scholarly journals Energy analysis of an ultrasound-assisted atmospheric freeze-drying process for food

2018 ◽  
Author(s):  
Juan A. Cárcel ◽  
Daniele Merone ◽  
Domenico Colucci ◽  
Davide Fissore ◽  
Neus Sanjuán
Keyword(s):  
Energy Consumption ◽  
Freeze Drying ◽  
Operating Conditions ◽  
Model Parameters ◽  
Dehydration Process ◽  
Drying Process ◽  
Water Diffusivity ◽  
Ultrasound Assisted ◽  
The Impact ◽  
Air Dryer

Power ultrasounds have been proposed and extensively investigated as an effective way to speed up the atmospheric freeze-drying process, thus making this dehydration process attractive from an industrial viewpoint. Nevertheless, a rigorous investigation on the impact of power ultrasounds on the energy consumed by the process is still missing. This paper aims to investigate this issue. Apple, carrot and eggplant were chosen as representative products with different textures and water content. A mathematical model of the whole plant required to carry out the atmospheric ultrasound-assisted drying process was developed to assess the effect of the operating conditions on the energy consumption. Model parameters were tuned on the basis of the results obtained in a pilot-scale unit, thus allowing the use of the model to simulate the whole industrial dehydration process. Life Cycle Assessment (LCA) was used as a complementary tool to gain an insight on the environmental impact of the process. Results showed that due to differences in the water diffusivity for the analyzed products, substantial differences in energy consumption can be highlighted. In fact, when the water diffusivity increases, the capacity of the material to move water away also increases and the time to obtain a dry product is thus reduced. Moreover, although the use of ultrasound causes an increase in the hourly energy consumption (kWh·h-1), the total energy consumption of the whole process (kWh) is lower, since the total operation time is reduced. The LCA results highlighted the cooling system as the most critical stage for all the impact categories studied. This is mainly due to the use of ethylene glycol and R-404 in the refrigeration cycle. Nevertheless, when dehydrating low porosity products the energy consumption of the air dryer increased and this stage becomes, the most critical from an environmental point of viewKeywords: atmospheric freeze-drying, ultrasounds, process modeling, LCA.

scholarly journals Modeling Bacterial Regrowth and Trihalomethane Formation in Water Distribution Systems

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 463
Author(s):  
Gopinathan R. Abhijith ◽  
Leonid Kadinski ◽  
Avi Ostfeld
Keyword(s):  
Distribution Systems ◽  
Water Distribution ◽  
Mechanistic Model ◽  
Water Distribution Systems ◽  
Sensitivity Study ◽  
Operating Conditions ◽  
Growth Rate Constant ◽  
Model Parameters ◽  
Bacterial Regrowth ◽  
The Impact

The formation of bacterial regrowth and disinfection by-products is ubiquitous in chlorinated water distribution systems (WDSs) operated with organic loads. A generic, easy-to-use mechanistic model describing the fundamental processes governing the interrelationship between chlorine, total organic carbon (TOC), and bacteria to analyze the spatiotemporal water quality variations in WDSs was developed using EPANET-MSX. The representation of multispecies reactions was simplified to minimize the interdependent model parameters. The physicochemical/biological processes that cannot be experimentally determined were neglected. The effects of source water characteristics and water residence time on controlling bacterial regrowth and Trihalomethane (THM) formation in two well-tested systems under chlorinated and non-chlorinated conditions were analyzed by applying the model. The results established that a 100% increase in the free chlorine concentration and a 50% reduction in the TOC at the source effectuated a 5.87 log scale decrement in the bacteriological activity at the expense of a 60% increase in THM formation. The sensitivity study showed the impact of the operating conditions and the network characteristics in determining parameter sensitivities to model outputs. The maximum specific growth rate constant for bulk phase bacteria was found to be the most sensitive parameter to the predicted bacterial regrowth.

scholarly journals Studies on the Catalytic Properties of Crude Freeze-Dried Preparations of Yarrowia lipolytica Extracellular Lipases for Geranyl Ester Derivative Synthesis

Biomolecules ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 839
Author(s):  
Karina Jasińska ◽  
Bartłomiej Zieniuk ◽  
Dorota Nowak ◽  
Agata Fabiszewska
Keyword(s):  
Freeze Drying ◽  
Antioxidant Properties ◽  
Antibacterial Properties ◽  
Synthetic Activity ◽  
Drying Process ◽  
Enzyme Preparations ◽  
Ester Derivative ◽  
Freeze Dried ◽  
The Impact ◽  
Geranyl Ester

The study aimed to evaluate the impact of selected factors of the freeze-drying process on the hydrolytic and synthetic activity of the extracellular lipases of Y. lipolytica KKP 379 and to attempt the use of the crude enzyme preparation as a biocatalyst in the synthesis of geranyl 4-hydroxyphenylpropanoate. Antioxidant and antibacterial properties of the geranyl ester derivative were also investigated in order to evaluate their usefulness as a novel food additive. The studies confirmed that freeze-drying was an effective method of dehydrating yeast supernatant and allowed for obtaining lyophilizates with low water activity from 0.055 to 0.160. The type and concentration of the additive (2–6% whey protein hydrolyzate, 0.5% and 1% ammonium sulphate) had a significant effect on the hydrolytic activity of enzyme preparations, while the selected variants of drying temperature during the freeze-drying process were not significant (10 °C and 50 °C). Low yield of geranyl 4-hydroxyphenylopropionate was shown when the lyophilized supernatant was used (5.3%), but the yield of ester synthesis increased when the freeze-dried Y. lipolytica yeast biomass was applied (47.9%). The study confirmed the antioxidant properties of the synthesized ester by the DPPH• and CUPRAC methods, as well as higher antibacterial activity against tested bacteria than its precursor with 0.125 mM MIC (minimal inhibitory concentration) against L. monocytogenes.

The Impact of Electric Hybrid Compressor to Make Transport Environmentally Friendly

2013 ◽  
Vol 391 ◽  
pp. 207-212
Author(s):  
Maciej Bajerlein
Keyword(s):  
Energy Consumption ◽  
Operating Conditions ◽  
Vehicle Speed ◽  
Suspension Systems ◽  
Actual Operating ◽  
Vehicle Operation ◽  
Total Energy Balance ◽  
The Impact ◽  
Road Emission ◽  
Speed Engine

This paper presents the investigations, whose aim was to determine the influence of the operation of electric and mechanical compressors on the energy consumption of city buses in public transport. The tests were performed on pneumatic systems used in city transit vehicles whose underlying component is a compressor generating pressure for the brake and suspension systems. Owing to the application of a portable analyzer - SEMTECH DS the emissions (with a secondly resolution) of CO, HC, NOx, CO2 in the exhaust gases were measured. The on-road emission tests were performed in the actual operating conditions in SORT driving tests. These tests reflect the actual vehicle operation in a real task through preset procedures of their realization and measurements determining the energy consumption and exhaust emissions or the influence of the vehicle accessories and all variables (vehicle speed, engine load, acceleration or distance covered) on the total energy balance. The on-road tests were performed on a runway of the Bednary airstrip in Poland.

scholarly journals Study and optimization of freeze-drying cycles of a model probiotic strain

2018 ◽  
Author(s):  
Pierre Verlhac ◽  
Séverine Vessot-Crastes ◽  
Ghania Degobert ◽  
Claudia Cogné ◽  
Julien Andrieu ◽  
...  
Keyword(s):  
Experimental Study ◽  
Survival Rate ◽  
Lactobacillus Casei ◽  
Freeze Drying ◽  
Survival Rates ◽  
Probiotic Strain ◽  
Porous Matrix ◽  
Drying Process ◽  
The Matrix ◽  
The Impact

This work is based on the experimental study of the freeze-drying process to understand the impact of numerous factors on the survival rates of a model probiotic strain of Lactobacillus casei type. With the aim to find out if cell density in the matrix and survival rates are linked, we have studied the location of the cells after freeze drying inside a porous  matrix composed of a lactose basis with a polymer, the polyvinylpyrrolidone (PVP) in various amounts. The best survival rate were obtained at slow freezing rate for a formulation containing 5% (m/V) of lactose and 5% (m/V) of PVP. Keywords: Freeze-Drying; Freezing; Probiotics; L. Casei ATCC 393 

scholarly journals A Practical Methodology for Forecasting the Impact of Changes in Influent Loads and Discharge Consents on Average Energy Consumption and Sludge Production by Activated Sludge Wastewater Treatment

2021 ◽  
Vol 13 (21) ◽  
pp. 12293
Author(s):  
Catarina Silva ◽  
Maria João Rosa
Keyword(s):  
Wastewater Treatment ◽  
Energy Consumption ◽  
Activated Sludge ◽  
Average Energy ◽  
Oxygen Demand ◽  
Operating Conditions ◽  
Limit Values ◽  
Oxygen Requirements ◽  
The Impact ◽  
Sludge Production

This paper proposes a simple and easy-to-use methodology for forecasting the impact of changes in influent chemical oxygen demand (COD) and in the emission limit values (ELVs) of COD and total nitrogen on average energy requirements for aeration and sludge production by activated sludge wastewater treatment plants (WWTPs). The methodology is based on mass balances of sludge production and oxygen requirements for carbonaceous material biodegradation and/or nitrification, oxygen transfer and aeration equipment efficiency. Using average values of historical data of regular monitoring (water quality and operating conditions) WWTP-specific equations of oxygen requirements, energy consumption and sludge production are derived as a function of influent COD and influent N-total, which may be used to quantify the impact of influent and ELV changes. The methodology was tested in five extended aeration WWTPs for three scenarios established by the utility. The results show that increasing influent COD, from 900 to 1300 mg/L, for example, significantly increases the energy consumption by 49% and sludge production by 53%. For influent 54–68 mg/L N-total, imposing 15 mgN/L ELV results in a 9–26% increase in energy consumption. The COD ELV change studied (season-specific, from 150 mg/L 12 months/year to 125 mg/L 8 months/year to 100 mg/L 4 months/year) increases the energy consumption by 1.8–2.6% and the sludge production by 4.3–5.4%.

Studies on Decreasing Energy Consumption for a Freeze-Drying Process of Apple Slices

2009 ◽  
Vol 27 (9) ◽  
pp. 938-946 ◽  
Author(s):  
Lue-lue Huang ◽  
Min Zhang ◽  
Arun S. Mujumdar ◽  
Dong-feng Sun ◽  
Guan-wei Tan ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Freeze Drying ◽  
Drying Process ◽  
Apple Slices

scholarly journals The Impact of Drying and Rehydration on the Structural Properties and Quality Attributes of Pre-Cooked Dried Beans

Foods ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1665
Author(s):  
Shruti Aravindakshan ◽  
Thi Hoai An Nguyen ◽  
Clare Kyomugasho ◽  
Carolien Buvé ◽  
Koen Dewettinck ◽  
...  
Keyword(s):  
Freeze Drying ◽  
Drying Process ◽  
Total Peak Area ◽  
Diffusion Controlled ◽  
Freeze Dried ◽  
Stable Product ◽  
Shelf Stable ◽  
The Impact ◽  
And Diffusion ◽  
Highly Porous

Fresh common beans can be made ‘instant’ to produce fast-cooking beans by first soaking and cooking the beans before drying to create a shelf-stable product that can be rehydrated at the time of use. This study investigated the interplay between the drying process (air, vacuum and freeze drying), the microstructure and functional attributes of rehydrated pre-cooked beans. The microscopic study revealed that the three different drying techniques resulted in distinctly different microstructures, with the freeze drying process resulting in highly porous materials, while the air- and vacuum-dried samples underwent shrinkage. Additionally, the rehydration behavior (modeled using empirical and diffusion models) demonstrates that the high rehydration rate of freeze-dried beans is due to capillarity, while rehydration, in the case of air- and vacuum-dried beans, is primarily diffusion-controlled. Irrespective of the drying technique, the high rehydration capacity supports little to no structural collapse or damage to the cell walls. The color and texture of the rehydrated beans did not differ greatly from those of freshly cooked beans. The total peak area of the volatiles of rehydrated beans was significantly reduced by the drying process, but volatiles characteristic of the cooked bean aroma were retained. This new understanding is beneficial in tailoring the functional properties of pre-cooked dry convenient beans requiring short preparation times.

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