Suchila Techawongstien

A novel extraction method for β-carotene and other carotenoids in fruit juices using air-assisted, low-density solvent-based liquid-liquid microextraction and solidified floating organic droplets.

Green extraction using air-assisted, low-density solvent-based liquid-liquid microextraction and solidified floating organic droplets (AA-LDS-LLME-SFOD) prior to spectrophotometry was successfully applied for quantitation of carotenoids in fruit juices. Under optimal conditions, β-carotene could be quantified with a linear response up to a concentration of 60 μg mL(-1). The procedure was performed in a microcentrifuge tube with 40 μL of 1-dodecanol as the extraction solvent and a 1.0 mL juice sample containing 8% NaCl under seven extraction cycles of air pumping by syringe. This method was validated based on linearity (0.2-30 μg mL(-1), R(2) 0.998), limit of detection (0.04 μg mL(-1)) and limit of quantification (0.13 μg mL(-1)). The precision, expressed as the relative standard deviation (RSD) of the calibration curve slope (n=12), for inter-day and intra-day analysis was 4.85% and 7.92%, respectively. Recovery of β-carotene was in the range of 93.6-101.5%. The newly proposed method is simple, rapid and environmentally friendly, particularly as a useful screening test for food analysis.

Enzymatic changes in phenylalanine ammonia-lyase, cinnamic-4-hydroxylase, capsaicin synthase, and peroxidase activities in capsicum under drought stress.

Penylalanine ammonia-lyase (PAL), cinnamic-4-hydroxylase (C4H), capsaicin synthase (CS), and peroxidase (POD) are involved in the capsaicinoid biosynthesis pathway and may be altered in cultivars with different pungency levels. This study clarified the action of these enzymes under drought stress for hot Capsicum cultivars with low, medium,and high pungency levels. At the flowering stage, control plants were watered at field capacity, whereas drought-induced plants were subjected to gradual drought stress. Under drought stress, PAL, C4H, CS, and POD enzyme activities increased as compared to the non-drought-stressed plants. A novel discovery was that PAL was the critical enzyme in capsaicinoid biosynthesis under drought stress because its activities and capsaicinoid increased across the different pungency levels of hot pepper cultivars examined.

Determination of Capsaicin and Dihydrocapsaicin in Some Chilli Varieties using Accelerated Solvent Extraction Associated with Solid-Phase Extraction Methods and RP-HPLC-Fluorescence

Reversed phase-HPLC with fluorescence detection of two major capsaicinoids was described. Isocratic elution using a ratio of methanol and de- ionized water (66:34, v/v) as mobile phase was used at a flow rate of 0.9 mL/min with well achieved separation within 6 min. Under optimum conditions, their analytical figures of merit for the HPLC method were validated. The linearity was in the range of 1.0-25.0 g/mL with multiple determination coefficients of higher than 0.995. The limit of detection was ranged of 0.008-0.01 g/mL. The repeatability and reproducibility of the retention time and peak area for these compounds were in good precision with their relative standard deviations (RSDs) lower than 1% and 5%, respectively. Both capsaicin and dihydrocapsaicin were extracted using an accelerated solvent extraction (ASE) of methanol as an extraction solvent for 5 min static time with 3 cycles. The methanolic extracts were subjected to clean up with C18 solid-phase extraction (SPE) with its recoveries ranking of 90.2-98.0%. The method recoveries of real samples were found to be 60.7-98.6%. The optimized extraction method were applied for the determination of the two capsaicinoids in ten vareities of hot chilli pepper samples. Total contents of capsaicinoids were found in the range of 2,307.0-9047.3 g/g DW with their corresponding Scoville heat unit (SHU) of 34,600-135,700. Additionally, the contents of capsaicinoids using external calibration method comparing with those of standard addition were not significantly different, indicating accuracy of the method. Mostly, the contents of capsaicin found in these real samples were rather higher than those of dihydrocapsaicin.

An iodine supplementation of tomato fruits coated with an edible film of the iodide-doped chitosan.

In general, the risk of numerous thyroid cancers inevitably increases among people with iodine deficiencies. An iodide-doped chitosan (CT-I) solution was prepared for dipping tomatoes to coat the fresh surface with an edible film (1.5 μm), thereby providing iodine-rich fruits for daily intake. Characterisation of the thin film was conducted by FTIR and SEM. Stability of the CT-I film was studied via water immersion at various time intervals, and no residual iodide leached out due to intrinsic interactions between the cationic amino group of chitosan and iodide ions. Moreover, the iodide supplement exhibited no effect on the antioxidant activity of tomatoes. The iodine content in the film-coated tomato was determined by ICP-OES. The tomato coating with 1.5% (w/v) CT-I contained approximately 0.4 μg iodide per gram fresh weight. In addition, the freshness and storability of iodine-doped tomatoes were also maintained for shelf-life concerns.

Using bio-dispersive solution of chitosan for green dispersive liquid–liquid microextraction of trace amounts of Cu(II) in edible oils prior to analysis by ICP–OES

A green approach using chitosan solution as a novel bio-dispersive agent for the dispersive liquid-liquid microextraction (DLLME) of trace amounts of Cu(II) in edible oils is presented. An emulsion was formed by mixing the oil sample with 300µL of 0.25% (w/v) chitosan solution containing 200µL of 6molL-1 HCl. Deionized water was used to induce emulsion breaking without centrifugation. The centrifuged Cu(II) extract was collected and analyzed using an inductively coupled plasma-optical emission spectrometer. The detection and quantitation limits were 2.1 and 6.8µgL-1, respectively. Trace amounts of Cu(II) in six edible oil samples were tested under optimum conditions for DLLME, with a recovery ranging from 90.3% to 109.3%. Therefore, the new dispersive agent in DLLME offers superior performance owing to the non-toxic nature of the solvent, short extraction time, high sensitivity, and easy operation.

A Green Extraction of Trace Iodine in Table Salts, Vegetables, and Food Products Prior to Analysis by Inductively Coupled Plasma Optical Emission Spectrometry

In this study, we report a new method for iodine extraction from table salts, vegetables, and other food products using ultrasound-assisted extraction, prior to the iodine determination by inductively coupled plasma optical emission spectrometry. For the ultrasound-assisted extraction, deionized water as the extraction solvent and an extraction time of 5 min were found to be the most optimum condition. A linear calibration curve was plotted for 0.1 to 200.0 mg L−1 iodine convention. The limits of detection and quantification were 0.049 and 0.164 mg L−1, respectively. The precision for intraand inter-day analyses was 2.75 and 4.54%, respectively. The accuracy of the method was confirmed with certified reference materials. Recoveries in 47 real samples were ranged between 80.48 and 118.1%. Therefore, the proposed method could be considered as a rapid, simple, and environmental-friendly method (the green extraction) to determine the trace amounts of iodine in different kinds of food products.

Light intensity affects capsaicinoid accumulation in hot pepper ( Capsicum chinense Jacq.) cultivars

Strong light intensity affects plant growth, fruit yield, and accumulation of capsaicinoids in hot peppers (Capsicum spp.) which are important food and medicinal products. Shading improves plant growth and fruit yield in bell pepper (Capsicum annuum), but research on the effect of shading on high pungency C. chinense cultivars is limited. This study investigated the responses of C. chinense cultivars to different light intensities to maximize capsaicinoid production. An experiment to test the effect of shading, i.e., no-shading (full light intensity as control), 50% shade and 70% shade of full light intensity, was conducted in a plastic-net house using four C. chinense cultivars with different pungency levels: Bhut Jolokia, Akanee Pirote, Orange Habanero, and BGH1719. The cultivars showed different capsaicinoid production levels depending on the shade level. The highest capsaicinoid yields were found in the F1 hybrid cultivar Akanee Pirote under 50% shading (4,820 mg/plant) and in the Bhut Jolokia cultivar under 70% shading (3,419 mg/plant). By contrast, the BGH1719 plants showed the lowest capsaicinoid production (291 mg/plant) when shade was applied. These results demonstrate that capsaicinoid production in the studied cultivars is affected by light intensity. It is recommended that growers of high pungency cultivars use the appropriate level of shading for the particular cultivar to increase capsaicinoid yield.

Influence of water stresses on capsaicinoid production in hot pepper (Capsicum chinense Jacq.) cultivars with different pungency levels

Although water stress reduces fruit yield, it also increases capsaicinoid accumulation in hot pepper. The aim of this study was to investigate the effect of different water regimes on capsaicinoid production in Capsicum chinense Jacq. having different pungency levels. Four hot pepper (C. chinense) cultivars were planted with four water regimes after anthesis: daily irrigation (control; S1), every 2 days (S2), every 3 days (S3) and every 4 days (S4). The results found that Akanee Pirote with the S2 treatment gave the highest capsaicinoid yield, and the increase of capsaicinoid yield was attributed from increasing the absolute capsaicinoid content and reducing the dry fruit yield as compared to the control. Capsaicinoid yield of Bhut Jolokia, Orange Habanero, and BGH1719 responded to the water stresses, but produced less capsaicinoid yield as compared to the control. This study reveals that appropriate water stress could increase capsaicinoid yield in some, but not all, hot pepper cultivars.