Study on Dissociation and Chemical Structural Characteristics of Areca Nut Husk

Abstract

From the perspective of full-component utilization of woody fiber biomass resources, areca nut husk is an excellent woody fiber biomass feedstock because of its fast regeneration, significant regeneration ability, sustainability, low cost, and easy availability. In this study, fiber cell morphologies, chemical compositions, lignin structures, and carbohydrate contents of areca nut husks were analyzed and compared with those of rice straw, and the application potentials of these two materials as biomass resources were compared. We found that areca nut husk fibers were shorter and wider than those of rice straw; areca nut husk contained more lignin and less ash, as well as less holocellulose than rice straw; areca nut husk and rice straw lignin were obtained by ball milling and phase separation, and areca nut husk lignin was found to be a typical GHS-type lignin. Herein, the yield of lignocresol was higher than that of milled wood lignin for both raw materials, and the molecular size was more homogeneous. Tricin structural monomers were discovered in the lignin of areca nut husk, similar to those present in other types of herbaceous plants. Structures of areca nut husk MWL (AHMWL) and AHLC were comprehensively characterized by quantitative NMR techniques (that is, 1H NMR, 31P NMR, and 2D NMR). The molecular structure of AHLC was found to be closer to the linear structure with more functional groups exposed on the molecular surface, and the hydroxyl-rich p-cresol grafting structure was successfully introduced into the lignin structure. In addition, the carbohydrate content in the aqueous layer of the phase separation system was close to the carbohydrate content in the raw material, indicating that the phase separation method can precisely separate lignin from carbohydrates. These experimental results indicate that the phase separation method as a method for lignin utilization and structure study has outstanding advantages in lignin structure regulation and yield, and areca nut husk lignin is suitable for application in the same phase separation systems as short-period herbs, such as rice straw and wheat grass, and has the advantages of low ash content and high lignification degree, which will provide guidance for the high-value utilization of areca nut husk in the future.

Bioactive Components of Areca Nut: An Overview of Their Positive Impacts Targeting Different Organs

“…The major constituents of areca nut are polyphenols (10–30%), polysaccharides (18–25%), fibers (10–15%), fatty acids (10–15%), and alkaloids (0.3–0.7%) [ 21 , 22 ]. Areca nut husk is primarily composed of cellulose and contains more lignin, which makes it have higher hardness and produce more mechanical friction on the oral mucosa during chewing, but it can be an excellent wood fiber resource material [ 8 , 23 ]. Apart from that, there are a variety of bioactive substances in areca nut ( Figure 1 ).…”

“…It has to be noted that areca nut is considered to represent a risk due to its association with oral and esophageal cancers [ 7 ]. Firstly, areca nut husk is rich in crude fiber, which makes it hard and rough in texture, thus chewing areca nut would produce long-term mechanical irritation on the oral mucosa, which has been proposed as a pivotal risk factor for oral cancer [ 23 , 191 , 192 ]. Secondly, areca nut extracts and arecoline are found to have cytotoxicity and carcinogenic effects on human oral mucosal fibroblasts and gingival fibroblasts in vitro [ 193 ].…”

Edible Quality Analysis of Different Areca Nuts: Compositions, Texture Characteristics and Flavor Release Behaviors

“…The microstructure of the areca nut fiber was observed using a fluorescence microscope (AE31, MOTIC China Group Co., Xiamen, China) [17]. The moisture content of the areca nut fiber was tested using the direct drying method [18].…”

Active Soil Organic Carbon Pools Decrease with Increased Time since Land-Use Transition from Rice Paddy Cultivation to Areca Nut Plantations under the Long-Term Application of Inorganic Fertilizer

“…The areca nut, a perennial evergreen woody plant of the Palmaceae, is one of the most important commercial crops in the tropics and has substantial economic value [1]. In recent years, areca nut has become the second largest commercial crop in the tropics of China, with an area of approximately 102,500 ha, making it the primary economic source in this region [2]. Over the last decades, many croplands in the tropics of China have been converted into areca nut plantations due to their high economic returns [3].…”

“…Active organic C, however, is highly susceptible to mineralization and decomposition [8]. Although soil reactive C fractions (e.g., soil particulate organic C (POC), light fraction organic C (LFOC), dissolved organic C (DOC), and easily oxidizable organic C (EOC) account for a low proportion of total SOC; they are more sensitive to land-use change and can better reflect soil C pools balance and soil fertility [2]. Previous studies have generally focused on how the conversion of croplands to natural ecosystems leads to an increase in SOC storage [9].…”