Effect of muscle and post-mortem rate of pH and temperature fall on antioxidant enzyme activities in beef

The aim of this study was to investigate the effect of muscle, inner and outer Musculus biceps femoris (IBF and OBF respectively) and Musculus longissimus dorsi (LD), on the post-mortem rate of pH and temperature fall, and the activity of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) during simulated retail display. At day 0 of display (2 days post-mortem), the CAT and GSH-Px activities were lower in IBF than in OBF and LD (P < 0.001), and the SOD activity was lower in OBF compared to IBF and LD (P < 0.001). At day 10 of display, SOD and CAT activities had decreased in all three muscles compared to day 0 (P < 0.001), whereas the GSH-Px activity did increase with time of display. Across muscles, there were significant relationships between temperature fall, colour, lipid and colour stability and antioxidant enzyme activities.     

Influence of emulsion droplet size on antimicrobial properties

In this study the effect of oil droplet size on antimicrobial activity was investigated. Oil-in-water emulsions were made from oil possessing antimicrobial properties (lemon myrtle oil, LMO), and oil which has no antimicrobial properties (soybean oil). The antimicrobial properties were investigated against 5 bacteria. The emulsions containing millimetre size and micron-size droplets were produced by hand-shaking and blending using a high speed blender and nanoemulsions were produced using a microfluidizer at 60 MPa. It was found that all emulsions made from LMO had the same level of antimicrobial effects against the 5 bacteria whereas all soybean oil emulsions had no antimicrobial effect. From these results, it could be concluded that the antimicrobial property of nanoemulsions result from the active ingredients in the emulsions and not from high surface tensions and cell wall diffusion activity of nano-sized droplets.     

Deposition of disinfectant poly(methyl acrylate) nanocapsules onto natural rubber film via the layer‐by‐layer technique

An aqueous core containing a disinfectant agent (chlorhexidine digluconate) was encapsulated in a poly(methyl acrylate) shell with a modified nanoprecipitation technique. After redispersion of the capsules in an aqueous medium, the remaining amount of the disinfectant agent was as high as 90%. The nanocapsules were successfully adsorbed via the layer‐by‐layer technique onto a γ‐radiation‐vulcanized natural rubber latex sheet. Water contact angle measurements and scanning electron microscopy confirmed the presence of nanocapsules on the rubber surface. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Development of a monoclonal antibody-based enzyme-linked immunosorbent assay for detection of the furaltadone metabolite,AMOZ, in fortified shrimp samples

3-Amino-5-morpholinomethyl-2-oxazolidone (AMOZ) is a tissue bound metabolite of furaltadone, a synthetic nitrofuran antibiotic widely used in veterinary practices both to treat infectious diseases and as a growth promoter. Because AMOZ is carcinogenic and poses a potential health hazard for human consumers, its parent compounds, the nitrofurans, are banned from being used in animals destined for human food consumption in various countries. To enforce this, foods are routinely monitored for nitrofuran metabolite residues including AMOZ. Thus, reliable high throughput analytical methods to detect AMOZ have been developed but these are mostly based on chemical analysis. In contrast, sensitive and specific detection methods based on immunoassays for AMOZ using monoclonal antibodies have yet to be established. In this study, we report the generation of two monoclonal antibodies with high specificity for AMOZ and the development of a monoclonal antibody-based ELISA to detect AMOZ in shrimp samples using one of these clones (clone 2E5.1). Clone 2E5.1 yielded the highest sensitivity and specificity and cross reacted solely to furaltadone and AMOZ and not to other antibiotics. Competitive ELISA with 2E5.1 gave IC₅₀ values for AMOZ, CPAMOZ and furaltadone of 5.33, 0.023 and 1.330 ng/ml, respectively. When applied in ELISA to detect AMOZ in fortified shrimp samples, the detection capability and limit of detection were 0.3 and 0.16 μg/kg, respectively. Taken together, a sensitive and specific monoclonal antibody-based ELISA for AMOZ detection has been developed that could facilitate the economic and reliable high throughput monitoring of AMOZ in shrimps and potentially other food.