The current study deals with an innovation in the hot air convective drying process consisting of the application of two consecutive drying steps. Temperatures ranging between 60 and 80 ℃ for times between 200 and 600 s were applied for the first stage, and from 40 to 80 ℃ for the second stage. Salvia officinalis, an aromatic, medicinal Mediterranean plant with remarkable antioxidant properties, was selected for this study. A management of the process regarding the antioxidant capacity of S. officinalis extracts and energy consumption was carried out: (i) artificial neural networks were applied to model the evolution of the antioxidant capacity and moisture content of the product in the drying process; (ii) a genetic algorithm and a multiobjective genetic algorithm were selected to optimize the drying process, considering the antioxidant capacity and/or the energy consumption in the objective function. The results showed that the optimum values depended, logically, on the controllable variables values (hot air temperatures and drying times), but also on the uncontrollable variable values (room air temperature and relative humidity and the product's initial mass and moisture content).
The aim of this study was to develop a minimally processed persimmon product by applying different concentrations of thyme essential oil or lemon essential oil on the product in order to increase its shelf life. Essential oils were applied on cut persimmon in a preliminary stage of immersion, and the samples were then stored at 4 ℃ for seven days. Moisture content, soluble solids content, antioxidant capacity, total phenols, pH, optical and mechanical properties and microbiology counts were periodically analysed. Noteworthy was that the application of thyme essential oil in the washing stage improved the preservation of the fruits' colour. All samples would be considered safe according to microbiology requirements and based on the period of study, regardless of the type of essential oil applied.
The aim of this study was to evaluate the effect of a modified atmosphere (5% and 10% 7 of CO2) and calcium lactate treatment on the respiratory metabolism of minimally 8 processed persimmon. A static system to measure changes in the composition of the 9 headspace was used. Composition, texture and colour were also analysed. Persimmon 10 slices were evaluated immediately after the washing treatment and after the O2 11 composition had decreased to 17% to avoid changes in the metabolic pathway. All
The optimal design of a convective drier is hereby considered by means of using a well-known spreadsheet: Microsoft Excel 5.0Tm.The degree of freedom analysis enabled a non linear equations system to be set up, in such a way that it was possible for different design variables to be considered. The equations system was keyed in to provide a possible solution via the iterative procedure built in the spreadsheet. Other complementary variables were computed to provide a unit cost for the operation, thus occasioning the opportunity of considering an economic objective function.Constraint and design variables were identified in the program. By giving initial values to the design variables, and by using the optimization capabilities included in Microsoft Excel 5.0TM, an optimal set of values for the design variables was determined.Finally, the influence of constraint and design variables was analyzed, where both the input air temperature and the relative humidity of exhaust air were binding factors.Copyrighl 0 1995 by Marcel Dskkcr, Ins.
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