Chenopodium Formosanum Koidz.) Flour

Journal of Agricultural Science; Vol. 7, No. 6; 2015 ISSN 1916-9752 E-ISSN 1916-9760 Published by Canadian Center of Science and Education Rheological Properties of Dough and Quality of Salted Noodles Supplemented with Djulis (Chenopodium formosanum Koidz.) Flour 1 1 1 1 2 Po-Hsien Li , Wen-Chien Lu , Chang-Wei Hsieh , Tai-Chen Li & Da-Wei Huang 1 Department of Medicinal Botanical and Health Applications, Da-Yeh University, Changhua, Taiwan 2 Department of Food & Beverage Management, China University of Science and Technology, Taipei City, Taiwan Correspondence: Po-Hsien Li, Department of Medicinal Botanical and Health Applications, Da-Yeh University, No.168, University Rd., Dacun, Changhua 51591, Taiwan. Tel: 886-4-851-1655 ext. 6233. E-mail: [email protected] Received: March 11, 2015 Accepted: April 12, 2015 Online Published: May 15, 2015 doi:10.5539/jas.v7n6p84 URL: http://dx.doi.org/10.5539/jas.v7n6p84 Abstract Djulis (Chenopodium formosanum Koidz.) has attracted attention worldwide for its nutritional value and health benefit. To examine the potential application of djulis flour in oriental starch-based staple products, we supplemented wheat flour with djulis flour in different proportions to investigate the rheological properties of dough and determine the sensory and textural profile of salted noodles. For dough characteristics measured by farinography and extensography, increased amount of djulis flour decreased the departure time, stability, arrival time and extensibility of dough, but increased the maximum resistance to extension. The cooking loss and hardness of salted noodles increased with increased amount of djulis flour. However, the overall sensory acceptability did not differ between salted noodles with djulis flour and controls (p < 0.05). In conclusion, djulis flour could be proportional incorporated into wheat flour and have a positive influence on salted noodle sensory quality. Keywords: djulis, salted noodle, dough characteristics, sensory quality 1. Introduction Djulis (Chenopodium formosanum Koidz.), belonging to the Chenopodium genus, is an annual crop plant traditionally used by the people worldwide. Djulis grains are edible, commonly served as fermented materials in the process of making liquor, and possess highly nutritional and functional components such as essential amino acids, dietary fiber, betanin, daidzein and genistein (Tsai et al., 2010; Lutz et al., 2013). The well-recognized nutritive value allowed this genus plant to be included in the NASA list of candidate crops for life support in outer space (Schlick & Bubenheim, 1996). Djulis contains a natural antioxidant betanin and has shown ferric reducing ability of plasma and DPPH scavenging capacity (Tsai et al., 2010). Feeding animals with djulis grain nanoparticles reduced plasma low-density lipoprotein cholesterol and total cholesterol levels (Tsai et al., 2011). This crop plant has ethnobotany value; however, the application of the crop to food has received little study. There is a new tendency to incorporate high-volume fractions of plant materials to the basic ingredients of wheat flour (De Oliveira et al., 2006; Koh et al., 2011; Li et al., 2012; Choy et al., 2013). Such incorporated ingredients can provide different flavors, colors, additional nutrients and, often, health benefits. However, these incorporations have significant effects on the physicochemical properties of the dough (Silva et al., 2013) and sensory properties of products (Han et al., 2013). The addition of legume flours to durum wheat flour causes deteriorated cooking quality and textural properties of these products (Petitot et al., 2010). Noodles prepared with 20% buckwheat flour showed increased antioxidant rutin content and enhanced quality of instant noodles (Choy et al., 2013). Salted noodles based on blends of wheat flour and 5% to 15% purple yam flour show increased water adsorption and decreased dough stability on farinography, and the purple yam enrichment conferred redness to the salted noodles as a pleasant purple-red color for consumers (Li et al., 2012). Noodle products are the wheat flour-based staple food in many parts of Asia; they have been consumed for thousands of years. Traditional salted noodles are made from common ingredients (wheat flour, water and salt), 84 www.ccsenet.org/jas Journal of Agricultural Science Vol. 7, No. 6; 2015 and although claimed to be rich in carbohydrate, they lacks other essential nutritional components, which are removed during wheat flour refinement (Choo & Azin, 2010). Nowadays, foods with high nutritional value and functional properties of supplements are popular. In this study, we aimed to investigate the physical and sensory properties of salted noodles with wheat flour partly superseded by djulis flour. The rheological properties of dough with wheat flour and djulis flour blends were investigated by farinography and extensography. 2. Materials and Methods 2.1 Wheat Flour Wheat flour was provided by Chi-Fa Enterprise Co. (Taichung, Taiwan), which was composed of hard red spring wheat and hard red winter wheat in a 2:3 ratio. The moisture, crude protein, and ash content of wheat flour were 13.52%, 11.74%, and 0.35%, respectively. 2.2 Djulis Flour Djulis (Chenopodium formosanum Koidz.) (Figure 1) was cultivated on November 2013 at a local farm (Pingtung, Taiwan). Djulis grains were separated, sieved, washed and then dried by a vacuum-freeze drier. The dried djulis grains were blended by use of a domestic blender and passed through a 100-mesh (150 μm) sieve. The djulis flour was collected and stored in a freezer with a double-bagged polyethylene. The moisture, crude protein, and ash content of djulis flour were 9.45%, 8.43%, and 0.25%, respectively. Figure 1. Appearance of djulis (Chenopodium formosanum Koidz.) 2.3 Preparation of Blended Samples Djulis flour were blended individually with wheat flour at ratios of 0/100 (djulis flour/wheat flour), 5/95, 10/90, 15/85, and 20/80. Mixing was on a weight (w/w) basis, as described by Zaidul et al. (2007). 2.4 Dough Characteristics The rheological characteristics of dough prepared from control wheat flour and mixtures of wheat flour and djulis flour were determined by farinograph (E-380, Brabender OHG, Germany) according to AACC (2000) standard method. Dough strength was evaluated in terms of farinograph water absorption, dough development time, departure time, dough stability, arrival time and mixing tolerance index were recorded manually. The thermostate of the farinograph was adjusted to maintain the temperature at 30 oC. For extension tests dough was prepared using the farniograph. The extension tests were conducted in accordance with the standard procedure, using the extensograph (Brabender OHG, Germany). The following indices were determined: extensibility and resistance to extension. Measurements of the above farinograph and extensograph 85 www.ccsenet.org/jas Journal of Agricultural Science Vol. 7, No. 6; 2015 indices were made in four replications. 2.5 Preparation of Salted Noodles Salted noodles were prepared as previously described (Li et al., 2012) and with modification. The wheat flour was supplemented with different proportions of djulis flour and blended thoroughly, and then 300 g of each mixture was mixed 102 mL of distilled water (25 oC) containing 6 g of salt at 10 rpm for 8 min to form dough. Dough was passed through the rollers of a noodle machine (Ohtake Noodle Machine Mfg. Co., Tokyo, Japan) at 8 rpm and a 3 mm gap. Folding and sheeting were repeated twice more. The dough sheet was allowed to rest for 30 min, and then was put through the sheeting rolls 3 times at progressively decreasing roll gaps of 2.60, 2.33, and 2.00 mm, and then, the dough sheets were cut into noodle strips of 3 mm in width. Finally, the noodle strips were cut in lengths of 20 cm and air dried at room temperature. Dried noodles were stored in sealed polyethylene bags for further measurements. 2.6 Optimal Cooking Time The optimal cooking time for each sample was determined by using the AACC Method 66-50 (AACC, 2000). It was evaluated by observing the time of disappearance of the white core of the noodle strands during cooking (every 15 s), by squeezing the noodle strands between 2 transparent glass slides. 2.7 Water Absorption Dry noodles (10 g) were boiled in 300 mL boiling water until the white core inside the noodles disappeared, placed in cool water for 5 min, then placed on filter paper for 5 min to remove excess water. Water absorption of the noodles was calculated by the following equation: MM(1 W ) Water absorption (%) = 12 100 (1) MW2 (1 ) Where, M1 is the weight of noodles after cooking (g); M2 is the weight of noodles before cooking (g); and W is the moisture content of noodles before cooking (%). 2.8 Cooking Loss Cooking loss was measured according to the AACC Method 66-50 (AACC, 2000). Cooking water was evaporated and dried at 105 oC to a constant weight. Cooking loss was expressed as a percentage of dry matter lost during cooking to dry sample weight. M Cooking loss (%) = 100 (2) GW(1 ) Where, M is the weight of dry matter (g); G is the weight of noodles before cooking; and W is the moisture content of noodles before cooking (%). 2.9 Color Measurements The color of the salted noodles with different proportions of djulis flour was measured with use of a colorimeter (SE2000, Nippon Denshoku Co., Japan) equipped with D65 illuminant, using the CIE 1976 L*, a* and b* color scale. L* was a measurement of brightness (0-100), a* represents the red-green coordinates while b* measures the blue-yellow coordinates of a product. A piece of the cooked noodle sheets was placed in the sample holder and the surface color was measured at 3 different positions. 2.10 Texture Profile Analysis The hardness, cohesiveness, springiness, gumminess, and chewiness of the cooked salted noodles were tested by the texture profile analysis (TPA) with a texture analyzer (TA-XT2, Stable Micro Systems, UK).

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