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PubMed2002

Squeezing flow viscometry for nonelastic semiliquid foods--theory and applications.

In most conventional rheometers, notably the coaxial cylinders and capillary viscometers, the food specimen is pressed into a narrow gap and its structure is altered by uncontrolled shear. Also, most semiliquid foods exhibit slip, and consequently the measurements do not always reflect their true rheological properties. A feasible solution to these two problems is squeezing flow viscometry where the specimen, practically intact and with or without suspended particles, is squeezed between parallel plates. The outward flow pattern mainly depends on the friction between the fluid and plates or its absence ("lubricated squeezing flow"). Among the possible test geometries, the one of constant area and changing volume is the most practical for foods. The test can be performed at a constant displacement rate using common Universal Testing Machines or under constant loads (creep array). The tests output is in the form of a force-height, force-time, or height-time relationship, from which several rheological parameters can be derived. With the current state of the art, the method can only be applied at small displacement rates. Despite the method's crudeness, its results are remarkably reproducible and sensitive to textural differences among semiliquid food products. The flow patterns observed in foods do not always follow the predictions of rheological models originally developed for polymer melts because of the foods' unique microstructures. The implications of these discrepancies and the role that artifacts may play are evaluated in light of theoretical and practical considerations. The use of squeezing flow viscometry to quantify rheological changes that occur during a product's handling and to determine whether they are perceived sensorily is suggested.

Elasticity↗
PubMedDate not supplied

Neuroendocrine factors regulating blood glucose, plasma FFA and insulin in the development of obesity.

A number of neurotransmitters and neuropeptides in the hypothalamus play a role in the control of food intake, metabolism, and body weight. Particularly, noradrenergic mechanisms in several areas of the hypothalamus are involved. Control of peripheral metabolism by the hypothalamus is achieved via autonomic modulation of the function of hepatocytes, adipocytes, and the endocrine cells in the islets of Langerhans. The autonomic control mechanisms ultimately lead to an appropriate shaping of blood glucose, plasma FFA, and insulin profiles to guarantee an adequate flow of nutrients under different physiological situations. Peripheral insulin and glucose can penetrate into the brain where they might affect the function of those brain structures involved in control of food intake, metabolism, and body weight.

Animals↗
PubMedDate not supplied

[An approach to food consumption in an urban environment. The case of west Africa].

West Africa has undergone rapid economic and political changes during the last 20 years. After the failure of economic policies implemented since independence, programs for structural adjustment have strongly influenced the economy. Food problems affect each country differently. The Sahel has experienced food shortages and starvation whereas in forested countries the food supply has remained stable. Nevertheless, food policies have not succeeded in contributing to urban and rural development. The rate of urbanization in west Africa is generally low but the rate of urban population growth is particularly high, much more than the growth rates of industry and infrastructure. Although metropolitan areas are affected by poverty, they offer more hope and opportunities than rural areas. Urban markets have expanded and diversified as social differences have also increased and contributed to changes in consumption structure. Urban growth has contributed to the increase of imported food: this is indicated by both the strong dependency and the change of food habits towards western food patterns. Recently however, west African urban dwellers are still preferring local items if they are affordable. When imported products are used, they are integrated within a stable meal plan consisting of a single dish with a base and a sauce, which is typical of African food preparation. Surveys of consumption-budgets are still only available on a national scale. These can provide accurate information about food consumption patterns of families, particularly for significant trends. However, they do not provide information about the dynamics of food consumption, neither for urban areas or the individual. Now a significant proportion of individual food consumption occurs outside of the home, mainly with food provided by street vendors. This new consumption habit is a response to the urban food crisis. Consumption of street-vendor-food comprises one component but this cannot be dissociated from in-home food consumption. Despite the growing importance of street-vendor food consumption, it has still not been adequately documented. Theoretically, food consumption is an evolving concept. Single disciplines, such as economics or nutrition, first studied food consumption. More recently, social sciences developed new approaches with various interpretations, which were sometimes contradictory. The evolution of urban food consumption and the numerous related problems support the approach proposed by some authors suggesting a mixed analysis integrating both economics and cultural factors. Operationally, a global and dynamic approach to food styles must consider urban heterogeneity and diversity of situations. For example, food consumption by people maintaining their in-home food habits shows the pertinence of studies focusing on individuals. Therefore, the food course concept may be a useful method for the study of food consumption.

Africa, Western↗
PubMed1996

Measurement of resistant starch in vitro and in vivo.

The digestibility of the starch in plant foods is highly variable, and is dependent on a number of factors, including the physical structure of both the starch and the food matrix. An in vitro technique has been developed to categorize starch in plant foods according to its likely rate and extent of digestion in the human small intestine. The in vitro method provides values for rapidly digestible starch, slowly digestible starch and resistant starch (RS). In the present study values for the RS content of foods, as measured by the analytical technique, were compared with the recovery of starch from these foods when fed to healthy ileostomates. Nine ileostomy subjects were given a polysaccharide-free diet with a breakfast supplement, on eac of 2 d (two subjects) or 3 d (seven subjects), of biscuits made from wheat, potato or banana flours or from moist-heat-processed wheat or maize flours. RS intakes measured in vitro ranged from 8.5 to 15.0 g/d for the test biscuits, and mean starch recoveries in ileostomy effluent were 100.4 (n5, range 91-106)% of those values, but there was substantial variation between individuals. It is proposed that RS is defined as 'the sum of starch and starch-degradation products that, on average, reach the human large intestine'. The analytical method for the measurement of RS in vitro based on this definition is shown to provide an accurate prediction of the average amount of starch that is likely to escape complete digestion and absorption in the human small intestine.

Adult↗
PubMed1991

Transactive memory in close relationships.

Memory performance of 118 individuals who had been in close dating relationships for at least 3 months was studied. For a memory task ostensibly to be performed by pairs, some Ss were paired with their partners and some were paired with an opposite-sex partner from another couple. For some pairs a memory structure was assigned (e.g., 1 partner should remember food items, another should remember history items, etc.), whereas for others no structure was mentioned. Pairs studied together without communication, and recall was tested in individuals. Memory performance of the natural pairs was better than that of impromptu pairs without assigned structure, whereas the performance of natural pairs was inferior to that of impromptu pairs when structure was assigned.

Adult↗
PubMed1977

[Why is bread consumption decreasing?].

In France bread plays a very special and ambivalent role among our foodstuffs because of the considerable drop in its consumption, its alleged harmful effects on our health and the respect in which it is traditionally held. More than half the 1 089 adults interviewed in this study say they have decreased their consumption of bread in the last 10 years. The reasons given vary according to age, body weight and urbanization level. The main reasons given for this restriction are the desire to prevent or reduce obesity, the decrease in physical activity, the general reduction in food consumption and the possibility of diversifying foods even further. Moreover, the decreasing appeal of bread in relation to other foods, as well as a modification in the structure of meals, in which bread becomes less useful to accompany other food, accentuate this loss of attraction. However, the respect for bread as part of the staple diet remains very acute as 95 p. 100 of those interviewed express a reluctance to throw bread away, more for cultural than economic reasons. Mechanization and urbanization having brought about a decrease in energy needs, the most common alimentary adaptation is general caloric restriction by which glucids, and especially bread, are curtailed.

Adult↗
PubMed2004

Are household factors putting immigrant Hispanic children at risk of becoming overweight: a community-based study in eastern North Carolina.

North Carolina has one of the fastest growing populations of Hispanic immigrants in the U.S. The prevalence of overweight among Hispanic children in the state has increased to 17%. Therefore, the objectives of this descriptive, exploratory study were to identify potential risk factors for childhood overweight at the household level among 128 immigrant Hispanic families with school-aged children living in Eastern North Carolina. Data concerning parental beliefs about overweight children, family participation in physical activity, and household availability of higher-calorie foods were collected using a structured, close-ended interview form. Forty-seven percent of parents believed that overweight children are unhealthy, 11% that if a child is overweight, it is God's will, and over 90% believed that overweight children should be taken to a nutritionist or physician for help with weight reduction. The activities undertaken by families four to seven times per week were watching television (70%), listening to music (69%), and reading (61%). Cookies, cold cereals, crackers, whole milk, ice cream, cheese, hotdogs, peanut butter, soft drinks, fruit drinks, chips, and pudding were regularly available in a majority of households. Regression analysis indicated that household income, parental education, and rural versus urban residence had no significant impact on frequency of family participation in physical activity or household availability of higher-calorie foods. Findings suggest a need for bilingual community health professionals to develop culturally sensitive wellness programs targeted at immigrant Hispanic families that promote greater engagement in moderate-intensity physical activity and more frequent consumption of lower-calorie foods.

Adult↗
PubMed1990

[The participation of cholinergic structures at different levels in shaping the immediate adaptation of the pancreas to food quality in ontogeny].

The experiments on rats showed that the urgent enzymatic adaptations of the pancreas to the quality of food have not been inherent, but have been created in the ontogeny. These adaptations are usually absent during transition to the definitive feeding (23rd day of life). Adaptation for protein stimulant appears in the moment of taking away of mother (30th day of life) and becomes persistent for protein and fat stimulants by the 90th day of life (adult rats). The blockade of different levels' cholinergic structures prevents the normal development of urgent specific pancreas adaptations in all investigated ages.

Adaptation, Physiological↗
PubMed2003

Assessment of the potential allergenicity of ice structuring protein type III HPLC 12 using the FAO/WHO 2001 decision tree for novel foods.

The introduction of novel proteins into foods carries a risk of eliciting allergic reactions in individuals sensitive to the introduced protein. Therefore, decision trees for evaluation of the risk have been developed, the latest being proposed by WHO/FAO early in 2001. Proteins developed using modern biotechnology and derived from fish are being considered for use in food and other applications, and since allergy to fish is well established, a potential risk from such proteins to susceptible human beings exists. The overall aim of the study was to investigate the potential allergenicity of an Ice Structuring Protein (ISP) originating from an arctic fish (the ocean pout, Macrozoarces americanus) using the newly developed decision tree proposed by FAO/WHO. The methods used were those proposed by FAO/WHO including amino acid sequence analysis for sequence similarity to known allergens, methods for assessing degradability under standardised conditions, assays for detection of specific IgE against the protein (Maxisorb RAST) and histamine release from human basophils. In the present paper we describe the serum screening phase of the study and discuss the overall application of the decision tree to the assessment of the potential allergenicity of ISP Type III. In an accompanying paper [Food Chem. Toxicol. 40 (2002) 965], we detail the specific methodology used for the sequence analysis and assessment of resistance to pepsin-catalysed proteolysis of this protein. The ISP showed no sequence similarity to known allergens nor was it stable to proteolytic degradation using standardised methods. Using sera from 20 patients with a well-documented clinical history of fish allergy, positive in skin prick tests to ocean pout, eel pout and eel were used, positive IgE-binding in vitro to extracts of the same fish was confirmed. The sera also elicited histamine release in vitro in the presence of the same extracts. The ISP was negative in all cases in the same experiments. Using the proposed decision tree, we demonstrated the safety of the ISP to patients already sensitised to fish, as well as to individuals potentially susceptible to producing IgE responses to proteins. Furthermore, the practicability of the new decision tree was confirmed.

Adolescent↗
PubMed2002

Interaction modification among decomposers impairs ecosystem processes in lead-polluted soil.

Environmental pollution by toxicants is generally believed to lead both to direct toxic effects and indirect effects via altered species interactions in a stressed community. We examined how contamination of a coniferous forest soil floor by lead (from an abandoned shooting range area) may alter trophic interactions and decomposition processes. We constructed laboratory microcosms containing microbial-based food webs with various trophic structures: microbes alone; microbes with microbivorous-detritivorous enchytraeid worms (Cognettia sphagnetorum, a potential keystone species of boreal forest soil); and microbes, worms, and predatory mites (Lysigamasus spp.) together. The direct toxic effect of lead and the effectiveness of the predators in preying upon the worms were studied in separate experiments. Polluted humic soil (acid-extractable lead concentration was 2,720 +/- 349 mg/kg of dry soil [mean +/- standard error]) was toxic to enchytraeids, and predators effectively reduced worm populations. Positive density-dependent effects of worms on microbes and a trophic cascade from predatory mites to microbes, observed in the unpolluted humus, were not observed in the polluted humus, indicating pollution-induced interaction modification among organisms. Concomitantly, lead pollution altered the process of nutrient mineralization in the humic soil. However, causality and relative importance of direct toxicity and indirect effects of lead on the dynamics of the decomposer food web could not be pointed out. Examination of our results indicates that traditional food web models are incapable of predicting mechanisms that alter dynamics of pollution-stressed belowground food webs.

Animals↗
PubMed2002

Exploiting expolysaccharides from lactic acid bacteria.

Microbial exopolysaccharides (EPSs) synthesized by lactic acid bacteria (LAB) play a major role in the manufacturing of fermented dairy products. EPS production is characterized by a large variety in terms of quantity, chemical composition, molecular size, charge, type of sidechains and rigidity of the molecules. Monosaccharide unit's composition, linkages, charge and size determine the EPS' intrinsic properties and their interactions with other milk constituents. EPSs contribute to texture, mouthfeel, taste perception and stability of the final product. Furthermore, it was reported that EPS from food grade organisms, particularly LAB, have potential as food additives and as functional food ingredients with both health and economic benefits. A better understanding of structure-function relationships of EPS in a dairy food matrix and of EPS biosynthesis remain two major challenges for further applications of EPS and the engineering of functional polysaccharides.

Animals↗
PubMed1996

Nutrient intake in relation to bladder cancer among middle-aged men and women.

This population-based case-control study examined the association between selected nutrients, foods, and diet behaviors and bladder cancer. Bladder cancer cases (n = 262) were identified from the Surveillance, Epidemiology, and End Results Program cancer registry for western Washington, and controls (n = 405) were identified through random digit dialing. Cases were diagnosed between January 1987 and June 1990, and eligible subjects were Caucasian, aged 45-65 years, and residents of King, Pierce, or Snohomish counties. Subjects completed a self-administered, 71-item food frequency questionnaire and a structured telephone interview. Analyses were conducted by logistic regression analysis and included adjustment for age, sex, smoking (current, former, never), and county. Odds ratios and their 95% confidence intervals for highest versus lowest level of intake were examined. An inverse association was found between the risk of bladder cancer and dietary retinol (odds ratio (OR) across quartiles: 1.00, 1.09, 0.97, and 0.52; 95% CI 0.29-0.97; trend p value = 0.03) and dietary vitamin C (OR across quartiles: 1.00, 0.96, 0.67, and 0.50; 95% CI 0.28-0.88; trend p value = 0.009), adjusted for calories. The use of multivitamin supplements daily over the 10-year period ending 2 years before diagnosis versus no use was associated with a decreased risk of bladder cancer (OR = 0.39; 95% CI 0.24-0.63) as was use of supplemental vitamin C (OR for > 502 mg/day over the 10 years vs. none = 0.40; 95% CI 0.21-0.76). Increased intake of fruit was associated with a decreased risk of bladder cancer (OR across quartiles: 1.00, 1.24, 0.72, and 0.53; 95% CI 0.30-0.93; trend p value = 0.01, adjusted for calories), while increased use of fried foods was associated with an increased risk of bladder cancer (OR across quartiles: 1.00, 1.51, 1.81, and 2.24; 95% CI 1.25-4.03; trend p value = 0.006). This study provides modest evidence that certain nutrients, foods, and supplementation may affect the incidence of bladder cancer.

Aged↗
PubMed2001

Pyr c 1, the major allergen from pear (Pyrus communis), is a new member of the Bet v 1 allergen family.

Pear is known as an allergenic food involved in the 'oral allergy syndrome' which affects a high percentage of patients allergic to birch pollen. The aim of this study was to clone the major allergen of this fruit, to express it as bacterial recombinant protein and to study its allergenic properties in relation to homologous proteins and natural allergen extracts. The coding region of the cDNA was obtained by a PCR strategy, cloned, and the allergen was expressed as His-Tag fusion protein. The fusion peptide was removed by treatment with cyanogen bromide. Purified non-fusion protein was subjected to allergenicity testing by the enzyme allergosorbent test (EAST), Western blotting, competitive inhibition assays, and basophil histamine release. The deduced protein sequence shared a high degree of identity with other major allergens from fruits, nuts, vegetables, and pollen, and with a family of PR-10 pathogenesis related proteins. The recombinant (r) protein was recognised by specific IgE from sera of all pear-allergic patients (n = 16) investigated in this study. Hence, the allergen was classified as a major allergen and named Pyr c 1. The IgE binding characteristics of rPyr c 1 appeared to be similar to the natural pear protein, as was demonstrated by EAST-inhibition and Western blot-inhibition experiments. Moreover, the biological activity of rPyr c 1 was equal to that of pear extract, as indicated by basophil histamine release in two patients allergic to pears. The related major allergens Bet v 1 from birch pollen and Mal d 1 from apple inhibited to a high degree the binding of IgE to Pyr c 1, whereas Api g 1 from celery, also belonging to this family, had little inhibitory effects, indicating epitope differences between Bet v 1-related food allergens. Unlimited amounts of pure rPyr c 1 are now available for studies on the structure and epitopes of pollen-related food allergens. Moreover, the allergen may serve as stable and standardised diagnostic material.

Allergens↗