Stability of Membrane-Sterilized Bovine Immunoglobulins Aseptically Added to UHT Milk

Lyophilized immunoglobulin (IgG) of 56% purity isolated from Cheddar cheese whey was reconstituted with distilled water to a protein content of 60–70 mg/mL. The solution was membrane-sterilized (0.2 μ.m) and aseptically injected into cartons of UHT milk. This method could be used for fortification of UHT products without denaturing IgG. Concentration of IgG remained constant in milk stored at 4, 25 and 35°C over 5 mo. However, when stored at 25 and 35°C, the milk thinned probably due to residual enzymes in the IgG solution. D values measured between 62 and 80°C for thermal destruction of IgG in UHT milk appeared to confirm shelf life results.     

Computer-aided Optimization of Wine Blending

An objective method was developed to blend wines for standardizing flavor quality. Aroma volatiles of varietal and white stock wines, and the target wine were analyzed by equilibrium gas headspace chromatography. Similarity of the aroma profiles of the varietal and stock wines to the target wine was calculated from GC peak areas. The simplex optimization program carried out computational bleeding to determine the ratios of the varietal and white stock wines that would be required to simulate the aroma of the target wine. For two blending experiments, the computer optimized blend could not be differentiated from target wine by a sensory taste panel.     

EFFECTS OF GELLAN GUM, CITRIC ACID AND SWEETENER ON THE TEXTURE OF LEMON JELLY

Effects of various ingredients on the texture of lemon jellies prepared from gellan gum, citric acid and sweetener were investigated by rheological measurement and sensory evaluation. The data were analyzed by use of the modification of Scheffé's mixture experiment method in converse triangle experiment area. The contours of the response surface were drawn using the best model whose terms were searched by AIC statistic, and the approximate model was calculated to consider the contours. "Hardness" estimated by both methods was large in jellies with high content of gellan gum and low content of citric acid. The content of citric acid significantly influenced "smoothness" estimated by a subjective method. The influence of citric acid varied with the content of gellan gum. The correlation coefficients of evaluation between "hardness" and "lemon flavor" or "sourness" were negative.     

Reduction of BetaLactoglobulin Content of Cheese Whey by Polyphosphate Precipitation

When cheddar cheese whey was treated under the optimized conditions, i.e., 1.33 mg/mL sodium hexametaphosphate (SHMP) at pH 4.07 and 22°C for 1 hr, more than 80% of β-lactoglobulin was removed by precipitation. In the supernatant, almost all of the immunoglobulins and the major portion of α-lactalbumin were retained, as indicated by SDS gel electrophoresis. Immunochemical assays showed that approximately 90% of immunoglobulin G activity was found in the supernatant. By dialysis against water for 48 hr, 72.2% and 45.3% phosphorous was removed from the supernatant and precipitate, respectively.     

Reverse-Phase HPLC Analysis of Reference Cheddar Cheese Samples for Assessing Accelerated Cheese Ripening

Applying water extracts from Cheddar cheese to an octadecyl vinyl alcohol copolymer column using a reliable auto-sampling system provided highly repeatable HPLC patterns. Two batches of standard samples of mild, medium, sharp, and extra-sharp and one batch of abused samples (rapidly aged under abnormal conditions) were analyzed. Principal component similarity (PCS) analysis indicated similar shifts of plots due to aging of the standard batches, while the plot for the abused batch deviated from the pathway of normal aging. PCS may be useful for analysis of accelerated ripening effects as well as finding unusual samples during quality control.     

Standardization of Mapping Simplex Optimization

Although the mapping process significantly improved the efficiency of simplex optimization, the procedure subsequent to mapping required manual adjustments. An attempt was made to standardize the optimization procedure so as to avoid subjectivity. A selfinstructive computer program of the standardized procedure was written for a hand-held computer. The program was inexpensive and convenient to apply the mapping simplex optimization to problems in product and process development.     

Ingredient Interaction Effects on Protein Functionality: Mixture Design Approach

A ten-point augmented simplex-centroid design was used to study the effects of ingredient interactions on properties of food protein mixtures. Hydrophobicity, solubility and functional properties (emulsifi-cation and color) of three ingredients (bovine casein and salt-extractable proteins from chicken breast muscle and beef heart) as well as mixtures of the ingredients were tested. Significant deviations were observed between experimentally measured properties of mixtures and values calculated assuming linear addition of individual ingredient properties. Regression models including significant interaction terms were calculated for ingredient-hydrophobicity and ingredient-functionality relationships, and used in computerized optimization of two hypothetical formulations.     

Relationships of Hydrophobicity and Net Charge to the Solubility of Milk and Soy Proteins

Protein hydrophobicity of 42 native and partially denatured milk and soy protein samples was determined fluorometrically by using three probes, 1-anilino-8-naphthalenesulfonate (ANS), cis-parinarate (CPA) and 1,6-diphenyl hexatriene (DPH), and chromatographically by using Phenyl Sepharose CL-4B (PSC). PSC and ANS hydro- phobicities correlated well to the protein insolubility determined at zero zeta potential, whereas no significant correlation was observed between CPA. hydrophobicity and protein insolubility. When backwards stepwise regression analysis was applied to 189 data of protein insolubility, a significant correlation (P < 0.001) was obtained between PSC hydrophobicity, zeta potential and protein insolubility. It is suggested that the aromatic hydrophobicity, in conjunction with zeta potential, may play a more important role in protein solublity than the aliphatic hydrophobicity.