Preparation and characterization of a novel bone graft composite containing bone ash and egg shell powder

Egg shells which were hitherto discarded as wastes were collected, purified and powdered into a particle size in the range of 5–50 μm. A composite bone graft material in cylindrical form was prepared using egg shell powder (ESP), bone ash (BA) and gelatin. These bone grafts were characterized for their FT–IR, TGA, XRD, SEM and mechanical properties. The mechanical studies indicate that the composite having a stoichiometric ratio of BA (3 g) and ESP (7 g) has shown better mechanical properties. X-ray diffraction (XRD) data indicated the crystallographic nature of BA is akin to hydroxyapatite (HA) and both BA and ESP did not lose their crystalline nature when bone grafts were prepared. This revealed that ESP may be used as a component in bone graft utilizing the solid waste from the poultry industry.     

MEASURING RHEOLOGICAL CHARACTERISTICS AND SPREADABILITY OF SOFT FOODS USING A MODIFIED SQUEEZE-FLOW APPARATUS

The rheological characteristics of soft foods such as peanut butter, mayonnaise and margarine were evaluated by the UW Meltmeter, a modified squeezing-flow device, applying a constant load under constant volume and changing area. Sample thickness profiles were measured as a function of time and the yield stress was calculated via a Herschel–Bulkley model as a measure of spreadability. Peanut butter exhibited the highest yield stress value (1.31–1.45 kPa) followed by margarine (0.80 kPa) and mayonnaise (0.31 kPa). Calculated values of biaxial extensional viscosity and consistency coefficient values calculated from the UW Meltmeter data followed the expected trends of relative spreadability of peanut butter, margarine, and mayonnaise. These results show that the UW Meltmeter is a relatively simple and reliable device for measuring yield stress and rheological properties of soft foods.

PRACTICAL APPLICATIONS

A new method has been proposed to measure yield stress of spreadable foods.     

Modelling the effect of demand variations on the performance of a production system

Modelling the effect of demand variations on a production system manufacturing multiple products is discussed. The various system costs involved in the production system, namely set-up cost and inventory cost incurred due to change in demands for the products with respect to products and planning periods are estimated. A statistical modelling is presented for determining the production capacity and inventory level requirement to satisfy the customer to a certain level decided by the management. Two important factors, (i) number of types of products and (ii) multiple planning horizons are considered to identify the costs as well as the production capacity and inventory level requirements. A statistical method, analysis of variance (ANOVA) is used to study the variations in the demands and costs involved. Finally, an example is presented to explain the application and the behaviour of the statistical model.     

SMALL AMPLITUDE OSCILLATORY SHEAR STUDIES ON MOZZARELLA CHEESE PART II. RELAXATION SPECTRUM

The frequency dispersion of dynamic mechanical spectra of a low-moisture, part-skim and a low-fat, part-skim Mozzarella cheese are presented. Small amplitude oscillatory shear measurements within the linear viscoelastic range (0.05% strain) were made over 12 weeks of storage. Proteolysis during storage led to softening of the cheeses and thus decreases in storage (G';) and loss (G") moduli. Master curves (at a reference temperature of40C) were obtained by shifting the temperature-dependent frequency dispersion of storage modulus. There was no significant change in G' after 4 weeks of aging. The variation of relaxation time and viscosity spectrum of both cheeses with age were obtained from the master curves using the generalized Maxwell model and nonlinear regression analysis. With maturation the viscosity distribution of corresponding Maxwell elements shifted towards smaller values, indicating that cheeses become softer and melt more easily.     

Anisotropy in Tensile Properties of Mozzarella Cheese

Effects of sampling direction (parallel or perpendicular to protein fiber orientation), cheese type (low-moisture, part-skim, LMPS and reduced fat, RF) and deformation rate (5 and 25 cm/min) on fracture properties of Mozzarella cheese were determined with tensile tests. The fracture toughness, stress, and strain in the parallel direction were, respectively, 2.8, 2.1 and 1.4 times greater than those in the perpendicular direction. This verified that the Mozzarella cheese had anisotropic tensile properties. A composite-material approach was used to explain the direction-dependent properties. The toughness, stress, and strain values for RF cheese were, respectively, 5.9, 5.4, and 1.3 times those of LMPS cheese. The tensile properties of Mozzarella were also affected by deformation rate.     

EFFECTS of HIGH-PRESSURE APPLICATION ON SUBSEQUENT ATMOSPHERIC SOAKING of CORN

Atmospheric-soaking tests were performed on two varieties of corn samples subjected to a pretreatment of high-pressure soaking at 10.5, 21, and 35 MPa. Soaking tests were also conducted with samples without any pretreatment at different soaking temperatures of 20, 40, 60, and 100C. Increased duration of initial high-pressure soaking was found to reduce the rate of moisture absorption during the subsequent atmospheric soaking. Predicted soaking times required for the samples to reach 45% moisture content increased with increase in applied pressure and with increase in the duration of high-pressure application. Therefore, initial high-pressure application should be limited to a low pressure level and only for a short duration. Compared with the results of the high-temperature soaking tests, initial high-pressure application does help to shorten the steeping time required at atmospheric conditions but not to the extent to compensate for the effect of high temperatures.     

The impact of OPT and TPM on the economic production quantity

In manufacturing systems, the material flow is influenced by a number of factors, such as batching policies, capacity of machines, machine breakdowns, etc. Realizing the role of batching policies and reliability of machines in production systems, a mathematical model is presented here for determining optimal batching policies with the objective of improving the speed of material flow considering machine breakdowns and batch splitting and forming. This model is employed for studying (i) the significance of total preventive maintenance (TPM); (ii) the use of the optimized production technology (OPT) concept in batching policies; and (iii) the influence of a set-up cost reduction programme on the performance of manufacturing systems. The basic criterion considered for optimizing the batch sizes is the minimization of total system cost (TSC). An example problem is solved to explain the application of the model.     

MILK COAGULATION CUT-TIME DETERMINATION USING ULTRASONICS

A nondestructive method of determining milk coagulation cut-time was investigated. Velocity and attenuation of ultrasonic waves through coagulating skim milk were measured after rennet addition. the ultrasonic attenuation measurements were found suitable for distinguishing the effect of different experimental variables (three levels of temperature, rennet and CaCl₂). Based on the rate of change of attenuation during coagulation, a turning point was defined at which the attenuation rate change was -0.1 neper/m/min. the cut-time was proposed to be 20 min from the time the turning point was observed. the cut-times predicted by this criterion were statistically similar to those predicted by the manual method currently used in the industry.