Lactic acid is a product that finds several applications in food, cosmetic, pharmaceutical, and chemical industries. The main objective of this work is to evaluate potential use of the oil palm (Elaeis guineensis) sap as a substrate by Lactobacillus casei. The effects of pH control and nutrient supplement of oil palm sap on fermentation performance were investigated. In this report, when oil palm sap was used as a carbon source for L. casei, pH control did not significantly affect lactic acid production. The addition of de Man, Rogosa, and Sharpe medium improved the biomass and the product yield for which the lactic acid production in static flask at 37 C and pH 5.5 using 20 g L À1 of total sugar was improved to 0.55 g L À1 h À1 . Oil palm sap could serve as a good potential source of raw materials for efficient production of lactic acid by L. casei. When lactic acid was separated from the fermentation broth with Dowex ™ 66 resin by water as eluant, the desorption yield was 75.16%.

Lactic acid is a product that finds several applications in food, cosmetic, pharmaceutical and chemical industries. The main objective of this work is to evaluate potential use of the sap from palmyra (Borassus flabellifer Linn.) and oil palm (Elaeis guineensis) as substrate for lactic acid production by Lactobacillus casei TISTR 1500. The effects of acid hydrolysis, pH control and nutrient supplement of palmyra sap and oil palm sap on fermentation performance were investigated. It was found that lactic acid fermentation using palmyra sap was not significantly affected by either acid hydrolysis or pH control. The addition of MRS increased biomass and product yield. The final lactic acid concentration, dry cell weight and productivity were increased by increasing the total sugars of palmyra sap concentrations up to 134.0 g L -1 . The kinetic parameters for the palmyra sap at 134.0 g L -1total sugars were calculated to be of: specific growth rate (µ) 0.05 h -1 , the maximum productivity (RM) 2.02 g lactic acid L -1 h -1 , cellular yield coefficient (YX/S) 0.20 g cell g -1 sugar, and lactic acid yield (YP/S) 0.78 g g -1 . When oil palm sap was used as carbon source for L. casei TISTR 1500, pH control did not significantly affect lactic acid production. The addition of MRS medium into oil palm sap improved the biomass and the product yield for which the lactic acid production in static flask at 37ºC and pH 5.5 using 20 g L -1 of total sugars was improved to be of 0.55 g L -1 h -1 . Oil palm sap could be served as a good potential source of raw materials for efficient production of lactic acid by L. casei TISTR 1500.

This study was aimed to investigate the optimal condition of ethanol production that has 2 major stages: acid hydrolysis and fermentation processes. These processes came from low quality sweet potato (LQSP) which was destroyed by the sweet potato weevil. The main compositions of LQSP were starch and fiber which consist of 55.25 and 10.29 %, respectively. In this case, the starch can be hydrolyzed to reduce the sugar, followed by the fermentation of the reduced sugar to ethanol. For this experiment, the effecting factors on acid hydrolysis of LQSP and the ethanol fermentation condition were optimized by S. cerevisiae using Response Surface Methodology (RSM) with Box-Behnken design in order to maximize ethanol yield. It was found that the maximum reducing sugar concentration of 390.99 ± 5.35 g/L was obtained from the hydrolysis condition with 1 % (v/v) of sulfuric acid and 25 % (w/v) of LQSP. Accordingly, the effects of ammonium sulphate content (0.05 - 0.15 %), pH (4.5 - 5.5) and inoculum content (5 - 10 %) on ethanol production was determined by RSM using Box-Behnken experiment design with a total 17 sets of all trials. The results were found that the maximum experimental ethanol productivity of 5.98 g/L was obtained from the condition at 0.05 % of ammonium sulphate, pH 5.5 and 5.0 % of inoculum size to 90 mL LQSP based medium and incubated at 30 °C for 48 h. In addition, the scale-up of ethanol production was studied in 9 L fermenter which provided the maximum ethanol yield of 5.04 g/L. Therefore, it can be concluded that LQSP had a potential as a substrate for ethanol production.

The objectives of this research are to optimize extraction condition for total phenolic compounds from 'Tubtim Siam' pummelo peel using ultrasonic assisted extraction and to determine antioxidant activities of the crude extracts. Variables used to study the optimal extraction conditions of total phenolic compounds include concentration of ethanol (10-50 %v/v), extraction time (15-45 min), and ratio of dried pummelo peel: ethanol solution (1:1, 1:2, 1:3). Furthermore, the optimal were determined using a response surface methodology (RSM) by Box Behnken design. The results showed that these three factors affected the yield of extracted total phenolic. Moreover, the statistical analysis provided indications that the data obtained from the experiment should be fitted to polynomial equation because of its high coefficient of determination with R-square = 0.9294. The highest yields of total phenolic compounds were obtained when the samples were dissolved in ethanol at 35%v/v, the extraction time was set at 30 min and the ratio of solid/ethanol was 1:2. Under these optimal conditions, the highest total phenolic compounds yield were 13.67 ± 0.52 mgGAE/gDW from experimental values and 13.66 mgGAE/gDW from predicted values and the scavenging activity of percentage of inhibition by DPPH assay was 32.58 %.