Browning indicators in bread

Bread is the most important food in the Spanish household and represents the largest proportion of products produced by commercial bakeries. The browning indicators furosine, hydroxymethylfurfural (HMF), and color were determined to evaluate heat effects induced during manufacture of these foods. The breads analyzed were common, special, sliced toasted, and snack breads. Identical sample preparation and HPLC conditions were used to determine HMF in all breads. The precision tested at high and low HMF concentration in breads was 2.60% and 1.57%, respectively. Recovery of HMF was 96.2%. The HMF values ranged from 2.2 to 68.8 mg/kg. Color index (100 - L) ranged from 17.0 to 38.2. The linear correlations (r(2)) between 100 - L/HMF were above 0.70 for common, special, and snack breads. Similar correlation was obtained between 100 - L/HMF in a dough baking at different times. The furosine content in common bread ranged between 125 and 208 mg/100 g of protein. No linear correlation was found between furosine and HMF. Moreover, HMF and furosine were also determined in crumb and crust. Levels of HMF had a wide range (0.9-1.76 mg/kg) and furosine was between 43 and 221 mg/100 g of protein.     

Isotope labeling studies on the formation of multiple addition products of alanine in the pyrolysis residue of glucose/alanine mixtures by high-resolution ESI-TOF-MS

Pyrolysis was used as a microscale sample preparation tool to generate glucose/alanine reaction products to minimize the use of expensive labeled precursors in isotope labeling studies. The residue remaining after the pyrolysis at 250 °C was analyzed by electrospray time-of-flight mass spectrometry (ESI-TOF-MS). It was observed that a peak at m/z 199.1445 in the ESI-TOF-MS spectrum appeared only when the model system contained at least 2-fold excess alanine. The accurate mass determination indeed indicated the presence of two nitrogen atoms in the molecular formula (C(10)H(18)N(2)O(2)). To verify the origin of the carbon atoms in this unknown compound, model studies with [(13)U(6)]glucose, [(13)C-1]alanine, [(13)C-2]alanine, [(13)C-3]alanine, and [(15)N]alanine were also performed. Glucose furnished six carbon atoms, and alanine provides four carbon (2 × C-2 and 2 × C-3) and two nitrogen atoms. When commercially available fructosylalanine (N-attached to C-1) was reacted with only 1 mol of alanine, a peak at m/z 199.1445 was once again observed. In addition, when 3-deoxyglucosone (3-DG) was reacted with a 2-fold excess of alanine, a peak at m/z 199.1433 was also generated, confirming the points of attachment of the two amino acids at C-1 and C-2 atoms of 3-DG. These studies have indicated that amino acids can undergo multiple addition reactions with 1,2-dicarbonyl compounds such as 3-deoxyglucosone and eventually form a tetrahydropyrazine moiety.     

Improved method for the determination of hydroxymethylfurfural in baby foods using liquid chromatography-mass spectrometry

An improved analytical method for the rapid, reliable, and sensitive determination of hydroxymethylfurfural (HMF) in baby foods is described. It entailed aqueous extraction from food matrix with simultaneous clarification using Carrez I and II reagents, solid-phase extraction cleanup using Oasis HLB, and analysis by liquid chromatography-mass spectrometry. A narrow-bore column allowed fast chromatographic separation with good resolution of HMF and matrix coextractives. In positive atmospheric pressure chemical ionization conditions, precursor and compound-specific ions were sensitively detected in selected ion monitoring mode. Sample preparation with efficient cleanup followed by fast chromatographic analysis allowed the analysis to be completed in <20 min. Recovery ranged between 91.8 and 94.7% for spiking levels of 0.25, 1.0, and 5.0 mg/kg HMF in cereal-based baby foods. The method was shown to be successful when using liquid chromatography coupled to ultraviolet detection at 285 nm.     

Browning indicators in model systems and baby cereals.

In many countries, baby cereals are the first solid food given to 3-4-month-old babies after weaning and to infants aged 6-12 months. Various simple technologies are traditionally used in the processing of cereals, including toasting, hydrolysis, and drying. In this study color and hydroxymethylfurfural (HMF) assays have been used to evaluate heat effects induced during the manufacture of these foods. The baby cereals analyzed were wheat, rice, oat, and four mixtures of flours. No HMF was detected in the raw flours. Toasting the flours increased HMF values by between 1.1 and 4.53 mg/kg and color (DeltaE) values by 2.51-9.34. The drying step increased HMF values by between 1.14 and 19.60 mg/kg. High values of HMF coincided with the addition of ingredients containing HMF. Color and HMF contents in sugar-amino acid model systems were much higher than in sugar systems at temperatures >100 degrees C and low moisture content.     

Sterile solution culture techniques for aluminum toxicity studies involving organic acids

Microbial degradation of low molecular weight organic acids can be a serious source of error in solution culture experiments concerned with the protection of plant roots by these compounds against aluminum (Al) toxicity. Under normal glasshouse conditions, the problem was not solved by sterilisation of the various components of the solution culture system and surface sterilisation of the soybean and mungbean seeds. Of four water soluble antibiotics tested, streptomycin, rifampicin, and trimethoprim were phytotoxic at concentrations ≥ 50 mg/L; cefotaxime, while not phytotoxic up to 150 mg/L, gave poor control of microbial growth in 2‐day root elongation tests with mungbean. However, addition of 30 mg/L cefotaxime plus 20 mg/L trimethoprim at planting and a further 30 mg/L cefotaxime after one day was effective in controlling microbial numbers and preventing significant loss of added citrate to the solutions. At these concentrations the antibiotics were non‐phytotoxic and appeared not to cause any complexation of Al. Use of the method showed that citrate, L‐malate, and oxalate were highly effective detoxifiers of Al in solution.     

Heterocyclic volatiles formed by heating cysteine or hydrogen sulfide with 4-hydroxy-5-methyl-3(2H)-furanone at pH 6.5

The reaction of 4-hydroxy-5-methyl-3(2H)-furanone (HMF) with cysteine or hydrogen sulfide at pH 6.5 for 60 min at 140 degrees C produced complex mixtures of volatile compounds, the majority of these containing either sulfur or nitrogen. Of the 68 compounds detected, 63 were identified, some tentatively, by GC-MS. Among the identified compounds were thiophenes (10), thiophenones (6), thienothiophenes (5), thiazoles (5), trithiolanes (4), pyrazines (6), and oxazoles (4). More compounds were produced in the reaction of HMF with cysteine (63) than were formed in the reaction with hydrogen sulfide (33). In both systems, thiophenones were major reaction products, accounting for 25-36% of the total volatiles formed. Possible reasons for the differences in the composition of the two systems are discussed. The contributions of these reactions, and their products, to the flavor of heated foods are considered.     

Chemical composition of volatile extract and biological activities of volatile and less-volatile extracts of juniper berry (Juniperus drupacea L.) fruit

Volatile chemicals in a dichloromethane extract from a steam distillate of juniper berry fruit (Juniperus drupacea L.) and its two column chromatographic fractions (eluted with hexane and ethyl ether) were analyzed by gas chromatography/mass spectrometry. The major compounds in the dichloromethane extract were alpha-pinene (23.73%), thymol methyl ether (17.32%), and camphor (10.12%). A fraction eluted with hexane contained alpha-pinene (44.24%) as the major constituent. A fraction eluted with ethyl ether had thymol methyl ether (22.27%) and camphor (19.65%) as the main components. Three samples prepared from the distillate and two additional samples prepared by petroleum ether and ethanol extraction directly from juniper berry fruits exhibited clear antioxidant activities with dose response in both 1,2-diphenyl picrylhydrazyl and beta-carotene assays. All samples except the hexane fraction showed comparable activities to that of the synthetic antioxidant t-butyl hydroquinone at a level of 200 microg/mL in the two testing systems. The extracts of dichloromethane, petroleum ether, and ethanol exhibited appreciable antimicrobial activities against six microorganisms with minimum inhibitory concentrations ranging from 0.5 mg/mL (volatile extract against Candida albicans ) to 1.2 mg/mL (ethanol extract against Aspergillus niger ). The results of the present study suggest that this fruit could be a natural antioxidant supplement for foods and beverages.     

Investigation of the reaction between 4-hydroxy-5-methyl-3(2H)-furanone and cysteine or hydrogen sulfide at pH 4.5

Reaction of 4-hydroxy-5-methyl-3(2H)-furanone (HMF) with cysteine or hydrogen sulfide at pH 4.5 for 60 min at 140 degrees C produced complex mixtures of volatile compounds, the majority of which contained sulfur. Sixty-nine compounds were identified, some tentatively, by GC/MS. These included disulfides (26), thiols (7), dithiolanones (6), thiophenones (4), dithianones (3), and thienothiophenes (6). The main non-sulfur compounds were 2, 3-pentanedione, 2,4-pentanedione, and 3,4-hexanedione. Both systems produced approximately the same total quantity of volatile compounds, but the reaction containing cysteine gave the larger number of individual compounds, with thiols quantitatively the dominant components. By comparison, the major products formed in the reaction with hydrogen sulfide were the dithiolanones. Reaction pathways are presented for the major products and, where applicable, possible reasons for the differences in composition of the two systems are discussed. The contribution of these reactions, and their products, to the flavor of roasted foods is considered.     

Anti-inflammatory activity of an orange peel polymethoxylated flavone, 3',4',3,5,6,7,8-heptamethoxyflavone, in the rat carrageenan/paw edema and mouse lipopolysaccharide-challenge assays

The anti-inflammatory properties of 3',4',3,5,6,7,8-heptamethoxyflavone (HMF), a citrus polymethoxylated flavone, were studied in the bacterial lipopolysaccharide (LPS)-challenge/tumor necrosis factor-alpha (TNFalpha) response in mice and in the carrageenan/paw edema assay in rats. In each of these trials, HMF administered by intraperitoneal (ip) injection exhibited anti-inflammatory activity, whereas HMF administered orally (po) produced no effects. The inhibition observed in the LPS-challenge/TNFalpha assay correlated with the HMF levels in the blood sera of mice dosed (ip) with either 33 or 100 mg/kg body weight. Low levels of HMF (0.035 +/- 0.024 ppm) were detected in the blood sera of mice dosed orally [100 mg of HMF (suspended in vegetable oil)/kg], whereas ip injection led to higher levels (0.517 +/- 0.051 ppm). This may account for the different levels of anti-inflammatory effects observed in mice following ip vs oral HMF administration. HMF metabolites, including a number of mono- and di-demethylated HMF metabolites and their glucuronic acid conjugates, were also detected, but results of these studies suggest that the glucuronidated metabolites of HMF are inactive in these inflammation models.     

Spectrophotometric method for hydroxymethylfurfural in honey.

A new method is described for hydroxymethylfurfural (HMF) in honey; accuracy and precision are improved over the most used optical and chemical methods. With a clarified honey solution containing 0.1% sodium bisulfite as reference and a similar solution without bisulfite as sample, a difference spectrum is obtained which represents only the HMF in the sample, without the interfering absorption of the honey. The average recovery was 97.5% for 24 additions to honey of 0.8--40 mg HMF/100 g. Forty honey samples ranging from 0 to 40 mg/100 g were analyzed by 3 methods with the following average results: Winkler optical method, 7.25; Winkler chemical method, 4.83; and new bisulfite method, 5.05 mg HMF/100 g honey. Values by the latter 2 methods did not differ at the P = 0.05 significance level.     

Mumefural, citric acid derivative improving blood fluidity from fruit-juice concentrate of Japanese apricot (Prunus mume Sieb. et Zucc).

The effects of food components on blood fluidity were studied by in vitro assay using a dedicated microchannel instrument for model capillaries. We found that the fruit-juice concentrate of the Japanese apricot (Prunus mume Sieb. et Zucc), a traditional Japanese food, markedly improved the fluidity of human blood. Using HPLC, we isolated the active compounds and characterized them using UV, MS, IR, and NMR. They included a novel compound, 1-[5-(2-formylfuryl)methyl] dihydrogen 2-hydroxypropane-1,2, 3-tricarboxylate (mumefural), and a related compound, 5-hydroxymethyl-2-furfural (HMF). Mumefural markedly improved blood fluidity in all subjects, while HMF worked differently in different individuals. The flow rate of blood spiked with mumefural or HMF was compared to that of the two predominant organic acids in the fruit. Citric acid, malic acid, and furfuryl alcohol also improved fluidity in all subjects. The activity of P. mume is derived from not only artifacts produced during thermal processing, such as mumefural, but also from endogenous organic acids.     

Low-temperature brewing using yeast immobilized on dried figs

Dried figs, following exhaustive extraction of their residual sugars with water, were used for immobilization of Saccharomyces cerevisiae AXAZ-1. The immobilized biocatalyst was used in repeated batch fermentations of glucose at 30 degrees C, where significant reduction of the fermentation time was observed, falling from 65 h in the first batch to 7 h after the sixth batch. Repeated fermentations of wort at room and low temperatures resulted in fermentation times that fell from 26 to 20 h and from 27 to 24 days at 18 and 3 degrees C, respectively. Ethanol and beer productivities were high, showing suitability of the biocatalyst for low-temperature brewing. Diacetyl concentrations were low (0.3-0.5 mg/L), and polyphenols were lower than in commercial products and decreased as the fermentation temperature was decreased (126-50 mg/L). Ethyl acetate concentrations increased from 53 to 88 mg/L as the temperature was decreased, while the concentration of amyl alcohols at 3 degrees C (58 mg/L) was lower than half of that at 18 degrees C (125 mg/L). The beers produced at the end of the main fermentation had a fine clarity and a special fruity figlike aroma and taste, distinct from commercial products and more intense than beers produced by cells immobilized on other food-grade supports (gluten pellets or delignified cellulosic materials). GC-MS analysis did not show significant differences in the qualitative composition of the aroma compounds of the beers produced by immobilized and free cells.     

Levels of flavan-3-ols in French wines.

French wines are abundant sources of phenolic compounds. The content of several catechins, i.e., (+)-catechin, (-)-epicatechin, dimers B1, B2, B3, and B4, trimers C1, and trimer 2 (T2), of 160 French wines was determined by HPLC with UV detection. Red wines (n = 95) were found to have high levels of catechins, ranging from 32.8 to 209.8 mg/L (mean concentration 114.5 mg/L) for (+)-catechin, from 22.1 to 130.7 mg/L (mean concentration 75.7 mg/L) for (-)-epicatechin, from 7.8 to 39.1 mg/L (mean concentration 25.4 mg/L) for B1, from 18.3 to 93 mg/L (mean concentration 47.4 mg/L) for B2, from 21.4 to 215.6 mg/L (mean concentration 119.6 mg/L) for B3, from 20.2 to 107.2 mg/L (mean concentration 81.9 mg/l) for B4, from 8.6 to 36.9 mg/L (mean concentration 26.3 mg/L) for C1, and from 26.7 to 79.3 mg/L (mean concentration 67.1 mg/L) for T2. White and rosé wines (n = 57 and n = 8) were found to have low levels of (+)-catechin (mean concentrations 9.8 and 10.6 mg/L, respectively) and (-)-epicatechin (mean concentrations 5.3 and 6.5 mg/L, respectively). These data provide a basis for the epidemiological evaluation of catechin intake by the consumption of French wine.     

Liquid-liquid extraction for the enrichment of edible oils with phenols from olive leaf extracts

A liquid-liquid extraction method to enrich edible oils--olive, sunflower, and soy oils--with phenols from olive leaf extracts is proposed. After microwave assistance to remove the phenols from three varieties of olive leaves, concentrations in the extracts between 12921 and 5173 mg/L of oleuropein, between 488 and 192 mg/L of apigenin-7-glucoside, between 444 and 219 mg/L of luteolin-7-glucoside, and between 501 and 213 mg/L of verbascoside were obtained, which clearly depended on the target variety. After optimization of the liquid-liquid extraction step, the concentrations in oils were 442, 162, and 164 mg/L of oleuropein, respectively, which were also enriched in apigenin-7-glucoside (between 8 and 15 mg/L, depending of the oil), lutelin-7-glucoside (between 11 and 12 mg/L), and verbascoside (between 11 and 13 mg/L). The oil-extract distribution factor of these compounds was also calculated for all olive leaf varieties and edible oils using different extracts concentrations and also different oil-extract volume ratios. Thus, a door is open to enrichment of any oil with olive phenols at preset concentrations using extracts preconcentrated as required and taking into account the distribution factor of the target compounds between the oil and the extracts.     

Effects of thermal processing and storage on available lysine and furfural compounds contents of infant formulas

The Maillard reaction-related effects that thermal treatments during the manufacturing process and storage (at 20 and 37 degrees C) have on powdered adapted and follow-up milk-based infant formulas were estimated by measuring the available lysine and furfural compounds contents of raw cow milk used in manufacturing, intermediate products and formulas. A fluorimetric method was used to measure the available lysine contents, and free and total furfural compounds were determined by HPLC. Statistically significant losses in available lysine (about 20%) in the infant formulas with respect to raw milk were found. The storage period did not affect the available lysine contents of adapted formulas but reduced (16%) the contents of the follow-up ones (from 6.61 to 5.33 g/100 g of protein). No furfural compounds were detected in raw milk, and free and total furyl methyl ketone (FMC) and methylfurfural (MF) were not observed in the analyzed samples. After 6 months of storage, an increase in free hydroxymethylfurfural (HMF) (from 0.34 to 0.77 mg/100 g of protein) and furfural (F) (from nondetectable to 0.1 mg/100 g of protein) in adapted formulas and free HMF (from 1.84 to 2.62 mg/100 g of protein) in follow-up formulas was observed.     

Tocopherol and tocotrienol levels of foods consumed in Hawaii

Because of the individual biological effects and the uncertain or missing information on levels of tocopherols (T) and tocotrienols (T3) in foods frequently consumed in Hawaii, 79 food items (50 in duplicate) were analyzed for alpha-, beta-, gamma-, and delta-tocopherol (alphaT, betaT, gammaT, and deltaT) and alpha-, beta-, gamma-, and delta-tocotrienol (alphaT3, betaT3, gammaT3, and deltaT3) in addition to alpha-tocopheryl acetate (alphaTac). Foods from local markets were stored according to usual household habits, freeze-dried, homogenized, and extracted three times with hexane containing butylated hydroxytoluene as a preservative and tocol as an internal standard. A normal-phase high-pressure liquid chromatography system was applied with fluorescence and photodiode array detection that resulted in baseline separation of all eight analytes and the internal standard tocol (To). The sum of all E vitamer concentrations, or total E vitamers (TEV), in all foods analyzed ranged an average from 0.6 to 828 mg/kg (T < or = 542 mg/kg and T3 < or = 432 mg/kg) and showed the following ranges: oils, 497-828 mg/kg (mainly alphaT and gammaT); margarines, 359-457 mg/kg (mainly gammaT); salad dressings, 20-291 mg/kg (mainly gammaT, except alphaT when soy oil was the main ingredient); cookies, 54-138 mg/kg (mainly gammaT); snacks, 101-220 mg/kg (mainly gammaT); nuts, 22-201 mg/kg (mainly alphaT); vegetables, 2-152 mg/kg (mainly alphaT); pasta, 24-90 mg/kg; cereals, 4-56 mg/kg (mainly betaT3 followed by alphaT); fish, 2-39 mg/kg (mainly alphaT); fried tofu, 64 mg/kg (mainly gammaT); breads, 20-22 mg/kg (mainly betaT3); fat-free mayonnaise, 5 mg/kg (mainly alphaT); poi (fermented taro root), 2 mg/kg (mostly alphaT); and fruits, 2 (papaya) to 13 mg/kg (canned pumpkin) with alphaT predominating. Cereals fortified with alphaTac ranked third and eighth among all foods assayed regarding alphaT and TEV levels, respectively. As compared to the few data available in the literature, our values agreed with some (corn flakes, mango fruit, fat-free mayonnaise, dry-roasted macadamia nuts, dry-roasted peanuts, mixed nuts, spaghetti/marinara pasta sauce, oils, and red bell pepper) but differed for many other items. Our results provide new information on the E vitamer content in foods, emphasize the vast differences of bioactivities of individual E vitamers, and confirm the need for analyses of foods consumed in specific study populations.     

平阳霉素对花生体细胞胚胎发生的影响

本文对花生离体培养高频率体细胞胚(体胚)诱导方法,及平阳霉素(PYM)对体胚发生的抑制作用进行了研究,旨在为以PYM作为化学诱变剂进行花生离体诱变提供有效方法.以花生品种花育20号和花育22号成熟种子的胚小叶为外植体,在添加不同浓度2,4-D(0,5,10,15,20mg/L)的MSB5(MS无机盐+B5有机成分)培养...     

赤霉素对盐害下碱茅的萌发和幼苗生长的影响

以碱茅为试材,在100 mmol/L的NaCl盐胁迫下,通过种子培养、室内盆栽试验,研究盐胁迫下不同浓度赤霉素（8,15,20,25,50 mg/L）对碱茅种子萌发、幼苗生长的影响。结果表明:（1）100 mmol/L的NaCl严重抑制碱茅的种子萌发和幼苗生长,碱茅种子的发芽率、发芽势和发芽指数、根茎长显著降低,根系活力、过氧化物酶活力受到严重抑制;（2）在外源赤霉素溶液为8～20 mg/L的范围内,随着浓度的升高,碱茅种子的发芽率、发芽势和发芽指数、根茎长逐渐升高,根系活力、过氧化物酶活力、耐盐指数明显提高;（3）高浓度（ > 20 mg/L）的外源赤霉素浸种处理,对种子的促进作用逐渐下降,当赤霉素浓度为50 mg/L时,碱茅的发芽率和根茎比低于对照,产生了抑制效应。结论:不同浓度赤霉素对提高碱茅种子耐盐性有不同程度的促进作用,以赤霉素浓度为20 mg/L时作用效果最佳。     

Cultivation of the Indian fig Opuntia in selenium-rich drainage sediments under field conditions

Growing selenium (Se)-biofortified alternative crops in saline and Se-contaminated agricultural land in arid/semi-arid regions, such as the western United States, depends upon the plant’s ability to tolerate high salinity and accumulate Se. In this field study, we evaluated the ability of five prickly pear cactus clones [Opuntia ficus-indica (L.) Mill., no. 243, 248, 250, 252, and 255] to grow, accumulate and volatilize Se from drainage sediment high in sulphate salinity (∼5 dS/m), soluble B (∼5 mg/L) and Se concentrations (∼0.8 mg/L). After 3 years of growth, all clones exhibited significant decreases up to 20% in height and fruit production compared with control clones. Mean Se concentrations (mg/kg DM) ranged from 4.9 to 9.8 in cladodes, 1.5–2.5 in fruit flesh, and 4.5–10.1 in seeds. Rates of Se volatilization varied from 20 to 80 μg Se/m² per day among the tested clones. The successful growth of prickly pear cactus and its accumulation and volatilization of Se under adverse soil conditions may provide growers with an alternative Se-biofortified crop in the westside of the San Joaquin Valley in central California.     

Oxalate and phytate of soy foods

The consumption of foods made from soybeans is increasing because of their desirable nutritional value. However, some soy foods contain high concentrations of oxalate and/or phytate. Oxalate is a component of calcium oxalate kidney stones, whereas phytate is an inhibitor of calcium kidney stone formation. Thirty tested commercial soy foods exhibited ranges of 0.02-2.06 mg oxalate/g and 0.80-18.79 mg phytate/g. Commercial soy foods contained 2-58 mg of total oxalate per serving and 76-528 mg phytate per serving. Eighteen of 19 tofu brands and two soymilk brands contained less than 10 mg oxalate per serving, defined as a low oxalate food. Soy flour, textured vegetable soy protein, vegetable soybeans, soy nuts, tempeh, and soynut butter exhibited greater than 10 mg per serving. The correlation between oxalate and phytate in the soy foods was significant (r = 0.71, P < 0.001) indicating that oxalate-rich soy foods also contain higher concentrations of phytate. There also was a significant correlation, based on molar basis, between the divalent ion binding potential of oxalate plus phytate and calcium plus magnesium (r = 0.90, P < 0.001) in soy foods. Soy foods containing small concentrations of oxalate and moderate concentrations of phytate may be advantageous for kidney stone patients or persons with a high risk of kidney stones.