Sodium Hydroxide Enhances Extractability and Analysis of Proanthocyanidins in Ensiled Sainfoin (Onobrychis viciifolia).
Little information exists on the effects of ensiling on condensed tannins or proanthocyanidins. The acetone-butanol-HCl assay is suitable for measuring proanthocyanidin contents in a wide range of samples, silages included, but provides limited information on proanthocyanidin composition, which is of interest for deciphering the relationships between tannins and their bioactivities in terms of animal nutrition or health. Degradation with benzyl mercaptan (thiolysis) provides information on proanthocyanidin composition, but proanthocyanidins in several sainfoin silages have proved resistant to thiolysis. We now report that a pretreatment step with sodium hydroxide prior to thiolysis was needed to enable their analysis. This alkaline treatment increased their extractability from ensiled sainfoin and facilitated especially the release of larger proanthocyanidins. Ensiling reduced assayable proanthocyanidins by 29%, but the composition of the remaining proanthocyanidins in silage resembled that of the fresh plants.
Chemistry and Biochemistry Laboratory, School of Agriculture, Policy and Development, University of Reading , 1 Early Gate, P.O. Box 236, Reading RG6 6AT, United Kingdom.
Aina
A
Ramsay
Chemistry and Biochemistry Laboratory, School of Agriculture, Policy and Development, University of Reading , 1 Early Gate, P.O. Box 236, Reading RG6 6AT, United Kingdom.
Chris
C
Drake
Agroscope, Institute for Livestock Sciences, Route de la Tioleyre 4, 1725 Posieux, Switzerland.
Anja
A
Grosse Brinkhaus
Agroscope, Institute for Livestock Sciences, Route de la Tioleyre 4, 1725 Posieux, Switzerland.
Marion
M
Girard
INRA, UMR 1213 Herbivores , F-63122 Saint-Genès-Champanelle, France.
Giuseppe
G
Copani
Agroscope, Institute for Livestock Sciences, Route de la Tioleyre 4, 1725 Posieux, Switzerland.
Frigga
F
Dohme-Meier
Agroscope, Institute for Livestock Sciences, Route de la Tioleyre 4, 1725 Posieux, Switzerland.
Giuseppe
G
Bee
INRA, UMR 1213 Herbivores , F-63122 Saint-Genès-Champanelle, France.
Vincent
V
Niderkorn
Chemistry and Biochemistry Laboratory, School of Agriculture, Policy and Development, University of Reading , 1 Early Gate, P.O. Box 236, Reading RG6 6AT, United Kingdom.
Irene
I
Mueller-Harvey
D005591:Chemical Fractionation / Q000379:methods*; D007887:Fabaceae / Q000737:chemistry* / Q000378:metabolism; D010936:Plant Extracts / Q000032:analysis / Q000302:isolation & purification* / Q000378:metabolism; D044945:Proanthocyanidins / Q000032:analysis / Q000302:isolation & purification* / Q000378:metabolism; D012972:Sodium Hydroxide / Q000737:chemistry*
D010936:Plant Extracts; D044945:Proanthocyanidins; C013221:proanthocyanidin; D012972:Sodium Hydroxide
alkaline pretreatment; reaction products; silage; thiolysis; unextractable tannins