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PubMed1998

On the molecular characteristics, compositional properties, and structural-functional mechanisms of maltodextrins: a review.

Compositional, physicochemical, and structural properties of maltodextrins and the most important advances that have been made are critically reviewed. Individual topics focuses on the maltodextrin production, carbohydrate composition, and dextrose equivalent determination, factors that alter the polysaccharide properties, the molecular arrangement, the mechanisms and complex physicochemical changes of maltodextrins such as water interaction (hygroscopicity, precipitation, turbidity, bound and free water) and the role of molecular interactions for a network formation. Of particular importance is the information concerning the network structure of maltodextrins gels (degree of crystallinity, crystallite size, aggregation) and the involvement of linear and branched chains for the network formation. Rheological properties have become a desirable tool to predict and understand their structural and functional properties, in single and in mixed systems with other macromolecules. These advances are assessed together with the structural development of food products and processes. Their main food applications, particular advantages, recent commercial directions, and modifications together with potential problems are also discussed. As food ingredients, maltodextrins are a valuable production tool, but still with considerable promises. Nevertheless, a more detailed knowledge of the properties of maltodextrins is necessary in order for their use to be considered as sufficiently effective and desirable in a number of known food applications and for novel development purposes.

Chemical Precipitation↗
PubMed2005

Parasites of the superorganism: are they indicators of ecosystem health?

The concept of ecosystem health is derived from analogies with human health, which subsequently leads to the implication that the ecosystem has organismal properties, a 'superorganism' in the Clementsian sense. Its application and usefulness has been the subject of a contentious debate; yet, the term 'ecosystem health' has captured the public's imagination and woven its way into the current lexicon, even incorporated into public policy. However, the application of parasites as bioindicators of ecosystem health poses a curious conundrum. Perceptions of parasites range from mild distaste to sheer disgust among the general public, the media, environmental managers and non-parasitologists in the scientific community. Nevertheless, the biological nature of parasitism incorporates natural characteristics that are informative and useful for environmental management. The helminths in particular have evolved elegant means to ensure their transmission, often relying on complex life cycle interactions that include a variety of invertebrate and vertebrate hosts. The assemblage of these diverse parasites within a host organism potentially reflect that host's trophic position within the food web as well as the presence in the ecosystem of any other organisms that participate in the various parasite life cycles. Perturbations in ecosystem structure and function that affect food web topology will also impact upon parasite transmission, thus affecting parasite species abundance and composition. As such, parasite populations and communities are useful indicators of environmental stress, food web structure and biodiversity. In addition, there may be useful other means to utilise parasitic organisms based on their biology and life histories such as suites or guilds that may be effective bioindicators of particular forms of environmental degradation. The challenge for parasitology is to convince resource managers and fellow scientists that parasites are a natural part of all ecosystems, each species being a potentially useful information unit, and that healthy ecosystems have healthy parasites.

Animals↗
PubMed2005

Sex-specific life history patterns in bluegill (Lepomis macrochirus): interacting mechanisms influence individual body size.

The ultimate body size that an individual fish achieves can be a function both of direct effects of growth or indirect effects associated with the timing of sexual maturation (and associated energetic tradeoffs). These alternatives are often invoked to explain variation in body size within and among fish populations, but have rarely been considered simultaneously. We assessed how resource availability and timing of maturation interact to influence individual body size of bluegill (Lepomis macrochirus). Resource availability (high and low food) and the social structure of the population (presence or absence of large, mature males) were varied in experimental ponds. Food ration affected growth (larger fish in the high food treatments) and the social structure of the population affected timing of maturation (early maturation of males in the absence of large males). Treatment effects, however, were sex-specific; males responded to the social structure of the population and females were more responsive to resource availability. We also found individuals that became sexually mature were smaller than those that remained immature, although results were sex-specific and resource dependent. For males, individuals that matured were smaller when resources were limited; mature and immature females showed no difference in body size regardless of food ration. We show that both resource availability and the processes that control timing of maturation interact in sex-specific ways to influence body size of bluegill. These results suggest that a more robust explanation for variable body size requires consideration of sex-specific interactions between ecological (food and growth) and evolutionary (timing of maturation) mechanisms.

Animal Nutritional Physiological Phenomena↗
PubMed1999

Glycemic index, cardiovascular disease, and obesity.

Although Americans have decreased the percent of energy they consume from fat, obesity and obesity-related comorbidities have progressively increased. Less attention has been paid to the role of carbohydrates, especially carbohydrate source, in these metabolic diseases. However, recent epidemiologic studies demonstrate consistently higher rates of cardiovascular disease and type II diabetes in individuals deriving a greater percentage of energy from refined grains and simple carbohydrates than from whole grains. Differences in the metabolic response to carbohydrates can be classified by glycemic index (GI), the blood glucose response to a given food compared with a standard (typically white bread or glucose). Classification of carbohydrates as "simple" or "complex" is of little use in predicting GI, because GI is influenced by starch structure (amylose versus amylopectin), fiber content, food processing, physical structure of the food, and other macronutrients in the meal. Low-GI diets have been reported to lower postprandial glucose and insulin responses, improve lipid profiles, and increase insulin sensitivity. Moreover, high-GI diets stimulate de novo lipogenesis and result in increased adipocyte size, whereas low-GI diets have been reported to inhibit these responses. Thus, the GI of dietary carbohydrates appears to play an important role in the metabolic fate of carbohydrates and, consequently, may significantly affect the risk of cardiovascular disease, diabetes, and obesity.

Blood Glucose↗
PubMedDate not supplied

[Methods for the study of microbial communities in fermented foods].

The importance of ecological concepts to understand the presence and growth of microorganisms in foods is presently recognized. The production of fermented foods under controlled conditions and its safety assurance depend on the knowledge and control of their microbiota. Traditional fermented foods are obtained by natural fermentations (in which no inoculum is added) and contain complex microbiotas, which are difficult to describe through the use of traditional microbiological methods. The microbial structure of these foods can be studied with different approaches. One of them consists on the typification of isolated microorganisms with methods based on DNA as RFLP, ribotyping, AFLP, ARDRA and RAPD. In order to detect non-culturable or not yet cultured microorganisms, nucleic acids are directly extracted from foods and the microbial diversity is determined from them. Examples of these techniques are the construction of 16S rDNA clone libraries and fingerprinting techniques, such as DGGE and TGGE. Recent advances on the application of these techniques on the study of fermented foods are presented.

Bacteria↗
PubMed1986

Nutrition and the pulmonary parenchyma.

Fasting and starvation affect various aspects of lung structure and function in experimental animals. Short-term food deprivation influences lung metabolism and biochemistry; prolonged partial food restriction affects lung structure and mechanics as well. This article provides a historical review of the topic and summarizes data obtained in humans and animals.

Adolescent↗
PubMed2005

Comparison between Sardinia and Malta: the Mediterranean diet revisited.

The Mediterranean diet is often characterized in terms of food items only. In this paper, the comparison of meals, in-between meals snack consumption and total daily food intake is presented between Sardinia and Malta in terms of structure, social environment and hours, together with their changes. Data were collected in 2001 in Sardinia and 2002 in Malta. A structured qualitative questionnaire, articulated around four main themes: food supply, transformation, preparation and consumption habits, was administered by face-to-face interviews with the help of a local person. Inquiries were carried out over two generations with 30 'mother-daughter' couples in each island. We highlighted some Mediterranean characteristics in Sardinia by showing striking contrasts between Sardinian and Maltese food habits such as meal preparation times, both breakfast and main meal structures, total daily food intake profiles, mealtimes and commensality in the mothers' generation. Some of these characteristics were also maintained in the daughters' generation. This investigation has presented evidence that beyond foods, meal pattern, structure and commensal rituals appeared as fundamental aspects of Sardo-Mediterranean food habits, which are important to consider when trying to maintain or implement the Mediterranean dietary model.

Adult↗
PubMedDate not supplied

Food safety: risk assessment methodology and decision-making criteria.

As our scientific technology grows, risk assessment methods become more complex and, therefore, open to greater scientific debate. Risk assessment has always been a part of the regulatory notification and approval process for foods. However, the methodologies applied to risk assessment and decision-making have become diverse, dependent on a number of features, including the areas of the world in which one operates, the need to use cumulative risk assessment for pesticides and other ingredients or alternative risk assessment considerations for evaluating nontraditional or bioengineered foods. Diverse institutional structures within a single federal regulatory authority may tend to lead to diversity in risk outcomes that creates policy decisions that complicate and confuse the risk management process. On top of this challenge, decisions become more complicated by the need to examine beneficial factors of foods rather than the adverse effects of foods and food additives. Foods are a complex mixture of ingredients. Regulatory groups recognize the need to use new approaches for evaluating the safety and risks associated with foods and food additives, and to do so in a timely manner. The United States Food and Drug Administration (US FDA) in its need to ensure standards of "reasonable certainty of no harm" continues to explore alternative means to be responsive to petitioners as well as continue to examine scientifically validated means, e.g., quantitative structure-activity relationship (QSAR), and computer-assisted programs, within the approval process to assist in the evaluation of risks. Another means to improve the risk management process would include the cumulative risk assessment of pesticides that will, no doubt, be the beginning of more intensive efforts to understand cumulative exposures and the inherent risks from multiple pathways of exposure. The passage of the Food Quality Protection Act (FQPA) resulted in developing additional risk assessment methodologies and approaches to assess the potential for multiple exposures and risks. Addressing the international criteria used in decision-making related to foods safety assessment has resulted in acceptable intake values for food ingredients for carcinogens and noncarcinogens that, in general, tend to be more stringent in the United States compared to Europe. Clearly, the need for harmonization of risk assessment criteria and the impact of the decision process on regulatory approvals and safety assessment is a future need for the continued assurances of food safety. The topics presented in this paper are based on a symposium held in November 2002 at the annual meeting of the American College of Toxicology.

Animals↗
PubMed2000

Ovarian follicular dynamics in selected and control (relaxed selection) male- and female-lines of broiler breeders fed ad libitum or on restricted allocations of food.

1. The reproductive structures of 4 broiler breeder lines fed ad libitum or restricted were compared at 1st egg. The lines were contemporary male- and female-lines and their respective progenitor lines maintained without selection for 20 years. 2. The selected lines were larger and had more hierarchical yellow follicles than the relaxed lines. The numbers of positions in the hierarchy were greater in the selected lines. The number of atretic follicles and the proportion of multiple follicles were relatively high in the selected male-line. 3. There were more white follicles in the range 1.8 to 5.0 mm diameter in the selected male-line than in the relaxed line, whereas selection did not change white follicle numbers in the female-line. 4. Food restriction decreased the numbers of normal and atretic yellow follicles and the proportion of multiples but had no effect on the number of positions in the hierarchy. Restricted feeding decreased the number of white follicles 1.4 to 2.4 mm and increased follicles 2.4 to 5.0 mm diameter. 5. There was little change in age at 1st egg among lines fed ad libitum. Restricted feeding increased age at 1st egg and the difference was greater in female- than in male-lines and in relaxed compared with selected birds. 6. Abdominal fatness was similar among the lines fed ad libitum and was decreased by restricted feeding. 7. Oviduct weights were greater in selected than in relaxed lines and were decreased by restricted feeding only in the selected male-line. 8. The weight of the largest follicle was higher in the selected lines and in restricted compared with ad libitum-fed birds. Plasma triglyceride concentrations were lower in restricted birds from the selected and relaxed female-lines compared with the other groups. Differences in plasma oestrogen concentrations could not be detected.

Adipose Tissue↗
PubMed1996

Structural, material and economic influences on the food-purchasing choices of socioeconomic groups.

Australian and overseas studies have found that respondents in low socioeconomic groups are least likely to purchase food that accords with recommendations in dietary guidelines. British and United States researchers have proposed that this consistently observed association is partly due to structural, material and economic factors that differentially affect socioeconomic groups. This study tested that proposition. Specifically, this study examined the notion that socioeconomic variability in food-purchasing choices are in part a function of the availability, accessibility and affordability of food recommended by dietary guidelines. Data collected from socioeconomic groups in the general community, and information provided by welfare recipients living in low-income areas of Brisbane and Logan city provided little support for this notion. Although significant differences were found between socioeconomic groups in terms of their food-purchasing choices, most respondents from all socioeconomic groups shopped at large supermarkets where recommended food was readily available, few reported difficulties obtaining access to these facilities, and the price difference between recommended and regular foods was, in most cases, small or nonexistent. This evidence leaves largely unanswered the question of why socioeconomic groups differ in their food-purchasing behaviours.

Analysis of Variance↗
PubMed1992

Limiting factors of starch hydrolysis.

Foods appear as complex structures, in which starch may be present in different forms. These, including the molecular characteristics and the crystalline organization, depend on processing conditions and compositions of ingredients. The main changes in starch macro- and microstructures are the increase of surface area to volume ratio in the solid phase, the modification of the crystallinity as affected by gelatinization and gelation, and the depolymerization of amylose and amylopectin. Starch modification may be estimated by different methodologies, which should be selected according to the level of structure considered. When amylose and amylopectin are in solution, rapid and total hydrolysis leads to the formation of a mixture of linear oligosaccharides and branched alpha-limit dextrins. However, starch usually occurs in foods as solid structures. Structural factors of starchy materials influence their enzymic hydrolysis. A better understanding of the enzymatic process enables the identification of the structural factors limiting hydrolysis: diffusion of enzyme molecules, porosity of solid substrates, adsorption of enzymes onto solid substrates, and the catalytic event. A mechanistic modelling should be possible in the future.

Animals↗
PubMed1995

Sensitivity of nucleus tractus solitarius neurons to induced moderate hyperglycemia, with special reference to catecholaminergic regions.

Extracellular single-unit recordings have been carried out in the caudal part of the nucleus tractus solitarius of male rats anesthetized by i.v. infusion with Ketamine. The sensitivity of 38 cells to 0.2 ml of 0.55 M glucose i.v. administration has been studied. The spike frequency of 75% of these cells was affected by the induced moderate hyperglycemia and a majority of them was activated. Immunohistochemical data on 9 glycemia-sensitive neurons showed that all recording sites were within TH-immunoreactive regions of the caudal part of the nucleus (either in the A2 noradrenergic group, or the C2 adrenergic group). These results confirm the existence of glycemia-sensitive neurons in the nucleus tractus solitarius, and suggest that these cells might mediate the effects of physiological fluctuations in blood glucose level on the control of food intake and metabolic regulations. The localization of these cells in catecholaminergic regions suggests that adrenaline and/or noradrenaline efferents might convey feeding relevant information concerning glycemic level or satiety signal from the nucleus tractus solitarius to forebrain structures involved in food intake, such as the perifornical lateral hypothalamic area and the paraventricular nucleus.

Animals↗
PubMed1993

[The present health and nutritional status of the pediatric population in the area of Orava].

410 children aged 11-14 years and 311 adolescents aged 15-18 years were examined in the region Orava. This region was selected for the survey because of high unemployment rates. The survey was focused on changes in nutritional indices in children and adolescents, as a consequence of changed food consumption patterns, caused by increased food prices and global socio-economic regression. Biochemical markers showed negative trends in serum lipid levels, especially a high prevalence of hypercholesterolaemia as well as that of vitamin C hyposaturation. This finding is related to impaired structure of consumed food, intake of food items of lower nutritional value, low intakes of fruit and vegetables, as shown by the analysis of dietary data.

Adolescent↗
PubMed2000

Comparison of central administration of corticotropin-releasing hormone and urocortin on food intake, conditioned taste aversion, and c-Fos expression.

Corticotropin-releasing hormone (CRH) is a potent regulator of the hypothalamic-pituitary-adrenal axis, and reduces food intake when administered into the third cerebral ventricle (i3vt). However, CRH also promotes conditioned taste aversion (CTA) learning which indicates that its anorectic effects are accompanied by aversive consequences that would reduce food intake independently of energy regulation. Urocortin (Ucn) is a closely related mammalian peptide that binds to both identified CRH receptor subtypes and also reduces food intake when administered i3vt. The present experiments compared the aversive consequences of i3vt administration of CRH and Ucn at doses that produced comparable decrements in food intake. Experiment 1 found that 1.0 microg Ucn and 2.0 microg CRH produced similar reductions in food intake. Experiment 2 demonstrated that, at these doses, CRH but not Ucn promoted robust and reliable CTA learning. A third experiment showed comparable increased c-Fos-like immunoreactivity after Ucn and CRH in forebrain and hindbrain structures associated with food intake. It is concluded that Ucn, at doses that reduce food intake to levels like that observed after administration of CRH, do not produce similarly aversive consequences.

Amygdala↗
PubMed2001

Accumulation of atmospheric and sedimentary PCBs and toxaphene in a Lake Michigan food web.

Seston, sediment, settling organic matter, and food web members were collected from Grand Traverse Bay, Lake Michigan, between April 1997 and September 1998 to examine PCB and toxaphene biomagnification. Stable isotopes of nitrogen and carbon were analyzed in samples and used to establish trophic structure of the food web and to determine the importance of atmospheric versus sedimentary sources in delivering PCBs to the food web. Nitrogen isotopes were confounded by multiple variables in this system, particularly seasonal variation, and did not display a simple pattern of enrichment among trophic levels. However, delta13C displayed little seasonal variation and was positively correlated with PCB concentrations among food web members (r2 = 0.69). Plots of delta13C vs PCBs separate food web members into three distinct groupings comprised of invertebrates, primary forage fish, and predatory fish. Stable isotope values of the primary organic sources indicate that the atmosphere, and not the sediment, is the most likely source of PCBs to the food web of Lake Michigan. Additionally, we suggest that seston may be important in delivering PCBs to pelagic food web members and species that receive a majority of their nutrition through pelagic sources. In contrast, settling particles are implicated in delivering PCBs to benthic organisms and Mysis relicta.

Animals↗
PubMed2005

Low-income mothers, nutrition and health: a systematic review of qualitative evidence.

Diet is a key issue for UK health policies, particularly in relation to poorer socio-economic groups. From a public health perspective, the government's role is to help low-income families to make healthy food choices, and to create the conditions to enable them to make healthy decisions. Arguably, however, current policy on nutrition and health is influenced by individualist and behavioural perspectives, which fail to take into account the full impact of structural factors on food choices. This paper draws on a systematic review of qualitative studies that prioritize low-income mothers' accounts of 'managing' in poverty, synthesizing a subset of studies that focus on diet, nutrition and health in poor families. Synthesis findings are explored in the context of dominant discourses concerning individual responsibility for health and gendered societal values concerning 'good' mothering. The paper concludes that a shift in emphasis in health policies, affording a higher priority to enabling measures that tackle the underlying determinants of health, would be advantageous in reducing nutritional inequities for low-income mothers and their children.

Child↗
PubMed1982

[Polysaccharide structure of cell wall preparations from the food protein yeast Candida spec. H].

More than 27% of the cell wall are unstably bound components: Proteophosphomannan as a main polysaccharide of the cell wall, mannose and manno-oligosides which are bound to peptides or phosphate. 19% are glycosidically linked with a phosphate bridge or O-glycosidically (Ser/Thr) linked with the protein which is covalently bound to the cell wall. Besides mannose and glucose, manno-oligosides and gluco-oligosides are involved in this linkage. A preparation consisting of glucan and chitin remains after careful degradation. It contains (1,2)-, (1,3)- and (1,6)- linked glucose, (1, 2, 3)-, (1, 2, 6)- or (1, 3, 6)-glucose-branchpoints and (1,4)-linked N-acetylglucosamine.

Candida↗