Preservation of precut white cheese by modified atmosphere packaging

Effects of modified atmosphere packaging (MAP) on storage stability and quality of precut fresh and aged white cheese were investigated. Fresh or aged white cheese was cut into small cubes and packaged in five different atmospheres [0% O₂ + 0% CO₂ + 100% N₂ (MAP1), 10% O₂ + 0% CO₂ + 90% N₂ (MAP2), 0% O₂ + 75% CO₂ + 25% N₂ (MAP3), 10% O₂ + 75% CO₂ + 15% N₂ (MAP4) and aerobic (air)]. Control samples were packaged in brine and vacuum for fresh and aged white cheese, respectively. Changes in gas composition, total plate count, lactococci, lactobacilli, yeast and mould counts, proteolysis, lipolysis, pH, colour, texture and sensory properties were investigated during refrigerated storage. The best packaging treatment for the fresh cheese was MAP3, as it inhibited mould growth and protected the hardness. MAP2 can be recommended for the packaging of the aged cheese, as it decreased lipolysis.     

Foliar epidermal anatomy of some selected wild edible fruits of Pakistan using light microscopy and scanning electron microscopy

The present study is focused on the detailed foliar epidermal anatomy of some selected wild edible fruits (WEFs) from Pakistan using light microscopy (LM) and scanning electron microscopy (SEM). The studied species are Ficus racemosa L., Solanum nigrum L., Capparis spinosa L., Physalis divaricata D.Don, Rosa moschata Herrm. and Ribes orientale Desf. collected from various localities of Pakistan. The objective of the present study is to investigate qualitative and quantitative anatomical characters for the identification and differentiation of collected wild edible fruits. The characters studied are shape and size of epidermal cells, anticlinal wall pattern, trichome type and shape, average number of stomata, length and width of stomata and pore. The detailed microscopic investigation and variations in the characters recorded have a key role in the determination and authentication of wild edible fruits. This study possesses great potential for plant taxonomists to further evaluate the species at molecular and genetic levels.     

Causes of Collapse and Damage to Low-Rise RC Buildings in Recent Turkish Earthquakes

This study assesses performance objectives defined in the Turkish Earthquake Code (TEC) in order to make a realistic evaluation related to heavy damage and collapse reasons of reinforced concrete (RC) buildings that experienced severe earthquakes in Turkey. A series of three-dimensional RC buildings with different characteristics and representing low-rise structures damaged and collapsed in the earthquake areas is designed according to Turkish codes (Turkish Design Standards and Turkish Earthquake Code). Pushover analyses are carried out to determine nonlinear behavior of the buildings under earthquake loads. Building performances are determined by using the displacement coefficients method, which is a commonly used nonlinear static evaluation procedure for different seismic hazard levels defined in the TEC. The stipulated performance objectives in the TEC are checked in terms of plastic rotations and maximum story drift. From the results of this research, it can be concluded that low-rise RC buildings designed according to Turkish codes sufficiently provide for the performance objectives stipulated in the TEC. Reasons for the heavy damages and collapses of RC buildings during severe earthquakes are explained by commonly occurring themes (i.e., project errors, poor quality of construction, modifications of buildings, etc.).     

The effects of fermentation on the thermostability of the yellow-orange pigments extracted from cactus pear (Opuntia ficus-indica)

 Cactus pear (Opuntia ficus-indica) juice with a total soluble solids content of 15.94 °Brix was fermented using the wine yeast Saccharomyces cerevisiae. A 94.54% conversion of fermentable sugar was achieved with an ethanol production of 55.3 ml/l. The pigment degradation was found to be 17% at the end of the time allowed for fermentation. However, the fermentation had actually ceased due to depletion of fermentable sugars after 12 h, a point at which only 9.4% pigment degradation was observed and there was no further total soluble solids degradation. The thermal stability of the yellow-orange pigment of the fermented juice was determined as a function of temperature at pH 5.0. The kinetic experiments were carried out at three different temperatures, 50, 70 and 90  °C. For a pseudo-first order thermal degradation rate the reaction rate constants were determined to be 0.0066, 0.0206 and 0.1244 min^–1 for temperatures of 50, 75 and 90  °C, respectively. The activation energy was calculated as 15.71 kcal mole^–1. The fermentation process did not affect the thermostability of the pigment extract. Received: 10 January 2000 / Revised version: 31 March 2000     

Mechanical and thermal properties of wood‐plastic composites reinforced with hexagonal boron nitride

Mechanical, thermal, and morphological properties of injection molded wood‐plastic composites (WPCs) prepared from poplar wood flour (50 wt%), thermoplastics (high density polyethlyne or polypropylene) with coupling agent (3 wt%), and hexagonal boron nitride (h‐BN) (2, 4, or 6 wt%) nanopowder were investigated. The flexural and tensile properties of WPCs significantly improved with increasing content of the h‐BN. Unlike the tensile and flexural properties, the notched izod impact strength of WPCs decreased with increasing content of h‐BN but it was higher than that of WPCs without the h‐BN. The WPCs containing h‐BN were stiffer than those without h‐BN. The tensile elongation at break values of WPCs increased with the addition of h‐BN. The differential scanning calorimetry (DSC) analysis showed that the crystallinity, melting enthalpy, and crystallization enthalpy of the WPCs increased with increasing content of the h‐BN. The increase in the crystallization peak temperature of WPCs indicated that h‐BN was the efficient nucleating agent for the thermoplastic composites to increase the crystallization rate. POLYM. COMPOS., 35:194–200, 2014. © 2013 Society of Plastics Engineers     

Influence of turkey meat on residual nitrite in cured meat products

A response surface experimental design was employed to estimate residual nitrite level at various initial nitrite concentrations, percent turkey meat in the formula, and heat quantity (F) values using a typical wiener as the test system. Pork and mechanically separated turkey were used as the meat ingredients. Residual nitrite and pH were measured at day 1, 7 days, 14 days, and 49 days after processing. Protein, fat, salt, moisture, and CIE (L*a*b*) color values were also determined. Results showed that the effect of turkey meat on residual nitrite level was significant (P < 0.01). An increased amount of turkey meat in the formula resulted in lower residual nitrite levels at a fixed pH. The residual nitrite level was initially proportional to initial nitrite concentration, but it became a nonsignificant factor during longer storage time. Differences in heat quantity had a significant effect (P < 0.05) on residual nitrite level initially. Greater heat quantity decreased residual nitrite level in finished cured meat products at a fixed pH. However, this effect became nonsignificant during longer storage. Reduction of residual nitrite in wieners because of turkey meat addition at a fixed pH was due to characteristics of the turkey tissue, but the mechanism of action remains unknown. It was also established that commercial wieners had a higher pH if poultry meat was included in the formulation.     

Lipid Oxidation in Poultry Döner Kebab: Pro-oxidative and Anti-oxidative Factors

ABSTRACT: The effect of mechanically separated turkey (MST), ascorbate, and vacuum packaging on rates of lipid oxidation in chicken döner kebab during storage at 4 °C or -20 °C was investigated. MST and MST/ascor-bate accelerated lipid oxidation compared to control kebab. Ascorbate application and vacuum packaging inhibited lipid oxidation. The antioxidative effect of ascorbate in the absence of MST was converted to a pro-oxidative effect in the presence of MST. This suggests that the excess lipid hydroperoxides and iron complexes in MST were activated as lipid oxidation catalysts by ascorbate to overwhelm the ability of ascorbate to inhibit lipid oxidation at lower concentrations of hemoglobin, iron, and peroxides.     

The characterization and differentiation of higher plants by fourier transform infrared spectroscopy

Several techniques have been used to identify and classify plants. We proposed Fourier transform infrared (FT-IR) spectroscopy, together with hierarchical cluster analysis, as a rapid and noninvasive technique to differentiate plants based on their leaf fragments. We applied this technique to three different genera, namely, Ranunculus (Ranunculaceae), Acantholimon (Plumbaginaceae), and Astragalus (Leguminoseae). All of these genera are angiosperms and include a large number of species in Turkey. Ranunculus and Acantholimon have ornamental importance, while Astragalus is an important pharmaceutical genus. The FT-IR spectra revealed dramatic differences, which indicated the variations in lipid metabolism, carbohydrate composition, and protein conformation of the genera. Moreover, cell wall polysaccharides including diverse groups could be identified for each genus. Acantholimon was found to have the highest hydrogen capacity in its polysaccharide and proteins. A higher lignin content and a lower occurrence of decarboxylation and pectin esterification reactions were appointed for Ranunculus and Astragalus compared to Acantholimon. All these results suggested that FT-IR spectroscopy can be successfully applied to differentiate genera, as demonstrated here with Ranunculus, Astragalus, and Acantholimon. In addition, we used this technique to identify the same species from different geographical regions. In conclusion, the current FT-IR study presents a novel method for rapid and accurate molecular characterization and identification of plants based on the compositional and structural differences in their macromolecules.     

Generalized dynamic model of metal cutting operations

This paper presents a unified mathematical model which allows the prediction of chatter stability for multiple machining operations with defined cutting edges. The normal and friction forces on the rake face are transformed to edge coordinates of the tool. The dynamic forces that contain vibrations between the tool and workpiece are transformed to machine tool coordinates with parameters that are set differently for each cutting operation and tool geometry. It is shown that the chatter stability can be predicted simultaneously for multiple cutting operations. The application of the model to single-point turning and multi-point milling is demonstrated with experimental results.