Titrable groups and soluble phenolic compounds in untreated and treated mustard (Brassica campestris) straw and their relation with cell wall constituents and dry matter disappearance in situ

Abstract

The mustard straw (MS) was soaked for 6 hr in solutions containing ditferent combinations of sodium hydroxide (0. 1 and 2 % w/v) and hydrogen peroxide (0 and 1,5 % v/v) in 3x2 factorial design with 3 replications to study the relationship of titrable groups and that of dissociable and residual phenolic acids with cell wall constitucnts and nylon bag dry matter disappearance (NBOMD) of mustard straw. The oven dried (50°C) samples of untreated and treated MS (UMS and TMS) were analyzed for titrable groups (TG. meq of acid/g). the dissociated phenolic compound rendered soluble in neutral detergent solution i.e. dissociable phenolic units (DPU, O₂₈₀/mg/ml) and those insoluble in neutral detergent solution but dissolved in sodium hydroxide i.e. residual phenolic units (RPU, OD₂₈₀/mg/ml) were analyzed in addition to neutral detergent fibre (NDF), acid detergent fibre (ADF). acid detergent lignin (ADL) and nylon bag dry matter disappearance (NBOMD). The TG and RPU had highly.positive correlation with NDF and ADF. while DPU had high negative correlation with NDF and ADF. The ADL content of samples was poorly correlated with TG. RPU and DPU. The TG and RPU had high negative correlation (P<0.001) with NBDMO. Thc DPU. howcver. had positive correlation with NBDMD. It is concluded that measurement ofTG and RPU can be used for assessing the effectiveness of different chemical treatments as it relates well with NBDMD. Both the sodium hydroxide (2%) and alkaline hydrogen peroxide (2% NaOH + 1.5% H₂O2) treatment of mustard straw decreased TG and RPU.