EFFECTS OF VARIOUS INGREDIENTS ON THE TEXTURE OF MILK JELLY

Effects of various ingredients on the texture of milk jellies prepared from gellan gum, milk powder, sweetener were examined using a sensory test and physical measuring apparatus. The data were analyzed by use of the modification ofScheffé's mixture experiment method in rectangular experimental area in the Scheffé's triangle. "Hardness" and "smoothness" of milk jellies estimated by a subjective method were influenced by the content of gellan gum. The evaluations of "milk flavor" and "sweetness" estimated by a subjective method were varied with the content of sweetener and evaluated as higher for softer milk jellies. The correlation coefficients between "hardness" estimated by a subjective method and "smoothness", "milk flavor", and "sweetness" estimated by a subjective method were negative.     

Immunoglobulin Separation from Egg Yolk: A Serial Filtration System

A serial filtration system was developed for separating immunoglobulin from egg yolk (IgY). Egg yolk was diluted 10 times with water, adjusted to pH 5.0, frozen, then thawed. The diluted yolk was diafiltered through a hard filter paper at 4-6°C to produce a clear water-soluble fraction (WSF). The WSF was then delipidated by filtering through a hydrophobic membrane filter. Ultrafiltration of delipidated WSF at pH 9.0, at 4-6°C, in the presence of 1.5M NaCl resulted in electrophoretically pure (>90%) IgY with a recovery of about 92%. Advantages of this method are the use of only a few mild chemicals and the potential of developing a continuous process.     

Relationships Between Hydrophobicity and Foaming Characteristics of Food Proteins

Hydrophobocity measured fluorometrically for food proteins and pure proteins using cis-parinaric acid as a hydrophobic probe had significant correlations to foaming capacity when the proteins in solution were unfolded by heating in boiling water in the presence of 1.5% dodecyl sulphate prior to fluorometric measurement. Hydrophobicity measured without unfolding, which had previously shown a significant correlation to emulsification, was not significantly correlated with foaming capacity. Two highly significant regression equations were generated: one included hydrophobicity and dispersibility and the other, hydrophobicity and viscosity as the independent variables. High hydrophobicity and viscosity and moderate dispersibility were associated with optimum foaming capacity. There was a significant negative relationship between foam stability and charge density. Hydrophobicity and viscosity were also important in foam stability.     

DETERMINATION OF REACTION ORDER BY LINEARIZATION AND ITS APPLICATION TO ESTIMATION OF MICHAELIS-MENTON PARAMETERS

A simple Basic program was tested with the aid of mathematical models for its reliability for the determination of reaction orders of chemical and enzymatic reactions. Accurate determination of reaction order in hypothetical models was achieved with 5–10 data points, provided that data were available for approximately 80% completion of the reaction. If the maximum extent of completion of the reaction was 60%, then even 20 data points were insufficient for accurate determination. The procedure was also combined with a linearization method and applied to experimental data for the determination of Michaelis-Menten parameters. Mathematically derived V₀'s (initial velocities) allowed calculation of K_m and V_mx with reduced standard errors.     

A New Mapping Super-Simplex Optimization for Food Product and Process Development

Graphic illustration of response surface is difficult to carry out for cases with more than two factors as the graphs are of higher orders than three dimensions. An approximation was made by dividing the level values of each factor into four groups of equal intervals, and then the response values plotted were linked to each other when all other factor levels were “in the same groups” of experimental conditions, instead of “under the same conditions” in the case of two or three dimensional graphics. When applied to mathematical models, this new mapping simplex optimization significantly (p < 0.01) reduced the number of experiments required for reaching the optimum as compared to the Morgan-Deming simplex optimization. Most experiments on food analysis and processing have been optimized within 25 – 35 iterative experiments depending on the number of factors. Computer-directed optimization in conjunction with the mapping technique followed by a simultaneous shift of factor levels greatly facilitated research supervision.     

Ultrasonication, Lyophilization, Freezing and Storage Effects on Fat Loss during Mechanical Infusion of Expressed Human Milk

Ultrasonic homogenization was extended to situations where expressed human milk needs to be stored before being administered. We investigated whether the effect of ultrasonication would persist during storage in the frozen or lyophilized form. Recovery of fat was higher in ultrasonicated and frozen milk (stored for both 1 and 4 mo), than in milk stored following ultrasonication and lyophilization. The low fat recovery from stored lyophilized milk was increased by ultrasonicating the milk after storage and reconstitution (instead of prior to storage). Protein recovery was virtually complete with both methods.     

Pasteurization Efficiency of a HTST System for Human Milk

An economical, small scale heat processing device was studied for rapid and efficient pasteurization of human milk while preserving immunoglobulins A,G and M. Using a continuous flow HTST milk pasteurizer, human milk inoculated with E. coli (10⁶ CFU/mL) or S. aureus (10⁷ CFU/mL) was heated at 71°C at flow rates of 5.9, 12.3 and 18.9 mL/ min. All conditions completely inactivated both microorganisms and resulted in negative alkaline phosphatase activity indicating complete pasteurization. Heat processing of bovine milk at 71°C, at 5.9 mL/min resulted in retention of 30% of the γ-glutamyl transpeptidase (GGTP) activity. Lower residual activity could therefore indicate overpasteurization. Pasteurization at 71°C for 9.0 sec (12.3 mL/min) resulted in retention of 74% of IgA, 75% IgG, and 68% IgM.     

Separation of Phospholipids from Egg Yolk and Recovery of Water-Soluble Proteins

Lipoprotein and water-soluble proteins were separated from egg yolk with sodium alginate. Ninety-nine percent of the lipids were precipitated and 20% of protein remained in the supernatant by this treatment. SDS-PAGE showed the presence of α-, β-, -γ-livetins in the supernatant. Phospholipids were purified from the precipitated lipoproteins by 95% ethanol extraction, then ZnCl₂ precipitation, and subsequent acetone washing. Phospholipids recovery and purity were 78.5% and 95.9%, respectively. Phospholipids thus purified gave a clear colorless solution in chloroform and were free of triglycerides and cholesterol on TLC plates.