Utilization of Acai Berry Residual Biomass for Extraction of Lignocellulosic Byproducts

Abstract

According to the National Company of Supplying (CONAB) in 2017 alone, the national production of acai pulp reached 219 855 t, equating to 180 million dollar (USD). Almost 85% of the weight of fruit is constituted by residual biomass, even though researches have highlighted important applications for this biomass, most of it is discarded as organic waste. Thus, it is relevant to envisage in-depth studies about how to use these residues, particularly regarding the environmental impact of its target destination. Nanocrystalline cellulose (CNC) and lignin are organic derivatives obtained through the physical-chemical treatment of lignocellulosic biomass. Both are abundant and currently considered as biopolymers because of their structural characteristics and their diverse applications in food and the medical field. This work presents the mass yields achieved and the physical-chemical characteristics of the lignocellulosic derivatives extracted from the fiber of the acai berry. A statistical design was used to define the influence of process variables as temperature, reaction time and fiber size on the yield of these byproducts. A maximum yield close to 64% of type I CNC, with 45% of crystallinity degree was achieved at the minimum condition of temperature and fiber size. Additionally, through rheological analysis, it was possible to predict the nanocrystal aspect ratios, ranging from 71 to 125. The extracted lignin was rich in methoxy groups, p-coumaryl alcohol and p-coumaric acid, and its structural unit's low state of aggregation can be an indication of low molecular weight, which envisions an appropriate use for this lignin to produce commodity chemicals.