Modeling drying kinetics of paneer using Artificial Neural Networks (ANN)
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JOURNAL OF FOOD RESEARCH AND TECHNOLOGY Journal homepage: www.jakraya.com/journa/jfrt ORIGINAL ARTICLE Modeling drying kinetics of paneer using Artificial Neural Networks (ANN) Shivmurti Srivastav* and BK Kumbhar1 *Associate Professor, Department of Food Processing Technology, A D Patel Institute of Technology, New V V nagar, Anand, Gujarat-388121, India. 1 G B Pant University of Agriculture and Technology, Pantnagar, Uttarakhand-263145, India. Abstract Empirical model of low pressure superheated steam of Paneer were developed. Effect of steam pressure and temperature on drying time was *Corresponding author: evaluated. Page model showed higher R2 (0.997) and lower SD (0.0043) compared to generalized exponential and logarithmic models. The average Shivmurti Srivastav (PhD) value of parameter k and n for 1cm-cube paneer varied from 0.0041 to 0.0067 and 1.1552 to 1.2209, respectively while that for 1.5 cm-cube were Email: shivmurtis@gmail.com from 0.0021 to 0.0044 and 1.1987 to 1.3032, respectively. Moisture content, drying rate and moisture ratio data were generated by conducting the experiments in low pressure superheated steam dryer. Optimized ANN Received: 20/01/2014 models were developed for rapid and more accurate prediction of moisture content with one hidden layers and nine nurons having R2 0.9993, drying Revised: 02/03/2014 rate with one hidden layers and five neurons having R2 0.9977 and moisture ratio with two hidden layers and seven neurons having R2 0.9997 in drying. Accepted: 02/03/2014 ANN modeling can be used for predicting moisture content, drying rate and moisture ratio. Keywords: Artficial Neural Networks, Superheated steam, Drying, Paneer. Introduction (ANN) to food processing have opened up novel Food industry is always looking for a drying possibilities for processing industries (Susan, 1998). method which is rapid, energy efficient and yielding ANN has the capabilities of learning from the inputs uniform, hygienic and safe products (Nema et al., and outputs and developing relationship between them 2013). Superheated steam drying is a potential method that can be used for further prediction of outputs for the due to its several advantages. Product maintained given inputs. For nonlinear problems, ANN is a most higher porosity and better rehydration. Absence of promising alternative technique (Banggard and oxidative reactions (enzymatic browning, lipid Thodberg, 1992). The advantage of ANN over rule- oxidation), high heat transfer coefficients, higher based model is that, if the process under analysis drying rates, energy saving due to latent heat supplied changes, new examples can be added and ANN model to the dryer can be recovered. This drying method is can be trained. This is much easier than determining environment friendly since it is a closed system, no new models or rules. explosion or fire hazard, combination of drying with During last few years, interest in using Artificial other product treatment like pasteurization or Neural Networks (ANNs) as a modeling tool in food sterilization of food stuffs (Devahastin et al, 2004; technology is increased. ANNs have been successfully Deventer and Heijmans, 2001). The superheated steam used in several food applications like model for acts both as heat source and as drying medium to take prediction of physical properties of dried carrot, away the evaporated water. In process control, the main prediction of dryer performance, extrusion processing objectives are food safety, high quality and yield at of wheat and wheat-black soybean, energy minimal costs. To obtain high quality products, on-line requirements for size reduction of wheat, grain drying control techniques are required. Most food processes process, dough rheological properties among others are highly nonlinear, with time varying dynamics, (Islam et al., 2003, Kerdpiboon et al., 2006; Huang et which complicates food automation. However, the al., 1993; Shihani et al., 2004; Fang et al., 2000; Farkas recent developments in artificial intelligence based et al., 2000; Ruan et al., 1995). Artificial neural advanced control tools such as artificial neural network networks are mathematical models which have the capability of relating the input and output parameters, Journal of Food Research and Technology | January-March, 2014 | Vol 2 | Issue 1 | Pages 39-45 ©2014 Jakraya Publications (P) Ltd
Srivastav and Kumbhar………..Modeling drying kinetics of Paneer using Artificial Neural Networks (ANN) learning from examples through iteration, without pipeline to increase the steam temperature to desired requiring a prior knowledge of the relationships level of superheating. Temperature was controlled by between the process parameters. Several neural dimmerstat. network structures have been described, but the most The sample holder was made using thin commonly used is the multilayer perception. This stainless steel sheet into a circular disc with 15 cm network comprises an input and an output layer of diameter. It was connected to a balance by a thin rod processing units interconnected via one or more hidden passing through a G.I. pipe. One side of the rod was layers. attached to the sample holder and other side was rested Keeping the advantages of ANN, the present on analytical digital balance (Model XB-320M, Adair study was undertaken, to develop Artificial Neural Dutt and Co. (I) Pvt. Ltd., Kolkata). The balance was Network (ANN) models for drying kinetics of paneer placed in a smaller chamber. The balance had a using superheated steam drying methods. weighing capacity of 320g with a least count of 0.001g. Size of balance was 210 × 340 × 89 mm. The operating Materials and Methods temperature of the balance was 10°-50°C. The data Paneer was kept at 4°C in a refrigerator until recorded by the balance was transferred through the use. The initial moisture content of paneer was about serial cable by software to a computer (Remote Control 50% (wb). It was diced in to a cube of two different Version 1.0.38. Adair Dutt and Co. (I) Pvt. Ltd., sizes of 1×1×1cm3 and 1.5×1.5×1.5 cm3 with stainless Kolkata). Chromel - Alumel (K type) thermocouples steel knife. Paneer was pretreated with solution were installed to measure temperature of superheated containing 2.5% sodium chloride and 0.5% potassium steam at inlet of drying chamber, drying chamber, sorbate at 50°C for 10 min. About 50g paneer cubes product and balance chamber continuously. These were dipped into 500 mL solution. After pretreatment thermocouples were connected to the data logger cubes were then removed, and drained using stainless (Model 1551C12, Digitech, Roorkee, India). The steel mesh. The pretreatment was given to prevent fat temperature range of data logger was 0-900°C and loss from the paneer and browning. Before drying accuracy better than ±0.5%. Scan rate was 1-99 samples were blotted to remove the surface moisture s/channel. Thermocouple signals multiplexed and and put in the drying chamber. Drying experiments transferred to the computer through Terminal Software, were conducted at 62°, 72° and 82°C temperatures and installed in PC. A vacuum pump (Make Kirloskar 10, 14 and 18 kPa absolute pressures with superheated Pneumatic Co. Ltd, Pune, India) was used to maintain steam. the desired vacuum in the drying chamber. Experimental setup Drying experiments Experimental setup of low pressure superheated Prior to conducting the experiments, the steam steam dryer with its accessories is shown schematically was generated in the autoclave and maintained at in Fig 1. Main components of the experimental setup 103kPa. The drying chamber was heated using side were steam generator, drying chamber, vacuum pump wall electric heaters to maintain drying chamber and data acquisition system with computer. The drying temperature at 50°Cand to prevent condensation of chamber consisted of a box insulated properly with steam in the drying chamber. Once the desired drying rock wool. Inner dimensions of insulated chamber were chamber temperature obtained, approximately 50g of 40 × 45 × 45 cm. Two electric heaters of 1.5 kW pretreated sample was placed in the drying chamber. capacities each were provided on opposite side walls of Vacuum pump was switched on to maintain to desired the drying chamber. The temperature of drying operating pressure. After it steam inlet valve was chamber was controlled by a temperature controller opened slowly to flash the steam into the drying knob provided in front of drying chamber. Thermostat chamber. The steam temperature with respect to the was provided to maintain the temperature inside the desired pressure was controlled by a heating tape drying chamber. The drying chamber was connected by placed on the steam pipe. Ratio of the steam pressure in a pipe from bottom to a chamber in which digital the steam reservoir to that in the drying chamber was balance was kept. An autoclave was used as a steam rather high, the effect of adiabatic expansion of steam generator and a steam reservoir. The pressure of steam introduced in to the drying chamber on the steam was maintained using auto cut controls. A steam trap temperature was rather small. Therefore, required was provided to reduce accumulation of steam steam temperature was achieved by controlling the condensate in the reservoir. Steam was transported to electric heater placed in the drying chamber. Sample the drying chamber through a pipe insulated with glass weight was recorded continuously in the computer at wool. A heating tape, rated 1kw was mounted on steam 1min interval. Also, the temperature of drying chamber, product, steam and balance chamber were Journal of Food Research and Technology | January-March, 2014 | Vol 2 | Issue 1 | Pages 39-45 ©2014 Jakraya Publications (P) Ltd 40
Srivastav and Kumbhar………..Modeling drying kinetics of Paneer using Artificial Neural Networks (ANN) recorded by data logger at 1min interval. The samples to produce the corresponding output that may be passed were dried until the desired final moisture content of on to other neurons. about 1% db was obtained. Experiments were performed at 10, 14 and 18 kPa absolute pressure and Training and testing algorithms 62, 72 and 82°C steam temperature. All experiments MATLB software was used for Artificial Neural were replicated thrice. Same procedure was followed to Networks (ANN) modeling. The networks were dry all sizes of paneer cubes. simulated based on a multilayer feed forward neural network. This type of network is very powerful in Empirical modeling function optimization modeling (Kerdpiboon, 2006). Moisture ratio data were fitted to Page, The input layer, hidden layers, and output layer Generalized exponential and Logarithmic model in structures are shown in Fig 2. The inputs parameters order to select the best predictive model for low selected for modeling other than drying time and pressure superheated steam drying of paneer cubes. weights are given in Table 1: The models are given below: Table 1: Input parameters for modeling Page model: M − Mo Method of Back propagation MR = Mo − Me =Exp −kθ n ( ) (1) computation Algorithm Levenberg -Marquardt for minimization of where error θ = Drying time k, n = Model constants The network training Different size of epochs Goal Minimum error Generalized exponential model: M − Mo Transfer functions Hyperbolic tangent, MR = = A Exp ( − kθ ) (2) Linear sigmoid transfer Mo − Me function transfer function Where A, k = Drying constant The inputs included the time of drying and weight changing with time. The output layer consisted of %db, Logarithmic model: rate of drying (dm/dθ) and MR. The number of hidden M − Mo layers were two and number of neurons in each hidden MR = =a + b ln(θ) (3) layer varied from 1 to 9 (3, 5, 7, or 9). The networks Mo − Me were simulated with the learning rate equal to 0.05. For Where training and testing of ANN configuration different ratio of data sets were examined. It was found that 50% a,b =Dryingconstants of data set used for training and 50% for testing predicted the best output. ANN description of the drying process The neural network model consisted of an input, Selection of optimal ANN configuration a hidden and an output layer. The input layer has two The optimal configurations from training and nodes, which corresponded to two processing testing for each neuron were selected based on neural conditions or independent variables: time of drying and network predictive performance, which gave the corresponding weight of the sample. The output layer minimum error from training process. The mean consisted of three neurons or dependent variables, relative error (MAE), Standard deviation of MAE representing the moisture content (% db), drying rate (STDA), Percentage of relative mean square error (% and moisture ratio (Shrivastav and Kumbhar, 2009). MRE), and standard deviation of % MRE (STDR) were The nodes and the neurons were connected to each used to compare the performances of various ANN other by weighted links, wij , over which signals can moels (Kerdpiboon, 2006; Torrecilla, 2007). pass. The arriving signals multiplied by the connection weights are first summed (activation function) and then passed through the sigmoid function (transfer function) Results and Discussion Page, generalized exponential equation and logarithmic that enable prediction of drying curves of Journal of Food Research and Technology | January-March, 2014 | Vol 2 | Issue 1 | Pages 39-45 ©2014 Jakraya Publications (P) Ltd 41
Srivastav and Kumbhar………..Modeling drying kinetics of Paneer using Artificial Neural Networks (ANN) For simulation it is generally not convenient to Input layer Hidden layers Output (i) (j) (k) use individual value of page’s equation parameters k and n at selected experimental conditions. Therefore, it Bi Bi was decided to develop a model relating the page Time %db equation parameters to temperature and pressure. A dm/dt non linear regression analysis with second degree polynomial equation was used to determine Weight MR dependence of k and n on temperature and pressure. The polynomial relation for k and n is given in equation 4. Detailed coefficients for drying constants k and n are given in Table 4 at different operating Fig 2: Theoretical architecture of multilayer neural conditions. These models were developed in MATLAB network for prediction of moisture content, software. drying rate and moisture ratio paneer cubes undergoing low pressure superheated k 'or n' = AT 1 2 + B1T + C1 (4) 2 steam drying were evaluated. The results of regression A1 = a1 + a2 P + a3 P analysis are given in Table 2. It was found that Page model had higher R2 and lower standard deviation B1 = b1 + b2 P + b3 P 2 compared to other two models all experiments. C1 = c1 + c2 P + c3 P 2 Therefore, Page model was selected for further data A, B, C , a1 , a2 , a3 , b1 , b2 , b3 , c1 , c2 , c3 areconstants analysis. The values of k and n were obtained at different where P is pressure, kPa and T is temperature, 0C drying conditions of temperature and pressure for 1.0 and 1.5 cm cube. The average values of k and n at each The ANN modeling thus obtained for moisture condition are reported in Table 3. The average value of content, moisture ratio and drying rate summarized that parameter k and n for 1cm cube paneer varied from the individual drying data set of temperatures i.e. 62, 0.0041 to 0.0067 and 1.1552 to 1.2209, respectively 72 and 820C for each pressure and size (Eighteen ANN while that for 1.5 cm cube were from 0.0021 to 0.0044 models), combining drying data at all temperatures for and 1.1987 to 1.3032, respectively. each pressure (Six ANN models), combining drying Journal of Food Research and Technology | January-March, 2014 | Vol 2 | Issue 1 | Pages 39-45 ©2014 Jakraya Publications (P) Ltd 42
Srivastav and Kumbhar………..Modeling drying kinetics of Paneer using Artificial Neural Networks (ANN) data at all pressures for each temperature (Six ANN hidden layer. Each combination of hidden layers and models), combining all drying data for temperatures, neurons per hidden layer was trained. pressures and size (Six ANN models). Each data set Relative mean square error (MAE), Standard was divided in to two groups, consisting of 50% for deviation of MAE (STDA), Percentage of relative mean training and 50% for testing. During training, the data square error (% MRE) and Standard deviation of set was used to determine the optimum number of %MRE (STDR) and R2 along with number of hidden hidden layers, neurons per hidden layer that gave the layers and neurons in each hidden layer are reported for best predictive power. Architecture of artificial neural one set of data for illustration in Table 5. network was hidden layers 1 and 2 and neurons 3-9 per Table 2: Parameters of equations obtained from linear regression of drying data for different drying models Standard Deviation between observed and R2 Drying predicted moisture ratios Size of Pressure Temperature Generalized Page’s Generalized Logarithmic Paneer (0C) (kPa) Page’s Logarithmic exponential model exponential model model model model model Superheated Steam Drying 10 0.9945 0.9686 0.9100 0.0010 0.0145 0.0119 62 14 0.9934 0.9563 0.9739 0.0015 0.0109 0.0111 18 0.9961 0.9665 0.9735 0.0011 0.0086 0.0100 10 0.9859 0.9656 0.9155 0.0030 0.0171 0.0109 1.0.cm- 14 0.9934 0.9839 0.9767 0.0020 0.0116 0.0126 cube 72 18 0.9879 0.9683 0.9767 0.0031 0.0222 0.0114 10 0.9845 0.9350 0.9776 0.0041 0.0275 0.0145 14 0.9869 0.9674 0.9771 0.0036 0.0209 0.0145 82 18 0.9772 0.9569 0.9771 0.0043 0.0284 0.0120 10 0.9782 0.8455 0.9100 0.0025 0.0228 0.2862 14 0.9972 0.9880 0.9156 0.0016 0.0035 0.2931 62 18 0.9934 0.9823 0.9161 0.0020 0.0043 0.2754 10 0.9888 0.9556 0.9082 0.0014 0.0113 0.3052 1.5 cm- 14 0.9873 0.9860 0.9173 0.0017 0.0044 0.3048 cube 72 18 0.9939 0.9929 0.9171 0.0013 0.0062 0.2864 10 0.9917 0.9205 0.9094 0.0010 0.0208 0.3229 14 0.9939 0.9629 0.9198 0.0015 0.0176 0.3219 82 18 0.9953 0.9656 0.9203 0.0011 0.0130 0.3005 Table 3: Parameters of Page Equation (LPSSD) Temperature Pressure K N (0C) (kPa) 1cm cube 1.5 cm cube 1cm cube 1.5 cm cube 10 0.0041 0.0021 1.2209 1.3032 14 0.0038 0.0032 1.2152 1.2226 62 18 0.0050 0.0028 1.1568 1.2336 10 0.0054 0.0026 1.1960 1.2772 14 0.0050 0.0035 1.1917 1.2162 72 18 0.0054 0.0034 1.2005 1.2115 10 0.0062 0.0031 1.1843 1.2618 14 0.0061 0.0044 1.1805 1.1987 82 18 0.0067 0.0039 1.1552 1.1957 Journal of Food Research and Technology | January-March, 2014 | Vol 2 | Issue 1 | Pages 39-45 ©2014 Jakraya Publications (P) Ltd 43
Srivastav and Kumbhar………..Modeling drying kinetics of Paneer using Artificial Neural Networks (ANN) Table 4: Coefficients for Constants K' and N' of Paneer Dried With Low Pressure Superheated Steam For K' For N' Coefficients 1.0 cm-cube 1.5 cm-cube 1.0 cm-cube 1.5 cm-cube a1 5.625E-06 -3.594E-05 -2.119E-03 1.180E-03 a2 -1.750E-06 5.625E-06 3.754E-04 -1.738E-04 a3 9.375E-08 -2.031E-07 -1.569E-05 6.109E-06 b1 -9.050E-04 5.134E-03 3.099E-01 -1.810E-01 b2 2.845E-04 -7.963E-04 -5.520E-02 2.642E-02 b3 -1.475E-05 2.878E-05 2.308E-03 -9.290E-04 c1 4.590E-02 -1.874E-01 -1.006E+01 8.594E+00 c2 -1.211E-02 2.915E-02 2.018E+00 -1.059E+00 c3 6.010E-04 -1.051E-03- -8.443E-02 3.697E-02 In table 5 the minimum MRE was found with required to lower the error if there are enough number one hidden layers and nine neurons for moisture of neurons (Torrecilla et al., 2005). The best prediction content (dry basis), one hidden layers and five neurons for most of the data set contained two hidden layers. for drying rate and two hidden layers and seven ANN developed for combined drying data had slightly neurons for moisture ratio at 620C and 10kPa for 1.0 higher error than individual conditions. Minimum and cm-cube paneer. The results showed that the number of maximum error involved between actual and predicted hidden layers, and neurons per hidden layer, that values were 2.1657 – 3.929, 0.0555 – 0.0692 and yielded minimum error was different for each drying 0.0207 – 0.0416 for moisture content, drying rate and technique. A large number of hidden layers is not moisture ratio respectively. %db MR dm/dt Fig 3: Correlation between predicted and experimental values Journal of Food Research and Technology | January-March, 2014 | Vol 2 | Issue 1 | Pages 39-45 ©2014 Jakraya Publications (P) Ltd 44
Srivastav and Kumbhar………..Modeling drying kinetics of Paneer using Artificial Neural Networks (ANN) Plots of experimentally determined moisture Neural Network Model were fitted in the drying data. content, drying rate and moisture ratio versus ANN The empirical models were analyzed for best prediction predicted values for all combined data are shown in Fig of moisture ratio. The best models were selected on the 3. The correlation coefficients were greater than 0.98 in basis of maximum coefficient of determination (R2) all cases. For all combined data set with superheated and standard deviation (SD). ANN modeling was done steam, the R2 was found 0.9975, 0.9934 and 0.9983 for at two hidden layers (1 and 2) and nine neurons (3, 5, moisture content, drying rate and moisture ratio, 7, 9). The optimal ANN configuration was selected respectively. This shows that the ability of ANN to after calculating the statistical parameters like mean predict moisture content, drying rate and moisture ratio relative error (MAE), standard deviation of MAE was very good. (STDA), percentage of relative mean square error (%MRE) and standard deviation of %MRE (STDR). Conclusions Thus, ANN modeling can be successfully used for Empirical model namely page’s, generalized accurately predicting moisture content, drying rate and exponential and logarithmic models and Artificial moisture ratio. Table 5: Prediction of Drying Properties Drying No No (%)db dm/dt MR Conditions hidden neurons layer R2 R 2 R2 MAE STDA MRE STDR (%) MAE STDAMRE STDR (%) MAE STDA MRE STDR (%) 1 3 1.091 0.991 18.512 0.389 99.96 14.644 0.734 30.298 0.749 74.90 0.012 0.011 28.892 0.625 99.60 1 5 0.363 0.377 7.815 0.154 99.99 0.015 0.020 7.830 0.119 99.77 0.004 0.004 9.256 0.183 99.99 1 7 0.418 0.407 6.053 0.121 99.98 0.050 0.193 22.660 0.515 91.99 0.007 0.013 6.895 0.136 99.90 1 9 0.567 1.088 2.875 0.037 99.93 0.058 0.235 23.302 0.518 89.98 0.006 0.012 6.728 0.157 99.93 17, SS, 62, 2 3 0.869 0.583 12.756 0.168 99.96 0.030 0.081 19.991 0.423 97.49 0.009 0.007 29.824 0.602 99.93 2 5 0.430 0.339 5.798 0.071 99.99 0.019 0.024 19.466 0.456 99.51 0.003 0.003 5.666 0.090 99.99 2 7 1.078 0.717 21.322 0.389 99.96 0.014 0.017 19.418 0.512 99.81 0.011 0.007 3.523 0.620 99.97 2 9 0.608 0.594 21.853 0.447 99.98 0.018 0.024 19.920 0.476 99.53 0.006 0.006 37.060 0.087 99.94 References Borggard C and Thodberg HH (1992). Optimal minimal moisture content. Food Research International, 39: neural interception of spectra. Analytical Chemistry, 64: 1110-1118. 545 551. Nema PK, Mohapatra D, Daniel A and Mishra S (2013). Devahastin S, Suvarnakuta P, Soponronnarit S and Mujumdar Modeling pulse microwave drying kinetics of ginger AS (2004). A comparative study of low pressure (Zingiber officinale R.). Journal of Food Research and superheated steam and vacuum drying of a heat- Technology, 1(2): 46-58. sensitive material. Drying Technology, 22(8): 1845- Ruan R, Alamer S and Zhang J (1995). Prediction of dough 1867. rheological properties using neural networks. Cereal Deventer HC Van and Heijmans MH (2001). Drying with Chemistry, 72(3): 308-311. superheated steam. Drying Technology, 19(8): 2033- Shihani N, Khumbhar BK and Kulshreshthra M (2004). 2045. Modeling of extrusion process using response surface Fang Q, Hanna MA, Haque E and Spillman CK (2000). methodology artificial neural network. Journal of Neural network modeling of energy requirements for Engineering Science and Technology, 1(1): 31-40. size reduction of wheat. Transactions of American Shrivastav S and Kumbhar BK (2009). Modeling and Society of Agricultural Engineers, 43(4): 947-952. optimization for prediction of moisture content, drying Farkas I, Remenyi P and Biro A (2000). Modeling aspects of rates and moisture ratio. International Journal of grain drying with a neural network. Computers and Agriculture and Biology Engineering (Beijing), 2(1): Electronics in Agriculture, 29: 99-113. 58-65. Huang B and Mujumdar AS (1993). Use of neural network to Srivastava S and Kumbhar BK (2010). Textural profile predict industrial dryer performance. Drying analysis of paneer dried with low pressure superheated Technology, 11(3): 525-541. steam. Journal of Food Science and Technology, 47(2): Islam R, Sablani SS and Mujmudar AS (2003). An artificial 355-357. neural network model for prediction of drying rates. Srivastava S and Kumbhar BK (2013). A Comparative study Drying Technology, 21(9): 1867-1884. of low pressure superheated steam (LPSS) and vacuum Kerdpiboon S, Kerr SL and Devahastin S (2006). Neural drying (VD) of paneer. Agricultural Engineering network prediction of physical property changes of Today, 37(2): 7-13. dried carrot as a function of fractal dimension and Susan L (1998). Experts systems-what can they do for the food industry?. Food Science and Technology, 9: 3-12. Journal of Food Research and Technology | January-March, 2014 | Vol 2 | Issue 1 | Pages 39-45 ©2014 Jakraya Publications (P) Ltd 45
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