Biomedical subjects
F M Clydesdale
Publications and source records attributed to F M Clydesdale.
Research issues and needs for the future.
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Fortified vs natural foods: the debate continues.
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Optimizing the diet with whole grains.
Dietary recommendations may be perceived by the general population as causing a shift to less food and perhaps to less aesthetically pleasing foods often resulting in noncompliance. Technology can play a key role in this scenario by creating new formulated foods as well as by utilizing technology to modify whole foods or foods containing whole foods and enhancing both their health benefits and acceptability. At present we have evidence for a positive role in health of nutrients and many nonnutrients in foods, such as whole grains. However, all the linkages between dietary components and disease are not clear. Therefore, it is critical to design not only appealing formulated foods, but to also ensure adequate consumption of whole foods in order to obtain those compounds we know to be linked to good health, as well as those yet-unknown compounds or interactions in food that are also linked to good health. In all cases, the technical and functional properties of food, as well as the nutritional, must be considered in order to optimize acceptability and assist in achieving compliance in meeting dietary recommendations.
Changes in color and flavor and their effect on sensory perception in the elderly.
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Color as a factor in food choice.
From birth, nature teaches us to make judgements on our environment based in large measure on color. As such, it plays a key role in food choice by influencing taste thresholds, sweetness perception, food preference, pleasantness, and acceptability. Its role is elusive and difficult to quantify, however, which at times has placed color in a secondary role to the other sensory characteristics, a position not entirely consistent with the facts. Color, in a quantitative sense, has been shown to be able to replace sugar and still maintain sweetness perception in flavored foods. It interferes with judgments of flavor intensity and identification and in so doing has been shown to dramatically influence the pleasantness and acceptability of foods. Studies in the literature have used cross-sectional population panels to study these effects, but a recent investigation of color-sensory interactions in beverages has compared the response of a college age group with the response of a panel consisting of a more mature population. Interestingly, the older group showed significant differences from the college age group in their response to the effects of color on several sensory parameters as well as showing a direct correlation between beverage consumption and color. Color is often taken for granted, but this position must be reevaluated in view of such studies and the need to create more appealing foods for different segments of our society.
Trigeminal neuralgia: can one case report support a treatment recommendation?
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Generally recognized as safe (GRAS) evaluation of 4-hexylresorcinol for use as a processing aid for prevention of melanosis in shrimp.
4-Hexylresorcinol (C12H18O2) is proposed for use as a processing aid for prevention of melanosis ("black spot") in shrimp and as an alternative to the currently approved sulfites. A safety evaluation was conducted to affirm, based upon scientific procedures, the generally recognized as safe ("GRAS") status of 4-hexylresorcinol for proposed use. The GRAS safety evaluation compiled, reviewed, and analyzed data on the following areas: chemical identity, analytical methodology, historical and proposed uses, functionality, and safety. The publicly available safety data on 4-hexylresorcinol cover a broad range of potential toxicity concerns including acute and subacute toxicity, subchronic toxicity, carcinogenicity, mutagenicity, and allergenicity. These studies, along with the aforementioned data, demonstrate that 4-hexylresorcinol presents no risk of toxicity at the levels proposed for treatment of shrimp, and the use of 4-hexylresorcinol as a processing aid to prevent melanosis in shrimp is GRAS.
The influence of zinc, magnesium, and iron on calcium uptake in brush border membrane vesicles.
The effects of adding increasing concentrations of magnesium (Mg), zinc (Zn), and iron (Fe) on calcium (Ca) uptake into rat brush border membrane vesicles was measured. At ratios of 1:1, based on the RDA, none of these minerals were found to significantly decrease calcium uptake. Mg, however, inhibited Ca uptake at an RDA ratio of 3:1 (Mg:Ca). At higher RDA ratios (Zn:Ca 10:1), Zn also decreased Ca uptake. In a comparison of the molar ratios of the above cations, Zn inhibited Ca uptake the most (0.12:1), possibly by competing directly at high-affinity Ca binding sites. Fe did not decrease Ca uptake but rather demonstrated an enhancing effect at high concentrations (20:1). When mixtures of the above divalent cations were studied, the effects on Ca uptake could largely be explained by the actions of the ions individually.
The effects of postharvest treatment and chemical interactions on the bioavailability of ascorbic acid, thiamin, vitamin A, carotenoids, and minerals.
All recent health recommendations include admonitions to reduce calories, maintain desirable weight, reduce fat, increase complex carbohydrates, and ensure an adequate intake of nutrients. Such recommendations require that we know not only nutrient composition of foods, but also potential losses and decreased bioavailability due to postharvest treatment and chemical interactions. This article discusses in some detail the reactions of concern that cause such changes and their potential alleviation with several key nutrients. The nutrients discussed were chosen as a result of the conclusions of the Joint Nutrition Monitoring Report of the Department of Health and Human Services and the U.S. Department of Agriculture. Obviously other choices could have been made, but the authors felt that the nutrients chosen--ascorbic acid, thiamin, vitamin A, carotenoids, calcium, and iron--were representative of a key profile of nutrients whose reactivity makes them vulnerable to losses in bioavailability, as well as being noted in the Joint Nutrition Monitoring Report.
Solubility of inorganic iron as affected by proteolytic digestion.
The effects of enzymatic digestion on the iron-solubilizing properties of chicken muscle were examined. A water-soluble extract, an acid-soluble extract, and an acid-insoluble fraction were subjected to a simulated gastrointestinal digestion using pancreatin and/or pepsin: The solubility of added Fe was significantly affected only by the acid-insoluble fraction and increased linearly as pepsin digestion progressed from 0 to 4 h. A maximum was reached when this treatment was followed by a 1-h pancreatin digestion. Pepsin digestion products with molecular weight (MW) less than 10,000 solubilized significantly more Fe than those with MW greater than or equal to 10,000. In contrast pancreatin digestion products of MW less than 10,000 were not effective Fe-solubilizing agents. The influence of chicken breast muscle on added Fe solubility appears to be related to the production of digestion intermediates that can act as ligands in the formation of soluble Fe complexes.
Dietary iron: chemistry and bioavailability.
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A view of a viewpoint: nutritional considerations.
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Nutritional realities--where does technology fit?
Food technology involves much more than fortification. It encompasses processing, i.e., a means of maintaining food in an acceptable, safe, and nutritious form for an extended period. Preservation processes free us from dependence on solely fresh foods. Thus, technology provides us with a stable food supply the year round and removes the threat of seasonal starvation. By increasing food acceptability through technology, the nutritional status of a population can be raised since the food will actually be eaten. To make technology the servant, rather than the master, however, more research is needed--for example, to establish the bioavailability of fortification nutrients.
Colorimetry--methodology and applications.
Color and appearance, those nebulous aspects of food acceptability which are taken for granted by most consumers, are coming under increasingly severe scrutiny. For this reason, it is essential that an adequate knowledge base for measurement be available to those working in the field. This base must be grounded upon the fact that color is a sensory phenomenon, and its measurement must include the physical, psychological, and physiological aspects. That is, measurement must involve tristimulus colorimetry, whether obtained by spectrophotometric or colorimetric techniques. It is the object of this article to review the general area of tristimulus colorimetry along with the techniques required for measurement. It is essential to include a section on the manipulation of data as well, since colorimetric data is often misused. Further treatment will be given to object-light interactions and how these affect not only measurement but sample perception, since manipulation of the physical parameters of the sample can affect the total appearance and color. Instruments and their usage will be reviewed so that decisions may be made on the correct instrument for a particular measuring system. In addition, a section will be devoted to on-line color measurement which may facilitate continuous processes. A final section of this article will deal with some advances in data manipulation and the development of new scales for color measurement. Fundamental colorimetric theory is essential in this area for proper usage. It is the aim of this paper to integrate theory with application in order to facilitate optimization of both the color of food and its measurement.
The psychophysical relationships between color and flavor.
Psychophysics has become a well-defined discipline in science and is undergoing a period of transition from the theoretical and academic to the applied. Certainly the use of magnitude estimation in flavor evaluation is becoming more accepted, and concurrently the food research area is utilizing the colorimetric techniques which are available. However, there has been virtually no investigation carried out on the quantitative relationships which exist between color and flavor in a psychophysical sense. Intuitively, many researchers state the qualitative effect of color on flavor, but the quantification of these techniques is practically nonexistent. This paper will attempt to summarize the psychophysical techniques which are available for such studies, as well as discuss the importance of these studies. Great controversy exists concerning the need for colorants in food. If color does indeed affect flavor quantitatively, it will affect intake and, therefore, final nutritional status of the public in a quantitative manner. This controversy should be resolved in the light of fact, not intuition.
Iron sources used in food fortification and their changes due to food processing.
The effect of food processing on the biological availability of iron in iron-fortified foods is critically reviewed. Studies on changes in the chemistry of the iron in processed foods are examined. Various iron sources currently used in food fortification in the U.S. are defined with emphasis on their biological availabilities under various conditions. The availability of iron in foods depends upon numerous factors, most of which are not fully understood. A factor which is often overlooked is the interaction of the iron with the food during events such as cooking or processing. Chemical changes in the iron compounds occur which may correlate with changes in the biological availability.
Dietary iron--chemistry and bioavailability.
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