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Biomedical subjects

E Yáñez

Publications and source records attributed to E Yáñez.

At least 19 recordsLinked to original sources
PubMed1999

[Fat substitutes in human diet].

Fat consumption in developed countries has increased steadily during this century reaching values higher than 40% of the daily total calorie intake. This situation has resulted in a high prevalence of obesity, cardiovascular disease, diabetes and some types of cancer. The health agencies in these countries have made strong recommendations for the population to reduce dietary fat intake in order to reduce total fat intake to les than 30% of the total calories, with a maximum of 10% calories derived from saturated fats. The food industry has taken a very active role developing a number of low fat foods and opening a new area of products called fat substitutes in order to help the consumers reduce their fat consumption. One of these substitutes is a synthetic product obtained by reacting fatty acids from natural sources and sucrose. The product is a polyester of sucrose and has been named olestra. Olestra has been approved by the US Food and Drug Administration (FDA) to be used in snacks and fried chips. Due to its lipophilic nature olestra has a negative effect on the absorption of fat soluble vitamins and nutrients. However, this problem may be solved by supplementation of the nutrients affected. In addition, olestra may cause gastrointestinal effects such as abdominal cramping and stool softening. The Company that developed olestra claims to have solved this problem by modifying the composition of fatty acids of the product. Olestra is being marketed in the USA under the name of Olean.

Dietary Proteins↗
PubMed1998

Expression of the Schwanniomyces occidentalis SWA2 amylase in Saccharomyces cerevisiae: role of N-glycosylation on activity, stability and secretion.

The role of N-linked glycosylation on the biological activity of Schwanniomyces occidentalis SWA2 alpha-amylase, as expressed in Saccharomyces cerevisiae, was analysed by site-directed mutagenesis of the two potential N-glycosylation sites, Asn-134 and Asn-229. These residues were replaced by Ala or Gly individually or in various combinations and the effects on the activity, secretion and thermal stability of the enzyme were studied. Any Asn-229 substitution caused a drastic decrease in activity levels of the extracellular enzyme. In contrast, substitutions of Asn-134 had little or no effect. The use of antibodies showed that alpha-amylase was secreted in all the mutants tested, although those containing substitutions at Asn-229 seemed to have a lower rate of synthesis and/or higher degradation than the wild-type strain. alpha-Amylases with substitution at Asn-229 had a 2 kDa lower molecular mass than the wild-type protein, as did the wild-type protein itself after treatment with endoglycosidase F. These findings indicate that Asn-229 is the single glycosylated residue in SWA2. Thermostability analysis of both purified wild-type (T50=50 degrees C, where T50 is the temperature resulting in 50% loss of activity) and mutant enzymes indicated that removal of carbohydrate from the 229 position results in a decrease of approx. 3 degrees C in the T50 of the enzyme. The Gly-229 mutation does not change the apparent affinity of the enzyme for starch (Km) but decreases to 1/22 its apparent catalytic efficiency (kcat/Km). These results therefore indicate that glycosylation at the 229 position has an important role in the extracellular activity levels, kinetics and stability of the Sw. occidentalis SWA2 alpha-amylase in both its wild-type and mutant forms.

Blotting, Western↗
PubMed1991

Effect of processing on some chemical and nutritional characteristics of pre-cooked and dehydrated legumes.

The effect of processing on chemical composition and protein quality of three legumes was studied. The species analyzed were beans (Phaseolus vulgaris), Tórtola and Coscorrón varieties; lentils (Lens esculenta), Laird variety; and chick peas (Cicer arietinum), California-INIA variety. The legumes were soaked in a solution of Na2 EDTA at 0.03% for 16 h and cooked for a predetermined period for each species. They were dried in a tray drier with cross currents of air flowing at a speed of 10 m/min until the residual moisture content was 8%. The water activity in the resulting products ranged from 0.574 to 0.587, thus completely assuring no microbial activity. No important changes were observed in the legumes protein, fat, or fibre contents after processing. The soaking solution was effective in reducing the phytic acid content from 2.99 to 1.64 mg/100 g in the Tórtola beans, which had the highest acid value prior processing. In all the species the heat treatment reduced the activity of the trypsin inhibitors by at least 50%. Cooking and drying significantly increased protein digestibility in all the legumes studied, with chick peas showing the most dramatic increase: form 54.7% pre-processing to 94.9% post-processing. With regard to Net Protein Ratio (NPR), chick peas had a value of 4.03, followed by Tórtola beans (3.29), Coscorrón (3.09) and lentils (2.61). The NPR value for the casein diet was 4.20.

Desiccation↗
PubMed1989

[Preparation and chemical and nutritional evaluation of an infant food based on sweet lupine, wheat and milk].

This paper deals with the development of a food for infants and young children based upon a mixture of 27.5% wheat flour, 20% sweet lupin flour and 20% powdered milk (GL) (18% fat content) with added vitamins and minerals. The blend of wheat and lupin flour was processed in an extrusion-cooker (Wenger X 25) before mixing with the other ingredients. The proximate chemical analysis performed on the wheat-lupin-milk blend (LTL) showed 18.7% protein and 12.5% fat with a calculated caloric value of 427 kcal/100 g. Amino acid analysis indicated a deficiency of methionine + cystine and of threonine in the blend. Nevertheless, studies with rats on the biological quality of the protein, such us protein efficiency ratio and apparent digestibility, revealed that this blend was as good as the reference diet (powdered egg). It is therefore felt that the LTL blend may be a useful substitute in food programs directed to infants and school children.

Amino Acids↗
PubMed1989

[Fortification of bread with bean flour (Phaseolus vulgaris, L.). I. Flour and bread aspects].

This paper deals with the incorporation of bean flour (Phaseolus vulgaris, var. Tórtola) (BF) made at laboratory scale in bread enrichment, by substituting 2, 4, 6, 8 and 10% wheat flour by bean flour. First, wheat and bean flours blends were prepared to study the farinological properties of these combinations. Then, breads containing bean flour in the above-mentioned proportions were made. At the 6, 8 and 10% levels, a deterioration in farinological properties of the blends, such as water absorption, developing time, weakening and W value were evident. Baking tests showed that no significant changes occurred with respect to water absorption, mixing time, weight and volume of breads, and color and texture of crumb in BF levels of 2, 4 and 6%. However, overall qualities of the breads were significantly impaired at the 8 and 10% levels.

Bread↗
PubMed1989

[Fortification of bread with bean flour (Phaseolus vulgaris). II. Nutritive value of the fortified bread].

The protein value of breads containing bean flour (BF) (Phaseolus vulgaris, cv Tórtola) was tested in rats. BF replaced wheat flour by 2, 4, 6, 8 and 10 per cent. Protein content was 9.3 (N x 5.7) per cent and 24.4 (N x 6.25) per cent for wheat flour and bean flour, respectively. The protein content in the control bread was 11.6%, and increased to 12.6% at the 10% level of substitution. Parameters measured were protein efficiency ratio (PER), net protein ratio (NPR), and apparent and true digestibility of the protein. PER, in the control bread, was 1.44; a slight, non-significant increase occurred up to the 10% level of substitution. The control bread showed a NPR value of 2.78, figure which also remained practically unchanged at the higher levels of replacement. Nevertheless, both apparent and true protein digestibility decreased significantly with increasing levels of substitution of WF by BF (p less than 0.05). In conclusion, substitution of WF by BF in bread did not produce the expected increase in protein quality under our experimental conditions.

Analysis of Variance↗
PubMed1987

[Supplementation of wheat flour with chickpea (Cicer arietinum) flour. II. Chemical composition and biological quality of breads made with blends of the same].

Experimental bread made of wheat flour complemented with 5, 10 and 15% chick-pea flour was studied, using wheat bread as control. Samples were analyzed for their proximal chemical composition and amino acids content. Crude fiber and protein increased from 0.36% to 0.55%, and from 14% to 17.6%, respectively, when 15% chick-pea flour was added. The lysine content increased as the level of supplementation was raised. Biological quality of proteins was measured in rats as protein efficiency ratio (PER) as well as apparent digestibility resulting in an increase of PER values from 0.90 to 1.34 and small variations in bread protein digestibility. Bread nutritive value was significantly improved by adding chick-pea flour.

Amino Acids↗
PubMed1986

Long-term validation of 1 g of protein per kilogram body weight from a predominantly vegetable mixed diet to meet the requirements of young adult males.

Eight healthy young men participated in a 90-d metabolic balance study designed to assess the adequacy of 1 g of protein (N X 6.25) per kilogram body weight per day provided by a predominantly vegetable diet. The mean gross energy intake of the subjects was 49 kcal/(kg X d). The individuals received the experimental diet for eleven 8-d experimental periods. Three isoenergetic, isonitrogenous meals were served at 0800, 1200 and 1900. Anthropometric measurements and biochemical determinations in blood were made at the beginning of the study and afterwards at regular 15-d intervals. Body weight was measured daily. The mean overall weight change for the group was -0.8 kg. The mean daily urinary nitrogen output decreased from an initial value of 134.6 mg/(kg X d) to a final figure of 115.1 mg/(kg X d) (P less than 0.01), while the daily fecal N decreased from 31.5 to 26.3 mg/(kg X d) (P less than 0.05). Mean cumulative nitrogen balances were slightly positive for seven out of the eight individuals with an overall mean nitrogen balance value of +6.7 mg N/(kg X d). Biochemical and hematological values showed no significant changes throughout the study, except for a decrease in serum cholesterol. It is concluded that the "Chilean" mixed diet fed at the level of 1 g of protein per kilogram body weight per day with sufficient energy meets the long-term protein-energy needs of healthy young men, thus supporting the 1984 FAO/WHO/UNU safe recommended daily protein allowance of 0.75 g of reference protein, with a correction for the lower digestibility of vegetable sources.

Adult↗
PubMed1986

Food and nutrition knowledge in Chilean high school graduates.

The purpose of this study was to determine the degree of knowledge on food and nutrition in students graduating from high school in the Metropolitan Area of Santiago. The sample included 272 students of both sexes and type of school (public and private) and from high, medium and low socioeconomic level (SEL), measured through the Graffar Modified Scale. The degree of knowledge on food and nutrition was measured through a test of 48 items based on curriculum program objectives. The test covered three areas: Area 1, Food and Requirements; Area 2, Food, Personal and Environmental Hygiene, and Area 3, Nutritional Physiology. Students showed a good achievement of the food and nutrition objectives that are considered essential for obtaining and adequate nutrition and health status. Students from high SEL registered a significantly higher degree of knowledge on food and nutrition than students from other strata (p less than 0.001). However, sex and type of school had no effect on the degree of food and nutrition knowledge. This study is a contribution to the better understanding of factors affecting the food and nutrition knowledge, and provides good foundations for further studies.

Adolescent↗
PubMed1985

[Sensory evaluation and acceptability study, at the consumer level, of bread supplemented with sweet lupine flour].

The purpose of this study was to determine the effect of incorporating sweet lupine flour (SLF) to bread, upon the organoleptic characteristics and acceptability of the product. The substitution levels were 3, 6, 9 and 12%. The sensory evaluation test was done by 25 trained judges using the hedonic scaling method (9 to 1 scoring). Internal and external characteristics of appearance, color, aroma, texture, bitterness and flavor, as well as general acceptability, were measured. Sensory evaluation results of the external characteristics were significant at the 9 and 12% SLF levels for color (p less than 0.05) while the other parameters did not show significant differences. In regard to the internal characteristics, a significant difference for color was found at the 3% level of SLF (p less than 0.05); and at 6, 9 and 12% SLF levels, for appearance (p less than 0.05). The general acceptability was good at all the levels tested, with no significant differences among them. An acceptability study at the consumer level for 9% lupine flour bread was carried out in a group of 90 girls, aged 10-12 years, during a 10-day period. The results showed a very good acceptability of the product (p less than 0.01). The results of this study indicate that the incorporation of 6% SLF to the bread, did not affect adversely its sensory properties. Moreover, the acceptability of bread containing up to 12% SLF was excellent.

Bread↗
PubMed1983

Chemical and nutritional evaluation of sweet lupines.

Sweet lupines are presently being cultivated at the Experimental Station in Gorbea (Chile). Four cultivars, Lupinus albus cv Astra, L. albus cv Multolupa, Lupinus luteus cv Aurea and Lupinus angustifolius, were examined for the chemical composition of whole and dehulled seeds and testa. Whole seeds contain 34-35% protein. The varieties of L. albus contain 13% oil. L. luteus and L. angustifolius contain about 5% ether extract. Crude fiber ranged from 11 to 17% in the whole seed. Unsaturated fatty acids, especially oleic and linoleic, make up about 80% of total fatty acids. The alkaloid content of the seed was 0.02%. The amino acid composition of the protein indicated that the main deficiency corresponds to the sulfur-containing amino acids, i.e. methionine + cystine. The protein efficiency ratio values for L. albus cv Multolupa was 1.08 and 2.50 for casein. Supplementation with DL-methionine at 0.1, 0.2, 0.3 and 0.4% of the diet significantly increased the basal value from 1.08 to 2.14, for the supplemented diet with 0.1% (p less than 0.01). Higher levels of supplementation did not cause significant increases in the protein efficiency ratio. Apparent protein digestibility for the rat was 75% for unsupplemented lupine. This value increased to about 79% (p less than 0.01) for the supplemented diets (casein 88.7%).

Amino Acids↗
PubMed1983

[Sensory evaluation of bread with potato flour].

A sensory evaluation test was conducted in breads containing 2, 4, 6, 8 and 10% potato flour. The samples were sliced into equally sized pieces and served as coded randomized duplicates. All-wheat bread was used as a standard. The comparative preferences were rated on a 7-point hedonic scale (7 = very good, 1 = very bad) for appearance, flavor, texture and overall quality. The scores were statistically analyzed by the analysis of variance and the Chi square test. No significant differences were found in regard to flavor between the standard bread and bread containing from 2-10% potato flour. In the test of organoleptic quality, the bread containing 8% potato flour was rated as "good", as compared to "very good" for the all-wheat bread. However, this difference was not statistically significant. The values obtained in this study show that the incorporation of 6-8% potato flour in bread is perfectly feasible. This was obtained from a local food industry that in manufacturing the flour, used the Spartan variety potato produced in the southern region of Chile.

Bread↗
PubMed1983

[Formulation and nutritive value of 2 milk substitutes based on sweet lupine (Lupinus albus, var. multolupa)].

Two protein mixtures, A and B, based on sweet lupine, wheat flour and dried skim milk powder were formulated, bearing in mind the chemical and nutritional standards set by the National System of Health Services for protein mixtures used through the National Program of Complementary Feeding (PNAC) for preschool children. Both formulas contained 12% of sweet lupine flour, but they differed in their skim milk content, which was 15% in mixture A, and 10% in mixture B. Taking as reference value a content of 2% moisture, formula A contains 17.6% protein and mixture B, 16.4%, with a caloric content of 420 kcal/100 g for both of them. The amino acid score was 0.80 for both mixtures. The biological quality of the proteins of A and B, measured as protein efficiency ratio (PER), was 2.2 and 2.1, respectively. These values are not statistically different, although they are lower than the value of 2.5 obtained for casein (p less than 0.01).

Amino Acids↗
PubMed1982

Capacity of the Chilean mixed diet to meet the protein and energy requirements of young adult males.

1. The capacity of the Chilean mixed diet to meet the daily protein and energy needs was tested in eight subjects aged from 20 to 31 years using the nitrogen balance method. This diet was tested at the protein levels of 0.40, 0.55 and 0.70 g/kg body-weight per d. 2. An egg reference diet providing 0.30, 0.45 and 0.60 g protein/kg per d was also assayed. 3. The mean daily energy intake was 207 kJ/kg per d according to subjects' previous intake and activity pattern. 4. The N balance response to each dietary protein level was taken as a measure of adequacy of protein intake, and regression analyses of N balance (Y) v. N intake (X) were calculated to estimate protein needs. The equations found were Y = 0.70X - 68.7 for the egg diet, and Y = 0.74X - 92 for the mixed diet. 5. From these equations the mean protein requirements for equilibrium were estimated to be 0.61 g/kg for egg and 0.78 g/kg for the mixed diet. 6. If the coefficient of variation is 15, the protein requirement for N equilibrium of 97.5% of the population would be 0.8 g/kg per d for egg and 1.0 g/kg per d for the mixed diet.

Adult↗
PubMed1982

Obligatory urinary and faecal nitrogen losses in young Chilean men given two levels of dietary energy intake.

1. The obligatory nitrogen losses were measured in young adult males of the low socio-economic group, consuming an N-free diet at 192 kJ (46 kcal)/kg per d from day 1 to 10 and 243 kJ (58 kcal)/kg per d from day 11 to 18. 2. All subjects, except one, lost weight compatible with N loss. 3. A kinetic evaluation of the results showed that the asymptotically derived urinary N loss after stability had been reached was 35.8 mg N/kg per d. The mean time to stability was 6.5 d. The subjects showed a trend toward decline in N loss while consuming the high-energy N-free diet. 4. The obligatory faecal N loss for days 1-10 was 16.1 mg N/kg per d and 8 mg N/kg per d for days 11-18. 5. Based on the factorial approach the total obligatory N loss of our subjects, for the initial 10 d, was 57.5 mg N/kg per d.

Adult↗
PubMed1982

[Enrichment of bread with soy flour].

A series of laboratory studies was conducted to test the effect of the inclusion of soy flour in bread at the levels of 2, 4, 6, 8, 10 and 12%. The farinographic tests showed that several changes occurred with the incorporation of soy flour to the wheat flour, such as an increase in water absorption and weakening of the dough, and a decrease in the dough developing time. The mixing time remained unchanged up to the level of 8% substitution. Higher levels produced an increasing stickiness of the dough that made its handling more difficult. Soy-containing breads were slightly darker than wheat bread with a score of 71 points (scale 100) for the 12% level of substitution. The texture became coarser with increasing substitution of soy flour. Starting with the level of 4% of soy flour a volume decrease was observed, but this was corrected by the addition of 0.5% sodium stearoyl-2-lactylate (SSL). At the levels of 10 and 12% of soy flour, SSL was not effective in preventing the reduction of volume. The chemical composition of bread showed a regular increase in its protein content from 13.4, to 18% in the bread containing 12% soy flour. The protein efficiency ratio of bread improved from 1.17 for the wheat bread, to 2.13 for the bread containing 6% soy flour (casein, 2.54). Our results confirm the observation made by other workers in that the inclusion of soy flour in bread improves both the protein concentration and quality of this basic food.

Bread↗
PubMed1982

[Chemical and nutritional evaluation of triticale (Secale sp.) cultivated in Chile].

Six varieties of triticale and two varieties of wheat flours were analyzed for their proximal composition. The protein content of triticale flours ranged from 7.2 to 11.0%, and that of wheat flours, was 10.8 and 10.9%, respectively. The biological quality of Tca 8-74, measured as PER in Wistar rats, was 1.14, while that of commercial wheat flour was 0.85 (P less than 0.05). Amino acid supplementation of triticale flour with 0.2% L-lysine or 0.4% DL-threonine did not improve the biological quality of the protein. Supplementation with both amino acids, however, significantly improved both weight gain and PER. The value for the latter was 2.59 as compared to 2.62 for the standard casein diet. A panification assay was carried out using triticale, wheat and triticale: wheat blends in the following proportions: 1:0; 3:1; 1:1; 1:3; 0:1, and all of the breads were tested for their PER in rats. The PER for wheat bread and triticale bread was 1.05 and 1.25, respectively. None of the breads made from the wheat and triticale blends improved its protein quality beyond that of the wheat or triticale breads. The results of this study indicate that triticale has a better protein quality than wheat; furthermore, it may be used either alone or mixed with wheat in panification without affecting its protein value.

Amino Acids, Essential↗