Effect of Tomato Seed Meal on Wheat Pasting Properties and Alkaline Noodle Qualities

Transcription

1 Effect of Tomato Seed Meal on Wheat Pasting Properties and Alkaline Noodle Qualities Kamontip Ekthamasut School of Science, University of the Thai Chamber of Commerce Bangkok, Thailand Abstract Experiments were conducted using deoiled tomato seed meal (DTSM) containing 42.48% protein, 42.60% fiber and 2.76% lysine. The pasting properties of wheat flour supplemented with DTSM at 0, 5 and 10% were evaluated using Rapid Visco Analyser (RVA). Substitution of wheat flour with DTSM resulted in a decrease in the viscosity and peak time. In addition, the result also revealed that noodles replaced wheat flour with DTSM had higher cooking weight, protein, fiber, and lysine content but lower cutting force, L* color and sensory quality than the control (p<0.05). Keywords: Tomato seed meal, pasting properties, alkaline noodle Introduction There is an increasing demand in engineering food process wastes to reduce their pollution effects and to increase their value by conversion into useful by-products. Tomato processing wastes, or pomace, have been used in animal feeds and as fertilizer (Al- Betawi, 2005; Persia et al., 2003). Elloitt et al. (1981) demonstrated that tomato pomace is good source of protein and fiber. Seeds, the major part of pomace, contain % protein, % fat, % ash and 35.1% total dietary fiber (Carlson et al., 1981; Latlief and Knorr, 1983; Liadakis et al., 1995; Liadakis et al., 1998; Sogi et al., 2002; Persia et al., 2003). Geisman (1981) noted that tomato seeds lacked antinutritional factors which are often present in other unconventional protein sources. The seed protein is rich in lysine and can supplement products that are deficient in this amino acid like cereals (Tsatsaronis and Boskou 1975; Carlson et al., 1981; Latlief and Knorr 1983; Liadakis et al., 1995). Carlson et al. (1981), for example, showed that the addition of tomato seed to wheat flour bread had a positive effect on loaf volume and improved the overall protein quality of the bread. The supplementation at 10 and 20% replacement levels increased lysine by 40.2 and 69.0% respectively. Sogi et al. (2002) reported that substitution of wheat flour with deoiled tomato seed meal (DTSM) effected on rheological properties by increasing in water absorption, dough stability using Farinograph, but decreasing in peak viscosity and setback on cooling using Viscoamylograph. The bread supplemented with 10% DTSM exhibited good sensory characteristics and improved protein quality. Noodles are popular foods in Southeast Asia and have been become increasingly popular in many countries outside of Asia. Asian noodles can be divided into two general classes: white salted and yellow alkaline (Hou and Kruk 1998). The high ph has many important roles in alkaline noodles. Several of these roles include developing the characteristic yellow color, controlling microbial growth, developing aroma and flavor, modifying dough, and improving noodle texture (Morris et al., 2000). The texture of cooked alkaline noodles should be firm and elastic (or springy) with a smooth surface. Starch pasting properties and the quantitative and qualitative aspects of protein are important for noodle qualities. While higher flour protein content and high protein quality have been associated with firmer bite and more elastic texture (Miskelly and Moss 147

2 1985; Huang and Morrison 1988), protein content has been negatively related to both noodle surface smoothness and color of alkaline noodles (Miskelly and Moss 1985; Moss et al., 1987). The objectives of this research were to determine the effect of tomato seed meal on wheat pasting properties and test its possible utilization in alkaline noodles in order to improve the nutritional quality of noodles. Materials Materials and Methods Tomatoes (Lycopersicon esculentum Mill, cv. Sida Thip ) were purchased from a local market. The seeds were spooned out and sedimented in water, then dehydrated at 70 C for 5 hours in a tray dryer. Seeds were ground using a grinder (Model T71, Moulinex, France) and passed through 25 mesh sieve, extracted oil with hexane (Carllo, Carlo Erba Reagent, Italy), desolventized by drying at 70 C for 1 hour in hot air oven and ground again to obtain fine powder termed as de-oiled tomato seed meal (DTSM). Chemical composition The proximate composition of DTSM and noodles was measured according to standard methods (AOAC 1990). Lysine was determined by the AccQTag method after acid hydrolysis with hydrochloric acid. Pasting Properties Pasting properties of the wheat flour supplemented with DTSM were studied at 0, 5 and 10% replacement levels using the Rapid Visco Analyzer (RVA) (model Super 3, Newport Scientific Pty. Ltd., Australia) according to the procedure described by Noda et al. (2001). Sample (3 g) was added to distilled water (25 ml) and placed in the RVA. The suspension was kept at 50 C for 1 minute, heated to 95 C at 13.2 /minute, kept at 95 C for 2.7 minutes, then cooled to 50 C at 11.6 C/min and kept at 50 C for 2 minute. The RVA experiments were performed in five replicates. Preparation of yellow alkaline noodles Wheat flour or wheat flour substituted with DTSM (100 g) was premixed at low speed on food mixer (Model ECOS 25/30, Sottoriva, Italy) for 1 minute. A solution containing 1 g NaCl, 1.5 g Na 2 CO 3 and 45 g distilled water was added to the flour over a 30 second time period. Mixing continued at medium speed for 5 minute. Dough was folded and passed through the rools of noodle machine (Marcato, Marcato S.p.A., Italy) three times at a gap size of 5 mm. The dough sheet was rested for 30 minutes at room temperature, then reduced six times to a thickness of 1.2 mm and slitted through a no. 12 noodle slitter (2.5 mm width). Noodle were put into polypropylene bags and stored at 4 C for 24 hour until being cooked. Before cooking the noodles were allowed to rest at room temperature (30 C) for 1 hour. Noodle Quality Evaluation Noodles (10 g) were cooked in 150 ml of boiling distilled water for 1 minute and 30 seconds and rinsed with cold water. Cooking loss of noodles (%) was calculated as described by Baik and Lee (2003): Cooking loss = (residue in cooking water [g]/noodle weight before cooking [g]) x 100. Cooked weight of noodles was determined as: Cooked weight = (cooked noodle weight gain [g]/ noodle weight before cooking [g]) x 100. The cutting force of noodles was analyzed with Lloyd Texture Analyzer Model LRX (Lloyd instrument, Hampshire, UK) after cooking within 5 minutes. A set of five strands of cooked noodles was placed parallel on platform and cut crosswise using a 60 cutting-test cell at a speed of 250 mm/minute. The maximum force required to break noodles was recorded as cutting force. Color of both raw and cooked noodles was determined using Hunterlab digital color difference meter Model D25M. L*, a* and b* values denote lightness, rednessgreenness, and yellowness-blueness, respectively. All tests were done in three replicates. 148

3 Sensory evaluation of the cooked noodles was conducted using 5 point scoring test. The sensory panel consisted of ten trained people. Samples were cooked as described above, then evaluated for color, taste, odor, bite, springiness, smooth texture and overall acceptability. Statistical Analysis All tests, except sensory analysis, were run in a completely ramdomized design. A ramdomized block design was applied to the sensory evaluation with the panelist as a blocking factor. SPSS 13.0 for Windows TM (SPSS Inc., Chicago, Ill., USA) was used for statistical analysis. Differences between samples in each item were tested using General Linear Model and Duncan as a post-hoc test. A significance level of p<0.05 was used throughout the study. Results and Discussion Chemical Composition Chemical composition of DTSM is shown in Table 1. The DTSM evaluated in this study was found to contain 42.48% crude protein and 42.60% dietary fiber, which were higher than previous report (Sogi et al., 2002). The differences in this value could be due to different tomato cultivars and processing method. Moreover, DTSM is rich in lysine (2.76%), whereas, wheat flour is deficient in this essential amino acid. Therefore the replacement of wheat flour with DTSM would improve the nutritional quality of noodles. Table 1. Chemical composition of DTSM Component Moisture Ash Crude fat Crude protein Total dietary fiber Available carbohydrate Lysine %wet weight 0.33± ± ± ± ± ± ±0.50 Pasting Properties Pasting properties are dependent on the rigidity of starch granules which in turn affect the granule swelling potential and the amount of amylose leaching out in the solution (Bhattacharya et al., 1999). When an aqueous suspension of starch is heated above a critical temperature, granules swell irreversibly and amylose leaches out into the aqueous phase, resulting in increased viscosity (pasting). At this stage the granules are highly susceptible to thermal or mechanical breakdown because of soluble starch molecules orienting themselves in the stir direction of the system and break up of starch granules, which leads to a decrease in starch paste viscosity. Upon cooling, the starch paste forms a gel (gelification) along with increased viscosity because of energy in the system and subsequent hydrogen bond formation between starch chains (setback) (Brennan et al., 2004). Substitution of wheat flour with DTSM resulted in a decrease in the peak viscosity, breakdown, final viscosity, setback and peak time but an increase in pasting temperature (Table 2). They were independent of the level of DTSM substitution because of form a reduction in starch content and an increase in protein and fiber content of the pastes when replaced with DTSM. The apparent amylose content of flour correlates significantly with peak viscosity, final viscosity, breakdown and setback in RVA (Zeng et al., 1997; Yamamori and Quynh, 2000). Symon and Brennan (2004) reported that substitution of 5% wheat starch with β-glucan-rich fiber fractions from barley decreased the peak viscosity, breakdown and final viscosity in comparison to the control starch (p<0.05). This reduction is likely to be because of water being withheld from the starch granules by the β-glucan and a decrease in the starch content of wheat flour pastes. Sogi et al. (2002) reported on pasting properties of wheat flour blended with DTSM at 0-30% using Brabender viscoamylograph indicated that peak viscosity, viscosity at 95 C, viscosity at 50 C and setback on cooling decreased with the increase in levels of DTSM. Breakdown is a measure of susceptibility of cooked starch granules to disintegration, 149

4 whereas setback is a measure of recrystallization of gelatinized starch during cooling (Beta and Corke 2001). A low breakdown of wheat flour blends suggests that they are more stable under hot conditions than wheat flour. Moreover, wheat flour blends exhibit lower setback value indicating less amylose retrogradation as the system is cooled. In addition, the difference in pasting properties of wheat flour and wheat flour blends also could be due to other factors, such as particle size, enzyme activity or water-holding capacity. Noodle Qualities Physical properties of yellow alkaline noodles made from wheat flour and wheat flour blends are evaluated in Table 3. No significant difference was observed in cooking loss of noodles (p>0.05), while cooked weight increased and cutting force decreased with increasing in levels of DTSM substitution (p<0.05). The greater cooked weight of noodles prepared from wheat flour replaced with DTSM was probably due to the higher protein and fiber content, the higher water-holding capacity. As expected, noodles caught greatly water and became softer texture and low cutting force. DTSM strongly affected color of both raw and cooked noodles. As the amount of DTSM was increased from 0 to 10%, color became significantly darker, indicated by decreasing L* values. The dark color was associated with polyphenol oxidase activity (Park et al., 1997). The higher amounts of DTSM seemed to provide additional enzyme and substrate. Moreover, there was significantly higher yellowness and redness intensity by increasing DTSM replacement, indicated by increasing b* and a* values, respectively. These results are in accordance with those of Mohamed et al (2005) who reported that the yellow color of noodles became darker with higher Nutrium (the soluble fiber in a layer between seed cover cells of oats) amounts added. Eating quality scores of noodles indicated a significant decrease in color, taste, odor, smooth texture and overall acceptability with the incorporation of DTSM, while there were no significant difference in bite and springiness (Table 4). The color score was low because of darkness as a result of the color by HunterLab (Table 3). The taste and odor were affected due to a characteristic flavor contributed by DTSM (Sogi et al., 2002). The smooth texture was affected by the higher particle size of DTSM than that of wheat flour. The color, taste and odor of noodles prepared from 10%DTSM supplementation were significantly lower than that of 5% DTSM supplementation (p<0.05), but were not significantly different in smooth texture and overall acceptability (p>0.05). This result indicated that the panelists could accept the noodles prepared from wheat flour blends in the middle level (score = ). However, the panelist cannot detect the difference of control and wheat flour blend noodles when they were cooked with seasoning (data not show). The results of the addition of DTSM to wheat flour on noodles at varying replacement Table 3. Effect of DTSM supplementation on physical properties of noodles DTSM supplementation 0% 5% 10% Color d Raw Cooked L* a* b* L* a* b* a 0.79 c 4.03 c a c 3.97 c b 3.25 b 4.73 b b 2.52 b 4.57 b b 3.37 a 5.42 a c 3.03 a 4.92 a Cooked weight (%) b b a Cooking loss (%) 4.01 a 4.25 a 5.23 a Cutting force (N) 2.79 a 2.53 b 2.25 c a, b, c d Means in the same column with different superscripts are different (p<0.05) Color: L* = lightness (0 = black, 100 = white) a* = redness/greenness (+ = red, - = green) b* = yellowness/blueness (+ = yellow, - = blue) 150

5 Table 4. Effect of DTSM supplementation on eating qualities of noodles DTSM supplementation Color Taste Odor Bite Springiness Smooth texture Overall acceptability 0% 4.5 a 4.2 a 4.1 a 3.3 a 3.8 a 4.1 a 4.1 a 5% 2.1 b 3.2 b 3.2 b 3.4 a 3.2 a 3.1 b 2.8 b 10% 1.3 c 2.7 c 2.7 c 3.2 a 3.3 a 2.6 b 2.4 b a, b, c Means in the same column with different superscripts are different (p<0.05) levels are given in Table 5. Increasing substitution of DTSM resulted in an increase in protein and fiber up to 24 and 155% respectively. These data indicated an increase in the chemical score for lysine in wheat flour noodles of 100% at the 10% replacement levels. Table 5. Chemical composition of noodles prepared form wheat flour supplemented with 10% DTSM Component (% wet weight)) Moisture Ash Crude fat Crude protein Total dietary fiber Available carbohydrate Lysine a, b Control 31.04±0.23 b 1.99±0.28 a 1.02±0.20 a 9.63±0.11 b 2.00±0.43 b 54.32±0.35 a 0.21±0.11 b 10% DTSM 32.55±0.13 a 2.02±0.04 a 1.14±0.29 a 11.94±0.25 a 5.10±0.65 a 47.25±0.54 b 0.42±0.22 a Means in the same row with different superscripts are different (p<0.05) Conclusion It may be concluded that supplementation of wheat flour with DTSM (up to 10%) in yellow alkaline noodles improved the protein, fiber and lysine content; however, physical and eating qualities were affected. As the proportion of DTSM increased from 0 to 10% in wheat flour blends, there were decreases in peak viscosity from to RVU and increases in pasting temperature from to C. References Al-Betawi, N.A Preliminary study on tomato pomace as unusual feedstuff broiler diets. Pakistan J. Nutr. 4: AOAC Official method of analysis. 15 th ed. Association of Official Analytical Chemists. Arlington, Virginia. Baik, B.K.; and Lee, M.R Effect of starch amylose content of wheat on textural properties of white salted noodles. Cereal Chem. 80: Beta, T.; and Corke, H Noodle quality as related to sorghum starch properties. Cereal Chem. 78: Bhattacharya, M.; Zee, S.Y.; and Corke, H Physicochemical properties related to quality of rice noodles. Cereal Chem. 76: Brennan, C.S.; Tan, C.K.; Kuri, V.; and Tudorica, C.M The pasting behaviour and freeze-thaw stability of native starch and native starch-xanthan gum pastes. Int. J. Food Sci. Tech. 39: Carlson, B.L.; Knorr, D., and Watkins, T.R Influence of tomato seed addition on the quality of wheat flour breads. J. Food Sci. 46: , Elloitt, J.; Mulvihill, E.; Dumcan, C.; Forsythe, R.; and Kritchevsky, D Effect of tomato pomace and mixed vegetable pomace on serum and liver cholesterol in rats. J. Nutr. 111:

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