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1.
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.  相似文献   

2.
The effect of pH and calcium (Ca) on the dissolution of Gafsa (GPR) and Christmas Island A (CIPR) phosphate rocks (PR) was examined in closedincubation and open-leaching systems in six acid, Malaysian soils. The pH of the soils was increased to between 4.5 and 6.1 by incubating with calcium carbonate (CaCO3); soil was also incubated with calcium chloride (CaCl2) to provide equivalent amounts of Ca without causing any marked change in pH. In the closed-incubation system, dissolution of reactive GPR was overall higher (11–70%) than for the less reactive CIPR (12–43%) after 60 days of incubation. Dissolution of PR decreased with increasing levels of CaCO3 or CaCl2, but the decrease was more pronounced in CaCO3-treated than in CaCl2-treated soils. Increasing additions of CaCl2 decreased the size of the available sink for Ca from 84.0 to 0 mmol (+) kg–1 soil. Although the addition of CaCO3 increased the cation-exchange capacity (CEC) of these variable-charge soils (from 23.0 to 199.0 mmol (+) kg–1 soil), most of the newly-created exchange sites were occupied by Ca added through CaCO3. This was responsible for the decrease in size of the sink for Ca. Addition of CaCO3 also decreased the proton supply from 260.7 to 0 mmol (+) kg–1 soil, which in conjunction with the decrease in size of the Ca sink decreased the dissolution of PR. The effect of CaCO3 and CaCl2 on PR dissolution varied between soils and was related to pH-buffering and the Ca-sink size. In an open-leaching system, large amounts of Ca (8–40%) added as CaCO3 were removed in the leachate and hence the decrease in GPR dissolution with CaCO3 addition was less in the open-leaching than in the closed-incubation system.  相似文献   

3.
An in vitro sequential pH treatment, simulating the gastrointestinal tract, was used to evaluate effects of Zn fortification, source of Ca and milk type (skim, 1 and 2% fat, homogenized and unhomogenized whole) on Ca, Fe and Zn solubility in moderately (MF) and highly fortified (HF) whole wheat cereals. In both cereals, soluble Zn significantly increased in response to fortification level. While CaCO3-supplemented skim milk promoted mineral solubility in all MF systems, whole milk was most effective in the HF systems. This effect was apparently related to % milkfat and the homogenization process.  相似文献   

4.
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  相似文献   

5.
Sodium phytate was added to milk with and without the addition of Fe or Zn and the solubility of the endogenous Ca and added Fe or Zn was not affected. However, when these experiments were repeated with a model system containing CaCl2 at the same calcium concentration as milk, the addition of Na phytate caused a significant precipitation of each of these minerals. These results suggest that milk exerts a protective effect on the phytate induced precipitation of these minerals and thus their potential bioavailability.  相似文献   

6.
In order to investigate possible interactions of phytate with protein and minerals in simplified animal diets, studies were conducted on the solubility of endogenous phytate, protein and essential minerals in a soybean–maize meal blend within a physiological relevant pH range. The blend was mixed with water for 10 min and then allowed to incubate at 40 °C (30 min) after adjustment of the pH. Finally, soluble phytate, protein, zinc, manganese and iron were determined. Phytate and mineral solubility was highly influenced by pH whereas protein solubility was less affected. Addition of 5 g Ca2+ kg?1 drastically reduced the solubility of phytate, zinc, manganese and iron at pH above 4.4, indicating that the formation of insoluble phytate–mineral complexes is increased in the presence of calcium. The action of pepsin increased the solubility of protein and phytate at pH below 4, indicating that insoluble phytate–protein complexes are present at low pH. Calcium had the same solubilising effect as pepsin at pH 2–4 but to a lesser degree. Copyright © 2007 Society of Chemical Industry  相似文献   

7.
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  相似文献   

8.
The probiotic Lactobacillus acidophilus was encapsulated in biodegradable and biocompatible capsules prepared by ionic gelation between phytic acid (PA) and chitosan (CS) with an electrostatic extrusion method. Calcium carbonate (CaCO3) and starch were used as co‐encapsulants for improvement of capsule stability. Capsules were characterised and evaluated for survival of encapsulated L. acidophilus cells in simulated gastric fluid (SGF) and during refrigerated storage. Loading capacity values of PA‐CS capsules, PA‐CS‐starch capsules and PA‐CS‐CaCO3 capsules were 8.20, 8.12 and 7.81 log CFU g?1 of wet capsule, respectively. Capsules showed particle sizes of 1.3–1.5 mm and a uniform spherical shape. PA‐CS‐CaCO3 capsules were the most stable vehicles for the protection of probiotic cells against acidic damage, particularly at pH 1.5 and pH 2. L. acidophilus cells from PA‐CS‐CaCO3 capsules showed only a 0.64 log CFU reduction in numbers after 2 h in pH 1.5 SGF conditions. The numbers of L. acidophilus encapsulated in PA‐CS‐CaCO3 capsules were decreased by only 0.69 log CFU g?1, while PA‐CS capsules and PA‐CS‐starch capsule numbers were reduced by more than 1.45 log CFU g?1 after 4 weeks at 4 °C. Addition of calcium carbonate to PA‐CS capsules provided protection against acid injury via antacid and buffering effects for encapsulation of L. acidophilus.  相似文献   

9.
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.  相似文献   

10.
This study focussed on the impact of process variables on levels of phytate and phenolic compounds, and in vitro solubility of iron (Fe) and zinc (Zn) in sorghum porridges, a major staple in semi‐arid tropics. The aim was to identify practices that enhance the mineral availability in this type of staple food. We studied the example of the West African porridge ‘dibou’ for which the processing methods involve grain cleaning, milling, sieving and cooking. Regional variations occur in the process, particularly in the cleaning which may be done wet or dry; sieving may be omitted in certain locations. Cleaning reduced the phytate content of the grain by 24–39%, while milling, sieving and cooking had no significant effect on phytate. Phenolic compounds measured as levels of reactive hydroxyl groups, remained constant after cleaning, milling and sieving, but significantly decreased by 38–65% after cooking. The Fe solubility tended to increase after cleaning but was drastically reduced due to cooking, and so was the soluble Zn. Levels of total phenolic compounds highly correlated with the Fe and Zn solubility (r2 = 0.73 and 0.82, respectively). Phenolic reaction products formed during the cooking process are presumably related with the extensive browning phenomenon observed in the dibou porridge, and with the reduction observed in Fe and Zn solubility. Copyright © 2007 Society of Chemical Industry  相似文献   

11.
Calcium bioavailability from legumes containing a range in trypsin inhibitor activity (TIA) and tannin concentration was studied. Three cultivars (Phaseolus vulgaris) were hydroponically grown and intrinsically labeled with 4SCa. Raw and cooked legumes were fed to six groups of 6-wk old male Sprague-Dawley rats. Another group received an intraperitoneal (IP) injection of 45Ca. An eighth group was fed a casein metal extrinsically labeled with 45Ca. The absorption of calcium from legumes by rats averaged 47.1 ± 7.5% of IP dose. Average phytate content of the legumes was 1.7% and oxalate 0.37%. Raw legumes had an average of 15000 TIA units/g of whole bean, which were completely removed by cooking. Calcium absorption was unaffected by TIA or tannin content. Reduced availability of bean calcium was likely due to phytate and/or oxalate present in legumes.  相似文献   

12.
Whey fractions cor taining proteins (albumins), phytate, and minerals were prepared from black gram (Phaseolus mungo L.) cotyledons and were employee to study the interactions between protein, phytate, and minerals at pH 2.80, 6.40, and 8.40. Black gram cotyledons contained 1.7% phytate, of which 88.7% existed in watersoluble form. Phytate phosphorus represented for about 89% of total phosphorus in black gram cotyledons. Recovery of phytate in fraction I (pH 2.80), fraction II (pH 8.40), and fraction III (pH 6.40) was 45%, 69%, and 4%, respectively, after 48 hr dialysis. At pH 2.80, complexation occurred between phytate and proteins. Complexation between phytate and proteins at pH 8.40 was mediated by divalent cations such as calcium, magnesium, and zinc. Fraction II had higher concentrations of divalent cations (calcium, magnesium, and zir c) than the other two fractions I and III.  相似文献   

13.
The effect of phytate on the solubility of Al3+ and Pb2 + has been investigated in vitro at 37°C across the pH ranges 3–7 (Pb2+) and 2–5 (Al3+). For both ions minimum solubility was found when the initial metal ion: phytate ratio was in the range 5:1–3:1 across the whole pH range. For Al3+ the solubility rose sharply either side of these ratios whereas for Pb2 + solubility rose only slowly as the metal ion: phytate ratio was reduced. Hg2+ was totally soluble under all conditions tested. At pH 7 Ca2+ solubility was found to be at a minimum when the initial Ca : phytate ratio was 5 :1 irrespective of the initial Ca2+ concentration.  相似文献   

14.
Pita bread loaves were prepared from flours fortified with calcium carbonate, calcium sulfate, and tricalcium dicitrate at 8 ascending levels to provide ranges of 800 to 2500, 700 to 1500, and 400 to 2000 mg of added Ca/100 g flour, respectively. The detection thresholds of calcium salts in pita bread were determined by the 3‐alter‐native forced choice (3‐AFC) test and construction of dose‐response curves. Detection thresholds determined by calculating geometric mean of individual best estimate thresholds, using criterion of 50%‐above‐chance and probit analysis of 3‐AFC data, were in the middle region of calcium concentrations. Analysis of dose‐response curves yielded values for thresholds outside the range of surveyed calcium concentrations. The detection threshold of CaSO4 (2724 mg/100 g) in pita bread was significantly higher (P < 0.01) than those of calcium carbonate (1984 mg/100 g) and tricalcium dicitrate (2132 mg/100 g). Calcium‐fortified pita bread was similar (P < 0.01) to its regular counterpart when formulated to contain 1254.6, 1772.5, or 1155 mg/100 g of CaCO3, CaSO4, or tricalcium dicitrate, respectively. At the indicated levels of fortification, calcium‐fortified pita bread is expected to provide between 61% and 126.5% of the recommended daily intake for calcium for Middle Eastern populations.  相似文献   

15.
Kinetic properties and thermal inactivation of pectinlyase (PL) were assayed in commercial pectinase preparations (Rapidase C80, Pectinase CCM, Pectinex 3XL and Grindamyl 3PA) by using apple pectin as substrate. The PL activity of Rapidase C80 showed substrate inhibition, while the other enzyme preparations followed typical Michaelis–Menten kinetics. The optimum pH and temperature values for PL activity lay within the range of 5.5–6.5 and 35–40 °C, respectively. PL was heat‐inactivated with simple first order kinetics. With respect to this, thermodynamic activation parameters (ΔH#, ΔS# and ΔG#) using a non‐linear Arrhenius plot were calculated. The Pectinase CCM and Pectinex 3XL PL showed a half‐life (t1/2) at 50 °C of 2.0 min and 11.8 min, respectively.  相似文献   

16.
Unintentional movement of P from dairy cow manure to off-farm locations has been an environmental concern for some time. The objective of this study was to evaluate the effects of increasing the dietary concentration and solubility of Ca and the dietary concentration of Mg on lactation performance and solubility of fecal P from lactating dairy cows receiving diets formulated to the same concentration of P (0.38% of dry matter). Eight dietary treatments were evaluated in a 2 × 2 × 2 factorial arrangement involving 2 dietary sources of Ca (CaCO3 having a moderate solubility of Ca vs. CaCl2 having an excellent solubility of Ca) and 2 dietary concentrations of Ca (average of 0.64 and 0.95% of dry matter) and Mg (0.25 and 0.4% of dry matter). Twenty-four multiparous cows in mid lactation were fed the 8 diets in three 21-d periods. Dry matter intake and milk production were measured daily, and milk composition was measured on the last 6 milkings of each period. Fecal samples were collected twice a day during the last 5 d of each period, composited within cow, dried at 55°C, and subjected to 10 successive water extractions, and soluble P, Ca, and Mg were determined. Excretion of fecal P (g/d) was correlated positively with intake of P but not with intake of Ca or Mg. A smaller proportion of fecal P was extracted when dietary concentration of Ca increased (37.5 vs. 47.7%) and when CaCl2 instead of CaCO3 was fed (40.3 vs. 44.9%). Feeding more Mg reduced water-soluble P in feces but only when CaCO3 and not CaCl2 was fed. Increasing the amount of soluble Ca in the diet produced a relatively stable Ca-phosphate compound (hydroxylapatite) in ashed fecal samples, whereas feeding less soluble Ca resulted in a more soluble P phase (Mg-substituted whitlockite). Energy-dispersive X-ray elemental spectroscopy in conjunction with scanning electron microscopy showed spatial association between Ca-Mg and P. A reduction of approximately 5 g of soluble P/cow per d was detected when dietary concentration of Ca increased from an average of 0.64 to 0.95% of dry matter. Supplemental CaCO3 would be a preferred source of Ca over CaCl2 because cows fed CaCO3 tended to produce more 4% fat-corrected milk, more milk fat, and milk with a greater concentration of fat and protein. Current prices would also favor feeding CaCO3 over CaCl2. Increasing dietary intakes of Ca and Mg beyond current recommendations may increase formation of insoluble phosphate complexes (Ca-P rather than Ca-Mg-P associations), which result in decreased solubility of P in dairy-cow feces and reduce losses of P from agricultural areas where feces are applied.  相似文献   

17.
The effects of proportion of concentrate in the ruminant diet and the effects of freezing ruminal content prior to assay on proteolytic activity in ruminal inoculum were evaluated using three analytical techniques. A novel approach for determining proteolytic activity (PA) of ruminal fluid utilising 15N‐labelled casein was compared with two published procedures. In a crossover experiment, four heifers were fed two isonitrogenous diets containing (dry matter basis) 50% barley silage, 45% rolled barley grain and 4% soybean meal (medium‐grain diet, MG) or 8% barley silage, 89% rolled barley grain and 2% soybean meal (high‐grain diet, HG). Ruminal fluid was analysed either fresh or after having been frozen at ?40 °C for 45 days. Substrates utilised in measuring PA included 15N‐labelled casein (produced by infusing (15NH)2SO4 into the rumen of a lactating dairy cow), 14C‐labelled casein and azocasein. Incubations were conducted in 0.2 M phosphate buffer (pH 6.8) for 20 min at 39 °C. In the 15N‐casein incubations, PA was estimated as (i) N soluble in 5% trichloroacetic acid (TCASN), (ii) N soluble in 5% TCA corrected for microbial N uptake (TCAMICR) and (iii) N depleted from the soluble protein N pool (SPR). In the 14C‐casein incubations, PA was measured as TCA‐soluble radioactivity; in the azocasein method it was measured as dye released during incubation. Across treatments the highest (P < 0.001) proteolytic activity was measured by the SPR method, followed by TCAMICR, TCASN and 14C‐casein. The lowest activity was recorded using the azocasein method. Within the 15N‐ and 14C‐casein methods, PA in previously frozen ruminal fluid was higher (P < 0.05) with the HG diet than with the MG diet, and higher (P < 0.05) in previously frozen fluid than in inoculum processed fresh. This study demonstrates that increasing the proportion of grain in the diets of cattle and freezing the ruminal inoculum both increase proteolytic activity measured in ruminal fluid. The proposed 15N‐casein method yielded higher proteolytic activity values than the 14C‐casein method. Copyright © 2002 Society of Chemical Industry. Contributions of A N Hristov, T A McAllister and Z Xu. © Minister of Public Works and Government Services, Canada 2002.  相似文献   

18.
A.P.P. Kayodé  M.J.R. Nout 《LWT》2007,40(5):834-841
Opaque sorghum beer is a significant component of the diet of millions of poor people in rural Africa. This study reports the effect of traditional brewing operations on its level of micronutrients, especially iron and zinc. The example of a West African sorghum beer, tchoukoutou, in Northern Benin was studied. The beer was characterized and the impact of process unit operations on phytate, phenolic compounds, and Zn and Fe in vitro solubility was evaluated. The major microorganisms involved in the beer fermentation were Saccharomyces cerevisiae and heterofermentative lactobacilli. The manufacturing process reduces the phytate content by nearly 95%, particularly during germination, mashing-boiling and fermentation. The level of reactive phenolic groups increased as a result of germination and fermentation as well as from a shift in dry matter composition. Simultaneously with these modifications, an increase of Fe solubility was observed, and a correlation between phytate and Fe solubility (R2=0.85) was established. No clear correlation could be established between the Zn solubility and the phytate content of the products. During beer manufacturing, significant losses of minerals occur particularly during soaking and mashing/filtration; thus the quantity of minerals available to consumers is restricted. Improvements aiming to minimize such losses are highly desirable.  相似文献   

19.
A commercial soybean isolate was phosphorylated using casein kinase II purified from the yeast Yarrowia lipolytica. Both major reserve proteins, β‐conglycinin and glycinin, were phosphorylated in a sequential way. The soybean isolate incorporated up to 0.7 mol phosphate per mole in 2 h. It was found that the phosphoester bonds were stable over time. The solubility of the phosphorylated isolate with respect to pH was not dramatically increased in comparison with the native one. However, counting the radioactivity of 32P incorporated into the proteins (only the solubility of the phosphorylated proteins was measured in this case) showed that the solubility of the proteins was dramatically improved (up to 90% solubility for phosphorylated β‐conglycinin at pH 4). β‐Conglycinin became more soluble in the presence of CaCl2 upon phosphorylation; this was not the case for the isolate. The iron‐binding capacity of the soy isolate and β‐conglycinin was significantly improved after phosphorylation (two and six times respectively). © 1999 Society of Chemical Industry  相似文献   

20.
Condiments produced from some underutilized legumes in Nigeria were evaluated for their nutritional and sensory qualities. Soybeans (Glycine max), locust beans (Parkia filicoidea L.), pigeon pea (Cajanus cajan) and melon seed (Citrullus lunatus) were subjected to solid substrate fermentation and their proximate composition, mineral, antinutrient and the organoleptic properties were subsequently determined. The result of the study revealed that the condiments had high protein (17.8 [pigeon pea] to 44.6% [soybean]), fat (11.8 [pigeon pea] to 21.0% [soybean]), ash (1.9 [melon] to 4. 7% [pigeon pea]) and crude fiber (5.9 [soybean] to 11.2% [pigeon pea]). The macroelements (K, Ca, Mg and Na) were generally high while the microelements (Fe and Zn) content was low. The phytate content of the condiments ranged from 187.8 (pigeon pea) to 921.2 mg/100 g (soybeans), while the tannin content ranged from 1.8 (pigeon pea) to 2.9 mg/g (melon seed). The calculated [phytate]/[Zn] (0.3–1.3), [Ca]/[phytate] (3.6–66.6) and [Ca][phytate]/[Zn] (0.02–0.06) molar ratios revealed that the phytate content did not reduce the estimated Zn bioavailability in the condiments to a critical level. However, the condiments had lower general acceptability when compared with monosodium glutamate‐based seasoning salt. In view of the high nutrient content these condiments produced from underutilized legumes, they could be a good alternative to the monosodium glutamate‐based seasoning salts presently in use. The condiments produced from soybean and locust beans appear to be more promising than those from pigeon pea and melon seed based on nutrition and sensory acceptability.  相似文献   

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