Production of Carbohydrates from Cardoon Pre-Treated by Acid-Catalyzed Steam Explosion and Enzymatic Hydrolysis

Abstract

Cardoon (Cynara cardunculus) is a promising crop from which to obtain oilseeds and lignocellulosic biomass. Acid-catalyzed steam explosion is a thermochemical process that can efficiently pre-treat lignocellulosic biomass. The drawback is the production of a high number of carbohydrate degradation products in the liquid fraction that could inhibit microbial growth. In this work, the lignocellulosic biomass of cardoon, gathered from a dedicated field, were used as the raw material for the production of fermentable monosaccharides by employing acid-catalyzed steam explosion. The raw material was pre-soaked with a dilute 1% (w/w) sulfuric acid solution and then subjected to steam explosion under three different severity conditions. The recovered slurry was separated into solid and liquid fractions, which were individually characterized to determine total carbohydrate and inhibitor concentrations. The slurry and the washed solid fraction underwent enzymatic hydrolysis to release glucose and pentose monosaccharides. By conducting the pre-treatment at 175 °C for 35 min and hydrolyzing the obtained slurry, a yield of 33.17 g of monosaccharides/100 g of cardoon was achieved. At the same conditions, 4.39 g of inhibitors/100 g of cardoon were produced.

Acid-Assisted Organosolv Pre-Treatment and Enzymatic Hydrolysis of Cynara cardunculus L. for Glucose Production

“…OY increases as a result of higher CD and CR, which depend on the pre-treatment conditions. Harsh conditions allow for an enhanced CD but at the same time reduce the CR; conversely, mild conditions avoid cellulose degradation, decreasing enzymatic hydrolysis efficiency [18,31]. An optimization plot was then generated in order to find the optimal pre-treatment conditions for maximizing the OY response (Figure 4).…”

“…Compared to other processes for the production of glucose from cardoon through enzymatic hydrolysis, the combination of this pre-treatment with cellulolytic enzymes led to higher total glucose production. Ballesteros et al [31] obtained 26.6 g of glucose per 100 g of cardoon using dilute sulfuric acid pre-treatment, while Bertini et al [18] pre-treated cardoon by acid-catalyzed steam explosion and recovered about 21 g of glucose per 100 g RM.…”

“…Its properties and ability to grow in marginal lands suggest that it could be useful for biorefinery purposes [16]. Previous studies used cardoon as a feedstock for the production of monosaccharides and biofuels after a physico-chemical pre-treatment, obtaining high process yields [17,18]. On the contrary, very few studies used cardoon as a feedstock in OV processes, and none of these used an acidified GVL/water mixture coupled with microwave heating [19,20].…”

Bioactive Compounds from Cardoon as Health Promoters in Metabolic Disorders

“…The contents of their vegetal parts range from 4.6 to 55.2 g/100 g d.w. Stems were revealed to have higher amounts (Table 3) [10,35,45,58,60,62,63].…”

“…Cellulose is probably the most abundant and valuable component of lignocellulosic biomass; it is a long-chain polymer, described as the most structural component in plant cells and tissues [64,65]. Its content in cardoon vegetal parts varies between 10.33% and 51.7%, with its greatest content being found in the stems [10,35,45,58,60,62,63]. Cellulose is a versatile polymer, being utilized by several sectors, such as veterinary foods, wood and paper, fiber and clothes, and cosmetics and pharmaceuticals as an excipient [65].…”