EFFECTS OF ALKALIZED COCOA POWDER AND SOY LECITHIN ON PHYSICAL CHARACTERISTICS OF CHOCOLATE BEVERAGE POWDERS

Chocolate beverage powders (CBPs) were produced from alkalized cocoa powder (ACP) at 10–30% and soy lecithin (SL) at 0–4%. Response surface methodology (RSM) was used to determine the optimum level of ACP and SL on sedimentation, wettability, bulk density, despersibility, moisture content and flavor acceptability. SL was effective on wettability, and it also showed an optimum level for sedimentation and bulk density, while ACP was found to be significant for all physical properties. For sensory evaluation, flavor was acceptable at 20% ACP level soy taste was detected by panelists in CBPs with high SL and low ACP contents. It was found that as the ACP content was increased the soy taste of CBPs decreased. For overall physical characteristics, the optimum levels of 20% of ACP and 2–4% of SL were selected.     

EVIDENCE OF CROSS-CONTAMINATION OF AEROMONAS HYDROPHILA BY FINGERPRINTING: SIGNIFICANCE FOR FOOD SAFETY

The prevalence of Aeromonas hydrophila in a local wet market was studied and fingerprinting was used to prove the cross‐contamination. This study describes the use of antibiotic‐resistant plasmid profiles and random amplified polymorphic DNA (RAPD) assay to characterize strains of A. hydrophila. Almost all strains had multiple antibiotic resistances and carried small plasmid(s) of 1.4–6.0 MDa that enabled the A. hydrophila to be grouped into eight plasmid patterns. The RAPD‐polymerase chain reaction profiles observed after electrophoretic separation of the amplified products using primer GEN15007, which enable the A. hydrophila strains to be grouped into three clusters, demonstrate that the A. hydrophila strains were genetically heterogeneous. These results suggest that RAPD assay could be a valuable tool for epidemiological studies. In addition, antibiotic‐resistant and plasmid profiling can also be used as adjunct tools in this study.     

EFFECT OF GLUCOSE SYRUP SOLID, SUCROSE, HYDROGENATED PALM OIL AND SOY-LECITHIN ON SENSORY ACCEPTABILITY OF DURIAN LEATHER

A two-stage optimization of ingredients in durian leather formulations was conducted using Response Surface Methodology (RSM). In stage 1, the independent variables were glucose syrup solids (GSS) and sucrose, and in stage 2, the variables were hydrogenated palm oil (HPO) and soy-lecithin (SL). Based on the responses to sensory acceptability attributes including taste, aroma, texture, appearance and overall acceptability, the most acceptable formulation was a combination of 10% GSS, 5% sucrose, 2.67% HPO and 0.452% SL. Chemical analysis also showed that during processing nutrient composition was relatively unchanged.     

EFFECTS OF SOY PROTEIN ISOLATES ON QUALITY OF CHOCOLATES DURING STORAGE

The effect of soy protein isolate (SPI) on oxidation rate, changes in color and hardness, and microbiological aspect of chocolates during storage were studied. The Peroxide Value (PV) of the control and 5% showed SPI were highest in week 3 and decreased at the following week, while 10% SPI showed the lowest PV in week 10 as compared to the others. The Anisidine Value (AV) of all chocolates showed an increasing pattern during 10 weeks of storage. The Total Oxidation Value (TV) of all chocolates was found to be highest at week 3 and lowest at week 10 when 10% SPI was used. During storage, all chocolates slightly increased in hardness and turned darker in color. The Total Plate Count (TPC) of the control and SPI chocolates was less than 1,000 colonies/g.     

MONITORING OF TRANSESTERIFICATION OF PALM OIL BY DIFFERENTIAL SCANNING CALORIMETRY

Chemical transesterification was conducted to obtain triacylglycerol ( TG) containing maximum concentrations of trisaturated and triunsaturated TG in palm oil. Catalyst (sodium methoxide) concentration of 0.1–0.5%, reaction temperature of 50–92C and reaction time of 30–480 min were applied in 20 treatments. Concentrations of trisaturated and triunsaturated TG, as well as melting points and iodine values were monitored by differential scanning calorimetric (DSC) techniques. The results showed that maximum trisaturated and triunsaturated TG achieved for refined-bleached-deodorized (RBD) palm oil were 17.10 and 7.50%, respectively, using 0.42% catalyst, at 58C in 389 min. These amounts were higher compared to control (untransesterified) RBD palm oil i.e 7.45 and 4.92%, respectively. The melting points of the products were higher compared to the control, while the iodine values were not significantly changed in all of the treatments.     

OPTIMIZATION OF CHEMICAL TRANSESTERIFICATION OF PALM OIL USING RESPONSE SURFACE METHODOLOGY

The effect of catalyst concentration (0.1–0.5% methoxide powder), temperature (50–92C), and time (30–480 min) of chemical transesterification was studied to determine the optimum condition for maximizing concentration of triunsaturated and trisaturated triacylglycerols (TG) in palm oil. TG compositions of the oil were analysed using high-performance liquid chromatography. The optimum condition of the process was determined using statistical response surface methodology. The results showed that the triunsaturated and trisaturated TG responses followed a second order form of the treatments with R²= 0.83 and 0.85, respectively. The triunsaturated TG reached a maximum concentration by using 0.36% catalyst at 78C and 360 min reaction time, whereas the trisaturated TG with 0.36% catalyst at 81C and 325 min reaction time. Considering the two responses, it was concluded that the overall optimum condition could be achieved at 0.36% of catalyst at 78–81C and 325–360 min reaction time. Such conditions increased trisaturated TG in palm oil by 2.34 times and triunsaturated TG by 1.54 times.     

EFFECT OF DIFFERENT DRYERS AND DRYING CONDITIONS ON ACCEPTABILITY AND PHYSICO-CHEMICAL CHARACTERISTICS OF DURIAN LEATHER

Optimization study on drying condition ofdurian leather was carried out using Response Surface Methodology (RSM). The optimization was conducted for two different dryers, oven dryer and forced-air cabinet dryer, with temperature and time of drying as independent variables. It was shown that both variables significantly affected most of the sensory properties. For both dryers, the optimum points for 5 sensory attributes evaluated including taste, aroma, texture, appearance and overall acceptability, were at temperatures ranged from 47–55 C for 10–14 h. Based on the overall acceptability, the optimum condition for oven-dried leather was achieved at temperature 50C for 12.6 h, while for cabinet-dried leather at 52.5C for 10 h. Results showed that panelist preferred product dried with low temperature-long time compared with high temperature-short time. Except for Hunter color b value of cabinet-dried product, results also indicated that drying condition was significantly influencing the physico-chemical properties such as moisture, A_w, nonenzymatic browning, texture, vitamin C and color of durian leather.