Effects of Harvest Time and Hydrodistillation Time on Yield, Composition, and Antioxidant Activity of Mint Essential Oil.

In this study, we assessed the effects of different harvest times (9 a.m., 1 p.m., and 5 p.m.) and hydrodistillation times (60, 90, and 120 min) on the yield, chemical composition, and antioxidant activity of the spearmint (Mentha spicata L.) essential oil (EO) sourced from the Amazon region. EO yield was ≥1.55% and was not significantly influenced (p ≥ 0.05) by the different harvest times and hydrodistillation times. Thirty-one different organic compounds were identified, of which menthol (91.56-95.68%), menthone (0.6-2.72%), and isomenthone (0.55-1.46%) were the major constituents. The highest menthol content in the EO was obtained from samples collected at 9 a.m., with a hydrodistillation time of 60-90 min, compared to other harvest and hydrodistillation times. This suggests that exposure to sun and light, which is greater at harvest times of 1 p.m. and 5 p.m., decreased the menthol content and altered the chemical composition of Mentha EO. Furthermore, the sample harvested at 9 a.m. and hydrodistilled for 60 min showed the highest antioxidant activity (61.67 equivalent mg of Trolox per g of EO), indicating that antioxidant activity is strongly affected by light exposure and the contact duration of the sample with boiling water during hydrodistillation.

Bioactive Natural Compounds and Antioxidant Activity of Essential Oils from Spice Plants: New Findings and Potential Applications.

Spice plants have a great influence on world history. For centuries, different civilizations have used them to condiment the foods of kings and nobles and applied them as embalming preservatives, perfumes, cosmetics, and medicines in different regions of the world. In general, these plants have formed the basis of traditional medicine and some of their derived substances have been utilized to treat different human diseases. Essential oils (EOs) obtained from these plants have been also used as therapeutic agents and have shown supportive uses in remedial practices. The discovery and development of bioactive compounds from these natural products, based on their traditional uses, play an important role in developing the scientific evidence of their potential pharmaceutical, cosmetic, and food applications. In the present review, using recent studies, we exhibit a general overview of the main aspects related to the importance of spice plants widely used in traditional medicine: Cinnamomumzeylanicum (true cinnamon), Menthapiperita (peppermint), Ocimumbasilicum (basil), Origanumvulgare (oregano), Piper nigrum (black pepper), Rosmarinus officinalis (rosemary), and Thymus vulgaris (thyme); and we discuss new findings of the bioactive compounds obtained from their EOs, their potential applications, as well as their molecular mechanisms of action, focusing on their antioxidant activity. We also exhibit the main in vitro methods applied to determine the antioxidant activities of these natural products.

Fluid-dynamic behavior of flaxseed fluidized and spouted bed / Comportamento fluidodinâmico de sementes de linhaça em leito fluidizado e jorro

ABSTRACT: Processing of particles in a moving bed, such as a fluidized bed or a spouting bed, is commonly used in the operations of drying, coating, and granulation of particulate systems. This process has applications in the chemical, pharmaceutical and, presently, agronomical industries, especially for seed treatment/coating. This research aimed to analyze the fluid-dynamic behavior of fluidized and spouting beds with different air temperatures and loads of flaxseeds (Linum usitatissimum L.), with estimates of the fluid-dynamic parameters correlated to each process. The parameters were compared with the values obtained from classical correlations in the literature, with indications of associated percentages of deviation. Influence of fluid dynamics on the physiological quality of seeds was assessed by germination tests and the germination speed index. An analysis of the results indicated that seed processing was adequate for processing in dynamically active beds; however, temperatures above 50ºC in both beds caused significant reductions in the physiological quality of the seeds. Processing in a fluidized bed presented a smaller reduction of the physiological properties of the flaxseed.

RESUMO: O processamento de partículas em leitos móveis, como o leito fluidizado e o leito de jorro, são comumente empregados em secagem, recobrimento e granulação de sistemas particulados, com aplicações nas indústrias química, farmacêutica, e atualmente na agronômica, em especial no tratamento/revestimento de sementes. Este trabalho tem como objetivo analisar o comportamento fluidodinâmico, em leito fluidizado e jorro, das sementes de linhaça (Linum usitatissimum L.), para diferentes cargas de sementes. Obter as curvas fluidodinâmicas dos leitos: fluidizado e de jorro, estimando os parâmetros fluidodinâmicos correlacionados a cada processo. No leito fluidizado foram determinados: a velocidade de mínima fluidização, queda de pressão na máxima e mínima fluidização, expansão do leito e, porosidade de mínima fluidização e, para o leito de jorro, foram estimados a velocidade de mínimo jorro, queda de pressão máxima e queda de pressão no mínimo jorro. Estes parâmetros foram comparados com os valores obtidos de correlações clássicas da literatura, sendo observados baixos desvios percentuais para os mesmos. Avaliou-se a influência da fluidodinâmica sobre a qualidade fisiológica das sementes através dos testes da germinação e do índice de velocidade de germinação.