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Повышение эффективности снятия покровной ткани с плодов томата импульсным электрическим полем
(2022)
Electrophysical technologies are a global trend of sustainable agriculture and food industry. Peeling is an energy-intensive procedure of fruit and vegetable processing. The research featured the effect of pulsed electric field (PEF) treatment on tomato peeling effectiveness. The assessment included such factors as specific effort, energy costs, and product losses in comparison with thermal and electrophysical methods. Tomatoes of Aurora variety underwent a PEF treatment at 1 kV/cm. The expended specific energy was 1, 5, and 10 kJ/kg. The tomatoes were visually evaluated with optical microscopy before and after processing. The peeling effectiveness and mass loss were measured with a texture analyzer and digital scales. The PEF treatment decreased the specific force of mechanical peel removal by 10% (P < 0.05). The mass loss decreased by 4% (P < 0.05) at 1 kJ/kg. The PEF method resulted in cell electroporation, which activated the internal mass transfer of moisture from the endocarp region between the mesocarp and the integumentary tissue. The hydrostatic pressure produced a layer of liquid, which facilitated the peeling. In comparison with thermal treatment (blanching), ohmic heating, and ultrasonic processing, the PEF technology had the lowest production losses and energy costs. The research proves the prospects of the PEF treatment in commercial tomato processing.
Plant-based proteins are rapidly emerging, while novel technologies are explored to offer more efficient extraction processes. The current study aimed to evaluate the effects of pulsed electric fields (PEFs) and temperature on the extraction of soluble proteins from nettle leaves (Urtica dioica L.) and identify an optimal operational range for the highest yield of soluble proteins. Extractions and kinetic modeling were conducted with whole and ground dried leaves at different temperatures (30–70 °C) and specific energy of PEF (0–30 kJ kg−1) with extraction times of up to 60 min. The influence of temperature and specific energy on the soluble protein extraction yields was investigated and modeled using composite central design and response surface methodology. The experimental results were fitted to Peleg's kinetic model, which satisfactorily described the extraction process (R2 > 0.902), and PEF treated samples resulted in a higher soluble protein yield and shortened processing time. Response surface methodology showed that the linear effect of temperature and quadratic effect of PEF (p < 0.01) were highly significant for protein yield. In the optimized PEF-extraction region (specific energy between 10 and 24 kJ kg−1, and 70–78 °C), soluble protein yield was higher than 60% after 5 minutes of extraction. The achieved results are relevant for developing processes for PEF assisted extraction of soluble proteins from leaves. Understanding the effects of PEFs and process parameters is crucial to obtain high protein yields, while requiring low energy and short processing time.
The kiwifruit processing industry is focused on product yield maximization and keeping energy costs and waste effluents to a minimum while maintaining high product quality. In our study, pulsed electric field (PEF) pretreatment enhanced kiwifruit processing to facilitate peelability and specific peeling process and enhanced valorization of kiwifruit waste. PEF optimization was applied to obtain the best treatment parameters. A 32 factorial design of response surface methodology was applied to find the effect of time elapsed after PEF treatment and the PEF-specific energy input on specific peeling force and kiwifruit firmness as response criteria. Under the optimized condition, the specific peeling force decreased by 100, and peelability increased by 2 times. The phenolic content and antioxidant capacity of PEF-treated kiwifruit bagasse were 5.1% and 260% richer than the control sample. Overall, the optimized PEF pretreatments incorporated into kiwifruit processing led to decreased energy demand and increased productivity.
Optimization of important drying parameters with PEF pretreatment was carried out using Hermetia illucens larvae tissue. Three level factorial design of response surface methodology was used for the study varying specific PEF energy input 10–20 kJ/kg and drying temperature of 50–90 °C. Important average H. illucens larvae temperature during the drying process was obtained by numerical simulation from Luikov drying model. Consumption of drying energy was affected more by the drying temperature, than by the PEF energy. This indicated that range between 81 and 84 °C drying temperature and range from 11.2 to 13.1 kJ/kg of specific PEF energy input may be considered as optimal processing window for larvae drying.
Insect production for food and feed purposes is rapidly emerging in Europe, in many cases relying on existing processing methods for blanching, freezing, drying, fractionating, but also seeking for more efficient and beneficial biomass treatment methods. Current study is aimed to explore the application of Pulsed electric fields (PEF) pretreatment of insect biomass (Hermetia illucens) for drying and oil extraction enhancement. The study demonstrates an increase in the drying rate of larvae pre-treated with PEF at 2 and 3 kV/cm; 5, 10 and 20 kJ/kg wet basis. No effect on fatty indices and amino acids profile were determined, but more free total amino acids especially at PEF with E = 2 kV/cm and 20 kJ/kg, were identified in press cake after pressing. Results from this study show, that PEF could be used as a pre-treatment before drying of insect mass to increase the drying rate or to decrease the drying time and the content of functional ingredients under gentle conditions. Slight increase in the oil yield after PEF treatment allows to propose this technique for oil extraction improvement.
Currently, the modelling of drying processes of plant tissues pre-treated by pulsed electric field (PEF) is following experimentally identified curves or separate heat and mass transfer and diffusion models with different levels of accuracy. This research had two major objectives: mathematical modeling and control of drying process of different vegetables pretreated by PEF during convective drying. The mathematical modeling was based on Luikov's heat and mass transfer model along with properties of different vegetables. Computer modelling was done using the difference method for predicting moisture and the temperature potentials of untreated and PEF-treated vegetables. The formulation and the solution procedures were applied to simulate the simultaneous heat and mass transfer in selected vegetables subjected to the convective drying. Suggested model had a good correlation with experimental results. Moreover, cell disintegration index can be used as a controllable parameter in heat and mass transfer models to predict drying behavior of potato, onion, and carrot tissues. Obtained drying models can be used as a mathematical tool to predict drying behavior for various types of agricultural products pre-treated by pulsed electric field.