Pasteurization Unit Research Articles

Privacy Preserving Approximated Optimal Control of Pasteurization Unit Using Homomorphic Encryption

Homomorphic encryption (HE) enables computations to be carried out over encrypted data, ensuring data privacy during processing. This feature is lucrative in various fields, including general process control and network control systems. However, there are some limitations to the applicability of modern noisy HE schemes, especially for computationally more challenging control techniques, such as Model Predictive Control. One of the solutions to this problem is to use homomorphically encrypted neural networks trained to mimic the behavior of MPC. This paper showcases such a neural network and demonstrates its capabilities for data privacy preserving control of the laboratory pasteurization unit.

Socio-economic and environmental analysis on solar thermal energy-based polygeneration system for rural livelihoods applications on an Island through interventions in the energy-water-food nexus

Rural electrification is constrained by grid extension infrastructural cost, isolated low rural populations, lack of anchor loads, and repayment potential of villagers while decentralized renewable energy power is constrained by high capital cost, low reliability, and non-workable business models. Solar thermal energy can produce electricity, heating, cooling, water, and fuel and has the potential for storage for livelihood applications. Hence solar thermal energy-based cogeneration and polygeneration systems have the potential for intervention in rural livelihoods with a focus on the energy-land–water-food nexus. However, standalone solar thermal systems are capital intensive and shadowed by photovoltaics. In the current work, an island in the Indian Ocean is considered for the study, and a solar thermal energy-based hybrid polygeneration system is designed with end products such as electricity, heating, cooling for food storage, and desalinating to get pure water. The turbine, VAM, pasteurization unit, and membrane distillation unit are the considered components in the present analysis. The thermodynamic properties of the key components of the polygeneration system are identified and the energy and entropy balance of the system is done. The levelised cost of production of polygeneration outputs for 25-year operational life with an accelerated depreciation of 30% of the capital cost, over 8 years is carried out. It is found that the electricity and water pricing are INR 14.71 and INR 14.01 per unit which are not attractive. Normalization is done by adjusting the price of other polygeneration outputs namely refrigeration, hot water, and pasteurizing to make the electricity and water pricing feasible to achieve an IRR of 12.99% and payback of 9 years at a 5% annual escalation. The social cost saved with the benefit of polygeneration outputs is cumulated considering value addition in the supply chain to save agricultural produce and milk, which otherwise would have spoiled. The annual carbon emissions that are curtailed with solar thermal polygeneration outputs are cumulated and found to be 434 tonnes of carbon. The social cost and environmental cost due to carbon are considered as an incentive in the cost economic economics of polygeneration system and it is found that the IRR and payback can be improved to 17.98% and 6.2 years respectively. The work recommends policy interventions to promote decentralized solar thermal polygeneration systems for impact on rural livelihoods with a focus on the energy-water-food nexus.

Dynamic simulator and model predictive control of a milk pasteurizer

In this study, the design, optimization and dynamic modelling of a milk pasteurization unit have been developed, using the pseudo-component approach for describing milk properties. The fluid has been regarded as a mixture of five major categories, namely water, fats, proteins, carbohydrates, and minerals. Exploiting the optimal pasteurizer configuration, selected based on the total annualized cost, a dynamic model of the process has been also derived. The simulation of the system is then used as a virtual plant to develop a nonlinear model predictive control (NMPC) designed for rejecting the more important disturbances that can enter the system. The predicted trajectories have been calculated with a simplified version of the dynamic model, obtained by neglecting parameters temperature dependence. The NMPC performance has been compared with a PI controller in terms of set-point tracking and disturbance rejection. Similar results have been obtained when using the different control algorithms for the output responses, but the NMPC showed better behaviour of the manipulated variables.

Thermal post-treatment of digestate in order to increase biogas production with simultaneous pasteurization

Biogas production by anaerobic digestion (AD) of organic wastes is important for the transition to fossil free fuels in both the transport sector, industries and shipping. The aim of this study was to target the residual organic matter in the outgoing residue from the AD process, so called digestate, with different thermal treatment methods in order to improve digestate degradability and biogas potential upon post-digestion. The thermal treatment was performed at 55 °C in 24 h, 70 °C in 1 h and by thermal hydrolysis process (THP; 165 °C, 8 bar in 0.33 h), and were carefully selected to offer a simultaneous possibility for pasteurization of the digestate according to the regulations in Sweden. Digestates from ten full-scale biogas plants were collected, with different substrate profiles including wastewater treatment plant (WWTP), food waste digestion, agriculture digestion and manure digestion. The results showed that all thermal treatment methods caused increased dissolved organic carbon concentration (DOC). Four of the thermal treated digestates with the highest increase in DOC were subsequently tested for the bio-methane potential. Thermal treatments at 70 °C and THP, respectively, resulted in the highest increase in bio-methane potentials, with an increase of 15–39% for one WWTP, 38 – 40% for digestate from an agriculture digestion plant and 20 – 22% for digestate from a co-digestion plant treating food waste. Interestingly, the bio-methane potential from digestate treated with the energy-intense THP method, did not show any significant difference compared to thermal treatment at 70 °C for 1 h. The outcomes of this study suggest that placing a pasteurization unit between a main digester and a post digester, when applying two-step digestion allows for a combined pasteurization and increased biogas production.

Dynamic interspecies interactions and robustness in a four-species model biofilm.

Interspecific interactions within biofilms determine relative species abundance, growth dynamics, community resilience, and success or failure of invasion by an extraneous organism. However, deciphering interspecific interactions and assessing their contribution to biofilm properties and function remain a challenge. Here, we describe the constitution of a model biofilm composed of four bacterial species belonging to four different genera (Rhodocyclus sp., Pseudomonas fluorescens, Kocuria varians, and Bacillus cereus), derived from a biofilm isolated from an industrial milk pasteurization unit. We demonstrate that the growth dynamics and equilibrium composition of this biofilm are highly reproducible. Based on its equilibrium composition, we show that the establishment of this four‐species biofilm is highly robust against initial, transient perturbations but less so towards continuous perturbations. By comparing biofilms formed from different numbers and combinations of the constituent species and by fitting a growth model to the experimental data, we reveal a network of dynamic, positive, and negative interactions that determine the final composition of the biofilm. Furthermore, we reveal that the molecular determinant of one negative interaction is the thiocillin I synthesized by the B. cereus strain, and demonstrate its importance for species distribution and its impact on robustness by mutational analysis of the biofilm ecosystem.

Computational study for microwave pasteurization of beer and hypothetical continuous flow system design

Beer pasteurization is carried out in conventional systems where low temperature and long time process (56 min process with 13 min pre-heating, 14 min heating, 6 min holding time and 23 min cooling time) is applied for bottled or canned products. Longer process times lead to losses in the sensory properties. Another approach is flash pasteurization where the beer is first pasteurized and then filled into bottles or cans. For flash pasteurization, microwave (MW) process with rapid heating feature might be an innovative alternative. Therefore, the objective of this study was to explore the MW processing for beer pasteurization. For this purpose, a computational mathematical model was developed to determine the temperature change of beer during MW process and experimentally validated in a 2450 MHz lab-scale system. Following the validation, process design studies for a continuous flow system were carried out. These studies demonstrated the MW application as a rapid process (e.g. 60 s of total MW heating time at 5000 W with a short holding time of 27 s) to achieve the required pasteurization unit at a flow rate of 50.4 kg/h. This confirmed the MW process as a possible industrial application. Using these results, continuous flow process optimization studies for industrial process considerations might be planned.

Modeling time-temperature history and sterilization value of mango puree under conventional and microwave assisted pasteurization

Abstract Continuous pasteurization of liquid foods has to provide the desired lethality level to guarantee food safety with minimum degradation of quality attributes (sensorial and nutritional characteristics) and high energy efficiency. To optimize quality and cost, a thermal process should be modeled considering flow, heat transfer and mass dispersion principles; however, flow through helical tubes and microwave heating require a complex 3D multiphysics approach. Herein a simplified 2D approach is presented to model a hybrid pasteurization unit with conventional and microwave heating under laminar flow to predict axial and radial distributions of temperature and residual activity of a microorganism or enzyme. A study case of 20 °Brix mango puree (power law fluid) processing is used to test the model based on an existing pilot plant unit. Results were useful to compare conventional and microwave heating regarding the process sterilization value and model can be used for process analysis, design and optimization.

Physical and chemical indicators of raw spent grain

The results of experimental studies of physical and chemical indicators and amino acid composition of raw brewer’s grains from Belorechensky (the Krasnodar Territory) and Maykop (the Republic of Adygea) br eweries have been presented. The purpose of the research is to compare the physicochemical parameters and amino acid composition of raw brewer’s grains obtained pneumatically at the Belorechensk brewery and hydraulically at the Maykop brewery. Analyzes carried out in an accredited laboratory and testing center have shown that fresh grains from both breweries are non-toxic. Both breweries use PILSNER MALT by «Kurskiy Malt» and produce beer using classic technology. The content of sugar and starch in absolutely dry matter is higher in brewer’s grains of the Maykop brewery, which indicates a deeper additional sugar starch used in the technology of the Belorechensk brewery. The presence of essential amino acids methionine, arginine, valine, threonine, etc. characterizes the nutritional value of the grain. The content of crude protein in the brewer grains of the Belorechensk brewery is higher compared to that in the Maykop brewery grains, 5,1% and 4,2%, respectively, and the content of nitrogen-free extractive substances is higher in the brewer grains of the Maykop brewery and makes up 9,3% and 8,8% in spent grains of the Belorechensk brewery. The data obtained are consistent with the data of other researchers. Due to the high moisture content in the Maykop brewer’s grains, its indicators have been determined after moisture draining through a sieve. Analysis of the technological stages of beer production has shown that a pasteurization unit was installed at the Belorechensk brewery before bottling beer, which helps to increase its shelf life and destroy the active action of microorganisms, but to reduce the saturation of the beer taste.

Design of Solar Water Pasteurization System with Slow Sand Filtration

Solar water pasteurization system with slow sand filtration works by integration of filtration unit and pasteurization unit. The system can be utilized in rural as well as the urban areas of the country to produce reliable drinking water source. The filtration unit has layers of gravels and sand, and the pasteurization unit works by use of solar collector utilizing solar energy. The final output water is drinkable by treatment of water pathogens through the integrated units. The use of two systems: Pasteurization unit and Filtration unit independently checks and corrects the flaw of the other to produce clean and pure drinking water. The output water from the integrated system is tested and found to have reduced TDS from 159 mg/l to 137 mg/l, E. coli count from 6 CFU/100ml to 0 CFU/100ml and Total coliform count from 52 CFU/100ml to 0 CFU/100ml. This hybrid system uses solar energy for water pasteurization so it can be utilized effectively for drinking water purposes.

Correction of residence time distribution measurements for short holding times in pasteurization processes

Abstract When in-line cells are used for obtaining residence time distribution (RTD) data from systems with short residence time, the signal distortion caused by the cell can compromise the results. A procedure to correct such distortion using convolution of signals in the time domain is proposed. First, the RTD of the cell is characterized, and then the E-curve of an RTD model is convoluted with the cell curve. The convoluted E-curve is fitted to the experimental data by adjusting the mean time and the model parameter. The procedure is demonstrated using a pilot scale pasteurization unit with two heaters, one cooler and six options of holding tube. Pulse experiments were performed, E-curves were obtained for each process step and five RTD models were tested. The convolution procedure was successful in removing the distortion caused by the detection cell, which was very significant for the holding tubes.

DEVELOPMENT AND PERFORMANCE EVALUATION OF MILK PASTEURIZATION UNIT

The main objective of the present investigation was to use the modern technological modifications for the milk pasteurization process. The original milk pasteurization unit was developed especially for the present work by adding a pneumatic regulating valve to improve its performance. The performance of the milk pasteurization unit before and after development was experimentally studied under four different heating temperatures (70, 74, 77 and 80oC), four different vapor pressures (200, 400, 600 and 800 kPa) and four different cooling temperatures (3, 4, 5 and 6oC). Evaluation of the milk pasteurization unit was carried out taking into consideration pasteurization unit productivity, heating rate, fuel consumption, energy requirements, bacteria count and final product quality. The experimental results revealed that pasteurization unit productivity (258 kg/hr.), heating rate (4.9oC/s) fuel consumption (144 l/hr.), energy requirements (1.74 kW.hr./kg ) and bacteria count (35), were in the optimum region under conditions of using the developed milk pasteurization unit at 74oC heating temperature, 400 kPa vapor pressure and 4oC cooling temperature.

Improvement of the continuous "pipe in pipe" pasteurization unit

The result of improving the pasteurizer is a 6-fold decrease in the specific metal consumption by the device, in comparison with the basic design (26 kg/m 2 versus 160 kg/m 2 ). The duration of heating and pasteurization of drinking milk at a temperature of 73...77 °C while aging over 15...20 s is 27.5 s, which is 1.8 times less. A reduction in the heat consumption for heating the apparatus is achieved, which is 1,372.8 kJ (CPiPPU – Continuous in pipe pasteurization unit), in comparison to the consumption by the basic pasteurizer, 8,448 kJ. The uniformity of flow heating was established when its speed changes from 0.03 to 0.40 m/s for various heat supply techniques; under the condition υ=0.4 m/s, a temperature drop is ensured: at internal heating ‒ 1.4 °C; in the basic design with external heating by a hot heat carrier ‒ 2.7 °C; and in the proposed CPiPPU with double-sided heating ‒ 0.5 °C. The comparison of heat supply techniques confirms the heat exchange efficiency of raw material processing by CPiPPU while ensuring a minimum temperature drop. The improved continuous pipe-in-pipe pasteurization unit based on the double-sided heating by a flexible film resistive electric heater of the radiating type (FFREHRT) is resource-efficient and can be used to heat food raw materials in the temperature range 15...110 °C

Effects of temperature and fluid velocity on beer pasteurization in open and closed loop heating systems: numerical modeling and simulation

Abstract A two-dimensional symmetric heat transfer model and a fluid rotation model were established to study beer pasteurization process through the COMSOL Multiphysics software. Two heating modes, including closed-loop heating (CLH) and open-loop heating (OLH), were considered. There was a significant natural convection phenomenon in both heating systems. However, the natural convection became weaker with a gradual increase in the heating temperature of the beer. The maximum fluid velocity (FV) in CLH and OLH modes was 69.34 and 43.74 mm/s, respectively. After heating at 333.13 K for 20 min, the minimum and maximum pasteurization unit (PU) values in CLH were 55 and 59, respectively, while the corresponding values for OLH were 30 and 55, respectively. The pasteurization effect under the CLH mode was better than the OLH one. The heat transfer was also affected by fluid flow (laminar and turbulence) patterns. The PU value was nonlinearly related to the FV. The optimal FV can be obtained at ∼50 mm/s.

Identification of high temperature short time milk pasteurization unit

AbstractThis research pertains to the development of a dynamic‐model and identification of parameters for high‐temperature‐short‐time (HTST) pasteurization process using plate‐heat‐exchangers for precise controller scheme for this process. Real‐time HTST process consists of three integrated sections, (a) plate‐heat‐exchanger engaged in regeneration, heating and cooling (b) holding tank, and (c) holding tube. The models for these sections are identified using Matlab. The dynamics of the HTST process using the first‐principle method consisting of two inputs one‐output model is derived. The parameters of the dynamic model are identified using the autoregressive‐exogenous linear identification technique, ARMAX, and subspace system identification to predict the outlet temperature of HTST process. Finally, a dynamic‐model, relating exit temperature to input enthalpy is obtained from the closed‐loop process input–output data, using a nonlinear least‐square‐estimation technique. The quality of prediction of linear‐model structures is checked using plant's data. The results obtained from the linear‐models are in good agreement with plant‐data.Practical applicationMilk should be free from toxins and pathogens and also it must retain all nutrients and vitamins with extended period of storage life. To achieve the above said criteria, milk is heated to a particular temperature for a brief time then cooling it down once more quickly. Moreover, to avoid superheating, the temperature needs to be controlled. As model‐based‐control perform satisfactorily, tuning of controllers can be done using model parameters of this milk‐heating process. These model parameters are obtained from on‐line identification of the predicted model using real time plant input–output data. This paper deals with identification of model parameters for the milk pasteurization process. The formulated model equations are also validated, which will help in optimizing the operating parameters and scale‐up design.

Thermodynamic, economic and environmental impact studies on various distillation units integrated with gasification-based multi-generation system: Comparative study and optimization

Abstract This research proposes four scenarios for a multi-generation system to produce power, pasteurized milk, biofuel and fresh water for the northern areas of Iran. In all scenarios, power, pasteurized milk and biofuel are produced by a similar arrangement of a supercritical CO2 (S–CO2) Brayton cycle, a biomass gasifier and a milk pasteurization unit while the portable water is produced by a brine recirculation multi-stage flash (BR-MSF) in scenario 1, by forward, backward and parallel feed schemes of multi-effect distillation (BF, FF and PF-MED) in scenarios 2, 3 and 4, respectively. A comparative study is conducted for the exergy, exergoeconomic and exergoenvironmental performances of all scenarios with various stages and effects using Engineering Equation Software (EES). The optimum performances of all scenarios are found by applying the fast and elitist non-dominated sorting genetic algorithm (NSGA-II) and using linear programming technique for multi-dimensional analysis of preference (LINMAP), technique for order of preference by similarity to ideal solution (TOPSIS) and Shannon entropy decision makers. According to the results, the maximum distillate water with capacity of 400.6 m3/day is obtained for scenario 1 through Shannon entropy method. Moreover, scenario 4 gives the maximum exergy efficiency with a value of 44.16% using LINMAP method and scenario 2 with the lowest total cost and environmental impact (EI) rates of 77.15 $/h and 33.35 mPts/s, respectively obtained from TOPSIS method is the best layout from the economic and EI aspects.

Process control of milk pasteurization using Geothermal brine under Geothermal brine temperature and flow rate disturbance

Geothermal brine can be used as a heating liquid for pasteurization unit either by directly use the brine to heat up the raw milk, or by heating secondary fresh water. The geothermal brine can be obtained directly from geothermal well or from geothermal power plant separator. Unlike conventional pasteurization, the flow rate and temperature of geothermal brine might fluctuate due to many factors such as rain, well decline, and well shut down. Inherently the geothermal reservoir tends to decline in pressure and temperature. If the geothermal brine is obtained from geothermal power plant, then the flow rate and temperature of geothermal brine itself is susceptible to many changes in plant’s operation. A control system is needed for such utilization of geothermal brine. Simulation has been carried out to study the effect of PID feedback controller under geothermal brine temperature and flow rate disturbance. The result shows that PID controller could be used to compensate such disturbance. The PID controller controls milk inlet flow rate to balance the effect of both disturbances.

Lethality and quality evaluation of in-packaged ready-to-eat cooked Jasmine rice subjected to industrial continuous microwave pasteurization

ABSTRACTThe use of the pasteurization unit as a measure of the lethal effect of heating processes and overall quality of ready-to-eat Jasmine rice was determined in order to compare the conventional and microwave technology. Cooked Jasmine rice was packed in a polypropylene plastic cup and sealed with a lidding film, then subjected to a continuous microwave system (eight 800 W; 2450 MHz) and conventional steamer. The pasteurization unit, log reduction, microorganism count, color, instrumental textural property, and sensory attributes were investigated over a 30-day storage at 8°C. The pasteurization process time was reduced from 420 s under the conventional process to 216 s under the microwave process for a 5-log reduction of L. monocytogenes. The microwave heating showed greater effectiveness for shelf life, extending the product from 7 days (conventional) to 30 days. Cooked rice after heating by microwave was whiter and showed lower hardness than the conventional heated sample. Throughout storage, sensory attributes of the pasteurized product heated by microwave were acceptable by panelists. The addition of 15% trehalose or 1% soybean oil into the rice before cooking decreased the hardness of the cooked rice during storage. This study successfully demonstrated that the continuous microwave pasteurization process, compared to the conventional process, required less process time for ready-to-eat cooked Jasmine rice and extended the shelf life while providing better product quality.

Use of pasteurization unit for estimation of microbial quality of Iranian non – alcoholic beer using different thermal treatments and various types of packaging

Foods can be stored under good hygienic conditions with the aid of temperature without any chemical conservation. Pasteurization is a time – dependent process and may be an effective method for elimination of microorganisms. The efficiency of pasteurization unit (PU) could be demonstrated by microbiological analyses. The aim of this paper was to find and apply a PU which satisfied, in terms of time and temperature, the necessities of a good and healthy non – alcoholic beer packaged in keg, can, and bottle. The results showed that optimum conditions for pasteurization of non – alcoholic beer in three types of packaging were as follow: For keg packaging: 85°C for 2s (PU= 124); for bottle packaging: 68°C for 55 min (Min. PU = 200); and for can packaging: 68°C for 35 min (Min. PU= 100).

Heat transfer analysis of pasteurization of bottled beer in a tunnel pasteurizer using computational fluid dynamics

Abstract Beer is one of the most widely consumed alcoholic beverages in the world. Pasteurization is an important unit operation in beer processing that inactivates the spoilage microorganisms present in beer thereby extending its shelf life. It is difficult to determine the temperature profile and slowest heating zone (i.e. minimum heating region) inside the bottle during industrial scale tunnel pasteurization. Computational fluid dynamics (CFD) modeling can be used as a tool to determine the temperature distribution pattern inside the bottled beer. This study is unique in terms of using the actual thermophysical properties of beer unlike in earlier published works. Further, CFD simulation prediction of the temperature profile in the bottled beer was validated with experimental measurements. The study was extended to investigate the effects of different zones' temperatures on inactivation of Saccharomyces cerevisiae , the most common beer spoilage organism. A tunnel pasteurizer with seven zones was selected to study the temperature profile inside the bottled beer and found to be in good agreement with the published temperature profiles in different zones. In addition, the effectiveness of pasteurization was investigated in terms of pasteurization unit (PU) and the resultant PU value (15 to 30 PU) was adequate for achieving the maximum sterility of beer. Industrial relevance In recent years, a rapid development in the application of CFD in food processing operations has been witnessed. The main need for CFD analysis of pasteurization is to determine the uniform and effective heat distribution inside the bottled beer and to examine the position of slowest heating zone (SHZ). Relatively few works have been published related to applications of CFD during beer pasteurization. However, all the studies were performed with water as a model fluid. So far no work has been published on the CFD simulation during the pasteurization process in bottled beer by using the thermophysical properties of beer. Hence, the present study was aimed at investigating the temperature distribution inside the beer bottle during the pasteurization process and in each zone of the industrial tunnel pasteurizer. This model can be used for the brewery industry to ensure that the required pasteurization temperature has been reached inside the beer bottle when conveyed through a tunnel pasteurizer. This is very essential to render a safe product with extended shelf life to the consumers.

Assessing the failure frequency of potential hazardous incidents using radial basis function networks (RBFN). A milk pasteurization unit as study case

A case study involving analyses of the reliability was made from a selected pasteurization plant. The study involved a probability of failure and mitigation of selected typical installation. Recently, new studies indicate that the RBFN is a good tool for prediction of parameters such that the aim of this paper is to apply a RBFN approach as predictive model focus on the context of reliability. The proposed method herein is based on clustering of input space vectors and computing weights of Euclidian distances and histogram equalization within each cluster will determine the centre and width of each receptive field. The results of this paper indicate that the accuracy of the prediction obtained can be around 99.7%. Also, the model indicates that there is 9.2% additional risk in extending the operation from fourth to fifth year for major components having survived 3 years.