Showing papers on "Avena published in 1996"

Sensory and chemical studies of lipid oxidation in raw and heat-treated oat flours

Abstract: Cereal Chem. 73(5):579-587 The storage stability of oat flours (Avena sativa L.) was investigated by sensory and chemical methods. Raw and heat-treated flour samples of three cultivars of oats (Kapp, Mustang, and Svea) were stored at 23°C and 50% relative humidity for 0, 5, 18, and 42 weeks before analyses. Descriptive sensory analysis and analyses of total fatty acids (FA), free fatty acids (FFA) and volatile lipid oxidation products were performed after each storage period. Storage of raw flours for five weeks resulted in 66% FFA but stable levels of flavors and volatile compounds. After 18 weeks, the level of volatiles and FFA was higher, while the samples at 42 weeks had an intense paint flavor, high levels of several volatiles, and reduced levels of FA and FFA. The major volatiles in stored oat flours were hexanal and 2-pentyl-furan. The other carbonyls were mainly aldeCompared to wheat, the lipid content of oats is =5 times higher (Percheron and L6liger 1990) and the lipolytic enzymes are 10-15 times more active (Matlashewski et al 1982). Milling to flours allows lipids and enzymes to react and release free fatty acids (FFA), which are much more susceptible to lipid oxidation than the original lipids. Oats contain a variety of antioxidants, including tocopherols and phenolic acids (Kalbasi-Ashtari and Hammond 1977), and are thus considered to be fairly stable towards nonenzymatic oxidation (Percheron and Loliger 1990). However, high levels of unsaturated FFA and the presence of lipoxygenase favor lipid oxidation. High moisture levels may further enhance the enzymic oxidation, and exposure to heat, oxygen, catalysts, or light accelerates nonenzymic oxidation (Galliard 1994). While most oats for feed are enzyme-active, most commercially processed oats for human consumption are stabilized by heat-treatment. An adequate heat process inactivates lipolytic enzymes and develops the characteristic, pleasant flavor that is associated with highquality commercial oat products. Optimum stability is expected after a heat treatment strong enough to inactivate lipolytic enzymes but mild enough to protect the natural antioxidants in oats and prevent excessive oxygen exposure due to drying (Galliard 1994). The storage stability of cereals may be studied by sensory or chemical methods. Studies of milled, rolled and whole cereals by use of descriptive sensory analysis and chemical methods have been reported in rice (Paule and Powers 1989, Piggott et al 1991), pearl millet (Lai and Varriano-Marston 1980), and oats (Dahl et al 1989; Molteberg et al, in press). Oat oil stability has also been studied (Fors and Schlich 1989). Most of the studies investigated the effects of processing and storage conditions and related the sensory attributes related to various lipid oxidation products. In rice, removal of the bran and aleurone layer increased the storage stability and reduced the levels of FFA, hexanal, and carbonyls

C-banding variation in the Moroccan oat species Avena agadiriana (2n=4x=28).

Abstract: The C-banding technique was used to describe the chromosomes of a relatively recently-discovered Moroccan oat species, Avena agadiriana (2n=4x=28). A substantial amount of polymorphism for arm ratios and C-banding patterns was observed among five accessions of this species. However a common set of ten putatively homologous chromosomes was identifiable among the five accessions. The chromosomes of A. Agadiriana do not closely match those of any of the previously described diploid or tetraploid oat species in terms of their arm ratios and C-banding patterns. However, their overall C-banded appearance generally resembles the A/B/D groups of chromosomes of Avena species, rather than the more hetrochromatic C genomes. Implications of these findings in terms of chromosome evolution in the genus Avena are discussed.

Effects of CO2 and nutrient enrichment on tissue quality of two California annuals

Abstract: The effects of CO2 enrichment and soil nutrient status on tissue quality were investigated and related to the potential effect on growth and decomposition. Two California annuals, Avena fatua and Plantago erecta, were grown at ambient and ambient plus 35 Pa atmospheric CO2 in nutrient unamended and amended serpentine soil. Elevated CO2 led to significantly increased Avena shoot nitrogen concentrations in the nutrient amended treatment. It also led to decreased lignin concentrations in Avena roots in both nutrient treatments, and in Plantago shoots and roots with nutrient addition. Concentrations of total nonstructural carbohydrate (TNC) and carbon did not change with elevated CO2 in either species. As a consequence of increased biomass accumulation, increased CO2 led to larger total pools of TNC, lignin, total carbon, and total nitrogen in Avena with nutrient additions. Doubling CO2 had no significant effect on Plantago. Given the limited changes in the compounds related to decomposibility and plant growth, effects of increased atmospheric CO2 mediated through tissue composition on Avena and Plantago are likely to be minor and depend on site fertility. This study suggests that other factors such as litter moisture, whether or not litter is on the ground, and biomass allocation among roots and shoots, are likely to be more important in this California grassland ecosystem. CO2 could influence those directly as well as indirectly.

Development and oviposition of peregrinus maidis (homoptera : delphacidae)on various host plants

Abstract: The development and oviposition of Peregrinus maidis (Ashmead) (Homoptera: Delphacidae), a serious pest and the only known vector of maize stripe tenuivirus and maize mosaic rhabdovirus in tropical and subtropical areas, was studied on the following plants in the laboratory: corn (Zea mays L. var. Saccharata ‘Guardian’), itch grass (Rottboellia exaltata L.), rice (Oryza sativa L. var. Mars, Saturn, Nato, Bellevue, Labelle, Labonnet, and Starbonnet), sorghum (Sorghum bicolor (L.) Moench var. AKS 614), goose grass (Eleusine indica (L.) Gaertn), oats (Avena sativa L.), rye (Secale cereale L.), gama grass (Tripsacum dactyloides L.), barnyard grass (Echinochloa crusgalli L.) and sugarcane (Saccharum officinarum L.). Peregrinus maidis nymphs did not develop on rye, oats, rice and sugarcane, but the adults survived for various lengths of time on these test plants. The average length of nymphal development on corn, itch grass, sorghum, goose grass, barnyard grass and gama grass was 17.20, 17.87, 20.21, 24.97, 27.24 and 60.50 days, respectively. Adult longevity (X SD) on corn, gama grass, itch grass, sorghum, goose grass, and barnyard grass was 36.1 20.0, 42.7 16.6, 28.3 11.9, 7.6 6.4, 8.1 7.3 and 7.3 6.6 days, respectively. Oviposition rarely occurred on sorghum, goose grass and barnyard grass. The numbers of eggs laid per day per female on corn, itch grass and gama grass was (X SD) 21.0 2.0, 6.4 6.6, 3.5 3.0 eggs, respectively; the numbers of eggs per female per life on these respective plants was (X SD) 612 170.1, 146 156.7 and 48 45.6 eggs.

Changes in free, esterified and glycosidic phenolic acids in cereal grains during the after-ripening

Abstract: Experiments were conducted on rye (Secale cereale L., cv, Dankowskie Zlote) triticale (Triticosecale, cv. Dagro), barley (Hordeum vulgare L., cv. Ars) and oat (Avena sativa L., cv. Boruta) caryopses. Caryopses from each species were collected in full ripeness and divided into two batches. From one batch phenolic acids were isolated and fractionated immediately after harvesting, and from the other part the same was done after six months storage in dry state. Dormant caryopses slowly lost their dormancy by the process of after-ripening, and after six months storage in dry state (in all investigated species) caryopses were completely released from dormancy. During after-ripening quantity and quality changes were found both among free and soluble bound phenolic acids. In all examined species, the decreased level of free and conjugated forms (esters and glycosides) was found during several months storage in dry state. This indicates a positive correlation between dormancy levels and the contents of phenolic acids in the process of after-ripening, supporting the idea of involvement of phenolic compounds in the control of dormancy and sprouting in cereal caryopses.

Relationships among some quantitative traits and heritablities in cultivated oats (Avena sativa L.)

Abstract: The objectives of this study were to examine the relationships among quantitative traits and to estimate their broad sense heritabilities in cultivated oats (Avena sativa L.). Four oat crosses were used in this experiment. Biological yield had the highest correlation with grain yield in all F2 populations, followed by harvest index. Grains per panicle appeared to be the most useful trait to use in indirect selection for grain yield among yield components in terms of heritability values and correlations with grain yield. Grain yield per plant significantly and positively associated with groat oil content in two oat populations. The broad sense heritability values of groat oil content ranged from 13 to 77%. Grain yield per piânt had heritability estimates between tow and moderate values.•