MECHANICAL PROPERTIES OF A CORN STARCH PRODUCT DURING THE POST-FRYING PERIOD

The mechanical properties of the crust and core regions of an immersion-fried corn starch patty containing different amounts of gluten, amylose, and amylopectin were studied after various storage times. Moisture and oil profiles for the different gluten contents were also determined during post-frying storage. The addition of gluten did not affect the hardness of the crust region of the fried samples during storage, but the addition of amylose and amylopectin significantly increased the hardness of the crust. Samples with 5% added amylopectin showed a similar behavior, but in this case the puncture force significantly increased during the first hour of storage and remained constant thereafter. The range of linear viscoelastic behavior for fried corn starch patties in compression was for strains up to 4%. Stress relaxation curves showed that the elasticity of corn starch patties increased with time of storage, but decreased with the addition of gluten. The addition of 5% amylose caused a significant increase in elasticity, whereas with 5% amylopectin, the increase in this variable was less noticeable.     

AMINO ACID COMPOSITION OF SOME BRAZILIAN SEAWEED SPECIES

Fourteen common seaweed species from northeastern Brazil were examined for protein content and amino acid composition. Protein content varied greatly among the species, ranging from 2.30% (dry weight basis) in Corallina offlcinalis to 25.60%, in Amansia multifida. The species Amansia multifida, Caulerpa sertularioides. Enantiocladia dupcrreyi, Solieria filiformis and Vidalia obtusiloba had protein levels comparable to those of many edible legume seeds, above 18%. They showed high levels of acidic amino acids and reasonable levels of essential amino acids, with methionine being the first limiting amino acid for most of the species. The exceptions were Sargassum vulgare that had a very high content of methionine and Caulerpa sertularioides in which lysine is the first limiting amino acid and methionine the second limiting one. All species are rich in phenylalanine/tyrosine and threonine, and six are very good sources of lysine. The potential use of these species as food and/or feed is discussed .     

CONTINUOUS PASTEURIZATION OF EGG YOLK: THERMOPHYSICAL PROPERTIES AND PROCESS SIMULATION

This article presents empirical correlations to predict the density, specific heat, thermal conductivity and rheological power–law parameters of liquid egg yolk over a temperature range compatible with its industrial thermal processing (0–61C). Moreover, a mathematical model for a pasteurizer that takes into account the spatial variation of the overall heat transfer coefficient throughout the plate heat exchanger is presented, as are two of its simplified forms. The obtained correlations of thermophysical properties are applied for the simulation of the egg yolk pasteurization, and the obtained temperature profiles are used for evaluating the extent of thermal inactivation. A detailed simulation example shows that there is a considerable deviation between the designed level of heat treatment and that this is predicted through process simulation. It is shown that a reliable mathematical model, combined with specialized thermophysical property correlations, provide a more accurate design of the pasteurization equipment that ensures effective inactivation, while preserving nutritional and sensorial characteristics.     

A Method for the Analysis of Tyramine in Meat Products: Its Content in Some Spanish Samples

A method is described for the analysis of tyramine in meat and meat products by sand column extraction eluted with ethyl acetate. Tyramine is determined quantitatively by fluorometry once the corresponding fluorophore has been formed by reacting the final extract with α-nitrous-β-naphthol Qualitative confirmation is carried out by spectrofluorometry and thin-layer chromatography. The average recovery was 88.80% and the relative standard deviation 6.35%. The method has been applied to 15 Spanish meat products, the amounts found oscillating between 0.13 and 301.2     

TRAINING A SENSORY TEXTURE PROFILE PANEL AND DEVELOPMENT OF STANDARD RATING SCALES IN COLOMBIA

Two texture profile panels and two panel leaders were trained in the General Foods Sensory Texture Profiling Technique in Colombia using Colombian foods as reference points on the standard rating scales. The texture profiling technique adapted to Colombian conditions very successfully. The trained texture profile panel is now playing an essential part in the development of protein-fortified staple foods of acceptable textural quality for Colombia.     

A RESEARCH NOTE: STUDY ON THE QUALITY OF PACHARÁN BY SENSORY EVALUATION

Pachardn is a traditional drink of Navarra, Spain. This spirit is an alcoholic drink which ranges from intense pink to red in color and whose base is sloe (Primus spinosa, L.) flavored with, the essential oils of aniseed and sugar. Sensory analysis was performed using samples from twenty-one different brands of commercial pachardn. Statistical techniques employed were formations of a linear correlation matrix, followed by factor analysis and multiple linear regression. Factor analysis permitted reduction of the sensory variables examined (color, aroma quality, flavor quality, sweetness, acidity and overall impression) to two factor variables (“flavor and aroma” and “color”). The position of the brands with respect to these two factors indicate the necessary changes to improve pachardn quality. The factors “flavor and aroma” had the chief direct effect on Overall Impression.     

RHEOLOGICAL PROPERTIES AND FLUID DYNAMICS OF COFFEE EXTRACT

The rheological behavior of coffee extract with different water contents (49 to 90%) was studied at a wide range of temperatures (274 to 365 K) using a concentric cylinder rheometer. The flow curves followed different models depending on the concentration and temperature level. Newtonian behavior was observed at high values of water content and temperature, changing to power law as these values were decreased. The Newtonian viscosity as well as the consistency and behavior index could be well correlated by functions simultaneously dependent on temperature and water content. The rheological parameters, together with experimental values of pressure loss in tube flow, were used to calculate friction factors. These showed to be in good agreement with those resulting from classical theoretical and empirical equations, thus confirming the reliability of the rheological measurements.     

MOISTURE MIGRATION IN A POTATO STARCH PATTY DURING POST-FRYING PERIOD

The change in crispness of the crust region of a fried food due to water migration was studied duringfrving and post-frying period. Moisture distribution was determined immediately after frying and at different times during storage. A restructured starch system consisting of potato starch and distilled water 16 was prepared in the shape of a patty. the moisture distribution in the patty was determined during fiying and post-frying period. Experiments were conducted for two dfferent flying times, 10 and 20 mm, using an oil temperature of 180G. Moisture distribution also was determined in patties fried for 10 mm and stored at 4C in a sealed container for 0.5, 3, and 4.5 h.
The experimental moisture profiles were compared with those obtained with a mathematical model, based on the one-dimensional heat and mass transfer in the core and crust regions of an infinite slab. Changes in the moisture content were correlated with changes in the mechanical properties of the crust during storage.