Orientador: Prof. Dr. Flávio Faria de Moraes

Data da Defesa: 20/03/2015



THEORETICAL FOUNDATIONS Functional foods stand out for promotion and maintenance of health and wellbeing because they contain bioactive compounds, which contribute to food security and nutrition, and may reduce the risk of chronic degenerative diseases. Resistant starch (RS) has attracted great interest because it is not digested in the small intestine and is fermented by anaerobic bacteria in the colon, increasing the fecal mass, and preventing constipation, hemorrhoids and assisting in the dilution of toxic compounds, potential inducers of cancer cells. In addition, RS is associated with the decrease in the glycemic index of foods and can be used in the treatment of diabetic individuals, particularly with diabetes type 2. The development of functional food is a complex process which differs from the traditional product, requiring an integrated and innovative approach that involves several steps of developing a fundamental concept and its translation into an acceptable commercial new food ingredient, up to the evaluation of its efficacy and safety for use in humans. These procedures are important because they increase the reliability and form the basis for regulation of the product. Increase in resistant starch fraction by means of chemical and physical modifications of potato and maize starches has been documented in the literature. Considering that national production of cassava (Manihot esculenta) is about 35 million tons / year and its derivatives are widely consumed, the cassava starch (known as fecula in Brazil) is an interesting raw material for the development of a new food product with potentially functional characteristics. OBJECTIVES General Objectives Develop fully (beginning from the fundamental concept and going up to the application) a new food ingredient with potential functional characteristics, using cassava starch as the starting raw material. Specific Objectives  Establish the fundamental concept for a novel food ingredient with functional capabilities: Resistant Cassava Starch (RCS);  Transfer the fundamental concept to a model ingredient by modification of native cassava starch (commercial sweet cassava flour) through thermal-acid treatment;  Measure the efficiency of the technique applied in the transfer of the fundamental concept by determining in vitro the content of resistant starch in the model ingredient;  Characterize physicochemically the new ingredient (RCS) compared to native cassava starch;  Apply the RCS in the development of a product of wide consumption (fermented milk drink);  Study the influence of the addition of RCS in the rheological and sensory characteristics of the developed fermented milk drink. 10 METHODOLOGY This work comprehends the study of functional foods and its importance in human health, with regard to the development of resistant cassava starch (RCS) carried out on two levels: the theoretical or conceptual stage and the experimental development. On a theoretical level, the study sought to establish the steps for the development of this type of food, while the experimental level it involved the production of RCS with subsequent application of in vitro and in vivo characterization techniques and the development of a product. We analyzed the physical and chemical parameters of the RCS produced by a process of food grade citric acid treatment under heating, which has the property to increase the resistant starch content of the commercial sweet cassava starch. The characterization of the new ingredient was performed compared to the native starch, regarding chemical composition, resistant starch content, scanning electron microscopy, X-ray diffraction and infrared spectroscopy (FTIR), solubility, swelling power, water absorption capacity, viscoamylograph analysis and in vivo glycemic response. The viscoamylographic analysis was carried out in 6% (p/v, bs) starch suspensions, in a Brabender Viscograph (Brabender, Duisburg – Germany) equipped with a cartridge sensitivity of 700 cm·g, using the following parameters: paste initial temperature, initial viscosity at 95 ºC, final viscosity at 95 ºC, maximum viscosity, maximum viscosity temperature, final viscosity at 50 ºC. The X-ray diffraction analyses were performed with a Shimadzu XRD – 7000 equipment, with Cu Kα radiation, in a scanning time of 0.6 s. The diffraction angle scanning range was 10-80º (2q), using a generator with a voltage of 40 kV and an emitting current of 30 mA. The sample analysis was obtained on a Bruker FTIR spectrophotometer, model Vextex 70x, using KBr tablets. The spectrum range considered was 4,000 to 400 cm1 . After characterization, the new ingredient was applied in different concentrations (C control, without RCS; A1 0.5%, A2 1.5%) in the dairy beverage development to evaluate the influence of RCS addition. The formulation of the drinks was carried out by lactic acid fermentation of whole milk UHT (1 L), reconstituted whey powder (100: 1 g/L), sucrose (133.3 g/L) and a thickener (16 g/L) by the action of the microorganisms Lactobacillus acidophilus, Bifidobacterium lactis and Streptococcus thermophilus (400 mg/L - Rich Bio) at 45 °C for 6 hours. The mixture was kept under refrigeration at 4 °C for 24 hours and in the fermented medium it was added strawberry pulp (100 g/L) and a dye (0.01 g/L). The selected concentrations of RCS were added to the final product with subsequent homogenization. Sanitary hygienic conditions of the beverages were evaluated by microbiological analyzes before further characterization of the chemical composition, rheological properties, sensory profile and purchase intent. A test of acceptance was carried out using a hedonic scale of nine points, ranging from "dislike extremely" (1) to "liked very much" (9) by 112 untrained male and female judges for the color, taste and consistency. A purchase intent test with a three-point scale (1 being - certainly not buy and 3 - surely buy) was carried out too. The samples were coded, randomized and presented to the panelists at 5 °C in 50 ml plastic cups. For the rheological analysis of the formulations a Brookfield LV rheometer with concentric cylinders (spindle SC4-27) was used equipped with thermostatic bath for temperature control. Assays were performed in duplicate, at temperatures of 10 to 25 ° C. 11 RESULTS With the technique applied for the production of RCS, there was a significant increase in resistant starch content (~60 %) compared to the native starch (1.23 %). It was observed the emergence of cracks and superposed layers in the treated starch granules, decreased solubility, lower swelling power and capacity of water absorption. The native cassava starch viscoamylograph test showed a standard curve while RCS gave a line parallel to the time axis, since the starch modification took place inside the granules and the increase in resistant starch resulted in decreased absorption of water and consequent lower viscosity. The infrared RCS spectrum presented a new band at 1745 cm-1 , which was associated with the stretching vibration of the acetyl group, indicating ester linkages with the starch chains. Furthermore, there was a change in the difratometric pattern with the starch modification and RCS showed the characteristics of an amorphous substance. In the study of the glycemic response "in vivo" conducted with 15 Wistar male rats, the ARM gave higher results than the native starch in the times of 30, 60 and 90 min after ingestion. The results of the microbiological analysis for the formulated dairy beverages meet the provisions of current legislation and indicate good practice in the manufacturing process. All formulations contain the minimum protein content according to regulation and fall into the category of partially skimmed milk drink. The analysis of the rheological properties indicated for all samples that the apparent viscosity of the product decreases with increasing deformation rate, corresponding to the characteristic of a non-newtonian pseudoplastic fluid type. It has been found that the addition of resistant starch in the fermented dairy beverage did not significantly alter the consistency index of the product or the flow behavior index, for two temperatures evaluated. With regard to the sensory characteristics of the samples, analysis of variance showed no statistically significant difference (p <0.05) between formulation A1 (0,5 % ARM) and control (C) for any of the attributes tested, while formulation A2 (1,5 % ARM) was different from the other for the color, taste and consistency. The drink with the highest intention to purchase by the judges was the formulation A1. CONCLUSIONS The results of this study show that modification with citric acid and heating was effective for increasing the resistant starch content of native cassava starch. The product has cracked granules, small overlapping layers on the surface of the granules and diffraction characteristic of an amorphous substance. These data evidence the modification of the starch granules which undergone a large increase in resistant starch due to the crosslinking of the starch chains by the formation of starch citrate ester bonds. The increase in resistant starch content hinders the action of amylolytic enzymes to break down the glucosidic linkages of the modified amylose and amylopectin, preventing the breaking of these molecules. The good acceptance of the product applied in the dairy beverage formulation shows that the resistant cassava starch is a promising functional food ingredient. However, further studies are needed to better understand the real impact in the glucose metabolism and other physiological benefits associated with the consumption of resistant cassava starch.

KEY-WORDS Resistant starch, cassava starch, citric acid, heating, functional food, dairy beverage.


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