International Journal of Advanced Engineering Technology E-ISSN

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1 Research Article OPTIMIZATION OF RICE FLOUR (ORYZA SATIVA L) AND LALI (METAPENAEOPSIS STRIDULANS) EXTRUSION BY RESPONSE SURFACE METHODOLOGY Mahuya Hom Choudhury*, Runu. Chakrabarty, Utpal Raychaudhuri Address for Correspondence Department of Food Technology & Biochemical Engineering, Jadavpur University, Kolkata-India ABSTRACT E Mail mhc_123@rediffmail.com Lali (Metapenaeopsis stridulans) powder and rice flour mixture was used as base material for extrusion process. The process was optimized using response surface methodology (RSM). Response (dependent) variables were: expansion ratio, density, shearing strength and sensory texture acceptability. Independent variables were processing temperature and feed moisture. All other process variables (screw speed, feed speed and die diameter) were kept constant (475 r.p.m, 28 g/min and 3 mm respectively). The most expanded products had the best texture and which were obtained at 150 C and 15% moisture containing of feed material. This study showed that under condition that induced the maximum expansion produce best texture and highest acceptable snack product based on rice and lali flour. KEYWORD: Shrimp, protein, extrusion, expansion ratio, response surface, glass transition. INTRODUCTION Lali (Metapenaeopsis stridulans) a local variety of shrimp has been used as food items in the coastal areas of West Bengal, India. Lali contains 20% protein, 1% fat, 76% moisture, 1.5 % ash and a good amount of minerals. (USDA National Nutrient Database for Standard Reference, Release 15, 2002). A large amount of lali is wasted every year due to lack of proper preservation measures. Extrusion process has been proposed as an effective solution to improve digestibility and keeping quality by removing antinutrients at the same time. (E.A. Abd El-Hady & Habiba, 2003). Extrudates exhibits better nutritional quality compared to other traditional cooked products (Bressani et al, 1992, Singh et al 2007). Considering advantages of twin screw extrusion process, coastal lali and rice flour mixture were extruded to improve the nutritional quality of extruded product and to study the related functionality of complex carbohydrate and shrimp-protein mixture. Response Surface Methodology (RSM) has been successfully applied for optimizing conditions in extrusion cooking process (Batistutti et al 1991; Vargas-Lopez et al 1990,Banerjee.S et al,1997, Yong Wang et al,2008). In present study, the process condition was optimized using Response surface Methodology. In general, a high expansion index and firm textures are desirable qualities for ready to eat breakfast snacks. Thus, the objective of the present work is to study the relationship between extrusion cooking parameter and product quality, and thereby find out the optimum conditions for an extruder to produce a rice and shrimp protein based snack food. MATERIALS AND METHOD Materials: Rice (Oryza sativa L), Table Salt (2%) were procured from local market and lali (Metapenaeopsis stridulans) collected from coastal areas of West Bengal. Proximate Composition: Proximate composition was analysed using standard method (AOAC, 2002) Preparation of Sample: Lali collected from coastal area was washed thoroughly in fresh water and the water was drained and then it was dried in an oven (800 W

2 grill oven Sanyo, JP) at 60 C for 2 hours. Rice collected from local market was also washed and dried at the same condition. After the water was completely removed, dried shrimp and rice were finely ground into powder form (40 mesh) with a blender (Mixer Grinder, Bajaj,GM-550) separately. Rice and lali powder was mixed (5:1). The moisture was adjusted to 11%, 13%, 15% and 17% adding the required amount of water to the flour mixture and conditioned at room temperature for 48 hours. The flour was sealed in polyethylene bags & stored at 4 C in refrigerator. Moisture content: Moisture content of control and extruded products were measured using standard air oven (Model No-06104, SC Dutta & Co, Kolkata) according to AOAC, Extruder & Extrusion cooking: A co rotating fully intermeshing twin screw extruder was used (screw profile 12:1 barrel length 350 mm; barrel bore diameter 38 mm; screw diameter 37.8 mm; conveying angle 30 ; intermeshing screws 24 mm apart) for extrusion of the feed mixture using a 3 mm diameter die. The screw speed of the extruder was set at 475 rpm, while the feed rate was maintained constant at 28g/min. The extruder started functioning properly with said feed mixture at 110 C and at 11% feed moisture condition and totally stopped after 170 C and at 19% feed moisture condition. The temperature of the extruder at the time of product discharge was noted at 110 C, 130ºC, 150 C &170 C respectively Product temperature was maintained at 50 C by circulating cooling water and temperature was controlled electrically. Optimization: The process was optimized using Response Surface Methodology (RSM) for maximum values of expansion ratio, sensory texture acceptability, and minimum value of shear strength and density for extrudates. Initial experiments at feed moisture of 10 to 20% (d.b) and end Zone temperature at the time of product discharge was noted of ºC, showed that a good expansion could be obtained at around 150ºC and 15% moisture. Preliminary experiment shows that minimum feed moisture and process temperature for proper operation was 11% and 110 C. Based on these preliminary experimental data a central composite design was formed with five level of variation of temperature and moisture (1, -1,0,2, -2) (Cochran and Cox 1957;Myers 1971;Box and others 1978; Akhnazarova S, Kafarov V. 1982). The experimental matrix is shown in Table 2.The nine experimental points (1,-2), (-2,-2), (-2,-1), (-1,1), (1,1), (-1,-1), (1,-2), (-2,1), (1,-1) formed a 2 2 full factorial design. The six additional axial points (0,-1), (0,-2) (0,1) (-1,0), (1,0), (-2,0) enlarged the region of dependency. One central point (0,0) completed the central composite rotatable design (Barros and others 1987 Bastos and others 1991; Batisuti and others 1991). Regression analysis fitted the result to second order polynomial. STATISTICA for Windows Release 9 Copyright, Stat Soft Inc was used for statistical calculations and graphical analysis. The polynomial stated was: Z=B O + B 1 X 1 + B 2 X 2 + B 11 X B 22 X B 12 X 1 X 2 +E Where z=dependent variable (Expansion ratio, shear strength, ratio of shear strength to extrudate diameter, density, or sensory acceptance of the texture): X 1 = Feed moisture; X 2 =Temperature of the central Zone of the barrel; E= Experimental error with normal distribution.

3 Expansion ratio: Expansion ratio was determined as the ratio of extruded product diameter to the diameter of the die. Values reported were averages of 30 measurements in each temperature and moisture combination as reported in optimization section. Density: The density (ρ, mg.mm -3 ) was calculated as ρ=4m/πd 2 L where M= mass average of extrudate in mg (mean of 30 weighing in an analytical balance); D= diameter of the extrudate(mean of 30 measurements with vernier Caliper) in mm and L= Average length of extrudate in mm (mean of 30 measurements with a vernier caliper). Shear strength: A universal Texture Analyzer (model-4301 Instron London, UK) was used in compression mode to record the required force to break extruded products. The extruded samples (5cm long) was placed on the platform transversally over a metal sheet support (1cm. thick) and operated in a compression mode with a sharp testing blade (3mm. Thick, 6.93 mm wide). The texturometer head moved the probe down at a rate of 15 mm/min until it broke the extrudates. Values reported were averages of 30 measurements in each temperature and moisture combination as reported in optimization section using load of 50N. Texture Acceptability: To evaluate the sensory acceptance of the extruded product, a scale of 100 mm long was used (Land and shepherd 1988). The texture acceptability score was defined as the distance from origin of the mark assigned on the scale by panelists relative to the central point on the scale which was assigned as the acceptability score of reference product (a commercial brand of unflavoured extruded corn). The panelist was instructed to consider only the texture and ignore the color and flavor. Every panelist assessed the texture with reference to relative texture acceptability of a standard sample coded with the letter p, and asked to indicate the score on the ballot. Statistical Analysis: The analysis of variance (ANOVA) was carried out based on the experimental data using STATISTICA for Windows Release 4.5 A Copyright, Stat Soft Inc The statistical significance of the terms used in the regression equation was also examined. RESULTS AND DISCUSSION: Physical properties of extruded The physical properties of the rice and lali extrudate obtained from 16 measurements and the effect of independent and response variables of extruded are presented in Table 2. The products with the highest expansion ratio had the most appropriate texture for consumption and obtained at 150 C and 15% moisture. Thus the greater the expansion, the lower is the shearing force and at the same time the less is the shear stress and the greater is the textural sensory acceptability observed for the extrudate, obtained at the mentioned temperature and process moisture. ANOVA of expansion ratio in Table 3 shows significant effect of process temperature and moisture on response variables. Proximate composition: Proximate composition of rice and lali are as follows respectively: moisture 13.0%, 76%; protein 6.9%, 20.1% fat 0.4, 1%, Carbohydrate 79.0, 0.0; ash 0.5, 1.5% respectively. Table 1 represents proximate analysis raw and extruded snack.proximate analysis shows lali could be used for preparation of nutritionally superior extruded foods with protein enrichment.

4 Table 1: Proximate composition of Rice and lali extrudate Material Moisture (%) Protein(%) lipids(%) Rice flour Lali flour Extruded flour Table-2: Specification matrix of the second order design and result of the effect of independent and response variables of rice and lali extrusion Assay Independent Variable Response Variable n a X 1 (x 1-150) /20 X 2 (x 1-15) /2 X 1 (T C) X 2 (% moisture db) Expansion Ratio Y 1 b Shear force (N) Y 2 c Shear Stress (N/m 2 ) Y 3 d Density (mg. mm -3 ) Y 4 e Acceptance of Texture (mm in a 100 mm scale) Y 5 f

5 Continue from the previous page a does not correspond in order of processing b-f Average of 30 measurement ANALYSIS USING RESPONSE SURFACE Y 1 = 0.159X X X 1 X X METHODOLOGY: Expansion Ratio: The most expanded extrudates were obtained at 150 C and 15% moisture. The data for significant linear, quadratic and interaction terms for multiple regression analysis of variance for the full regression is represented in Table 1. The variance analysis for these data revealed a determination coefficient (r 2 ) greater than 0.90 (r 2 =0.91). An agreement of 90% is expected for second order polynomial model for food extrusion.( Aguilera and Kosikowsiki, 1976). The result obtained for expansion ratio indicated that the experimental error is kept to a minimum. The results showed that linear and second order effects of temperature and moisture were significant (p<0.05) (Table 3). The resultant polynomial for this variable was: 0.031X The response surface for this variable is presented in Fig 1. Result shows expansion ratio of final product increases with increasing moisture and temperature up to a limiting value and then decreases. The predictive equation obtained for these analyses, allowed a range of products with variable characteristics attending the various consumption standard to be obtained. Fig. 1 shows the extrudate for all temperature and moisture condition assayed. More uniform texture and the most expanded products are obtained at 150º C. and 15% moisture. The present work showed that lali presented a typical response surface behaviour of proteinaceous material with a region of maximum expansion ratio for feed moisture content and temperature noted at the time of product discharge.

6 Figure 1: Response surface for the effect of feed moisture and process temperature on expansion ratio of rice-shrimp (lali) protein extrudate Table 3: ANOVA for the effect of feed moisture and process temperature on expansion ratio of rice and shrimp ANOVA (r 2 =0.92) df SS MS F Regression Residual Total Coefficients Standard Error t Stat P-value Intercept E-18 X Variable E-06 X Variable

7 Shear strength: Fig 2: explains response surface for the effect of feed moisture and process temperature on force to completely shear rice and shrimp (lali) protein mixture extrudate. The shear strength of the extruded samples was also determined and the minimum force to shear completely the sample was obtained at the central point (15% moisture and 150ºC). The r 2 for this variable from the variance analysis of the multiple regression for the polynomial model, was 0.84 (p<0.05). The multiple regression showed significant quadratic effect of moisture and temperature. 2 Y 2 = X X 1 X X X X The greater is the expansion volume the lower is the shear strength. (Chinnaswamy and Hanna 1988). In the present study, the most expanded, greatest volume and lowest stress were obtained at 150ºC barrel temperature and 15% moisture. Shearing Stress: When the shearing force was divided by the extrudate area to obtain shearing stress (N/m 2 ) a minimum value was obtained at the central point (15% moisture and 150 C barrel temperature). The r 2 for this variable from the variance analysis of the multiple regression for the polynomial model, was The multiple regression showed significant quadratic effect of moisture and temperature (p<0.05). The resultant polynomial for this variable was: 2 Y 3 =11460X 1 X X X X X Fig. 3 explains the response surface for the effect of feed moisture and process temperature to completely shear the extrudate. Fig 2: Response surface for the effect of feed moisture and process temperature on force to completely shear rice- lali extrudate

8 Fig 3: Response surface for the effect of feed moisture and process temperature on ratio force to completely shear the sample of rice -lali extrudate Density Fig 4 represents response surface for the effect of feed moisture and process temperature on density of rice shrimp (lali) protein mixture extrudate. The determined density of the extrudates varied between mg.mm 3. The surface figure shows the response surface as a function of feed moisture and process temperature. The result indicated that linear effects of both moisture and temperature and second order effect of moisture and temperature were significant (p<0.05) and r 2 = The resultant polynomial for these variables were: Y 4 = X X X 1 X X X 2 2 The surface presented in fig. 4 also shows decrease in density with an increase in process temperature and moisture. Lowest density was observed at 150 C and 15% process moisture condition. For starchy system, Gomez and Aguilera (1984) found that puffing was directly related to temperature and inversely related to moisture. Thus, here also, typical response surface behaviour of proteinaceous material was observed for the density analysis of the extrudates. Acceptability of texture: Fig 5 represents response surface for the effect of feed moisture and process temperature on acceptance of texture of the extrudate. The multiple regression analysis for texture acceptance showed second order effect of moisture, temperature and the interaction term (p<0.05). The determined r 2 was 0.88 and the resultant polynomial for this variable was: Y 4 =4.691X X X 1 X X X

9 Fig 4: Response surface for the effect of feed moisture and process temperature on density of rice-lali extrudate Fig 5: Response surface for the effect of feed moisture and process temperature on acceptance of texture of rice lali extrudate

10 The maximum sensory acceptance of the texture of the snack product was obtained in the samples processed at 15% moisture and 150ºC process temperature, where in fact, maximum scores were assigned by panelist, indicating higher acceptance of the texture compared to standard, (a commercial brand of unflavored extruded corn). Also greater the expansion, the lower the shearing force, and less the shear stress, and the greater the textural sensory acceptability. CONCLUSION: The optimization of carbohydrate-protein extrudate shows a typical response surface behaviour where the expansion ratio shows an increase linear as well as in quadratic pattern with the change of process moisture and process temperature condition. The optimization process also presents a characteristic surface behaviour of complex food system for expansion ratio, density, shear force, shear stress and texture acceptance of extrudate. This study thus demonstrates that shrimp of lali variety can be extruded and used as high quality protein snack food in place of corn based snacks. In the optimal process, the maximum expansion ratio obtained at 15% moisture and 150ºC process temperature coincided with the minimum shearing force of the product, and maximum sensory texture acceptance indicating a correlation between extrusion response variables. Response surface study indicated the desired texture and sensory property could be obtained by controlling cooking temperature and moisture condition. ACKNOWLEDGEMENTS: We gratefully acknowledge Central Research Facility, Indian Institute of Technology, Kharagpur and Dr. Subhas Mukherjee Memorial Research Institute, Kolkata, Basic Technology Kolkata, providing us technical and instrumental support for carried out the research work. REFERENCE: 1. Aguilera J M, Kosikowski FV. (1976), Soybean extruded product: a response analysis, Journal of Food Science 41: Akhnazarova S, Kafarov V. (1982), Experiment optimization in chemistry and chemical engineering, Moscow, Mir Publishers. 312 p 3. AOAC Methods of Analysis, 15 th edn. (2002), (AOAC,Washington DC). 4. Barros RMC, Sliva RSF, Borsato D, Areas JAG.(1987) Otimizacao das condicoes de extrusao de soja pelo empergo de metodoloogia de superfficie de resposta. Bol. Centro.Pesqui. Processos. Aliment. 5(2): Banerjee Soumitra and Chakrabarty Pratap (Apr- Jun, 1997), Production of Extruded prawn feed, Indian Journal of Fish 44 (2), Bastos DHM. Domenech CHL Areas JAG (1991). Optimization of extrusion cooking of lung protein by SEM International Journal of Food Science & Technology, 26: Batistuti JP, Barros RMC Areas JAG (1991). Optimization of extrusion cooking process for Chickpea (Clcer arietinum L ) defatted flour by response surface methodology Journal of Food Science.56: Box GEP, Hunter WG, hunter JS.(1978) Statistics for Experimenters. An Introduction to Design, data analysis and model building, New York: Willey 669p 9. Bressani R. Sancher Marroquin A. Morales E. (1992). Chemical composition of grain amaranth cultivars and effects of processing on their nutritional quality. Food Review International, 8(1) Chinnaswamy R. Hanna M.I. (1988). Optimum extrusion cooking conditions for maximum expansion of corn starch.journal of Food Science.53(3): Cochran WG, Cox GM (1957). Experimental Designs 2 nd ed. New York : Wlley, 611p. 12. E.A. Abd El-Hady and R.A. Habiba, Effect of soaking and extrusion conditions on antinutrients and protein digestibility of legume seeds, Lebensmittel-Wissenchaft u-technologie 36 (2003), pp Gomes MH, Aguilers J M (1984). A physicochemical model for extrusion of corn starch Journal of Food Sciences 49: Land DG, Shepherd R, (1988) Scaling and ranking methods. Ch.6. In. Sensory analysis of foods, Piggott JR, editor, New Work. Elsevier Science Publishing Co.,pp

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