Desenvolvimento de kefir adicionado de luteína

Abstract

Lutein, a natural lipophilic yellow-orange dye, is a carotenoid with antioxidant capabilities and has been specifically linked to a reduced occurrence of cataracts and age-related macular degeneration. Furthermore, lutein can also be a significant ally in reducing oxidative stress and DNA damage, contributing to the prevention of various types of cancer. As lutein is not synthesized by the human body, it has to be supplied through food. To reach the minimum intake of 6 mg/day of lutein, you would need to eat 2 bowls of spinach or a bowl of kale salad a day, which makes it practically impossible for most people. The application of lutein as a functional ingredient in dairy products is an attractive option, to make lutein available in a tasty way and also be an option for those looking for foods with natural and healthier ingredients. Kefir stands out as a natural food with good nutritional quality and health benefits. Due to the presence of proteins and lipids in its composition, the addition of lutein to kefir becomes interesting since these biomolecules are excellent carriers of hydrophobic compounds. The aim of this study was to develop kefir with added lutein and evaluate the oxidative aspect of this bioactive dye over the storage period. In the production of kefir, pasteurized milk was supplemented with sucrose, lutein and yeast. After the fermentation process, curd breaking was carried out, and the product was packaged. The kefir had a composition of 3.13% protein, 2.78% fat, 82.20% moisture, 17.80% total solids, and 0.71% fat-free dry matter. The product's pH ranged between 4.32 and 4.35, and the titratable acidity varied between 0.81 to 0.99 g of lactic acid per 100 mL, meeting the acidity parameter determined by current regulations. The instrumental color analysis indicated that the kefir had a light color, and due to the initial positive values found for the chromatic coordinates a* and b*, the color approached the red and yellow chromaticity axes, respectively. Lutein did not interfere with the drink's water retention capacity. There was a decrease in apparent viscosity and a non-linear increase in shear stress, of both kefir. The addition of lutein to kefir significantly increased (p > 0.05) the total phenolic compound content, but these decreased over the storage period. Regarding in vitro antioxidant capacity, the addition of lutein also significantly increased (p > 0.05) the kefir samples's antioxidant activity, regardless of the method used (ABTS or DPPH radicals), with reductions over the shelf life. As for microbiological quality, none of the kefir samples showed coliform counts at 30 or 45 °C, meeting the criteria established by regulations. The count of filamentous fungi did not meet the minimum standard of 104 CFU/g. The initial count of lactic bacteria was around 107 CFU/g, complying with regulations, but they were not viable over the storage period. The kefir with added lutein showed good sensory acceptance during the storage period, with an overall acceptance score of 6.44 on the nine-point hedonic scale. Therefore, the results of this study are promising and encourage further investigations for obtaining and using lutein as an antioxidant ingredient in the food industry.