Aflatoxin (B1, B2, G1, and G2) Contamination in Rice of Mexico and Spain,from Local Sources or Imported

Rice is an important cereal but it is often contaminated with aflatoxins (AFs). The purpose of this study was to identify and quantify AF (B₁, B₂, G₁, and G₂) in 67 rice samples cultivated in Mexico and Spain, and from imported crops collected in 2008 and 2009. The methodology was validated, the rice samples were concentrated and purified with immunoaffinity columns and were quantified by high‐pressure liquid chromatography (HPLC). The average total AF (AFt) in the Spanish rice was 37.3 μg/kg, the range was from 1.6 to 1383 μg/kg, the most contaminated samples being from San Juan de Aznalfarache, Sevilla (AFt = 138.6 μg/kg), from Tortosa, Tarragona (AFt = 104.6 μg/kg), and Calasparra, Murcia (AFt = 103.9 μg/kg). The rice imported from France to Spain had AFt of 26.6 μg/kg and from Pakistan AFt of 18.4 μg/kg, showing less AF contamination than the local one. The rice which originated from Mexico contained (AFt = 16.9 μg/kg), and those imported from the United States (AFt = 14.4 μg/kg) and Uruguay (AFt = 15.6 μg/kg). The imported rice had better quality in terms of the presence of AFs.     

Tautomerism and Reactions of 1H-1,2,4-Triazole-5-thiones with Hydrazonoyl Halides

The acid dissociation constants (K_a) of a series of 3,4-diaryl-1H-1,2,4-triazole-5-thiones ( 1 ) were determined and were found to correlated linearly with Hammett substituent constants; log K_a = 1.06 σ_x − 11.01. Such a result indicates that 1 exists essentially in one tautomeric form namely the thione form. Reactions of 1 with hydrazonoyl chlorides 2 gave the thiohydrazides 5 . Similiar reaction of 3-phenyl-1H(4H)- 1,2,4-triazole-5-thione 1g with 2a gave the thiohydrazide 5h which was converted into 1,3,5-triphenyl-1,2,4-triazolo[3,4-c]-1,2,4-triazole ( 9 ). The latter was also prepared from 3-phenyl-5-methylthio-4H-1,2,4-triazole ( 6 ) and 2a . The mechanism of the reaction of 1 with 2 is discussed.     

Zein-Based Films Containing Monolaurin/Eugenol or Essential Oils with Potential for Bioactive Packaging Application

Zein is renewable plant protein with valuable film-forming properties that can be used as a packaging material. It is known that the addition of natural cross-linkers can enhance a film’s tensile properties. In this study, we aimed to prepare antimicrobial zein-based films enriched with monolaurin, eugenol, oregano, and thyme essential oil. Films were prepared using the solvent casting technique from ethanol solution. Their physicochemical properties were investigated using structural, morphological, and thermal techniques. Polar and dispersive components were analyzed using two models to evaluate the effects on the surface free energy values. The antimicrobial activity was proven using a disk diffusion method and the suppression of bacterial growth was confirmed via a growth kinetics study with the Gompertz function. The films’ morphological characteristics led to systems with uniform distribution of essential oils or eugenol droplets combined with a flat-plated structure of monolaurin. A unique combination of polyphenolic eugenol and amphiphilic monoglyceride provided highly stretchable films with enhanced barrier properties and efficiency against Gram-positive and Gram-negative bacteria, yeasts, and molds. The prepared zein-based films with tunable surface properties represent an alternative to non-renewable resources with a potential application as active packaging materials.     

Transmission of video telephony images over wireless channels

In this paper, the effects of digital transmission errors on H.263 codecs are analyzed and the transmission of H.263 coded video over a TDMA radio link is investigated. The impact of channel coding and interleaving on video transmission quality is simulated for different channel conditions. Fading on radio channels causes significant transmission errors and H.263 coded bit streams are very vulnerable to erros. Powerful Forward Error Correction (FEC) codes are therefore necessary to protect the data so that it can be successfully transmitted at acceptable signal power levels. FEC, however, imposes a high bandwidth overhead. In order to make best use of the available channel bandwidth and to alleviate the overall impact of errors on the video sequence, a twolayer data partitioning and unequal error protection scheme based on H.263 is also studied. The scheme can tolerate more transmission errors and leads to more graceful degradation in quality when the channel SNR decreases. In lossy environments, it can improve the video transmission quality at no extra bandwidth cost.Part of this paper was presented at IS&T/SPIE Symposium on Electronic Imaging, San Jose, CA, USA, January 1996.     

Effect of freeze storage on the volatiles of butter

The changes in the volatile components of three butter samples were studied during freeze storage for 7.5 months. The amount of carbonyl increased and reached a maximum after 4.5 months of storage. Afterwards the carbonyl decreased. The lactons reached its maximum after storage of 3 month. The increase of the carbonyls caused by peroxidation of unsaturated fatty acids was taken as indication for the deterioration of the butter samples during storage.     

Using a pulse generator to check flux meters

Measurement Techniques -