The Influence of Cu\u3csub\u3e3\u3c/sub\u3e(BTC)\u3csub\u3e2\u3c/sub\u3e metal organic framework on the permeability and perm-selectivity of PLLA-MOF mixed matrix membranes

Poly(l-lactic acid) (PLLA) - 20% (w/w) and Cu3(BTC)2 metal organic framework (MOF) based mixed matrix membranes (MMMs) were fabricated by a vertical corotating twin screw microcompounder followed by an injection molding process. Water vapor, CO2, O2, and selected aroma mass transfer properties of PLLA and PLLA MMMs were evaluated. The CO2/O2 perm-selectivity of PLLA (αCO2/O2) MMMs increased from 7.6 to 10.3 with the incorporation of 20% Cu3(BTC)2 MOF. Gravimetric permeability studies of trans-2-hexenal performed at 23°C and 50% RH indicated that permeability coefficient of PLLA MMMs increased by around 60% as compared to regular PLLA film. However, no changes in mass transfer rates were observed for acetaldehyde. Furthermore, the thermal processing parameters as well as the presence of MOF did not show any significant effect on the molecular weight of the PLLA matrix nor on the crystalline structure of the Cu3(BTC)2 MOF, which was confirmed by both gel permeation chromatography and X-ray diffraction studies

Processing of coconut sap into sugar syrup using rotary evaporation, microwave and open-heat evaporation techniques

Background: Coconut sugar has a caramel color with a taste like brown sugar. It is commonly used as natural sweetener. However, coconut sugar has been produced from coconut sap using a traditional method that involves heating the sap at high temperature (>100 °C) in an open pan for a long period (3–5 h). This conventional method results in an over-cooked sugar, which leads to quality deterioration in terms of both its physical and chemical properties. The current study aimed to investigate the processing of coconut sap into sugar syrup using alternative processing techniques such as rotary vacuum evaporation (RE) and microwave evaporation (ME), comparing them with open-heat evaporation (OHE) technique. Results: Coconut sugar syrup produced by rotary evaporation at 60 °C and 250 mbar vacuum (RE-60) required the shortest production time (12.2 min) and the lowest processing temperature (54.8 °C) when compared with ME (13 min and 103.2 °C) and OHE (46.8 min and 101.6 °C). It also had a light brownish color with a higher L* value (35.17) than the ME (29.84) and OHE (23.84) methods. It was found to contain higher amounts of monosaccharides (fructose and glucose) and lower amounts of disaccharides (sucrose). Furthermore, the amount of energy required for RE-60 (0.35 kWh) was much less than for OHE (0.83 kWh). Conclusion: This study provided an alternative processing method for the sugar processing industry to produce coconut sugar using the rotary evaporation method at 60 °C under 250 mbar vacuum with better physicochemical qualities, shorter processing time, and minimum input energy

Factors affecting browning and crystallisation of palm syrup and palm sugar cake

Doctor of Philosophy (Food Technology), 201

Changes in properties of palm sugar syrup produced by an open pan and a vacuum evaporator during storage

International audienceThe aim of this study was to monitor the changes in the properties of palm sugar syrup produced by an open pan and a vacuum evaporator at 70°C and 80°C during storage under 4°C and room temperature (30°C) for 12 months at monthly intervals. During storage, Maillard reaction took place in samples stored under 4°C lower than those stored under 30°C. This was shown by lower a* values, intermediate browning products (IBP), browning intensity (BI) and HMF content, and higher L* values, fructose, glucose and free amino group contents during storage for 12 months. HMF, a possible mutagen formed by nonenzymatic browning during the heating and storage of sugar based products, seems of particular interest and concern. Only the sample produced by an open pan and stored under 30°C contained HMF content (50.58 mg/kg) higher than the permitted maximum limit (40 mg/kg as recommended by the Codex Alimentarious). However, other samples still contained HMF in agreement with this standard. In addition, the microbiological quality and total soluble solids of all samples complied with Thai legislation standards for palm sugar syrup during 12 months of storage

Characterization of palm sap harvested in Songkhla province, Southern Thailand

International audienceThe purpose of this study was to characterise the quality of palm sap after harvested in Songkhla province, southern Thailand. Ten palm sap samples were analyzed. The results showed differed in physical and chemical quality among samples (P<0.05). The results showed range of L*, a* and b* values between 61.49 to 87.53, 1.46 to 3.52 and 12.41 to 19.31, respectively. The turbidity was ranged from 39.56% to 79.95%. The pH value was varied from 4.19 to 5.23, while total acidity was ranged from 0.27% to 0.93%. The total soluble solids ranged from 10.80 to 17.40OBrix. Total and reducing sugars were varied in a range of 10.36% to 16.94% and 0.88% to 3.56%, respectively. The sucrose, glucose and fructose contents were found vary in a range from 9.29% to 17.44%, 0.50% to 1.85% and 0.50% to 1.81%, respectively. Protein content varied from 0.31-0.39 mg/g. Ethanol was also found in all samples that indicating the fermentation. All results indicated a large variation quality of palm sap although they harvested in the same production area in Songkhla province. The different quality of palm sap was mainly due to the fermentation of sugars by the activity of microorganisms during palm sap collecting time

Effect of processing method on vitamin profile, antioxidant properties and total phenolic content of coconut (Cocos nucifera L.) sugar syrup

Coconut (Cocos nucifera L.) sugar is a more nutritious alternative sugar source as compared to sugar palm (Borassus flabellifer) and sugarcane (Saccharum officinarum L.). This work was aimed to investigate the browning index (BI), vitamin profile and antioxidant properties of coconut sap sugar syrups, which were produced by different processing methods: rotary evaporation (RE), microwave evaporation (ME) and open-heat evaporation (OHE). The results obtained showed that coconut sugar syrup produced by RE-60 contained high antioxidant activities [DPPH (36.71%) and ABTS (34.84%), TPC (299.87 mg per 100 g sample) and FRAP (3.74 mm)]. These values were slightly lower than those of ME and OHE. Coconut sugar syrup (RE-60) also contained higher amounts of vitamin C (1587.27 mg L−1), vitamin B1 (97.44 mg L−1) and vitamin B3 (19.84 mg L−1) compared with those of ME and OHE coconut sugar syrups. RE-60 was the best method to produce coconut sugar syrup in a shorter time with lower browning index and higher vitamin contents