Formulation Optimization of Cookies from Different Levels of All- Purpose, Soybean (Glycine max (L) Merr) and Nami (Dioscorea hispida Dennst) Flour

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1 Journal of Science, Engineering and Technology 5:69-81 (2017) Southern Leyte State University, Sogod, Southern Leyte, Philippines Formulation Optimization of Cookies from Different Levels of All- Purpose, Soybean (Glycine max (L) Merr) and Nami (Dioscorea hispida Dennst) Flour Ma. Carisse M. Compendio Lorina A. Galvez* Department of Food Science and Technology Visayas State University Visca, Baybay City, Leyte, Philippines Abstract Cookies can be considered as a nutrition-vehicle for children since it can be a good source of higher nutrients and more functional food property needed by them. This study was conducted to optimize the formulation of cookies from different levels of all- purpose, soybean and nami flour. nami was subjected first for detoxification process. A 2, 3 Simplex Lattice Design was used in this research with all- purpose, soybean and nami flour as the independent variables. Sensory evaluation of the ten treatments was done using Incomplete Block Design. The data were subjected to optimization study and verified. The optimum treatment was subjected to consumer preference test and proximate analysis. Results of the detoxification process revealed that nami flour is safe to be used for cookies production due to absence of alkaloid. Results of the sensory acceptability revealed that cookies were significantly affected by varying levels of all-purpose flour, soybean and nami flour. The optimum formulation of the cookie product has a level of 25.89% w/w all- purpose flour, 31.25% w/w soybean flour and 42.86% w/w nami flour at the cost of Php 6.20/30 grams cookies. Verification study revealed that the model equations generated were reliable in predicting all of the attributes except aroma. Consumer preference test showed that the optimum product can compete in the market with the existing commercial counterpart product. The optimum cookie formulation has 8.47% crude protein, 0.27% fiber, 19.83% fat, 1.08% ash, 94.11% dry matter and 5.90% moisture content. Keywords: All-purpose flour; celiac disease; cookies; dioscorine; gluten; Nami (Dioscorea hispida Dennst); protein energy malnutrition; soybean flour Introduction Dioscorea hispida Dennst, or bitter yam or nami in the Philippines is one of the most economically important yam species that serves as staple food for millions of people in tropical and sub-tropical countries ( Udensi et al., 2008). It has been considered as an important source of carbohydrates but rarely eaten by natives nowadays because it requires a lot of time and effort to prepare (Liu et. al, 2006). It contains neurotoxic dioscorine, an isoquinuclidine alkaloid that causes nervous system paralysis (Sasiwatpaisit et al., 2014). Nami contains resistant starch that has been related with slow digestion in the lower parts of the gastrointestinal tract which results to slow liberation and absorption of glucose. Due to its digestive property, the utilization of this tuber has been suggested to reduce the risk of obesity, diabetes and other related diseases (Aprianita et al., 2009). In addition, *Correspondence: lorina.galvez@vsu.edu.ph ISSN

2 nami does not contain any gluten, which makes it become an important substance in the reduction in the incidence of Celiac disease (CD) or other allergic reactions (Rekha, 2002). With these benefits in mind, this tuber can also be processed into edible food products like flour after the toxic alkaloid compounds are properly removed. Flour can be ground from variety of edible grains such as nuts, seeds or even roots. Although there are many types of flour, all-purpose (or occident) flour is used most frequently. It contains iron and four B- vitamins (thiamin, niacin, riboflavin and folic acid). Its protein content also ranges from 8-11% (Michaelides, 2009). Soybean which is a good source of protein shows more health benefit. The nutritional profile of beans shows that they are high in protein, low in saturated fat, and high in complex carbohydrates and fiber. Soybeans are a concentrated source of isoflavones. Soy foods and isoflavones have received considerable attention for their potential role in preventing and treating cancer (Messina, 1999, and Messina, 2003). Soy flour, derived from ground soybeans, boosts protein, brings moisture to baked goods, and provides the basis for some soymilks and textured vegetable protein. This versatile ingredient improves taste and texture of many common foods and often reduces the fat absorbed in fried foods. Soy foods have high quality of protein that contains all essential amino acids needed for growth (Shurtleff, 2002). Protein-energy malnutrition (PEM) remains the leading nutritional problems in the Philippines. In fact, except for protein, the typical Filipino diet was found to be grossly inadequate for energy and other nutrients. In order to compensate for the inadequate energy intake, the body utilizes protein as energy source (Fanzo, 2010). Cookies, a major flour product in which various ingredients are used including sugar, flour, eggs, butter and other ingredients which will be baked into small products, are considered as one of the convenient and palatable food perceived by children and adults. Children s diet nowadays are often poor (Ogden, 2003) due to higher intakes of unhealthy foods. Snack foods are often eaten in between meals, and can be sources of either conflict or pleasure unless this food becomes a good source of higher nutrients needed by children. It is therefore important that in processing cookies raw materials that are nutritious and have functional properties should be utilized for the benefits of the children as well as other consumers who love cookies. The combinations of these raw materials however, should be optimized to make sure higher acceptability. In achieving this goal Response Surface Methodology (RSM) can be used to find improved or optimal process settings, troubleshoot process problems and weak points, and make the product process more robust against external and non-controllable influences (Giovanni, 1983). It combines design of experiments, regression analysis and optimization methods in general purpose strategy to optimize the expected value of stochastic response (Barton, 2016). RSM can also be applied in the design, development and formulation of products as well as in the improvement of existing product designs (Myers et al., 2009). Therefore, this study was conducted to determine the optimum level of flours from nami, all-purpose and soybean to be incorporated into the formulation of cookies without negatively affecting its acceptability. Methodology Detoxification of Nami In detoxifying nami the method of Dela Rosa (1985) was followed which comprised of washing, peeling, slicing, weighing and addition of 10% salt and mixed well. The nami was soaked in a brine solution for 12 hours. After soaking, the mixture was washed with running water for 24 hours and dried for 8 hours at 68 C. 70

3 Quantitative Alkaloid Determination of Nami Before and After Detoxification Following the method used by Harborne (1973), 5 grams of the sample was weighed into a 250 ml beaker and 200 ml of 10% acetic acid in ethanol was added. It was covered and allowed to stand for 4 hours and was filtered. T he e xtract w as concentrated on a water bath to one- quarter of the original volume. Concentrated ammonium hydroxide was added drop wise to the extract until the precipitation was complete. The whole solution was allowed to settle and the precipitate was collected and washed with dilute ammonium hydroxide and was filtered. The residue was now the alkaloid, which was dried and weighed. Preparation of Nami Flour The detoxified d ried n ami c hips w ere milled three to four times to achieve fine particles which are best for flour. N ami flour was then stocked inside airtight jars ready for use. added to it and was mixed until thoroughly combined. The dough was placed on an icing bag and was pipe off on the baking sheets. It was baked for minutes. After cooking, the product was cooled in a room temperature area and was now ready for sensory evaluation. Experimental Design A 2, 3 Simplex Lattice Design was used in this research. Figure 1 shows the experimental design that was used with 10 treatments for experimental combinations with all- purpose, soybean and nami flour. Preparation of Soybean Flour Soybeans were soaked in water overnight and were dehulled after. The dehulled soybeans were dried in tray driers until brittle and were also milled five t o t en t imes t o e nsure the resulting texture was fine since soybeans were tougher than nami. Preparation of the Cookie Product The necessary ingredients were prepared like nami flour, s oybean fl our, al l-purpose flour, baking soda, egg, salt, sugar, margarine, lard, and vanilla. The oven was preheated to 360 o F while sifting all the dry ingredients in a small bowl except the sugar. It was mixed well. In another bowl, butter and sugar were beaten using electric mixer on a medium speed until the texture becomes light and fluffy. Vanilla and egg were added to the mixture and were beaten in a low speed. Flour mixture was Figure 1. Experimental design for mixture surface analysis Sensory Evaluation Acceptability of the product was evaluated in terms of color, taste, aroma, texture, flavor, oiliness and general acceptability using descriptive scoring and 9- point hedonic scale with the scores of 1- dislike extremely to 9- like extremely. The samples were coded randomly with 3 digit numbers and were evaluated by 60 panelists who were Junior and Senior BS Food Technology students (Mabesa, 1986). Incomplete Block Design (IBD) was used for the sensory evaluation and a total of ten samples were tested as set by Cochran and Cox (1980). The set plan of t=10, k=6, r=9, b=15, χ= 4 E=0.93, Type III was followed where t refers to the number of treatments, k refers to the number of samples to be 71

4 Table 1. Different levels of the main component of cookies in percent (%w/w) Treatments All Purpose Flour Soybean Nami Flour (%w/w) Flour(%w/w) (%w/w) presented to the panelist, r was the number of replications based on the plan IBD, b was the number of blocks, χ is the number of times the set plan was replicated and E was the efficiency factor. The set plan was done 4 times to make a total of 60 panelists, evaluating 6 treatments at a time producing 36 observations per treatment. Another sensory evaluation was carried out using the same experimental design for the second replicate. Statistical Analysis Response Surface Regression (RSREG) analysis was employed using STATISTICA version 8 software in the analysis of the sensory acceptability for all of the treatments for optimization study. The statistica 8.0 software was also used in the generation of the graphical presentation of the response surface plots. Paired t-test was used to verify the models generated in all sensory attributes for the optimum formulation. Chi-square test was employed to determine the significance of the preference of the consumers. Cost Analysis Market prices of the used ingredients during the study were noted down to determine production cost. Labor and all other expenses that were used during the processing were also included for cost determination. Optimization Optimum combination of all- purpose, nami and soybean flour in cookies formulation was obtained by generating a contour plot for all sensory attributes on the ternary graph. A minimum acceptability score was determined for each sensory attributes and was plotted with lines as the acceptability level was overlaid to determine the optimum region for its sensory acceptability. Any point within the region was considered optimum. Verification A rerun of the optimum formulation was conducted to validate and determine the predictive ability of the model equations generated for each parameter. The sensory evaluation employed 30 panelists. Results were analyzed using paired t-test to compare the predicted and observed values of the optimum formulated cookie product. Consumer Preference Test Optimum combination of the three components that was determined went through a consumer preference test to determine consumers preference between the formulated product and commercial cookie product. Samples were given to the consumers composed of 25 elementary students (aged 7-12), 25 high school students (13-16 years old), 25 college students (

5 years old) and 25 professionals/adults (22-52 years old) for them to choose and to indicate their most preferred product. Results were subjected to chi- square test to assess the difference between the commercial and formulated product. Proximate Analysis The cookie having the optimum condition was subjected to proximate analysis (Moisture content, Protein, Crude Fat, Ash, and Crude Fiber) to determine its composition. Results and Discussion Alkaloid Amount Nami tubers were tested for the presence of alkaloid before the detoxification process and after flour processing. Results of the detoxification process revealed that nami flour is safe to be used for cookies production as implicated by the absence of alkaloid after detoxification. The amount of alkaloid before detoxification was g and after detoxification, none was found showing that detoxification process was successful. Sensory Evaluation Sensory attributes which include color, texture, taste, oiliness, aroma, flavor, and general acceptability were analyzed using Response Surface Regression. Table 2 shows the summary of the analysis of variance (ANOVA) for the different sensory attribute of the formulated cookies. Parameter estimates on the sensory attributes between all- purpose, soybean and nami flour and its combinations is presented in Table 3. Color Color is one of the most important factors that can influence the consumers acceptability of a food product. It is also considered as a promotional strategy because it can attract possible consumer. Color intensity of the formulated cookies was affected by the different levels of all- purpose, soybean and nami flour being used as a main ingredient. The comparison of the color acceptability of the cookies as affected by different levels of all- purpose, soybean and nami flour is shown in Table 4. Mixtures having high level of soybean flour were observed by the panelists to be yellowbrown in color while the treatments with high levels of all- purpose and nami were perceived to be pale- brown to brown in color. Color intensity of the formulated cookies was mostly imparted by the level of soybean flour incorporated since its flour color ranges from tan to yellowish- brown. Color acceptability ranged from 6.33 to 7.76 with an overall response mean of 7.39 that falls within the like moderately category of 9- point Hedonic scale. Cookies produced with high levels of nami flour were less acceptable as presented in Table 4. Color acceptance rating increases if more all- purpose flour is added into the flour mixture and decreases as the amount of nami and soybean flour increases. Parameter estimates (Table 3) reveal that soybean and nami flour has a quadratic effect on the color acceptability of the cookies produced. It indicates that cookies composed of only one type of flour as a main component in the treatment has a highly significant effect on the color acceptability of the cookies. The effect of the combination of nami and soybean flour in the mixture was observed to be quadratic and significant. Higher acceptability rating will be achieved if nami flour is combined with all- purpose flour since panelists tend to give higher acceptability rating to white cookies. This implicates that creamy white color of nami flour will be offset by the addition of allpurpose flour which is white. Aroma Aroma is the gauge to measure the quality of food since it gives a signal whether the food is preferable or not (Kubota, 2007). The cookies 73

6 Table 2. Analysis of Variance (ANOVA) for the different sensory attributes of soybean-nami cookies **highly significant at <0.01, *significant at <0.05, ns not significant Table 3. Parameter estimates for the sensory attributes of the formulated cookie product from the different levels of all-purpose, soybean and nami flour **highly significant at <0.01, *significant at <0.05, ns not significant AP- All- purpose Flour, SB- Soybean Flour, NM- Nami Flour Table 4. Mean acceptability ratings of color of formulated cookies as affected by different levels of all- purpose, soybean and nami flour Treatments Color Aroma Taste Flavor Texture Oilness Gen. Acc Overall response mean N= 72 observations 74

7 produced were described by the panelist as having a well- blended soybean and nami aroma. According to Rackis et al. (1979) as cited by Koyabashi et al. (1995) soybean has a beany and grassy- off aroma which is due to the C6 alkyl- or alkenylaldehydes which are formed by oxidation and breakdown of unsaturated fatty acids molecule. Analysis of Variance (ANOVA) shows that aroma acceptability is found to be significantly fit to the linear model of the response (p<0.01) (Table 2). Acceptability rating will increase if more all- purpose flour will be used and relatively decreases as the amount of soybean and nami flour will be used (Table 4). Due to soybean s pungent aroma and nami s unfamiliar odor, panelists tend to rate cookies with all- purpose flour higher than other mixtures. Parameter estimates (Table 3) also shows that the aroma acceptability of the cookies is not significantly affected by the combination of at least two types of flour. This means that the decrease in the aroma acceptability of the product is imparted by the distinct odor of nami and soybean flour can be offset if it will be combined with all- purpose flour. Taste Taste is one of the most important factors in determining food selection; it is detected by the tongue when saliva surrounded food particles touch gustatory cells that send signals to the brains which differentiate tastes. Taste of the cookies produced varies only from slightly sweet to moderately sweet having an acceptability rating of 6.74 to 7.85 with an overall acceptability rating mean of 7.4 which falls closely to like moderately (Table 4). Data show that an increase of soybean and nami flour has a negative effect on the taste acceptability rating. Thus, increasing their level on the flour component of cookies will result to low acceptability rating. Panelist favors the taste of all- purpose flour since soybean has a beany flavor which alters the taste of the cookies. Nami, on the other hand, gives a very unfamiliar taste to the panelist thus, gaining low acceptability. Analysis of Variance (Table 2) shows that combination of all- purpose- soybean flour and soybean- nami flour has a significant quadratic effect on the taste of the cookies which means that in order to improve the taste acceptability of the cookies using soybean flour, it should be combined with either nami flour or all- purpose flour in the formulation. Flavor Flavor is the sensory impression of food or other substance, and is determined primarily by the chemical senses of taste and smell. For the flavor attribute, panelists perceived the cookies from T 2 as moderately pronounced soybean, T 3 as moderately pronounced nami and T 1, T 4 to T 10 as well- blended soybean and nami. Mean acceptability rating of the different treatments ranges from 6.71 to 7.94 with an overall mean acceptability rating of 7.42 which is like moderately as shown in Table 4. Results revealed that acceptability rating tend to increase if more all- purpose flour will be used and relatively decreases as the amount of soybean and nami flour will be incorporated in the flour mixture. Soybean s beany flavor and nami s unfamiliar taste causes the panelists to rate cookies with higher levels of all- purpose flour higher than other mixtures. Parameter estimates (Table 3) show that the flavor acceptability of the cookies is significantly affected by the combination of soybean and nami. Addition of nami flour on soybean flour in the formulation can offset its beany flavor which can increase the flavor acceptability of the product. Statistical analysis as reflected in Table 2 indicates that flavor acceptability is found to be significantly fit to the linear and quadratic model of the response of soybean and nami flour. Parameter estimates (Table 4) reflect that mixtures with only one type of flour as a main component in the treatment has a highly significant effect on the flavor acceptability of the cookies as well as the mixture with soybean and nami flour 75

8 as its main ingredient. Nami and soybean combination has a positive quadratic effect on the cookies flavor. It revealed that flavor acceptability is not significantly affected by the binary combination of all- purpose to the other two types of flour. Texture Food texture is defined as those properties of a food that are sensed by touch in the mouth and with the hands. It is important to the enjoyment and acceptability of foods. Cookie texture of the different treatment varies from soft but crispy to very crispy with a mean acceptability rating ranging from 7.01 to 8.04 with an overall mean acceptability rating of 7.56 which falls to like moderately (Table 4). Treatments with high levels of nami flour were described by the panelists as soft but crispy while treatments with high levels of all- purpose and soybean flour were perceived as either crispy or very crispy. Acceptance rating (Table 4) of the texture increases as the amount of all- purpose flour approaches to 100% and decreases as the amount of nami and soybean flour increases. Analysis of variance (Table 2) indicates that texture acceptability is significantly fit to the linear (p<0.01) and quadratic (p<0.05) model of the soybean and nami response. Parameter estimates as shown in Table 4 reflect that treatments with only one type of flour as a main component in the formulation has a highly significant effect on the texture acceptability of the cookies while the binary effect of soybean and nami flour is significant at p<0.05. Quadratic effect of soybean and nami flour has a positive effect on its texture acceptability which means that texture of the product can be improved if soybean and nami formulation. Oilness is combined in the The cookies produced were described as not oily to slightly oily. Mean oiliness acceptability of the cookies varies from 7.28 to 7.90 with an overall mean acceptability of 7.58 (Table 4). Combinations with high level of soybean flour were perceived by the panelists as slightly oily. Results show that oiliness acceptability of the cookies was affected by varying levels of all- purpose, soybean and nami flour. Acceptance rating increases as amount of all- purpose and nami as a main ingredient increases. On the other hand, acceptance rating falls gradually as the amount of soybean increases. Analysis of variance (Table 2 ) indicates that oiliness acceptability is found to be significantly fit to the linear model (p<0.01) of the response. Parameter estimates as shown in Table 3 reflect that cookies with different combinations of flour as a main component in the mixture has no significant effect on the oiliness acceptability of the cookies which means that any combination of the three different types of flour that will be incorporated in the cookie formulation will not result to a big difference in the oiliness acceptability. General Acceptability General acceptability of the product is a sensory rating on how the panelists or possible consumer feel or like the overall quality of a food product. General acceptability of the treatments ranged from 6.85 to 8.00 or like slightly to like very much (Table 4). It has an overall mean acceptability rating of 7.51 which falls to like moderately. Data show that the acceptance rating increases, as the amount of all- purpose flour increases regardless of the other two variable and decreases, as the amount of nami and soybean increases (Figure 2). The general acceptability is found to be significantly fit to the linear and quadratic model (p<0.01) of the soybean and nami response (Table 2). Parameter estimates (Table 3) reflect that mixtures with only one type of flour as its main component has a highly significant effect on the general acceptability of the cookies as well as the mixture with combination of soybean and nami 76

9 Figure 2. Ternary graph of the general acceptability of the cookie product as affected by different levels of all- purpose, soybean and nami flour flour. Quadratic effect of soybean and nami flour has a positive effect on its general acceptability rating. If more nami and soybean flour will be incorporated in the mixture, its general acceptability tends to decrease. However, if at least two types of flour are used in the mixture, general acceptability increased or improved as implicated in Table 3. Since most of the sensory attributes of the product were highly affected by nami and soybean flour, it also results to positive effect on its general acceptability. Cost Analysis The cost in the manufacturing of the formulated cookies ranges from Php 5.90 to Php 7.29 with an overall production cost of Php 6.37 for every 30 grams of the product (Table 5). Cookie composed of high level of soybean flour turned to be more expensive than those with only nami and all- purpose flour as its components. Raw soybeans are already expensive upon buying it in the market. Optimization of the Formulation Formulation is assumed to be at optimum if it lies within the range of the consumers acceptability in relation to its sensory attributes and production cost. Contour plots generated were superimposed to attain a region that includes high acceptability at a very acceptable price. Mean acceptability rating of 7.5 and was used as a basis for cutoff for every sensory attribute and a maximum production cost of Php 6.20 as a cut-off basis for processing cost to draw possible consumers since they tend to purchase products having high quality at low price. The area being shaded in Figure 2 illustrates the optimum region that can be used in processing cookies that will likely satisfy the sensory taste and budget of the possible consumers. Its limiting factors were the cost, color and aroma. The point in which the aroma and cost intersects was considered the optimum point having a formulation of 25.89% w/w all-purpose flour, 31.25% w/w soybean flour and 42.86% w/w nami flour. Thus, this 77

10 Table 5. Summary of cost production of formulated cookies Treatments All-Purpose Flour (%w/w) All-Purpose Flour (%w/w) Nami Flour (%w/w) Cost/ Pack (Php) Figure 3. Superimposed ternary graph of the sensory acceptability of the cookies formulated with varying amount of all-purpose, soybean and nami flour at an acceptability rate 7.5 of the 9-point Hedonic scale formulation was subjected to verification test and consumer test. Verification Verification study shows that the predicted and observed sensory acceptability of optimum region formulation except aroma were not significantly different from each other. This result implies that there is predictive ability of the models generated on all of the sensory attributes except aroma. Model equation for the aroma of the optimum had underestimated the aroma acceptability of the product that the actual acceptability was significantly higher than the predicted value. One reason to this is that sensory evaluation is subjective thus, it cannot be assured that the panelists were very accurate in giving their response or their choice of acceptability rating on the product. Another is that aroma, is one of the limiting 78

11 Table 6. T-test results from verification test for comparing predicted and observed sensory acceptability of the optimum treatment (25.89% all- purpose flour, 31.25% soybean flour and 42.86% nami flour) Parameter Predicted Observed T-Value Color ns Texture ns Taste ns Oiliness ns Aroma ** Flavor ns General Acceptability ns N=30, **highly significant at ρ<%0.01, *significant at ρ<0.05, ns not significant Table 7. Results of chi-square (χ 2 ) analysis between the commercial and optimum product factors of the optimum region thus, and may have caused the significant difference of the predicted and observed value. Consumer Preference Test Target consumers who were, elementary, high school, college and adults/professionals were requested to give their impression and preference between the optimum formulated cookies(25.89% w/w all-purpose flour, 31.25% w/w soybean flour and 42.86% w/w nami flour) and commercial cookies. Among the 100 random respondents evaluated, 85% and 15% of the respondents like and dislike the commercial product, respectively and 78% and 22% of the same respondents like and dislike the optimum formulated cookies, respectively. Preference test shows that 50% preferred the commercial cookie product while the remaining 50% preferred the optimum formulated cookie product. Among the four groups of panelist, the professional workers gave the highest percentage of preference for the optimum formulation of soybean-nami cookies. Although cookies were mostly preferred by children, professional workers had the knowledge of the beneficial effect of the product, thus, they preferred the optimum product. Statistical analysis shows that there is no significant difference in the preference between the commercial and the optimum cookie product. This suggests that the cookies made from soybean and nami flour can compete with the commercial cookie at the market (Table 7). Proximate Analysis Results revealed that optimum combination (25.89% w/w all- purpose flour, 31.25% w/w soybean flour and 42.86% w/w nami flour) of the three different types of flour has 5.90% moisture content, dry matter of 94.11%, ash of 1.08%, 8.47% of protein, 19.83% fat and 0.27% fiber. The high protein content of the optimum formulated cookie product is attributed by the incorporation of egg and soybean in the product. Inclusion of margarine and lard in the cookie formulation contributed to the high amount of fat in the product. 79

12 Conclusion Therefore, the results imply that there is a possibility that a cookie product can be formulated from nami together with varying levels of all- purpose and soybean flour to improve its nutritional function considering the nutrients in the raw materials used. The optimum formulation has a level of 25.89% w/w all- purpose flour, 31.25% w/w soybean flour and 42.86% w/w nami flour at the cost of Php 6.20 / 30 grams and an acceptability rating of 7.5 corresponding to like moderately of the 9-point Hedonic scale. Recommendation With the obtained results, it is highly recommended to analyze the proximate composition of the commercial counterpart cookie product to compare with the optimum formulation. The physico-chemical property of the product should be evaluated. The functional property and shelf-life of the product should also be determined. Product profiling is also recommended using a trained panel. References Cited Aprianita, A., Purwandari, U., Watson, B. and Vasiljevic, T. (2009). Physico- chemical properties of flours and starches from selected commercial tubers available in Australia. International Food Research Journal,16, Barton, R.R. (2016). Encyclopedia of operations research and management science. Response Surface Methodology. Pp Cochran, G.M. and Cox, W.G.(1980). Experimental designs, 2nd Edition. New York: John Wiley and Sons, Inc. Fanzo, J. (2010). Nutrition and consumer protection. Retrieved from FAO: en.stm/ Accessed January, 2016 Giovanni, M. (1983). Response surface methodology and product optimization. Food Technology, 28(3). Harborne, J.B. (1973). Phytochemical methods: A guide to modern techniques of plant analysis. London: Chapman and Hall Koyabashi,A., Tsuda,Y., Hirata,N., Kubota,K., & Kitamura, K. (1995). Journal of Aroma Constituents of Soybea (Glycine max (L.) Merril) Milk Lacking Lipoxygenase Isoenzymes, 43(9), Kubota, K. (2007). Role of aroma on the palatability of food. Foods and Food Ingredients Journal of Japan, 212(11). Liu, Q., Donner, E., Yin, Y., Huang R.L. & Fan, M.Z. (2006). The physicochemical properties and in vitro digestibility of selected cereals, tubers and legumes in China. Food Chemistry, 99, Mabesa, L.B Sensory evaluation of foods: Principles and methods. College of Agriculture, University of the Philippines,Los Banos,College, Laguna. Messina, M. J. (1999). Legumes and soybeans: overview of their nutritional profiles and health effects 1,2. The American Journal of Clinical Nutrition,70(3 Suppl), 439s-450s. Messina,M.J. (2003). Emerging evidence on the role of soy in reducing prostate cancer risk. Nutrition Reviews, 61(4), Michaelides, D. J. (2009). Technical talk: Wheat flour fundamentals. Bakers Journal. 80

13 Myers,R.H., D.C. Montgomery & Cook, C. (2009). Response surface methodology: Process and optimization using designed experiments. Ogden, R. B. (2003). Children s eating attitudes and behaviour: a study of the modelling and control theories of parental influence. Oxford Journals Health Education Research. Rekha, M. A. (2002). Alpha-amylase inhibitor changes during processing of sweet potato and taro tubers. Plant Food For Human Nutrition, 52, Sasiwatpaisit, N., Thitikornpong, W., Palanuvej, C., & Ruangrungsi, N. (2014). Dioscorine Content in Dioscorea hispida Dried Tubers in Thailand by TLC-densitometry and TLC Image Analysis. Journal of Chemical and Pharmaceutical Research, 6(4): Shurtleff, W. (2002). Soy fact sheets. Soyfood Association of North America. Retrieved from Accessed on December, 2015 Udensi, E.A., Oselebe, H.O. & Eweala, O.O. (2008).The investigation of chemical composition and functional properties of water yam (textitdioscorea alata): Effect of varietal differences. Pakistan Journal of Nutrition, 7(2),