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%.
Two issues in dietary fiber measurement.
McCleary, B. V. (2001). Cereal Foods World, 46(4), 164-165.
Enzyme activity and purity of these topics, the easiest to deal with is the importance of enzyme purity and activity. As a scientist actively involved in polysaccharide research over the past 25 years, I have come to appreciate the importance of enzyme purity and specificity in polysaccharide modification and measurement (7). These factors translate directly to dietary fiber (DF) methodology, because the major components of DF are carbohydrate polymers and oligomers. The committee report published in the March issue of Cereal FOODS WORLD refers only to the methodology for measuring enzyme purity and activity (8) that led up the AOAC method 985.29 (2). In this work enzyme purity was gauged by the lack of hydrolysis (i.e., complete recovery) of a particular DF component (e.g. β-glucan, larch galactan or citrus pectin). Enzyme activity was measured by the ability to completely hydrolyze representative starch and protein (namely wheat starch and casein). These requirements and restrictions on enzyme purity and activity were adequate at the time the method was initially developed and served as a useful working guide. However, it was recognized that there was a need for more stringent quality definitions and assay procedures for enzymes used in DF measurements.
Measurement of resistant starch.
McCleary, B. V. & Monaghan, D. A. (2002). Journal of AOAC International, 85(3), 665-675.
A robust and reliable method was developed to measure resistant starch (RS), i.e., starch that enters the large intestine. In vivo conditions were reflected as much as possible while a user-friendly format was maintained. Parameters investigated included α-amylase concentration, pH of incubation, maltose inhibition of α-amylase, the need for amyloglucosidase inclusion, the effect of shaking and stirring on determined values, and problems in recovering and analyzing the RS-containing pellet. The RS values obtained were in good agreement with published in vivo data. An interlaboratory evaluation of the method has been completed (First Action Method 2002.02).
Measurement of resistant starch by enzymatic digestion in starch and selected plant materials: Collaborative study.
McCleary, B. V., McNally, M. & Rossiter, P. (2002). Journal of AOAC International, 85(5), 1103-1111.
Interlaboratory performance statistics was determined for a method developed to measure the resistant starch (RS) content of selected plant food products and a range of commercial starch samples. Food materials examined contained RS (cooked kidney beans, green banana, and corn flakes) and commercial starches, most of which naturally contain, or were processed to yield, elevated RS levels. The method evaluated was optimized to yield RS values in agreement with those reported for in vivo studies. Thirty-seven laboratories tested 8 pairs of blind duplicate starch or plant material samples with RS values between 0.6 (regular maize starch) and 64% (fresh weight basis). For matrixes excluding regular maize starch, repeatability relative standard deviation (RSDr) values ranged from 1.97 to 4.2%, and reproducibility relative standard deviation (RSDR) values ranged from 4.58 to 10.9%. The range of applicability of the test is 2-64% RS. The method is not suitable for products with <1% RS (e.g., regular maize starch; 0.6% RS). For such products, RSDr and RSDR values are unacceptably high.
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.
An integrated procedure for the measurement of total dietary fibre (including resistant starch), non-digestible oligosaccharides and available carbohydrates.
McCleary, B. V. (2007). Analytical and Bioanalytical Chemistry, 389(1), 291-308.
A method is described for the measurement of dietary fibre, including resistant starch (RS), non-digestible oligosaccharides (NDO) and available carbohydrates. Basically, the sample is incubated with pancreatic α-amylase and amyloglucosidase under conditions very similar to those described in AOAC Official Method 2002.02 (RS). Reaction is terminated and high molecular weight resistant polysaccharides are precipitated from solution with alcohol and recovered by filtration. Recovery of RS (for most RS sources) is in line with published data from ileostomy studies. The aqueous ethanol extract is concentrated, desalted and analysed for NDO by high-performance liquid chromatography by a method similar to that described by Okuma (AOAC Method 2001.03), except that for logistical reasons, D-sorbitol is used as the internal standard in place of glycerol. Available carbohydrates, defined as D-glucose, D-fructose, sucrose, the D-glucose component of lactose, maltodextrins and non-resistant starch, are measured as D-glucose plus D-fructose in the sample after hydrolysis of oligosaccharides with a mixture of sucrase/maltase plus β-galactosidase.
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.
Improvement of the AOAC 2009.01 total dietary fibre method for bread and other high starch containing matrices.
Brunt, K. & Sanders, P. (2013). Food Chemistry, 140(3), 574-580.
The dietary fibre (DF) content in wheat grain based food products have been established with both the classical AOAC 985.29 dietary fibre and the new AOAC 2009.01 total dietary fibre protocol. There is a good agreement between the high molecular weight dietary fibre (HMWDF) contents measured with the AOAC 2009.01 method and (DF) content measured with the classical AOAC 985.29 method in wheat grain based food products. With the AOAC 2009.01 method also a significant amount of low molar weight dietary fibre (LMWDF), ranging from 1% to 3% w/w, was measured which is not quantified with the AOAC 985.29 method. With semi-preparative GPC the LMWDF (DP ≥ 3) fractions in the wheat grain based food products were isolated. The monosaccharide composition of the dissolved LMWDF constituents was determined. Glucose was by far the most abundant monosaccharide present with arabinose, galactose, xylose and mannose as minor constituents. It appeared that the LMWDF contains still not fully converted digestible starch/malto-oligosaccharide fragments with DP ≥ 3, which are erroneously quantified as LMWDF. By introducing an extra AMG hydrolysis step in the AOAC 2009.01 protocol after evaporation of the ethanol and dissolving the residue in deionised water, these malto-oligosaccharides are fully hydrolysed resulting in that way in a correct and lower LMWDF content.
Sterilization in a liquid of a specific starch makes it slowly digestible in vitro and low glycemic in rats.
Severijnen, C., Abrahamse, E., Van der Beek, E. M., Buco, A., van de Heijning, B. J. M., van Laere, K. & Bouritius, H. (2007). The Journal of Nutrition, 137(10), 2202-2207.
Diabetics are recommended to eat a balanced diet containing normal amounts of carbohydrates, preferably those with a low glycemic index. For solid foods, this can be achieved by choosing whole-grain, fiber-rich products. For (sterilized) liquid products, such as meal replacers, the choices for carbohydrate sources are restricted due to technological limitations. Starches usually have a high glycemic index after sterilization in liquids, whereas low glycemic sugars and sugar replacers can only be used in limited amounts. Using an in vitro digestion assay, we identified a resistant starch (RS) source [modified high amylose starch (mHAS)] that might enable the production of a sterilized liquid product with a low glycemic index. Heating mHAS for 4–5 min in liquid increased the slowly digestible starch (SDS) fraction at the expense of the RS portion. The effect was temperature dependent and reached its maximum above 120°C. Heating at 130°C significantly reduced the RS fraction from 49 to 22%. The product remained stable for at least several months when stored at 4°C. To investigate whether a higher SDS fraction would result in a lower postprandial glycemic response, the sterilized mHAS solution was compared with rapidly digestible maltodextrin. Male Wistar rats received an i.g. bolus of 2.0 g available carbohydrate/kg body weight. Ingestion of heat-treated mHAS resulted in a significant attenuation of the postprandial plasma glucose and insulin responses compared with maltodextrin. mHAS appears to be a starch source which, after sterilization in a liquid product, acquires slow-release properties. The long-term stability of mHAS solutions indicates that this may provide a suitable carbohydrate source for low glycemic index liquid products for inclusion in a diabetes-specific diet.
Effects of wheat inclusion and xylanase supplementation of the diet on productive performance, nutrient retention, and endogenous intestinal enzyme activity of laying hens.
Mirzaie, S., Zaghari, M., Aminzadeh, S., Shivazad, M. & Mateos, G. G. (2012). Poultry Science, 91(2), 413-425.
An experiment was conducted to study the effects of inclusion of a wheat cultivar (high in nonstarch polysaccharides) and xylanase supplementation of the diet on productive performance, pH of the gastrointestinal tract, nutrient retention, and intestinal enzyme activity of Hy-Line W-36 laying hens from 25 to 47 wk of age. The experiment was completely randomized with 8 treatments arranged factorially with 4 levels of wheat (0, 23, 46, and 69%) that corresponded to a dietary arabinoxylan content of 3.0, 3.3, 3.6, and 3.9%, with or without xylanase supplementation. Each treatment was replicated 5 times. For the entire experimental period, egg weight (P < 0.05) and egg mass (P < 0.01) were reduced and the feed conversion ratio was hindered (P < 0.05) with increased levels of wheat in the diet, but ADFI and egg production were not affected. Xylanase supplementation improved egg production (P < 0.05), egg mass (P < 0.01), and the feed conversion ratio (P < 0.01). Diet did not affect egg quality at any age, except for shell thickness at 47 wk that was improved with xylanase supplementation (P < 0.05). Digesta pH of the different organs of the gastrointestinal tract was not affected by wheat inclusion or xylanase supplementation. Ileal viscosity increased (P < 0.001) with wheat inclusion and decreased (P < 0.001) with xylanase supplementation at all ages. Fat digestibility (P < 0.001) decreased with increased levels of wheat but AMEn content of the diets (P < 0.05) and nitrogen retention were not affected. Wheat inclusion increased (P < 0.001) amylase (33 wk), lipase (33 wk), and aminopeptidase (47 wk) activity in the duodenum as well as lipase activity in the jejunum at 47 wk of age. However, xylanase supplementation did not affect the activity of any of the enzymes studied. It is concluded that most of the negative effects of wheat inclusion in the diet were reduced or even disappeared with xylanase supplementation. Wheat with a high nonstarch polysaccharide content (Pishtaz cultivar) can be used at levels of up to 69% in laying-hen diets without negatively affecting bird performance, provided that feeds are supplemented with xylanase.
Exotic corn lines with increased resistant starch and impact on starch thermal characteristics.
Rohlfing, K. A., Pollak, L. M. & White, P. J. (2010). Cereal Chemistry, 87(3), 190-193.
Ten parent corn lines, including four mutants (dull sugary2, amylose-extender sugary2, amylose-extender dull, and an amylose-extender with introgressed Guatemalen germplasm [GUATae]) and six lines with introgressed exotic germplasm backgrounds, were crossed with each other to create 20 progeny crosses to increase resistant starch (RS) as a dietary fiber in corn starch and to provide materials for thermal evaluation. The resistant starch 2 (RS2) values from the 10 parent lines were 18.3–52.2% and the values from the 20 progeny crosses were 16.6–34.0%. The %RS2 of parents was not additive in the offspring but greater RS2 in parents was correlated to greater RS2 in the progeny crosses (r = 0.63). Differential scanning calorimetry (DSC) measured starch thermal characteristics, revealing positive correlations of peak gelatinization temperature and change in enthalpy with %RS2 (r = 0.65 and r = 0.67, P ≤ 0.05); however, % retrogradation (a measure of RS3) and retrogradation parameters did not correlate with %RS2. The %RS2 and onset temperature increased with the addition of the ae gene, likely because RS delays gelatinization.
Effect of extrusion conditions on resistant starch formation from pastry wheat flour.
Kim, J. H., Tanhehco, E. J. & Ng, P. K. W. (2006). Food Chemistry, 99(4), 718-723.
Pastry wheat flour was extruded under various conditions of feed moisture (20%, 40%, and 60%) and screw speed (150, 200, and 250 rpm), at constant barrel temperature profile (40, 60, 80, 100, and 120°C, feed port to exit die). The extruded samples were stored at 4°C for 0, 7, or 14 days, at which times resistant starch (RS) formation was analyzed. Thermal and pasting properties of extruded samples stored for 14 days were analyzed using a differential scanning calorimeter and rapid visco analyzer (RVA), respectively. The RS content increased after extrusion compared to non-extruded pastry wheat flour. High significant positive correlations of feed moisture (P < 0.01) and storage period (P < 0.05) with RS formation were observed. The RS derived from extrusion and storage showed higher thermal stability with decreasing feed moisture and screw speed. Statistically significant differences in pasting properties were observed with feed moisture or screw speed. In particular, the setback value from RVA of the sample was significantly increased with increasing feed moisture. These results indicate that feed moisture and storage time were both important factors for the formation of RS from pastry wheat flour during extrusion.
Resistant starch and starch pasting properties of a starch synthase IIa-deficient wheat with apparent high amylose.
Yamamori, M., Kato, M., Yui, M. & Kawasaki, M. (2006). Australian Journal of Agricultural Research, 57(5), 531-535.
The bread wheat (Triticum aestivum L.) analysed in this study has been produced by genetically eliminating the starch synthase IIa and shows apparent high amylose (HA) in the flour starch. Some starch properties of the HA wheat were analysed. The HA wheat contained 2.8–3.6% resistant starch (RS), much more than the normal (control) wheat, which contained almost no RS. Autoclaving the HA and normal wheat starches increased RS. The former contained 10.5% RS and the latter 5.9 or 6.8% RS. Swelling of the HA wheat starch and its pasting properties using Rapid ViscoAnalyzer (RVA) were investigated. Swelling power (g/g) of the HA wheat in 0.1% AgNO3 and swelling volume (mL/g) in urea solution were significantly less than those of the normal wheat. The RVA profile of the HA wholemeal and starch also differed from the normal. The peak viscosity, minimum viscosity, and final viscosity of HA were low, and breakdown (peak minus minimum viscosity) was very small. These findings show that amount of resistant starch and pasting properties are unique in the HA wheat starch, probably caused by lack of starch synthase IIa.
Effects of process variables and addition of polydextrose and whey protein isolate on the properties of barley extrudates.
Kirjoranta, S., Solala, K., Suuronen, J. P., Penttilä, P., Peura, M., Serimaa, R., Tenkanen, M. & Jouppila, K. (2012). International Journal of Food Science & Technology, 47(6), 1165-1175.
Extrusion cooking is commonly used in the production of snacks. In the present study, extrudates were prepared using barley flour alone and with the addition of either polydextrose (PD) or whey protein isolate (WPI) and both PD and WPI. Independent process variables were water content of the mass (17%, 20% and 23%), screw speed (200, 350 and 500 rpm) and temperature of section 6 and die (110, 130 and 150°C). Expansion, hardness, water content, porosity and chemical composition of the extrudates were analysed. Highly porous and expanded snack products with high dietary fibre and protein contents were obtained from barley flour and WPI when water content of mass was 17%, screw speed 500 rpm and temperature of section 6 and die 130°C. Barley flour alone or with PD resulted in hard and non-expanded extrudates. Expansion of extrudates was statistically significantly increased with decreasing water content of the mass and increasing screw speed in all trials.
Elimination of resistant starch type II within the framework of total starch and dietary fibre analysis by microwave irradiation.
Themeier, H., Hollmann, J., Neese, U. & Lindhauer, M. G. (2010). Quality Assurance and Safety of Crops & Foods, 2(1), 46-51.
Introduction The presence of resistant starch in samples containing non-starch polysaccharides has always been a challenge to enzymatic total starch and total fibre analysis. Objective and methods Based on microwave-induced pressure disintegration technique the Association of Official Analytical Chemists methods for the determination of total starch (AOAC 996.11) and total dietary fibre (AOAC 991.43) have been modified to completely eliminate undesirable resistant starch fractions with respect to digestion procedures using thermostable α-amylase and amyloglucosidase. Results Microwave treatment of high-amylose starch samples resulted in excellent total starch recovery in the Association of Official Analytical Chemists standard method no. 996.11. After integration of microwave disintegration technique into the total dietary fibre method AOAC 911.43 irradiation experiments with different model mixtures consisting of non-starch polysaccharides components and high-amylose starch fractions resulted in the complete elimination of undesirable resistant starch fractions. Conclusion Therefore the microwave technique can be a very efficient means for the elimination of resistant starch and provides more realistic values in analytical total dietary fibre procedures with respect to samples containing critical enzyme resistant starches.
Resistant starch in Micronesian banana cultivars offers health benefits.
Thakorlal, J., Perera, C. O., Smith, B., Englberger, L. & Lorens, A. (2010). Pacific Health Dialog, 16(1), 49-59.
Resistant Starch (RS) is a type of starch that is resistant to starch hydrolyzing enzymes in the stomach and thus behaves more like dietary ﬁbre. RS has been shown to have beneﬁcial effects in disease prevention including modulation of glycaemic index diabetes, cholesterol lowering capability and weight management, which are critically important for many people in the Federated States of Micronesia. Green bananas are known to contain substantial concentrations of RS and are a common part of the Micronesian diet. Therefore the aim of this study was to determine the RS content in banana cultivars from Pohnpei, Micronesia: Daiwang, Inahsio, Karat, Utin Kerenis and Utin Ruk, for which no such information was available. Utin Kerenis, Inahsio and Utin Ruk were found to contain the highest amounts of RS. The fate of RS after incorporation into a food product (i.e.. pancakes) was also studied and a signiﬁcant reduction in the RS content was found for each cultivar after cooking. Microscopy of the banana samples indicated that the overall morphology of the cultivars was similar. In conclusion, green banana, including these varieties, should be promoted in Micronesia and other places for their rich RS content and related health beneﬁts including diabetes control. Further research is needed to more clearly determine the effects of cooking and food processing on RS.
Enzyme susceptibility of high-amylose starch precipitated from sodium hydroxide dispersions.
Evans, A. & Thompson, D. B. (2008). Cereal Chemistry, 85(4), 480-487.
Type III resistant starch (RS) is understood to be due to the ordered structure formation in the process of retrogradation. Most treatments of granular high-amylose maize starch (HAMS) do not completely eliminate the original ordered structure. We hypothesized that residual ordered structure would constrain subsequent physical reassociation of chains and the formation of RS. The objective was to generate differences in enzyme susceptibility using two means of precipitation of fully dispersed starch and to relate differences in enzyme susceptibility to the structure of the precipitates. Dispersions in sodium hydroxide were precipitated either with ethanol or ammonium sulfate. RS and the timecourse of digestion were determined. Crystallinity and helicity were estimated using wide-angle X-ray diffraction and solid-state 13C CP/MAS NMR, respectively. Precipitation of whole starch with ethanol led to lower RS values (≈24%) than precipitation with ammonium sulfate (≈39%) and also to higher reaction rate constants for an early component of digestion. Ethanol precipitation of a branched starch fraction gave essentially no RS, whereas ammonium sulfate precipitation of the same branched material had >20% RS. Ethanol precipitates contained single helices, in most but not all cases, contributing to V-type crystallinity. Ammonium sulfate precipitates had double helices contributing to B-type crystallinity.
In vitro fermentation of spent turmeric powder with a mixed culture of pig faecal bacteria.
Han, K. H., Azuma, S. & Fukushima, M. (2014). Food & Function, 10, 2446-2452.
The fermentation potential of spent turmeric was studied in in vitro swine faecal batch cultures. The spent turmeric residue (the enzyme-resistant fraction from spent turmeric, EST) was obtained through the use of the digestive enzymes amyloglucosidase and pancreatin and compared to cellulose and high-amylose starch (HAS) as carbon sources. EST showed significant increases in total anaerobes, bifidobacteria, lactobacilli and lactic acid bacteria populations compared to cellulose at 12, 24 and 48 h, and the total anaerobic level in the HAS group was significantly higher than in the cellulose group at 24 and 48 h. However, a significant decrease in the coliform population was only found in the HAS group compared to the cellulose group at 48 h. The total short-chain fatty acid (SCFA) concentrations in the EST and HAS groups were significantly higher than that in the cellulose group at 12 h and 48h. However, there was no significant difference in the total SCFA concentration between the EST and HAS groups at 12 h and 48h. Ammonia and pH levels in the EST and HAS groups were significantly lower than those in the cellulose group at 24 and 48 h, but there was no significant difference between the EST and HAS groups. These results indicate that the fermentation potential of the enzyme-resistant fraction from spent turmeric is comparable to that of commercially established resistant starch.
Impact of ancient cereals, pseudocereals and legumes on starch hydrolysis and antiradical activity of technologically viable blended breads.
Collar, C., Jiménez, T., Conte, P. & Fadda, C. (2014). Carbohydrate Polymers, 113, 149-158.
Wheat flour replacement from 22.5% up to 45% by incorporation of ternary blends of teff (T), green pea (GP) and buckwheat (BW) flours provided technologically viable and acceptable sensory rated multigrain breads with superior nutritional value compared to the 100% wheat flour (WT) counterparts. Blended breads exhibited superior nutritional composition, larger amounts of bioaccessible polyphenols, higher anti-radical activity, and lower and slower starch digestibility. Simultaneous lower rapidly digestible starch (57.1%) and higher slowly digestible starch (12.9%) and resistant starch (2.8%) contents (g per 100 g fresh bread), considered suitable nutritional trends for dietary starch fractions, were met by the blend formulated 7.5% T, 15% GP, 15% BK. The associated mixture that replaced 37.5% WT, showed a rather lower extent and slower rate of starch hydrolysis with medium-low values for C∞, and H90, and lowest k, and intermediate expected Glycaemic Index (86). All multigrain breads can be labelled as source of dietary fibre (≥3 g dietary fibre/100 g bread).
Characterization and Prebiotic Effect of the Resistant Starch from Purple Sweet Potato.
Zheng, Y., Wang, Q., Li, B., Lin, L., Tundis, R., Loizzo, M. R., Zheng, B. & Xiao, J. (2016). Molecules, 21(7), 932.
Purple sweet potato starch is a potential resource for resistant starch production. The effects of heat-moisture treatment (HMT) and enzyme debranching combined heat-moisture treatment (EHMT) on the morphological, crystallinity and thermal properties of PSP starches were investigated. The results indicated that, after HMT or EHMT treatments, native starch granules with smooth surface was destroyed to form a more compact, irregular and sheet-like structure. The crystalline pattern was transformed from C-type to B-type with decreasing relative crystallinity. Due to stronger crystallites formed in modified starches, the swelling power and solubility of HMT and EHMT starch were decreased, while the transition temperatures and gelatinization enthalpy were significantly increased. In addition, HMT and EHMT exhibited greater effects on the proliferation of bifidobacteria compared with either glucose or high amylose maize starch.
Metabolomic and transcriptomic responses induced in the livers of pigs by the long-term intake of resistant starch.
Sun, Y., Yu, K., Zhou, L., Fang, L., Su, Y. & Zhu, W. (2016). Journal of animal science, 94(3), 1083-1094.
The present study investigated metabolomic and transcriptomic responses in the livers of pigs to evaluate the effects of resistant starch on the body’s metabolism at the extraintestinal level. Thirty-six Duroc× Landrace × Large White growing barrows (70 d of age) were randomly allocated to either the corn starch (CS) group or the raw potato starch (RPS) group with a randomized complete block design; each group consisted of 6 replicates (pens), with 3 pigs per pen. Pigs in the CS group were offered a corn–soybean–based diet, whereas pigs in the RPS group were put on a diet in which 230 (growing) or 280 g/kg (finishing) purified CS was replaced with purified RPS during a 100-d trial. The livers of pigs were collected for metabolome and gene expression analysis. Gas chromatography–mass spectrometry analysis showed that compared with the CS diet, the RPS diet decreased (P < 0.05) cholesterol and palmitic acid as well as increased (P < 0.05) 3-hydroxybutyric acid, which indicated the reduction of adipose weight and fatty acid biosynthesis and the elevation of fatty acid Β-oxidation. In addition, 2-ketoglutaric acid and glucose-6-phosphate were increased (P < 0.05) although pyruvic acid was decreased (P < 0.05) in the RPS group, indicating the upregulated capacity of glucose phosphorylation and glycolysis. Microarray analysis showed that the mRNA expression of transmembrane glycoprotein cluster of differentiation 36 (CD36), carnitine palmitoyltransferase 1B (CPT1B), and medium-chain acyl-CoA dehydrogenase (ACADM) were downregulated (P < 0.05) whereas 1-acylglycerol-3-phosphate O-acyltransferase 4 (AGPAT4), glycerol-3-phosphate acyltransferase (GPAT), and fatty acid binding protein 1 (FABP1) were upregulated (P < 0.05) in the RPS diet, indicating a decrease in fatty acid intake and synthesis and an increase in fatty acid oxidation and glycerophospholipid synthesis. The results demonstrated that the long-term consumption of RPS could modulate hepatic lipid metabolism by decreasing fatty acid synthesis as well as increasing lipid oxidation and glycerophospholipid synthesis.