The relationship between chinese raw dumpling quality and flour characteristics of shandong winter wheat cultivars

Agricultural Sciences in China 2011, 10(11): 1792-1800 November 2011 © 2011, CAAS. All rights reserved. Published by Elsevier Ltd. doi:10.1016/S1671-2927(11)60179-X The Relationship Between Chinese Raw Dumpling Quality and Flour Characteristics of Shandong Winter Wheat Cultivars ZHANG Yan 1, 2 , YE Yi-li 2 , LIU Jian-jun 3 , XIAO Yong-gui 2 , SUN Qi-xin 1 and HE Zhong-hu 2, 4 1 College of Agriculture and Biotechnology, China Agricultural University, Beijing 100193, P.R.China 2 Institute of Crop Science/National Wheat Improvement Center, Chinese Academy of Agricultural Sciences, Beijing 100081, P.R.China 3 Crop Research Institute, Shandong Academy of Agricultural Science, Jinan 250100, P.R.China 4 CIMMYT China Office/Chinese Academy of Agricultural Sciences, Beijing 100081, P.R.China Abstract Dumpling is one of the most important traditional wheat products in China. Dumpling quality is determined by the characteristics of both flour and filling, thus improvement of flour quality plays an important role in improving dumpling quality. Thirty-nine Shandong winter wheat cultivars and advanced lines sown in Jinan, Shandong Province, China, in the 2008-2009 cropping season were used to determine genetic variation in Chinese raw dumpling quality and its relationship with flour characteristics. Large variations were observed for protein quality parameters in comparison with starch properties. Variation in color of the raw dumpling sheet was broader than that of sensory evaluation parameters of boiled dumpling among tested wheat cultivars, indicating the large influence of filling on dumpling color. Two cultivars, Jimai 20 and Zimai 12, were identified as possessing very good quality of raw dumpling, and 21 cultivars and advanced lines showed good quality. Protein and total starch content influenced the L * value of raw dumpling sheets. L * value at 0 and 2 h after sheeting were significantly influenced by protein content (r=-0.46 and -0.52, P<0.01) and total starch content (r=0.55 and 0.57, P<0.01), respectively. Flour yellow pigment was significantly corrected with a * (r=-0.67 and -0.62, P<0.01) and b * (r =0.87 and 0.84, P<0.01) value of raw dumpling sheets at 0 and 2 h after sheeting, respectively. Gluten strength parameters such as farinograph mixing tolerance index (MTI, r=-0.55, P<0.01) were positively associated with appearance. MTI and energy were also significantly and positively correlated with elasticity of raw dumpling, with r=-0.54 and 0.47 (P<0.01). The positive relationships between peak viscosity (r=0.51, P<0.01), breakdown (r=0.54, P<0.01), and smoothness of raw dumpling were also observed. Therefore, it is suggested that breeding programs should give more attention to gluten strength and starch pasting parameters for raw dumpling quality improvement. key words: Triticum aestivum, protein content, gluten strength, starch pasting properties, raw dumpling Received 17 Feburary, 2011 Accepted 30 March, 2011 ZHANG Yan, Associate Professor, Tel: +86-10-82108741, E-mail: zhycaas@yahoo.com.cn; Correspondence HE Zhong-hu, Professor, Tel/Fax: +86-10-82108547, E-mail: zhhecaas@163.com INTRODUCTION Dumpling is one of the most important traditional wheat products in China. Approximately 8% of Chinese wheat is used to manufacture dumpling (Zhang 2007), and its use could have a history of more than 1 000 years (Lou and Yang 2004). It can be served at all three meals daily, but is more frequently consumed at mid-day and in the evening. It is especially important in northern China since dumpling is served as a main dish during Chinese New Year. Two types of dumpling, i.e., raw and frozen styles, are generally recognized. Raw dump- ling is widely consumed because it is considered to The Relationship Between Chinese Raw Dumpling Quality and Flour Characteristics of Shandong Winter Wheat Cultivars 1793 © 2011, CAAS. All rights reserved. Published by Elsevier Ltd. have better texture and flavor than the frozen type. Frozen dumpling is basically marketed in cities and its consumption is rapidly increasing. Dumplings are mainly made from wheat flour dough and fillings such as meat, vegetables, eggs, oil, soybean sauce, salt, and monosodium glutamate. Dumpling quality is determined by both the characteristics of the flour and filling. Therefore, improvement of flour quality plays an im- portant role in improving dumpling quality. Up to now, limited studies have been undertaken to understand the genetic variation of dumpling quality among different genotypes and effects of flour traits on dumpling quality. At the same time, laboratory evalu- ation methods for assessment of dumpling quality still need to be improved. Therefore, genetic improvement of dumpling quality is progressing much more slowly in comparison to white salted noodles and pan bread. Several studies have focused on the relationship be- tween flour traits and frozen dumpling quality (FDQ) (Lou et al. 2004; Zhang et al. 2005 a; Li et al. 2006; Y ang and Sun 2006), and the effects of flour additives on dumpling quality (Wang et al. 1998; Liang et al. 2006; Yang et al. 2006). Farinograph development time and stability, and starch pasting peak viscosity were posi- tively associated with total score of FDQ (Li et al. 2006; Yang and Sun 2006). Lou and Yang (2004) reported that total FDQ score was not significantly associated with flour protein content and dough extensibility, but was significantly and negatively correlated with starch content. However, there is one report that flour water absorption, farinograph development time, stability and extensograph energy positively influence the color of raw dumpling sheet and viscosity of boiled dumpling sheet without filling; they had negative effects on the hardness and elasticity of boiled dumpling sheets, but starch pasting final viscosity and breakdown were posi- tively associated with viscosity and hardness of boiled dumpling sheets (Lan et al. 2010). Therefore, much more efforts are needed to understand the relationship between wheat flour traits and raw dumpling quality so as to help wheat breeding programs to respond to con- sumer and market demands. Dumplings can also be classified by ingredients of filling, i.e., meat or vegetable filling styles (Qi 2000; Tang 2001). Ingredients include meat (pork, beef or mutton), egg, and many kinds of vegetables such as cabbage, turnip, carrot, mushroom, Chinese chives, celery, and other auxiliary materials (e.g., oil, shallot, ginger, salt, and monosodium glutamate). Meat-filled dumplings are made from dough, meat, vegetables, and auxiliary materials, whereas vegetable-filled types are made from dough, eggs, vegetable and auxiliary materials, or without eggs. Although no official data are available, it is generally agreed that Chinese con- sumption of the two styles is about equal. Therefore, vegetable-filled dumpling was chosen for this study. Due to limited land and population pressure, improve- ments in grain yield, disease resistance, and early ma- turity have been the major wheat breeding objectives in China. However, improvements in processing quality, especially for pan bread and noodles, have become important objectives during the last 20 years (Zhang et al. 2007). With rapid improvement of living standards in China, cultivars with high dumpling quality are in ur- gent demand to suit the needs of increased mechanized production. The objectives of this study were to deter- mine the fresh dumpling quality variability present in Chinese winter wheat germplasm and to understand the relationship between flour characteristics and color, appearance, and eating quality of fresh dumpling. MATERIALS AND METHODS Wheat samples Thirty-nine winter wheat genotypes (Table 1) from Shandong Province, China, including leading cultivars from 1990 to the present and advanced lines, were used in this study. Shandong Province is the second largest wheat producer in China, and the cultivars and lines used in this study represent most of the current elite lines for quality improvement in north China. They were grown during the 2008-2009 cropping season at the Crop Research Institute, Shandong Academy of Ag- ricultural Sciences, in Jinan. A randomized complete block design with three replicates was employed. Test plots were managed according to local practices. All samples were free of sprouting damage. Analytical methods Wheat samples collected from the three replicates were 1794 ZHANG Yan et al. © 2011, CAAS. All rights reserved. Published by Elsevier Ltd. mixed and a 5-kg sample of each cultivar was cleaned, and tempered overnight. Hard, medium, and soft wheats were tempered to around 16.5, 15.5, and 14.5% mois- ture content, respectively. All samples were milled on a Buhler MLU 202 laboratory mill (Buhler Bros, Ltd., Uzwil, Switzerland) according to AACC method 26- 21A to give flours with 60% extraction rates. Grain hardness and moisture were determined using the Single Kernel Characterization System (SKCS 4100, Perten Instruments, Sweden). Flour protein content (14% MB) was recorded with a NIR analyzer foss- tecator 1241 (Foss, Högänas, Sweden). Flour color was measured using a Minolta Chromameter CR 310 (Minolta Camera Co., Ltd., Japan) with the CIE 1976 L * , a * , b * color space equipped with a D65 illuminant. L * is brightness measured from 0 (black) to 100 (white), a * is a function of the green to red difference, and b * is a function of the blue to yellow difference. Farinogragh and extensograph parameters were obtained according to AACC approved methods 54-21 and 54-10, respectively. Starch pasting peak viscosity and break- down were obtained using a rapid visco analyzer (RVA- 3D super type, Newport Scientific) as described by Batey et al. (1997). Amylose and starch content were measured according to Kiribuchi-Otobe et al. (1997). Flour yellow pigment was determined according to AACC approved methods 14-15 using a TU-1800PC UV-VIS spectrophotometer (Beijing Purkinje General Instrument Co., Ltd., China). Flour polyphenol oxi- dase (PPO) activity was estimated as described by Anderson and Morris (2001) using the same spectro- photometer as flour yellow pigment. Raw dumpling preparation Based on our previous unpublished data, the optimum water absorption for dumpling production was adjusted to be 41% of flour weight. Dumpling dough was pre- pared by mixing flour (200 g, 14% MB) with enough water to achieve 41% water absorption using a Na- tional pin mixer (USA) for 1 min. After mixing, the dough was kept in a plastic container for 15 min at room temperature before passing through the sheeting rollers of a laboratory noodle machine (Ohtake 150, Tokyo, Japan). Sheeting occurred once with a 4-mm roll gap setting, and then four times at 3-mm roll gap settings including no folding on the third pass. During the sheeting process, a small amount of dry flour was sprinkled onto the sheets to avoid sticking to the rollers. The sheet dough was kept again in a plastic storage container for 15 min at room temperature. Subsequently, the reduction in sheet thickness was achieved by suc- cessive passes through roll gaps of 2.2 and (1.5±0.05) mm. The gap between the rollers for the final pass was determined precisely using a test piece cut from the main sheet after the previous pass. The final sheets were cut into round pieces with a round stainless steel cutter (6 cm diameter) to obtain dumpling sheets. The filling was a blend of ingredients (200 g of mac- erated cabbage, 100 g of fried egg, 10 g of oil, 6 g of shallot, 3 g of ginger, 3 g salt, and 1 g monosodium glutamate) mixed in a plastic container. Fried egg made from equal amounts of egg and oil was used in the vegetable filling to reduce the variation of filling in dif- ferent tests. The dumpling sheets were shaped to con- tain 3 g filling, shaped as a dumpling, and stored in a flat dish at room temperature. Raw dumplings (25 units per sample) were boiled for 5 min in 2 L of boiling water. Four cooking sessions were processed at the same time. After boiling, the dumplings were rinsed in running cold tap water for 1 min. Sensory evaluation was performed with at least five skilled panelists and finished within 10 min. Table 1 Thirty-nine cultivars and advanced lines assessed for raw dumpling quality Cultivar Type Cultivar Type Jimai 19 Cultivar Taishan 223 Cultivar Jimai 20 Cultivar Tainong 18 Cultivar Jimai 22 Cultivar Wennong 6 Cultivar Jimai 5319 Cultivar Weimai 8 Cultivar Jimai 6097 Cultivar Yannong 19 Cultivar Jimai 6487 Cultivar Yannong 23 Cultivar Jimai 7251 Cultivar Yannong 24 Cultivar Jimai 7327-2 Cultivar Zimai 12 Cultivar Jinan 17 Cultivar Zhongmai 155 Line Jining 13 Cultivar BPT08058 Line Jining 16 Cultivar Jimai 035037 Line Linmai 2 Cultivar Jimai 037042 Line Linmai 6 Cultivar Jimai 046402 Line Liangxing 66 Cultivar Jimai 056852 Line Lumai 21 Cultivar Jimai 065504 Line Lumai 23 Cultivar Jimai 066324 Line Shannong 15 Cultivar Jimai 076128 Line Taishan 21 Cultivar Jimai 077019 Line Taishan 23 Cultivar Jimai 077072 Line Taishan 24 Cultivar The Relationship Between Chinese Raw Dumpling Quality and Flour Characteristics of Shandong Winter Wheat Cultivars 1795 © 2011, CAAS. All rights reserved. Published by Elsevier Ltd. Raw dumpling sensory evaluation Although an official method for sensory evaluation of Chinese raw dumpling (SB/T 10138/93) (Chinese Min- istry of Commerce 1993) has been used since 1993, it has been suggested that improvements can be made. The scoring system, including color (weighting factor 10), brightness (10), transparency (10), resilience (15), stickiness (15), smoothness (10), resistance at boiling (15), and soup characters (15), has two problems. Firstly, evaluation of soup characters is not easy; de- grees of clearness or feculence of water after cooking dumpling is estimated by panelists. However, most panelists have difficulties in giving precise or consis- tent scores for soup characteristics. Secondly, firm- ness is not included in the evaluation system. High quality raw dumpling sheets should be characterized with whiteness and brightness for color, softness and resilience, lack of stickiness and smoothness of texture. Because color and firmness are considered to be more important parameters for scoring raw dumpling by the industry, firmness instead of soup characteristics was adopted in a modified scoring system. For appearance of raw dumplings, panelists should assess the degrees of flatness, and lack of gas bubbles and rupturing of dumpling sheets. Flatness requires that the dumpling sheet surface is flat and uniform, has no gas bubbles, and rupture is mainly considered to ensure that the sheets have no cracks after boiling. Resistance at boil- ing is similar to an assessment of appearance, and was therefore replaced by appearance in the modified scor- ing system. Based on the noodle evaluation system described by Zhang et al. (2005b), the modified scor- ing system for dumpling included six parameters, viz., color (20), appearance (20), firmness (20), elasticity (20), stickiness (10), and smoothness (10). Four samples were tested at each panel session including the Chinese commercial flour Xuehuafen as a control. Samples under test were compared with the control and a score was assigned to each parameter. The pan- elists firstly compared color and appearance of boiled dumplings, and then opened the fringe of the dumpling and removed the filling, followed by evaluations of firmness, elasticity, stickiness, and smoothness of boiled dumpling sheets. Color measurements of dumpling sheets Color of raw dumpling sheets was measured with a Minolta Chromameter CR 310 (Minolta Camera Co., Ltd., Japan) with the CIE 1976 L * , a * , b * color space equipped with a D65 illuminant. The sheets were mea- sured on a Royal Australian Cereal Institute (RACI) stan- dard backing tile, with three measurements being made on each side of the dumpling sheet. Raw dumpling sheets were measured after sheeting (0 h), and again after 2 h of storage in a covered plastic container at 25°C. Statistical analysis SAS (Statistics Analysis System, SAS Institute, Cary, NC) was employed to compute means, standard deviations, and correlation coefficients. RESULTS Grain and flour characterization of tested wheat cultivars Means, coefficients of variation (CV), and ranges of grain hardness, protein content, farinograph and extensograph parameters and starch quality parameters including peak viscosity, breakdown, final viscosity, amylose and total starch content for tested wheat culti- vars are presented in Table 2. As expected, large varia- tions were observed for protein quality parameters in comparison with starch traits. The largest variations involved dough development time, stability, MTI, energy, and maximum resistance, with CVs of 40.5, 71.6, 53.4, 53.1, and 57.0%, respectively. Only small variations in amylose and total starch contents were observed, with CVs of only 2.7, and 1.5%, respectively. Variation in raw dumpling quality Broad variations were observed for a * and b * values for raw dumpling sheets at 0 and 2 h, but not for L * values (Table 3). The largest variations for a * values with CVs of 89.1% at 0 h and 52.3% at 2 h, and wide varia- 1796 ZHANG Yan et al. © 2011, CAAS. All rights reserved. Published by Elsevier Ltd. tion for b * values with CVs of 11.3% at 0 h and 11.5% at 2 h occurred with raw dumpling sheets. This indi- cated that variation for color of raw dumpling sheet might mainly come from the variation in a * and b * values, but not in L * values. Yannong 24, Zhongmai 155, Liangxing 66, Jimai 20, and Yannong 23 performed best in color of raw dumpling sheets. They could therefore be used as parents in crossing programs for flour color improvement. On the other hand, Jinan 17, Jimai 7327-2, Jimai 077072, Wennong 6, and Jimai 037042 were iden- tified as having poor raw dumpling sheet color. There were small variations in sensory evaluation parameters of boiled dumplings in comparison with the color of raw dumpling sheets. The range in CV for sensory evaluation parameters of boiled dumpling was 4.9-9.0%. Variation in color of boiled dumplings was significantly smaller than that of raw dumpling sheets. The reason for the discrepancy might be that the dump- ling filling significantly influenc es panelists visual as- sessments of boiled dumpling color, hence reducing the differences in color of boiled dumpling among genotypes. Variations in color, appearance, and firm- ness of boiled dumplings were slightly larger than those for elasticity, stickiness, and smoothness. Chinese commercial flour, Xuehuafen, used as the control in this study is considered to be of good quality for noodles and dumplings. Relative to the assessment score of 70.0 for Xuehuafen in this study, raw dump- ling scores above 75.0 were considered very good, scores of 70.1-75.0 good, scores of 65.0-70.0 fair, and scores below 65.0 were poor (Table 4). Cultivars including Jimai 20 (total score 78.3) and Zimai 12 (76.0) were identified as possessing very good boiled fresh dumpling quality. Jimai 20 was the leading cultivar in the Yellow and Huai Valley, and was characterized with very good white salted noodle quality (Ye et al. 2010). Zimai 12 is also a released cultivar. Twenty-one culti- vars and advanced lines had good fresh dumpling quality. Overall, Chinese winter wheat generally had acceptable quality for boiled fresh dumpling. This out- come could be due to the improvement of pan bread and noodle quality that has occurred in Chinese breed- ing programs during the past 20 years. Relationship between grain and flour traits and quality of raw dumpling Correlation coefficients between quality traits and color of raw dumpling sheets are presented in Table 5. Pro- tein content and total starch content mainly influenced L * value of raw dumpling sheets. Correlation coeffi- cients between protein content, total starch content and L * value at 0 and 2 h after sheeting were -0.46 (P<0.01), -0.52 (P<0.01), 0.55 (P<0.01), and 0.57 (P<0.01), respectively. Parameters relative to protein quality such as water absorption, development time, stability, and maximum resistance showed moderately negative ef- fects on L * and a * values of raw dumpling sheets, and starch pasting peak viscosity, breakdown and final vis- cosity showed slight and positive effects on L * values. Flour yellow pigment was significantly associated with a * and b * values at 0 and 2 h after sheeting, with r=-0.67 (P<0.01), -0.62 (P<0.01), 0.87 (P<0.01), and 0.84 (P<0.01), Table 2 Mean, coefficients of variation (CV), and ranges in grain quality trait parameters for 39 wheat cultivars Trait Mean CV (%) Range Grain hardness 58.9 28.8 20.7-79.0 Protein content (%, 14% MB) 12.6 5.7 11.1-14.3 Water absorption (%) 65.9 6.6 56.1-72.5 Development time (min) 3.8 40.5 1.9-8.3 Stability (min) 6.4 71.6 1.2-17.9 Mixing tolerance index (BU) 1) 53.7 53.4 16.0-140.0 Extensibility (mm) 180.7 14.9 79.2-253.3 Max. resistance (BU) 215.0 57.0 32.5-490.1 Peak viscosity (RVU) 195.8 16.1 114.6-263.6 Breakdown (RVU) 148.5 19.1 60.5-191.8 Final viscosity (RVU) 235.3 15.9 116.2-289.3 Amylose (%) 22.8 2.7 21.2-23.8 Total starch (%) 80.2 1.5 78.1-83.1 Flour yellow pigment (mg kg -1 ) 1.9 29.5 1.2-3.6 Flour PPO [A 475 /(g×min)×10 3 ] 2.7 39.2 0.4-4.7 1) Mixing tolerance index (MTI) was measured by farinograph. Table 3 Mean, coefficients of variation (CV) and ranges of L * , a * , and b * values of raw dumpling sheets and sensory evaluation parameters of boiled dumplings for 39 wheat cultivars Parameter Mean CV (%) Range L * 0 h 84.80 0.8 83.38-85.99 a * 0 h 0.52 89.1 -0.75-1.47 b * 0 h 20.56 11.3 16.56-26.01 L * 2 h 82.47 1.0 80.81-84.37 a * 2 h 0.97 52.3 -0.30-2.09 b * 2 h 23.63 11.5 19.21-28.62 Sensory evaluation Color (20) 13.8 9.0 11.4-16.6 Appearance (20) 14.4 9.0 10.8-16.3 Firmness (20) 13.9 8.9 11.6-16.0 Elasticity (20) 14.3 7.2 12.0-16.4 Stickiness (10) 7.1 7.4 6.1-8.0 Smoothness (10) 7.1 5.1 6.3-7.7 Total score (100) 70.5 4.9 63.5-78.3 The Relationship Between Chinese Raw Dumpling Quality and Flour Characteristics of Shandong Winter Wheat Cultivars 1797 © 2011, CAAS. All rights reserved. Published by Elsevier Ltd. down (r=0.54, P<0.01) and smoothness show that high starch pasting peak viscosity and breakdown gave bet- ter smoothness and stickiness of boiled dumplings (Fig. 2). Flour yellow pigment showed moderate negative effect on boiled dumpling appearance (r=-0.45, P<0.01). Lan et al. (2010) also showed the positive effects of gluten strength on appearance and negative effects on firmness, as well as the positive effects of starch pasting proper- ties on stickiness for dumplings, but did not report the positive effects of flour gluten strength on dumpling elasticity. DISCUSSION Large variations in protein quality parameters in com- parison with starch properties of Shandong winter wheat cultivars were observed. The reason could be that Chinese breeding programs have given priority to improving gluten strength since 1980s and cultivars such as Jinan 17 and Jimai 20 with excellent pan bread making quality were developed. Farinograph and extensograph are routinely used to test advanced lines, therefore quality classification in China are largely de- termined by gluten strength parameters such as farinograph stability. In the present study, the 39 tested genotypes were classified into 11 strong gluten wheats (stability>7.0 min), 17 medium gluten wheats (stability 3.0-7.0 min), and 11 weak gluten wheats (stability<3.0 min) based on farinograph stability. Although starch pasting properties and amylose contents significantly influence textural properties of white salted noodle (Oda et al. 1980; Konik and Miskelly 1992; Konik et al. 1993; Baik and Lee 2003) and dumplings (Lan et al. 2010), little direct selection pressure is applied to improve starch parameters in wheat breeding programs. Therefore, Chinese breeding programs should give more attention to improve starch quality, and to produce balanced flour Table 4 Raw dumpling quality classifications of tested cultivars and lines Classification Score Number of cultivars Rank of cultivar 1) Very good >75.0 2 Jimai 20, Zimai 12 Good 70.1-75.0 21 Zhongmai 155, Yannong 24, Yannong 19, Liangxing 66, Linmai 6, Jimai 076128, Jimai 19, Jimai 5319, Yannong 23, Jimai 077019, Taishan 23, Lumai 21, BPT08058, Jimai 22, Jimai 7251, Jimai 056852, Shannong 15, Jimai 035037, Lumai 23, Jimai 065504, Taishan 24 Fair 65.0-70.0 14 Jining 16, Jimai 6487, Jinan 17, Taishan 223, Tainong 18, Jimai 066324, Taishan 21, Jimai 046402, Jimai 7327-2, Wennong 6, Jimai 077072, Jining 13, Linmai 2, Jimai 6097 Poor <65.0 2 Jimai 037042, Huaimai 8 1) Rank was based on the total raw dumpling score. Table 5 Correlation coefficients between quality traits and raw dumpling sheet color Trait L * 0 h a * 0 h b * 0 h L * 2 h a * 2 h b * 2 h Protein content -0.46 ** 0.17 0.10 -0.52 ** 0.22 0.15 Water absorption -0.36 * 0.33 * 0.01 -0.29 0.24 0.06 Development time -0.41 * 0.29 0.14 -0.40 * 0.26 0.25 Stability -0.34 * 0.31 0.07 -0.31 0.29 0.19 Max. resistance -0.30 0.39 * -0.05 -0.29 0.35 * 0.04 Peak viscosity 0.38 * -0.15 -0.27 0.26 -0.11 -0.30 Breakdown 0.36 * -0.21 -0.16 0.27 -0.17 -0.18 Final viscosity 0.39 * -0.13 -0.08 0.27 -0.08 -0.10 Total starch 0.55 ** -0.32 * -0.15 0.57 ** -0.34 * -0.24 Flour yellow pigment -0.04 -0.67 ** 0.87 ** -0.00 -0.62 ** 0.84 ** Flour PPO -0.32 * 0.27 0.06 -0.40 * 0.19 0.20 * and ** indicate levels of significance at P=0.05 and P=0.01, respectively. The same as below. respectively. Flour PPO activity had slightly negative effects on L * values. These results clearly indicated that protein content and gluten strength, and starch past- ing properties, and total starch content negatively and positively contributed to L * and a * values of raw dump- ling sheets, respectively. Flour yellow pigment showed larger effect on color of raw dumpling sheet than PPO activity. Grain hardness and gluten strength parameters such as farinograph MTI (r=-0.55, P<0.01), extensibility, and maximum resistance (r=0.43, P<0.01) had significant positive correlations with appearance and elasticity of boiled dumpling, but a slight negative effect on firm- ness (Table 6). For example, the correlation coeffi- cients between MTI and appearance and elasticity of boiled dumpling were -0.55 (P<0.01) and -0.54 (P<0.01), respectively (Fig. 1). These results suggest that strong gluten contributes to good boiled dumpling appearance and elasticity, but gave a slightly poorer firmness. However, starch pasting properties were an important factor in determining stickiness and smoothness of boiled dumplings. Breakdown had a positive correla- tion with stickiness (r=0.45, P<0.01). The relation- ships between peak viscosity (r=0.51, P<0.01), break- 1798 ZHANG Yan et al. © 2011, CAAS. All rights reserved. Published by Elsevier Ltd. properties and good noodle and dumpling quality. Chinese wheat cultivar Jimai 20 and Zimai 12 were identified as possessing very good boiled raw dumpling quality and the assessment score of Jimai 20 (78.3) and Zimai 12 (76.0) was clearly higher than that of Chinese commercial flour, Xuehuafen, used as the con- trol (70.0) in this study. This reason should mainly be that flour color of Jimai 20 and Zimai 12 was better than that of Xuhuafen having larger a * value of flour. Jimai 20 was characterized by strong gluten strength and excellent flour color, thus conferring good quali- ties for pan bread and noodle (He et al. 2010). This also suggests that the possibility of developing multi- purpose quality wheat. Previous reports indicated that starch property and flour color play significant roles in determining raw dumpling and noodle quality, but not in pan bread quality (He et al. 2004; Lan et al. 2010). Therefore, the requirement of gluten strength for pan bread was higher than that of starch property and color. However, the requirement in starch property and color for raw dumpling and noodle was stronger than that for pan bread, i.e., the flour from wheat cultivar with strong gluten strength, lower starch peak viscosity, and lower L * values might be suitable for making good quality pan bread, but not for making good quality raw dump- ling and noodle. Based on previous reports, overly strong gluten might have a negative effect on noodle viscoelasticity (Liu et al. 2003; He et al. 2004), starch pasting breakdown positively influenced on smoothness of noodle (Batey et al. 1997); thus flour with medium gluten and better starch pasting properties could be suitable for making good quality noodle. Although raw dumplings and noodles are similar foods produced from wheat flour based on the type for processing (e.g., boiling) used before being supplied to the consumer, this study shows that strong gluten contributes to good boiled dumpling Table 6 Correlation coefficients between quality traits and sensory evaluation parameters of boiled raw dumplings Trait Color Appearance Firmness Elasticity Stickiness Smoothness Total score Grain hardness 0.09 0.35 * -0.40 * 0.17 -0.20 -0.11 0.03 Protein content -0.40 * -0.20 -0.01 0.34 * -0.08 -0.19 -0.15 Water absorption -0.01 0.20 -0.36 * 0.10 -0.11 -0.16 -0.06 Development time -0.19 0.34 * -0.30 0.32 * -0.15 -0.04 0.02 Stability -0.17 0.33 * -0.27 0.31 -0.21 -0.07 0.02 Mixing tolerance index -0.13 -0.55 ** 0.21 -0.54 ** 0.11 -0.09 -0.33 * Energy -0.17 0.43 ** -0.28 0.47 ** -0.11 0.06 0.13 Extensibility -0.06 0.26 0.23 0.45 ** 0.03 0.01 0.30 Max. resistance -0.16 0.43 ** -0.33 * 0.43 ** -0.10 0.05 0.11 Peak viscosity 0.15 -0.07 0.06 0.07 0.21 0.51 ** 0.13 Breakdown 0.24 0.04 -0.00 0.05 0.45 ** 0.54 ** 0.34 * Total starch 0.39 * 0.06 0.20 -0.34 * 0.12 0.16 0.17 Flour yellow pigment -0.03 -0.45 ** -0.05 -0.26 -0.21 -0.31 -0.37 * Flour PPO -0.29 0.19 -0.38 * 0.11 -0.14 -0.10 -0.08 Ç Fig. 1 Association between farinograph mixing tolerance index (MTI) and elasticity of raw dumplings. Fig. 2 Associations between starch pasting peak viscosity (PV), breakdown (BD) and smoothness of raw dumplings. The Relationship Between Chinese Raw Dumpling Quality and Flour Characteristics of Shandong Winter Wheat Cultivars 1799 © 2011, CAAS. All rights reserved. Published by Elsevier Ltd. appearance and elasticity. Therefore, the requirement of gluten strength for raw dumpling was higher than for noodles. However, the requirement in color for raw dumplings is more flexible than for noodles. Pro- tein contents ranging from 11.1-14.3%, with an aver- age of 12.6% in Chinese winter and facultative wheats are generally not the limiting factor. This is also in agreement with observations made by various milling companies in China. It is suggested that breeding pro- grams should give more attention to gluten strength and starch pasting parameters for raw dumpling qual- ity improvement. CONCLUSION Large variations in protein quality parameters in com- parison with starch properties of Chinese winter wheat cultivars were observed. Variation in the color of raw dumpling sheets was broader than that of sensory evalu- ation parameters of boiled dumplings. Two cultivars, Jimai 20 and Zimai 12, were identified as possessing very good quality for raw dumplings. Protein and total starch content significantly influenced L * and a * values of raw dumpling sheets, and fours with lower protein and higher total starch content produced significantly better color of raw dumplings. Flour yellow pigment influenced positively and negatively a * and b * values of raw dumpling sheets, respectively. Flour gluten strength and starch pasting properties positively contributed to elasticity and smoothness of raw dumplings. It is sug- gested that breeding programs should give more atten- tion to gluten strength and starch pasting parameters for raw dumpling quality improvement. 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Raw dump- ling is widely consumed because it is considered to The Relationship Between Chinese Raw Dumpling Quality and Flour Characteristics of Shandong Winter Wheat Cultivars 1793 ©