Xylitol can be obtained from lignocellulosic materials containing xylose. However, the fraction of lignocellulose converted through dilute acid hydrolysis contains compounds that inhibit the fermenting micro-organisms. These inhibitors can be removed from the hydrolysate by detoxification method, prior to fermentation. This study describes effectiveness of overliming process to reduce the toxicity of hydrolysates generated from pre-treatment of sago trunk for xylitol production. The overliming pH 9 and 10 was studied and the results showed that pH 9 was showed 20% of sugar loss, which is low compared to pH 10. Candida tropicalis strain was used to evaluate the fermentability of overlimed sago trunk hydrolysate at pH 9 and non-overlimed hydrolysate medium. Meanwhile, Xylitol accumulation and productivity in the overlimed medium was found to be higher than the non-treated medium. The maximum production of xylitol was increased up to 74% and converted within 76 h. The results obtained improved the fermentation process when compared with the nontreated medium.
Fish protein hydrolysate was recovered from tilapia by-product (TB) through enzymatic hydrolysis using alcalase enzyme. Hydrolysis reaction of TB was monitored according to the degree of hydrolysis (DH) by employing O-phtaldialdehyde (OPA) method. Optimization process for obtaining high yield of TB protein hydrolysate was performed using response surface methodology (RSM) by optimizing a combination of four independent variables namely, pH (6.5-8.5), temperature (55-70oC), substrate concentration (10-17.5% w/v), and enzyme concentration (1.5-3.5% w/w) with (DH) as a response. The optimum enzymatic hydrolysis conditions were obtained at pH 7.5, temperature of 60oC, substrate concentration of 15% (w/v) and 2.5% (w/w) of enzyme concentration and yielded about 20.20% of DH after hydrolyzing for 120 min. RSM generated model predicted that 20.42% of DH could be achieved at these conditions and this model was valid based on the DH value obtained from the experimental study (20.31%) which was quite similar with the predicted value. High yield of DH obtained from the optimization process could produce fish protein hydrolysate with good nutritional and functional properties.
Dadih is a favourable dessert in South East Asia due to its appealing sweet taste and jellies
appearance. The sweet taste is from sugar (sucrose) content, and in order to reduce the sucrose,
it was substituted with xylitol. Xylitol can provides intense sweetness with less calories and
lower water activity, which potentially contribute to higher microbial stability thus giving
longer shelf life. The objective of this study was to evaluate the effect of xylitol substituted
on dadih safety and sensory qualities. Dadih was prepared by replacing sucrose with xylitol
composition in the range of 0 – 100% and at two levels of cooking times (15 and 20 minutes).
Safety analysis were performed using total plate count (TPC) and water activity (aw) analysis.
For sensory analysis, seven attributes were evaluated (appearance, colour, hardness, elasticity,
taste, sweetness, and overall acceptability) based on the 9-hedonic scale. From the findings,
dadih samples with total sucrose (0%) were observed to be contaminated faster compared to
total xylitol (100%). Dadih with xylitol is more stable with prolonged shelf life. From sensory
analysis, dadih sample prepared with shorter cooking time (15 minutes) was selected as more
favourable with overall acceptability score between 72 - 85%. More than 70% of the score for
dadih with xylitol substitute was above ‘slightly like’, which indicates a promising future to
produce xylitol substitute dadih. The outcome of this study has shown that xylitol is potentially
to be utilize as sugar substitute for dadih production.