IP6 Content Research Articles

Optimisation of Phytate Degradation in Whole Grain Rice During Germination Processing Using Response Surface Methodology

Phytic acid (IP6), stored in seeds as metal salts known as phytates, binds to micronutrients and prevents its absorption by the human body. The germination process could improve cereal nutritional values by stimulating endogenous phytase activity and promoting phytate degradation. This study evaluated the physicochemical changes of phytates in rice cultivars with different IP6 contents, followed by optimisation of phytate degradation using response surface modeling. The magnitude of changes in IP6 content and phytase activity differed among rice cultivars. This suggested that the efficiency of germination treatments relied on the amount of natural phytic acid and phytase activity present in the rice grains. The cultivar “Tuan” was then selected and studied for the germination effect on phytate degradation using a central composite design. The cultivar gave a lower IP6 content, enhanced phytase activity and improved minerals bioaccessibility under acidic conditions. Acidic germination facilitated the degradation of phytate complexes in whole grain rice by making phytate complexes more soluble, accelerating phytase activity and thus, releasing mineral micronutrients from phytate globoids. The optimum germination condition was identified at pH 2.7, 25 °C over 12 h. In conclusion, germination processing facilitated phytate degradation in whole grain rice to make value-added rice products with low phytic acid and good mineral bioaccessibility.

Monitoring Intracellular IP6 with a Genetically Encoded Fluorescence Biosensor.

Inositol hexakisphosphate (IP6), a naturally occurring metabolite of inositol with specific functions in different organelles or tissues, participates in numerous physiological processes and plays a key role in mammalian metabolic regulation. However, current IP6 detection methods, i.e., high-performance liquid chromatography and gel electrophoresis, require sample destruction and lack spatiotemporal resolution. Here, we construct and characterize a genetically encoded fluorescence biosensor named HIPSer that enables ratiometric quantitative IP6 detection in HEK293T cells and subcellular compartments. We demonstrate that HIPSer has a high sensitivity and relative selectivity for IP6 in vitro. We also provide proof-of-concept evidence that HIPSer can monitor IP6 levels in real time in HEK293T cells and can be targeted for IP6 detection in the nucleus of HEK293T cells. Moreover, HIPSer could also detect changes in IP6 content induced by chemical inhibition of IP6-metabolizing enzymes in HEK293T cells. Thus, HIPSer achieves spatiotemporally precise detection of fluctuations in endogenous IP6 in live cells and provides a versatile tool for mechanistic investigations of inositol phosphate functions in metabolism and signaling.

Effect of bio-chemical changes due to conventional ageing or chemical soaking on the texture changes of common beans during cooking

To establish the HTC defect development, the cooking kinetics of seeds of ten bean accessions (belonging to seven common bean market classes), fresh and conventionally aged (35 °C, 83% RH, 3 months) were compared to those obtained after soaking in specific salt solutions (in 0.1 M sodium acetate buffer at pH 4.4, 41 °C for 12 h, or 0.01 M CaCl2 at pH 6.2, 25 °C for 16 h and subsequently cooking in CaCl2 solution, or deionised water). The extent of phytate (inositol hexaphosphate, IP6) hydrolysis was evaluated to better understand the role of endogenous Ca2+ in the changes of the bean cooking kinetics. A significant decrease in the IP6 content was observed after conventional ageing and after soaking in a sodium acetate solution suggesting phytate hydrolysis (release of endogenous Ca2+). These changes were accompanied by an increase in the cooking time of the beans. Smaller changes in cooking times after soaking in a sodium acetate solution (compared to conventionally aged beans) was attributed to a lower ionisation level of the COOH groups in pectin (pH 4.4, being close to pKa value of pectin) limiting pectin Ca2+ cross-linking. In beans soaked in a CaCl2 solution, the uptake of exogenous cations increased the cooking times (with no IP6 hydrolysis). The change in cooking time of conventionally aged beans was strongly correlated with the extent of IP6 hydrolysis, although two groups of beans with low or high IP6 hydrolysis were distinguished. Comparable trends were observed when soaking in CaCl2 solution (r = 0.67, p = 0.14 or r = 0.97, p = 0.03 for two groups of beans with softer or harder texture during cooking). Therefore a test based on the Ca2+ sensitivity of the cooking times, implemented through a Ca2+ soaking experiment followed by cooking can be used as an accelerated test to predict susceptibility to HTC defect development during conventional ageing. On the other hand, a sodium acetate soaking experiment can be used to predict IP6 hydrolysis of conventionally aged bean accessions and changes of cooking times for these bean accessions (with exception of yellow bean-KATB1).

Inositol hexaphosphate assisted polyamide thin-film composite membrane with ultrahigh performance for water desalination and dye fraction

Developing membranes with highly permeable and selective separation remains a challenge. Here, inositol hexaphosphate (IP6) was first introduced into the active layer for preparing an IP6 integrated polyamide (IP6PA) thin-film composite (TFC) membrane. The IP6PA TFC membrane possessed a thinner PA layer with a smoother and better hydrophilic surface as well as strengthened electronegativity and enlarged pore size. The IP6PA membrane that was prepared with a low IP6 content presented a high pure water flux of 20.5 LMH/bar (1.6 times higher than that of the control membrane), and a high Na2SO4 rejection rate (98.5 %), which could be used to completely remove typical dyes and natural organic matters. Notably, the IP6PA membrane fabricated with a high weight ratio of IP6 exhibited an ultrahigh water flux (111.7 LMH/bar) while maintaining superior rejections for Congo red (98.5 %), Direct red 23 (98.6 %), and Brilliant blue R250 (99.5 %). The results show that the modified membrane presented excellent performance in separation of organic/salts, particularly with its outstanding permeability and superior rejection rate, compared with those of most reported polymeric membranes. This work provides a new scheme for the rational design and manufacture of natural acid regulated polyamide composite membranes with enhanced performance for water treatment.

Effects of limestone solubility on the efficacy of a novel consensus bacterial 6-phytase variant to improve mineral digestibility, retention, and bone ash in young broilers fed low-calcium diets containing no added inorganic phosphate.

This study evaluated the effect of limestone solubility on the capacity of a novel consensus bacterial 6-phytase variant (PhyG) to improve phosphorus (P) and calcium (Ca) digestibility, retention, and utilization in low-Ca broiler diets containing no added inorganic phosphate (Pi). Male Ross 308 broilers (n = 1,152) were fed one of 16 experimental diets from 11 to 21 d of age in a randomized complete design (12 birds/cage, 6 cages/treatment). Diets comprised three positive controls (PC3, PC2, and PC1) containing 1.8, 1.2, or 0.6 g/kg MCP-P and 7.7, 7.0, or 6.2 g/kg Ca, respectively, and a negative control (NC) containing no added Pi (4.4 g/kg P; 2.8 g/kg phytate-P) and 5.5 g/kg Ca from either low or high solubility limestone (LSL or HSL, respectively, [with 42% and 97% solubility after 5 min at pH 3.0]), supplemented with 0, 250, 500, 1,000, or 2,000 FTU/kg of PhyG. Fecal samples collected on days 18 to 20 and ileal digesta collected on day 21 were analyzed for titanium dioxide, Ca, P, and phytate (IP6, inositol hexakisphosphate). Tibias (day 21) were analyzed for ash content. Data were analyzed by factorial analysis (2 limestone solubilities × 4 MCP-P levels and 2 limestone solubilities × 5 phytase dose levels) and exponential regression. Increasing dose levels of PhyG resulted in an exponential increase (P < 0.01) in the apparent ileal digestibility (AID) of P, ileal digestible P content of the diet, ileal IP6 content, and IP6 disappearance in birds fed either HSL or LSL diets, but AID Ca and ileal digestible Ca were exponentially increased by the phytase only in HSL diets (P < 0.01). Relative to HSL, the LSL increased AID P, ileal digestible P, and IP6 disappearance (P < 0.05) but reduced AID Ca, ileal digestible Ca, and retainable Ca (P < 0.05), resulting in reduced retainable P and tibia ash. Phytase exponentially increased the apparent total tract digestibility of P, retainable P, and tibia ash in HSL and LSL diets, but at or above 500 FTU/kg values were higher in HSL than LSL (interaction P < 0.05). The findings highlight that phytase dose-response effects on mineral digestibility and utilization are different for high- and low-solubility limestones, and it is therefore recommended to use digestible rather than total Ca content during diet formulation to ensure an optimal balance of Ca and P, especially in low-Ca diets. In diets containing HSL, higher phytase dose levels may be needed to compensate for the low digestible P content of the basal diet.

Calcium transport and phytate hydrolysis during chemical hardening of common bean seeds

In this study, two chemical bean seed hardening methods were used to investigate the changes in cooking behavior associated with Ca2+ transport and phytate hydrolysis to better understand their role in the pectin-cation-phytate hypothesis. The texture evolution of fresh and hardened red kidney beans was evaluated, hardening being induced by soaking or in a CaCl2 solution (0.01 M, 0.05 M, 0.1 M) or sodium acetate buffer (0.1 M, pH 4.4, 41 °C). The beans soaked in a CaCl2 solution at higher concentrations or in sodium acetate buffer for a longer time exhibited a delayed cooking behavior. This study also explored the bio-chemical changes (calcium content in different bean substructures, phytate content and the pectin degree of methylesterification (DM) in the cotyledons) occurring in the beans during chemical hardening and cooking. The Ca2+ concentrations in the whole beans and cotyledons of beans soaked and cooked in CaCl2 solutions significantly increased while inositol hexaphosphate IP6 content showed no significant changes. This indicates that the delayed texture drop in this case results from the influx of exogenous Ca2+ in the cotyledons and seed coats during cooking while the IP6 was not hydrolyzed and did not release endogenous Ca2+. For beans soaked in sodium acetate buffer, phytate profiling showed increased hydrolysis of IP6 with longer soaking time, suggesting the migration of endogenous Ca2+ released from phytate hydrolysis contributing to the delayed cooking of these beans. These results indicate that both an exogenous Ca2+ influx during soaking and cooking and an endogenous Ca2+ replacement resulting from phytate hydrolysis can play an important role in the hardening of beans. In neither of the cases, a significant change in pectin DM was observed during chemical hardening, therefore limiting the delayed cooking to the role of Ca2+ transport. The outcome of both cases is inline with the basic principles of the pectin-cation-phytate hypothesis whereby pectin DM changes are hardly involved and different mechanisms of release/transport are involved.

115 Functionality of a novel consensus bacterial 6-phytase variant on ileal phytate degradation in weaned piglets fed diets without inorganic phosphate

Abstract Microbial phytases are used in animal feed to hydrolyze phytic acid (myo-inositol hexakisphosphate, IP6) and phytate (salt of phytic acid), to improve phosphorus (P) bioavailability. This study evaluated the efficacy of a novel consensus bacterial 6-phytase variant (PhyG) on ileal IP6 degradation in piglets. A positive control diet was formulated based on corn and soybean meal with adequate digestible P (2.9g/kg) and calcium (Ca, 7.0g/kg). A negative control (NC) diet was formulated without inorganic P (1.1 g digestible P/kg), reduced in Ca (5.0 g/kg) with analyzed phytate P of 2.6g/kg. This diet was supplemented with PhyG at 250, 500 and 1,000 FTU/kg. A total of 90 crossed Pietrain x (large White x Landrace) 21-d-old piglets were fed adaptation diets until 42 d old and then assigned to pens (2 pigs/pen and 9 pens/treatment) in a completely randomized block design. Piglets were fed mash diets ad libitum for 28 d, at the end of the study 1 piglet/pen was euthanized for collecting ileal digesta samples for determination of IP6 digestibility, using TiO2 as a marker. Data was analyzed by one-way ANOVA using JMP 14.0 with treatment comparison by Tukey test and dose response by curve fitting. The ileal IP6 content was reduced with increasing phytase dose in a dose dependent manner (Plinear &amp;lt; 0.0001; Pexponential = 0.08). Similarly, the ileal IP6 digestibility increased exponentially (P &amp;lt; 0.05) with increasing phytase dose (49.1% for NC and 89.3% for PhyG at 1,000 FTU/kg). Improved ileal IP6 digestibility is closely related to improved bone ash, body weight gain and feed conversion ratio (R2 &amp;gt; 0.91). The in vitro IP6 degradation profile supports these in vivo observations. The results demonstrated that the novel consensus phytase variant is highly efficient in hydrolyzing phytate and increasing the bio-availability of phytate bound P in piglets fed diets without inorganic phosphate.

Allelic Variants of CRISPR/Cas9 Induced Mutation in an Inositol Trisphosphate 5/6 Kinase Gene Manifest Different Phenotypes in Barley.

Inositol trisphosphate 5/6 kinases (ITPK) constitute a small group of enzymes participating in the sequential phosphorylation of inositol phosphate to inositol hexakisphosphate (IP6), which is a major storage form of phosphate in cereal grains. The development of lines with reduced IP6 content could enhance phosphate and mineral bioavailability. Moreover, plant ITPKs participate in abiotic stress signaling. To elucidate the role of HvITPK1 in IP6 synthesis and stress signaling, a barley itpk1 mutant was created using programmable nuclease Cas9. Homozygous single bp insertion and deletion mutant lines were obtained. The mutants contained altered levels of phosphate in the mature grains, ranging from 65% to 174% of the wild type (WT) content. Homozygous mutant lines were tested for their response to salinity during germination. Interestingly, insertion mutant lines revealed a higher tolerance to salinity stress than deletion mutants. Mature embryos of an insertion mutant itpk1-2 and deletion mutant itpk1-33 were cultivated in vitro on MS medium supplemented with NaCl at 50, 100, and 200 mM. While both mutants grew less well than WT on no or low salt concentrations, the itpk1-2 mutant was affected less than the WT and itpk33 when grown on the highest NaCl concentration. The expression of all ITPKs was induced in roots in response to salt stress. In shoots, the differential effect of high salt on IPTK expression in the two iptk1 mutants was consistent with their different sensitivities to salt stress. The results extend the evidence for the involvement of ITPK genes in phosphate storage and abiotic stress signaling.

Reduction of β-ODAP and IP6 contents in Lathyrus sativus L. seed by high hydrostatic pressure

Grass pea (Lathyrus sativus L.) seeds contain an endogenous neurotoxic non-proteinogenic amino acid, β-N-oxalyl-l-α,β-diaminopropionic acid (β-ODAP), a major limiting factor-for their human consumption. Furthermore, phytate (IP6), a well-known antinutrient is present in concentration capable of hindering bioavailability of iron (Fe), zinc (Zn), calcium (Ca), phosphorus (P) and other micronutrients from the seeds. Due to the reported capability of high hydrostatic pressure (HHP) to reduce the content of certain antinutritional/toxic agents in seeds and grains, the impact of HHP on the reduction of β-ODAP and IP6 were investigated. The contents of β-ODAP of accessions from different regions in Ethiopia were found to be in the range of 51.94 to 806.52 mg/100 g. Accession (GF1- Alemu, AK) exhibiting the highest β-ODAP content was selected for HHP treatment in soaked and batter forms using Central Composite Face Centered Design of experiments. The best HHP conditions in respect to β-ODAP reduction were also applied to the accession (GP-240038) with the lowest β-ODAP-content, a genetically improved variety (Wassie) and a variety from Germany (GR). The HHP treatment at 600 MPa for 25 min of seeds soaked for 6 h and 12 h exhibited the maximum reduction of β-ODAP (232.11 mg/100 g) and IP6 (21.11 mg/100 g) respectively. The combined incremental effect of pressure and soaking time resulted in a more significant (p ≤ .001) reduction in both compounds than the interaction of pressure with holding time (p ≤ .05). A reduction of β-ODAP from 36.00 to 71.22% by soaked-HHP treatment was observed. β-ODAP reductions were always higher for soaked compared to batter grass pea seeds. IP6 contents after HHP treatment ranged from 33.65 mg/100 g to nill. It can be concluded that pressure, soaking and holding time as well as the grass pea seed accession/variety had great impact on molecular structure changes, enhancement of enzyme activity and reduction in β-ODAP and IP6 content.

Effect of soaking and inositol phosphate content on in vitro mineral availability in edible seaweeds

Seaweeds are an ideal food-safe natural source of minerals with a potential use in human nutrition. However, the presence of phytate and different treatments before consumption could modify mineral availability. The content and in vitro mineral availability after a simulated gastrointestinal digestion of wakame (Undaria pinnatifida), nori (Porphyra spp.), sea salad (Ulva lactuca, Palmaria palmata, Undaria pinnatifida, Porphyra spp., Laminaria spp.), and sea spaghetti (Himanthalia elongata) were studied. Experiments were assessed after a soaking treatment of seaweeds with cold (20 °C) or hot (70 °C) water, as usually processing before eating. Moreover, inositol phosphate content was determined in the edible macroalgae and the molar ratio phytate/mineral was used as a predictor of the relative availability of minerals. Overall, edible analyzed seaweeds showed a high Ca, Fe, P, and K contents, highlighting wakame for all the studied minerals. In all cases, soaking in cold water showed the highest soluble and dialyzable mineral fractions. High content of phytic acid (IP6) was observed in sea salad (≈ 25 mg (100 g)−1); meanwhile, sea spaghetti showed the lowest IP6 content (3.9 mg (100 g)−1). The low molar ratios Phy/Ca and Phy/Zn obtained in seaweeds could indicate an adequate availability. However, ratios Phy/Fe could compromise the iron availability in wakame, nori, and sea spaghetti. Results obtained confirm that external factor such as soaking, gastrointestinal digestion, and inositol phosphates can affect the mineral availability. Consumption of edible seaweeds can be recommended for the necessary intake of available minerals and trace elements.

Hydration mechanism of a calcium phosphate cement modified with phytic acid

Calcium phosphate cements composed of β-tricalcium phosphate (β-TCP) and phosphoric acid were modified by addition of 5, 10, 12.5, 15 and 20 wt% phytic acid (IP6) related to the β-TCP content and compared to a reference containing 0.5 M citric acid monohydrate solution as setting regulator. The hydration reaction of these cements was investigated by isothermal calorimetry and in-situ X-ray diffraction at 23 °C and 37 °C. The cements were further characterized with respect to their injectability, rheology, zeta potential and time-resolved compressive strength development.Injectability was strongly improved by IP6 addition, while the maximum effect was already reached by the addition of 5 wt% IP6. This could be clearly related to an increase of the negative zeta potential leading to a mutual repulsion of cement particles. A further increase of the IP6 content had a detrimental effect on initial paste viscosity and shifted the gelation point to earlier time points. IP6 was further proven to act as a retarder for the cement setting reaction, whereas the effect was stronger for higher IP6 concentrations. Additionally, IP6 favoured the formation of monetite instead of brushite and a better mechanical performance compared to the IP6 free reference cement. Statement of SignificanceCalcium phosphate cements (CPCs) are clinically applied for bone repair due to their excellent biocompatibility and bone regeneration capacity. A deep understanding of the setting mechanism is the prerequisite for the targeted fabrication and application of such bone cements, whereas setting characteristics are usually adjusted by additives. Here, novel injectable CPC formulations were developed by modifying a cement composed of β-tricalcium phosphate and phosphoric acid with phytic acid (IP6). A detailed investigation of the setting mechanism of the IP6 modified CPCs is provided, which demonstrated the effectiveness of IP6 as setting regulator to adjust the reaction time and kind of setting product. Additionally, the high surface charge of cement particles after IP6 addition was effective in dispersing cement particles leading to low viscous cement pastes, which can be directly applied through a syringe for minimal invasive surgery.

Assessment of iron bioavailability from different bread making processes using an in vitro intestinal cell model

Myo-inositol hexakisphosphate (IP6), is the main iron chelator in cereals and bread. The aim of this study was to investigate the effect of three commercial baking processes (sourdough, conventional yeast and Chorleywood Bread Making Process (CBP)) on the IP6 content of wholemeal bread, its impact on iron uptake in Caco-2 cells and the predicted bioavailability of iron from these breads with added iron, simulating a mixed-meal. The sourdough process fully degraded IP6 whilst the CBP and conventional processes reduced it by 75% compared with wholemeal flour. The iron released in solution after a simulated digestion was 8-fold higher in sourdough bread than with others but no difference in cellular iron uptake was observed. Additionally, when iron was added to the different breads digestions only sourdough bread elicited a significant ferritin response in Caco-2 cells (4.8-fold compared to the other breads) suggesting that sourdough bread could contribute towards improved iron nutrition.

English

The plant, jatropha has attracted worldwide attention for its high oil content. The use of high performance liquid chromatography (HPLC) to separate and quantify, for the first time, the phytic acid (inositol hexaphosphate) and lower inositol phosphates (tri-, tetra- and penta-phosphates; IP6, IP5, IP4 and IP3) in toxic and non-toxic (NT) Jatropha curcas seeds from different locations in Mexico was proposed. There are reports on the total phytic acids but the method of precipitation used was not specific to distinguish between the phytic acid (IP6) and its hydrolysis products; therefore, this technique underestimates the IP6 content. It was observed that the total inositol concentration is independent on the presence or absence of phorbolesters (PE). The analysis showed that the toxic seeds from Villaflores and Chiapa de Corzo had high concentrations of total IP (46.2 and 42.5 mg/g, respectively) but the NT seeds from Huitzilan is the highest (56.88 mg/g) followed by Pueblillo (41.427 mg/g), Cuautla (37.832 mg/g) and Xochitlan (35.868 mg/g) showed higher values of IP. Finally, the toxic seeds from Coatzacoalcos (22.5 mg/g) showed lower value. This is the first work showing the different inositol phosphates present in jatropha seed samples, highlighting the presence of hexaphosphate acid as the major component. Key words: Phytic acid, high performance liquid chromatography (HPLC), anti-nutrients, phytates, IP5, IP6, hexaphosphate.

Effect of popping and fermentation on proximate composition, minerals and absorption inhibitors, and mineral bioavailability of Amaranthus caudatus grain cultivated in Ethiopia.

This study evaluated the effect of popping and fermentation on the chemical composition of three types of Amaranthus caudatus grains cultivated in Ethiopia. Proximate composition, minerals and mineral absorption inhibitors were analyzed. Popping caused a decrease in protein content by 4% and an increase in fat, ash, acid detergent fiber (ADF) and neutral detergent fiber (NDF) contents by 12, 10, 15 and 67%, respectively. While fermentation increased protein, fat and ash content by 3, 22 and 14%, respectively but did not significantly change ADF and NDF content. Fe, Ca and phytic acid (IP6) decreased during popping but Mg, Zn, galloyl and catechol did not change significantly. On the other hand, fermentation increased Fe and Mg content but decreased IP6, galloyl and catechol content. The decrease in mineral absorption inhibitors especially IP6 during popping and fermentation could contribute to enhance mineral bioavailability. However, due to the presence of high phytate content in raw amaranth, all IP6-to-mineral molar ratios were above the recommended values.

Arabidopsis inositol pentakisphosphate 2-kinase, AtIPK1, is required for growth and modulates phosphate homeostasis at the transcriptional level.

Inositol hexakisphosphate (IP6 ) provides a phosphorous reservoir in plant seeds; in addition, along with its biosynthesis intermediates and derivatives, IP6 also plays important roles in diverse developmental and physiological processes. Disruption of the Arabidopsis inositol pentakisphosphate 2-kinase coding gene AtIPK1 was previously shown to reduce IP6 content in vegetative tissues and affect phosphate (Pi) sensing. Here we show that AtIPK1 is required for sustaining plant growth, as null mutants are non-viable. An incomplete loss-of-function mutant, atipk1-1, exhibited disturbed Pi homeostasis and overaccumulated Pi as a consequence of increased Pi uptake activity and root-to-shoot Pi translocation. The atipk1-1 mutants also showed a Pi deficiency-like root system architecture with reduced primary root and enhanced lateral root growth. Transcriptome analysis indicated that a subset of Pi starvation-responsive genes was transcriptionally perturbed in the atipk1-1 mutants and the expression of multiple genes involved in Pi uptake, allocation, and remobilization was increased. Genetic and transcriptional analyses suggest that disturbance of Pi homeostasis caused by atipk1 mutation involved components in addition to PHR1(-like) transcription factors. Notably, the transcriptional increase of a number of Pi starvation-responsive genes in the atipk1-1 mutants is correlated with the reduction of histone variant H2A.Z occupation in chromatin. The myo-inositol-1-phosphate synthase mutants, atmips1 and atmips2 with comparable reduction in vegetative IP6 to that in the atipk1-1 mutants did not overaccumulate Pi, suggesting that Pi homeostasis modulated by AtIPK1 is not solely attributable to IP6 level. This study reveals that AtIPK1 has important roles in growth and Pi homeostasis.

HYDROLYSIS OF PHYTATE IN BROWN RICE-ADDED BREAD BY ADDITION OF CRUDE AND PURIFIEDASPERGILLUS NIGERPHYTASE PREPARATIONS DURING BREAD MAKING

ABSTRACT Brown rice-added breads were prepared with and without crude and purified Aspergillus niger phytase preparations. By adding 30% (w/w) brown rice flour and no phytase preparation, the phytate (myo-inositol hexaphosphate; IP6) content of the bread was increased and the loaf volume was reduced. The direct addition of a food-additive grade phytase preparation (3,000 U) resulted in a significant decrease in the IP6 content. However, it collapsed the bread crust. The crude phytase preparation had significant protease and amylase activities. A simple chromatographic method for the separation of phytase activity from the protease and amylase activities was developed. By using purified phytase, the IP6 content was reduced without any adverse effects on the rising of the bread, which indicates that protease and amylase may be responsible for the collapse of the crust by the commercial phytase preparation. PRACTICAL APPLICATIONS Phytate in unrefined cereals and beans lowers bioavailability of minerals. On the other hand, these materials are rich in health-promoting components. To reduce the phytate in them during processing, some commercially available phytase preparations are now used. However, we found that such preparation contains significant amylase and protease activities, which may cause adverse effect on the appearance and textural properties of final products. To solve these problems, a simple and inexpensive procedure for separation of phyatase from amylase and protease was developed in the present study. The purified phytase can reduce phytate in brown rice-added bread without adverse effect on rising of bread. These results would encourage prepare the phytase preparation in high purity in an industrial scale to improve nutritional value of unrefined cereal- and bean-based functional foods.

Effects of three conventional cooking methods on vitamin C, tannin, myo-inositol phosphates contents in selected Thai vegetables

Vegetables commonly consumed in Thailand were analyzed for their vitamin C, tannin and total phytate (inositol penta- (IP5) and hexasphosphate (IP6)) contents. Three conventional household cooking methods, namely blanching, boiling and stir-frying, were used to evaluate the effects of cooking. IP5 and IP6 content were determined using ion-pair reverse-phase chromatography. Vitamin C and tannin content were analyzed spectrophotometrically. Vitamin C content for raw and cooked vegetables ranged from 0.5–83.6 to 0.2–70.8 mg/100 g, respectively. Stir-fried pagwanpa ( Melientha suavis Pierre.), pagwanban ( Sauropus andogynus (L) Merr.) and cowslip creeper flower ( Telosma minor Craib) were excellent sources of vitamin C (64.4–70.8 mg/100 g). High tannin content was found in lead tree (“Yod-kratin”, Acacia farnesiana Willd.; 1353 and 679 mg/100 g tannic acid equivalent for raw and blanched sample, respectively), while neem tree ( Azdirachta indica A. Juss) contained high phytate (52 and 38 mg/100 g for raw and blanched sample, respectively). Blanching, stir-frying and boiling caused a decrease in the total vitamin C, with losses from 14% to 95%, the greatest loss being found in boiled bitter cucumber ( Monordica charantia Linn.) (95%), whereas retention of total phytate and tannin was around 58–79% for phytate and 44–93% for tannin. Although conventional boiling method was an effective method to reduce tannin and phytate content in vegetables, it also reduced the content of vitamin C.

Phytase activity and degradation of phytic acid during rye bread making

Changes in phytic acid content, activity of phytase and α-amylase in rye breads were determined during rye bread making. The activity of phytase is highest in grain and flour whereas the activity in the sourdoughs is almost the half of the activity in the flour. The activity was unchanged in the dough after mixing and proofing. Degradation of phytic acid (IP6) into lower inositol phosphates and free phosphate is almost completed during the production of rye bread with long fermentation time whereas the degradation is less completed when whole grains are included in the recipe. In rye bread made from milled rye (DB00), 99% of IP6 is degraded and IP3 becomes the dominating inositol phosphate in this bread type presumably resulting in a high level of bioavailable minerals. In rye bread made with 30% grains (SB30), 94% of the IP6 content was reduced with IP4 and IP3 being the dominating lower inositol phosphates. In rye bread made with 50% whole grains (KB50) the degradation of IP6 was 82%, and the three inositol phosphates IP5, IP4 and IP3 were found in equal amount in this bread type. Due to significant amounts of phytic acid and remaining IP5, some of the minerals might not be available for human absorption after consumption of this bread type.

Use of soaking to enhance the bioavailability of iron and zinc from rice‐based complementary foods used in the Philippines

AbstractComplementary foods used in the Philippines are predominantly rice‐based, although enrichment with mung beans and sesame seeds is recommended despite their high content of phytic acid, a potent inhibitor of iron and zinc absorption. We have investigated the effect of soaking on the inositol penta‐ (IP5) and hexaphosphate (IP6) (analysed by HPLC), zinc, iron and calcium (via AAS) content of rice‐based complementary foods with and without the addition of mung beans and sesame seeds. Soaking rice flour for 1, 6 and 12 h at 30 °C reduced the content of IP5 + IP6 by 60, 65 and 98% respectively, with only slight changes in zinc, iron and calcium. Levels of IP5 + IP6 were reduced by 10 and 47% by soaking mung bean flour, but not whole beans, for 1 and 6 h respectively. In conclusion, soaking can be used to reduce the IP5 and IP6 content of complementary foods based on mung bean flour and/or rice flour and thus enhance the bioavailability of iron and zinc.© 2002 Society of Chemical Industry

Effect of local food processing on the inositol phosphate contents in lima bean (Phaseolus lunatus L.); pigeon pea (Cajanus cajan); African yam bean (Sphenostylis sternocarpa) and jackbean (Canavalia ensiformis)

The effects of cooking in water or alkaline solution, soaking and germination on the individual inositol phosphates (IP3 to IP6), and total inositol phosphates (IP) content of lima bean, pigeon pea, African yam bean, and jackbean were investigated. Inositol triphosphate was not detected in any of the legumes studied. The predominant inositol phosphate in all the legumes was inositol hexaphosphate (IP6). Raw white lima bean contained the highest quantity of IP6, 0.350 mg/100 mg. Pigeon pea contained 0.289 mg/100 mg IP6 in the brown and cream varieties. Jackbean contained 0.242 mg/100 mg IP6 while African yam bean had the lowest IP6 content of 0.139 mg/100 mg. All processing methods reduced the total IP to various extents. Germination led to a reduction of 85% of total IP in white lima bean. Cooking reduced IP6 by 39–65% in all the grain legumes while cooking in alkaline solution reduced total IP up to 80% in cream pigeon pea.