Rev Chil Nutr Vol. Low-calorie yogurt added with yacon flour: development and physicochemical evaluation. Correspondencia a :. Yacon flour has been used in several food products due to its high fructooligosaccharides and inulin contents, compounds that present health promoting properties. In this study, yacon flour was used as an ingredient in light yogurt in the following concentrations: 1. Centesimal composition, pH, soluble solids, acidity and apparent viscosity of the yogurt supplemented with yacon were determined.
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Rev Chil Nutr Vol. Low-calorie yogurt added with yacon flour: development and physicochemical evaluation. Correspondencia a :. Yacon flour has been used in several food products due to its high fructooligosaccharides and inulin contents, compounds that present health promoting properties.
In this study, yacon flour was used as an ingredient in light yogurt in the following concentrations: 1. Centesimal composition, pH, soluble solids, acidity and apparent viscosity of the yogurt supplemented with yacon were determined.
Results were evaluated through analyses of variance and regression. Centesimal composition of the yogurts allowed for their classification as low-fat foods, presenting low carbohydrate content and containing dietary fiber, especially those supplemented with more than 2.
Key words: fructooligosaccharides, inulin, prebiotics, yogurt, yacon. A growing concern regarding health and quality of life is causing people to value physical exercise, eating healthier foods and reducing consumption of those high in sugar, salt and fat. The main cause for this change in lifestyle and eating habits is a constant search for health, which assures a better quality of life and prevents diseases 1.
Parallel to this, there has been a rapid development in foods which present not only nutritional characteristics and proper technology, but also ingredients that have a biological role in preventing diseases and promoting health, known as functional foods 2. Yacon Smallanthus sonchifolius, Polymnia sonchifolia Poepp. One of the main characteristics of such carbohydrates is their ability to stimulate the growth of non-pathogenic bacteria through colonic fermentation, which causes them to be classified as bioactive components with claimed prebiotic effects 5 , and consequently, functional foods.
Because of the nutritional benefits presented by yacon, its flour has been developed and used as an ingredient in some foods.
This allows scientists to formulate products with low fat content, low caloric value and a high concentration of dietary fiber, especially FOS, which may provide a protective effect to customer health 6. In Brazil, the addition of yacon flour is reported mainly as an ingredient in cereal-based products, such as cakes, "Champurrada" type biscuits, snacks and breads 6, 7.
No application of this product is found whatsoever in drinks, since milk-based products are easily consumed and versatile with high physiological functionality, and also viewed as healthy products among consumers. Development of light yogurt supplemented with yacon flour may be a good alternative in the fermented food market, allowing the preparation of a drink with prebiotic claims due to its high soluble dietary fiber content especially FOS for aiding in the functioning the intestinal tract, regardless of consumer age.
The product may also contribute to reduce toxic metabolites and plasmatic cholesterol, improve mineral bioavailability, such as calcium, magnesium and phosphorus, contribute to the growth of bifidobacterium inside the colon, and also help in reduction of blood pressure 8. Based on these facts, the objective of the present study was to use different proportions of yacon flour as an ingredient in the preparation of light yogurts followed by evaluation of its effect on the physicochemical properties of the product.
Preparation of yogurts was conducted according to a completely randomized design, with four formulations and one control, in two repetitions. Four different concentrations of yacon flour were added to the yogurt prepared from skim milk and sweetened with aspartame 0. This estimate was based on yacon flour centesimal composition.
Thus, yacon flour was added to the yogurts at concentrations of 1. These values are calculated to provide 1. The yogurt serving size was set to be mL. The control yogurt consisted of a basic mixture of skim milk sweetened with aspartame, without addition of yacon flour. Yacon flour was produced according to the methodology described in Ribeiro 10 , being obtained from Process for production of light yogurt added with yacon.
Each yogurt formulation, control and the four different levels of yacon flour, was produced in two separate runs replication. Determination of the centesimal composition of the yogurts. The following analyses were performed: water content, via the gravimetric analysis method All measurements were made in duplicate. Results were reported as the average of duplicates for each experimental yogurt unit. Determination of FOS and inulin were carried out according to the method reported by Kaneko et al.
The carbohydrate fraction was determined to be the remaining portion of the sample after discounting the levels of water, protein, lipid, ash and total dietary fiber. Determination of the caloric value of the yogurts. Determination of Lab color values of the yogurts. The calculation was obtained from two readings for each run, with the yogurt sample being put inside a 4 mL polystyrene cuvette, and between readings the cuvettes were washed with distilled water.
Determination of apparent viscosity of the yogurts. These are temperatures of typical yogurt consumption and the general oral temperature This experiment lasted for 2 minutes and generated a total of 30 points.
Results were expressed in mPa. Results of physicochemical determinations were analyzed in a completely randomized design CRD 18 model, with 5 yogurt formulations and 2 repetitions. The effect of yacon flour supplementation was evaluated via regression analysis, in which linear and quadratic effects were tested according to changes in the concentration of yacon flour in the yogurt.
Centesimal composition of the yogurt Results of the centesimal composition of the yogurts are given in table 1. Mean values and standard deviation for centesimal composition and caloric value of the yogurts added of yacon flour. This was expected since the yacon root has low concentrations of these compounds 4.
This indicates the little influence that yacon may have on yogurt composition when used as an ingredient. This is in agreement with Brazilian regulations that demand a minimum of 2. Lipid content was lower than 0. Regression models were adjusted to evaluate variation of these components due to yacon flour supplementation to the yogurt table 2. Regression equations for the variation of the water content, ash, IDF, SDF, FOS and inulin due to yacon flour addition X and their respective coefficient of determination R 2 and probability value for the regression model F.
Greater concentrations of solids ash, total dietary fiber and carbohydrates for the same amount of product results in a linear reduction of water observed as yacon flour concentration increased. Therefore, a smaller concentration of solids and greater concentration of water was observed in the control yogurt when compared to yogurts with yacon flour.
A proportional growth in ash content was observed as the level of yacon flour added to the yogurt formulations increased in comparison to the control yogurt.
This growth may be caused by the higher levels of phosphorus and potassium in the flour, since yacon has significant concentrations of such minerals, According to Brazilian regulations, functional foods are those which present at least 1.
However, the yogurts containing more than 2. Therefore, the yogurts containing ore than 2. Values of total dietary fiber, FOS and inulin in the yogurts determined through the enzymatic-gravimetric and HPLC methods were lower than expected.
It is also noticeable that the amount of carbohydrates in the yogurt tends to decrease when yacon flour is added, presenting minimum levels when the yogurt contains 1. The yogurts with less addition of yacon flour presented a slight reduction in water content and an increase in total dietary fiber compared to the control yogurt.
This fact is rather justifiable because, the same quantity of yogurt presents a reduction in the level of carbohydrates, something that asks for the definition of a quadratic effect to account for such behavior. Bearing this in mind, it is justified that the same quantity of yogurt presents a reduced level of carbohydrates, something that requires the definition of a quadratic effect to account for such behavior table 2.
Since the difference in water content between the yogurts with more than 1. The caloric value ranged from The caloric value in this study was calculated based on protein, lipid and carbohydrate contents.
The increase in caloric value may be due to the change in carbohydrate content in the yacon flour. Results suggest that the addition of yacon flour to yogurt has little effect on the caloric value. Moreover, the product has increased level of dietary fiber which may cause a slower absorption of carbohydrates in the intestinal tract.
Average pH values for all five yogurts was 4. This is in agreement with Brazilian regulations which suggest a pH value of 4. Yogurts with pH values lower may be rejected by consumers and would favor coagulation due to reduction of proteins and lead to whey separation.
Values of pH higher than 4. This may result from coloring of flour, which happens due to enzymatic browning reactions by the presence of phenolic compounds 4 , and non-enzymatic browning during yogurt processing. Total soluble solids TSS contents increased linearly with addition of yacon flour to the yogurt. This may be linked to the higher level of fructans FOS and inulin in the yogurts with higher concentrations of yacon flour.
A quadratic model was chosen to explain acidity variation with yacon flour supplemented yogurt. It is observed that yogurts containing 1.
This accounts for the growing reduction of the acidity with increase in yacon flour concentration; and may also be related to the increased amount of TSS table 3 , since there is a strong inverse relation between TSS and acidity Results of apparent viscosity measurement of the yogurts. Yogurts with yacon presented a shear-thinning fluid behavior, i.
This reduced gumminess during intake The control yogurt presented a higher apparent viscosity than the yogurt with 1. This behavior is quite common in food fluids 28 since increase in temperature promotes a decrease in viscosity. This occurs because the movement of suspended particles increases As expected, when taking into account the lower apparent viscosity of yogurt with 1.
FOS and inulin are soluble dietary fibers capable of interacting with the aqueous portion of the yogurt. They are highly hygroscopic substances which act as food stabilizers because of their capability to form a more cohesive mesh, similar to gel 30 , thus changing system viscosity. Despite this, these products are not able to form a gel after heating and cooling processes at some concentrations Therefore, it is suggested that the FOS and inulin content in yogurts with 1.
Additionally, yogurt carbohydrate levels also have an influence on product apparent viscosity, and carbohydrate content also presented a quadratic effect due to yacon flour concentration, corroborating the quadratic regression model adjusted for apparent viscosity. Addition of yacon flour to yogurt leads to products with low fat and low caloric values. Yogurts supplemented with 2. They were capable of providing dietary fiber concentrations higher than the minimum recommended by Brazilian regulations.
It was not possible, however, to obtain yogurts considered source of FOS and inulin as expected. Further studies are needed in order to optimize the use of even greater yacon concentrations in food products given the notable benefits it can bring to consumers.
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Blood samples were collected at the end of depletion and repletion stages for determination of hemoglobin concentration and calculation of the relative biological value RBV. Iron deficiency is the most common and widespread nutritional disorder in the world, and is a public health problem in both industrialized and non-industrialized countries. Anemia is, in terms magnitude, the main problem of deficiency in the world, apparently without major geographic differentiations 1. Food fortification is a well recognized approach to overcome hidden hunger in many parts of the world, particularly in developing countries. Additionally, fortification is a method of controlling micronutrient deficiency as an intervention alternative mainly recommended for locations where high prevalence rates are found 2. Several condiments and foods, including sugar, soybeans, milk, oil, wheat flour and rice have been explored as potential vehicles for fortification in different country contexts.
Studies of chemical and enzymatic characteristics of Yacon Smallanthus sonchifolius and its flours. Due to the importance of studies on yacon related to health, its in natura pulp, in natura peel, pulp flour, and peel flour were chemically analyzed in terms of its centesimal composition, specific minerals, total dietary fiber and fractions, pH, total soluble solids, total titratable acidity, tannins, oxalic acid, and nitrate. The polyphenoloxidase and peroxidase enzymatic activities were evaluated for in natura pulp and peel only. Yacon pulp and peel flour presented average yield of 7.