Fermentation and enzyme treatment of tannin sorghum gruels: effects on phenolic compounds,phytate and in vitro accessible iron

The presence of polyphenols and phytate in cereal products has been shown to interfere with the bioavailability of minerals such as iron. In the present study, we added enzymes (wheat phytase and mushroom polyphenol oxidase) during fermentation of tannin sorghum gruels prepared from flour with or without addition of 5% flour of germinated tannin-free sorghum grains (power flour), and investigated the effects on phenolic compounds, phytate and in vitro accessible iron. Assayable phenolic compounds were significantly reduced by fermentation, with high reductions observed in gruels with added enzymes. Fermentation of the gruels with addition of enzymes reduced (on average) total phenols by 57%, catechols by 59%, galloyls by 70% and resorcinols by 73%. The phytate content was significantly reduced by fermentation (39%), with an even greater effect after addition of power flour (72%). The largest reduction of phytate (88%) was, however, obtained after addition of phytase. The in vitro accessible iron was 1.0% in the sorghum flour and it increased after fermentation with power flour and/or with enzymes. The highest in vitro accessibility of iron (3.1%) was obtained when sorghum was fermented with addition of power flour and incubated with phytase and polyphenol oxidase after the fermentation process.     

Phytate Hydrolysis by Phytase in Cereals; Effects on In Vitro Estimation of Iron Availability

Phytate (inositol hexaphosphate) hydrolysis by endogenous and exogenous phytases was studied for their effect on increasing iron availability in cereals. Wheat bran and whole meal flours of rye and oats were soaked at optimal conditions for phytase activity (55°C, pH 5) for different time intervals. Phytate and its degradation products were determined by HPLC and related to iron solubility under simulated physiological conditions. Small amounts of phytate (< lμmol/g) had a strong negative effect on iron solubility. When inositol hexa- and pentaphosphates of wheat bran and rye flour were completely hydrolyzed by activating endogenous phytase, iron solubility under simulated physiological conditions increased from 3 to 53% (wheat) and 5 to 21% (rye). Addition of wheat phytase to uncooked oatmeal increased iron solubility from 4 to 11 and in precooked to 18%, while endogenous phytase of uncooked oatmeal had less effect on phytate digestion and iron solubility.     

Peniophora lycii phytase is stabile and degrades phytate and solubilises minerals in vitro during simulation of gastrointestinal digestion in the pig

BACKGROUND: Microbial phytases (EC 3.1.3) are widely used in diets for monogastric animals to hydrolyse phytate present in the feed and thereby increase phosphorus and mineral availability. Previous work has shown that phytate solubility is strongly affected by calcium in the feed and by pH in the gastrointestinal (GI) tract, which may have an effect on phytase efficacy. An in vitro model simulating the GI tract of pigs was used to study the survival of Peniophora lycii phytase and the effect of the phytase on phytate degradation, inositol phosphate formation and mineral solubilisation during in vitro digestion of a 30:70 soybean meal/maize meal blend with different calcium levels. RESULTS: The phytase retained 76 and 80% of its initial activity throughout the gastric in vitro digestion. Total phytate hydrolysis by P. lycii phytase was in the same range at total calcium levels of 1.2 and 6.2 mg g^?1 dry matter (DM), despite very large differences in phytate solubility at these calcium levels. However, at 11.2 and 21.2 mg Ca g^?1 DM, phytate hydrolysis was significantly lower. The amount of soluble mineral was generally increased by P. lycii phytase. CONCLUSION: Stability of P. lycii phytase during gastric digestion was not found to be critical for phytate hydrolysis. Furthermore, original phytate solubility was not an absolute requirement for phytate degradation; phytate solubility seemed to be in a steady state, allowing insoluble phytate to solubilise as soluble phytate was degraded. This is new and interesting knowledge that adds to the current understanding of phytate–phytase interaction. Copyright © 2007 Society of Chemical Industry     

Supplementation of alkaline phytase (Ds11) in whole-wheat bread reduces phytate content and improves mineral solubility

Abstract: In this study, alkaline phytase was added to whole‐wheat bread and the phytate content and mineral profiles were compared to commercially available acidic phytase. At neutral pH, some phytate (approximately 20%) was degraded by endogenous phytase in wheat flour, while 40% of phytate was hydrolyzed by alkaline phytase DS11 and a 35% reduction was observed with acidic phytase. Most of the enzymatic activity occurred during the proofing stage, and the rate of reaction depended on pH. DS11 phytase effectively degraded the phytate level within a 30 min treatment at pH 7; however, at least 60 min was needed with acidic phytase to achieve the same hydrolysis level. Mineral profiles were also dramatically affected by the phytate reduction. The biggest increase was observed in Fe²⁺ by the phytase treatment. The Fe²⁺ content increased 10‐fold at pH 7 and 8‐fold at pH 5 with alkaline phytase DS11. Alkaline phytase DS11 was shown to be effective at phytate reduction in whole‐wheat bread preparation. Additionally, phytate degradation enhanced the mineral availability of bread.     

Enzymatic Reduction of Phytate in Whole Wheat Breads

The presence of phytate in flour may be responsible for reduced bioavailability of iron, magnesium, zinc, and calcium from bread. The effect of various concentrations of commercial phytase or phosphatase added to whole wheat flour-yeast doughs on their phytate and nonphytate phosphorus content has been investigated. By using 2.0% (flour basis) of phytase and 0.11% phosphatase the initial phytate phosphorus concentration of the dough was reduced to 1/8 and 1/12 of its initial values, respectively. Storage of the whole wheat breads for up to 96 hr at room temperature showed further significant reduction of phytate phosphorus. The phytate phosphorus content of yeast leavened whole wheat breads decreased during 2 hours of dough fermentation, baking and the subsequent 48 hours of storage at room temperature from 24 mg/100g dough (dry matter) to 1.7 mg/100g bread (dry matter); the phytate phosphorus continued to decrease and after 96 hours storage it was 0.6 mg/100g bread.     

The effects of germination,fermentation, and fermentation additives on the phytate content of rice flour

The phytate contents in nine rice cultivars (Oryza sativa cv.) grown in Korea were investigated and the effects of germination, fermentation, and fermentation additives on the phytate content of rice flour were studied. In nondehulled paddy rice, the phytate content was the highest in Goamibyeo and the lowest in Hanareumbyeo. In milled rice, the phytate content was the highest in Suweon517 and the lowest in Manmibyeo. For Goamibyeo, which had high phytate contents both before and after milling, there was a significant (p<0.05) reduction in the phytate content of paddy rice after germination. The phytate content reduction occurred when germinated paddy flour was fermented at 50°C for 24 h. Paddy rice phytate was completely removed when ammonium sulfate was added to germinated paddy rice flour, which was then allowed to ferment at 50°C for 24 h.     

Phytic Acid Hydrolysis and Soluble Zinc and Iron in Whole Wheat Bread As Affected by Calcium Containing Additives

The effects of nonfat dry milk, CaCO₃, CaCl₂ and MgCl₂ on phytate hydrolysis and on Zn and Fe availability was evaluated in whole wheat bread and in a model fermentation system. CaCO₃ and CaCl₂ both depressed phytate hydrolysis to an equivalent degree, but the milk had a greater effect than could be accounted for by its Ca content. MgCl₂ had a less pronounced effect than the Ca salts in both the bread and the model system. Increasing fermentation time in the model system increased phytate hydrolysis, but the effect was delayed when milk or CaCl₂ was added. Supplementing the bread dough with Ca equivalent to that typically contributed by Ca-containing additives caused 50% reductions in the available quantities of soluble (“free”) zinc and iron; the decreases observed with varying added amounts of Ca or milk exhibited a high degree of correlation with the observed increases in residual phytate P.     

Improved iron solubility in carrot juice fermented by homo- and hetero-fermentative lactic acid bacteria

To evaluate lactic acid fermentation as a means to increase the availability of iron in carrot juice, two strains (Lactobacillus pentosus FSC1 and Leuconostoc mesenteroides FSC2), two types of carrot juice and two modes of fermentation were compared. Fermentation improved iron solubility up to 30 fold. The total mineral content and the yield of soluble iron differed between the two types of juice. Addition of pectolytic enzyme and cellulase further improved iron solubility in fermented juice by about 10%. L. pentosus FSC1 yielded the largest improvement in soluble iron, which was not simply a result of a decrease in pH. The concentration of soluble iron in Ln. mesenteroides FSC2 fermentation was linearly related to the major acids produced. Besides, the mineral inhibitor phytate was completely degraded in all the fermentations.Lactic acid fermentation strongly improves iron solubility in carrot juice. The level of improvement was strain specific and related to the produced acids rather than a simple pH effect. Composition of carrot juice and addition of viscosity-reducing enzymes also contributed to this improvement. Our study suggests that carrot juice with high mineral availability may be achieved by fermentation using selected starter cultures, substrate and process.     

Zinc and Phytate Distribution in Peas. Influence of Heat Treatment, Germination, pH, Substrate, and Phosphorus on Pea Phytate and Phytase

The largest proportions of zinc and phytate, 88.7 and 97.1%, respectively, were in the Garfield pea cotyledon; the greatest concentrations were in the germ. Cooking peas by two different methods resulted in 13% phytate reduction. Peas incubated 6.5 hr from 25 to 80°C yielded maximum phytate loss (25%) at 60°C due to phytase activated hydrolysis. Germination (10 d) decreased pea phytate 75% and increased phytase activity 12-fold. Semi-purified germinated pea phytase showed temperature optimum at 45°C, pH optimum of 5.2, 30% inhibition by 1 mM inorganic P, and substrate preference for pyrophosphate. Incubation of early germinated peas at optima pH and temperature is suggested for maximum phytate reduction.     

Phytate content of some foods from plant origin from Vietnam and Hungary

For the estimation of phytate-ion the iron content of FeIII-phytate complex was determined by spectrophotometry with o-phenanthroline. In most cases phytate-phosphorus was also evaluated. In different food samples iron to phosphorus ratio in phytate generally deviated significantly from the theoretical 1.20 value. Wheat flour products, maize, rice, beans, peas, lentil and soy from Vietnam and Hungary, furthermore several bakery products from Hungary and some imported soy products were analysed for phytate content. The effect of heat and fermentation on phytate content was also checked in breads and other foods. It was concluded that the processes often used in food industry, namely fermentation and thermal load, have relatively slight effect on the phytate content of plant foods. Cooking losses for phytates ranged 1-60% in cereals and legumes according to the usual kitchen technique in Vietnam.     

Phytase and Citric Acid Supplementation in Whole-Wheat Bread Improves Phytate-phosphorus Release and Iron Dialyzability

ABSTRACT Conditions were established for maximizing phytate breakdown in whole‐wheat flour (wwf) during bread baking and for assessing the effects of dephytinization on dialyzability of intrinsic and added iron in the bread. Three different sources of phytase (Aspergillus niger, A. fumigatus, and Escherichia coli) with various levels of citric acid (0 to 6.25 g/kg wwf) were used. Supplementing citric acid at 6.25 g/kg wwf enhanced phytate degradation catalyzed by intrinsic phytase from 42% in the untreated bread to 69% (P < 0.05). Supplementation of microbial phytase (285 units/kg) plus 3.125 or 6.25 g citric acid/kg wwf further enhanced phytate reduction up to 85%. Compared with the untreated bread, citric acid alone and the combination of citric acid and phytase enhanced total iron dialyzability by 12‐ and 15‐fold, respectively, while the combination of phytase, citric acid, and ascorbic acid improved total iron dialyzability in the mixture by 24‐fold.     

体外消化/Caco-2细胞模型分析发酵对面粉铁生物利用率的影响

中国居民膳食以谷物为主食,谷物中铁吸收率低是造成营养性贫血的主要原因,适当的加工方式可缓解谷物中植酸、多酚等物质对铁生物利用率(Fe bioavailability,FeBV)的影响。为考察酵母发酵对面粉FeBV的影响,采用体外消化/Caco-2细胞模型。结果表明,面团在发酵后pH值呈下降趋势,酸度呈上升趋势;多酚、植酸含量降低,植酸酶活性升高,以上各指标在发酵前后差异均具有统计学意义(P0.05)。发酵后面粉样品的FeBV增加约5%~38%,大多数面粉FeBV发酵前后比较,差异具有统计学意义(P0.05)。结论:发酵可降低面粉的pH值,增加酸度,有利于面粉多酚和植酸的降解以及植酸酶活力的升高,可有效提高面粉FeBV。     

Effect of malting and fermentation on antinutrients,and total and extractable minerals of high and low phytate corn genotypes

Two corn genotypes, Var‐113 (high phytate) and TL‐98B‐6225‐9 × TL617 (low phytate), were germinated for 6 days. The germinated grains were dried and milled. A mixture of 5% malt and 95% corn flour was fermented for 14 days. Phytic acid and polyphenol contents and hydrochloric acid (HCl) extractability of minerals from the fermented flours were determined at the intervals of 2 days during fermentation. Phytic acid and polyphenol contents decreased significantly (P ≤ 0.05) with an increase in fermentation time, with a concomitant increase in HCl‐extractable minerals. For both genotypes, the major mineral content was increased, while that of trace minerals was increased but at slow rate with fermentation time. When the grains were fermented for 14 days, TL‐98B‐6225‐9 × TL617 genotype had higher extractable calcium and Var‐113 had higher extractable phosphorus, whereas iron and manganese recorded high extractability levels in Var‐113. There was good correlation between phytate and polyphenol level reduction and the increment in extractable minerals with fermentation time.     

Calcium Additives and Sprouted Wheat Effects on Phytate Hydrolysis in Whole Wheat Bread

Whole wheat bread loaves were subjected to treatments of different fermentation periods, different sources and levels of calcium, and the addition of sprouted wheat. Phytate losses increased with increased fermentation time. Increasing the calcium level inhibited phytate hydrolysis when the calcium was provided by nonfat dry milk, CaCl₂, or nonfat yogurt, whereas phytate hydrolysis in loaves supplemented with CaCO₃ remained nearly constant. Milk-derived calcium exerted the greatest inhibition of phytate hydrolysis. The addition of sprouted wheat decreased absolute phytate losses. A comparison of phytate losses in yeasted vs nonyeasted loaves suggested that endogenous wheat phytase was quantitatively more important than yeast phytase during breadmaking.     

Sourdough fermentation of wheat fractions rich in fibres before their use in processed food

Fibre‐rich fractions of wheat are an important source of minerals but also contain considerable amounts of phytic acid, known to impair mineral absorption. This study explores the efficiency of wheat bran sourdough fermentation on phytate hydrolysis and mineral solubility, in comparison with whole‐wheat flour. In vitro trials were performed to assess the consequences of the addition of calcium carbonate (CaCO₃), an alkalinising salt, on phytic acid breakdown and mineral bioavailability during sourdough fermentation. Sourdough fermentation was found effective for solubilising minerals in whole‐wheat flours but was less effective with bran. In addition, sourdough acidity was blunted by the addition of CaCO₃, whereas degradation of phytic acid remained effective. Despite extensive breakdown of phytic acid (almost 70%), the addition of calcium exerted a very negative effect on zinc solubility. In conclusion, a pre‐fermentation process of whole cereals or bran, in suitable conditions of hydration, allows degradation of the major part of phytic acid and optimal mineral bioavailability. Copyright © 2007 Society of Chemical Industry     

Comparison of enhancement in bioaccessible iron and zinc in native and fortified high‐phytate oilseed and cereal composites by activating endogenous phytase

In developing countries, iron and zinc deficiencies are mostly attributable to poor bioavailability of iron and zinc. The study aimed at enhancing the bioaccessibility of minerals in high‐phytate oilseed and cereal flour mixes by activating the intrinsic phytase of wheat flour. The flour mixes were fortified with iron and zinc separately for comparison. The flour mixes were incubated at optimum conditions of temperature and pH for phytase activation. Phytase activation enhanced bioaccessible iron by 43–162% in native and 40–168% in fortified wheat–soya, 83–192% in native and 97–240% in fortified wheat–groundnut flour mixes in relation to control flour mixes. Bioaccessible zinc was enhanced by 87–183% in native and 30–113% in fortified wheat–soya, 31–65% in native and 61–186% in fortified wheat–groundnut flour mixes. Endogenous phytase activation was effective in enhancing bioaccessibility of iron and zinc in native and fortified flour composites economically.     

Application of Bifidobacteria as Starter Culture in Whole Wheat Sourdough Breadmaking

This investigation is aimed at developing a new cereal-based product, with increased nutritional quality, by using Bifidobacterium pseudocatenulatum ATCC 27919 as starter in whole wheat sourdough fermentation and evaluating its performance. Four different sourdough levels (5%, 10%, 15%, and 20% on flour basis) in bread dough formulation were analysed. The effects of the use of bifidobacteria in sourdough bread were comparatively evaluated with controls (yeast and/or chemically acidified sourdough with antibiotics). The sourdough and dough fermentative parameters analysed were pH, total titratable acidity, d/l-lactic and acetic acids. Bread performance was evaluated by specific volume, slice shape, crumb structure and firmness, crust and crumb colour, pH, total titratable acidity, and d/l-lactic and acetic acids, phytate, and lower myo-inositol phosphate contents. The sourdough breads showed similar technological quality to the control sample, with the exception of specific bread volume (decreased from 2.46 to 2.22 mL/g) and crumb firmness (increased from 2.61 to 3.18 N). Sourdough inoculated with bifidobacteria significantly increased the levels of organic acids in fermented dough and bread. The Bifidobacterium strain contributed to the fermentation process, increasing phytate hydrolysis during fermentation owing to the activation of endogenous cereal phytase and its own phytase, resulting in bread with significantly lower phytate levels (from 7.62 to 1.45 μmol/g of bread in dry matter). The inclusion of sourdough inoculated with bifidobacteria made possible the formulation of whole wheat bread with positive changes in starch thermal properties and a delay and decrease in amylopectin retrogradation.     

Zinc and iron contents and their bioaccessibility in cereals and pulses consumed in India

Several cereals and pulses commonly consumed in India were screened for zinc and iron contents and their bioaccessibility in the same was determined by equilibrium dialysis employing an in vitro simulated digestion procedure. Zinc content of cereals ranged from 1.08 mg/100 g in rice to 2.24 mg/100 g in sorghum. Zinc content of pulses was between 2.03 mg/100 g (whole chickpea) and 2.68 mg/ 100 g (decorticated chickpea). Iron content of cereals ranged from 1.32 mg% in rice to 6.51 mg% in sorghum, while that of pulses ranged from 3.85 mg% in decorticated green gram to 6.46 mg% in black gram. Dialyzability of zinc from pulses (27–56%) was generally higher than that from cereals (5.5–21.4%). Dialyzabilities of iron were almost similar from both cereals and pulses examined and were 4.13–8.05% in cereals and 1.77–10.2 % in pulses. A significant negative correlation between inherent phytate content and zinc dialyzability value was inferred in the case of pulses. Phytic acid content of the cereals had a significant negative influence on iron dialyzability. Inherent calcium had a negative influence on zinc dialyzability in cereals. Tannin did not have any significant influence on zinc or iron dialyzabilities from cereals and pulses. While both insoluble and soluble fractions of the dietary fibre generally interfered with zinc dialyzability, the insoluble fraction alone had this effect on iron dialyzability. The lower collective negative influence of the inherent factors on zinc dialyzability from pulses is consistent with their higher concentrations in these grains, relative to cereals. The negative correlation of inherent phytic acid with zinc and iron dialyzabilities was supported by enhanced dialyzabilities of these minerals upon partial removal of phytate from the grains by treatment with fungal phytase.     

双指标评价核桃蛋白酶法增溶改性

为了提高脱脂核桃粉中核桃蛋白的溶解性,文中以水解度(DH)和可溶性固形物(SS)含量为指标,分别对木瓜蛋白酶、菠萝蛋白酶和风味蛋白酶的单酶水解、复合酶解效果进行分析。结果显示,复合酶解可以显著提高核桃蛋白的溶解性,适宜的酶组合是:木瓜蛋白酶1.2%+菠萝蛋白酶0.4%+风味蛋白酶0.2%,底物浓度12%,60℃下酶解3 h。所得速溶核桃粉的DH为5.57%,SS为48.33%,其中蛋白质质量分数83.26%,吸水性和吸油性分别提高了68.99%和52.48%,达到了核桃蛋白的增溶目的。此外,分析结果表明,酶解过程中DH和SS间存在极显著相关性,说明SS可以作为蛋白质酶解效果的评价指标,与DH一起对核桃蛋白酶解效果进行准确评价。     

Removal of Phytate from Great Northern Beans (Phaseolus vulgaris L.) and Its Combined Density Fraction

The effect of pH on the dissociation of phytate complexes and subsequent removal of phytate from Great Northern bean (GNB) flour and its combined density fraction (CDF) was investigated. The largest amount of phytate removed was from GNB flour and CDF dispersions adjusted to pH 7.0 during dialysis. Dialyzed, unadjusted GNB flour and CDF respectively contained 55.4% and 59% of phytate in water-soluble form. The results indicate that phytic acid is present in GNB as a water soluble salt with a M.W. less than 1,000 daltons, water soluble complex with M.W. more than 1,000 daltons, and water insoluble complex. The presence of phytate in the CDF did not affect in vitro digestibility of CDF proteins.