Orientador: Prof. Dr. Makoto Matsushita

 Data da Defesa: 28/08/2017



INTRODUCTION. Goat's milk is a food in excellence for its nutritional claims, motivated mainly by its protein and lipid composition of great interest for individuals allergic or intolerant to cow's milk. Many researches are being applied in the development of products that use this raw material, giving goat's milk functional properties. Another food widely investigated as its functionalities is chia (Salvia hispanica L.), an oleaginosa with high content of poliunsaturated fatty acids, especially omega-3, in addition to its protein supply and composition of fibers and minerals. Since it is a seed with many benefits, several applications with chia were evidenced in bakery products, however, are still small the contributions of its coproducts (flour of chia, flour of chia partially defatted and chia mucilage) in the area of dairy products, there is interest in applying them in food formulations of added value. Among the milk products, the sweet milk, also called "dulce de leche" and "milk candy" is a widely consumed product in Latin America, including Argentina and Brazil. Although it is a concentrated milk widespread, its manufacturing technology, did not face many changes of process over the years, and basically the same raw materials are used in its preparation, motivating the search for new ingredients such as goat's milk and flour of chia, which can allow innovative applications and a product of higher nutritional value. As for the ice cream, the searches are centered on the use of substitutes of fat that allow technological characteristics and sensory similar to conventional products of high caloric content available in the market. The great challenge is to find ingredients that simulate these properties and the gums extracted from seeds are an alternative to be investigated. The chia has around 6 % of fibers, which when they are hydrated in water, form a ooze rich in polysaccharides, even when used small proportions of seed. This fact is of great interest for extraction of starch and applying as a surrogate of greasy in cream, with a view to its functions thickening, gelling and stabilizer. AIMS. The objective of the present work was to use by-products of chia seeds in dairy products with goat's milk, analyzing them in their technological, instrumental and nutritional characteristics. In the sweet milk, the addition of the whole chia flour was proposed and partially degreased, supposing the corn starch, commonly used as thickening agent. In the sweet milk, it was proposed that the addition of the flour of chia fully and partially defatted by supplementing the corn starch in a proportion of 1 g/L commonly used as a thickening agent in two different age of concentration of soluble solids (72 and 78 ºB). In ice cream, we sought to replace in different proportions of concentration of vegetable shortening by mucilage of chia (50, 75 and 100% of replacement), in association with the locust beam gum as a substitute of stabilizer and industrial emulsifier (50, 75 and 100% of replacement) at different times of maturation of the syrup (12.18 and 24 h). MATERIAL AND METHODS. For the development of the ice cream, the chia mucilage was previously obtained, where the conditions of the extraction process were stipulated in: chia/water ratio: 1/40, pH: 8.0, extraction temperature: 80 ºC; Stirring time: 2 h. To separate the mucilage (supernatant) from the seeds (precipitate) the centrifugation procedure was adopted, under the following conditions: temperature: 20 ºC; speed of rotation: 2,600 rpm; time: 20 min. Thewet mucilage was evaluated as the proximate composition and income and for comparison purposes a sample was lyophilized and evaluated for yield. The formulations of ice cream were drawn up after tests on a pilot scale in order to determine the conditions and concentrations of the ingredients to be tested. With this preliminary study, it was elaborated a complete factorial design (CFD, 2 3 ) to investigate the influence of the variables: x1: locust bean gum (LBG); x2: mucilage of chia (MC); and x3: base maturation time (TMC), on the characteristics of compressive strength (g), overrun (%), melt rate (g/min) and energy value (Kcal/100 g). Some other analyses were performed in this study as follows: characterisation of goat milk (centesimal composition, acidity, defatted dry extract and density), chia mucilage characterisation (centesimal composition and extraction yield) and characterisation of ice cream formulations (centesimal composition, total solids and colour and rheological parameters).The variables x1 and x2 were used in substitution (50, 75 and 10 100 %) for the stabilizer/emulsifier and the hydrogenated vegetable fat respectively, and the variable x3 stipulated in 12, 18 and 24 h the planning totaled 11 tests with 3 central points and additionally we chose to maintain 3 more experiments with different conditions than those studied in the PFC (23 ). The analysis of physico-chemical characterization of goat's milk, mucilage of humid chia and ice cream formulations, as well as the color parameters for the product developed were also performed. For the sweet milk, the initial tests were carried out to indicate the best conditions of use of the flour of chia and the processing of the product, and these data were used to compose the delineation of 6 treatments, which are designed with 3 thickener agents at 1 g/L concentration, to be mentioned: whole chia flour (FCI), partially defatted chia flour (FCPD) and corn starch (AM), which were evaluated in two concentration ranges (72 and 78 ºB). The application of these components was used to evaluate the technological characteristics (instrumental analysis, centesimal composition and sensory analysis) and nutritional characteristics (composition of fatty acids and nutritional quality index of the lipid fraction) of dulce de leche. RESULTS AND DISCUSSION. Regarding the mucilage of chia used in the preparation of the ice cream, there was high water content (99,66 g/100 g) and between the solutes of greater proportion are the total carbohydrates (0,19 g/100 g), responsible for the training of the mucilage net. was a reduction in the yield of the mucilage after freeze-drying, observing the need for more detailed studies on the separation conditions of the mucilage of the chia seeds in order to obtain higher rates of yield. As for ice cream, the addition of MC decreased the lipid content by 3.10 g/100 g compared to standard treatment (ST), promoting the reduction of total energy of 11.79 Kcal/100 g. The increase in the proportion of LBG increased the moisture content of the ice cream and when this variable remained in association as TMC, changes in apparent viscosity behavior were observed. The mix became thicker, reducing overrun, probably due to difficulties in the rate of air entrainment during the beating and freezing, preventing the formation and stabilization of air cells. The ice creams showed as non-newtonian fluids with pseudoplastic flow, as the flow behavior index (n) was lower than 1 in all treatments. They also behaved like thixotropic fluids, because, when analyzed under a constant shear rate, the apparent viscosity decreased with time. The TMC also had a positive effect on the compression force as the variable increased. The major influence of TMC was for treatments with higher concentration of LBG (T8), increasing almost 4 times the values of the compression force alone (1.127,25 g). However, the combination of the three variables (LBG, MC and TMC) at the higher levels reduced the melt rate, which may be related to the need for greater heat transfer to melt the ice cream in high viscosity systems. Treatments, the initial melting was observed from 25 min, with higher melt flow in the final times (80-90 min). As for the color parameters, there was a tendency to increase the luminosity according to the reduction in the hydrogenated vegetable fat content, being able to be related to the yellow color of the hydrogenated vegetable fat and with the transparent aspect of the gel formed by the exudation of the seeds of chia, which, because of its high moisture content, contributed to the dispersion of the solid particles and to increase the light reflectance in the tests with higher MC presence. For the dulce de leche, the results indicated a higher moisture content in the tests with addition of FCI and FCPD With a higher concentration (78 ºB) when compared to the treatment with AM at 72 ºB, a fact that can be explained by the high fiber content found in chia flour, as reported by other authors in studies of characterization of this seed. The ash and protein contents remained slightly higher in the FPDC assays. For the total lipids, a higher concentration of concentrated milk at 78 °B was observed and added with chia flour, especially in the whole form. These results expressed excellent nutritional properties, with an increase in the polyunsaturated fatty acids levels, which remained higher in the two concentration ranges studied especially by the increase of the alpha-linolenic acid (omega-3) in the treatment with FCI when compared to the others (FCPD and AM). This simultaneous increase of 5.75 and 4.70 times the value of omega-3 in relation to sweet corn with corn starch gave a reduction in the n-6/ n-3 ratio by almost 6 times in the T3 treatment. Atherogenic index (IAT) and thrombogenic index (IT), the added treatments of FCI and FCPD also presented reduced values when compared to treatments with corn starch. These results are associated with the higher concentration of the alpha- 11 linolenic acid, which has superior antithrombogenic effect To omega-6 fatty acids. The ratio of hypocholesterolemic and hypercholesterolemic fatty acids (H/H) remained below 1.0 for all treatments, being slightly higher in milk added with FCI and FCPD. The low value of H/H is influenced by the high content of myristic (14:0) and palmitic (16:0) acids, which represent more than 55% of the total saturated fatty acids in milk sweetening treatments. Similarly, treatments with chia flour presented lower value for total energy, and the substitution of corn starch for partially defatted chia flour reduced by up to 14 Kcal/100g (T5). For the evaluated color parameters, the dulce de leche presented dark shade with lightness below 50 and Chroma values indicative of more intense color. When compared to corn starch treatments the color difference (ΔE*) was perceptible, and color distinctions were also identified during the sensorial analysis. The compression force of sweet milk was influenced by the type of thickening agent and concentration range, lower values of instrumental texture to the treatments with flour of chia to 72 b. These results were also applicants in sensory analysis, where the judges attributed higher means of acceptance and purchase intention for the sweet milk with lower concentration range. In all of the attributes analyzed, the index of acceptability was greater than 70% in 6 treatments. In the work developed with the byproducts of chia, excellent technological characteristics of dairy products with goat's milk were studied. In the ice cream, the mucilage of chia when lyophilized, presented reduced yield, being important to look for alternatives to try to optimize the separation conditions of the gel of the seeds. The different characteristics of the ice cream treatments were dependent on the studied variables. The increase in LBG, MC and MCT concentration increased the moisture content, conditioning the higher hydration of the proteins during the maturation stage, promoting the thickening of the mix. The increase in apparent viscosity also influenced the low overrun, an increase in instrumental time, especially when the level of LBG and TMC maximum. The TMC and the LBG reduced the melting of the ice cream according to the increase of these variables. MC alone appears to have contributed to the increase In the proportions of overrun and reduction of firmness at 1.531,16 g, , showing itself as a good substitute for the technological characteristics of fat, besides reducing the total lipid content by more than 50% and consequently the energy value. The addition of only 1 g / L of chia flour allowed the development of sweetened milk with an increase of mono and polyunsaturated fatty acids, mainly omega-3, reducing the n-6 / n-3 ratio , The atherogenic and thrombogenic index and the energy value. The treatments with FCI and FCPD also had a higher moisture content, with lower compressive strength in the instrumental texture analysis. Also, treatments concentrated at 72 ºB considered to be of better acceptance by consumers, with an acceptability index of more than 70% in all The evaluated attributes. Key words: Goat milk; Ice cream; Dulce de Leche; Mucilage; Chia Flour


Artigos Publicados Vinculados a Tese:

 https://doi.org/ 10.1590/1678-457x.22017
https://doi.org/ 10.1007/s13197-018-3344-2