Stability of Glutamic Acid and Monosodium Glutamate Under Model System Conditions: Influence of Physical and Technological Factors

The stability of glutamic acid and monosodium glutamate as regards pH, temperature and oxygen was studied during storage and two thermal processings, the residual products and those which appeared being determined. The initial molecules only change into pyrrolidonecarboxylic acid, never into glutamine nor γ-aminobutyric acid. Preservation is good in all cases at pH 0 and pH 14, but glutamic acid is converted to pyrrolidonecarboxylic acid at intermediate pH values. The change is favored by pH values ranging from 2 - 3, by temperature increase and by oxygen.     

Milling and Processing of Wheat and other Cereals Affect Their Capacity to Inhibit Pancreatic Lipase in Vitro

The inhibition of pancreatic lipase activity by extracts of raw, milled or processed cereals was measured in vitro. The inhibitory activity was high in durum wheat, soft wheat and millet, moderate in barley and white sorghum and very low in red sorghum. Milling whole-grain into flours markedly decreased the lipase inhibitory activity in all species. In durum wheat, the germ and the aleurone-layer fraction exhibited the highest inhibitory activity. Processing of soft wheat by bread making, popping, flaking, drum-drying and extrusion-cooking, or durum wheat by making pasta markedly decreased the lipase inhibitory capacity. Extractible proteins were implicated in the inhibition process. These effects also had some nutritional implications.     

Fractionation of Anhydrous Milk Fat by Superficial Carbon Dioxide

Milk fat was fractionated with supercritical CO₂ (SC-CO₂) into 8 fractions at temperatures of 50° and 7O°C, over a pressure range of 100–350 bar. Two fractions (L1 and 2) were liquid, 3 fractions (11–3) were semi-solid and 3 fractions (Sl-3) were solid at 20°C. The peak melting temperature progressively increased (9.7° to 38.3°C) from fraction L1 to S3. The concentration of short chain (C24-C34) triglycerides decreased from fraction L1 to S3 while that of long chain (C42-C54) triglycerides increased gradually. The medium chain triglycerides were more concentrated in fractions L2 and 11–3. The proportion of short (C4-C8) and medium (ClO-C12) chain fatty acids decreased and that of long (C14-C18) chain fatty acids increased gradually from fraction Ll-S3. The weight average molecular weights and geometric mean-carbon number of milk fat fractions were in the range from 625.6 to 805.0 and 34.2 to 47.6, respectively, in comparison to 729.3 and 41.O, respectively, for native milk fat, suggesting SC-CO₂ effected a fair degree of molecular weight separation.     

Objective and Subjective Texture Evaluation of Irradiation Sterilized Meat Products

Instrumental measures of textural properties and texture panel evaluations were obtained on several meat products irradiated using various dose-temperature conditions. Both the panel results and the instrumental data revealed several irradiation treatments that produced a tougher meat than the nonirradiated controls. Further studies indicated this toughening was due to a freezing-irradiation interaction.     

Factors Affecting the Acceptability of Low-Nitrite Smoked, Cured Ham

Two experiments were conducted to evaluate the consumer acceptance of samples of cooked, smoked ham which varied in sodium nitrite concentration and to evaluate the importance of two factors hypothesized to affect their acceptability. The first experiment assessed the importance of color to the overall acceptability of smoked ham. Results indicated that satisfactory color in this product can significantly increase its acceptability, even when other attributes (e.g. flavor) of the product are inferior. The second experiment assessed the effect of a warning of the possible dangers of sodium nitrite on the acceptability of the products. Results showed that the warning had no effect on the consumers' acceptance of the product.     

Role of Consumer Expectancies in the Acceptance of Novel Foods

Six experiments were conducted to examine factors affecting the consumer acceptance of novel foods. Variables included for analyses of their effects were: (1) preparation variables; (2) product name and type of serving vessel; (3) brand labels and packaging; (4) availability of product information; (5) nature and quantity of product information; and (6) degree of familiarity of the user with the product. Results of these experiments were interpreted within a theoretical framework that postulates that the hedonic response to food is a function of the degree to which expectancies about the food are matched by subsequent experiences with it. Based on the theory of cognitive dissonance, this theoretical framework is proposed as a useful analytic tool for predicting consumer responses to novel foods.     

CELLULARITY, MECHANICAL FAILURE, AND TEXTURAL PERCEPTION OF CORN MEAL EXTRUDATES

Relationships among cellular structure, fracturability, and sensory properties in porous, brittle extrudates were investigated. Corn-based extrudates intentionally processed to exhibit a range of physical structures were characterized in terms of cell size distribution, bulk density, mechanical strength, fracturability, and sensory attributes. These measurements show both mechanical strength, defined by average compressive stress during extended deformation, and fracturability, quantified by fractal and Fourier analyses of stress-strain functions, increasing with either decreasing mean cell size or increasing bulk density. Fracturability parameters or structural characteristics are furthermore correlated with sensory scores for crunchiness, crispness, hardness and perceived density. These results indicate that cellularity strongly influences the pattern of mechanical failure and that failure characteristics, such as fractal dimension or power spectrum of stress-strain functions, are reflective of sensory texture.     

EFFECTS OF SOY PARTICLE SIZE AND COLOR ON THE SENSORY PROPERTIES OF GROUND BEEF PATTIES

A study was conducted to assess the effect of both size and color of textured soy protein particles on the visual and textural properties of extended (20% replacement) ground beef patties. A trained texture profile panel judged the hardness, cohesiveness, chewiness, moistness, and oiliness of nine different samples. In addition, judgments of the visual attributes of darkness, size of particles, and density of particles were made. Significant effects of soy ingredient were found for all judged attributes. It was concluded that soy ingredients having particle sizes smaller than the diameter of the openings of the grind plate used to process the meat/soy mixture produced the greatest change in the texture of the ground beef patties, because these particles passed through the grind plate unscathed, producing an easily discernable matrix of large meat particles and small soy particles. It was also concluded that carmel-colored soy ingredients produced less lightening of the cooked samples than uncolored soy ingredients.