The aim of this study was to investigate the effect of solid-state fermentation (SSF) by Aspergillus niger on phenolic contents and antioxidant activity in Sambucus nigra L. and Sambucus ebulus L. berry pomaces. The effect of fermentation time on the total fats and major lipid classes (neutral and polar) was also investigated. During the SSF, the extractable phenolics increased with 18.82% for S. ebulus L. and 11.11% for S. nigra L. The levels of antioxidant activity of methanolic extracts were also significantly enhanced. The HPLC-MS analysis indicated that the cyanidin 3-sambubioside-5-glucoside is the major phenolic compound in both fermented Sambucus fruit residues. In the early stages of fungal growth, the extracted oils (with TAGs as major lipid fraction) increased with 12% for S. nigra L. and 10.50% for S. ebulus L. The GC-MS analysis showed that the SSF resulted in a slight increase of the linoleic and oleic acids level.
BackgroundThe use of agricultural and food by-products is an economical solution to industrial biotechnology. The apricot press residues are abounding by-products from juice industry which can be used as substrates in solid state fermentation process (SSF), thus allowing a liberation and increase of content from various biomolecules with high added value.MethodsThe evolutions of phenolic levels (by colorimetric assays and high performance liquid chromatography, HPLC–MS) and antioxidant activities (by DPPH assay) during SSF of apricot pomaces with Aspergillus niger and Rhizopus oligosporus were investigated. The changes in fatty acid compositions of oils in apricot kernels during SSFs were also analyzed by gas chromatography (GC–MS).ResultsThe results showed that the levels of total phenolics increased by over 70% for SSF with R. oligosporus and by more than 30% for SSF with A. niger. A similar trend was observed in the amounts of total flavonoids (increases of 38, and 12% were recorded for SSF by R. oligosporus and A. niger, respectively). Free radical scavenging capacities of methanolic extracts were also significantly enhanced. The main phenolic compounds identified through HPLC–MS in fermented apricot press residues were chlorogenic acid, neochlorogenic acid, rutin, and quercetin 3-acetyl- glucoside. This work also demonstrated that the SSF with filamentous fungal strains not only helped in higher lipid recovery from apricot kernels, but also resulted in oils with better quality attributes (high linoleic acid content).ConclusionThe utilization of apricot by-products resulting from the juice industry as waste could provide an extra income and at the same time can help in solving solid waste management problemsGraphical abstractChanges in phenolic compositions, antioxidant activities and total lipid contents during solid state fermentation (SSF) of apricot pomaces from juice industry with Aspergillus niger and Rhizopus oligosporus
This paper presents two tuning algorithms for fractional-order internal model control (IMC) controllers for time delay processes. The two tuning algorithms are based on two specific closed-loop control configurations: the IMC control structure and the Smith predictor structure. In the latter, the equivalency between IMC and Smith predictor control structures is used to tune a fractional-order IMC controller as the primary controller of the Smith predictor structure. Fractional-order IMC controllers are designed in both cases in order to enhance the closed-loop performance and robustness of classical integer order IMC controllers. The tuning procedures are exemplified for both single-input-single-output as well as multivariable processes, described by first-order and second-order transfer functions with time delays. Different numerical examples are provided, including a general multivariable time delay process. Integer order IMC controllers are designed in each case, as well as fractional-order IMC controllers. The simulation results show that the proposed fractional-order IMC controller ensures an increased robustness to modelling uncertainties. Experimental results are also provided, for the design of a multivariable fractional-order IMC controller in a Smith predictor structure for a quadruple-tank system
In this paper a fractional order (FO) controller is proposed for solving the vibration suppression problem in civil structures. A laboratory scaled steel structure, with one floor, modeled as a single degree-of-freedom system is used as a case study. Two passive control solutions are proposed: a tuned mass damper (TMD) and a viscoelastic damper (VED), the latter being modeled using fractional derivatives. The simulation results show that the VED is able to further reduce the vibrations induced as forced oscillations or due to seismic excitation inputs, as compared to the passive TMD. The FO controller is then tuned using a new approach based on imposing a magnitude condition for the closed-loop system at the structural resonance frequency. The resulting FO active control strategy, together with the VED, ensures an increased seismic mitigation. Structural modeling errors are also considered, with the proposed active FO control strategy behaving robustly in terms of vibration suppression. The novelty of the paper resides in the tuning approach, as well as in the proposed active control strategy that is based upon combing VEDs, described using an FO model, and an FO controller.
Carbon isotopes are widely used in numerous industries, especially in medicine. The advantage of using 13C‐labeled products is only shadowed by the difficulty of increasing the natural concentration. One method available is a train of cryogenic distillation columns. This paper presents a preliminary analysis of three different control strategies for a unit comprising three 7‐m‐high isotope separation columns: a decentralized multivariable proportional‐integral controller and two decoupling control algorithms. For the first one, a single controller is designed for the entire distillation column train, whereas for the second decoupling approach, three separate controllers are designed for each of the three columns. Simulation results show that the last approach provides significantly improved results when compared to the other two control strategies.
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