ABSTRACT
The starch granules of both Purity W, a modified waxy cornstarch, and wheat flour were affected by processing, refrigeration, freezing, and reheating. The major change in starch granules shown by scanning electron micrographs was the trend towards greater deformation of the starch granule and, apparently, subsequent greater homogeneity of the mixture. Sensory evaluation revealed a statistically significant difference (p of less than 0.05) only in overall acceptability of the fresh vs. the frozen soup. The other quality characteristics of texture acceptability, consistency, and syneresis were not statistically (p of less than 0.05) different.
Subject(s)
Flour , Food Preservation , Food Technology , Frozen Foods , Starch , Evaluation Studies as Topic , Female , Hot Temperature , HumansABSTRACT
In this study, evaluation of scanning electron micrographs emphasized that a heated starch-water dispersion is sensitive not only because of the type of starch but also to the mode of heating, cooling, and reheating. Differences in granule appearance were seen with both corn and wheat starch-water dispersions when they were heated at different rates. Both freezing and reheating influenced the starch-water dispersions. Microwave oven reheating appeared to yield a product with more retrogradation of the starch component. For an understanding of the effect of temperature-time stresses on this common ingredient, starch, much more study is needed.
Subject(s)
Freezing , Hot Temperature , Starch , Microscopy, Electron, Scanning , Triticum , Zea maysABSTRACT
The similarities and differences between raw starches and heated starch-water dispersions were determined pictorially using a scanning electron microscope. The photomicrographs showed that raw unmodified starches ranged from small and round to large and ellipsoidal in shape, with variation in uniformity and smoothness of the surface. Heating of corn and wheat starch in water dispersions caused swelling of the starch granule, some exudate, and eventual loss of original granule integrity. The scanning electron microscope is a sensitive, useful tool to evaluate changes which occur in starch systems.
Subject(s)
Starch , Amylopectin , Amylose , Hot Temperature , Microscopy, Electron, Scanning , Oryza , Triticum , Vegetables , Zea maysABSTRACT
Safety and economics concerns have accentuated an interest in energy input and consumption in the foods industry. This review article focuses on reported temperatures and temperature histories in food preparation and processing. To assist in interpreting reported data, a basic understanding of heat transfer parameters used is given. The relationships between temperature and time histories and quality effects of physical and chemical changes in foods, the production of new compounds with possible health effects, and microbiological safety are summarized. Several areas of needed research are identified.
Subject(s)
Food Handling , Food , Temperature , Animals , Bread , Calorimetry, Differential Scanning , Cattle , Chemical Phenomena , Chemistry, Physical , Cooking , Eggs , Fishes , Food/standards , Fruit , Hot Temperature , Meat , Poultry , Swine , Thermal Conductivity , Thermodynamics , Thermography , Thermogravimetry , VegetablesABSTRACT
A computer model and instructional material provide the student with the opportunity to learn basic information and gain expertise in solving problems which occur in foods. The model covers twenty-five simulations over a range of food types, permitting a variety of experiments of differing complexity. The student is assigned a problem or activity which may be partially or completely answered by using one of the simulations. The simulations give answers to a series of treatments and tests, properties, recipes, characteristics, and/or sensory parameters being investigated.
Subject(s)
Computer-Assisted Instruction/methods , Food , Nutritional Sciences/education , Humans , Problem SolvingABSTRACT
Evidence obtained in this study indicates that computer simulations can be a successful method of teaching foods or can replace laboratory experiences. For nine of eleven attitudinal test items, students' attitudes became more positive concerning the value of the course in which computer simulations were used. On the achievement test, seventeen of the twenty-five questions revealed that significant learning (p of less than or equal to 0.05) occurred when the simulations were integrated into a foods course. These students seemed to do well and to like this method of instruction. The advantages of these computer simulations are that students can be motivated to learn and solve problems.
Subject(s)
Computer-Assisted Instruction/methods , Food , Nutritional Sciences/education , Humans , Problem SolvingABSTRACT
Pressurisation of pre-rigor muscles produced very firm meat in muscles which had contracted to as little as 48% of their on-carcass length. Immediate post-treatment pH was 5·81, significantly lower than the controls; however, there was no significant difference at 24 h. Water holding capacity of the treated samples was significantly lower and weep significantly higher than the controls. However, cooking losses for the treated samples were lower, resulting in an over-all loss which was not different between control and treated samples. Warner-Bratzler shear tests and taste panel evaluations indicate a highly significant improvement in tenderness. Scanning electron micrographs show an extensive disruption of the sarcolemma.