Changes in free and bound fractions of aroma compounds of four Vitis vinifera cultivars at the last ripening stages.

The volatile composition of white Agudelo, Blancolexitimo, Godello and red Serradelo cultivars (NW Spain) harvested at two different stages of ripening have been evaluated. C(6)-compounds, alcohols, volatile fatty acids, monoterpenes, C(13)-norisoprenoids, volatile phenols and carbonyl compounds were identified and quantified in free and glycosidically bound forms by gas chromatography-mass spectrometry (GC-MS). The total volatile concentration showed a significant increase between the two ripening stages studied for all cultivars.

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.

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.