Starch/Solute Interaction in Water Sorption as Affected by Pretreatment

The effect of the freeze-drying process on the structure of starch and starch-sucrose mixtures was studied. The technique of inverse gas chromatography was used to study the interaction between organic compounds (probes) and starch (hylon 7) as well as starch-sucrose mixtures. The structural and morphological characteristics of the starch-solute mixtures from the thermodynamic parameters of these interactions was also examined. The porous freeze-dried samples interacted more with certain organic probes compared with untreated starch as indicated by higher values of specific retention volumes (Vg_o). Untreated starch apparently interacted only on the surface with organic probes. Freeze-dried starch reacted only with polar organic probes, particularly those with hydrogen bonding propensity. Cluster analysis of the water sorption isotherms correlated with data obtained from the injected probes.     

Starch/Sucrose Interactions by Organic Probe Analysis: An Inverse Gas Chromatography Study

The effect of freeze drying of high amylopectin starch was determined with samples of starch dispersed in water with or without solubilized sucrose. The X-ray diffraction data showed that this treatment disrupted crystalline structures of amylopectin and sucrose exposing additional sites for water sorption. This was shown also by sorption isotherms of the starch alone. The Hylon 7-sucrose freeze-dried samples produced a greater effect on sorption than did the corresponding Amioca freeze-dried mixtures. Organic probe analysis of the starch and starch-sucrose mixtures indicated that high amylose starches were more reactive with polar organic probes than high amylopectin starches when freeze-dried. Untreated high amylopectin starches were more reactive with probes in agreement with the water sorption data for a more branched polymer.     

Effect of Tomato Paste on Rheological Properties and Particle Size Distribution of Model Oil-in-Water Emulsions

The role of tomato paste in stabilizing model o/w salad dressing formulations pre-stabilized with xanthan and propylene glycol alginate was studied at levels of tomato paste ranging from 3 to 12% using creep measurements, steady shear measurements and particle size measurements. The addition of tomato paste shifted the particle size distribution to lower values; this distribution was a function of aging time. Creep and steady shear measurements showed an increase in rheological parameters and an increase in viscosity, respectively, suggesting that at higher or equal levels of 6% tomato paste the stability of the o/w emulsion was enhanced significantly.     

Protein composition of milk from Holstein–Friesian dairy cows and its relationship with the genetic variants A and B of κ-casein and β-lactoglobulin (Part I)

The protein composition and the milk yield (morning milking) were studied in 10 Chilean Holstein–Friesian first lactation dairy cows during the spring season. In addition, the genetic variants A and B of κ-casein (κ-CN) and β-lactoglobulin (β-Lg) were also identified. The results showed that the casein content is significantly affected by the presence of B variant of κ-CN. Moreover, positive interactions between the B variant of κ-CN with AB of β-Lg and the combination of A κ-CN with AA of β-Lg for the total protein content, were found.     

Effect of Egg Yolk and Egg Yolk + Salt on Rheological Properties and Particle Size Distribution of Model Oil-in- Water Salad Dressing Emulsions

The role of egg yolk and egg yolk + salt in stabilizing oil-in-water (o/w) salad dressing emulsions pre-stabilized with xanthan and propylene glycol alginate was studied using creep tests, steady shear, and particle size analysis. Results show that each combination significantly affects rheological stability of model o/w salad dressing emulsions. All emulsions exhibited viscoelasticity and wcrc characterized by three parameters: η₁, E₁ and η_N. Steady shear measurements showed that both egg yolk and salt increased viscosity radically. Particle size data showed significant changes with both addition of egg yolk and salt to the model system.     

Effect of Propylene Glycol Alginate and Xanthan Gum on Stability of O/W Emulsions

The role of xanthan gum and propylene glycol alginate in stabilizing model oil-in-water salad dressing emulsions has been studied using rheological measurements, particle size analysis and surface tension. Increasing xanthan gum concentration within the gum ratio gave higher viscosity due to formation of aggregates with larger sizes. Propylene glycol alginate (PGA) was surface-active leading to reduction in surface tension of air/water surfaces. Reduction in viscosity was seen in the presence of PGA.     

β-Robust scheduling for single-machine systems with uncertain processing times

In scheduling environments with processing time uncertainty, system performance is determined by both the sequence in which jobs are ordered and the actual processing times of jobs. For these situations, the risk of achieving substandard system performance can be an important measure of scheduling effectiveness. To hedge this risk requires an explicit consideration of both the mean and the variance of system performance associated with alternative schedules, and motivates a β-robustness objective to capture the likelihood that a schedule yields actual performance no worse than a given target level. In this paper we focus on β-robust scheduling issues in single-stage production environments with uncertain processing times. We define a general β-robust scheduling objective, formulate the β-robust scheduling problem that results when job processing times are independent random variables and the performance measure of interest is the total flow time across all jobs, establish problem complexity, and develop exact and heuristic solution approaches. We then extend the 0-robust scheduling model to consider situations where the uncertainty associated with individual job processing times can be selectively controlled through resource allocation. Computational results are reported to demonstrate the efficiency and effectiveness of the solution procedures.     

Relationship between A and B variants of κ-casein and β-lactoglobulin and coagulation properties of milk (Part II)

The purpose of this study was to relate the genetic variants A and B of κ-casein (κ-CN) and β-lactoglobulin (β-Lg) of the milk of 10 Chilean Holstein–Friesian cows and its coagulation properties (coagulation ability of milk, curd firmness and syneresis of the curd).
The results showed that β-Lg AB phenotypes have a significant effect on the studied properties in comparison with the samples containing the AA phenotype. A and B variants of κ-CN did not have a significant effect on the coagulation properties, although there was a favourable interaction between β-Lg AB and κ-CN B.