Optimization and validation of a method for extraction and quantification of ochratoxin A in black pepper

The extraction method for the determination of ochratoxin A (OTA) in black pepper was optimized. The influence of three variables, i.e., type of solvent, solvent-volume-to-sample-size ratio (v/w) and amount of sodium chloride (NaCl) (g), on OTA recovery was evaluated. Analysis of variance was used to compare recovery values obtained from different solvents, and response surface methodology (RSM) was used to determine the optimum amount of NaCl and the solvent-volume-to-sample-size ratio. The concentration of OTA was determined by high-performance liquid chromatography with fluorescence detection. The highest recovery (95.2 %) was obtained when methanol/water (80:20, v/v) was used as the solvent. The RSM results showed that the experimental data could be adequately fitted to a second-order polynomial model with multiple regression coefficients (R2) of 0.962. The optimum amount of NaCl was determined to be 3 g, whereas the optimum solvent-volume-to-sample-size ratio (v/w) was found to be 4. The proposed method was applied to 20 samples, and the presence of OTA was found in 8 (40%) samples ranging from 0.11 to 3.16 ng g-1

Optimisation of the determination of deoxynivalenol in wheat flour by HPLC and a comparison of four clean-up procedures.

The determination of deoxynivalenol (DON) in wheat flour by liquid chromatography with photodiode array (PDA) detection was optimised. Response surface methodology (RSM) was used to determine the optimum chromatographic conditions for the determination of DON. The influence of three variables, acetonitrile (ACN) volume in mobile phase (9.5-24.5, v/v), flow rate (0.5-1.5 ml min-1) and wavelength (215-221 nm) on DON peak area was evaluated. The best separation was achieved using a symmetry column (150×3.9 mm; particle size 5 µm) by isocratic elution (1.0 ml min-1) and a mobile phase consisting of ACN/water in the ratio 17:83 (v/v). UV detection was performed at 218 nm. Linear calibration curves were constructed in the concentration range 1-1000 ng ml-1. The detection limit measured as the signal-to-noise ratio (3:1) was 0.03 ng ml-1. RSM results showed that the experimental data could be adequately fitted to a second-order polynomial model with multiple regression coefficients (R2) of 0.968. The efficiency of four clean-up procedures for wheat flour extract was compared. Recovery of DON using a Mycosep #225 column was highest with a value of 99%, while that of Mycosep #227 was 65%. In contrast, DON recovery using immunoaffinity columns (IAC) and an Oasis® HLB column was only 53 and 42%, respectively. The trueness of the method using the Mycosep #225 column was established with a certified reference material CRM 379. The result obtained from three replicates was 0.66±0.04 µg g-1 and the certified value was 0.67 µg g-1

Kandungan Kapsaisin dalam Kultivar Capsicum annum

Thirteen cultivars of chilli Capsicum annum were used for the determination of capsaicin obtained from two stages of maturation, 25 and 40 days after flowering. The results showed that there was a significant difference (p > 0.05) in the capsaicin content among different cultivars for both stages. The range of capsaicin concentration for day 25 was 6.14 - 26.6 mg/g and 6.3 - 106.42 mg/g (dry weight) for day 40. Except for KA2 dan Abheim, other cultivars contained significantly higher concentration of capsiasin in day 40 compared to those in day 25. The range of capsaicin located in the placenta, the pericarp and the seeds was 47 - 60%, 27 - 41 %, 6 - 16%, respectively

Effects of washing pre-treatment on mercury concentration in fish tissue.

The objective of this study was to examine the effect of washing pre-treatment on mercury concentration in fish fillet. Response surface methodology was used to investigate the influence of three variables, pH (1-6.5), NaCl (0-1% w/v) and exposure time (5-30 min) by using a three-factor central composite design. The aim was to obtain the best possible combination of these variables in order to reduce mercury in fish fillet. The experimental data were adequately fitted into a second-order polynomial model with multiple regression coefficients (R(2)) of 0.961. The results indicated that the reduction of mercury in fish flesh significantly depends on the pH of the solution used. The overall optimal condition resulting in the maximum mercury reduction in fish fillet was obtained at a combined level pH of 2.79, NaCl of 0.5% and exposure time of 13.5 min. The optimized protocol produced a solution that can reduce mercury from raw fish fillet up to 81%

Natural occurrence of deoxynivalenol (DON) in wheat based noodles consumed in Malaysia

In this first study performed in noodle samples consumed in Malaysia for the presence of deoxynivalenol (DON), a total of 135 sample of noodles, comprised of instant noodle, yellow alkaline noodle and white salted noodle, were randomly collected from food stores and analyzed for DON using high performance liquid chromatography (HPLC) with a PDA (photodiode array) detector at 218 nm. The objective of this study was to investigate the DON contamination levels in different types of wheat-based noodle consumed in Peninsular Malaysia. An acetonitrile:water (17:83 v/v) mixture was used as a mobile phase and clean-up was accomplished with a Mycosep 225 column. There was a high variation in the DON concentrations in all types of noodle group as well as between brands. Only one sample of instant and yellow alkaline noodle each were contaminated with DON, at concentrations of 1.003 and 1.243 ng/g, respectively. The minimum detectable concentration for the DON was 0.627 ng/g in instant noodle. In the case of white salted noodle, none of the samples contained any detectable amount of DON. The results indicate a low occurrence of DON mycotoxins in commercial noodle products in Malaysia

Influence of noodle processing (industrial protocol) on deoxynivalenol.

The effects of processing for two types of Asian noodles production (yellow alkaline and instant) on DON levels were investigated. Deoxynivalenol (DON) level at each step of processing was determined using high performance liquid chromatography (HPLC) with a PDA (photodiode array) detector at 218 nm. An acetonitrile: water (17:83 v/v) mixture was used as mobile phase and a MycosepTM #225 column as clean-up method. Significant reductions of the initial DON levels were found, 43.2% and 66.6% in yellow alkaline and instant noodles, respectively. The presence of alkaline salt as an ingredient appeared to be the primary factor influencing the extent of reduction in the two types of noodles. The data indicated that significant reduction of DON have occurred during cooking and frying of both yellow alkaline and instant noodles, respectively. The mechanism of reduction due to cooking is probably a leaching of DON out of the noodle into the cooking medium

Biomagnifications of mercury and methylmercury in tuna and mackerel

Seawater may be contaminated by harmful substances, including toxic elements released by human activities. The present study evaluates the total mercury and methylmercury concentrations and their correlations to fish body size in longtail tuna and short-bodied mackerel from Chendring, Kuantan, at east coast and Kuala Perlis at west costs of Peninsular Malaysia during May to November 2007. Total mercury and methylmercury in muscle tissue of 69 samples of longtail tuna and short-bodied mackerel, ranged from 0.180 to 1.460 μg/g and 0.0.169-0.973 μg/g and 0.251-1.470 μg/g and 0.202-1.352, whereas the methylmercury to total mercury ratio ranged from 70% to 83%, respectively. Samples of both species from the east coast showed higher levels of mercury compared to those from west coast. In all of the locations, significant positive correlations were found between fish body weight and mercury content (R(2) > 0.470). The estimated weekly intake of total mercury and methylmercury from the consumption 66.33 g/week of short-bodied mackerel and 18.34 g/week of longtail tuna (based on local dietry survey) was found to be lower than the maximum limit of 5 and 1.5 μg/kg bodyweight established by FAO/WHO and codex, respectively

Optimization and validation of a HPLC method for simultaneous determination of aflatoxin B1, B2, G1, G2, ochratoxin A, and zearalenone using experimental design.

A reversed-phase HPLC optimization strategy is presented for investigating the separation and retention behavior of aflatoxin B 1, B 2, G 1, G 2, ochratoxin A and zearalenone, simultaneously. A fractional factorial design (FFD) was used to screen the significance effect of seven independent variables on chromatographic responses. The independent variables used were: (X1) column oven temperature (20-40°C), (X2) flow rate (0.8-1.2 ml/min), (X3) acid concentration in aqueous phase (0-2%), (X4) organic solvent percentage at the beginning (40-50%), and (X5) at the end (50-60%) of the gradient mobile phase, as well as (X6) ratio of methanol/acetonitrile at the beginning (1-4) and (X7) at the end (0-1) of gradient mobile phase. Responses of chromatographic analysis were resolution of mycotoxin peaks and HPLC run time. A central composite design (CCD) using response surface methodology (RSM) was then carried out for optimization of the most significant factors by multiple regression models for response variables. The proposed optimal method using 40°C oven temperature, 1 ml/min flow rate, 0.1% acetic acid concentration in aqueous phase, 41% organic phase (beginning), 60% organic phase (end), 1.92 ratio of methanol to acetonitrile (beginning) and 0.2 ratio (end) for X1-X7, respectively, showed good prediction ability between the experimental data and predictive values throughout the studied parameter space. Finally, the optimized method was validated by measuring the linearity, sensitivity, accuracy and precision parameters, and has been applied successfully to the analysis of spiked cereal samples

Effect of gamma radiation on reduction of mycotoxins in black pepper.

Gamma ray was applied to reduce mycotoxins, i.e. ochratoxin A (OTA) and aflatoxins B1, B2, G1 and G2 (AFB1, AFB2, AFG1 and AFG2) in black pepper. Response surface methodology (RSM) was applied to evaluate the effect of dose of gamma ray ranging from 0 to 60 kGy and mycotoxin concentration ranging from 10 to 100 ng g−1 on the mycotoxin reduction. The maximum reduction was found at 60 kGy which was 52%, 43%, 24%, 40% and 36% for OTA, AFB1, AFB2, AFG1 and AFG2, respectively. Results showed the gamma rays even at 60 kGy were not effective in completely destroying of ochratoxin and aflatoxins