RESUMO: A descoberta de novos aditivos naturais a partir de resíduos agroindustriais é considerada um importante tópico de pesquisa. Este estudo teve como objetivo investigar a viabilidade da extração assistida por ultrassom (EAU) de compostos antioxidantes do estigma do milho (EM) e o efeito de variáveis independentes (tempo e relação sólido-solvente) e sua interação na extração de EM. Os resultados indicaram que a EUA aumenta a atividade antioxidante e reduz o tempo de extração em 67%. Condições otimizadas para a extração simultânea de antioxidantes e polifenóis do EM foram obtidas com 5 min e uma relação sólido-solvente de 0,05 g mL-1. O extrato de EM obtido pela EUA foi caracterizado por ESI-ToF-MS e 27 fitoquímicos foram encontrados. O extrato apresentou atividades antifúngicas e antibacterianas promissoras contra 23 dos micro-organismos estudados. Portanto, o extrato de EM obtido pela extração assistida por ultrassom pode ser utilizado como fonte de compostos bioativos e antimicrobianos para uso como ingrediente funcional na indústria alimentícia e farmacêutica.

ABSTRACT: The discovery of new natural additives from agro-industrial waste is considered an important research topic. This study investigated the feasibility of ultrasound-assisted extraction (UAE) of antioxidant compounds from corn stigma (CS) and the effect of independent variables (time and solid-solvent ratio) and their interaction in the extraction of CS. Results indicated that the UAE method increases the antioxidant activity and reduces the extraction time by 67%. Optimized conditions for the simultaneous extraction of antioxidants and polyphenols from CS were obtained using 5 min and a solid-solvent ratio of 0.05 g mL-1. The CS extract obtained by UAE was characterized by ESI-ToF-MS and 27 phytochemicals were reported. The extract showed promising antifungal and antibacterial activities against 23 of the studied microorganisms. Therefore, the CS extract obtained by the UAE can be used as a source of bioactive and antimicrobial compounds for use as a functional ingredient in the food and pharmaceutical industry.

Abstract Biosurfactants have many advantages over synthetic surfactants but have higher production costs. Identifying microorganisms with high production capacities for these molecules and optimizing their growth conditions can reduce cost. The present work aimed to isolate and identify a fungus with high biosurfactant production capacity, optimize its growth conditions in a low cost culture medium, and characterize the chemical structure of the biosurfactant molecule. The fungal strain UFSM-BAS-01 was isolated from soil contaminated with hydrocarbons and identified as Fusarium fujikuroi. To optimize biosurfactant production, a Plackett–Burman design and a central composite rotational design were used. The variables evaluated were pH, incubation period, temperature, agitation and amount of inoculum in a liquid medium containing glucose. The partial structure of the biosurfactant molecule was identified by nuclear magnetic resonance spectrometry. F. fujikuroi reduced surface tension from 72 to 20 mN m−1 under the optimized conditions of pH 5.0, 37 °C and 7 days of incubation with 190 rpm agitation. The partial identification of the structure of the biosurfactant demonstrated the presence of an α,β-trehalose. The present study is the first report of the biosynthesis of this compound by F. fujikuroi, suggesting that the biosurfactant produced belongs to the class of trehalolipids.