Development of bambangan (Mangifera pajang) carbonated drink

Mangifera pajang Kostermans or bambangan is a popular fruit among Sabahan due to its health and economic values. However, the fruit is not fully commercialized since it is usually been used as traditional cuisine by local people. Thus, development of bambangan fruit into carbonated drink was conducted to produce new product concept. The objectives of this study were to conceptualize, formulate, evaluate consumer acceptance, and determine physicochemical properties and nutritional composition of the accepted product. Method used in conceptualising the product was based on questionnaire. The consumer acceptance was evaluated based on descriptive and affective tests with four product formulations tested. The physicochemical properties on carbon dioxide volume, colour, pH, total acidity, total soluble solid (TSS) and viscosity were highlighted, meanwhile nutritional composition on fat, protein, carbohydrates and energy content were determined. About 77% respondents gave positive feedback, and 69% respondents decided this product is within their budget. The formulation of 5% bambangan pulp, 70% water, 25% sugar and 0.2% citric acid was highly accepted in descriptive and affective tests with 4.4 and 6.39 mean scores, respectively. The physicochemical properties and nutritional composition of the acceptance product were in optimum value except for colour, total acidity and TSS. Overall, this study showed that the product has high potential to be commercialized as new product concept, and heritage of indigenous people can be preserved when this fruit is known regionally

Combine strategy of treated activated charcoal and cell surface protein curli induction for enhanced performance in escherichia coli immobilization

Immobilization of Escherichia coli (E. coli) on commercial activated charcoal was enhanced by mild chemical treatment coupled with curli production from E. coli. The chemical used to treat the activated charcoal were sodium hydroxide, hydrochloric acid, ammonium hydroxide, and acetic acid while nickel (II) chloride was used to promote the production of curli. Characteristics of the activated charcoal before and after chemical treatments were analyzed including its surface properties, pore size, and crystalline structure. The immobilization of E. coli was enhanced greatly after sodium hydroxide treatment which gave rise to more than 120 % cell immobilized compared to the untreated activated charcoal which was mainly attributed to the larger size of macropore, surface area, and pore volume. Curli were produced by the induction of nickel (II) chloride and further enhanced the cell immobilization by at least 50 %. Overall, the combine strategy enhanced cell immobilization by more than 160 %. The resulting biocatalyst from the enhanced cell immobilization managed to be reused up to 10 cycles for the enzyme cyclodextrin glucanotransferase expression while retaining up to 60 % of the enzyme's initial activity

Effect of Tryptone Concentration on Cyclodextrin Glucanotranferase (CGTase) Excretion and Cell Lysis of Immobilized Recombinant Escherichia coli

The recombinant enzyme excretion into the culture medium provides significant advantages over cytoplasmic expression. Nevertheless, the problems encountered during the excretion of recombinant enzyme are the plasmid instability and occurrence of cell lysis. Various attempts have been made to improve the recombinant enzyme excretion and plasmid stability with the low occurrence of cell lysis. The approaches include the modification of the nitrogen sources in the medium such as tryptone, the use of cell immobilization system and lowering the induction temperature. In the present study, the effects of different tryptone concentrations (1, 5, 10, 20 and 30 g/L) as nitrogen source in super optimal broth (SOB) medium on CGTase excretion and plasmid stability as well as cell lysis of the immobilized cell were studied. The recombinant E. coli was immobilized on polyvinylidene fluoride polymer (PVDF) hollow fiber membrane. The immobilized cells were expressed using 0.011 mM IPTG at 25°C, 200 rpm of agitation rate and pH 8.8 for 24 h of post induction time. The use of low tryptone concentration (5 g/l) produced high CGTase excretion (758.64 U/ml) and increased the plasmid stability (86% increment) with reduction of cell lysis (90% reduction) in comparison with the initial tryptone concentration (20 g/l). Hence, low concentration of tryptone could reduce the cost for CGTase production due to low amount of tryptone used in the fermentation process