The Effect of Thyme and Garlic Oil on the Preservation of Vacuum-Packaged Hot Smoked Rainbow Trout (<Emphasis Type="Italic">Oncorhynchus mykiss</Emphasis>)

Quality and shelf life of filleted hot smoked rainbow trout packaged in vacuum packaging (untreated) and with thyme oil (TO), and garlic oil (GO)-treated, after vacuum-packaged (VP) conditions stored at 2 °C, were investigated by measurement of microbiological, sensory and physicochemical analyses. Acceptability scores for appearance, odour, taste and texture of untreated and treated smoked trout decreased with storage time. The limit of sensory acceptance was reached after 5 weeks for the untreated samples, after 7 weeks for with thyme oil-treated samples (TO + VP) and after 6 weeks for with garlic oil-treated (GO + VP) samples. Total viable count evaluated that thyme oil- and garlic oil-treated vacuum-packaged samples had good results up to 7 weeks compared with 5 weeks in control vacuum packs. Psychrotrophic counts for untreated and treated samples exceeded 6 log cfu/g after 5 and 6 weeks of cold storage, respectively. Treated samples presented the lowest lactic acid bacteria counts. Total volatile basic nitrogen and trimethylamine nitrogen values gave acceptable results for up to 5 weeks for the untreated samples, 7 weeks for thyme- and garlic oil-treated samples. Treated with thyme oil samples presented the lowest thiobarbituric acid index values. The results obtained from this study showed that the shelf life of hot smoked rainbow trout stored in cold storage (2 °C), as determined by overall acceptability of all data, is 5 weeks for vacuum-packaged samples and 7 weeks for thyme- and garlic oil-treated vacuum-packaged smoked fish.     

Gutted and Un-Gutted Sea Bass (Dicentrarchus Labrax) Stored in Ice: Influence on Fish Quality and Shelf-Life

The sensory characteristics, chemical freshness indicator contents, and microbial counts (total aerobe, psychrotrophic bacteria, H₂S-producing bacteria, and Pseudomonas spp.) of whole un-gutted and gutted sea bass stored in ice were compared. Results of this study indicated that the acceptability quality of whole and gutted sea bass as determined by sensorial data is 11 days, respectively. No significant differences (p > 0.05) were found in the level of sensory score between whole and gutted sea bass samples. Total volatile basic nitrogen (TVB-N) values showed no significant increase for whole and gutted sea bass during storage. Trimethylamin (TMA-N) values of whole and gutted sea bass increased very slowly, reaching final values of 3.94 and, 3.38 mg/100g, respectively (day 13). Development of initial decomposition (after 7 days) occurred when bacterial counts were > 4 log CFU/g. Microbial counts showed a significant increase for whole and gutted sea bass during storage. Significant differences (p < 0.05) were found in the microbial counts between whole and gutted sea bass samples. This difference, may be attributed either to gutting procedures, which most probably were the cause of cross-contamination of fish or to the significantly higher fish flesh surface area exposed to environmental microbial contamination in the case of gutted fish.     

Synthesis and Characterization of Konjac Gum/Polyethylene Glycol-Silver Nanoparticles and their Potential Application as a Colorimetric Sensor for Hydrogen Peroxide

Journal of Inorganic and Organometallic Polymers and Materials - Green and low-cost synthesis strategies for ultrasonic preparation of polymer blend matrix-based silver nanoparticles (Ag NPs) and...     

Analogue of the Kelley condition for optimal systems with retarded control

In this paper, we consider an optimal control problem with retarded control and study a larger class of singular (in the classical sense) controls. The Kelley and equality type optimality conditions are obtained. To prove our main results, we use the Legendre polynomials as variations of control.     

The effects of carrageenan and pectin on some quality characteristics of low-fat beef frankfurters

Effects of carrageenan (0.3, 0.5, or 0.7%) and carrageenan (0.3, 0.5, or 0.7%) with a pectin gel (20%) on some quality characteristics of low-fat beef frankfurters were evaluated in comparison to a high-fat control (HFC) and a low-fat control (LFC). While low-fat frankfurters had <3.0% fat, 73-76% moisture, 13-14% protein, HFC had 17% fat, 59% moisture, and 14% protein. A reduction of 50-59% in cholesterol was determined in low fat beef frankfurters as compared to HFC (P<0.05). Better process yield and emulsion stability, and less purge were observed with increasing carrageenan concentration. Treatment groups showed higher water holding capacity (WHC) than LFC, and lower WHC than HFC (P<0.05). With increasing carrageenan concentration, WHC increased and penetrometer value decreased in low-fat frankfurters.     

Quality characteristics of spent layer<Emphasis Type="Italic"> surimi</Emphasis> during frozen storage

The effects of different washing solutions and cryoprotectants on quality characteristics of spent layer surimi were studied during frozen storage at –18 °C. The highest (P<0.05) process yield was obtained with 0.5% sodium bicarbonate and 0.04 M sodium phosphate buffer solutions. While washing resulted in decreases (P<0.05) in protein, fat, cholesterol and ash contents, collagen and myofibrillar protein showed increases compared to the unwashed mince. A cryoprotectant mixture of 2% sucrose+2% sorbitol+0.3% sodium pyrophosphate resulted in higher water-holding capacity, except for surimi washed with 0.04 M sodium phosphate buffer solution, and lower cooking loss (P<0.05) than a cryoprotectant mixture of 4% sucrose+2.8% sorbitol. Increased lightness and decreased redness was observed as a result of washing with all solutions (P<0.05).     

Adsorption of dark compounds with bentonites in apple juice

The adsorption equilibrium of dark-coloured compounds from apple juice has been investigated as a function of several variables including activation conditions of bentonite (heat and acid treatments), clay concentrations (2×10⁻³-8×10⁻³ kg clay/dm³ apple juice) and temperature (range of 296-336 K). The adsorption efficiency with acid-activated bentonite was greater than that with heat-activated and native bentonite, depending on surface properties; specific surface areas were 95.31, 71.95 and 71.76 m²/g, respectively.Absorbance data at 420 nm were fitted reasonably well with the Langmuir and Freundlich isotherms. The parameters K, Q₀, K_fr and n were determined for different temperatures. Thermodynamic parameters such as Gibbs free energy (ΔG), enthalpy (ΔH) and entropy (ΔS) change of adsorption were determined as about −3.125, 9.43 and 0.039 kJ mol⁻¹ K⁻¹, respectively, for acid-activated bentonite. These parameters were also determined for native and heat-activated bentonites. It was shown that the adsorption process was endothermic, spontaneous and controlled by physical mechanism. The adsorption and desorption rate constants (k_a and k_d) were obtained separately by applying a geometric approach to the first-order Langmuir model. k_a varied from 5.717×10⁻⁴ to 20.667×10⁻³ s⁻¹ and k_d from 1.425×10⁻⁴ to 7.473×10⁻³ s⁻¹. The results showed that acid-activated bentonite is more suitable for the adsorption of dark compounds from apple juice.