Lignin studies I. Investigations concerning lignin determination

Abstract

In this investigation a sulphuric acid method for the determination of lignin is presented and the influence of various details critically studied. The samples ground to pass through a 60 mesh (0.25 mm.) screen gave 0—5 % smaller results than those ground through an 1 mm. screen. Locating the extraction with ethanol-benzene before or after the prehydrolysis had no significant influence on the lignin values. The refluxing with water before the acid prehydrolysis lowered the lignin values (N-free) to some extent. The pepsin pretreatment lowered them still further. The nitrogen content of the part of crude lignin which was digested by pepsin was 9—13 %. On the nitrogen content of crude lignin obtained from faeces the use of pepsin had no influence. The hydrolysis procedure with 72 per cent sulphuric acid did not appear to be conventional as to the extension of the hydrolysis above the time needed, the effeciency of the stirring of the mixture or the stability of the temperature. The refluxing of the dilution after 72 per cent acid treatment was not necessary if the acid prehydrolysis was sufficiently effective. The lignin values obtained by different acid methods correspond to each other provided that certain fundamental principles are followed.

Determination of carbohydrates in animal foods as seven fractions

“…The lignin values are somewhat larger than those obtained by the methods with a stronger prehydrolysis (Salo, 1957). It is, however, difficult to decide which method would give the most exact result.…”

Etude de la prévision de la digestibilité des fourrages par une méthode enzymatique

“…L'essentiel des résultats obtenus à l'LN.R.A. pour les fourrages verts a été présenté dans les « Tableaux de la valeur alimentaire des fourrages (DEnznxQmLLY & W EISS , 1970) (DoNEEER!et al, 1963 ;J ONES & H AYWARD , 1975 (S ALO , 1957 ;J ARRIGE , 1961 ; VAN S OEST , 1967 The correlation between in vivo organic matter digestibility and pepsin-cellulase digestibility were markedly improved by pre-treatment of herbage with acid-pepsin (RSD = 0.036 with pepsin, RSD = 0.041 without pepsin), but no significant effect could be found of acid concentration from 0.1 to 1 N in pepsin solution ( figure 1 a), though values obtained at 1 N concentration were closer to those obtained in vivo. The accuracy of the prediction by the pepsin-cellulase method was not improved when temperature was increased from 40° to 50° or when incubation time was 48 h instead of 24 h (table 3).…”

Lignin studies III. Lignin as tracer in digestibility investigations

“…In this laboratory lignin has been used as tracer in investigations concerning the transport of food in the alimentary canal and the extent of digestion in different parts of the alimentary tract (20,17). The lignin was determined by three modifications (a, b, c) of the method (method A) described in a previous paper (26). This method includes a protein correction for crude lignin.…”