Application of antimicrobial ice for extending shelf life of fish

In this study, we investigated whether wild-thyme (Thymus serpyllum) hydrosol had a preserving effect against spoilage of freshwater fish. Sensorial characteristics, chemical freshness indicator contents, and microbial counts (total aerobes, psychrotrophics, Enterobacteriaceae, fecal coliform bacteria, Aeromonas spp., and Pseudomonas spp.) of whole ungutted and gutted Transcaucasian barb (Capoeta capoeta capoeta Guldenstaedt, 1772) stored on ice produced from wild-thyme hydrosol and tap water at 4 degrees C for 20 days were compared. The results did not reveal any significant (P > 0.05) differences in the microbial counts, sensorial characteristics, pH, and total volatile basic nitrogen values between gutted and ungutted groups. Sensory evaluation and microbiological and chemical analyses indicated that the storage of the fish on ice produced from wild-thyme hydrosol had a significant increase in shelf life by at least 15 to 20 days.     

Recrystallization of CL-20 and HNFX from Solution for Rigorous Control of the Polymorph Type: Part II,Experimental Studies

The recrystallization of CL-20 and HNFX to form different polymorphs was investigated by employing various experimental analyses, including micro-crystallization under myriad conditions, novel means of crystallization, analysis of polymorphs using powder diffraction, and Rietveld analysis. In the investigation all three groups of solvents: polar protic, non-polar aprotic, and dipolar aprotic solvents were employed. These results are reported in two parts with the experimental results reported here and the mathematical modeling results reported in Part I of this paper. The conventional crystallization techniques included combinations of solvent and anti-solvent system (including high molecular weight polymer melts), combination of solvents, the use of habit modifiers, and seeding. Other recrystallization techniques, which were also investigated included recrystallization under UV, under microwaves, upon freeze drying, upon annealing, in the presence of high molecular weight polymers, and under different hydrodynamic and hence different micro-mixing conditions.

As will be seen in Part I of this paper (this issue) our computations suggest (in agreement with earlier studies) that multiple polymorphs with various densities for both CL-20 and HNFX are possible. However, the recrystallization studies reported here revealed only one type of polymorph for HNFX, i.e., the Ci R-3 polymorph. On the other hand, CL-20 gave rise to indeed multiple polymorphs which changed with the crystallization conditions, especially with the solvent/anti-solvent systems utilized. An X-ray based method was used to determine the types of polymorphs and also the percentages of the polymorphs generated upon crystallization. The presence of multiple polymorphs or polymorph impurities in CL-20 may have significant ramifications in the sensitivity and other ultimate properties of energetic grains containing CL-20. On the other hand the existence of only one low-density polymorph for HNFX significantly limits the application areas for HNFX.     

Conversion of biomass to fuel: Transesterification of vegetable oil to biodiesel using KF loaded nano-γ-Al2O3 as catalyst

KF-impregnated nanoparticles of γ-Al₂O₃ were calcinated and used as heterogeneous catalysts for the transesterification of vegetable oil with methanol for the synthesis of biodiesel (fatty acid methyl esters, FAME). The ratio of KF to nano-γ-Al₂O₃, calcination temperature, molar ratio of methanol/oil, transesterification reaction temperature and time, and the concentration of the catalyst were used as the parameters of the study. A methyl ester yield of 97.7 ± 2.14% was obtained under the catalyst preparation and transesterification conditions of KF loading of 15 wt%, calcination temperature of 773 K, 8 h of reaction time at 338 K, and using 3 wt% catalysts and molar ratio of methanol/oil of 15:1. This relatively high conversion of vegetable oil to biodiesel is considered to be associated with the achieved relatively high basicity of the catalyst surface (1.68 mmol/g) and the high surface to volume ratio of the nanoparticles of γ-Al₂O₃.