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PubMed2002

Final report on the safety assessment of aluminum starch octenylsuccinate.

Aluminum Starch Octenylsuccinate is the aluminum salt of the reaction product of octenylsuccinic anhydride with starch. It is used in cosmetics at concentrations as high as 30% as an anticaking agent and a nonaqueous viscosity increasing agent. No information was available on the presence of impurities in the cosmetic-grade ingredient. When used in foods, Aluminum Starch Octenylsuccinate is identified as a modified food starch, and is subject to limitations on heavy metal residues. Oral studies using Aluminum Starch Octenylsuccinate or its related sodium salt produced no adverse systemic, reproductive, or developmental effects. Dermal injections produced no abnormal skin or systemic reactions in guinea pigs. Ocular toxicity was assessed in rabbits and using an in vitro test (chorioallantoic membrane vascular assay). In both cases no toxicity was seen. An acute inhalation toxicity study in rats was negative. Clinical tests indicated little irritation potential and no sensitization. Absent data on impurities in cosmetic-grade material, it was determined that such material should meet the same impurities requirements established for modified food starches. Based on these available data the Cosmetic Ingredient Review Expert Panel concluded that Aluminum Starch Octenylsuccinate is safe as used in cosmetic formulations provided that established limitations imposed on heavy metal concentrations are not exceeded.

Aluminum↗
PubMed1995

Influence of the physical form of barley grain on the digestion of its starch in the human small intestine and implications for health.

It has been suggested that incomplete digestion of cereal starch explains the low energy values of certain cereals of large particle size. We used human subjects with ileostomies to investigate the digestion of barley and to determine whether the physical form of barley affects stomal excretion of starch, glucooligosaccharides, nitrogen, fat, and calculated energy. Only 2 +/- 1% of starch remained undigested after finely milled barley was eaten, but after flaked barley was eaten 17 +/- 1% resisted digestion, partly as oligosaccharides (G1-G10) but largely as intact unpitted starch granules bound by intact cell walls. The calculated energy excretion from the stoma was three times higher after flaked than after milled barley [51.5 decreasing to 15.3 kJ/g nonstarch polysaccharide (NSP, P < 0.001]. NSP, starch, and fat made almost equal contributions to the higher energy excretion. It is concluded that possibly the botanical source of cereals and certainly processing, other than retrogradation of the starch, are important determinants of starch digestibility and energy value. Possible clinical implications are introduced.

Adult↗
PubMed1998

Apparent digestibility of a debranched amylopectin-lipid complex and resistant starch incorporated into enteral formulas fed to ileal-cannulated dogs1.

The purpose of this study was to evaluate apparent digestibility in ileal-cannulated dogs fed enteral diets containing a debranched amylopectin-lipid complex (V-complex) or resistant starch. Six ileal-cannulated dogs were randomized into a replicated 3 x 3 Latin square design for determination of digestibility of three experimental treatments. Dietary treatments were as follows: 1) control; 2) V-complex; and 3) resistant starch. Diets were similar in chemical composition. Apparent digestibility of dry matter (DM), organic matter (OM) and carbohydrate by dogs fed the control diet was higher (P < 0.05) than for dogs consuming the other diets. Mean apparent digestibilities of carbohydrate for the control, V-complex and resistant starch diets were 89, 76 and 43%, respectively. Both DM and carbohydrate digestibility were lower (P < 0.05) for resistant starch compared with V-complex. Fecal dry and wet weights for dogs fed the control diet were lower (P < 0.05) than for those receiving either the resistant starch or V-complex treatments. Dogs fed the V-complex diet produced approximately 90 g less feces per day than dogs fed resistant starch. Dietary incorporation of V-complex to replace traditional carbohydrates may be beneficial for diabetic patients because of the decreased digestibility and subsequent glucose absorption rate. Furthermore, incorporation of resistant starch into enteral formulas may improve gastrointestinal tract health status as a result of increased fecal bulk, potential dilution of toxins in the intestinal lumen and greater production of short-chain fatty acids.

Amylopectin↗
PubMed2005

Evolution and expression analysis of starch synthase III and IV in rice.

Plants contain at least five subfamilies of starch synthases, granule bound starch synthase (GBSS) and starch synthases I, II, III, and IV (SSI, SSII, SSIII, SSIV). In this work, two members of SSIII and SSIV, respectively, were cloned and designated OsSSIII-1/-2 and OsSSIV-1/-2 in rice. Together with six other previously reported genes, the SS gene family in rice therefore is known to be duplicated and to comprise ten SS genes distributed among the five subfamilies. The starch synthase activity of each SS was confirmed by expression and enzyme activity assay in E. coli. Expression profile analysis with reverse transcription-PCR, western blotting and zymogram, indicates that OsSSIII-2 and OsSSIV-1 are mainly expressed in endosperm, while OsSSIII-1 and OsSSIV-2 are mainly expressed in the leaves. With a similar pattern of genes encoding other enzymes for starch synthesis, (such as GBSS, SSII, ADP-glucose pyrophosphorylases, and branching enzymes), it is suggested that two divergent groups of these genes should be classified in rice. Group I genes are preferentially expressed in the endosperm and function on storage starch synthesis. Group II genes are mainly expressed in leaves and some of them in the early developing endosperm, and function on transient starch synthesis in rice.

Amino Acid Sequence↗
PubMed2005

Effects of regular and modified starches on cooked pale, soft, and exudative; normal; and dry, firm, and dark breast meat batters.

The effects of potato and tapioca starches (regular and modified) on the texture, yield, and microstructure of pale, soft, and exudative (PSE); normal; and dark, firm, and dry (DFD) chicken breast meats were studied. Cook yield and fracture force were higher in DFD than in normal and PSE meat. All starches significantly improved yield with modified tapioca showing the best results. Light microscopy showed even distribution and gelatinization of large potato starch granules and small tapioca granules. Addition of starches to the normal meat (46 < L* < 53, 5.9 < pH < 6.1) resulted in higher modulus of rigidity (G') values above 60 degrees C. During cooling, this trend continued as all starches provided significantly higher G' values compared with the control; regular and modified potato resulted in higher G' values than the tapioca starches. Overall, starch addition can compensate for part of the meat protein functionality lost in PSE meat.

Animals↗
PubMed1998

Rice-starch oral rehydration therapy in neonates and young infants.

Rice-starch based oral rehydration solution (ORS) has been shown to be a suitable alternative to glucose-based ORS in the treatment of both choleragenic and non-choleragenic dehydration in older infants and children. However, in young infants, the wider use of rice-starch ORS has been impeded because of theoretical concern about the poor digestibility of starch. The present study was conducted to evaluate the safety and efficacy of rice-starch ORS in the rehydration of acute diarrhoeal dehydration in infants below 6 months of age. Sixty-three infants with clinical features of acute gastroenteritis were randomly allocated to two groups. Group A, comprising 31 infants, received a rice-starch ORS and group B, comprising 32 infants, received a glucose-based ORS. The response to treatment was monitored by weight gain, stool frequency, and decrease in vomiting. The mean weight gain in moderately dehydrated and mildly dehydrated infants in both groups A and B were closely similar at 12, 24, and 48 h after treatment with the respective ORS solution. The infants without dehydration receiving rice-starch ORS had significantly greater weight gain at 12 h compared to those receiving glucose ORS. However, this difference was not observed at 24 and 48 h. The results of this study show that rice-starch ORS is as safe and efficacious as glucose-based ORS in young infants.

Dehydration↗
PubMed1995

Effects of hydroxyethyl starch after trauma-hemorrhagic shock: restoration of macrophage integrity and prevention of increased circulating interleukin-6 levels.

OBJECTIVES: To determine the effects of resuscitation with the colloidal solution (hydroxyethyl starch) vs. crystalloid solution on cell-mediated immune functions after trauma-hemorrhage. DESIGN: Prospective, multiexperimental, randomized, controlled study. SETTING: University research laboratory. SUBJECTS: Thirty-six inbred male C3H/HEN (endotoxin-sensitive) mice, aged 6 to 7 wks, and weighing 18 to 23 g. INTERVENTIONS: Crystalloid (lactated Ringer's solution) with and without 6% hydroxyethyl starch after trauma-hemorrhage. MEASUREMENTS AND MAIN RESULTS: Mice underwent laparotomy, were bled to and maintained at a blood pressure of 40 mm Hg for 60 mins, then resuscitated with either 4x the shed blood volume as lactated Ringer's solution or 2x the shed blood volume as lactated Ringer's solution plus 1 x 6% hydroxyethyl starch. Sham mice were neither hemorrhaged nor resuscitated. At 2 or 24 hrs posthemorrhage, serum, splenocytes, peritoneal macrophages, and splenic macrophages were obtained. Bioassays were used to determine interleukin-2, interleukin-3, and interleukin-6 concentrations, while splenocyte proliferation was assessed by 3H-thymidine incorporation. Trauma-hemorrhage markedly depressed splenocyte proliferation, interleukin-6 release by macrophages, and lymphokine release at 2 and 24 hrs postresuscitation. The combination of lactated Ringer's solution and hydroxyethyl starch neither restored, nor exacerbated lymphocyte functions. Interleukin-6 release by peritoneal macrophages was restored 24 hrs after hydroxyethyl starch infusion; serum interleukin-6 concentrations remained at sham levels. CONCLUSIONS: Since the use of lactated Ringer's solution and hydroxyethyl starch after hemorrhage did not adversely affect cell-mediated immune functions, but produced salutary effects on macrophage functions, hydroxyethyl starch is a safe and beneficial resuscitation adjunct.

Animals↗
PubMed2002

Starch biosynthesis during pollen maturation is associated with altered patterns of gene expression in maize.

Starch biosynthesis during pollen maturation is not well understood in terms of genes/proteins and intracellular controls that regulate it in developing pollen. We have studied two specific developmental stages: "early," characterized by the lack of starch, before or during pollen mitosis I; and "late," an actively starch-filling post-pollen mitosis I phase in S-type cytoplasmic male-sterile (S-CMS) and two related male-fertile genotypes. The male-fertile starch-positive, but not the CMS starch-deficient, genotypes showed changes in the expression patterns of a large number of genes during this metabolic transition. In addition to a battery of housekeeping genes of carbohydrate metabolism, we observed changes in hexose transporter, plasma membrane H(+)-ATPase, ZmMADS1, and 14-3-3 proteins. Reduction or deficiency in 14-3-3 protein levels in all three major cellular sites (amyloplasts [starch], mitochondria, and cytosol) in male-sterile relative to male-fertile genotypes are of potential interest because of interorganellar communication in this CMS system. Further, the levels of hexose sugars were significantly reduced in male-sterile as compared with male-fertile tissues, not only at "early" and "late" stages but also at an earlier point during meiosis. Collectively, these data suggest that combined effects of both reduced sugars and their reduced flux in starch biosynthesis along with a strong possibility for altered redox passage may lead to the observed temporal changes in gene expressions, and ultimately pollen sterility.

14-3-3 Proteins↗
PubMed2005

Daylength and circadian effects on starch degradation and maltose metabolism.

Transitory starch is stored during the day inside chloroplasts and broken down at night for export. Maltose is the primary form of carbon export from chloroplasts at night. We investigated the influence of daylength and circadian rhythms on starch degradation and maltose metabolism. Starch breakdown was faster in plants of Arabidopsis (Arabidopsis thaliana) ecotype Wassilewskija growing in long days. Transcript levels of genes encoding enzymes involved in starch degradation and maltose metabolism showed a strong diurnal rhythm. Under altered photoperiods, the transcript levels and the rate of starch degradation changed within one day/night cycle. However, the amount of proteins involved in starch degradation was maintained relatively constant throughout the day/night cycle. To investigate whether the diurnal cycling of the transcript levels is only a response to light or is also regulated by a circadian clock, we measured the amount of messenger RNAs in Arabidopsis leaves under continuous light and continuous darkness. The expression of genes encoding starch degradation-related enzymes was under very strong circadian control in continuous light. Under continuous light, the amount of maltose also showed a strong endogenous rhythm close to 24 h, indicating that maltose metabolism is under circadian control. Light is necessary for the cycling of transcript levels and maltose levels. Under continuous darkness, these genes were barely expressed, and no cycling of maltose levels was observed.

Arabidopsis↗
PubMed2005

Differential expression of sucrose-phosphate synthase isoenzymes in tobacco reflects their functional specialization during dark-governed starch mobilization in source leaves.

Sucrose (Suc)-phosphate synthase (SPS) plays a crucial role in the synthesis of Suc in photosynthetic and nonphotosynthetic tissues. Several isoforms of SPS exist in dicotyledonous plants that can be grouped into the different families A, B, and C. To explore whether functional differences between the SPS gene families might exist, we characterized a representative for each family from tobacco (Nicotiana tabacum). RNA-blot analysis revealed a distinct expression pattern for each of the three SPS genes. While the A-family member (NtSPSA) was found to be expressed in all tissues examined, expression of the B isoform (NtSPSB) was mainly confined to the reproductive organs and NtSPSC mRNA was exclusively detected in mature source leaves. We used RNA interference to assess the in planta function of NtSPSA and C. While silencing of NtSPSA had no detectable influence on leaf carbohydrate metabolism, reduction of NtSPSC led to an increase in leaf starch content by a factor of 3 to 8. Further analysis revealed that starch accumulation in NtSPSC-silenced plants was not due to an increased partitioning of carbon into starch, but rather showed that starch mobilization was impaired. The transgenic plants were unable to efficiently mobilize their transitory leaf starch during a prolonged period of darkness and accumulated maltose as a major intermediate of starch breakdown. NtSPSC mRNA level increased appreciably during the dark period while transcript levels of the other isoforms showed no diurnal changes. Together, these results suggest that NtSPSC is specifically involved in the synthesis of Suc during starch mobilization in the dark. The roles of the other SPS isoforms are discussed.

Amino Acid Sequence↗
PubMed1998

Characterization of a granule-bound starch synthase isoform found in the pericarp of wheat.

Waxy wheat (Triticum aestivum L.) lacks the waxy protein, which is also known as granule-bound starch synthase I (GBSSI). The starch granules of waxy wheat endosperm and pollen do not contain amylose and therefore stain red-brown with iodine. However, we observed that starch from pericarp tissue of waxy wheat stained blue-black and contained amylose. Significantly higher starch synthase activity was detected in pericarp starch granules than in endosperm starch granules. A granule-bound protein that differed from GBSSI in molecular mass and isoelectric point was detected in the pericarp starch granules but not in granules from endosperm. This protein was designated GBSSII. The N-terminal amino acid sequence of GBSSII, although not identical to wheat GBSSI, showed strong homology to waxy proteins or GBSSIs of cereals and potato, and contained the motif KTGGL, which is the putative substrate-binding site of GBSSI of plants and of glycogen synthase of Escherichia coli. GBSSII cross-reacted specifically with antisera raised against potato and maize GBSSI. This study indicates that GBSSI and GBSSII are expressed in a tissue-specific manner in different organs, with GBSSII having an important function in amylose synthesis in the pericarp.

Amino Acid Sequence↗
PubMed1999

The localization and expression of the class II starch synthases of wheat.

The starch granules of hexaploid wheat (Triticum aestivum) contain a group of three proteins known as SGP-1 (starch granule protein-1) proteins, which have apparent molecular masses of 100, 108, and 115 kD. The nature and role of these proteins has not been defined previously. We demonstrate that these polypeptides are starch synthases that are present in both the starch granule and the soluble fraction at the early stages of wheat endosperm development, but that are exclusively granule bound at mid and late endosperm development. A partial cDNA clone encoding a fragment of the 100-kD protein was obtained by screening a wheat endosperm cDNA expression library using monoclonal antibodies. Three classes of cDNA were subsequently isolated from a wheat endosperm cDNA library by nucleic acid hybridization and were shown to encode the 100-, 108-, and 115-kD proteins. The cDNA sequences are highly homologous to class II starch synthases and have the highest homology with the maize SSIIa (starch synthase IIa) gene. mRNA for the SGP-1 proteins was detected in the leaf, pre-anthesis florets, and endosperm of wheat and is highly expressed in the leaf and in the grain during the early to mid stages of development. We discuss the roles of the SGP-1 proteins in starch biosynthesis in wheat.

Amino Acid Sequence↗
PubMed1992

The rate of uptake and metabolism of starch grains and cellulose particles by Entodinium species, Eudiplodinium maggii, some other entodiniomorphid protozoa and natural protozoal populations taken from the ovine rumen.

The rates of engulfment and breakdown of starch grains and cellulose particles and of the rate of synthesis of amylopectin from cellulose by individual species of entodiniomorphid protozoa (grown in vivo and in vitro) and incubated anaerobically in vitro were studied. Rates of starch uptake varied from 2.3 to 770 micrograms/mg protozoal protein/min; the lowest was found with Diploplastron affine and the highest with Entodinium spp. on initial incubation with starch grains. The rate of starch breakdown varied from 0.49 to 8.6 micrograms/mg protein/min; the rate was dependent on the initial starch concentration inside the protozoa. Eudiplodinium maggii engulfed cellulose particles more rapidly (2-7 times) than rice starch grains and digested the cellulose at rates of 10 to 16.5 micrograms/mg protein/min. In a mixture of starch grains and cellulose particles, it engulfed the latter at 1.35 to 25 times the rate of the former. Eudiplodinium maggii and Epidinium caudatum, but not Entodinium spp. or Dip. affine, synthesized an amylopectin-like material from cellulose at rates of 0.4 to 4.75 micrograms/mg protein/min. If these reactions occur in the rumen in vivo, up to 9 g of amylopectin could be synthesized from cellulose each day by the entodiniomorphid protozoa.

Amylopectin↗
PubMed2006

The importance of maltose in transitory starch breakdown.

Starch content of leaves responds to environmental stresses in various ways. Understanding these environmental effects on starch metabolism has been difficult in the past because the pathways of transitory starch synthesis and degradation are not completely known. Over the past two years there has been a significant increase in our understanding of transitory starch breakdown. The discovery of a maltose transporter (MEX1) and the studies of a cytosolic disproportionating enzyme (D-enzyme, DPE2) confirmed that maltose is the predominant form of carbon exported from chloroplasts at night. Maltose increases in leaves when starch breakdown is induced during the day under photorespiratory conditions. Maltose metabolism is regulated by a circadian clock, day length and temperature. The expression of maltose-metabolizing genes shows a pronounced circadian rhythm indicating maltose metabolism is clock regulated. Indeed, the maltose level oscillates under continuous light. The transcript of a beta-amylase gene (BAM3) peaks during the day in long days and peaks at night in short days. This could provide a mechanism for adjusting starch breakdown rates to day length. Under cold-stress conditions, maltose increases and BAM3 expression is induced. We hypothesize that maltose metabolism is a bridge between transitory starch breakdown and the plants' adaptation to changes in environmental conditions.

Chloroplasts↗
PubMedDate not supplied

Site and extent of starch degradation in the dairy cow - a comparison between in vivo, in situ and in vitro measurements.

Prediction of the supply of glycogenic precursors to dairy cows and the site of degradation of wheat, maize and potato starch (PS) were determined in an in vivo experiment and the results were compared with data obtained from experiments involving in situ nylon bag and in vitro gas production techniques. In a Latin square design experiment four lactating dairy cows fitted with a rumen cannula and T-piece cannulae in the duodenum and terminal ileum, received either a low-starch control diet or diets in which sugar beet pulp in the concentrate mixture had been replaced by wheat, maize or PS. Starch from the different sources was almost completely degraded in the total gastrointestinal tract. For all starches, the rumen was the main site of degradation in vivo. No digestion of PS in the small intestine was observed. In situ results suggested that 14% of wheat starch (WS), 47% of maize starch and 34% of PS escaped rumen fermentation. According to the gas production technique WS ferments quickest and potato slowest. PS had a low degradability during the first 8 (gas production) to 11 (in situ) h. However, according to both in vitro and in vivo measurements rumen degradability of PS was high. The results suggest that in situ and in vitro techniques should be performed in animals that have adapted to starch source to provide a more accurate simulation of the in vivo situation.

Animal Feed↗
PubMed2006

Manipulation of starch granule size distribution in potato tubers by modulation of plastid division.

Starch granule size is an important parameter for starch applications in industry. Starch granules are formed in amyloplasts, which are, like chloroplasts, derived from proplastids. Division processes and associated machinery are likely to be similar for all plastids. Essential roles for FtsZ proteins in plastid division in land plants have been revealed. FtsZ forms the so-called Z ring which, together with inner and outer plastid division rings, brings about constriction of the plastid. It has been shown that modulation of the expression level of FtsZ may result in altered chloroplast size and number. To test whether FtsZ is also involved in amyloplast division and whether this, in turn, may affect the starch granule size in crop plants, FtsZ protein levels were either reduced or increased in potato. As shown previously in other plant species, decreased StFtsZ1 protein levels in leaves resulted in a decrease in the number of chloroplasts in guard cells. More interestingly, plants with increased StFtsZ1 protein levels in tubers resulted in less, but larger, starch granules. This suggests that the stoichiometry between StFtsZ1 and other components of the plastid division machinery is important for its function. Starch from these tubers also had altered pasting properties and phosphate content. The importance of our results for the starch industry is discussed.

Amino Acid Sequence↗
PubMed2004

Kinetics of enhanced ethanol productivity using raw starch hydrolyzing glucoamylase from Aspergillus niger mutant produced in solid state fermentation.

AIMS: The present investigation deals with the effect of raw starch hydrolyzing glucoamylase by a derepressed mutant of Aspergillus niger on enhanced productivity of ethanol from uncooked starch under non-aseptic conditions. METHODS AND RESULTS: The parental culture of Aspergillus niger was improved using gamma-ray treatment. One derepressed mutant was isolated after extensive screening and optimization and grown on corn cobs, maize starch, soluble starch and wheat bran solid media moistened with Vogel's salts solution and corn steep liquor. The mutant was 2.5-fold improved over its parent with respect to enzyme productivity, product yield and specific activity. The enzyme from mutated culture was also improved for enzyme properties and could effectively hydrolyze raw starch without the aid of alpha-amylase. Starch hydrolyzed with mutant-derived glucoamylase supported higher volumetric and product yields of ethanol than those of parental and other strains. SIGNIFICANCE AND IMPACT OF THE STUDY: The results of the present study are of commercial value. Ethanol product yield coefficient, and volumetric productivity revealed the hyper-productivity of ethanol from raw starch hydrolyzate obtained with mutant-derived glucoamylase without addition of liquefying alpha-amylase under non-aseptic conditions.

Aspergillus niger↗
PubMed1980

Net absorption of starch in low birth weight infants.

Twelve 3-day metabolic balance studies were carried out in 12 low birth weight infants fed an infant formula providing 3.5 g of corn starch per kilogram body weight per day. The mean coefficients of net absorption were 88 +/- 6% for starch, 70 +/- 14% for fat and 90 +/- 4% for nitrogen. No relationship was found between starch absorption and nitrogen or fat absorption. There was no relationship between starch absorption and the duration of starch feeding. It is concluded that the ability of young infants to digest large quantities of starch is most likely limited resulting from low pancreatic alpha-amylase activity. Nevertheless, from a practical point of view, small amounts of starch in infant formulas can be considered not only as a thickener but also as a source of calories.

Absorption↗