Weijun Chen

Chemical composition changes of post-harvest coconut inflorescence sap during natural fermentation

Coconut inflorescence sap (CIS) is sweet, oyster-white and translucent and was reported to be highly nutritive and a good digestive agent. The chemical composition changes including total sugar, reducing sugar, ethanol, total acidity, volatile acid, amino acid, vitamin C and total phenolic contents of postharvest coconut inflorescence sap (PCIS) were investigated during a 12-day natural fermentation, and the variety and content of phenolic compounds of fresh coconut inflorescence sap (FCIS) and natural fermented coconut inflorescence sap (NCIS) were also studied by an high performance liquid chromatography (HPLC) system. Total acid, volatile acid and total phenolic contents increased during natural fermentation, while total sugar contents decreased during natural fermentation. The amino acid content declined steadily after harvesting until 3 days, but then remained almost constant. Vitamin C content decreased on day 1, slowly rose to 20.7 mg/L on day 3, and then decreased obviously. Five kinds of phenolic compounds were detected by HPLC. These compounds all increased in NCIS compared with FCIS; both NCIS and FCIS also contained other kinds of phenolic compounds.

Electrochemical determination of indole butyric acid by differential pulse voltammetry on hanging mercury drops electrode

A voltammetric method for the determination of trace amounts of indole butyric acid was developed. DP voltammetry of indole butyric acid exhibits tensammetric peak at the adsorption and desorption potential of indole butyric acid. In the potential range where adsorption occurs, the base current is depressed. The determination method is based on the adsorption of indole butyric acid on a hanging mercury drop electrode and desorption of indole butyric acid at negative tensammetric peak. The system showed no positive tensammetric peak on hanging mercury drop electrode under the experimental conditions. The tensammetric peak potential of indole butyric acid was between −500 and −600xa0mV (versus Ag/AgCl), depending on pH, accumulation potential, accumulation time, sweep rate, pulse amplitude and so on. Variation of the sweep rate between 40 and 140xa0mV/s caused a linear increase in the tensammetric peak height. The peak current was proportional to the concentration of IBA over the range 40–320xa0μg/L under optimum experimental conditions (pHu2009=u20093.5, accumulation potential of −1.2xa0V and accumulation time of 120xa0s).

The inhibiting activity of areca inflorescence extracts on human low density lipoprotein oxidation induced by cupric ion

The oxidative modification of human low density lipoprotein (LDL) plays a significant role in atherosclerosis. In this study, the inhibiting activity of areca inflorescence extracts (AIEs) on LDL oxidation was investigated by an in vitro study with Trolox as the standard antioxidant. The kinetics of LDL oxidation, thiobarbituric acid reactive substances assay, ferric-reducing antioxidant power assay and copper chelation assay were also evaluated to assess the antioxidant activities of AIEs, and the results revealed that AIEs could delay the lag time and inhibit the formation of malondialdehyde in the process of LDL peroxidation induced by Cu2+. The boiled water extract displayed the highest antioxidant activity compared with the ambient water extract and ethanol extract. The total phenolic contents and phenolic components of AIEs were also measured by high performance liquid chromatography method. Epicatechin, gallic acid and coumalic acid were the primary phenolic acids in AIEs.

Chemical composition of Chinese palm fruit and chemical properties of the oil extracts

The proximate composition, mineral concentration of fleshy mesocarp, palm meat (PM) and palm kernel (PK) of oil palm fruit ( Elaeis guineensis S.L.Dura ) produced in Hainan, China were investigated. The fatty acid composition, chemical properties and minor constituents of palm oil (PO) and palm kernel oil (PKO) were also studied. The crude fat of PM and PK were 68.09±3.57% and 49.36±2.61%, respectively. The PM and PK were found to be good sources of minerals. The acid value (AV) and free fatty acid (FFA) of PO extracted from fresh PM were much higher. If the fresh PM were heated at 100oC for 30 min, the AV and % FFA could be reduced to 4.62±0.04 mgKOH/g and 2.72±0.002%, respectively. The major fatty acid of PO was palmitic acid 39.93±1.66% and that of PKO was lauric acid 48.01±0.69%. Tocopherol isomer (α-, (β+γ)- and δ-) contents in PO were 68.8±1.84, 22.8±0.54 and 11.8±0.12 mg/kg, respectively. The β-carotene content in PO was 901.5±11.95 mg/kg. The content of sterols in PO and PKO were 880.0±5.23 and 858.0±4.37 mg/kg, respectively. PO and PKO exhibited good chemical properties and could be used as edible oils and for industrial applications. There are almost no data about Chinese palm fruit now and this study systematically researched on it, which can provide useful information for Chinese oil palm industry. Key words: Chemical composition, palm fruit, palm oil, palm kernel oil, chemical properties.