Kinetics of Total Phenolic Content and Total Color Difference During Liquid Smoking of Kashar Cheese

Since the late 1800s, smoking has been used for giving color, taste, and aroma to foods, as well as for developing new products. Due to health, technical, and economic reasons, one of the widely used smoking techniques preferred by manufacturers is smoking with liquid smoke. In this study, fresh Kashar cheese slices were smoked by immersion in liquid smoke at concentrations (10, 20, 30%), smoking temperatures (20, 30, 40°C) and smoking times (30, 60, 120, 180, 300 s). The appropriate equation and kinetic parameters were determined for the variation of total phenolic content and total color difference. A pseudo-first-order kinetic model was obtained, and activation energy values were calculated as 10.7 kJ/mol and 24.3 kJ/mol, respectively.     

Improvement of PEMFC performance with Nafion/inorganic nanocomposite membrane electrode assembly prepared by ultrasonic coating technique

Membrane electrode assemblies with Nafion/nanosize titanium silicon dioxide (TiSiO₄) composite membranes were manufactured with a novel ultrasonic-spray technique and tested in proton exchange membrane fuel cell (PEMFC). Nafion/TiO₂ and Nafion/SiO₂ nanocomposite membranes were also fabricated by the same technique and their characteristics and performances in PEMFC were compared with Nafion/TiSiO₄ mixed oxide membrane. The composite membranes have been characterized by thermogravimetric analysis, scanning electron microscopy, X-ray diffraction, water uptake, and proton conductivity. The composite membranes gained good thermal resistance with insertion of inorganic oxides. Uniform and homogeneous distribution of inorganic oxides enhanced crystalline character of these membranes. Gas diffusion electrodes (GDE) were fabricated by Ultrasonic Coating Technique. Catalyst loading was 0.4 mg Pt/cm² for both anode and cathode sides. Fuel cell performances of Nafion/TiSiO₄ composite membrane were better than that of other membranes. The power density obtained at 0.5 V at 75 °C was 0.456 W cm⁻², 0.547 W cm⁻², 0.477 W cm⁻² and 0.803 W cm⁻² for Nafion, Nafion/TiO₂, Nafion/SiO₂, and Nafion/TiSiO₄ composite membranes, respectively.     

Hydroxyl‐terminated poly(urethane acrylate) as a soft liner in dental applications: Synthesis and characterization

Hydroxyl‐terminated poly(urethane acrylate)s were synthesized for use in biomedical applications. Acrylate end capping via an interesterification reaction was successfully achieved with methacryloyl chloride addition to the hydroxyl ends of the polyurethane at low temperatures. 2,4‐Toluene diisocyanate, 1,6‐hexane diisocyanate, and methylene diphenyl diisocyanate were used as diisocyanates for urethane synthesis, and they were end‐capped with methyl methacrylate and hydroxyethyl methacrylate. The nature of the monomers that we used had an effect on the thermal and morphological properties that were interpreted in terms of the level of hydrogen bonding and the degree of phase separation. The synthesized polymers were characterized by NMR, Fourier transform infrared/attenuated total reflectance spectroscopy, differential scanning calorimetry, thermogravimetric analysis, and gel permeation chromatography. The number‐average molecular weights of the poly(urethane acrylate)s were 2500–6000 g/mol. To use the polymer as a soft‐liner material in denture applications, the residual isocyanate should not exist. In this study, we showed that a prepolymer without residual isocyanate could be synthesized. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Influence of SiC addition on tribological properties of SiAlON

The tribological properties of gas pressure sintered SiAlON and its composite with 18 wt% silicon carbide (SiC) against two different mating materials, i.e., alumina and SiAlON are evaluated. SiAlON and SiAlON–18%SiC composite ceramics were prepared by pressure less sintering and gas pressure sintering. Fretting wear tests were carried out under dry unlubricated ambient conditions (room temperature 23–25 °C; relative humidity 50–55%) with a load of 8 N for 45,000 cycles. Friction and wear properties of SiAlON–SiC proved better than the monolithic SiAlON. The formation of silica roll like structure on the composite worn surface was observed.     

Critical phenomenon during photoinitiated gelation at different temperatures: A Photo-DSC study

The behaviour of photoinitiated radical polymerization of an 80 wt% epoxy diacrylate (EA) and 20 wt% tripropyleneglycoldiacrylate (TPGDA) mixture with 2-mercaptothioxanthone (TX-SH) photoinitiator was studied at different temperatures by using photo-differential scanning calorimetric (Photo-DSC) technique. All photopolymerization reactions were carried out under the same conditions. It was observed that all conversion curves during gelation at different temperatures present nice sigmoidal behaviour which suggests the application of the percolation model. Observations around the critical time, called the glass transition point (t_g), taken to reach the maximum rate of polymerization (Rp_max) show that the gel fraction exponent (β) obeyed the percolation model. The produced β values were found to be around 0.50, predicting that the system under consideration belongs to the same universality class. However, Rp_max and the final conversion (C_s) values were found to increase when the temperature was increased up to a certain value. On the other hand, t_g values decreased and became saturated as the temperature was increased.     

Design and Implementation of Fuel Cell and Photovoltaic Panel-Supported Ozonation System

It is normal for a produced agricultural product or food to be transported to distances far from where it is produced. However, it is important to keep the product fresh in this transportation. There are many methods used to extend the life of the food during transport. The chemical method is the most used. However, the chemical method is harmful to human health. One of the methods used for storing, preserving and transporting agricultural products is ozonation and air conditioning. In this study, a system was designed to extend the life of the product in the storage and transport of food products. With the developed system, temperature, relative humidity and ozone were produced and their amounts were controlled according to the type of product being carried. In the design, polymer exchange membrane fuel cell was used for the required oxygen. The energy requirement of the system was provided by a photovoltaic panel to get rid of the generator dependency on supplied electrical power. The applicability of the system to refrigerated vehicles, especially those used in food transportation, was examined.     

In situ reactive extraction of lactic acid from fermentation media

Extractive lactic acid fermentation was investigated in the presence of sunflower oil and Alamine‐336 (with oleyl alcohol as the diluent solvent). Lactic acid was produced in various media at 37 °C using Lactobacillus delbrueckii (NRRL‐B 445). First, the effects of oleyl alcohol (33.3%, v/v), immobilisation, and immobilisation in the presence of sunflower oil (5, 10, 15%, v/v) on lactic acid production were investigated. It was found that oleyl alcohol did not affect production while addition of sunflower oil increased lactic acid production from 10.22 to 16.46 gdm^?3. On the other hand, a toxic effect was observed for oleyl alcohol solutions containing 15–50% (v/v) Alamine‐336. A maximum total lactic acid concentration of 25.59 gdm^?3 was obtained when an oleyl alcohol solution containing 15% (v/v) Alamine together with immobilised cells with 15% (v/v) sunflower oil was used. This value was about 2.5 times that obtained from fermentation without organic solutions. © 2001 Society of Chemical Industry     

Continuous fermentative hydrogen production from cheese whey wastewater under thermophilic anaerobic conditions

Hydrogen (H₂) production from cheese processing wastewater via dark anaerobic fermentation was conducted using mixed microbial communities under thermophilic conditions. The effects of varying hydraulic retention time (HRT: 1, 2 and 3.5 days) and especially high organic load rates (OLR: 21, 35 and 47 g chemical oxygen demand (COD)/l/day) on biohydrogen production in a continuous stirred tank reactor were investigated. The biogas contained 5–82% (45% on average) hydrogen and the hydrogen production rate ranged from 0.3 to 7.9 l H₂/l/day (2.5 l/l/day on average). H₂ yields of 22, 15 and 5 mmol/g COD (at a constant influent COD of 40 g/l) were achieved at HRT values of 3.5, 2, and 1 days, respectively. On the other hand, H₂ yields were monitored to be 3, 9 and 6 mmol/g COD, for OLR values of 47, 35 and 21 g COD/l/day, when HRT was kept constant at 1 day. The total measurable volatile fatty acid concentration in the effluent (as a function of influent COD) ranged between 118 and 27,012 mg/l, which was mainly composed of acetic acid, iso-butyric acid, butyric acid, propionic acid, formate and lactate. Ethanol and acetone production was also monitored from time to time.To characterize the microbial community in the bioreactor at different HRTs, DNA in mixed liquor samples was extracted immediately for PCR amplification of 16S RNA gene using eubacterial primers corresponding to 8F and 518R. The PCR product was cloned and subjected to DNA sequencing. The sequencing results were analyzed by using MegaBlast available on NCBI website which showed 99% identity to uncultured Thermoanaerobacteriaceae bacterium.     

Conducting copolymers of polypyrrole/polytetrahydrofuran

Summary Bifunctional living polytetrahydrofuran (PTHF) was terminated with potassium salt of pyrrole to yield polymers with electrochemically active end groups. These polymers were employed in the second stage to obtain conducting polypyrrole/polytetrahydrofuran block copolymers with short and long polytetrahydrofuran segments by potentiostatic anodic polymerization of pyrrole in different electrolytic media. Syntheses of block copolymers were achieved in media where tetrabutylammonium fluoroborate, sodium perchlorate and sodium p-toluenesulfonate were used as the supporting electrolytes. Characterizations were based on DSC, TGA, SEM, FTIR, and CV analyses. No significant effect of the chain length of polytetrahydrofuran segments on the properties of the copolymers was observed; however, thermal, electrochemical behaviors, and surface morphologies of the films were greatly affected by the supporting electrolytes. Received: 5 January 1998/Revised version: 25 March 1998/Accepted: 27 March 1998     

Ultrasound- and Microwave-Assisted Extractions Facilitate Oil Recovery from Gilthead Seabream (Sparus aurata) By-Products and Enhance Fish Oil Quality Parameters

This research aimed to analyze ultrasound (UAE) and microwave-assisted extraction (MAE) as novel technologies for utilizing gilthead seabream (Sparus aurata) by-products to produce high-quality fish oil for human consumption. The impacts of extraction parameters, namely, temperature, time, solvent-to-solid ratio, and their interactions on the extraction yield, are investigated using response surface methodology (RSM), and a central composite rotatable design. The optimized conditions are 15.47 mL g⁻¹ of solvent-to-solid ratio, 38 min, and 42 °C for UAE and 15.84 mL g⁻¹ of solvent-to-solid ratio, 18 min, and 40 °C for MAE. Under optimal conditions, the maximum extraction yields are 38.40 and 36.70% (g/g) for UAE and MAE, respectively. Both UAE and MAE have significantly higher mass transfer rates (61.70 and 121.58 g h⁻¹, respectively) than Soxhlet extraction (10.78 g h⁻¹). The fatty acid composition, physicochemical, and oxidation analyses of fish oils confirm the suitability of both UAE and MAE for the recovery of high-quality oils from fish processing by-products. The valorized oils mainly include unsaturated fatty acids (≈75%) and are rich in oleic acid. Furthermore, scanning electron microscopy analysis reveals that the key driving force for fast oil extraction is the structural degradation of fish by-products caused by ultrasound and microwave. Practical Applications: Due to environmental and economic viewpoints, the validation of fish oil from fish industry by-products has become a popular research topic recently. Alternative recovery techniques such as ultrasound- (UAE) and microwave-assisted extraction (MAE) protocols may have additional benefits in producing functional oils. Interactive effects of process parameters determine the success of the extraction technique; therefore optimization is a critical approach when applying the extraction protocols. This study shows that UAE and MAE techniques significantly enhanced oil extraction rate from gilthead seabream (Sparus aurota) by-products at lower temperatures and by using lower amounts of solvent. UVA and MAE increase oxidative stability and do not change the fatty acid composition. Hence, the by-product of the gilthead seabream can be a sustainable and food-grade fish oil source and UAE and MAE can be a good alternative to the conventional (Soxhlet) extraction by providing high yield and quality oil.