Antón Masa

Digestibility of silages in relation to their hydroxycinnamic acid content and lignin composition

BACKGROUND The effectiveness of the analysis of cell wall-bound hydroxycinnamic acids and the composition of lignin to evaluate the in vivo digestibility of a silage collection with unknown botanical composition was evaluated. RESULTS Syringyl units content and total etherified phenols showed the highest correlation coefficients with in vivo dry matter digestibility (IVDMD) (r = - 0.792 and r = - 0.703, respectively), while guaiacyl units and total phenols showed the highest correlation coefficients with in vivo organic matter digestibility (IVOMD) (r = - 0.871 and r = - 0.817, respectively). Using the above-mentioned chemical parameters, 10 equations were also developed to predict in vivo digestibility. The prediction of IVDMD produced a high adjusted R(2) value (0.710) using syringyl, total lignin, etherified total phenols, esterified ferulic acid and total phenol content as predictors. The prediction of IVOMD produced a higher adjusted R(2) value (0.821) using guaiacyl, total phenols, total ferulic acid and etherified p-coumaric acid content as predictors. CONCLUSION Cell wall digestibility depends on a multiplicity of factors and it is not possible to attribute a causal effect on in vivo digestibility to any single factor. However, syringyl and guaiacyl content and etherified phenols emerge as good predictors of digestibility.

Evaluation of the aroma descriptors variability in Spanish grape cultivars by a quantitative descriptive analysis

Aroma descriptors variability was evaluated by quantitative descriptive analysis (QDA) in Spanish cultivars. Abariño, Mencía and Godello cultivars were evaluated by three expert panels by using monovarietal wines. The frequency and intensity of aroma descriptors was evaluated and geometric mean (GM) was calculated. The largest differences between cultivars were shown by principal component analysis (PCA). Albariño cultivar was characterised by Ripe fruit, Apple and Fruit descriptors; Mencía cultivar was Balsamic and Red fruit, while Citric, Grass, Pineapple, Toasting, Tropical, Dry grass, Pear, Melon and Floral were the attributes of the Godello cultivar. According to GM obtained of aroma attributes from, a positive correlation was found between Albariño and Godello cultivars. The QDA and PCA have contributing to define the aroma of different Spanish grape cultivars (Albariño, Mencía and Godello) by analysis of the monovarietal wines. The results obtained suggest that QDA is a good tool to evaluate the sensory variability of a product, when the tasting panel is good trained.

Relationship between hydroxycinnamic acid content, lignin composition and digestibility of maize silages in sheep.

Cell wall-bound hydroxycinnamic acids and the composition of lignin were studied in relation to the digestibility of a collection of 91 maize silages in wethers. Total lignin and guaiacyl content showed the highest correlation coefficients with digestibility. Using the above-mentioned chemical parameters, eight equations were also developed to predict digestibility. The prediction of organic matter digestibility produced a high adjusted R 2 value (0.487) using total lignin, guaiacyl, esterified ferulic acid and esterified p-coumaric acid content as predictors. The prediction of in vivo dry matter digestibility produced a higher adjusted R 2 value (0.516) using the same variables as predictors. Cell wall digestibility depends on a multiplicity of factors and it is not possible to attribute a causal effect on in vivo digestibility to any single factor. However, total lignin, guaiacyl and p-coumaric acid content emerge as good predictors of digestibility.