Starch from the Sago (Metroxylon sagu) Palm TreeProperties, Prospects, and Challenges as a New Industrial Source for Food and Other Uses

Recovery of glucose from residual starch of sago hampas for bioethanol production

Lower concentration of glucose was often obtained from enzymatic hydrolysis process of agricultural residue due to complexity of the biomass structure and properties. High substrate load feed into the hydrolysis system might solve this problem but has several other drawbacks such as low rate of reaction. In the present study, we have attempted to enhance glucose recovery from agricultural waste, namely, "sago hampas," through three cycles of enzymatic hydrolysis process. The substrate load at 7% (w/v) was seen to be suitable for the hydrolysis process with respect to the gelatinization reaction as well as sufficient mixture of the suspension for saccharification process. However, this study was focused on hydrolyzing starch of sago hampas, and thus to enhance concentration of glucose from 7% substrate load would be impossible. Thus, an alternative method termed as cycles I, II, and III which involved reusing the hydrolysate for subsequent enzymatic hydrolysis process was introduced. Greater improvement of glucose concentration (138.45 g/L) and better conversion yield (52.72%) were achieved with the completion of three cycles of hydrolysis. In comparison, cycle I and cycle II had glucose concentration of 27.79 g/L and 73.00 g/L, respectively. The glucose obtained was subsequently tested as substrate for bioethanol production using commercial baker's yeast. The fermentation process produced 40.30 g/L of ethanol after 16 h, which was equivalent to 93.29% of theoretical yield based on total glucose existing in fermentation media.

Lactic acid production by Enteroccocus faecium in liquefied sago starch

Enterococcus faecium No. 78 (PNCM-BIOTECH 10375) isolated from puto, a type of fermented rice in the Philippines was used to produce lactic acid in repeated batch fermentation mode. Enzymatically liquefied sago starch was used as the sole carbon source, since sago (Metroxylon spp) is a sustainable crop for industrial exploitation. Liquefied sago starch was inoculated with E. faecium to perform the saccharification and fermentation processes simultaneously. Results demonstrated that E. faecium was reused for 11 fermentation cycles with an average lactic acid yield of 36.3 ± 4.71 g/l. The lactic acid production was superior to that of simple batch mode and continuous fermentation in terms of lactic acid concentration. An un-dissociated lactic acid concentration of 1.15 mM affected the productivity of the cells. Work is in progress to maintain and increase the usability of the cells over higher fermentation cycles.

Cadmium sorption characteristics of phosphorylated sago starch-extraction residue

The residue produced by the extraction of sago starch is usually discarded as a waste material. In this study, we phosphorylated the sago starch-extraction residue with phosphoryl chloride and used the phosphorylated residue to remove cadmium from wastewater. The phosphoric ester functionality in the phosphorylated residue was evaluated by means of infrared microspectrometry and solid-state NMR. The dependence of the cadmium sorption behavior on pH, contact time, and electrolyte concentration and the maximum sorption capacity of the phosphorylated residue were also studied. The cadmium sorption varied with pH and electrolyte concentration, and the maximum sorption capacity was 25.2 mg g(-1), which is almost half the capacity of commercially available weakly acidic cation exchange resins. The phosphorylated residue could be reused several times, although cadmium sorption gradually decreased as the number of sorption-desorption cycles increased. The phosphorylated residue sorbed cadmium rapidly, which is expected to be favorable for the continuous operation in a column.

Fermentation of Metroxylon sagu resistant starch type III by Lactobacillus sp. and Bifidobacterium bifidum

The in vitro fermentability of sago (Metroxylon sagu) resistant starch type III (RS(3)) by selected probiotic bacteria was investigated. Sago RS(3) with 12% RS content was prepared by enzymatic debranching of native sago starch with pullulanase enzyme, followed by autoclaving, cooling, and annealing. The fermentation of sago RS(3) by L. acidophilus FTCC 0291, L. bulgaricus FTCC 0411, L. casei FTCC 0442, and B. bifidum BB12 was investigated by observing the bacterial growth, carbohydrate consumption profiles, pH changes, and total short chain fatty acids (SCFA) produced in the fermentation media. Comparisons were made with commercial fructo-oligosaccharide (FOS), Hi-maize 1043, and Hi-maize 240. Submerged fermentations were conducted in 30 mL glass vials for 24 h at 37 degrees C in an oven without shaking. The results indicated that fermentation of sago RS(3) significantly (P < 0.05) yielded the highest count of Lactobacillus sp. accompanied by the largest reduction in pH of the medium. Sago RS(3) was significantly the most consumed substrate compared to FOS and Hi-maizes.