Osmotic dehydration and ultrasound are pretreatments used in order to reduce costs and processing time in the drying of food. We investigated the effect of the ultrasonic bath and an ultrasonic probe in osmotic solution, as a pretreatment of the drying process in an oven, for beet snacks. Different conditions of pretreatments (TP: ultrasonic probe treatment; TB: ultrasonic bath treatment) were performed and analyzed for water loss (WL) and solid gain (SG). After the snacks were ready, we evaluated the drying kinetics, aw, Brix, color, texture, and anthocyanin content. No difference was observed between treatments for SG and WL. The pretreatments TP5, TP10 and TB20 decreased by 22.2% the drying time in the oven. Regarding the snacks, there was no difference in texture. The colors of TP5, TP10, and TB10 were similar to the control, as well as the aw value of the TP5 and TP10. The TP5 had the highest anthocyanin content. The use of ultrasound probe in osmotic solution for 5 min, as a predrying treatment, is a viable technology as it reduces pretreatment and drying time without impairing the quality of the final product.
Practical applications
The use of ultrasound as a pretreatment in the drying of fruits reduces the drying time. Drying is an important process in obtaining new products, in addition to increasing shelf‐life.
This study aimed to compare the herbicidal activity of solid formulas obtained by spray drying with conventional liquid formulas containing biomolecules produced by submerged cultivation of the fungus Diaporthe sp. in a stirred-tank bioreactor. The solid formula presented the highest phytotoxicity on plant control (96.7%) and the phytotoxicity was directly related to the concentration of fermented broth in the formula. The use of adjuvant improved the efficiency of the bioherbicide. Dry matters of treatments were lower than the control and this was correlated with an increase in oxidative stress, since the activity of the antioxidant enzymes such as superoxide dismutase and guaiacol peroxidase increased in the treatment with a high level of phytotoxicity. Spray drying technology is a promising tool to concentrate bioherbicide without the loss of bioactive compounds since one of the major challenges in the production of bioherbicides is the low concentration of active ingredients in the fermented broth.
BACKGROUND: Ultrasound (US) treatment was applied to increase the production of ⊎-1,3-glucanase and chitinase by Beauveria bassiana (IBCB 66) cultivated in submerged fermentation. Application of US at different growth stages, US power outputs, time of ultrasonication, and duty cycles were the parameters evaluated. RESULTS: The best strategy comprised ultrasonication during 5 min at 24 h of fermentation with a power output of 195 W (fixed frequency of 24 kHz) and a duty cycle of 0.5 s.s −1 (0.5 s ON, 0.5 s OFF). The US treatment resulted in a production increase of 46% for ⊎-1,3-glucanase and 42% for chitinase compared to the non-sonicated control. Fragmentations of the mycelia in the sonicated samples were observed in Scanning Electron Microscopy (SEM) micrographs after the US application, supporting the idea of a better release of enzymes to outside the cell. CONCLUSION: Ultrasound-assisted fermentation was a promising tool to increase the production of ⊎-1,3-glucanase and chitinase by Beauveria bassiana (IBCB 66). The combination of US parameters showed to be decisive in obtaining higher enzyme production when compared to the control non-sonicated experiment. Therefore, this work brings a significant contribution to the field of stimulation of bioprocesses with ultrasound since it shows a strategy to obtain higher enzyme production when compared to traditional fermentation.
The occurrence of several weeds in crops of high economic value directly affects grain yield. This scenario led to the mass investigation of chemical products that circumvent these adversities and provide control potential. Nonetheless, the excessive application of chemical herbicides has generated significant concerns about the environment. Accordingly, the adoption of alternative practices, such as the application of microbial metabolites, emerges as strategic control actions, having a sustainability bias and allowing the reduction of risks of human and animal contamination. Appropriately, this study proposed to conduct a microbial prospection of microorganisms capable of producing secondary metabolites to inhibit growth and generate phytotoxicity in weeds. Furthermore, to increase the herbicidal activity, different strategies were evaluated involving microbial co-cultivation and ultrasound-assisted extraction after fermentation. Accordingly, 63 microorganisms were isolated from weeds with disease symptoms and submitted separately to submerged fermentation. Initially, the bioherbicidal activity was evaluated in Cucumis sativus plants, and the most promising were applied in Amaranthus hybridus and Echinochloa crusgalli. Treatments with fermented broth obtained from co-cultivation and ultrasound-assisted extraction after the fermentation process indicated an inhibition of plant development. The most promising strains were A14.2 and B22.2 (Nigrospora sphaerica), B14 (Bacillus velezensis), and γ (Aspergillus flavus).
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