RESUMO Neste trabalho foi avaliada a pós-acidificação, a estabilidade das antocianinas e da atividade antioxidante em iogurtes e leites fermentados de açaí durante 28 dias de armazenamento refrigerado. Para determinação da pós-acidificação, assim como da estabilidade das propriedades funcionais dos iogurtes (IA) e leites fermentados (LFA) de açaí, os produtos armazenados a 4 ºC, foram avaliados no dia 0 e a cada 7 dias, quanto ao pH, acidez titulável em ácido lático, cor instrumental, antocianinas e atividade antioxidante pelo método do radical livre DPPH. A acidificação de ambas as matrizes alimentares foram mais evidentes entre os dias 0 e 7 de avaliação. Os IA apesentaram redução no parâmetro L*, enquanto que as cromaticidade a* e b* dos IA e LFA aumentaram seus valores, à medida que o teor de polpa de açaí foi aumentado, entretanto considerando o período de avaliação, verificou-se aumento de L* e b* relacionando-se as degradações nas antocianinas. As antocianinas, assim como a atividade antioxidante dos IA e LFA mostraram aumento em seus valores conforme os teores de polpa foram aumentados, porém reduziram suas concentrações ao fim do período de armazenamento. Os IA e LFA, podem ser considerados excelentes fontes de substâncias antioxidantes, sendo alternativa a indivíduos não habituados ao consumo de frutas e legumes.

ABSTRACT This study evaluated the post-acidification, stability of anthocyanins and antioxidant activity in açai yogurts and fermented milks for 28 days of cold storage. For the determination of post-acidification and stability of the functional properties of açai yogurt (IA) and fermented milks (LFA), products stored at 4°C were evaluated on day 0 and every 7 days for pH, titratable acidity in lactic acid, instrumental color, anthocyanins and antioxidant activity by the DPPH free radical method. Acidification of both food matrixes was more evident between days 0 and 7 of evaluation. IA presented reduction in parameter L *, while chromaticity a * and b * of IA and LFA increased as the Açai pulp content increased; however, considering the evaluation period, it was found increase in L * and b * relating to anthocyanin degradation. Anthocyanins, as well as the antioxidant activity of IA and LFA, showed an increase in their values as the pulp content increased, but their concentrations reduced at the end of the storage period. IA and LFA can be considered excellent sources of antioxidants, being alternative to individuals not used to the consumption of fruits and vegetables.

Abstract Despite recent advances in food production technology, food-borne diseases (FBD) remain a challenging public health concern. In several countries, including Brazil, Clostridium perfringens is among the five main causative agents of food-borne diseases. The present study determines antimicrobial activities of essential oils of six condiments commonly used in Brazil, viz., Ocimum basilicum L. (basil), Rosmarinus officinalis L. (rosemary), Origanum majorana L. (marjoram), Mentha × piperita L. var. Piperita (peppermint), Thymus vulgaris L. (thyme) and Pimpinella anisum L. (anise) against C. perfringens strain A. Chemical compositions of the oils were determined by GC–MS (gas chromatography–mass spectrometry). The identities of the isolated compounds were established from the respective Kováts indices, and a comparison of mass spectral data was made with those reported earlier. The antibacterial activity was assessed from minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) using the microdilution method. Minimum inhibitory concentration values were 1.25 mg mL-1 for thyme, 5.0 mg mL-1 for basil and marjoram, and 10 mg mL-1 for rosemary, peppermint and anise. All oils showed bactericidal activity at their minimum inhibitory concentration, except anise oil, which was only bacteriostatic. The use of essential oils from these common spices might serve as an alternative to the use of chemical preservatives in the control and inactivation of pathogens in commercially produced food systems.

The total phenolic and flavonoid content, color, and antioxidant activity were evaluated from ten honey samples from Apis mellifera L. collected from Roraima State, Brazil. The total phenolic content was determined using the Folin-Ciocalteu reagent and ranged from 250 to 548 mg gallic acid kg-1 of honey. The total flavonoid content was obtained using two methods: total flavones/flavonols were determined with aluminum chloride, and flavonones/dihydroflavonols were determined with 2,4-dinitrophenylhydrazine. The results ranged from 9 to 48.6 mg of quercetine kg-1 of honey and 1805 to 2606 mg of pinocembrin kg-1 of honey, respectively. Antioxidant activity was measured with 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavengers, and the results of the IC50 ranged from 3.17 to 8.79 mg/mL. Statistical analysis demonstrated positive correlations between color intensity, flavone and flavonol content, and phenolic content and negative correlations with antioxidant capacity.

The volatile oils of Dalbergia frutescens were obtained by hydrodistillation on a Clevenger-modified apparatus for every month of one year and assessed on GC/MS and GC/FID detectors for qualitative and quantitative analyses. The influence on content of volatile oils was directly proportional to the environmental variables, temperature and cloudiness, and inversely proportional to precipitation. Among the volatile compounds detected, linalool, β-damascenone, α-ionone, geranyl acetone and β-ionone were the main components, of which β-damascenone and β-ionone were found at the highest concentrations.