Sana Jawaid

Rapid detection of melamine adulteration in dairy milk by SB-ATR-Fourier transform infrared spectroscopy

Melamine is a nitrogenous chemical substance used principally as a starting material for the manufacture of synthetic resins. Due to its very high proportion of nitrogen melamine has been added illegitimately to foods and feeds to increase the measured protein content, which determines the value of the product. These issues prompted private as well as governmental laboratories to develop methods for the analysis of melamine in a wide variety of food products and ingredients. Owing to this fact present study is aimed to use single bounce attenuated total reflectance (SB-ATR) Fourier transform infrared spectroscopy (FTIR) method as an effective rapid tool for the detection and quantification of melamine in milk (liquid and powder). Partial least-squares (PLS) models were established for correlating spectral data to melamine concentration with R(2)>0.99, and RMSEC 0.370. Linear calibration curves were obtained over the calibration range of 25-0.0625%. The LOD and LOQ of the method was 0.00025% (2.5 ppm) and 0.0015% (15 ppm) respectively. Proposed SB-ATR-FTIR method requires little or no sample preparation with an assay time of 1-2 min.

A highly selective and sensitive electrochemical determination of melamine based on succinic acid functionalized copper oxide nanostructures

This study presents the development of a highly selective and sensitive electrochemical sensor for the determination of melamine from aqueous environments. The sensor system is based on functionalised marigold-like CuO nanostructures fabricated using a controlled hydrothermal process, where the utilised succinic acid is considered to play a dual role as a functionalising and growth controlling agent (modifier). The fabricated nanostructures exhibit sharp and well-ordered structural features with dimensions (thickness) in the range of 10–50 nm. The sensor system exhibits strong linearity within the concentration range of 0.1 × 10−9 to 5.6 × 10−9 M and demonstrates an excellent limit of detection up to 0.1 × 10−10 M. The extreme selectivity and sensing capability of the developed sensor is attributed to the synergy of selective interaction between succinic acid and melamine moieties, and the high surface area of marigold-like CuO nanostructures. In addition to this, the developed sensor was also utilised for the determination of melamine from real milk samples collected from different regions of Hyderabad, Pakistan. The obtained excellent recoveries proved the feasibility of the sensor for real life applications. The sensor system offers an operative measure for detecting extremely low melamine content with high selectivity in food contents.

Quick determination of melamine in infant powder and liquid milk by Fourier transform infrared spectroscopy

A simple, cost-effective and environmentally friendly analytical method was developed for the quantification of melamine (MEL) in liquid milk and infant powder by using transmission Fourier transform infrared (FT-IR) spectroscopy. Standards and samples were analyzed in the form of a KBr pellet for recording FT-IR spectra. Partial least squares calibration was established in the FT-IR region, 851.62–798.39 cm−1, with a linear range of 0.001–1%. An excellent coefficient of determination (R2) of 0.9999 was achieved, with minimum errors in the root mean square error of calibration and the root mean square error of prediction, for which the values were 0.17 and 3.49, respectively. The accuracy of the calibration model was also verified using the root mean square error of cross-validation, which was found to be 2.25. The limit of detection and the limit of quantification of the method were 0.0001% (1 ppm) and 0.00035% (3.5 ppm), respectively. The method was successfully applied to liquid and infant powder milk samples and gave good recoveries (98.9–100.2%). The FT-IR method developed here is efficient, accurate and appropriate for MEL detection in the dairy industry, with a reduced cost and a short analysis time.

Synthesis of Highly Stable Cobalt Nanomaterial Using Gallic Acid and Its Application in Catalysis

We report the room temperature (25–30°C) green synthesis of cobalt nanomaterial (CoNM) in an aqueous medium using gallic acid as a reducing and stabilizing agent. pH 9.5 was found to favour the formation of well dispersed flower shaped CoNM. The optimization of various parameters in preparation of nanoscale was studied. The AFM, SEM, EDX, and XRD characterization studies provide detailed information about synthesized CoNM which were of 4–9 nm in dimensions. The highly stable CoNM were used to study their catalytic activity for removal of azo dyes by selecting methyl orange as a model compound. The results revealed that 0.4 mg of CoNM has shown 100% removal of dye from 50 μM aqueous solution of methyl orange. The synthesized CoNM can be easily recovered and recycled several times without decrease in their efficiency.

Contamination profile of aflatoxin M1 residues in milk supply chain of Sindh, Pakistan

Aflatoxin M1 (AFM1) is a potent carcinogen, teratogen and mutagen found in the milk when lactating animals consume feed contaminated with aflatoxin B1 (AFB1). In the present study, the contamination of AFM1 was evaluated in the milk supply chain of the province of Sindh, Pakistan. For the broader profiling of targeted toxin, enzyme-linked immunosorbent assay (ELISA) was used for the determination of AFM1 in both branded and non-branded milk samples. The results showed that 96.43% of samples (81 out of 84) were contaminated with AFM1 in the range of 0.01–0.76 μg/L. The average contamination level was 0.38 μg/L. The determined values of AFM1 in the collected milk samples were above the standard limit of the European Commission while 70% of the samples exceeded levels established by United States regulations. According to these results, the estimated daily intake of AFM1 for adults was determined as 3.1 ng/kg of body weight per day.

One-pot conjugated linoleic acid production from castor oil by Rhizopus oryzae lipase and resting cells of Lactobacillus plantarum

Conjugated linoleic acid (CLA) has attracted as novel type of fatty acids having unusual health-promoting properties such as anticarcinogenic and antiobesitic effects. The present work employed castor oil as substrate for one-pot production of CLA using washed cells of Lactobacillus plantarum (L. plantarum) and lipases as catalysts. Among the screened lipases, the lipase Rhizopus oryzae (ROL) greatly assisted resting cells to produce CLA. Mass spectral analysis of the product showed that two major isomers of CLA were produced in the reaction mixture i.e. cis-9, trans-11 56.55% and trans-10, cis-12 43.45%. Optimum factors for CLA synthesis were found as substrate concentration (8 mg/mL), pH (6.5), washed cell concentration (12% w/v), and incubation time of 20 h. Hence, the combination of ROL with L. plantarum offers one pot production of CLA selectively using castor oil as a cost-effective substrate.

Essential long chain polyunsaturated fatty acids in muscle tissue of freshwater fish Labeo calbasu under different cooking processes

The effect of different cooking methods (Raw, steaming, microwave cooking, baking, grilling, pan frying and deep frying) on proximate composition and fatty acid profile of Labeo calbasu fish species from Pakistan were analyzed to determine the nutritional qualities in terms of the long chain n-3 PUFA particularly EPA and DHA. In all cooking methods moisture content decrease and protein content increased as compare to raw sample. The moisture content of fish sample seemed to be inversely related to the total extractable lipid content. In steamed, microwave, baked, grilled and pan fried methods MUFA were the abundant fatty acids followed by SFA and PUFA. Deep fried fish sample had the opposite trend having highest PUFA as contrast to MUFA and SFA. Long chain n-3 PUFA were found higher in contrast to n-6 PUFA in all other cooking methods excluding deep frying. The results indicates that steamed and grilled cooking are the best cooking method for healthy eating as they contain more n-3 PUFA (EPA and DHA). Losses of n-3 content in pan fried and deep fried fish were higher than those of fish cooked by other methods.