Production of high yield sugars from Kappaphycus alvarezii using combined methods of chemical and enzymatic hydrolysis

Abstract

The characteristics and functional properties of polysaccharides extracted from Malaysia's seaweeds have not been fully established to date. Hence, this study was carried out to produce high yield fermentable sugars from Kappaphycus alvarezii for the potential production of biotechnology products such as bioflavours. In order to achieve this objective, the effectiveness of hydrolysis process was studied by using chemical treatments, followed by enzymatic treatments. K. alvarezii were hydrolysed in different heating times and temperatures followed by different types of acids and their concentrations. The optimal conditions for chemical hydrolysis were achieved at 8.0 g/100 mL of dried powder K. alvarezii in 0.2 M H2SO4 and HCl at 110 °C for 90 min which produced 34.275 ± 0.976 g/L and 35.872 ± 3.610 g/L, respectively with 42.8% and 44.8% of yield of sugar production. However, there are no significant different between H2SO4 and HCl. Thus, H2SO4 was chose as a catalyst for chemical hydrolysis. As for the combination of chemical and enzymatic hydrolysis, several pH of hydrolysates and incubation temperature were studied. The optimum condition for Celluclast activity was at pH 5.5 and 50 °C incubation temperature which produced the highest reducing sugars with an increment of 15.60 g/L from the chemical hydrolysis alone. The yield of reducing sugars after combining both methods reached 62.35% (49.92 ± 1.163 g/L reducing sugar). From this study, the characterization of these seaweeds can lead to a better understanding of their functional characteristics and promote the exploitation of these natural resources for the production of expensive new biotechnology products.

Comparison of different process strategies for bioethanol production from Eucheuma cottonii: An economic study

“…Based on Table S6, our study shows a better result, with the concentration of sugars at 98.7 g/L, compared with Abd-Rahim et al (2014). The concentration of reducing sugars after combining both methods reached 49.9 g/L when EC (whole biomass) was hydrolyzed with sulfuric acid followed by enzymatic hydrolysis.…”

“…However, j-carrageenan content cannot be easily hydrolyzed by the enzyme because of their ability to bind with water effectively, thus forming weak water gels which are very stable against enzymatic degradation. Recently, several studies reported bioethanol production from Kappaphycus alvarezii (E. cottonii) using sulfuric acid as the catalyst (Abd-Rahim et al, 2014;Hargreaves et al, 2013). Nevertheless, these methods have major drawbacks in product separation, reactor and equipment corrosion, and waste effluent treatment (Guo et al, 2012).…”

Seaweed Bioethanol Production: A Process Selection Review on Hydrolysis and Fermentation

“…Generally, seaweeds contain large amounts of complex sulphated carbohydrates (polysaccharides) that are often extracted for use mainly in the hydrocolloid industry [8]. Each seaweed group uniquely consists of different types of complex polysaccharides serving as storage and supporting structural tissue such as the cell wall [20].…”

“…Various treatments have been used during hydrolysis of seaweed for bioethanol production. These treatments include dilute acid thermal [20,54,55], dilute alkaline thermal [15,56], enzymatic [50,57,58], thermal [55,59], ball milling [17], hydrothermal (HTT) [17] and ultrasound [60]. These are usually grouped into physical, chemical, thermal and enzymatic treatments.…”

“…Abd-Rahim et al [20], also combined acid and enzymatic hydrolysis. K. alvarezii (8% w/v DM) was first hydrolysed with 0.2 M H 2 SO 4 (110 • C for 90 min) to obtain an initial reducing sugar concentration of 34.3 g/L.…”