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1.
Over the past two decades, the role of folate in human nutrition has been of much interest because of its relationship to diseases such as neural tube defects and heart disease. Since 1998, the U.S. Food and Drug Administration has mandated that cereal products be fortified with 140 microg of folic acid/100 g. It is important, therefore, to be able to determine accurately the folate concentrations in cereals and other grains to ensure proper dietary intake of folate. In this study, a microbiological method employing a trienzyme extraction procedure was applied to the analysis of folate in several starchy grain legumes (pulses). Differences in the folate content of dry bean were observed among some market classes but not between cultivars in the same market class. Location had a significant effect on the folate content of lentil and dry pea; cultivar did not. The significant effect of market class, cultivar, and growth environment on the levels of folate in pulses is of particular importance to pulse processors and pulse breeders.  相似文献   

2.
Response surface methodology was applied to optimize the trienzyme digestion for the extraction of folate from vegetables. Trienzyme extraction is a combined enzymatic digestion by protease, alpha-amylase, and conjugase (gamma-glutamyl hydrolase) to liberate the carbohydrate and protein-bound folates from food matrices for total folate analysis. It is the extraction method used in AOAC Official Method 2004.05 for assay of total folate in cereal grain products. Certified reference material (CRM) 485 mixed vegetables was used to represent the matrix of vegetables. Regression and ridge analysis were performed by statistical analysis software. The predicted second-order polynomial model was adequate (R2 = 0.947), without significant lack of fit (p > 0.1). Both protease and alpha-amylase have significant effects on the extraction. Ridge analysis gave an optimum trienzyme digestion time: Pronase, 1.5 h; alpha-amylase, 1.5 h; and conjugase, 3 h. The experimental value for CRM 485 under this optimum digestion was close to the predicted value from the model, confirming the validity and adequacy of the model. The optimized trienzyme digestion condition was applied to five vegetables and yielded higher folate levels than the trienzyme digestion parameters employed in AOAC Official Method 2004.05.  相似文献   

3.
Bread flour was spiked with folic acid (1.40 mg/lb or 3.08 μg/g of flour) and processed into bread by the sponge and dough method. Changes that occurred to added folic acid and endogenous folate contents through different processing stages, including sponge formation, proofing, and baking, were assessed by reversed‐phase ion‐pair HPLC combined with UV and fluorometric detection. Sample extraction required α‐amylase and rat plasma deconjugase digestion, and sample preparation required purification by solid‐phase extraction. Added folic acid was measured by monitoring UV absorption at 280 nm. Four selected forms of endogenous folates including tetrahydrofolate (THF), 5‐formyl‐THF, 10‐formylfolate, and 5‐methyl‐THF were identified and quantified throughout the bread processing using a fluorescence excitation wavelength of 290 nm and emission wavelength of 350 or 450 nm. Data indicate a relatively good stability of added folic acid and native folates to the baking process, and increased endogenous folate contents in dough and bread as compared with the flour from which they were made.  相似文献   

4.
Determination of niacin in fortified infant and dairy products has been accomplished using a variety of analytical liquid chromatography (LC) methods. Applications of these LC techniques to other food matrices suffer due to the presence of endogenous absorbing peaks at 260 nm that co‐chromatograph with the nicotinic acid and nicotinamide vitamers. We have successfully adapted the LC method of Woollard and Indyk for the determination of nicotinamide in reference and commercial cereal products. Unbound nicotinamide in fortified cereal was extracted with 0.6M tri‐chloroacetic acid and chromatographed on a C18 reversed‐phase column using a mobile phase of 75% methanol and water (pH 2.8, with formic acid) with sodium dioctylsulphosuccinate (0.1%) as the ion‐pairing agent. Using Spectral Analysis ChromQuest software, a three‐dimensional view showed only nicotinamide under the LC peak. Similarity index spectral matches of nicotinamide standard and the LC peak were ≈100%, indicating the absence of interferences. Nicotinamide recoveries for the reference cereals of VMA195 and VMA 399 (from AACC International, St. Paul, MN) and GM 19B (from General Mills, Medallion Laboratories, Minneapolis, MN) were 90–103% of assigned value. Experimental values for oat, corn, rice, and bran cereals showed that actual niacin content in commercial cereals may be significantly above (111–170%) declared label values. Because manufacturers may fortify at a level higher than the declared label level to ensure shelf life compliance, these data do have significant implications when making precise estimates of niacin intake based on label claims.  相似文献   

5.
A dual label stable isotope dilution assay was developed to trace the deconjugation efficiency of polyglutamic folate vitamers converted to their monoglutamic analogues. For this purpose, [(13)C(5)]-pteroylheptaglutamate was synthesized and added during extraction of foods as a tracer isotopologue along with [(2)H(4)]-5-methyltetrahydrofolate, [(2)H(4)]-5-formyltetrahydrofolate, [(2)H(4)]-tetrahydrofolate, [(2)H(4)]-10-formylfolate, and [(2)H(4)]-folic acid. The [(2)H(4)]-labeled folates were used as internal standards for the monoglutamates. Deconjugation converted the addition tracer [(13)C(5)]-pteroylheptaglutamate to the detection tracer [(13)C(5)]-folic acid, which was quantified along with unlabeled folic acid using [(2)H(4)]-folic acid as the internal standard. LC-MS/MS enabled the unequivocal differentiation of the three isotopologues. This tracing was used to optimize deconjugation efficiency, which was achieved by using 4-morpholineethanesulfonic acid buffer for extraction at pH 5.0 . The optimized assay revealed limits of detection for the folate vitamers ranging between 2.0 and 5.6 pmol per assay (equivalent to 2.2-6.6 μg/100 g dry mass), recoveries ranging between 98 and 105% and relative standard deviations in inter-assay precision ranging between 2 and 6%. The assay was applied to quantitate folates in spinach, beans, cheeses, bread, wheat germs, and yeast .  相似文献   

6.
Degradation of added folic acid and native folates in micronutrient‐fortified corn masa and tortillas was evaluated using masa prepared from either nixtamalized corn flour or fresh nixtamal. Variations in masa pH, masa holding time at an elevated temperature, and iron source failed to show significant differences in folate loss in corn flour masa prepared in the laboratory. Masa was subsequently prepared from fresh nixtamal in a commercial mill in Mexico, and fortified with one of two different micronutrient premixes containing iron, zinc, B‐vitamins, and either unencapsulated or lipid‐encapsulated folic acid. Folate loss in commercial masa increased significantly with prebake masa holding time for both premixes. Unencapsulated folic acid showed a 73% loss after 4 hr of holding, compared to 60% loss for encapsulated. The difference was statistically significant, indicating a protective effect from the lipid coating. No significant differences in folate levels were found between prebake masa and baked tortillas. Holding baked tortillas for up to 12 hr also had no effect on folate levels. Native folate showed no significant losses throughout the process. Results from the commercial tortilla mill indicate that most of the loss in added folic acid occurs during prebake holding of masa, possibly from microbial degradation.  相似文献   

7.
The effect of baking method on folates of rye and wheat breads, as well as the effect of sourdough fermentation of rye, were examined. Sourdough fermentations were performed both with and without added yeast, and samples were taken throughout the baking process. Samples were analyzed microbiologically for their total folate content after trienzyme extraction. Individual folate vitamers were determined by HPLC after affinity chromatographic purification. The lowest folate contents for both rye and wheat breads were found from breads baked without added yeast. Total folate content increased considerably during sourdough fermentation due to increased amounts of 10‐HCO‐H2folate, 5‐CH3‐H4folate, and 5‐HCO‐H4folate. Baker's yeast contributed markedly to the final folate content of bread by synthesizing folates during fermentation. Proofing did not influence total folate content but changes in vitamer distribution were observed. Folate losses in baking were ≈25%. The variety of sourdoughs and baking processes obviously lead to great variation in folate content of rye breads. The possibilities to enhance natural folate content of rye bread by improving folate retention in technological processes and by screening and combining suitable yeasts and lactic acid bacteria should be further investigated.  相似文献   

8.
A trienzyme treatment (protease, alpha-amylase, and human plasma conjugase), followed by purification using SPE with SAX cartridges and reversed-phase HPLC with UV-PDA detection, was performed for determination of the distribution of various folate forms and content at various stages of tempe preparation. The major folate form in soybean identified was 5-formyl tetrahydrofolate (5-CHO-H4folate), followed by 10-formyl tetrahydrofolate (10-CHO-PGA), and 5-methyl tetrahydrofolate (5-CH3-H4folate), whereas folic acid was not detected and tetrahydrofolic acid (H4folate) was not detectable. The most predominant form in tempe was also 5-CHO-H4folate, followed by 10-CHO-PGA, whereas the quantities of 5-CH3-H4folate and folic acid were negligible. Quantities and retention of folate significantly decreased during the first boiling, dehulling, soaking, and second boiling procedures, yielding folate retention of 32%. A remarkable increase in folate content was found after fermentation, 5.2-fold higher than that of the boiled soybean. This may be due to de novo formation of folate by Rhizopus oligosporus, the principal mold in tempe fermentation. HPLC results were approximately 38-55% lower than the values obtained from the microbiological assay using Lactobacillus casei.  相似文献   

9.
OBJECTIVES: The introduction of voluntary fortification of some foods with folic acid in Australia has been implemented since evidence of the prevention of neural tube defects with periconceptional folic acid was published. Our objectives were to determine how many women were aware of folate and when they became aware, what was the awareness of labels on foods that mentioned folate, and how much folate-fortified food women ate. METHODS: To address these objectives we collected data by self-administered questionnaire from a random sample of 578 recently pregnant women in Western Australia between September 1997 and March 2000. RESULTS: Overall, 89% of women had heard, seen or read anything about the link between folate and birth defects such as spina bifida, 62% first became aware of the folate message before their recent pregnancy and 42% of women noticed any labels on foods that mention folate before or during their recent pregnancy. Overall, 53% of women were aware of foods that have folate added to them and 33% usually or always read the labels on food packaging. The folate-fortified foods most often consumed by women were cereals (69%), breads (34%) and milk (15%). Of the women who consumed folate-fortified foods (78%), the earlier they became aware of the folate message and noticed labels on food, the more fortified foods they consumed. CONCLUSIONS: These results indicate that staple foods fortified with folate are consumed by almost 80% of women in the population. Therefore, mandatory fortification of staple foods may reach most women, providing improved opportunity for the prevention of neural tube defects in Australia.  相似文献   

10.
A method based on a gel permeation chromatography (GPC) extraction procedure combined with an additional cleanup by solid-phase extraction (SPE) on silica gel and liquid chromatography-mass spectrometry (LC-MS) detection has been validated for the analysis of seven glycidyl esters (GEs) including glycidyl laurate, myristate, palmitate, stearate, oleate, linoleate, and linolenate in various edible oils. This method was conjointly developed and validated by two different laboratories, using two different detection systems, a LC time of flight MS (LC-ToF-MS) and a LC triple-quadrupole MS (LC-MS/MS). The extraction procedure allowed targeting low contamination levels due to a highly efficient matrix removal from the 400 mg oil sample loaded on the GPC column and is suitable for routine analysis as 24 samples can be extracted in an automated and reproducible way every 12 h. GPC extraction combined with SPE cleanup and LC-MS/MS detection leads to a limit of quantification in oil samples between 50 and 100 μg/kg depending on the type of glycidyl ester. Recoveries ranged from 68 to 111% (average = 93%). Quantification was performed by automated standard addition on extracts to compensate matrix effects artifacts. To control recoveries of each sample four isotopically labeled GEs ((13)C(3) or (13)C(4)) were included in the method.  相似文献   

11.
《Cereal Chemistry》2017,94(6):917-921
Neural tube defects occur at higher rates in Hispanic populations in the United States. Such populations would benefit from folic acid fortification of corn masa flour (CMF). This study evaluated folate stability in fortified CMFs and tortillas and tortilla chips made therefrom. There was no significant loss of folate during the six‐month shelf life of fortified tortilla CMF and tortilla chip CMF. There was a 13% loss (P < 0.05) of folate during tortilla baking and no loss during tortilla chip frying. Both tortillas and tortilla chips showed significant folate losses over the two‐month shelf life for these products, with a 17% loss in fortified tortillas and a 9% loss in tortilla chips. Folate in fortified CMFs, tortillas, and tortilla chips is relatively stable and comparable to the stability of folate in wheat flour and breads.  相似文献   

12.
The practice of food fortification with folic acid offers the potential to increase the folate intake of the general population. To fully exploit the potential of fortification for raising folate nutriture, appropriate food vehicles need to be selected. Selection should involve determination of the availability of folic acid as affected by characteristics of the carrier food, food matrix, food preparation, and cooking. The present study investigated the effects of preparation and cooking of a range of folic acid-fortified foods on the folate status of folate-deficient rats. Fifty-six weanling male rats (Wistar strain) were fed a folate-deficient diet containing 1% succinyl sulfathiazole for 28 days. Following depletion, six rats were randomly assigned to each of eight repletion diets containing cooked or uncooked meringue mix, quick bread mix, brownie mix, or pizza base mix. The test foods were fortified with 1400 microg of folic acid/kg of food and incorporated as 19% of the repletion diets. Each of the first four groups was pair-fed a diet containing a cooked fortified food with another group fed the corresponding uncooked fortified food. After a further 28 days, plasma, liver, and kidney folate concentrations were determined by microbiological assay. Mean plasma and liver folate concentrations of rats fed diets containing cooked fortified foods were similar to those of rats fed uncooked fortified foods. Preparation and cooking did not affect the availability of folic acid from the selected cereal-based convenience foods in this rat model system, suggesting that these foods are appropriate vehicles for fortification with folic acid.  相似文献   

13.
The impact of extrusion on physical and sensory properties and on the in vitro bile acid (BA) binding was examined for N979 and Jim oat (Avena sativa) lines with 8.1 and 4.8% β‐glucan, respectively. Based on hardness and edibility of products made from Jim oats, moisture concentrations of 16–25% and temperatures of 165–180°C were selected for N979 extrusion. Jim‐based cereal had a significantly greater (P < 0.05) expansion ratio than did N979‐based cereal at most moistures. N979 cereal was browner, but not harder, than Jim cereal. Extruded products from N979 and Jim oats had 5.29–5.99% and 3.38–3.94% β‐glucan, respectively. Changing extrusion temperature or moisture content did not affect β‐glucan concentration in the products. N979 cereal made at 165°C and 16% moisture had greater BA binding than at other conditions, and had crunchiness comparable to cereals made at other conditions. BA binding of Cheerios brand breakfast cereal was close to that of N979 cereal made at 180°C and 18% moisture, but lower than cereals made at other conditions. Cereals made from Jim and N979 oats were browner, harder, coarser, and crunchier than Cheerios breakfast cereal. Proper processing and preparation techniques should be considered when producing extruded products from high β‐glucan oats.  相似文献   

14.
Lignans are of increasing interest because of their potential anticarcinogenic, antioxidant, estrogenic, and antiestrogenic activities. In this work, mixed‐cereal pastas manufactured by adding 60% whole‐grain flours of different cereals (wheat, oat, rye, barley, and rice) to durum wheat semolina, a multigrain pasta with different grains (cereals, legumes, and flaxseed), and a traditional industrial durum wheat semolina were analyzed for their lignans content both in the raw and in the cooked state, ready for consumption. For raw mixed‐cereal pastas, total lignans were within the range 94.91–485.62 μg/100 g d.w. After cooking, total lignans losses of about 35.5, 18.31, and 5.46% were observed respectively in oat‐, rye‐, and rice‐added pastas, whereas increases of 5.74 and 13.62% were observed in barley‐added and whole durum wheat pastas. Interesting results were obtained for the multigrain pasta: the raw product exhibited a total lignans content of 9,686.17 ± 287.03 μg/100 g d.w., and the major contribution was given by secoisolariciresinol. This highest total lignans value resulted from its rich and varied composition in seeds of different origin, legumes, and flaxseed in particular. Our findings showed that mixed‐cereal and multigrain pastas can be considered a good source of lignans. The effect of cooking was not the same for each product, and it depended on the different lignans profile of each grain, on the different chemical structure of each lignan, and on the nature of the food matrix.  相似文献   

15.
Brown rice flour was mixed with a Chinese medical plant (Euryale ferox Salisb.) and processed to make ready‐to‐eat breakfast cereals using twin‐screw extrusion. Levels of 15 and 20% feed moisture in flour, and 200 and 250 rpm screw speed were set, and the physicochemical properties and content of α‐, β‐, γ‐, and δ‐tocopherols were determined. The data showed that 15% feed moisture gave a low bulk density and water absorption index but a high expansion ratio and water solubility index. High screw speed (250 rpm) produced a result similar to that of 15% feed moisture. A sample with 85% brown rice flour with 15% E. ferox Salisb. retained the highest content of α‐, β‐, γ‐, and δ‐tocopherols (125, 6, 78, and 9 μg/g), respectively. The optimum extrusion conditions determined were 15% E. ferox Salisb. mixed with brown rice at 15% feed moisture and at 250 rpm screw speed.  相似文献   

16.
True ileal total lysine digestibility was determined and compared with true ileal reactive lysine digestibility when applied to 20 cereal-based breakfast foods. Semisynthetic diets each containing a breakfast cereal as the sole protein source were formulated and fed to growing rats. Titanium dioxide was included as an indigestible marker. Digesta were collected from the rats and total (conventional amino acid analysis) and reactive (guanidination) lysine were determined in both diets and digesta. The true ileal reactive lysine digestibility ranged from 53 to 108% and was significantly higher than the true ileal total lysine digestibility for most of the breakfast cereals. Available lysine content (digestible reactive lysine content) ranged from 0.21 to 3.5 g/kg across the breakfast cereals. The conventional measure of digestible total lysine content significantly overestimated (on average 37%) available lysine for the majority of the cereals. Breakfast cereals undergo a significant degree of lysine modification probably as a result of processing during manufacture.  相似文献   

17.
Vertical distribution and plant availability of soil P under subsurface irrigation were investigated in a 5‐year tomato‐grown‐greenhouse experiment. Irrigation was applied when soil water condition reached the predefined maximum allowable depletion (MAD) for different treatments, e.g., –10 kPa, –16 kPa, –25 kPa, –40 kPa, and –63 kPa. Results show that P distribution with soil depth was significantly affected by irrigation schedules. The general trend is that concentrations of soil total P and inorganic P were greater in topsoil than in subsoil, whereas the concentrations of soil organic P were larger at the depths of 0–10 cm, 30–40 cm, and 40–60 cm than at other soil depths. Comparison of different irrigation schedules indicates that more soil organic P was retained in the soils under the MAD of –25 kPa, –40 kPa, and –63 kPa, implying that irrigation of relatively low frequency and large water quantity of each irrigation event favored the accumulation of organic P in soils. In addition, we found that the concentrations of plant‐available P decreased with soil depth and were largest under the MAD of –16 kPa and –25 kPa. This result suggests that irrigation of relatively high frequency and low water quantity of each irrigation event led to greater P availability for plant uptake. Overall, this study suggests that the transformation and plant availability of soil P can be manipulated, to some degree, by soil‐water management. Maximum allowable depletion controlled between –16 kPa and –25 kPa could result in high availability of soil P in clay‐textured soils.  相似文献   

18.
A stable-isotope liquid chromatography-mass spectrometry (LC-MS) assay was developed for the quantitative determination of folic acid in fortified foods. Folic acid was extracted from food samples into a phosphate buffer, purified on a C-18 Sep-Pak cartridge, and analyzed by LC-MS in the negative ion mode using electrospray ionization. The analyte was quantified using (13)C(5)-folic acid as an internal standard. The coefficient of variation for the precision of the method was 5.6% based on the analysis of four sample replicates. The accuracy of the method was assessed using a standard method of addition of folic acid to a shredded whole-wheat cereal. The quantitative determination of folic acid in this matrix was linear over 1 order of magnitude having a concentration range of 2.4 to 24 microg/g of food (or 0.05 to 0.5 microg of analyte injected into the LC-MS). The overall quantitative efficiency of the method was evaluated using a standard reference material (infant formula SRM 1846). The method was applied to the determination of folic acid in several test samples (fortified breakfast cereals), and the values were in accord with the manufacturer's claim. This method advances a LC-MS technique for the determination of folic acid in fortified foods based on stable-isotope dilution methodology. The specificity of the technique and quantitative accuracy of the method in various food substrates suggests that the method may be adapted for routine analysis in other fortified foods.  相似文献   

19.
An extremely sensitive method for the analysis of 2‐acetyl‐1‐pyrroline (2AP) in rice, employing stir bar sorptive extraction (Twister) was studied. The Twister stir bar is placed in the headspace of a 20‐mL vial containing 1 g of rice kernels, 7.5 mL of 0.1M KOH, and 2.2 g of NaCl, along with a second Teflon‐coated stir bar for mixing. Analytes are adsorbed onto the Twister for 4 hr at 40°C and then desorbed at 270°C into a GC column while cryofocusing at –80°C. The headspace sorptive extraction (HSSE) method was able to detect <0.1 ppb of 2AP in rice. The precision of the HSSE method (>10%) was not as good as the GC/FID method (≈6%). Using HSSE, 2AP was observed in all samples generally considered to be aromatic and was not observed in any nonaromatic samples. Additionally, a modified method for the synthesis of 2‐acetyl‐1‐pyrroline was studied and the presence of a tautomer of 2‐acetyl‐1‐pyrroline was confirmed.  相似文献   

20.
BACKGROUND: Observational studies and clinical trials have shown conclusive evidence that periconceptional folic acid supplementation prevents up to 70 % of neural tube defects (NTD). The Honduran government wanted to implement a supplementation programme of folic acid but needed to assess the relative effects of two dosages of folic acid. OBJECTIVE: To determine the effect of two dosages of folic acid on blood folate levels in Honduran female factory workers aged 18 to 49 years. DESIGN: This was a randomized, double-blind control supplementation trial conducted in Choloma, Honduras. A total of 140 eligible women were randomly assigned to two dosage groups and followed up for 12 weeks. One group received a daily dosage of 1 mg folic acid and the other a once weekly dosage of 5 mg. Serum folate and red blood cell folate levels were determined by radioassay at baseline, 6 weeks and 12 weeks. RESULTS: Serum folate levels increased from 6.3 (se 0.2) to 14.9 (se 0.6) ng/ml (P < 0.0001) in women assigned to the 1 mg/d group and from 6.9 (se 0.3) to 10.1 (se 0.4) ng/ml (P < 0.0001) in those assigned to the 5 mg/week group. Red blood cell folate concentrations also increased significantly in both groups, albeit more slowly. Educational level, age and BMI were not associated with the changes in serum and red blood cell folate levels during the supplementation period. However, a differential effect on serum folate levels by dosage group and time was observed. CONCLUSIONS: Although both folate supplementation regimens increased serum and red blood cell folate levels significantly among the women studied, blood folate levels that are considered to be protective of NTD were reached faster with the daily dosage of 1 mg folic acid.  相似文献   

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