Development of bio-mechanical rice straw pulp by high consistency kneader with thermal and Alkaline.

The purpose of this study was to develop a bio-mechanical pulp from rice straw with thermal and low chemical dosage. The process is carried out by thermal alkali kneading pretreatment (0-5% NaOH) with a high concentration kneader, enzyme pretreatment (0.2-4%) and Hollander beater. The results showed that the addition of NaOH was the main factor affecting the properties of pulp and paper, and the best properties of straw pulp could be obtained when NaOH and enzyme dosage were 5% and 0.2%, respectively. Although the optimum rice straw pulp is inferior to straw soda pulp in terms of tensile, burst and ring crush index, it is superior to old corrugated cardboard pulp and partially meets the CNS standards of corrugated medium paper and linerboard without the addition of chemicals. Therefore, the bio-mechanical rice straw pulp in this study has the potential to be produced as industrial paper.

Feasibility of substituting old corrugated carton pulp with thermal alkali and enzyme pretreated semichemical mechanical rice straw pulp.

In this study, we separately used a laboratory Hollander beater, a pilot scale 12″ single-disc refiner and an expanded trial with a commercial paper mold mill to investigate the feasibility of using thermal-alkali/enzyme pretreated rice straw semi-chemical mechanical pulp to substitute portions of old corrugated carton board (OCC) pulp in the paper industry. In the laboratory plan, sequential treatments of NaOH at a 5-10% dosage and enzymes at a 0.2-4% dosage were applied to rice straw, followed by beating using a Hollander beater for 1-2 h to complete the rice straw semi-chemical mechanical pulping process. When the NaOH dosage, enzyme dosage and refining time were 10%, 0.2% and 1 h, the best quality rice straw pulp was obtained. Along with the increase in NaOH dosage, the pulp freeness decreased significantly, and the pulp accepted rate increased. Enzymatic treatment enhanced rice straw quality only after NaOH dosage treatment, which then reacted with rice straw to increase the quality of pulp. In the expanded trial, the rice straw semi-chemical mechanical pulp was blended with OCC pulp (0%, 25%, 50%, 75% and 100%) to form handsheets. Along with an increase in rice straw proportions, the tensile index, burst index, and ring-crush index increased by 109-200%, 13-196%, and 124-187%, respectively. In an online commercial paper mold mill trial, blending rice straw pulp with OCC could successfully make paper-mold egg cartons, with both mill operation and product smoothness appearance being highly acceptable.

Production of functional peptides with inhibition ability against angiotensin I-Converting enzyme using P. pastoris expression system.

To obtain the angiotension-I converting enzyme inhibitor (ACEI), a fusion ACEI polypeptide encoded with 8 DNA sequences of GPL, GPM, IKW, IVY, IRPVQ, IWHHT, IYPRY and IAPG, which were selected and designed and cloned into pGAPZαC and then transformed into Pichia pastoris SMD1168H. After 3 days induction, the fraction with highest ACEI activity was expressed and purified using a Ni Sepharose™ 6 Fast Flow. The IC50 of recombinant ACEI polypeptide was 88.2 µM. A 128-fold increase of ACEI activity (0.69 µM) was obtained after pepsin digestion, which was equivalent to 0.022 µM of captopril. Reverse phase HPLC indicated all the 8 peptides contained in ACEI-hydrolysate after pepsin digestion.