Innovative Nanofibrillated Cellulose from Rice Straw as Dietary Fiber for Enhanced Health Benefits Prepared by a Green and Scale Production Method

Increased focus has been directed toward the use of agricultural residues. Conversion of lignocellulosic biomass to nanocellulose, such as nanofibrillated cellulose (NFC) has prompted a revolution in biobased materials for diverse applications. Currently used chemical methods for the preparation of NFC are not environmentally friendly and even exhibit toxicity, limiting the application of NFC in food. The present study proposes an innovative NFC as dietary fiber, prepared using a green and scale production method. This technique provides an integrated approach that combines physicochemical pretreatment (high-density steam flash explosion, HDSF at 2.0 MPa) and successively enzymatic catalysts (45 U/g xylanase for 3 h, 60 U/g lactase for 4 h, and 150 U/g cellulose for 12 h) for the conversion of rice straw into NFC which is characterized by long and distinct fibrillated cellulose with widths of 30-200 nm, exhibiting excellent water retention capacity (20 g water/g) and swelling capacity (105 mL/g). Based on the NFC, hydrophobic groups (octenyl succinic anhydride, OSA) were further grafted onto the surface of NFC to prepare an innovative OSA NFC as dietary fiber with enhanced health benefits (such as bile acids, cholesterol, nitrite ion, and oil/fat adsorption), especially which could markedly increase the adsorption capacity for oil in vitro (17.8 g oil/g after digestion model) and in vivo (almost 500 mg fat/g feces of rats). OSA NFC could be used as high quality dietary fiber with a strong ability to absorb oil to help regulate body weight, representing an innovative way of transforming cheaper biomass into value-added products.