Extraction process of soluble proteins from discarded tobacco leaves
This study innovatively combined ultrasonic extraction,ultrafiltration,and weakly alkaline isoelectric precipitation technologies to devise a process for the efficient ex-traction of soluble proteins from discarded tobacco leaves.Additionally,a comprehensive evaluation system incorporating physical,chemical,and biological parameters was estab-lished.By optimizing the process,an effective protocol was identified as follows.A pH 7.85 phosphate buffer at a concentration of 0.085 mol/L was utilized for ultrasonic ex-traction with a material-to-liquid ratio of 1∶8.Subsequently,fractionated centrifugation and filtration/ultrafiltration were performed,followed by adjustment of the solution to an isoelectric point pH of 5.5 using a 0.11 mol/L[H+]solution.This protocol facilitated the successful extraction of mixed proteins with molecular weights of approximately 55 kDa and exceeding 200 kDa.The amino-acid composition of the extracted proteins satisfied the essential amino-acid requirements of adults.Infrared-spectrum analysis indicated the absence of significant pectin or polysaccharide features.This research introduced a gentle,weakly alkaline isoelectric point extraction approach,combined with physical-extraction techniques.This method not only overcomes the limitations of conventional extraction processes but also exhibits broad applicability.Innovative pathways are presented herein for the resourceful utilization and industrial-scale production of discarded tobacco leaves.
tobacco leaf proteinphosphate buffer systemultrafiltrationnicotineisoelectric point
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