Essential oils from Citrus x aurantium and Citrus x latifolia (Rutaceae) have anesthetic activity and are effective in reducing ion loss in silver catfish ( Rhamdia quelen )

The impact of essential oils on the qualitative properties, release profile, and stimuli-responsiveness of active food packaging nanocomposites

Food industries attempt to introduce a new food packaging by blending essential oils (EOs) into the polymeric matrix as an active packaging, which has great ability to preserve the quality of food and increase its shelf life by releasing active compounds within storage. The main point in designing the active packaging is controlled-release of active substances for their enhanced activity. Biopolymers are functional substances, which suggest structural integrity to sense external stimuli like temperature, pH, or ionic strength. The controlled release of EOs from active packaging and their stimuli-responsive properties can be very important for practical applications of these novel biocomposites. EOs can affect the uniformity of the polymeric matrix and physical and structural characteristics of the composites, such as moisture content, solubility in water, water vapor transmission rate, elongation at break, and tensile strength. To measure the ingredients of EOs and their migration from food packaging, chromatographic methods can be used. A head-space-solid phase micro-extraction coupled to gas chromatography (HS-SPME-GC-MS) technique is as a good process for evaluating the release of Eos. Therefore, the aims of this review were to evaluate the qualitative characteristics, release profile, and stimuli-responsiveness of active and smart food packaging nanocomposites loaded with essential oils and developing such multi-faceted packaging for advanced applications.

An Integrated biomarker approach for explaining the potency of exogenous glucose on transportation induced stress in Labeo rohita fingerlings

Transportation of fish seed is a complex phenomenon associated with multiple kinds of stressors that simultaneously affect the fish in a confined environment, causing stress and mortality. The present study investigated the stress-relieving effect of exogenous glucose as a water additive in different concentrations (0.1, 0.2, 0.3, and 0.4%) during simulated transportation (12 h) of L. rohita fingerlings. The integrated biomarker response (IBR) index is a holistic tool to determine the optimum dose of exogenous glucose for mitigating transportation stress in fish. Based on selected biomarkers related to the stress hormone, serum biochemistry, oxidative stress, and HSP70 mRNA expression, the IBR index is calculated for each treatment and control group. The result showed a significant change in the level of stress hormone cortisol, enzymes (SGPT, LDH, MDH, SOD, CAT) and metabolites (serum glucose, triglyceride, creatinine) along with an upregulation in liver HSP70 mRNA expression. IBR index suggests that 0.2% glucose exhibited the lowest multi-biomarker stress response in comparison to other treatments and control. Therefore, the use of 0.2% glucose as a water additive will provide a solution to transportation induced stress in L. rohita fingerling and will underwrite the success of grow-out fish culture in days to come.

Essential Oils as Stress-Reducing Agents for Fish Aquaculture: A Review

In fish, stressful events initiate a hormone cascade along the hypothalamus-pituitary-interrenal and hypothalamus-sympathetic-chromaffin (HSC) axis to evoke several physiological reactions in order to orchestrate and maintain homeostasis. Several biotic and abiotic factors, as well as aquaculture procedures (handling, transport, or stocking density), activated stress system inducing negative effects on different physiological processes in fish (growth, reproduction, and immunity). In order to reduce these consequences, the use of essential oils (EOs) derived from plants has been the focus of aquaculture studies due to their diverse properties (e.g., anesthetic, antioxidant, and antimicrobial), which have been shown to reduce biochemical and endocrine alterations and, consequently, to improve the welfare status. Recently, several studies have shown that biogenic compounds isolated from different EOs present excellent biological activities, as well as the nanoencapsulated form of these EOs may potentiate their effects. Overall, EOs presented less side effects than synthetic compounds, but their stress-reducing efficacy is related to their chemical composition, concentration or chemotype used. In addition, their species-specific actions must be clearly established since they can act as stressors by themselves if their concentrations and chemotypes used are not suitable. For this reason, it is necessary to assess the effect of these natural compound mixtures in different fish species, from marine to freshwater, in order to find the ideal concentration range and the way for their administration to obtain the desired biological activity, without any undesired side effects. In this review, the main findings regarding the use of different EOs as stress reducers will be presented to highlight the most important issues related to their use to improve fish welfare in aquaculture.

Stress-reducing and anesthetic effects of the essential oils of Aloysia triphylla and Lippia alba on Serrasalmus eigenmanni (Characiformes: Serrasalmidae)

ABSTRACT Anesthetic effect of Aloysia triphylla and Lippia alba essential oils (EOs) in the Amazonian fish Serrasalmus eigenmanni was evaluated. The fish were placed in aquaria containing A. triphylla or L. alba EOs (25 to 200 µL L-1). Then, fish were transferred to aquaria containing EO-free water to evaluate their recovery time. In another experiment, fish were transferred to aquaria containing A. triphylla or L. alba EOs (3 to 10 µL L-1) and swimming behavior was analyzed for up to 240 min of exposure. Water samples were collected at 0 and 240 min and blood samples were collected at 240 min. Tested concentrations induced all stages of anesthesia, except 25 µL L-1 A. triphylla EO and 50 µL L-1 L. alba EO, which only induced sedation. Prolonged exposure to both EOs reduced swimming time compared to the control at all evaluated times. The fish exposed to 3 µL L-1 A. triphylla EO showed a lower net K+ efflux compared to ethanol-exposed fish; in those exposed to 5 µL L-1, ammonia excretion was reduced. The blood parameters did not show significant differences between treatments. In conclusion, both EOs can be used as anesthetics and sedatives for transport of S. eigenmanni.