Orientador: Makoto Matsushita

Data da Defesa: 27/02/2020


INTRODUCTION. Foods that provide health benefits represent a trend in the current consumer market. Teff (Eragrostis tef) is a cereal native to Ethiopia that is becoming globallypopular due to its nutritional excellence. Due to the diminutive grain size, teff flour is typically prepared from whole grains resulting in a flour that is rich in fiber, minerals, and polyphenols. Phenolic compounds constitute a heterogeneous family of chemical compounds extensively studied due to their diverse health benefits. However, the quantification of these phytochemicals requires an adequate extraction methodology for each food matrix. Experimental designs, such as simplex-centroid, have contributed to the optimization of extraction methodologies and efficient techniques with low environmental impact, such as ultrasound (UAE) and ultrahomogenization (HAE), have been commonly applied. In addition to high nutritional quality, teff flour does not contain gluten, a complex mixture of storage proteins present in wheat, barley, and rye. The popularization of the gluten-free diet as a healthier option along with the
increasing incidence of gluten-associated disorders are driving an increasing number of consumers to opt for a diet free of this protein as a lifestyle choice. However, the technological, nutritional and sensory quality of gluten-free products has been the main challenge for food technology. The use of alternative grains such as teff has been proposed to improve the quality of these products. In addition, the yacon (Smallanthus sonchifolius) can be considered another healthy option for gluten-free products due to their high content of inulin and fructooligosaccharides that act as dietary fibers promoting several benefits to the body. Descriptive sensory analysis, such as the flash profile (FP), is commonly used in industry to describe sensory characteristics of products under development and the common dimension analysis (ComDim) presents as a powerful tool for statistical analysis of the data generated by FP. OBJECTIVES. The first objective of this study was to optimize the solvent composition for the extraction of phenolic compounds from whole teff grains using a simplex-centroid mixture design and compare extraction efficiency for UAE and HAE. The second objective was to apply the simplex-centroid design to develop gluten-free bread (GFB) containing teff flour (TF) and yacon (YF) and evaluate the acceptance and descriptive sensory characteristics of the products developed using FP and ComDim analysis.
MATERIAL AND METHODS. To investigate the effect of the solvent system in the extraction of phenolic compounds from teff grains, a simplex-centroid mixture design with water, ethanol, and methanol was used. The experiments of solid-liquid extraction were carried out by HAE and UAE. The total phenolic content (TPC) was used to obtain response surfaces to analyze the extraction as a function of solvent composition. After optimization and validation, the total flavonoid content and the antioxidant capacity (estimated by the methods of DPPH, ABTS and FRAP) of the extracts were also evaluated and the quantitative profile of polyphenols extracted was determined by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-TQD). For the development of GFB enriched with teff and yacon flour, a simplex-centroid mixture design was also used. Different proportions of the gluten-free mix (52% of rice flour; 36% of potato starch; and 12% cassava starch), teff and yacon were studied, totaling nine different formulations. Sensory acceptance data for color, aroma, flavor, texture and global acceptance were used to optimize the formulations according to the components of the mixture. The descriptive sensory characteristics of the three optimized formulations were performed by FP and the data were evaluated using the ComDim analysis.
RESULTS AND DISCUSSION. According to the optimization, the maximum response was estimated at solvent ratios of 51:40:9 and 49:26:25 (water/ethanol/methanol, v/v/v) for HAE and UAE, respectively. Under optimal conditions, the extraction technique did not significantly influence the TPC extracted (213.1 ± 19.65 mg GAE 100 g-1 by HAE and 209.92 ± 6.12 mg GAE 100 g-1 by UAE), but the total flavonoid content and the antioxidant capacity were significantly higher when UAE was used. The phenolic acids p-coumaric and protocatechuic and the flavonoids quercetin, rutin, and myricetin were the main polyphenols extracted. Glutenfree bread developed with teff and yacon flour showed good acceptance among the assessors. The results showed that the addition of teff and yacon flour (up to 35%) maintained the sensory attributes. Optimal formulations were obtained to maximize the addition of teff (69.4% glutenfree mix and 19.5% teff flour), maximize the addition of yacon (78.2% gluten-free mix and 21.8% yacon) and minimize the addition of gluten-free mix (63.5% gluten-free mix, 20.1% teff and 16.4% yacon). In the descriptive analysis, the formulation enriched with yacon flour was described by the white color, aroma, taste of white flour, softness and sour aroma, whereas the bread enriched with teff and yacon flour was described by the brown color, rougher and aerated texture, wholemeal flour aroma and bitter taste.

CONCLUSIONS. The simplex-centroid design proved to be an efficient tool for the optimization of the extraction methodology of phenolic compounds from teff grains and to assist the food industry to develop new products. Teff contains a considerable amount of phenolic and flavonoid compounds with potential antioxidants, being suitable to improve the nutritional quality of food products. This study also highlights the potential of teff and yacon flour for the production of gluten-free products, specifically bread, proving to be a good option for consumers with gluten-associated disorders or consumers to opt for a gluten-free diet as a lifestyle choice.
KEYWORDS. Mixture design; UPLC-TQD mass spectrometer; polyphenols; flash profile; common dimension analysis; sensometrics.


Artigos Publicados Vinculados a Tese: