Sugar hydrolysis yield

They are found in a great variety of plants and are strong fish poisons. On hydrolysis they yield a variety of sugars, frequently several molecules to each aglucone. Glucose, galactose, arabinose are the more common pentoses, methylpentoses and glucuronic acid are also obtained. 

The particular wood species we chose for this study is aspen (Populus tremuloides), which is plentiful in Canada and in the northern U.S.A. The chemical composition we found to be glucan 53.4%, xylan 14.9%, total carbohydrate 79.0%, lignin 17.1% and extractives 3.8%. We would expect total fermentable sugars of about 56% in this sample of aspen in anhydro form (Timell has reported about 60% in another sample (15)) which upon hydrolysis would yield about 1,250 lb wood sugars per ton of wood (dry basis), from the stoichiometry. Theoretical conversion of this sugar to ethanol would yield 640 lb or 81.1 gallons of anhydrous... 

V. Gums are the secretory products of plants. On hydrolysis they yield simple sugar like polysaccharides. They are pharmacologically inert substances and mainly employed as suspending and emulsifying agent in various pharmaceutical products. 

Dilute Acid Hydrolysis. Data relative to the acid saccharification of the four substrates at various levels of vibratory ball milling are given in Table III and plotted as rate and yield curves in Figures 7 and 8. Table IV summarizes the half-life and maximum sugar yield values derived from these curves. 

Figure 8. Effect of ball milling on sugar yield—acid hydrolysis...

The relative influence of vibratory milling on the course of enzymatic and dilute acid hydrolysis of four cellulosic substrates was investigated. The four substrates—cotton linters, newsprint, Douglas fir, and red oak— were vacuum-dried and then milled for various time periods ranging up to 240 min. Assays were then made of rate and extent of hydrolysis, maximum yield of reducing sugar, and cellulose crystallinity. 

Vibratory milling also yields substantial increases in the rates of dilute acid hydrolysis of all four substrates nearly nine-fold for cotton linters and roughly five-fold for the three lignocelluloses. Increases in maximum sugar yields under simple batch conditions ranged from 60% to 140% over the yields for the unmilled materials. 

The whole procedure normally takes about 1 hr. The acid is then evaporated, and the dry matter can be analyzed. This method can be applied to cellulose from wood, as a-cellulose or pulp, or to other celluloses (e.g., cotton) as well as to cellulosic materials with higher amounts of other polysaccharides (e.g., holocellulose). The chromatograms of the hydrolysates of a-cellulose from beechwood and of holocellulose from sprucewood (Figure 6) are examples of the application of this method. Compared with sulfuric acid hydrolysis, the total sugar yield from the spruce holocellulose is higher after the hydrolysis with concentrated TFA (Table II). Regarding the individual sugars, it can be seen that the... 

Table IV. Corrected Sugar Yields after Intensive Hydrolysis of Wood and Pulp with Trifluoroacetic Acid ...

The highest overall sugar yield after both pretreatment and enzymatic hydrolysis, 56.1 g/100 g of DM, was also obtained at 190°C, for 5 min with 2% H2S04. 

Steam treatment of an industrial process stream, denoted starch-free wheat fiber, was investigated to improve the formation of monomeric sugars in subsequent enzymatic hydrolysis for further bioconversion into ethanol. The solid fraction in the process stream, derived from a combined starch and ethanol factory, was rich in arabinose (21.1%), xylose (30.1%), and glucose (18.6%), in the form of polysaccharides. Various conditions of steam pretreatment (170-220°C for 5-30 min) were evaluated, and their effect was assessed by enzymatic hydrolysis with 2 g of Celluclast + Ultraflo mixture/ 100 g of starch-free fiber (SFF) slurry at 5% dry matter (DM). The highest overall sugar yield for the combined steam pretreatment and enzymatic hydrolysis, 52 g/100 g of DM of SFF, corresponding to 74% of the theoretical, was achieved with pretreatment at 190°C for 10 min followed by enzymatic hydrolysis. 

Sugar Yields After Pretreatment and Acid Hydrolysis Performed in Microwave Oven Followed by Enzymatic Hydrolysis... 

Table 3 shows the sugar yields obtained after pretreatment and enzymatic hydrolysis of the SFF material used in the present study and the SFF material utilized in a previous study (boldface in Table 3) (4). The sugar yields obtained with acid hydrolysis in a microwave oven followed by enzymatic hydrolysis are also given. Unless otherwise stated, the yields following pretreatment and enzymatic hydrolysis are expressed as g/100 g of dry SFF. Galactose was present at very low amounts in both materials.

Fig. 2. Effect of severity factor (Log [R0]) on total sugar yield after steam pretreatment (SP) and after combined SP and enzymatic hydrolysis (EH).

Fig. 4. Sugar yields as a function of enzymatic hydrolysis time. Comparison of best combination of pretreatment and enzymatic hydrolysis methods using either micro-wave oven (MW) or steam pretreatment (SP).

Acid hydrolysis with 0.2% H2S04 at 160°C for 20 min resulted in 50% of the theoretical sugar yield. This is approximately the same yield as that obtained with direct enzymatic hydrolysis. When the acid hydrolysis was followed by enzymatic hydrolysis, the sugar yield increased to 88% of the theoretical. Analysis of furfural and HMF showed that only 0.2 g/L of furfural was present in the slurry and no HMF was formed. 

Direct enzymatic hydrolysis with the supplementation of Ultraflo to the Celluclast resulted in a significant increase in yield compared with when Celluclast alone was used (Fig. 6). The maximum sugar yield for direct enzymatic hydrolysis, 36.6 g/100 g, corresponding to 52% of the... 

Fig. 6. Total sugar yield as function of time for direct enzymatic hydrolysis with enzyme loadings of 0.5 g of Celluclast + Ultraflo/100 g of SFF slurry, 0.5 g of Celluclast/100 g of SFF, 2 g of Celluclast + Ultraflo/100 g of SFF slurry, and 2 g of Celluclast/100 g of SFF.

Individual and Total Sugar Yields Following Direct Enzymatic Hydrolysis of SFF and Following Combined Steam Pretreatment at 190°C for 10 min and Enzymatic Hydrolysis. 

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