Gamma-oryzanol content,phenolic acid profiles and antioxidant activity of rice milling fractions

This study was aimed to determine γ-oryzanol content and total phenolics, individual phenolic acid profile and the antioxidant activity of the free and bound extracts of rice milling fractions namely, brown rice, unpolished rice, white rice, chalky rice, raw seed and rice bran. Gamma-oryzanol content of milling fractions which is designated with a simple chromatographic method was in the range of 12.19–3,296.5 mg/kg. The whitening and polishing steps reduced approximately 94% of γ-oryzanol of the brown rice when becoming the white rice. The contribution of bound phenolics to the total phenolic content was approximately 40%. Ferulic and p-coumaric acids were the most abundant phenolic acids in bound phenolic extracts and their amounts were 119.98 and 18.10 μg/g, respectively, in rice bran. The best source of γ-oryzanol, phenolics and antioxidants was clearly rice bran and followed by raw seed and brown rice.     

Antioxidants in milling fractions of black rice cultivars

Coloured rice, particularly black rice, has been shown to possess bioactive properties, and rice bran contains high levels of several antioxidant compounds. The aim of this study was to quantify the major antioxidant compounds in the milling fractions of black rice. Whole black rice of two cultivars (Oryza sativa cv. Heugjinjubyeo and O. sativa L. Heugkwangbyeo) was milled into rice bran and endosperm using the gradual milling system (85% milling degree). Relatively high levels of free polyphenols and flavonoids from two cultivars were found in the bran fractions (98.5 and 81.0 mg of polyphenols and 19.8 and 15.1 mg of flavonoids) while low levels were found in endosperm fractions. Compared to free polyphenols and flavonoids, low levels of bound polyphenols and flavonoids were found in all fractions. The black rice bran contained most of the antioxidant compounds, including phytic acid, γ-oryzanol, anthocyanins, and vitamin E homologues.     

Distribution of aflatoxins in shelling and milling fractions of naturally contaminated rice

The objective of this study was to determine the distribution of an economically important class of mycotoxins, the aflatoxins, in rice milling fractions. Rice plants grown under field production conditions are frequently infected with types of pathogenic fungi that produce toxic metabolites (mycotoxins). Paddy (seeds) rice from healthy plants in the field was collected and stored on a farm under humid, poorly ventilated conditions. Samples were milled into four fractions (hulls, brown rice, bran and white rice) and analysed for aflatoxins (B(1), B(2), G(1) and G(2)) using a validated method. Rice fractions from healthy plants, which contained low levels of aflatoxins (less than 1?μg?kg(-1)), were used to determine the efficiency of the extraction method. Seeds stored under poor conditions were found to be contaminated with aflatoxins B(1) and B(2) as were the fractions. The sums of AFB(1) and AFB(2) in stored paddy rice, hulls, brown rice, bran and white rice were 141, 39, 158, 367 and 56?μg?kg(-1), respectively. The ratio of aflatoxin B(1) and B(2) was about 10?:?1. AFG(1) and AFG(2) were less than 1?μg?kg(-1). Thus, brown rice contained 92.9% of the aflatoxins in paddy rice, whereas white rice contained only 27.9%.     

Distribution of aflatoxins in shelling and milling fractions of naturally contaminated rice

The objective of this study was to determine the distribution of an economically important class of mycotoxins, the aflatoxins, in rice milling fractions. Rice plants grown under field production conditions are frequently infected with types of pathogenic fungi that produce toxic metabolites (mycotoxins). Paddy (seeds) rice from healthy plants in the field was collected and stored on a farm under humid, poorly ventilated conditions. Samples were milled into four fractions (hulls, brown rice, bran and white rice) and analysed for aflatoxins (B₁, B₂, G₁ and G₂) using a validated method. Rice fractions from healthy plants, which contained low levels of aflatoxins (less than 1?µg?kg^?1), were used to determine the efficiency of the extraction method. Seeds stored under poor conditions were found to be contaminated with aflatoxins B₁ and B₂ as were the fractions. The sums of AFB₁ and AFB₂ in stored paddy rice, hulls, brown rice, bran and white rice were 141, 39, 158, 367 and 56?µg?kg^?1, respectively. The ratio of aflatoxin B₁ and B₂ was about 10?:?1. AFG₁ and AFG₂ were less than 1?µg?kg^?1. Thus, brown rice contained 92.9% of the aflatoxins in paddy rice, whereas white rice contained only 27.9%.     

Selenium content of goat milk and its distribution in protein fractions.

This study reports on selenium distribution in goat milk. Skim milk was found to contain the major part (94%) of total milk selenium. The selenium distribution over casein and whey protein fractions depends on the separation method used, but irrespective of these methods, skim milk selenium is mainly associated with the casein fraction (greater than 69%). Approximately 9%, 7% and 24% of selenium is removed by dialysis (molecular cutoff 10-12 kDa) from skim milk, casein and whey respectively, indicating a major association of selenium with milk proteins. This observation is confirmed by selenium analysis of individual caseins and whey proteins isolated through ion-exchange chromatography and gel filtration. Selenium concentrations of the different isolated milk proteins show considerable variation (caseins: 294-550 ng Se/g; whey proteins: 217-457 ng Se/g).     

稻谷在加工过程中无机砷含量的分布情况

目的 测定糙米、大米及糠粉中无机砷的含量,研究无机砷在稻米中的分布情况.方法 随机抽取20份稻谷样本,经实验室垄谷和碾米后得到的糙米、大米及糠粉.使用液相色谱-原子荧光联用仪检测所得糙米、大米及糠粉中的无机砷含量.结果 样本中的砷主要以亚砷酸根[As(Ⅲ)]的形式存在.糙米中的亚砷酸根[As(Ⅲ)]含量为(0.122±...     

Phytate and mineral content in different milling fractions of some Pakistani spring wheats

Six Pakistani wheat cultivars, namely C-273, Inqulab-91, Pasban-90, Parwaz-94, Shahkar-95 and Rohtas-90, were included in the present study. The kernel weight of the wheat cultivars varied from 31.43 to 36.76 g (per thousand kernels), Parwaz-94 having the highest and Rohtas-90 having the lowest. The test weight of cultivars ranged from 70.23 (Shakar-95) to 76.13 kg hL^–1 (Pasban-90). The bran contained the highest amount of phytic acid (6.12%) in C-273 followed by whole-wheat flour (2.23%) in Inqulab-91, and straight-grade flour (0.24%) in Parwaz-94. The phytate content was reduced during the baking of bread and chapati. The bread scores and other quality characteristics varied significantly among cultivars. The total bread scores ranged from 35.20 to 42.00, out of a possible fifty, with Parwaz-94 being the highest. The concentration of minerals varied widely in different milling fractions of various wheat cultivars. The concentration of Cu, Fe, Mn and Zn ranged from 5.00 to 52.50, 26 to 147.50, 0.00 to 97.00, 9.0 to 80.80 ppm, respectively, in different milling fractions of the wheat cultivars. The total chapati scores ranged from 22.40 to 24.20 of a possible score of 30. The minimum chapati scores were found in Rohtas-90 and Parwaz-94, while Inqulab-91 produced the maximum score.     

Genetic dissection of amino acid content in rice grain

BACKGROUND: Protein content and amino acid composition in rice are the most important components of rice nutrient quality. However, there have been few reports on the mapping of quantitative trait loci (QTLs) for the contents of protein and amino acids in rice grain and other crops (soybean, corn). In this study a population of 241 recombinant inbred lines (RILs) from a cross between Zhenshan 97 and Minghui 63 (the parents of the most widely grown hybrid rice in China) was constructed to detect the main effect and epistatic effect QTLs for amino acid content (AAC) as characterised by individual AACs, total essential AAC and total AAC. RESULTS: Using a linkage map covering a total of 1796 centimorgan (cM) based on 221 molecular marker loci, a total of 12 QTLs were identified for ten traits mapped on chromosomes 1, 4, 6, 7 and 11. The QTL cluster (flanked by C904, R2632 and C39) on chromosome 1 was associated with the content of eight amino acids. The phenotypic variation explained by individual QTLs ranged from 3.4 to 48.8%. Eighty‐one digenic interactions were resolved that involved 143 loci distributed on all 12 chromosomes. The amount of variation explained by main effect QTLs was lower than that explained by QTLs involved in epistatic interactions. CONCLUSION: The findings showed that most main effect QTLs for AACs detected tended to be co‐localised within the genome. Thus, if a breeder were interested in changing the concentration of only one amino acid, this might be difficult to achieve. Meanwhile, the prevalent epistasis for the loci involved appeared to hold true for the content of amino acids. The information reported in the present study is expected to be useful for future breeding programmes targeting the development of improved rice amino acid composition for human nutrition. Copyright © 2009 Society of Chemical Industry     

Changes in the cadmium content of rice during the milling process

Milled rice and bran were prepared from brown rice (Oryza sativa japonica) using a commercial scale rice-mill to investigate the changes in cadmium (Cd) content caused by the milling process. Rice sample solution was prepared by microwave digestion using HNO3 and HF, then analyzed by ICP-MS. Cd was measured at m/z 114 in interference correction with MoO and Sn. The digestion method was validated with 4 kinds of certified reference material of "rice flour". We found that the Cd content was reduced only slightly by the milling process. When the Cd concentration of brown rice was regarded as 100, the relative content of the milled rice was 97 (average of 6 samples). In addition, the reduction of the Cd content was only slight when milled rice was processed to "wash-free" rice. The relative Cd content of the bran was 139 when that of brown rice was regarded as 100. These results support the hypothesis that the Cd content is not greatly decreased by the milling process.     

Impact of durum wheat milling on deoxynivalenol distribution in the outcoming fractions

The milling behaviour of two naturally infected samples of durum wheat grain with contrasting levels of mycotoxins was studied. Although the two samples showed a similar milling behaviour, an increase of ～20% in deoxynivalenol (DON) levels was found in semolina from the sample containing the higher level of mycotoxin. However, even if the highest concentration of DON was found in fractions originating from the grain outer layers, the mycotoxin contamination in semolina and flours were not related to the amount of two compounds (ash or phytic acid) used to monitor these external tissues. The presence of the trichothecene-producing fungi in the inner-most semolina fraction was also shown using specific DNA primers and PCR amplification. Comparison of DON concentrations in the feed stock and corresponding output at each milling step or grinding of semolina fractions followed by sizing showed that concentration of mycotoxin occurs in the finest particles at the first processing steps. Therefore, DON contamination of milling fractions is not simply due to the presence of peripheral grain tissues.     

Selenium content of goat milk and its distribution in protein fractions

Summary This study reports on selenium distribution in goat milk. Skim milk was found to contain the major part (94%) of total milk selenium. The selenium distribution over casein and whey protein fractions depends on the separation method used, but irrespective of these methods, skim milk selenium is mainly associated with the casein fraction (> 69%). Approximately 9%, 7% and 24% of selenium is removed by dialysis (molecular cutoff 10–12 kDa) from skim milk, casein and whey respectively, indicating a major association of selenium with milk proteins. This observation is confirmed by selenium analysis of individual caseins and whey proteins isolated through ion-exchange chromatography and gel filtration. Selenium concentrations of the different isolated milk proteins show considerable variation (caseins: 294–550 ng Se/g; whey proteins: 217–457 ng Se/g).

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Der Selengehalt von Ziegenmilch und seine Verteilung in den Proteinfraktionen

Zusammenfassung Diese Studie bespricht die Selen-Verteilung in Ziegenmilch. Magermilch enthält 94% des gesamten Selens der Milch. Die Selen-Verteilung ist abhängig von der Technik des Abtrennens des Caseins von den Molkenproteinen, aber ungeachtet dessen befindet sich das Selen der Magermilch hauptsächlich in der Casein-Fraktion (>69%). Ungefähr 9% bzw. 7% bzw. 24% des Selens wurden aus Magermilch bzw. Casein bzw. Molke durch Dialyse (molekulare Ausschaltung 10–12 kDa) entfernt, was auf eine Assoziation des Selens mit den Milchproteinen hinweist. Dies wurde bestätigt durch die Selenanalyse des durch Ionenaustauschchromatographie bzw. Gelfiltration isolierten Caseins und der Molkeproteine. Der Selengehalt der verschiedenen isolierten Milchproteine zeigt bemerkenswerte Differenzen (Caseine: 294–550 ng Se/g; Molkeproteinen: 217–457 ng Se/g).

     

Selenium content of sheep's milk and its distribution in protein fractions

The selenium (Se) distribution in sheep's milk is reported. Skim milk was found to contain the major part (98%) of total milk Se. The Se distribution over casein and whey protein fractions depends on the separation method used, but irrespective of these methods, skim milk Se is mainly associated with the casein fraction (>68%). Approximately 11%, 4% and 17% Se is removed by dialysis (molecular mass cut-off 10–12 kDa) from skim milk, casein and whey respectively, indicating a major association of Se with milk proteins. This observation is confirmed through Se analysis of individual caseins and whey proteins isolated through ion-exchange chromatography and gel filtration. Se concentrations of the different isolated milk proteins show considerable variations (caseins, 304–750 ng Se/g; whey proteins, 241–806 ng Se/g).

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Der Selengehalt von Schafsmilch und seine Verteilung in den Proteinfraktionen

Zusammenfassung Diese Studie bespricht die Selen-Verteilung in Schafsmilch. Magermilch enthält 98% des gesamten Se der Milch. Die Se-Verteilung ist abhängig von der Trennungstechnik bei der Abscheidung des Caseins und der Molkenproteine. Das Selen befindet sich in der Magermilch, hauptsächlich in der Casein-Fraktion (>68%). Ungefähr 11% bzw. 4% bzw. 17% des Se wurden aus Magermilch bzw. Casein bzw. Molke durch Dialyse (molekulare Ausschaltung 10–12 kDa) entfernt, was auf eine Assoziation von Se mit den Milchproteinen hinweist. Dies wird bestätigt durch eine spezielle Se-analyse des Caseins und den Molkeproteinen mit Hilfe der Ionen-austauschchromatographie bzw. Gelfiltration. Der Segehalt der isolierten Milchproteine zeigt bemerkenswerte Unterschiede: Casein: 304–750 ng Se/g; Molkenproteine: 241–806 ng Se/g.

     

Folate in oats and its milling fractions

Total folate content in oat varieties from three harvesting years (2006-2008), and in oats milling fractions, was determined using microbiological assay. Furthermore, folate vitamer distribution in milling fractions were examined with the UPLC method, which was taken in use and validated. The total folate content of the cultivars varied moderately within each year. The average content in the 2008 samples was 685ng/gdm. The UPLC method proved fast and sensitive for determining seven folate monoglutamates in cereal samples. Folate content in fractions, which are normally discarded, such as flour from oat cutting and flaking, were 1.5- to 2.5-fold higher than in native grain. The main folate vitamers found in the oat fractions were 5-CH(3)-H(4)folate, 5-HCO-H(4)folate, and 5,10-CH(+)-H(4)folate. The UPLC results more closely matched the microbiological results compared to those that are usually achieved with HPLC methods. This study illustrates that oats and, especially, by-products of milling are good sources of folate.     

Strikingly high content of grain protein in solution‐cultured rice

A greenhouse experiment was conducted to investigate the nutritional quality of solution‐cultured rice. Five rice cultivars, different in grain amylose content and protein content, were grown under 10, 40 and 80 mg l^?1 nitrogen levels during the period of July 2003 to October 2003. In comparison to their original seeds, the solution‐cultured rice Oryza sativa L grain had strikingly higher protein content across all the cultivars and nitrogen levels, and remarkably lower amylose content in the waxy and low amylose cultivars, which might be due to the sufficiently stable nitrogen supply and well‐controlled temperature and humidity. The highest grain protein content was 163.6 g kg^?1 in this experiment, which is the highest reported rice grain protein content. The residual nitrogen concentration was greater than 12.39 g kg^?1 in the roots, 8.95 g kg^?1 in the stems, and 21.97 g kg^?1 in the flag leaves across all the cultivars and nitrogen treatments at harvesting. The rice grain had a narrow range of grain carbon content and hydrogen content. The average grain carbon and hydrogen contents for all the rice samples were 42.95 ± 0.15 (n = 60) and 6.81 ± 0.04 g kg^?1 (n = 60), respectively. The solution cultured rice grain was characterized with lower carbon–nitrogen mole ratio and lower hydrogen–nitrogen mole ratio, which could be mainly attributed to the increased protein content. The response of plant nitrogen, grain protein and amylose concentration to the supplemental nitrogen level varied with the cultivars. The results in this study suggested that solution culture technology could improve the production potential of rice. Copyright © 2005 Society of Chemical Industry     

Effects of processing on the distribution of pirimiphos-methyl residues in milling fractions of durum wheat

Three hundred kilograms of durum wheat of two cultivars ‘primadur’ (small kernel) and ‘ardente’ (large kernel) treated with pirimiphos-methyl (PMM) at 10 mg kg⁻¹ were processed into fractions under standard conditions of milling to evaluate the fate and distribution of the residues in the milling fractions. Half the quantity of each variety was processed 7 d after the treatment, and the second half was stored for 127 d in controlled conditions before milling. The residue content in treated grain just before milling as well as in the final 18 milling fractions was determined by GC–MS analysis carried out on crude methanol extracts. During the 127-d storage period, nearly 65% of the PMM initial content was degraded. With the first sub-sample (7 d after treatment), the amount of residue in the processed fractions compared to the total amount in grain prior to milling was reduced by 12.3% and 26.5% for primadur and ardente varieties, respectively. With the 2nd sub-sample (127 d after treatment), the residue losses induced by the milling operations were 21.8% and 24.6%, respectively. Between 79.5% and 74.5%, respectively, of the total amount of recovered residues after milling was concentrated in the bran layers 7 d after treatment and 79.5% and 80.2% after 127 d. The translocation of the residues during milling from the bran-coat to the inner endosperm was significant in all cases: a fraction from 14% to 20% of the total residue content was drawn into the semolina. An interaction between the milling operations and the residue translocation was observed. The greater translocation observed with the ardente cultivar was related to the specific characteristics of the bran-coat structure of this durum variety. With the grain batch held for the longer term, a lower rate of translocation was observed as the level of PMM fell to about a third of that at 7 d. A scenario of the behaviour of the residues during milling in relation to processing and grain conditions was proposed for the assessment of the maximum amount of PMM residues in the premium semolina fractions. The impact for consumer's health of this residual contamination of semolina used for food purposes is discussed.     

碾磨程度对大米特征组分和米粉品质特性的影响

通过测定不同碾磨程度下大米粉的组成含量、X射线衍射、糊化、流变和凝胶质构和结构特性,发现随着碾磨程度增加,大米粉的蛋白质含量从(11.24±0.06)%降到(7.89±0.27)%,直链淀粉含量从(8.51±0.27)%增加到(25.93±2.42)%,米粉中淀粉的XRD吸收峰增强。糊化峰值黏度从(2 025.0±169.2)cp增加到(4 847.0±140.5)cp,糊化温度从(71.82±0.67)℃下降到(70.10±0.04)℃,米粉糊的黏度和弹性增加而流动性降低,凝胶微观结构区域均匀紧密。说明碾磨能够降低大米粉的蛋白质含量,增加直链淀粉含量且对大米粉的糊化和短期老化有促进作用,促进作用均随碾磨程度增加而加强。     

Effect of industrial processing on the distribution of fumonisin B1 in dry milling corn fractions

The aim of this study was to investigate the distribution of fumonisin B1 in various corn milling fractions processed by an industrial plant. Corn kernels and six derived milling fractions (germ, bran, large and small grits, animal feed flour, and flour) were sampled. In addition, in order to evaluate the effect of cooking, samples of polenta were prepared starting from naturally contaminated flour obtained from the industrial processing cycle. The industrial plant worked continuously at a rate of 60 tons per day. Two sublots of 5 tons each were investigated with samples of derived products taken at regular time intervals. Due to a similar heterogeneous distribution of fumonisin B1 with other mycotoxins, such as aflatoxins, the sampling scheme was derived from the European Directive 98/53 for aflatoxins. Both lots of kernels showed fumonisin contamination at 4.54 and 5.09 mg/kg, respectively. Germ, bran, and animal feed flour showed contamination levels, namely 8.92 mg/kg (lot 1) and 9.56 mg/kg (lot 2), 7.08 mg/kg (lot 1) and 8.08 mg/kg (lot 2), and 9.36 mg/kg (lot 1) and 6.86 mg/kg (lot 2) higher than large and small grits and flour (0.39 mg/kg [lot 1] and 0.42 mg/kg [lot 2], 0.60 mg/kg [lot 1] and 1.01 mg/kg [lot 2], and 0.40 mg/kg [lot 1] and 0.45 mg/kg [lot 2], respectively). These results seem to account both for the industrial yields of the derived products and the distribution of fumonisin contamination in a kernel. The cooking of polenta in a domestic pressure cooker did not affect fumonisin contamination because the mycotoxin concentrations were similar to those of the starting flour (0.40 and 0.45 mg/kg).