Showing papers in "Asian Journal of Food and Agro-Industry in 2011"

Characteristics and antioxidant activity of palm sugar syrup produced in Songkhla Province, southern Thailand.

Abstract: Palm sugar syrup is obtained by heating fresh palm (Borassus flabellifer, Linn.) sap on a wood fire stove until it becomes a concentrate. The product properties vary extremely across the samples and within an individual local producer. Therefore, the objective of this study was to characterize the quality profile and antioxidant activity of palm sugar syrup produced in Songkhla Province. Twenty palm sugar syrup samples from primary producers in the province were analyzed for their quality and antioxidant activity. The results showed differences among the samples (P<0.05). The results also showed ranges in L*, a* and b* colour values of between 5.34 to 30.14, 21.13 to 36.14 and 8.19 to 56.12, respectively. The transmittance value ranged from 1.00% to 17.01%. The intermediate browning product (IBP) ranged from 0.42 to 1.25 and the browning intensity (BI) ranged from 0.57 to 1.52, respectively. The pH value varied between 4.49 and 5.42, while the total acidity varied from 0.20% to 0.52%. The total soluble solids ranged from 62.97Brix to 72.57Brix. The sucrose content ranged from 59.15% to 84.37%; the glucose and fructose content varied from 4.01% to 24.13% and 4.44% to 23.55%, respectively. The HMF content was found to vary between 20.13 mg/kg and 185.39 mg/kg. Iron content ranged from 3.27 μg/g to 59.43 μg/g and copper content varied from 1.53 μg/g to 3.97 μg/g, respectively. The total phenolic content ranged from 1.35 mg/g to 2.21 mg/g. DPPH radical scavenging activity varied from 13.27 μmol TE/g to 18.49 μmol TE/g. Ferric reducing antioxidant power ranged from 21.33 μmol TE/g to 30.62 μmol TE/g. Reducing power varied from 0.85 to 1.45. Therefore, these data can be used as a guideline to differentiate the quality of palm sugar syrup.

Degradation kinetics and colour of anthocyanins in aqueous extracts of butterfly pea

Abstract: The degradation kinetics and the colour display of anthocyanins in butterfly pea extract under different pH (1-10) and temperature (25, 50, 80 and 95oC) were studied. First order thermal degradation parameters, such as k-values, activation energy (Ea), half-life values (t1/2), D-values, zvalues and Q10-values, as well as the changes in Hunter lightness (L*), chroma (C*) and hue (H o ) were determined. Thermal degradation of anthocyanin in butterfly pea extract at pH 3 corresponds to first order kinetics. The Browning index, percentage polymeric colour, L* and H 0 parameters increased with time according to zero-order kinetics reaction (for L* and H 0 ), while C* decreased with time according to the first-order kinetics. For tinctorial strength, colourant concentration directly affected the L*, H 0 and C* values. The visual colour of the extract was also affected by tinctorial strength. The use of butterfly pea as a source of natural colourants shows potential use in the pH region of around 3.