (HP, 19% CP); low CP with rolled barley (LP, 15% CP); low CP with barley and supplementary 2-hydroxy-4-methylthio butanoic acid (HMBi; LP + HMBi, 15% CP); and low CP with ground corn (LP Corn, 15% CP). Nitrogen partitioning studies were conducted at wk 6 and 10 postpartum by using the n-alkane technique to determine pasture dry matter intake (DMI). Pasture DMI (13.3 kg of DM/d) and dietary digestibility of DM were not affected by concentrate type. Milk yield was lower for LP compared with other concentrate types (25.4 vs. 28.3 kg/d). Yields of milk protein and milk casein were not affected by concentrate type. However, milk solid yield and milk fat yield were higher for LP + HMBi (1.97 and 0.92 kg/d) compared with LP (1.72 and 0.87 kg/d). Concentrations of fat, protein, lactose, and casein were not affected by concentrate type. Dietary N intake was higher for HP compared with other treatments (0.545 vs. 0.482 kg/d, HP vs. average of the 3 LP treatments). Dietary N intakes were not different among low CP concentrates. Fecal N excretion was not affected by concentrate type. However, urinary N excretion was related to N intake and was higher for HP compared with other treatments (0.261 vs. 0.195 kg/d, HP vs. average of the 3 LP treatments). Urinary N excretion was not different among low CP concentrates. Milk N output was higher for HP (0.139 kg/d) compared with LP (0.12 kg/d) but not LP + HMBi (0.137 kg/d) or LP Corn (0.138 kg/d). The portion of feed N excreted as feces N was lower for HP compared with other treatments (0.272 vs. 0.327, HP vs. average of the 3 LP treatments. However, the portion of feed N excreted as urine N was higher for HP (0.466) compared with LP + HMBi (0.408) and LP Corn (0.366) but not compared with LP. The portion of feed N excreted as milk N was higher for LP Corn (0.282) compared with HP (0.257) but not LP + HMBi or LP. Dietary reformulation to reduce N excretion in pasture-based dairy production systems is possible. However, maintenance of milk yield and milk N when concentrate CP was reduced (19 vs. 15%) required the use of either protected AA (HMBi) or ground corn.
Brewer’s spent grain as a functional ingredient for breadsticks.
Ktenioudaki, A., Chaurin, V., Reis, S. F. & Gallagher, E. (2012). International Journal of Food Science & Technology, 47(8), 1765-1771.
Brewer’s spent grain (BSG) was evaluated for its potential as a functional baking ingredient. Scanning electron microscopy (SEM) was used to examine the microstructure of BSG and wheat ﬂours. Baked snacks (breadsticks) were prepared using 15%, 25% and 35% BSG and evaluated for their baking quality and ﬁbre and protein content (over a period of 3 months). The addition of BSG altered the baking characteristics of the breadsticks by aﬀecting their structure and texture. The snacks appeared to lack in cellular structure and crispiness. However, they had quite a stable shelf-life, as changes in texture, moisture and aW progressed at a low rate. Addition of 25% and 35% BSG signiﬁcantly increased the protein content of the snacks, and addition of 15% BSG more than doubled the content of dietary ﬁbre in the samples
Effect of forage source and a supplementary methionine hydroxy analog on nitrogen balance in lactating dairy cows offered a low crude protein diet.
Whelan, S. J., Mulligan, F. J., Flynn, B., McCarney, C. & Pierce, K. M. (2011). Journal of Dairy Science, 94(10), 5080-5089.
Four primiparous and 4 multiparous midlactation dairy cows were stratified by pre-experimental milk yield (23.5 ± 2.3 kg/d), protein yield (0.75 ± 0.066 kg/d), parity, and days in lactation (121 ± 10 d) into 4 groups of 2 in a 2 × 2 factorial, Latin square design (n = 8) to assess the effect of forage source and a supplementary methionine hydroxy analog on nitrogen (N) balance where low crude protein (CP) diets (13.3%) are offered. Diets contained either predominantly grass silage [GS (G− and G+)] or corn silage [CS (C− and C+)] as the forage source and were offered with (G+ and C+) or without (G− and C−) the isopropyl ester of 2-hydroxy-4 methylthio butanoic acid (HMBi). The G− and G+ contained 46% GS and 10% CS in the dry matter (DM), whereas C− and C+ contained 12% GS and 52% CS in the DM. Supplementary HMBi was included at a rate of 0.2% of DM in G+ and C+ diets. Diets were isonitrogenous (9.8 ± 0.4% protein truly digested in the small intestine) and isoenergetic (0.96 ± 0.01 units of energy for lactation; kg/DM). Each of the 4 experimental periods lasted 24 d: 14 d for dietary adaptation, followed by 10 d of housing in individual metabolism stalls; N balance was conducted on the last 5 d of each experimental period. Intake of DM was higher for CS-based vs. GS-based diets (20.23 vs. 18.41 kg/d). No effect of dietary treatment was found on milk yield or yields of milk fat, protein, and lactose. Supplementing with HMBi tended to improve milk solids yield (1.69 vs. 1.59 kg/d), casein yield (0.59 vs. 0.55 kg/d), and concentrations of casein (2.89 vs. 2.73%) and protein (3.58 vs. 3.49%) in the milk. Dietary N intake was higher for CS-based vs. GS-based diets (0.460 vs. 0.422 kg/d). However, forage source or supplementary HMBi had no effect on N excretion in the feces, urine, or milk. Excretion of urinary urea was positively related to N intake. Concentrations of urea N in the plasma (2.34 vs. 1.72 mmol/L), milk (2.54 vs. 2.24 mmol/L), and urine (123.32 vs. 88.79 mmol/L), and total excretion of urinary urea N (40.23 vs. 35.09 g/d) were higher for animals offered CS-based vs. GS-based diets. Corn silage improved N intake through improved DM intake. However, neither forage source nor HMBi supplementation affects N output in the feces, urine, or milk.
Analysis of ADP-glucose pyrophosphorylase expression during turion formation induced by abscisic acid in Spirodela polyrhiza (greater duckweed).
Wang, W. & Messing, J. (2012). BMC plant biology, 12(1), 5.
Background: Aquatic plants differ in their development from terrestrial plants in their morphology and physiology, but little is known about the molecular basis of the major phases of their life cycle. Interestingly, in place of seeds of terrestrial plants their dormant phase is represented by turions, which circumvents sexual reproduction. However, like seeds turions provide energy storage for starting the next growing season. Results: To begin a characterization of the transition from the growth to the dormant phase we used abscisic acid (ABA), a plant hormone, to induce controlled turion formation in Spirodela polyrhiza and investigated their differentiation from fronds, representing their growth phase, into turions with respect to morphological, ultra-structural characteristics, and starch content. Turions were rich in anthocyanin pigmentation and had a density that submerged them to the bottom of liquid medium. Transmission electron microscopy (TEM) of turions showed in comparison to fronds shrunken vacuoles, smaller intercellular space, and abundant starch granules surrounded by thylakoid membranes. Turions accumulated more than 60% starch in dry mass after two weeks of ABA treatment. To further understand the mechanism of the developmental switch from fronds to turions, we cloned and sequenced the genes of three large-subunit ADP-glucose pyrophosphorylases (APLs). All three putative protein and exon sequences were conserved, but the corresponding genomic sequences were extremely variable mainly due to the invasion of miniature inverted-repeat transposable elements (MITEs) into introns. A molecular three-dimensional model of the SpAPLs was consistent with their regulatory mechanism in the interaction with the substrate (ATP) and allosteric activator (3-PGA) to permit conformational changes of its structure. Gene expression analysis revealed that each gene was associated with distinct temporal expression during turion formation. APL2 and APL3 were highly expressed in earlier stages of turion development, while APL1 expression was reduced throughout turion development. Conclusions: These results suggest that the differential expression of APLs could be used to enhance energy flow from photosynthesis to storage of carbon in aquatic plants, making duckweeds a useful alternative biofuel feedstock.
Buckwheat starch: structure, functionality and enzyme in vitro susceptibility upon the roasting process.
Christa, K., Soral-Smietana, M. & Lewandowicz, G. (2009). International Journal of Food Sciences and Nutrition, 60(s4), 140-154.
Starch of dehulled buckwheat grains with a moisture content of 14.5% before and after thermal treatment (160°C/30 min) was used in this study. The crystal structure of buckwheat starch was of the A-type. The thermal process applied elicited slight changes both in infrared spectra and relative crystallinity on X-ray diffraction patterns. The scanning electron microscopy studies demonstrated polygonal and irregular shape of starch granules. After the thermal treatment, some breakings or conglomerates were noticed on the granules. The roasting process also affected a decrease in the swelling power and solubility. The release of glucose and changes in resistant starch after partial hydrolysis by pancreatic α-amylase and other intestinal enzymes were analysed as well. The scanning electron microscopy visualization indicated significant susceptibility of buckwheat starch at the beginning (0.5 h) and during 6 h in vitro amylolysis.
Deficiency of maize starch-branching enzyme i results in altered starch fine structure, decreased digestibility and reduced coleoptile growth during germination.
Xia, H., Yandeau-Nelson, M., Thompson, D. B. & Guiltinan, M. J. (2011). BMC Plant Biology, 11(1), 95-107.
Background: Two distinct starch branching enzyme (SBE) isoforms predate the divergence of monocots and dicots and have been conserved in plants since then. This strongly suggests that both SBEI and SBEII provide unique selective advantages to plants. However, no phenotype for the SBEI mutation, sbe1a, had been previously observed. To explore this incongruity the objective of the present work was to characterize functional and molecular phenotypes of both sbe1a and wild-type (Wt) in the W64A maize inbred line. Results: Endosperm starch granules from the sbe1a mutant were more resistant to digestion by pancreatic α-amylase, and the sbe1a mutant starch had an altered branching pattern for amylopectin and amylose. When kernels were germinated, the sbe1a mutant was associated with shorter coleoptile length and higher residual starch content, suggesting that less efficient starch utilization may have impaired growth during germination. Conclusions: The present report documents for the first time a molecular phenotype due to the absence of SBEI, and suggests strongly that it is associated with altered physiological function of the starch in vivo. We believe that these results provide a plausible rationale for the conservation of SBEI in plants in both monocots and dicots, as greater seedling vigor would provide an important survival advantage when resources are limited.
Profiling brewers' spent grain for composition and microbial ecology at the site of production.
Robertson, J. A., I'Anson, K. J. A., Treimo, J., Faulds, C. B., Brocklehurst, T. F., Eijsink, V. G. H. & Waldron, K. W. (2010). LWT-Food Science and Technology, 43(6), 890-896.
Brewers' spent grain (BSG) is a readily available, high volume low cost byproduct of brewing and is a potentially valuable resource for industrial exploitation. The variation in BSG composition and the implications for microbiological spoilage by a resident microflora might affect the potential to use BSG as a reliable food-grade industrial feedstock for value-added downstream processing. Fresh samples of BSG from a range of 10 breweries have been analysed for their microbial and chemical composition. The results show that a resident microflora of mainly thermophilic aerobic bacteria (<107 g-1 fresh weight) persists on BSG. This population is susceptible to rapid change but at the point of production BSG can be considered microbiologically stable. Chemically, BSG is rich in polysaccharides, protein and lignin. Residual starch can contribute up to 13% of the dry weight and BSG from lager malts has higher protein content than that from ale. In general, at the point of production, BSG is a relatively uniform chemical feedstock available for industrial upgrading. Differences between breweries should not present problems when considering BSG for industrial exploitation but susceptibility to microbial colonisation is identified as a potential problem area which might restrict its successful exploitation.
Enzymatic solubilization of brewers’ spent grain by combined action of carbohydrases and peptidases.
Treimo, J., Westereng, B., Horn, S. J., Forssell, P., Robertson, J. A., Faulds, C. B., Waldron K. W., Buchert J. & Eijsink, V. G. (2009). Journal of Agricultural and Food Chemistry, 57(8), 3316-3324.
Brewers’ spent grain (BSG), a high-volume coproduct from the brewing industry, primarily contains proteins, barley cell wall carbohydrates, and lignin. To create new possibilities for the exploitation of this large biomass stream, the solubilization of BSG by the combined action of carbohydrases (Depol 740 and Econase) and peptidase (Alcalase and Promod 439) was explored. Hydrolysis protocols were optimized with respect to temperature (influencing both microbial contamination and rate of enzymatic hydrolysis), pH, enzyme dose, order of enzyme addition, and processing time. On the basis of this approach, one- and two-step protocols are proposed taking 4−8 h and yielding combined or separate fractions of hydrolyzed oligosaccharides and liberated hydrolyzed protein. Optimized procedures resulted in the solubilization of >80% of the proteinaceous material, up to 39% of the total carbohydrates, and up to 42% of total dry matter in BSG. Of the original xylan present in BSG, 36% could be solubilized. Sequential and simultaneous treatments with the two enzyme types gave similar results. In sequential processes, the order of the carbohydrase and peptidase treatments had only minor effects on the outcome. Depol 740 released more pentoses than Econase and gave slightly higher overall dry matter solubilization yields.
Effect of sorghum flour addition on in vitro starch digestibility, cooking quality, and consumer acceptability of durum wheat pasta.
Khan, I., Yousif, A. M., Johnson, S. K. & Gamlath, S. (2014). Journal of Food Science, 79(8), S1560-S1567.
Whole grain sorghum is a valuable source of resistant starch and polyphenolic antioxidants and its addition into staple food like pasta may reduce the starch digestibility. However, incorporating nondurum wheat materials into pasta provides a challenge in terms of maintaining cooking quality and consumer acceptability. Pasta was prepared from 100% durum wheat semolina (DWS) as control or by replacing DWS with either wholegrain red sorghum flour (RSF) or white sorghum flour (WSF) each at 20%, 30%, and 40% incorporation levels, following a laboratory-scale procedure. Pasta samples were evaluated for proximate composition, in vitro starch digestibility, cooking quality, and consumer acceptability. The addition of both RSF and WSF lowered the extent of in vitro starch digestion at all substitution levels compared to the control pasta. The rapidly digestible starch was lowered in all the sorghum-containing pastas compared to the control pasta. Neither RSF or WSF addition affected the pasta quality attributes (water absorption, swelling index, dry matter, adhesiveness, cohesiveness, and springiness), except color and hardness which were negatively affected. Consumer sensory results indicated that pasta samples containing 20% and 30% RSF or WSF had acceptable palatability based on meeting one or both of the preset acceptability criteria. It is concluded that the addition of wholegrain sorghum flour to pasta at 30% incorporation level is possible to reduce starch digestibility, while maintaining adequate cooking quality and consumer acceptability.
Physicochemical properties of starch from sago (metroxylon sagu) palm grown in mineral soil at different growth stages.
Uthumporn, U., Wahidah, N. & Karim, A. A. (2014). IOP Conference Series: Materials Science and Engineering (Vol. 62, No. 1, p. 012026). IOP Publishing.
A study was carried out to determine the physico-chemical properties of sago starch from sago palm grown in mineral soil at different growth stages. Four stages of sago palm, namely, Plawei (P), Bubul (B), Angau Muda (AM) and Angau Tua (AT) were studied. Sago starch granules were observed by using scanning electron microscopy (SEM) while the x-ray diffraction patterns were examined to study the starch crystallinity. The highest starch content was found at Plawei stage (94.2%) and Angau Muda stage (97.9%), respectively. The amylose content varied between 29.4 to 31.2% for each growth stages. The highest swelling power was found at the earliest growth stages (P) late growth stages (AT) which are 13.3 g/g and 13.2 g/g, respectively. Granule size distributions were similar as the palm grows to the later growth stages, where highest mean diameter of sago starches granules was found at AM. Variation of starch, amylose and proximate content was observed for starches derived from sago palm different growth stages were insignificant.