Occurrence of ochratoxin A in Danish wheat and rye, 1992-99

Ochratoxin A concentrations in rye and wheat in Denmark for 1992-99 are reported. The results show that the concentration of ochratoxin A is higher in rye than in wheat for both conventionally and organically grown rye and wheat. The levels in organically grown rye are higher than in conventionally grown based on multiyear mean contents. However, the difference between the two groups of cereals has decreased since the Danish food-monitoring system for ochratoxin A was started in 1986; 2.0% of all samples exceeded the Danish maximum limit of 5 µg kg -1 introduced in 1995. For rye samples, 3.2% exceeded the maximum limit, and for wheat samples, 0.5% exceeded the maximum limit.     

Phenolic acid profiles and antioxidant activities of wheat bran extracts and the effect of hydrolysis conditions

Four different types of wheat bran were extracted and analyzed for phenolic acids using the Folin–Ciocalteu method and HPLC. The extracts and their hydrolysis products were also evaluated for their antioxidant activities. The total phenolic content of the red wheat bran was higher than that of the white wheat. We found that the majority of the phenolic acids existed in a bound form in wheat bran. These phenolic acids can be released by hydrolyzing the bran under alkaline or acidic conditions; however, the former was more efficient in the release of free phenolic acids than the latter. Ferulic, vanillic, and syringic acids were the major individual phenolic acids in the studied wheat bran. The main portion of the total ferulic acid was from alkaline hydrolysis. The alkaline hydrolysable fractions had greater antioxidant activities, while the acid hydrolysable fractions showed lower activities in both the red and white bran. The antioxidant activity of bran extract was stronger than that of free phenolic acids.     

Use of Aspergillus flavus to evaluate the relative nutritive value in cultivars of rye, wheat and triticale.

Aspergillus flavus Link ex Fr., was used to evaluate the relative nutritive value in a set of breeder's material involving 2 rye, 5 wheat and 33 triticale samples ranging in protein content from 12.6 to 21.9%. The samples were tested at equal nitrogen level. Total dry weight of the mycelium produced after 72 h of shaking was used as the index of biomass. The biomass showed a negative correlation with protein content and dye-binding capacity, and a positive correlation with protein index and lysine in protein. The fungus was able to pick up an “unusual” sample which had high protein and high lysine content. In addition, the effects of initial inoculum concentration, pH value and excess soluble starch on biomass production were studied. Initial spore concentrations of 10⁶ and 10⁸/ml and pH values of 3.5 and 6.2 did not make significant changes in biomass. However, the presence of excess soluble starch increased the mycelial yield without basically altering the results. Lysine dependent strains of Neurospora crassa and Aspergillus nidulans did not grow well in shake cultures and it appeared that the carbohydrate energy source was left unutilised. This “left over” starch was considered to be a possible source of error in biomass determination.     

Real-time PCR systems for the detection of the gluten-containing cereals wheat,spelt, kamut,rye, barley and oat

Real-time PCR assays, using TaqMan^® probes, were applied to detect the gluten-containing cereals. Homologues target sequences encoding high molecular weight (HMW) glutenin were chosen to detect wheat, kamut, spelt and rye. For detecting barley, the gene Hor3 was selected. For the detection of oat the gene encoding the 12S seed storage protein was chosen. Based on this sequence data, primer and probe sequences were generated for the real-time PCR. A plant specific primer probe system based on 18S rRNA gene was chosen to detect amplificability of the extracted nucleic acids. The specificity of the primer and probe systems was checked using different lines from different origins of the species to be detected. The HMW glutenin system is specific for the corresponding species, as are the systems for the barley Hor3 gene and the oat 12S seed storage protein. The sensitivity of the systems was determined testing different matrices. With the HMW glutenin system 2.5 mg/kg of wheat in vegetable food matrices and 5 mg/kg of wheat in meat products were detected. The oat and the barley specific systems resulted in a sensitivity of 10 mg/kg. The detection method showed a satisfactory ruggedness.     

Phenolic compounds and fatty acids in different parts of Vitis labrusca and V. vinifera grapes

trans-Resveratrol, antioxidant activity, phenolic compounds, proximate composition, and fatty-acid composition were quantified in different parts (peel, pulp, and seeds) of four grape varieties: Brazil (Vitis vinifera), Benitaka (V. vinifera), Isabel (Vitis labrusca) and Niagara (V. labrusca). Large concentrations of polyunsaturated fatty acid (18.84 and 9204.27 mg 100 g^− 1), linoleic acid (LA, 18:2n-6), from 5890.87 to 9148.93 mg 100 g^− 1, and alpha-linolenic (LNA, 18:3n-3), from 5.25 to 56.85 mg 100 g^− 1, were found in different parts of the four grape varieties. The lowest concentrations necessary for 50% inhibition of DPPH were (9.26 to 126.91 ??g mL^− 1) in seeds; the pulp did not have antioxidant activity. The total phenolic content varied between 0.04 and 122.35 mg EAG g^− 1; seeds had the highest concentrations (89.83 to 122.35 mg EAG g^− 1), especially in Niagara and Isabel varieties. trans-Resveratrol was detected in peels (1.17 to 12.96 ??g g^− 1) and seeds (2.03 to 2.44 ??g g^− 1) of the four varieties; however, it was absent in the pulp.     

Phenolic acids in cereal grain: Occurrence,biosynthesis, metabolism and role in living organisms

Studies on plant metabolism, including those on cereals, increasingly focus on plant phenolic compounds, e.g. phenolic acids and flavonoids. The aim of this study was to present a comprehensive picture of major phenolic acids in grain, starting from their biosynthesis, their occurrence and finally their role in the vegetation of cereals. It is clearly connected with the polygenic plant resistance to pathogens, particularly toxin-forming fungi. Other crucial aspects include the transformations that take place during the technological processing of grain, their metabolic pathway in the human organism as well as the presentation of the health-promoting effect of grain processing products containing phenolic acids. These compounds are used as precursors of bioactive compounds commonly applied both for therapeutic purposes and in the cosmetics, engineering and food industries. An advantage of phenolic acids is the fact that they may be metabolized by microorganisms found in nature and thus they provide an alternative to the increasing load of man-made chemicals in the environment.     

Use of wheat,triticale and rye flours in layer cake production

In this study, the capacity of obtaining high quality layer cakes from rye and triticale lines was analysed and compared to wheat lines. The samples were characterised considering grain hardness, flour composition and quality parameters as protein, pentosan, damaged starch, pasting viscosity and functional predictive test – solvent retention capacity test. Cakes were analysed in weight, symmetry, volume, volume index (VI) by measuring the height in different points of the cake, crust and crumb colour, crumb structure and texture. Wheat and triticale cakes showed similar characteristics. Rye cakes showed higher volume and lower weight than those with crumbs darker in colour, higher adhesiveness, springiness and resilience. The multiple regression analysis was used to develop an equation for cake volume index prediction. The best‐fit linear regression model was: VI = 14.75 – 0.14 × protein + 0.93 × water soluble pentosan – 0.27 × total pentosan. Despite the differences, high quality cakes can be elaborated with rye, triticale and soft wheat cultivars.     

Detection of wheat adulteration of spelt flour and products by PCR

 To date, no general method to detect wheat [Triticum aestivum vulgare (Vill.) Mackey] adulteration of spelt [T. aestivum spelta (L.) Thell.] exists. Exploiting a published allelic difference in γ-gliadin gene GAG56D, we developed and evaluated three PCR-based methods to determine the proportion of wheat in spelt flour and products. A sensitive wheat-specific PCR system was designed. Moreover, a heterologous internal standard was constructed for quantitative competitive (QC-)PCR. The standard was arbitrarily calibrated to 5% wheat DNA in spelt DNA. A PCR-RFLP system consisting of a GAG56D-specific PCR system with subsequent restriction was used to estimate the relative proportions of wheat and spelt in DNA mixtures. The three methods were successfully applied to seven commercial spelt samples and one self-produced bread. Five and three of the seven samples were found to contain more than 5% and 10% wheat, respectively. One sample appeared to contain no spelt at all. Analyzing the bread crumb with PCR-RFLP, we were able to estimate the wheat content of the flour which was used to produce the bread and thus demonstrated the applicability of PCR-RFLP to quantify processed products. Received: 24 March 2000     

Effect of blending of raw and steamed wheat flour on the rheological characteristics of dough

 The blended dough made from raw wheat flour and wheat flour steamed for 15 min at a ratio of 1 : 1, along with minor ingredients (salt, oil) showed reduced farinograph water absorption capacity. The stability of the blended dough with oil was reduced while the mixing tolerance index increased. The inclusion of salt in the blend increased the resistance to extension and also the area under the curve. The hardness and cohesiveness measured by means of texture profile analysis decreased with the inclusion of oil in the blend, while increasing with the addition of salt. The Rapid Visco Analyser used to measure pasting characteristics showed a peak viscosity which increased for the blend with salt, but decreased for that with oil. Similarly, the hot paste viscosity, cold paste viscosity and area under the curve increased for the blend with salt, but decreased for the blend with oil. Received: 5 February 1999 / Revised version: 21 April 1999     

Content of trans fatty acids in margarines, plant oils, fried products and chocolate spreads in Austria

 On the Austrian market a selection of the available margarines, refined and cold pressed plant oils, chocolate spreads, snacks and fast food products were collected and the content of trans-fatty acids (TFA) was determined by a GLC procedure. The highest levels of TFA were observed in fast food products (mean, 5.9%, maximum, 21% of fatty acids), chocolate spreads (mean, 4.9%, maximum, 8.9% of fatty acids) and snacks (mean, 2.9%, maximum, 16% of fatty acids). Margarines with a "<1% TFA" declaration contained low amounts (0.3–0.8%), while the content of margarines with no such declaration was much higher (3.0–3.7%). A 7 h oxidation of plant oils at 120  °C demonstrated that the higher levels of TFA in heated oils are not associated with oxidation processes at this temperature. Based on the analysed data, the mean TFA intake (currently <4 g/day) has decreased due to a change in manufacturing conditions and the choice of unhydrogenated plant oils. In spite of this a diet high in snacks, fast food products or chocolate spreads, all products which are popular amongs children and adolescents, may increase the TFA intake up to >10 g/day. Received: 23 April 1999 / Revised version: 11 June 1999     

Organic acids produced by lactobacilli, enterococci and yeasts isolated from Picante cheese

 Four species of bacteria (Enterococcus faecium and Enterococcus faecalis, Lactobacillus plantarum and Lactobacillus paracasei) and three species of yeasts (Debaryomyces hansenii, Yarrowia lipolytica and Cryptococcus laurentii), previously isolated from Picante cheese, were cultured in ovine and in caprine milk and assayed for sugar and organic acids metabolism for 6 days. The results indicated that both milk types can be coagulated by the four strains of lactic acid bacteria. Lb. paracasei led to a faster and greater reduction in pH. Production of lactic acid correlated to lactose degradation, and was highest for Lb. paracasei followed by E. faecium; citrate metabolism was apparent for E. faecalis and, to a lesser extent, for E. faecium, Lb. plantarum and Lb. paracasei. Relatively high contents of formic acid were found when inoculation was with Enterococcus and with Lb. plantarum. Received: 4 February 1999     

Identification of durum wheat cultivars and monovarietal semolinas by analysis of DNA microsatellites

 Microsatellites isolated in bread wheat were used to identify 20 Italian durum wheat (Triticum turgidum var. durum L.) cultivars. A total of 15 microsatellite primer pairs were tested against DNA extracted from leaf tissue, single seeds and semolina. Twelve markers showed allelic polymorphism among the 20 cultivars, providing a total of 41 different alleles. Firstly, an analysis of microsatellite informativeness in the chosen set of durum wheat cultivars was made and a set of highly polymorphic microsatellites was established. Secondly, among the most polymorphic cultivars, the minimum number of microsatellites able to distinguish all cultivars was determined. A set of five microsatellites was found sufficient to differentiate the durum wheat cultivars examined. The method is directly applicable to seeds and semolina, and is suitable for detecting seed mixtures in the same seed lot. Received: 22 February 1999 / Revised version: 19 April 1999     

Aflatoxin production in three selected samples of triticale,wheat and rye grown in Argentina

Little is known about mycotoxin contamination of triticale, a hybrid resulting from crossing wheat and rye. The purpose of the present work was to evaluate triticale as a substrate for aflatoxin accumulation in comparison with its parents. Aflatoxin (B₁, B₂, G₁ and G₂) accumulation curves were obtained for the three substrates inoculated with Aspergillus parasiticus NRRL 2999 and incubated at 25 °C and water activity 0.925 for 10 weeks. Wheat and triticale were poor substrates for aflatoxin production. Rye was more prone than the other substrates to fast colonisation by A parasiticus and accumulated larger aflatoxin quantities over the whole incubation period. The maximum aflatoxin concentration in rye (11 840 µg kg⁻¹) was significantly larger (p < 0.05) than those obtained in wheat (2150 µg kg⁻¹) and triticale (2850 µg kg⁻¹). © 2000 Society of Chemical Industry     

Incorporation of dairy ingredients into wheat bread: effects on dough rheology and bread quality

 Dairy ingredients are used in breadmaking for their nutritional benefits and functional properties. The effects of the traditionally-used whole and skimmed milk powder, sodium caseinate, casein hydrolysate and three whey protein concentrates on dough rheology and bread quality were studied. Whole and skimmed milk powders improved sensory characteristics. Sodium caseinate and hydrolysed casein displayed beneficial functional properties in breadmaking including low proof time, high volume and low firmness. Both ingredients increased dough height measured with the rheofermentometer. Bread with 2% or 4% sodium caseinate added was rated highly in sensory evaluation. Incorporation of whey protein concentrates generally increased proof time, decreased loaf volume and decreased dough height measured with the rheofermentometer. Received: 6 April 1999 / Revised version: 13 July 1999     

Determination of fatty acid composition and total trans fatty acids of Turkish biscuits by capillary gas-liquid chromatography

 In this research, fatty acid composition and total trans fatty acid contents of six types of biscuit produced by four different Turkish companies were determined by capillary gas-liquid chromatography. Total fat contents of the biscuit samples ranged between 8.5% and 26.0%. The highest fat content was determined in sesame biscuits (average 24.4%) and the lowest in petit beurre biscuits (average 13.5%). Total fat contents varied even for the same type of biscuit as a result of the use of different recipes by each company. The major fatty acids in the samples were C_16 : 0, C_18 : 0, trans C_18 : 1, C_18 : 1, trans C_18 : 2 and C_18 : 2. Depending on the biscuit type, total unsaturated fatty acid contents were between 52.1% and 72.8%. The ranges of total trans fatty acid contents in biscuit types were petit beurre 1.9–29.0%, sesame 15.0–23.1%, baby 3.0–30.5%, oat 17.6–22.4%, cocoa 1.5–22.9% and finger 1.0–24.7%. It is clear from the results that the percentage of trans fatty acids in the total fat content is significant because of the use of hydrogenated vegetable oils in biscuit production. Received: 26 July 1999 / Revised version: 9 September 1999     

Fatty acids of a salami-type sausage made of Baltic herring fillets, pork and lard

 The fatty acid composition of "fish wurst", a fermented salami-type sausage made of pork, lard and Baltic herring fillets (Clupea harengus var. membras) was investigated. Changes in the proportions of the 35 most abundant fatty acids were examined throughout the 1-month ripening period followed by a 4-month storage period. The fat composition of the product was stable (32–35%) and retained the characteristics of the main ingredients: oleic acid (37.4%, mean of three production batches) palmitic acid (23.7%) and linoleic acid (10.7%) from lard and fish, stearic acid (11.7%) mainly from lard, and palmitoleic acid (3.0%) and long-chain (C20–C24), polyunsaturated fatty acids (c.a. 6%) mainly from fish. During the 4-week ripening period a statistically significant increase (P≤0.05) was detected in the proportions of minor fatty acids only, i.e. eicosenoic acid (20 : 1n-9), eicosadienoic acid (20 : 2n-6), docosadienoic acid (22 : 2n-6) and docosatrienoic acid (22 : 3n-3). During the 4-month storage of the ripe sausage, the fatty acid composition stabilized. Only the proportion of stearic acid increased significantly during storage, from 11.7% to 12.5%. Received: 23 January 1998 / Revised version: 1 April 1998     

Fatty acids of a salami-type sausage made of Baltic herring fillets, pork and lard

 The fatty acid composition of "fish wurst", a fermented salami-type sausage made of pork, lard and Baltic herring fillets (Clupea harengus var. membras) was investigated. Changes in the proportions of the 35 most abundant fatty acids were examined throughout the 1-month ripening period followed by a 4-month storage period. The fat composition of the product was stable (32–35%) and retained the characteristics of the main ingredients: oleic acid (37.4%, mean of three production batches) palmitic acid (23.7%) and linoleic acid (10.7%) from lard and fish, stearic acid (11.7%) mainly from lard, and palmitoleic acid (3.0%) and long-chain (C20–C24), polyunsaturated fatty acids (c.a. 6%) mainly from fish. During the 4-week ripening period a statistically significant increase (P≤0.05) was detected in the proportions of minor fatty acids only, i.e. eicosenoic acid (20 : 1n-9), eicosadienoic acid (20 : 2n-6), docosadienoic acid (22 : 2n-6) and docosatrienoic acid (22 : 3n-3). During the 4-month storage of the ripe sausage, the fatty acid composition stabilized. Only the proportion of stearic acid increased significantly during storage, from 11.7% to 12.5%. Received: 23 January 1998 / Revised version: 1 April 1998     

Lipids classes, fatty acids and carotenes of the leaves of six edible wild plants

 α-Linolenic acid and unusual fatty acids of the ω3 and ω6 series play an important role in the modulation of human metabolism. The presence of these acids in the leaves of several edible wild plants has recently been reported. In this study, six edible wild species were selected in order to establish the fatty acid compositions in their leaf lipids. Thus, young leaves from Amaranthus viridis L.(blet), Chenopodium album L. (goosefoot), Crithmum maritimum L. (rock samphire), Plantago major L. (plantain), Portulaca oleracea L. (purslane) and Verbena officinalis L. (vervain) yielded 1.50, 2.20, 3.02, 1.46, 3.81, and 2.28 g of lipids per 100 g dry plant material. Silica gel chromatography yielded 0.64 g (Plantago major) to 2.19 g (Crithmum maritimum) neutral lipids, 0.37 g (Plantago major) to 1.60 g (Portulaca oleracea) glycolipids, and 0.26 g (Crithmum maritimum) to 0.57 g (Verbena officinalis) phospholipids per 100 g (dry weight). Gas chromatography (GC) showed the major fatty acids to be 18 : 3ω3, 18 : 2ω6 and 16 : 0 in all fractions, with high concentrations of 18 : 3ω3 in the glycolipid fraction. GC-mass spectrometric analyses did not reveal the presence of unusual fatty acids. Carotenes were found in high concentrations, ranging from 30.5 mg/100 g (Chenopodium album) to 89.2 mg/100 g (Portulaca oleracea). The analyzed plants are rich sources of essential fatty acids (18 : 2ω6 and 18 : 3ω3) and also of carotenes. Received: 29 October 1998     

Importance of amounts and proportions of high molecular weight subunits of glutenin for wheat quality

 High molecular weight (HMW) subunits of wheat glutenin are generally considered to play a key role in gluten formation and structure, and to be closely related to wheat quality. Though quantities of HMW subunits in flour have been proposed to be as important for wheat quality as their structures, only few quantitative data are available in the literature. Therefore, two assortments of wheat consisting of 13 international and 16 German cultivars were analyzed for their contents and proportions of single HMW subunits using an extraction and HPLC procedure on a micro-scale. The results were compared with quantitative data from the literature that were obtained by sodium dodecylsulfate polyacrylamide gel electrophoresis combined with densitometry or by reversed-phase HPLC combined with UV detection. The quantitative analyses demonstrated that the contents of HMW subunits varied within a broad range dependent on genotype and growing conditions. The proportions of subunits within a given subunit combination, however, varied only within a small range. Generally, subunits 2, 5, 7, 10 and 12 were major components and subunits 1, 2*, 6, 8 and 9 were minor components. The levels of HMW subunits were highly correlated to dough development time, maximum resistance of dough and gluten, and bread volume. Among HMW subunits the x-type components (subunits 1–7) were much more important than the y-type components (subunits 8–12). In particular, the presence of subunit 5 (which has an additional cysteine residue) and of subunit 7 (which occurs in the greatest amounts) contributed to high wheat quality. Received: 22 June 1999     

Investigations on the extractability of gluten proteins from wheat bread in comparison with flour

 Immunochemical methods are recommended for the quantitation of small amounts of gluten in food produced for those with coeliac disease. A major problem, however, is the reduced extractability of gliadin, the toxic factor of gluten, with aqueous alcohol, when foods have been heat-processed. A combined extraction/HPLC procedure was used to study the extractability of all gluten protein types from wheat flour and bread under both non-reducing and reducing conditions. Gliadin isolated from wheat flour was used as a reference protein for quantitation. The results indicate that the extractability of gliadin from bread with 60% ethanol under non-reducing conditions is strongly reduced. α- and γ-gliadins are much more affected than ω-gliadins, and less gliadin was extracted from the crust than from the crumb. For a complete extraction of gliadins from bread, reducing conditions and increased temperature are required. However, glutenin subunits are coextracted with the gliadins. This extract can be used for the quantitation of total gluten proteins by RP-HPLC. The recovery of gliadin added to flour before dough-mixing and bread-making is 98%. Received: 16 February 1998