Initial Product Temperature Research Articles

Evaluasi Kecukupan Panas dan Pengembangan Proses Alternatif dalam Sterilisasi Komersial Jamur Kancing dalam Kaleng

. This research aimed to evaluate the adequacy of heat treatment and redesign the commercial sterilization process for canned button mushrooms to ensure that the product meets the minimum sterilization requirement without undergoing excessive processes. The study conducted tests on heat distribution and penetration, calculated the sterilization value (F0) using the trapezium and Ball methods, and designed an alternative sterilization process to avoid excessive procedures. The sterilization process for canned mushrooms, with a can dimension of 300x407, involved a temperature of 132°C for 16 minutes, resulting in an F0 value of 161.7 minutes. This value far exceeds the required minimum F0 value. To optimize the process, an alternative sterilization procedure was developed. It involved a temperature of 126°C, a process time of 10 minutes, and an initial product temperature of 40–50°C. This alternative process yielded an F0 value of 10 minutes. Furthermore, additional alternative process conditions were designed, with considerations to various process times (Pt), initial temperatures (Ti), retort temperatures (TR), and F0 values.

Адаптация математической модели процесса кондуктивного замораживания к икре сазана как источнику лецитина и ее решение

In modern conditions the food industry of the Russian Federation needs high quality natural emulsifiers, for example, lecithins. It should be noted that the carp caviar, in particular, the sazan caviar contains a large amount of lecithin. Analysis of the positive and negative aspects of different approaches to the freezing process and its structural design leads to the conclusion that it is reasonable to use (both from the point of view of technology, power consuming and economy) a conductive energy removal from the product that is in contact with the working surface of the cooling unit made in the form of a drum with a refrigerant supplied inside it. Given that it is difficult to empirically determine the temperature over the volume of the frozen object, it is advisable to simulate the processes of internal transfer of thermal energy and its exchange at the interfaces between the sample and the external environment, as well as the cooling surface of the drum. The aim of the study was a mathematical model solution about internal heat transfer during sazan caviar freezing under heterogeneous boundary conditions. The object of the study is a thin layer of the sazan caviar. Putting into practice the mathematical model of heat transfer, which describes freezing a 5 mm thick caviar product by the contact method by means of the finite difference method was realized by using the Mathcad Professional software product. In the process of solving the mathematical model of freezing, it was revealed that at the end of the freezing procedure, the average volumetric temperature of the caviar reaches its rational value of –7.5°C, after which the caviar product can be transported to the storage places. Rational operating parameters 
 of the caviar product freezing process are: ambient air temperature up to 20°C; initial product temperature –10 ± 1°C; drum surface temperature up to –18°C; thickness of the frozen layer – 5 ± 0.5 mm; freezing time = 10 minutes.

Venting stage experimental study of food sterilization process in a vertical retort using temperature distribution tests and energy balances

Thermal sterilization of canned food is widely used in the food preservation industry. This method ensures the microbiological safety of the products, helps to define their sensory properties, and preserves their nutrients. However, sterilization requires a significant amount of energy, which has an impact on the cost of the final product and the environment. In this paper, we present an experimental study into the energy balance in a vertical steam retort in a transient state during the venting stage with an initial product temperature of 4 °C and a container size of 63.5 × 30.16 mm. We carried out the experiments in accordance with the protocol for conducting temperature distribution studies developed by the Institute for Thermal Processing Specialists (IFTPS). Additionally, by means of a heuristic optimization method, we determined an optimal venting program for the process and its energy efficiency. The total energy consumption was 32.5 MJ; the thermal efficiency of the process, 43.88%; the losses through walls, drainage, venting, and purging, 27.82%; the energy required to heat the retort and the fittings, 22.91%; and others losses, 7.0%. Furthermore, we studied the phenomena associated with the sterilization process to propose strategies to reduce energy consumption.

Modeling and simulation of Byssochlamys fulva growth on papaya pulp subjected to evaporative cooling

This study reports the effects of evaporative cooling on the shelf life of papaya pulp contaminated with Byssochlamys fulva spores. The effects of the initial product temperature, velocity and relative humidity of the refrigeration system air were taken into account in the process analysis. A mathematical model was constructed integrating equations that describe the phenomena of heat and mass transfer at the surface of a food sample with the kinetics of microbial growth comprising the modified Gompertz equation, the extended square root model and the hyperbolic model. The mathematical model was implemented on Matlab and resolved numerically using the finite differences method. Simulations showed that the fruit׳s shelf life is primarily affected by its initial temperature. It was concluded that evaporative cooling can offer significant results in terms of extending shelf life if the initial product temperature is high and there is a low velocity refrigeration air stream. Under these conditions, simulations indicated that the shelf life of papaya pulp was extended by up to 70%, compared to processing without employing the evaporative cooling effect.

Integrating a kinetic microbial model with a heat transfer model to predict Byssochlamys fulva growth in refrigerated papaya pulp

Integrating mathematical modeling of process engineering with kinetic microbial models is a promising option for improving the food safety. In this study the effects of refrigeration air stream velocity and initial product temperature on the time taken for stored papaya pulp to be spoiled by Byssochlamys fulva were evaluated. A predictive model to describe the influence of temperature on the growth of this mold was developed. This model was then integrated with equations describing heat transfer in an infinite slab with a convective boundary condition. Several different refrigeration process scenarios were simulated. The results showed that the modified Gompertz model combined with the extended square root model and hyperbolic model offered the best description of the fungus’s behavior in papaya pulp. The simulations showed that product’s shelf-life can be reduced up to 76% in storage conditions of high temperature and low air velocity.

Sensitivity analysis of continuous ohmic heating process for multiphase foods

The process sensitivity analysis of continuous Ohmic heating process for soup products containing large particulates was performed by use of a validated computer modeling package to determine the critical control factors and their acceptable control ranges under given control targets. The major processing variables investigated included electrical conductivities of carrier fluid and particles, particle thermal diffusivity, surface heat transfer coefficient, particle size, particle concentration, flow rate, and initial product temperature. The response variables as the indicators of effects from processing variable deviations were the process temperatures and accumulated lethality values for both carrier fluid and particles at the end of holding tube. The results demonstrated that under giving base processing conditions with a control target process temperature of 133 °C (the carrier fluid temperature at the entrance of the holding tube or the end of heating tube), increasing carrier fluid electrical conductivity from 1.42 to 2.13 S/m at a reference temperature of 70 °C, particle size from 16 to 24 mm, and flow rate from 1600 to 2400 L/h could result in lower particle center temperature at the end of holding tube, while increasing particle electrical conductivity from 0.96 to 1.44 S/m at a reference temperature of 70 °C, thermal diffusivity from 1.16 × 10 −7 to 1.74 × 10 −7 m 2/s, surface heat transfer coefficient from 112 to 168 W/°C/m 2, particle concentration from 52% to78%, and initial product temperature from 56 to 84 °C could generate higher particle center temperature. Within the variable deviation ranges investigated, the importance order of effects of major processing variables were determined with respect to the particle center temperatures, carrier fluid temperatures and accumulated lethality values. The acceptable deviation ranges were built up for six major processing variables under meeting the required target Fo (at the particle center) values. The information and knowledge obtained from this study can be useful for understanding how major processing variables of continuous Ohmic heating processing system affect the required process target variables and the methodology developed in this study can be further used as a protocol for both process establishment and optimization purposes.

A Theoretical Study for Determination of Quality Equivalent Points for Volume Average Quality Evaluation in Conduction Heating Canned Foods

In the present study, a set of quality equivalent points, that is, points where the retention of a particular quality attribute at the end of a thermal process is equal to the volume average quality retention, was determined for conduction heating products in cylindrical containers. For this, initially, the temperature distribution inside the product during the thermal process was numerically calculated, assuming uniform initial product temperature, constant heating and cooling medium temperatures, and infinite heat transfer coefficient between the cylinder walls and the heating or cooling medium. Next, remaining concentration data at the end of the process were obtained at various points within the container for a heat labile quality factor following 1st-order degradation kinetics. Thereafter, the volume average remaining concentration for the quality parameter under consideration was calculated and the quality equivalent points were identified. The influence of product, quality factor, and process characteristics on the location of the quality equivalent points, was examined. For every case investigated, the entirety of quality equivalent points was modeled by the use of a single parameter, the empirical j value. For most cases of common practice, a j value between 0.34 and 0.40 was found appropriate for volume average quality retention calculations. Thus, by collecting temperature data during processing at a quality equivalent point, product quality at the end of the process can be assessed.

THERMAL PROCESS CALCULATION USING ARTIFICIAL NEURAL NETWORKS AND OTHER TRADITIONAL METHODS

ABSTRACT This work aimed to develop a method of thermal process calculation of canned food based on an artificial neural network and to compare it to the traditional Ball and Stumbo methods. A back‐propagation through time network was used as a model of heat conduction occurring in canned food, in order to predict the cold point temperature as a function of the autoclave and the initial product temperature. For training the network, a dataset of the cold point and retort temperature along time was obtained by processing a paste‐based product in autoclave. The network architecture (5‐8‐9‐1) was selected, presenting an excellent generalization capacity, with a mean relative error of 2.2% between the calculated F‐values of the observed and predicted time–temperature data. The Ball and Stumbo methods presented higher errors as the retort temperature was not constant. Neural network showed a great potential for online process calculation by having advantages such as precision and simplicity.

Effect of pulsed electric field processing parameters on Salmonella enteritidis inactivation

Pilot scale continuous pulsed electric field treatment of liquid products was tested on the effects of energy input (0 < Q < 300 kJ kg −1), electric field strength (25 < E < 70 kV cm −1), square wave pulse width (0.05, 0.1, 0.25, 0.5, 1, 2 and 3 μs) and initial product temperature (4 < T INIT < 20 °C) on Salmonella enteritidis inactivation in a model solution composed of 28 mM sodium sulfate and 28 mM glucose. For Q = 0–100 kJ kg −1, the decimal reduction number [DRN = log( N 0/ N)] can be considered as linearly related to Q with the decimal reduction energy [ Q D] varying between 44 ± 3.2 kJ kg −1 for 0.05 μs, 37 ± 2.5 kJ kg −1 for 0.1 μs and 32 ± 1.4 kJ kg −1 for 0.25–3 μs pulse width. For Q = 0–300 kJ kg −1, the relation between Q and log( N 0/ N) was of power law type with the threshold energy level Q 0 = 9 ± 2.6 kJ kg −1 and the power coefficient 3.17 ± 0.21. For Q = 65 kJ kg −1 the increase of T INIT by 6.6(±0.7) °C raises the DRN by one unit. The same effect increased the products’ electrical resistance by 16(±1.4) Ω. For an overall treatment time of 1 μs, the DRN is linearly related to E, with threshold ( E 0) and decimal reduction ( E D) electric field strength: E 0 = 19 ± 1.8 and E D = 29.7 ± 1.2 kV cm −1, respectively.

Prediction of cooling time in injection molding by means of a simplified semianalytical equation

AbstractA simplified semianalytical equation, used successfully in food freezing/chilling time prediction, is proposed as a potential simple alternative for cooling time prediction in injection molding of polymer parts, amorphous or semicrystalline. This equation is based on a convective boundary condition for the mold‐part interface and requires information on the thermal contact resistance (TCR) or thermal contact conductance (TCC) at this interface, as well as information on the initial and final product temperatures, the mold surface temperature, and the thermal properties of the part. Eighty‐five data points for four polymers, Polystyrene (PS), Polycarbonate (PC), Polypropylene (PP), and Polyethylene (PE) were generated with C‐MOLD™, a commercial injection molding design software, and the performance of the proposed equation was tested. The % mean error and its standard deviation (SD) in cooling time prediction were, respectively, −11.61 and 2.27 for PS, −6.04 and 2.13 for PC, −7.27 and 6.55 for PP, and −8.88 and 2.93 for PE. It was also shown that the accuracy of the proposed equation is not affected significantly by the exact knowledge of the TCC, provided that the latter is not smaller than 1000–2000 W m−2 K−1. Since in this comparison all necessary temperatures were obtained from C‐MOLD™, methods of using the proposed equation independently were tested. The use of the inlet melt temperature as the initial product temperature increased the % mean error by mostly 1.5% while its SD remained practically the same. By incorporating a literature based heat balance method in the proposed equation, it was possible to use it as a stand‐alone predictor of polymer cooling time. The % mean error and its SD calculated this way were, respectively, −9.44 and 0.97 for PS, −9.44 and 0.83 for PC, −14.22 and 5 for PP, and −20.12 and 1.38 for PE. The proposed equation, at least in a preliminary stage, can be used successfully to predict the cooling time of the selected semicrystalline or amorphous polymers with the accuracy being higher for amorphous polymers. © 2003 Wiley Periodicals, Inc. Adv Polym Techn 22: 188–208, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.10048

Prediction of freezing time for food products using a neural network

An artificial neural network (ANN) was developed to predict the freezing time of food products of any shape. The Pham model was used to generate freezing time data and to train ANN based on Wardnets. The product thickness ( a), width ( b), length ( c), convective heat transfer coefficient ( h c), thermal conductivity of frozen product ( k), product density ( ρ), specific heat of unfrozen product ( C pu), moisture content of the product ( m), initial product temperature ( Ti), and ambient temperature ( T ∞) were taken as input variables of the ANN to predict freezing time. The effects of the number of hidden layer nodes, learning rate, momentum on prediction accuracy were analyzed. The performance of the ANN was checked using experimental data. Predicted freezing time using the ANN was proved a simple, convenient and accurate method. Selection of hidden nodes, learning rate and momentum were important to ANN predictions.

Effect of initial product temperature and initial pH on foaming time during vacuum evaporation of liquid whole eggs

During earlier studies on vacuum concentration of liquid egg white, the phenomena of foaming during the initial stages of the process were reported. In these studies, it was also shown that no concentration took place during the foaming period that varied from test to test. To minimize the total process time, this present study was undertaken to investigate what variables contributed to foaming, how they could be controlled, and what effect they had on product quality and functional properties. This study investigated the relationships among initial product temperature, initial pH, and foaming of liquid whole eggs. Two temperatures (9 and 20 C) and three pH levels (6.5, 7.3, and 8.5) were studied using a vacuum evaporation system with a maximum vacuum of 5 kPa. Tests showed that higher initial pH levels had decreased foaming times. At the end of foaming experiments, the liquid whole egg was evaluated to determine the extent of functional property change during foaming. A decrease in foaming time resulted in a decrease in whip time. The cakes made from the processed liquid whole egg had larger volumes than those from the unprocessed control. Furthermore, the liquid whole egg, which foamed the longest, had higher (P < 0.05) cake volumes. Our current experiments also verified our earlier findings that no product concentration takes place during the foaming process.

Computer modelling for the control of particulate sterilization under dynamic flow conditions

A finite difference model was used for predicting the centre temperature of particulates during ultra-high temperature processing under continuous flow conditions. This model compared favourably with the analytical solutions. A sensitivity analysis was carried out on the input parameters to the numerical model, which indicated that particulate size and thermal diffusivity were the most critical parameters influencing process lethality and cook value. For example, a spherical particulate (thermal properties defined) of 20 mm diameter required a holding time greater than 5 min at 135°C to achieve a minimum safe cook ( F 0 of 3.0 min for Clostridium botulinum), compared to a 10 mm spherical particulate which would have received an F 0 value of 68 min after 5 min processing at 135°C. The centre temperatures predicted using the model were sensitive to changes in the convective surface heat transfer coefficient in the range 100–300 W m −2 K −1, but became less sensitive as the values increased up to 500 W m −2 K −1. An initial product temperature change from 20 to 60°C resulted in an 8 min increase in process lethality for a 15 mm spherical particulate processed for 5 min at 135°C. The determination of experimental results in particulates of less than 20 mm (the critical dimension) was found to be significantly affected by conduction errors through the thermocouple wires, and therefore the model presented will be a useful prediction tool in situations of experimental uncertainty.

A Computer Simulation of Thermal Sterilization of Canned Foods With Sub-Freezing Initial Temperatures

Certain types of canned foods are best handled as a frozen slurry and retorting such products from an initially frozen state would be advantageous from the standpoint of materials handling. However, there is currently little information on this process. Accordingly, a computer simulation using finite difference techniques was developed to determine the added process time required to achieve commercial sterilization. Total required processing time could not be approximated as being the sum of the thawing time and the sterilization time as calculated by conventional methods. Total concentration of heat labile nutrient was found to be unaffected by the process and was independent of initial product temperature, despite the longer exposure of the product to high retort temperatures.

Technical Notes: Forced-Air Spinach Precooler

A forced-air precooler to rapidly cool fresh spinach in large bins was designed, constructed, and tested. Airflow, spinach mass, and cooling time were measured and recorded for several test runs. The mean seven-eighths cooling time or the time to reduce the initial product temperature to seven-eighths of the desired holding temperature for 10 tests was 3.92 hours. A comparison of airflow rates and cooling time was made, but further research is required to verify the relationship.

Calculation of Thermal Process Lethality for Conduction‐Heated Canned Foods

ABSTRACTThe problem of deriving a formula to calculate sterilizing values from temperature curves was examined. For the high sterilizing value range (U/f&gt;1), a simple algebraic formula was found that enabled the temperature approach g and the sterilizing value U to be calculated from each other to within 3%. For low sterilizing values (U/f&gt;1) regression equations were presented to calculate g from U. A table was also given as an alternative to the equations. The method took into account variations in initial product temperature and cooling water temperature. Being expressed in terms of dimensionless quantities, it was more generally applicable than previous methods derived along similar lines.

PREDICTION OF TEMPERATURE IN FROZEN FOODS EXPOSED TO SOLAR RADIATION

Simultaneous convective and radiative boundary conditions were incorporated into a one-dimensional three time level implicit finite difference scheme in rectangular coordinates. The scheme was used to calculate temperature profiles and temperature histories in a packaged frozen food exposed to the sun. The solution was verified by thawing slabs of a standard test material (Karlsruhe test substance) and orange juice in different environments. Procedures were developed to measure the temperature distribution and to estimate the radiation properties of the package surface. The maximum thickness of the slabs was 38 mm. The agreement between experimental and predicted food surface and center temperature profiles was determined by corresponding R2 values ranging from 0.872 to 0.998. The computer program was also used to predict temperature profiles in a 100 × 92 × 92-cm pallet of frozen food exposed to different environmental conditions. Conditions were cimulated by varying initial product temperature, product thermal properties, air resistance between the product and the package, external heat transfer coefficient, ambient temperature, and radiation surface properties of the carton.

CALCULATION OF OPTIMUM STERILIZATION CONDITIONS FOR PACKED CONDUCTION‐TYPE FOODS

ABSTRACTThe basis of the method is the short‐cut calculation procedure developed by Thijssen et al. (1978) for sterilization conditions yielding optimum quality retention for conduction heating of packed foods at constant temperatures of the heating and cooling medium. This method is improved and extended to variable temperatures of the heating and cooling medium as occur in continuous sterilizers. This is done by converting the variable temperature into a block temperature‐time relationship. By means of computer simulations of the sterilization process, the variable heating temperature is converted into a constant heating temperature and an increased homogeneous initial product temperature yielding the same lethal effect. The variable cooling temperature is converted into a constant cooling temperature and an additional heating time at constant retort temperature yielding the same lethal effect as is obtained during the actual cooling process. On the block temperature‐time diagram thus obtained the short‐cut calculation method is again applicable. The error introduced by this method in the calculated logarithm of the reduction of microorganisms is less than 20%.

Prediction of Aircooling Characteristics of Moist Food Products

ABSTRACT AN analysis of the aircooling characteristics of food products is presented. The coupled effects of heat and moisture transfer at the product surface are taken into account. The one-dimensional heat conduction equation in rectangular, spherical and cylindrical coor-dinates is solved using finite difference technique. The variation of product temperature with time is obtained in dimensionless form in terms of Biot number, wet bulb temperature of cooling air and initial product temper-ature. Typical results are presented in the form of charts. To facilitate quick estimation of cooling characteristics, correlations are obtained for the time variation of temperature as a function of the governing parameters. The theoretical predictions yield good agreement with experimentally determined time-temperature histories.

SHORT‐CUT METHOD FOR THE CALCULATION OF STERILIZATION CONDITIONS YIELDING OPTIMUM QUALITY RETENTION FOR CONDUCTION‐TYPE HEATING OF PACKAGED FOODS

ABSTRACTBased on analytical equations for the temperature distribution history in a container, the relation between the reductions of the concentrations of heat labile food components, including microorganisms. nutrients and sensory factors, and the kinetic parameters of the reactions causing these reductions, has been calculated numerically. For a constant temperature of the heating medium with time it is concluded that the loss of quality is almost minimal at one Fourier value of the heating time. This optimal Fourier value is a function of only the Biot number and the relationship between initial product temperature, cooling water temperature and retort temperature. At an infinite value of Biot and a cooling water temperature equal to the initial product temperature the optimum Fourier value amounts to 0.5. On the basis of this conclusion a short‐cut calculation method is developed. The method is valid for Biot numbers larger than 10, initial homogeneous product temperatures equal to or larger than the temperature of the cooling medium and for the main container geometries including spheres, cylinders and rectangular bodies. The method does not require tedious interpolations of tables. The calculation of the optimum process conditions to obtain the desired sterility and the calculation of the retention of the quality factor of interest require only a few minutes on a pocket calculator. For routine calculations the procedure can conveniently be programmed.