Experimental Assessment of Pore Breakaway During Sintering

Experimental measurements of intragranular pore-size distributions and of the shapes of distorted pores attached to grain boundaries were used to examine the podgrain-boundary separation problem. In situ evaluation of the ratio of the boundary mobility-to-surface diffusivity from pore distortion measurements, coupled with prior analytic expressions for the critical pore breakaway condition, permitted specific intragranular pore sizes generated by separation to be predicted. The predictions lie within the distribution of measured intragranular pore sizes.     

Effect of hydrogen peroxide treatment on the quality of raw cream

The effect of hydrogen peroxide on the attributes of raw cream was studied. The samples with 500 mg/kg and 1500 mg/kg hydrogen peroxide (H₂O₂) were compared with an untreated control sample. The results indicated that the addition of hydrogen peroxide prevented, to a great extent, the development of lipolysis, proteolysis and acidity, as well as the growth of psychrotrophic microorganisms. However, the treatment had a negative effect on the oxidative stability of the cream.     

PEELING AND THE PHYSICAL AND CHEMICAL PROPERTIES OF KIWI FRUIT

Hand peeling of kiwi fruit has some disadvantages such as difficulty during peeling, increase of loss in weight and nutritional value. Peeling of kiwi fruits with alkali (NaOH) was investigated. Some chemical (acidity, pectin, and chlorophyll) and physical properties (Hunter color value and weight loss) of the fruits were determined after selected alkali peeling methods were used. Peeling methods at 80, 90 or 100C temperatures; in 13, 18 or 23% of NaOH solutions and for 3, 4 or 5 min durations were tested and compared with hand peeling. Weight (fruit tissue) loss in hand peeling was higher than alkali peeling. Peeling with alkali was easier. Nutritional value (ascorbic acid content) of alkali peeled fruits was higher than hand peeled kiwi fruit. Because of less weight loss, better green color and high pectin content the method including 15% of NaOH solution at 95C for 4 min was selected as most advantageous peeling method.     

Partial characterisation of enterocin KP produced by Enterococcus faecalis KP,a cheese isolate

Enterococcus faecalis KP, a bacteriocin‐producing strain, was identified using 16S rRNA gene sequence homology (99%). Enterocin KP from E. faecalis KP was sensitive to papain and ß‐mercaptoethanol, but resistant to trypsin, pepsin, lipase, catalase, α‐amylase, organic solvents, detergents, EDTA and heat treatment (90°C/30 min). It was active at a wide pH range (2.0–8.0) and produced at maximum level in de Mann Rogosa Sharpe broth at 32°C with an inoculum amount of 0.1–1.0% and an initial pH of 5.5–7.5. It was active against some Gram‐positive bacteria, including Listeria monocytogenes. It showed bactericidal activity against L. monocytogenes and its molecular weight was approximately 5.8 kDa.     

A calculation method of cracking moment for the high strength concrete beams under pure torsion

In this study, a method is given to calculate cracking moments of high strength reinforced concrete beams under the effect of pure torsion. To determine the method, both elastic and plastic theories were used. In this method, dimensions of beam cross-section were considered besides stirrup and longitudinal reinforcements. Two plain high strength concrete (without reinforcement) and eight high strength reinforced concrete beams which have two different cross-sections (150 × 250 mm and 150 × 300 mm) were produced to examine the validity of the proposed method. The predictions of the proposed approach for the calculation of the cracking moment of beams under pure torsion were compared with the experimental and the analytical results of previous studies. From these comparisons it is concluded that the predictions of the proposed equations for the cracking moment of plain and reinforced high strength concrete beams under pure torsion are closer to the experimental data compared to the analytical results of previous theories.     

Thermal resistance of aerobic spore formers isolated from food products

The heat resistance of aerobic spore formers isolated from dairy products and cocoa powder was examined to give an overview of occurring highly heat‐resistant spores. Experiments were conducted in phosphate buffer at different temperatures for 30 min. Two Geobacillus pallidus strains survived the heat treatment at 125 °C with log reductions of 6.68 and 6.73. Furthermore, the inactivation kinetics of one of these strains (Bacillus amyloliquefaciens) were determined using a modified Arrhenius model. The inactivation followed a reaction order of 1 with a reaction rate constant (k_ref) of 0.085/s at 394 K and an activation energy (E_a) of 209 kJ/mol.     

CHANGES IN Pb, Cd, Fe, Cu AND Zn LEVELS DURING THE PRODUCTION OF KAŞAR CHEESE

ABSTRACT

Levels of Pb, Cd, Fe, Cu and Zn in milk, curd, pressed curd, fresh cheese, whey, rennet and scalding water taken from two different Ka?ar cheese plants (A and B) in Ankara, Turkey were investigated. The milk used in plant A contained higher amount of Pb, Fe and Zn than the milk used in plant B. Pb level during processing in both dairy plants showed a significant increase from milk to curd (626.2–912.3 µg/kg for plant A and 265.2–371.8 µg/kg, dry weight, for plant B) (P < 0.01). Similarly, Fe, Cu and Zn contents of the curds in plant A and B showed an important increase with respect to the milk (P < 0.01). During transition of the curd to pressed curd and of pressed curd to fresh cheese, almost all metals tested showed a decrease because of the loss of these metals into whey and scalding water. The results showed that curdling the milk was the most important contamination step.

PRACTICAL APPLICATIONS

Heavy metals may enter the human body through food, water, air or absorption through the skin, and can cause metabolic anormalies. Heavy metals may reach our foods from a number of sources. The more important of these are: soil; the chemicals applied to agricultural land; the water used in food processing or cooking; and the equipment, containers and utensils used for food processing, storage or cooking. Milk and milk products are the basic components of the human diet, and among milk products cheese holds an important place. Ka?ar cheese ranks second with respect to consumption, significantly contributing to the Turkish diet. In order to prevent the health risk of consuming contaminated cheeses, it is very important to determine the effect of equipment and process variation on the heavy‐metal content of Ka?ar cheese. The results of this study would help the regulatory authorities to establish a Hazard Analysis and Critical Control Points (HACCP) plan and to identify important contamination sources for Ka?ar and similar kind of cheeses.

     

EFFECTS OF BIFIDOCIN B AND LACTOCOCCIN R ON THE GROWTH OF LISTERIA MONOCYTOGENES AND BACILLUS CEREUS ON STERILE CHICKEN BREAST

In the study, the efficacies of bifidocin B and lactococcin R produced by Bifidobacterium bifidum and Lactococcus lactis subsp. cremoris R to control Listeria monocytogenes or Bacillus cereus in irradiated raw chicken breast during storage at 5–8C for 28 days or at 22–25C for 24 h were determined. Each irradiated raw chicken breast was inoculated with 10⁶ cfu/g L. monocytogenes or B. cereus. It was found that both bacteriocins were more effective against L. monocytogenes or B. cereus at 5–8C than at 22–25C, and that lactococcin R was more inhibitory than bifidocin B. Challenge study analysis demonstrated that incorporation of bifidocin B or lactococcin R at a level of 1,600 or 3,200 AU/g could effectively inhibit the growth of L. monocytogenes or B. cereus for 3–4 weeks at 5–8C or 6–12 h at 22–25C.