Extraction of oligosaccharides and phenolic compounds by roasting pretreatment and enzymatic hydrolysis from spent coffee ground

Spent coffee ground (SCG) is the waste generated during the preparation of instant coffee and is the sourceof industrially valuable organic compounds. In this article, SCG was pretreated by roasting at 150°C for 30minutes and heated with water at 90°C for extracting carbohydrates and phenolic compounds, after which1.0% (w/w) β-mannanase was applied for the hydrolysis of pretreated SCG. SCG is characterized in terms ofits total sugar content by the anthrone–sulfuric assay and phenolic compounds by Folin−Ciocalteu’s procedure.In this study, the total sugar increased by 14.79% (w/w) by the roasting process, and subsequently enzymatichydrolysis increased the total sugar yield up to 17.43% (w/w) compared to the untreated SCG, i.e., 10.24%(w/w). The reducing sugar was estimated by the dinitrosalicylic acid method and the end product increased to106.10 (mg Glucose/g) from the initial content 5.32 (mg Glucose/g raw SCG). The total phenolic compoundincreased to 291.86 (mg Gallic acid/g lyophilized material), which was a 6.39-fold increase compared to thenative SCG (45.68 mg Gallic acid/g). These results point to the valuable compounds present in SCG, can beenhanced by combining the roasting pretreatment and enzymatic hydrolysis, and can be utilized in the foodand biotech industries.

Size exclusion chromatography for the removal of pigments from extracellular ligninolytic enzyme extracts from decayed wheat straw.

Solid-state fermentation of wheat straw was carried out by a native white rot basidiomycete Daedaleopsis flavida strain 5A. Extract prepared from the 12-day decayed wheat straw contained extracellular ligninolytic enzymes like manganese peroxidase (MnP), manganese-independent peroxidase (MIP), lignin peroxidase (LiP) and laccase along with straw-degraded products and pigments. Sephacryl S-200 size exclusion chromatography in 16/100 column was used for the separation of these ligninolytic enzymes and strawdegraded products and pigments. Recovery of pigment-free ligninolytic enzyme activities as protein was 40% of the total proteins loaded and specific LiP activity increased 34 fold after size exclusion chromatography. Thus accurate estimation of LiP by veratryl alcohol oxidation assay was possible only after the removal of interfering pigments. The reproducibility of size exclusion chromatography is adjudged satisfactory from the consistent results obtained after seven repetitive uses of matrices.