Low Tannin Content Research Articles

Evaluating effects of nursery and post-planting nutrient regimes on leaf chemistry and browsing of eucalypt seedlings in plantations

We examined the effects of nursery and field nutrient treatments on leaf chemistry and browsing during establishment of Eucalyptus globulus (two trials; Cressy and Dunalley) and Eucalyptus nitens (one trial; Tyenna) seedlings. Seedlings had high- or low-fertilizer application treatments in the nursery, were fertilized or not in the field and were individually fenced (used for leaf chemistry sampling) or not (used for browsing assessment). The high-fertilizer nursery treatment resulted in relatively high foliar nitrogen (N) and low tannin content (all seedling types), and high total essential oils (seedling batch planted at Cressy only), but nursery fertilizer level did not affect dry matter, neutral detergent (NDF) or acid detergent fibre (ADF) or lignin. After planting, levels of N, tannins and total essential oils changed over time, but the degree differed between sites. Field fertilizing generally had no effect on leaf chemistry during 10 weeks after planting. Across sites, the pattern of browsing was the same. Seedlings with the high-fertilizer nursery treatment were browsed more than the low-fertilizer nursery treatment, though the difference was only significant at two of the three sites. Thus trends in browsing damage were consistent with differences in foliar N and tannins as a result of nursery- and not field fertilizing treatment. Manipulation of seedling chemistry, using particular fertilizer application regimes in the nursery, may be one tool for managers wishing to decrease seedling damage by browsers, particularly when browsing severity is not extreme.

Chemical and sensory characterization of DOC red wines from Marche (Italy) related to vintage and grape cultivars.

Monomeric phenols, color and copigmentation parameters, pigments with different chemical structure, tannin, glucose, fructose, glycerol, ethanol, and organic acids were determined in DOC red wines from Marche (Italy), obtained during three different vintages ranging from 1996 to 2000. The intensity of the bitter and astringent tastes of the wines was determined with panel tastings. Lacrima di Morro and Vernaccia di Serrapetrona (obtained from local cultivars) were different from Rosso Piceno, Rosso Piceno Superiore, and Rosso Conero (produced from different percentages of Sangiovese and Montepulciano). Vernaccia, a red, sweet, "spumante" wine, was an outlier. Lacrima showed a low tannin content, a high content of small pigments and phenols, and a high ratio of copigmented color, which persisted after 3 years of aging. The chemical determinations accounted for a high percentage of variability of measured panel astringency, copigmented color, and measured wine absorbance at 520 nm. It was not possible to create a predictive model for bitterness.

Effect of polyethylene-glycol on the chemical composition and nutrient availability of olive ( Olea europaea var. europaea) by-products

Total extractable polyphenols (TEP), total extractable tannins (TET), total extractable condensed tannins (TECT) and total condensed tannins (TCT) were quantified in two very important olive by-products: the two-stage dried olive cake (TSDOC) and the olive leaves (OL). The effect of polyethylene-glycol (PEG) addition (0, 20, 60, 100 and 200 g/100 g by-product) on the chemical composition, in vitro digestibility and in situ degradability was studied. The effect of PEG addition (0, 2 and 20 g/100 g by-product) to TSDOC and OL on the in situ–in vitro intestinal availability of both rumen undegraded and dietary protein was also studied using different approaches: (i) apparent intestinal digestibility of ruminal undegraded protein (AIDUP) or amino acids (AIDUAA); (ii) apparent intestinal digestibility of dietary protein (AIDDP); (iii) ruminally degradable and intestinally digestible dietary protein (100−ADF-N). Results obtained in Granadina goats and Segureña sheep were compared. The nitrogen fraction attached to acid detergent fibre (ADF-N) decreased significantly ( P<0.01 and <0.001 for TSDOC and OL, respectively) by PEG addition. A significant effect was observed in TEP ( P<0.05 and <0.01 for TSDOC and OL, respectively), TET ( P<0.001 for both TSDOC and OL) and TECT ( P<0.001 for both TSDOC and OL). A significant decrease in cell wall components was only observed in OL treated with PEG. The in vitro digestibility, which was significantly higher when rumen liquor from goats was used in comparison with sheep, especially for TSDOC, significantly increased by the PEG addition. This effect was observed in both, TSDOC (from 0.202 to 0.328 IVOMD) and in OL (from 0.349 to 0.446 IVOMD). The effect of the animal species on the characteristics of the ruminal degradation of TSDOC and OL was variable and concerning effective degradability (ED) it was significantly higher in goats than in sheep (0.490 and 0.424, respectively) for OL protein. The effect of PEG addition was more pronounced in TSDOC than in OL. All the parameters of the TSDOC rumen degradation profiles increased significantly with increasing amounts of PEG (from 0.435 to 0.765 for ED of TSDOC protein). On the contrary, only the ED of OL dry matter increased ( P<0.01) by the addition of 2 g of PEG (from 0.535 to 0.582). The availability of ruminal undegraded and dietary protein in the small intestine, estimated in situ–in vitro with different approaches, significantly increased by the addition of two grams PEG/100 g by-product, while a further increase in the amount of PEG resulted in a decrease of intestinal availability. Although low tannin content in TSDOC and OL, addition of 2 g of PEG/100 g of by-product improved nutrient availability either at the rumen and intestine level. The effect was more important for sheep than goats.

Winter browsing on Alaska feltleaf willow twigs improves leaf nutritional value for snowshoe hares in summer

In boreal forests, browsing by mammals on winter‐dormant twigs increases leaf nitrogen, leaf greenness, and leaf size. This suggests browsing reduces competition among meristems for mineral nutrients, and in particular, competition for nitrogen. Winter browsing also reduces the shoot carbohydrate reserves used by leaves to produce condensed tannin. These effects of winter browsing are predicted to improve the nutritional value of leaves for mammals because they increase the mass of digestible nitrogen in leaves. This hypothesis was tested using Alaska feltleaf willow and the snowshoe hare as the experimental system. Six in vivo indicators of leaf nutritional quality were used to compare leaves from winter‐browsed plants with leaves from unbrowsed plants. The indicators used were dry matter intake, nitrogen intake, condensed tannin intake, dry matter digestibility, apparent digestibility of nitrogen and nitrogen retention. The results obtained were in agreement with the above hypothesis. In early summer, at the time snowshoe hares and other northern herbivores reproduce, hares fed leaves from browsed plants consumed more nitrogen, digested more of the nitrogen they consumed, and retained more of the nitrogen they digested than did hares fed leaves from unbrowsed plants. The high nitrogen content and low tannin content of leaves from browsed plants may explain this browsing caused increase in leaf nutritional value. How these positive effects of winter browsing on snowshoe hare nutrition at the time of reproduction might affect hare population dynamics are briefly discussed.

Polyphenols from Honeybush tea (Cyclopia intermedia).

The fermented leaves and stems of Cyclopia intermedia are used to brew Honeybush tea, a herbal tea indigenous to South Africa. The plant is also used to manufacture a sweet herbal infusion used for restorative properties such as soothing coughs and alleviating bronchial complaints including tuberculosis, pneumonia, and catarrh. It is claimed to have a low tannin content and no caffeine and contains various antioxidants. Continued investigations into the phenolic content of the leaves and stems of C. intermedia yielded tyrosol and a methoxy analogue, 2-[4-[O-alpha-apiofuranosyl-(1' '-->6')-beta-d-glucopyranosyloxy]phenyl]ethanol, 4-[O-alpha-apiofuranosyl-(1' '-->2')-beta-d-glucopyranosyloxy]benzaldehyde, five glycosylated flavonols, two isoflavones, four flavanones, two isoflavones, and two flavones. Structure elucidation was done by NMR, CD, and MS methods. Because flavonoids are presumed to contribute significantly toward the scavenging effects of active oxygen species, our results indicate that the tentative claimed health-promoting properties may be attributed to the presence of these and other phenolics in C. intermedia.

A seven-parental diallel analysis of nutritional composition of common beans

Genetic information on combining ability and the type of gene action that governs the inheritance of economically important quantitative characters can be an immense help to the breeder. Such information can assists the plant breeders in selection of suitable parents and the appropriate breeding procedure. Therefore, a 7 × 7 diallel analysis of combining ability of three nutritional components in beans (Phaseolus vulgaris L.) were conducted. The aim of the study was to obtain information on the inheritance of traits and to identify best parents for hybridization. This study showed that estimates of both the combining ability (general and specific), and reciprocal variances were significant for both protein and tannin content, whereas only reciprocal variance was significant for phytate. The protein and tannin ratios of the general to specific combining ability variances were 1.0 and 2.0, respectively. These values indicated that both additive and non-additive genetic variances are important in the inheritance of protein. However, the magnitude of general combining ability of tannin was higher than the specific combining ability variance, indicating the predominant role of additive genetic variance. The performance of the parents for percent protein content was highly associated with their general combining ability effects. The three parents, BBL 254 (P7), PI 300657 (P4), and BBL 290 (P3) were good general combiners for protein and, thus, could be utilized for breeding high protein genotypes. The best combiners for tannins were BBL 254, BBL 290, N80097 (P5), and Eagle (P1). The best specific combinations for protein were PI 300657 × PI 304833 (P4 × P6), Eagle × PI 304833 (P1 × P6), Eagle × N80097 (P1 × P5), Pinto 111 × PI 300657 P2 × P4), and Eagle × BBL 290 (P1 × P3). Lower tannin content was observed in white-seeded genotypes compared to black or pinto beans. Reciprocal crosses were also significant and desirable for protein, tannin, and phytate values. Therefore, it is suggested that caution should be exercised when selecting male and female parents in hybrid production. Recurrent selection and reciprocal recurrent selection could be suitable breeding procedures for rapid improvement.

Variation of Condensed Tannins in Roundhead Lespedeza Germplasm

ABSTRACTRoundhead lespedeza, Lespedeza capitata Michx., is a deep‐rooted, perennial legume native to the eastern and central USA and is relatively common on remnant upland prairies throughout the Midwest. Information on condensed tannin (CT) concentrations from different plant parts is needed for cultivar development and also to provide data for developing management and feeding strategies. The objectives of this study were to determine variation of CT concentrations in roundhead lespedeza leaves, stems, and inflorescences; evaluate genotype variation over environments; and select germplasm lines that could be used for breeding parents and/or bulked into a synthetic variety. Thirty‐nine roundhead lespedeza plant introductions (PI) were sampled from replicated nurseries grown in two environments in 1996. Plant shoots were collected at flowering and seed filling. Each plant shoot sample was divided into leaf, stem, and inflorescence. Condensed tannin concentrations were determined by means of a modified vanillin–HCl method. We found that variation due to the environment was low, variation due to genotype was high, and variation due to genotype × environment interaction was high. Of these 39 plant introductions, we selected eight that were common to both environments and had low CT concentrations in leaves at flowering. The CT content of these plant introductions, however, was still relatively high when compared with sericea lespedeza [Lespedeza cuneata (Dumont) G. Don] that was bred for low tannin content. Collections should be made from a larger geographical region to look for germplasm with lower CT concentrations.

Effect of dietary sorghum cultivars on the storage stability of broiler breast and thigh meat

A total of 450 1-d-old male broiler chicks were fed a corn-soy-flax meal-based diet (control), two cultivars of sorghum-Ruby Red (low tannin content) and Valpo Red (high tannin content)–were used at 10% level. Birds were slaughtered at the end of 42-d feeding trial. Boneless, skinless breast and thigh muscles were separated and ground to make patties. Half of the breast and thigh meat patties were individually packaged in zipper bags, and 2-TBA-reactive substances (TBARS) and colors of the patties were determined after 0 and 7 d of storage at 4 C. The other half was cooked and vacuum-packaged. The vacuum-packaged patties were used to determine time-dependent volatile production and oxidative change during 12-h holding time before analyses. Thigh meat from broilers fed the Valpo Red cultivar produced lower TBARS than that from control at Day 0. The amounts of aldehydes and sulfur compounds of cooked breast meats were lower from chickens fed the Valpo Red cultivar than those fed the control or Ruby Red cultivar. Dietary Valpo Red cultivar improved the oxidative stability of breast meat 8 and 12 h after cooking. Dietary sorghum slightly improved the color a* stability of raw thigh meat patties. This result indicated that feeding sorghum to broilers could improve some measures of the storage stability of broiler meat, but sorghum with high tannin content was more effective than that with low tannin content.

The effect of food quality and relative abundance on food choice in fallow deer

The diet choice of large herbivores is influenced by the presence of nutrients and toxins in available plants. It is generally assumed that herbivores ingest food that contains higher amounts of nutrients and lower amounts of toxins than the average of the food available. We studied the effects of quality and relative abundance on food choice in fallow deer,Dama dama . Preferences for and aversions against different compounds were first examined in two-choice tests with food and water. We then did cafeteria (multiple-choice) tests with hydrolysable tannin and sucrose added to food to investigate the influence of the frequency of occurrence. We found that food choice was biased towards lower tannin content. Consumption with respect to tannin content was relative rather than absolute, however, in that the intake of a given concentration depended on which other concentrations were present. In addition, the relative preference for low-tannin food was weaker in the cafeteria test, where this food had a smaller frequency of occurrence, indicating that frequency of occurrence influences food choice. We discuss these results from the perspective of optimal foraging theory and suggest that a changing and complex distribution of food types in nature may make it advantageous for large herbivores to show intermediate selectivity, rather than attempting to ingest only the highest quality food possible. Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.

Breakdown of leaf litter in a neotropical stream

We investigated the breakdown of 2 leaf species, Croton gossypifolius (Euphorbiaceae) and Clidemia sp. (Melastomataceae), in a 4th-order neotropical stream (Andean Mountains, southwestern Colombia) using leaf bags over a 6-wk period. We determined the initial leaf chemical composition and followed the change in content of organic matter, C, N, and ergosterol, the sporulation activity of aquatic hyphomy cetes, and the structure and composition of leaf-associated aquatic hy phomy cetes and macroinvertebrates. Both leaf species decomposed rapidly ( k 5 0.0651 and 0.0235/d, respec- tively); Croton lost 95% of its initial mass within 4 wk compared to 54% for Clidemia . These high rates were probably related to the stable and moderately high water tempera ture (19 8 C), favoring strong biological a ctivity. Up to 2300 and 1500 invertebrates per leaf bag were found on Croton and Clidemia leaves after 10 and 16 d, respectively. Shredders accounted for , 5% of the total numbers and biomass. F ungal biomass peaked at 8.4 and 9.6% of the detrital mass of the 2 leaf species, suggesting that fungi contributed cons iderably to leaf mass l oss. The difference in breakdown rates between leaf species was consistent with the earlier peaks in ergosterol and sporulation rate in Croton (10 d vs 16 d in Clidemia ) and the faster colonization of Croton by macroinvertebrates. The softer texture, lower tannin content, and hi gher N content were partly responsible for the faster breakdown of Croton leaves. The rapid breakdown of leaf litter, combined with a low infl uence by shredders, is in accordance with previous findings. The high fungal activity associated with rapid leaf breakdown appears to be characteristic of leaf processing in tropical streams.

Investigation of some Hypericum species native to Southern of Brazil for antiviral activity

Three plant species, Hypericum connatum, Hypericum caprifoliatum, Hypericum polyanthemum (Guttiferae), growing in Southern of Brazil were chemically investigated and tested for their antiviral activity against feline immunodeficiency virus (FIV). The chemical analysis revealed the presence of polyphenolic compounds such as tannins and flavonoids. Hypericin was not detected in these species. The aqueous extract (AE), the aqueous extract with low tannin concentration (LTCAE) and the methanolic extract (ME) were tested for their cytotoxic properties in concentrations of 50–150 μg/ml. AE was toxic to CRFK for the three species in all concentrations. LTCAE and ME varied between different concentrations being not toxic or allowing 80% of cell growth. LTCAE and ME (10–50 μg/ml) were analyzed for antiviral activity by inhibition of CPE and measuring FIV genome from cell culture supernatant. LTCAE of all species in this work did not cause any inhibition of FIV. Although no difference was seen in CPE, a lower number of viral particles in the supernatant was observed when FIV infected cells were treated with ME of H. connatum. These results suggest that some plants of the genus Hypericum from Southern Brazil contain compounds with potential antiviral activity against lentiviruses.

Cyanic acid, Phytic acid, total tannin and aflatoxin contents of a Brazilian (Natal) multimistura preparation

The utilization of a "multimistura" as food supplement, in nutritional improvement programs for the low-income population in Brazil, represents a low-cost and easy-to-use food preparation alternative, presentig reasonable nutritive value and satisfying local taste preferences. This is based on the fact that the "multimistura" is made up of non-conventional ingredients/foods and of agroindustrial by-products, rich in different nutrients. This paper was designed to determine some toxic and/or antinutritional factors of a "Multimistura" utilized as food supplement in institutional programs to prevent malnutrition by the Department of Welfare and Social Affairs of the City of Natal, RN. The product studied had the following formulation: 30% of wheat bran; 30% of wheat flour; 30% of corn meal; 3% of powder from cassava leaves; 4% of pumpkin seeds powder; and 3% of eggshell powder. The analysis of the main toxic and/or antinutritional factors showed very low concentrations of phytates and tannins and no detectable levels of aflatoxin and cyanic acid.

Comparison of the digestive ability of crop fluid from the folivorous Hoatzin ( Opisthocomus hoazin) and cow rumen fluid with seven tropical forages

We explored the hypothesis that the Hoatzin, a tropical bird which feeds on tree leaves and has a crop resembling a rumen, may have a better ability to digest tanniniferous feeds than do cattle. Comparisons were made between Hoatzin crop fluid (HCF) and cow rumen fluid (CRF) in in-vitro digestion studies using freeze dried leaves of six tropical tanniniferous shrub legumes and the tropical grass Panicum maximum. In-vitro dry matter digestibility (IVDMD) and in-vitro nitrogen digestibility (IVND) were measured in the presence and absence of polyethylene glycol (PEG) to minimise the effect of condensed tannin. For all plant species, and in the presence or absence of PEG, the CRF gave higher IVDMD and IVND than did HCF ( P<0.01). The interaction of PEG×animal ( P<0.01) for IVDMD was due to an absence of response with CRF (62.1 v 63.0%) and a large response with HCF (43.5 v 37.4%). Similarly for IVND, the response to PEG with CRF was much smaller (83.4 v 75.6%) than for HCF (51.9 v 26.5%) ( P<0.01). PEG had no significant effect on IVDMD or IVND of the CT-free Panicum maximum by HCF or CRF ( P>0.05). However, values were much higher with CRF: 74.2 v 30.6% and 81.3 v 29.0%, respectively. The only legume to have reasonable levels (>55%) of IVDMD and IVND with HCF in the absence of PEG was Gliricidia sepium, which has little or no free condensed tannins. Acacia boliviana, Calliandra calothyrsus and Leucaena trichandra gave low values and those for L. leucocephala and L. pallida were intermediate. The low IVDMD and IVND with HCF, together with the large response to PEG, clearly show that high tannin content in the diet cannot be handled by the Hoatzin. Low tannin content in the crop contents indicates that it avoids highly tanniniferous leaves. This supports other findings that the Hoatzin is extremely selective of a high quality leafy diet. It is concluded that the Hoatzin is an unlikely source of bacteria to improve the feeding value of tropical tanniniferous shrub legumes for cattle.

Research on Trace Minerals in the Common Bean

The common bean (Phaseolus vulgaris L.) is the most important grain legume for direct human consumption, being especially important in eastern Africa and in Latin America. The objective of the Centro Internacional de Agricultura Tropical (CIAT) in participating in the Consultative Group on International Agricultural Research (CGIAR) Micronutrients Project has been to assess the feasibility of improving common beans for micronutrient content, especially iron and zinc. In the evaluation of more than a thousand accessions in the cultivated core collection, a mean iron concentration of 55 mg/kg was found, with a range of 34 to 89 mg/kg. Zinc concentrations ranged between 21 and 54 mg/kg, with an average value of 35 mg/kg. These initial data suggest that sufficient genetic variability exists to improve iron content by about 80% and zinc content by about 50%. An essential question for the improvement of any trait through plant-breeding is the degree to which the trait is stable across environments. Genetic differences have been expressed over environments and seasons, offering good prospects that genotypes selected in one environment for high iron or zinc will express superior levels of minerals in other environments as well. Correlations among mineral concentrations suggest that the improvement of one mineral may simultaneously improve the contents of other minerals, thus multiplying the impact of the effort. The fact that the bioavailability of iron was higher in white beans in rat studies suggests that a lower tannin content could be beneficial, but the role of tannin is still not well elucidated. The genetics of iron and zinc content appears to be complex, involving between 7 and 11 loci.

Relationship between phospholamban and nucleotide activation of cardiac sarcoplasmic reticulum Ca2+ adenosinetriphosphatase.

A strong connection with nucleotide activation of Ca2+ATPase and phospholamban inhibition has been found. Phospholamban decreases the number of activatable Ca2+ATPase without affecting substrate affinity or the ability of nucleotide to serve its dual modulatory roles, i.e., catalytic and regulatory. Low concentrations of certain nucleotide mimetics, quercetin, tannin, and ellagic acid, with structural similarity to adenine can unmask phospholamban's inhibitory effect while concurrently acting as competitive inhibitors of nucleotide binding. Micromolar concentrations of tannin (EC50 approximately 0.3 microM) and ellagic acid (EC50 approximately 3 microM) stimulated Ca2+ uptake and calcium-activated ATP hydrolysis at submicromolar Ca2+ in isolated cardiac sarcoplasmic reticulum (SR). Stimulation of Ca2+ATPase was followed by pronounced inhibiton at only slightly higher tannin concentrations (IC50 approximately 3 microM), whereas inhibitory effects by ellagic acid were observed at much greater concentrations (IC50 > 300 microM) than the EC50. A complex relationship between compound, SR protein, and MgATP concentration is a major determining factor in the observed effects. Stimulation was only observed under conditions of phospholamban regulation, while the inhibitory effects were observed in cardiac SR at micromolar Ca2+ and in skeletal muscle SR, which lacks phospholamban. Maximal stimulation of Ca2+ATPase was identical to that observed with the anti-phospholamban monoclonal antibody 1D11. Both compounds appear to relieve the Ca2+ATPase from phospholamban inhibition, thereby increasing the calcium sensitivity of the Ca2+ATPase like that observed with phosphorylation of phospholamban or treatment with monoclonal antibody 1D11. Tannin, even under stimulatory conditions, is a competitive inhibitor of MgATP with a linear Dixon plot. The subsequent inhibitory action of higher tannin concentrations results from competition of tannin with the nucleotide binding site of the Ca2+ATPase. In contrast, ellagic acid produced a curvilinear Dixon plot suggesting partial inhibition of nucleotide activation. The data suggest that nucleotide activation of Ca2+ATPase is functionally coupled to the phospholamban interaction site. These compounds through their interaction with the adenine binding domain of the nucleotide binding site prevent or dissociate phospholamban regulation. Clearly, this portion of Ca2+ATPase needs further study to elucidate its role in phospholamban inhibition.

Nitrogen in browse species: ruminal degradability and post-ruminal digestibility measured by mobile nylon bag andin vitro techniques

This study determined nitrogen degradability and digestibility of rumen undegradable nitrogen using mobile nylon bag (MNB) and pepsin/pancreatin in vitro technique (IV) of 40 browse species. Thirty Ethiopian highland sheep fitted with rumen cannulae were used in nitrogen (N) degradability studies. Six steers fitted with rumen cannulae were used in preparation of 16-h and 24-h ruminal undegraded residues and four steers fitted with distal abomasal cannulae were used in MNB technique. The browses varied widely in nitrogen solubility (15–468 g kg−1), potential degradability (223–976 g kg−1), rate of degradation (0·13–24% h−1) and effective degradability (135–821 g kg−1). The apparent N digestibility (ND) of the rumen undegraded residues differed significantly (P<0·05) among browse species. No significant difference (P>0·05) was observed in ND of 16-h and 24-h residues. The ND of the 16-h residue varied from -218 to 759 g kg−1 and 169 to 851 g kg−1 for MNB and IV methods, respectively. Browse species with high tannin contents such as Acacia hockii, A horrida, A melanoxylon, A persiciflora, A salicina, A saligna and Flemingia macrophylla had high rumen by-pass and a low ND, while Sesbania spp and A nilotica with low tannin contents underwent rapid and extensive dry matter and nitrogen degradation in the rumen. Acacia sieberiana, Chamaecytisus palmensis, Erythrina spp, Gliricidia sepium, Samanea saman and Enterolobium cyclocarpum had high proportions of protein escaping rumen degradation (BP) and with a high proportion of the by-pass protein digested in the intestine, therefore these browses had a high potential as protein supplements. The ND measured with the MNB were significantly lower (P<0·001) than by the IV method. The correlation between MNB and IV was high and significant (R2=0·89, P<0·0001) as also indicated by the regression equation (SE in parentheses): MNB=-22·8 (4·55)+1·0 (0·08)IV (RSD=10·56, R2=0·79, n=40, P<0·001). The intercept of the linear relationship obtained was different from zero while the slope was not different from unity. Multiple regression analysis suggested that some of the unexplained variation could be accounted for by either nitrogen, acid detergent fibre, total phenolics or neutral detergent fibre bound tannin levels in browses. The IV method is accurate for estimating digestibility of ruminally undegradable N, and hence its use would considerably reduce the need for delicate surgery and the elaborate procedures involving the MNB technique. © 1998 SCI.

Evolution of Phenolic Compounds in Red Winemaking as Affected by Must Oxygenation

In a preliminary study we followed the evolution of anthocyanins and other phenolics during the fermentation of red Sangiovese grapes (no SO₂ added) which were treated with two different amounts of oxygen prior to fermentation. Musts to which oxygen had been added showed a consistent decrease in red pigments, anthocyanins, hydroxycinnamyl tartaric acids and total phenolics during the skin contact compared to the not oxygenated control. After six months of storage, the oxygenated trials exhibited a lower content of tannins, catechins, and total anthocyanins, a reduced color density and an higher percentage of polymeric pigment compared to the control wine. Significant sensory differences were found among wines; the most preferred wine was that obtained with limited oxygenation in the prefermentative phase (75 mL/kg) due to its low astringency and good balance.

Induced mutations in winged bean (Psophocarpus tetragonolobus L. DC) with low tannin content

Four mutants of winged bean (Psophocarpus tetragonolobus (L.) DC) with altered tannin content were selected among the M3 seeds present on M2 plants following mutagenic treatment of seeds of cvs UPS 122 and Kade 6/16 using gamma radiation from a Co60 gamma source. These mutants were selected from the most chimeric parts of the M1 plant, which had earlier been identified to be the first mature pods on the M1 plant and the earliest formed M2 seeds in the M1 pods. The indirect selection of tannin mutants was based on searching for seed coat colour changes in M3 seeds. Cv UPS 122 yielded the mutants 3/1-10-12 and X22 from 1958 and 1883 M2 plants respectively. Cv Kade 6/16 yielded the mutants 3/9-0-12 and 3/4-10-7 from 1442 and 1011 M2 plants respectively. One of the mutants, 3/4-10-7, which was the only desirable one, had a level of tannin of about 25% of the wild type cv. Kade 6/16. The other three mutants had similar or increased tannin levels.

In Situ Disappearance of Individual Proteins and Nitrogen from Legume Forages Containing Varying Amounts of Tannins

In situ degradability of N and proteins were studied in one cultivar of alfalfa and red clover and two cultivars each of birdsfoot trefoil and sericea lespedeza. Concentrations of tannic acid equivalents (percentage of DM) were 0.68 in one cultivar of birdsfoot trefoil and 1.77 and 2.78 in the two cultivars of lespedeza. The other forages contained essentially no tannins. Forage samples were digested in situ for 0, 2, 4, 6, and 12h. The amount of N remaining at 12h was positively correlated with concentrations of tannin. About 38% of the N remained after 12h in forages with no or low concentrations of tannins, and 86% remained in the two cultivars of lespedeza. Total electrophoretically identified proteins followed similar trends, but the percentage remaining was less than that for N. For all forages, bands were found at molecular masses of 15, 30, 45, 47, and 54 kDa. The percentage of 54-kDa protein that remained after 12h was less than that for the other four proteins (23% vs 37%). No interaction was found between forage cultivar and protein species. These results showed that tannins reduced ruminal degradation of proteins and that specific forage proteins degraded at different rates that were independent of tannin concentration.

Physicochemical and Structural Properties of Two Bean Varieties which Differ in Cooking Time and the HTC Characteristic

Physicochemical and structural properties as well as proneness to hardening were assessed in normal (Mayocoba) and slow (Flor de Mayo) cooking varieties of beans. Storage and chemical procedures were used for determination of the hardening of both samples. Normal and slow cooking varieties had cooking times of 58 and 90 min, respectively. During storage under high temperature and humidity the normal variety exhibited a four-fold increase in cooking time while that of the slow cooker increased nine-fold. Chemical hardening caused an increase in cooking time of 3.4- and 5.7-fold for normal and slow beans, respectively. The former had lower percentage and thinner seed coat, and higher water absorption in the whole seed and seed coat, but not in the cotyledons, as compared to the latter. Chemical analysis demonstrated a much lower tannin content in fresh and hardened seed coats and cotyledons of the normal cooker, but more phytic acid content in cotyledons than in the slow. In fresh and hardened states the normal cooking variety had lower gelatinization and protein denaturation temperatures and enthalpies than the slow. SEM revealed important structural differences between both varieties and conditions. These characteristics may be used as identifying features linked to hardening proneness.