EFFECTS OF INCORPORATION OF CLEAR FLOUR ON THE QUALITY OF CHINESE NOODLES

Headnote

ABSTRACT

Clear flour, the lowest quality of all commercial grades of flour, was incorporated alone or in combination for making Chinese noodles. Some of the RVA (Rapid Visco Analyzer) parameters and Farinograph parameters of wheat flour-clear flour blends, as well as cooked noodle brightness and whiteness index decrease as the clear flour proportion in the blends increased. The water absorption and the mixing tolerance index for wheat flour-clear flour blends showed the reverse tendency. However, incorporation of clear flour improved the tensile force, the textural attributes of cooked noodle, and revealed the greater mouth-feel and overall acceptance.

- Keywords: clear flour, Chinese noodles, noodles quality -

INTRODUCTION

Clear flour is the by-product of straight flour that remains after patent flour has been removed. Clear flour is darker in color than straight flour and patent flour, as it is made from the part of the endosperm closest to the bran (HUI, 2006). Clear flour may have a protein content as high as 1 7% and an ash content of 0. 7 to 0.8% (GISSLEN, 2005). It is less expensive than patent flour, but the gluten formed from clear flour is typically of less quality than that from patent flour. Clear flour is usually separated into more than one grade (FIGONI, 2007). First clear is dark flour that is often used in rye and whole grain breads, where its dark color is not noticed and its high protein content contributes muchneeded gluten (GISSLEN, 2005).

Chinese noodles, which originated in northern China, are generally made from wheat flour of high protein content (10.5-13.0%), and gradually became a staple food in many Asian countries (HOU and KRUK, 1998; HUANG, 1996; MISKELLY, 1993). Today, they make up more than 40% of the total wheat flour consumed, and have become a popular food source in Asia (CROSBIE et al, 1990). In the simplest form, noodles are prepared from a dough containing wheat flour, water and salt; the procedure involves mixing, resting, compounding, sheeting and cutting (OH et al, 1983). In general, a good quality noodle has a bright and creamy appearance, and a smooth, soft and elastic texture (CROSBIE et al., 1998). Because of the simple formula, the characteristics of protein and starch in wheat flour are known to have important effects on the eating quality of noodles. The chewiness of cooked noodles has a high correlation to protein content as well as to sodium dodecyl sulfate (SDS) sedimentation volume (BAIK et al, 1994). In addition, many reports also indicate that protein quantity and quality of wheat flour are highly correlated with noodle quality, especially hardness (BAIK et al., 1994; HATCHER et al, 1999; KRUGER et al., 1994; MISKELLY, 1984; MISKELLY and MOSS, 1985; MORRIS et al., 2000; OH et al, 1985b; ROSS et al, 1997; TOYOKAWA et al., 1989; YUN et al, 1996).

The importance of the pasting properties of starch to the texture of cooked noodles has been well-documented (CROSBIE, 2005). Noodles made from flour with high swelling starches have softer texture than those with low swelling starch (FU, 2008). In addition, starch properties appear to play a role in instant noodle quality; some manufacturers prefer flour with low gelatinization temperatures for rapid hydration during cooking (FU, 2008). Many researches point out that wheat flour with low amylose content, high peak paste viscosity as well as high gelatinization temperature and enthalpy provide white salted noodles with the preferred soft and elastic eating texture (BAIK and LEE, 2003; KONIK et al., 1992; MIURA and TANII, 1993; MORRIS, 1998; TOYOKAWA et al., 1989; ZHAO et al, 1998).

Previous studies have focused on the issue of understanding the role of lipids, protein and starch properties on the textural qualities of noodles. However, relatively little attention has been devoted to the influence of clear flour used alone or in combination on the quality attributes of noodles. In our pretest, clear flour was used to replace partially wheat flour to successfully make noodles. Hence, the objective of this study was to illustrate the potential of incorporating increasing amounts of clear flour with wheat flour for making noodles. In this study, different ratios of clear flounwheat flour were mixed to form the dough and then made into noodles. The pasting properties, farinograph characteristics of clear flour-wheat flour blends were evaluated, as was the qualities of the noodles, including: color, tensile force, tensile distance, as well as textural and sensory properties. Our aim was to develop Chinese noodles with clear flour, which exhibit the consumer -satisfying texture and taste.

MATERIALS AND METHODS

Materials

Wheat flour with medium strength and clear flour were purchased from Lien Hwa Fukang plant (Taoyuan County, Taiwan). Clear flour was obtained by milling of hard red spring wheat. Clear flour has a concentrate particle size distribution between 50-125 µm, and wheat flour has a particle size between 25-200 µm.

Preparation of flour blends

Wheat flour was blender with clear flour in ratios of 0:100, 15:85, 25:75, 50:50, and 100:0 (wheat flour: clear flour, w:w).

Chemical analysis of flours

Protein, lipid, ash, dietary fiber (DF), soluble DF, and insoluble DF content of samples were determined according to Approved Methods 44-15A, 46-13, 30-20, 08-01, and 32-21, respectively (AACC methods, 2000). The peak (PV), holding strength (HS), breakdown (BV), final (FV), and setback (SB) viscosities were determined using the RVA SUPER 3(Newport Scientific, Australia) according to AACC Method 76-21 (AACC methods, 2000). The water absorption (WA), dough development time (DDT), dough stability (DS), mixing tolerance index (MTI), and dough breakdown time (DBT) were determined using a Brabender Farinograph Resistograph according to AACC Method 54-21 (AACC methods, 2000).

Noodles color measurement

Colors (L*, a*, and b* values) of flours and dough sheet were measured, in triplicate, with a chromameter (CR-410, Konica Minolta, Tokyo, Japan). A white tile (L* 92.30, a* 0.32, and b* 0.33) was used as standard. The L*, a* and b* data were transformed to a Whiteness Index score using the equation 100-[(100-L)2+a2+b2]05 (BOLIN and HUXSOLL, 1991). Dough sheet color measurements were taken on each side of the two reserved dough sheets at 0 and 24 h after sheeting.

Cooking properties and textural analysis of noodles

Noodles preparation

The Chinese white salted noodles of this study were prepared by initially mixing the wheat flour and clear flour in different ratios, namely, 100:0, 85: 15, 75:25, 50:50, and 0: 100. The experiment was replicated three times. To this mixture was added 2% NaCl and 30% distilled water (on flour basia) (in the previous test, 30% water added can maintain the structure of dough sheet). The suspension was mixed at low speeds for 2 min and then for 4 min at higher speed in a Spar mixer. The dough was allowed to rest in a polyethylene bag for 30 min then rolled into a 3-mm thick sheet, folded, and rolled into a 5-mm thick sheet. These steps were repeated twice. After resting for an addition 30 min, the thickness of the dough sheet was reduced by pressing it through rollers with a gap of 1.2 mm. The dough sheet was cut into 0.33x30 (widthxlength) strands and stored in a plastic bag for 1 h before cooking and texture evaluation. Raw noodles were cooked in boiling distilled water (1:10, w/w), then rinsed with cool water, drained, wiped using paper towels, and kept covered in Petri dishes for 5 min at room temperature before the TPA analysis.

Cooking loss and cooking yield

Cooking yield and cooking loss of the noodles were determined as described in AACC method 66-50 (AACC methods, 2000). Thirty grams of the noodles were added to a beaker containing about 300 mL of boiling water. The beaker was covered with a watch glass and cooked for 5 min (the optimum cooking time, measured according to AACC Method 16-50, 2000) with slight agitation. The cooked noodles allowed to drain for 5 min and were then weighed and the cooking yield calculated. Cooking loss was determined by evaporating the cooking water in a hot air oven at 105°C to constant weight.

Tensile force and distance

Tensile force and distance of cooked noodles were measured on a TA-XT2Ì® Texture Analyser (Stable Micro Systems, Surrey, England), using Spaghetti Tensile grips (A/SPR) at a pre-test speed of 10 mm/ sec, a test speed of 10 mm/ sec and a post-test speed of 10 mm/sec. Noodles were tested individually within 5 min after cooking and night noodles strands from the different batches were measured for each sample.

Texture analysis

TPA (Texture profile analysis) of cooked noodles was performed with a 3.5 mm radius probe. Instrument settings were compression mode, trigger type, auto; pretest speed, 2.0 mm/s; posttest speed, 5.0 mm/s; test speed, 1.0 mm/s; compression, 50%; interval between two compressions, 1 s; load cell, 5 kg. From force-distance curves, five texture parameters can be obtained: hardness (g), springiness, cohesiveness and resilience (EPSTEIN et al, 2002). Noodles were tested individually within 5 min after cooking and night noodles strands from the different batch were measured for each sample.

Sensory evaluation

The sensory evaluation of noodles was performed with an evaluation panel of 12 trained members. They were professionally trained for evaluating the following characteristics: appearance, color, mouth feel, and overall using a 1-7 hedonic scale. The scale is verbally anchored with seven categories, as follows: extremely like, very like, like, neither like or dislike, dislike, very dislike, and extremely dislike.

Statistical analysis

Analysis of variance and the significance of differences among samples were, respectively, analyzed with the ANOVA procedure and Duncan's multiple range test of the SAS for Windows R 6.12 (SAS Institute Inc., Cary, NC).

RESULTS AND DISCUSSION

Flour quality characteristics

The values in wheat flour and clear flour of total dietary fiber content (TDF) were 2.67 and 4.74%, respectively, of which soluble dietary fiber (SDF) contents were 0.48 and 0.37% and insoluble dietary fiber (IDF) contents were 2.19 and 4.37%, respectively (Table 1). Indeed, significant improvements in the amount of DF can be made by incorporating clear flour into noodles generally made from wheat flour, which are not generally considered to be a good source of fiber.

Flour protein, ash content and flour -pasting characteristics are major specifications for achieving the desired eating quality of each noodle type (HOU and KRUK, 1998). The content of protein, lipid, ash, total dietary fiber, and insoluble dietary fiber were higher in clear flour than in wheat flour (Table 1). Generally, protein content has a positive correlation with noodle hardness, and a negative correlation with noodle brightness. Thus, there is an optimum protein content of flour required for each noodle type (HOU and KRUK, 1998). Chinese noodles require hard wheat flour with high protein content ( 1 0. ?13. 1%), giving a firmer bite and springy texture (BAIK et al., 1994; HOU and KRUK, 1998). In our research, clear flour was obtained by milling hard red spring wheat cultivar. Its 18.78% protein content provided more protein to improve the texture of noodles and showed a greater quantity than that of soft wheat cultivar ( 12.7%) (FUSTIER et al, 2007).

Flour ash content has been rated as one of the important specifications because it negatively affects noodle color. Flour ash content is largely determined by the wheat's ash content. Wheat with an ash content of 1.4% or less always enjoys an advantage (HOU and KRUK, 1998). In our search, wheat flour of 0.4% ash content is usually suitable for making premium quality noodles. With the addition of clear flour of 1.18% ash content an undesirable color of noodles may result. Sometimes, flour color may be more related to noodle color. Flour color L*>90 measured with Chroma Meter is often required (HOU and KRUK, 1998). Clear flour of L*89.37 (Table 1), close to the standard stated above, should not significantly influence the color of noodles.

Finally, the pasting characteristics of flour (as measured on the amylograph or Rapid Visco Analyzer) also play an important role. Previous results reported that peak paste viscosity was highly correlated to the organoleptic eating quality of Japanese- and Korean-style white salted noodles (PANOZZO and MCCORMICK, 1993). RVA peak viscosity, holding strength and breakdown were the main indicted quality parameters of noodles, which significantly correlated positively with stickiness, appearance, smoothness, and total score (LIU et al, 2003; KONIK and MOSS, 1992). In our research, all RVA parameters of wheat flour were higher than those of clear flour (Table 2). This may be attributed to the higher dietary fiber in clear flour. So, the presence of clear flour in the flour will reduce all RVA parameters, thereby influence the eating quality of noodles.

Dough properties measured by farinograph are often also included in noodle flour specifications because they affect noodle processing behavior and noodle eating quality (HOU and KRUK, 1998). Incorporation clear flour at 0, 15, 25, 50 and 100% levels revealed differences to the dough mixing behavior as measured by the Farinograph. Table 3 shows the main parameters registered in the farinogram. The addition of clear flour at different levels mainly caused an increase in the farinograph water absorption from 19.7 to 23.42%. This phenomenon would be contributed to the higher fiber content of clear flour because the incorporation of high fiber ingredients results in a dramatic increase in the amount of water required to make a dough (IZYDORCZYK et al., 2005).

Dough development time and breakdown time were decreased slightly by the addition of clear flour at 15 and 25%, and rapidly by 50 and 100%. The stability time of clear flour is one third that of wheat flour. But, it was increased with the incorporation of 1 5 and 25% clear flour in the flour blends, and with a rapid decrease at 50%. Stability, in general, gives some indication of the tolerance of mixing the flour (FAUBION and HOSENEY, 1989). The higher protein content of clear flour would increase the tolerance when the incorporation of 1 5 and 25% clear flour in the mixture. However, decrease of tolerance results in weakness of the flour blends, as the DF content increased with increasing clear flour from 50 to 100%. Mixing tolerance index, the degree of softening during mixing, increased slightly at the incorporation of 1 5 and 25% clear flour. Although clear flour generally contained a higher percentage of protein than did wheat flour, the quality of the protein was lower, significantly influencing the farinograph parameters. Overall, from the farinograph results, the incorporation of 15 and 25% clear flour was acceptable.

Raw noodle color

The influence of time-dependent color changes in raw noodles prepared by incorporating clear flour can be seen in Table 4. Significant linear decreases (R^sup 2^=0.9908) in raw noodle brightness (L*) were observed with the progressive increase in clear flour content. Coincident with this was a general decrease in the raw noodle whiteness index (W.I.). Furthermore, 24-hour storage at room temperature of raw noodles also showed the same tendency, but the values were less than the counterparts of fresh noodles (O-hour storage). There was a linear increase in raw noodle redness, a*. Therefore, the observed changes can be attributed to the color of clear flour being darker than wheat flour which was proved by the value of W.I. of clear flour to be less than that of wheat flour (Table 1).

Quality of noodles

Noodle qualities were evaluated by solid loss during cooking, tensile strength and textural tests. The results indicated that incorporating clear flour insignificantly affected the solid loss of cooked noodles in 5 minutes of cooking time (Table 5). The previous observation was that the quantity of protein content in noodles will not affect its cooking loss (OH et ed., 1985a). Thus, incorporating clear flour with higher protein content in noodles showed an insignificant influence in the solid loss of cooked noodles. However, the cooking yield of noodles was decreased by increasing the addition of clear flour (Table 5). The water absorption of noodles prepared from clear flour, about 29.17%, is less than that of wheat flour (32.93%) with 5 minutes of cooking time (data not shown). Therefore, the addition of clear flour would decrease the cooking yield of noodles.

The tensile forces of cooked noodles were increased with the increased incorporation of clear flour. The cooked noodles containing 100% clear flour were found to have a similar tensile distance compared to 100% wheat flour. However, incorporating clear flour improves the tensile distance of cooked noodles, and incorporating 20% clear flour revealed the maximum tensile distance (Table 5).

Texture profile analysis (TPA) results of cooked noodles prepared with 100:0, 85:15, 75:25, 50:50, and 0:1 00 wheat flour: clear flour are summarized in Table 5. According to the previous observation, hardness of cooked noodles increased significantly as protein content was increased (PARK et ed., 2003). When the noodles were made from clear flour with higher protein content, they showed higher scores for hardness and chewiness. Thus, by increasing the incorporation of clear flour from 25 to 100%, these parameters increased significantly. Meanwhile, hardness and chewiness of noodles were insignificantly influenced by the incorporation of 15% clear flour. Otherwise, springiness and cohesiveness of cooked noodles were not influenced by the incorporation of clear flour. A similar phenomenon was observed in resilience, although noodles prepared with 100% clear flour had the higher resilience (Table 5). Several investigations reported that noodles made from wheat flour with high protein had higher scores for hardness, cohesiveness and chewiness (BAIK et al., 1994; PARK et al, 2003). Thus, the higher protein content in clear flour would be the major factor influencing the textural properties of noodles prepared with clear flour-wheat flour blends.

Sensory evaluation of noodles prepared with wheat flour and clear flour

The sensory evaluations of noodles prepared with 100:0, 85:15, 75:25, 50:50, and 0:100 wheat flour: clear flour were compared for appearance, color, mouth feel, and overall acceptance. The appearance of noodles is important to consumers. The results indicated a nearly statistical similarity for the appearance of noodles with 0, 15, and 25% clear flour; noodles with 50 and 100% clear flour revealed the worst appearance. Similarly, the color of noodles showed the same phenomenon, and noodles with 100% clear flour had the worst value of color. The poor appearance and color of noodles with clear flour are attributed to the darker color of clear flour. However, the mouth feel and overall result were not significantly affected by the incorporation of clear flour, even at the 100% substitution (Table 5).

CONCLUSIONS

It is possible to produce noodles of acceptable texture from wheat flour containing clear flour, even when the substitution of clear flour is up to 100%. Noodle color is really influenced by the original color of clear flour. In addition, the pasting and farinograph characteristics of wheat flour-clear flour blends are significantly affected by the substitution of clear flour above 25%. Therefore, the textural and sensory properties of cooked noodles reveal a positive improvement from adding clear flour. From the viewpoint of consumer acceptance, noodles made with clear flour will ultimately be welcomed in the marketplace. Meanwhile, the use of clear flour in noodle manufacturing will decrease the cost and improve the added-value of clear flour. Overall, Data from this study can be used for the development of clear flour-based products. It also provides a basis for clear flour-wheat flour blends and quality evaluation in the noodle manufacturing industry.

References

REFERENCES

AACC (American Association of Cereal Chemists), 2000. In: Approved Methods of The AACC- Method, 10th Ed. USA, St. Paul, MN.

Baik B.K., Czuchajowska Z. and Pomeranz Y. 1994. Role and contribution of starch and protein contents and quality to texture profile analysis of oriental noodles. Cereal Chemistry 71: 315-320.

Balk B.K. and Lee M.R. 2003. Effects of starch amylose content of wheat on textural properties of white salted noodles. Cereal Chemistry 80: 304-309.

Bolin H.R. and Huxsoll C.C. 1991. Control of minimally processed carrot Daucus carota) surface discoloration caused by abrasion peeling. Journal of Food Science 56: 416-418.

Crosbie G.B. 2005. Defining and developing tests to meet the key wheat quality requirements of Asian foods. In: Blanchard CL., Truong H., Allen H.M., Blakeney A.B. and O'Brien L. (Eds.), Cereals 2005: Proceedings of the 55th Australian cereal chemistry conference and AACCI pacific rim symposium. Royal Australian Chemical Institute, Australia, pp. 32-36.

Crosbie G.B., Huang S. and Barclay LR. 1998. Wheat quality requirements of Asian foods. Euphytica 100: 1 55- 1 56.

Crosbie G.B., Miskelly D.M. and DewenT. 1990. Wheat quality for the Japanese flour milling and noodle industries. Western Australian Journal of Agriculture 31: 83-88.

Epstein J., Morris CF. and Huber K.C. 2002. Instrumental texture of white salted noodles prepared from recombinant inbred lines of wheat differing in the three granule bound starch synthase (Waxy) genes. Journal of Cereal Science 35: 51-63.

Faubion J.M. and Hoseney RC 1989. The viscoelastic properties of wheat flour doughs, in Dough Rheology and Baked Product Texture. In: Faridi H. and Faubion J.M. (Eds.) AVI, New York, USA.

Figoni P. 2007. In: Figoni P. (Ed.) How baking works: Exploring the fundamentals of baking science, John Wiley & Sons, New York, USA, p. 416.

Fu BX. 2008. Asian noodles: History, classification, raw materials, and processing. Food Research International 41: 888-902.

Fustier P., Castaigne F, Ttirgeon S.L. and Biliaderis CG. 2007. Semi-sweet biscuit making potential of soft wheat flour patent, middle-cut and clear mill streams made with native and reconstituted flours. Journal of Cereal Science 46: 13.

Gisslen W. 2005. In: Gisslen W. (Ed.) Professional Baking, John Wiley & Sons, New York, USA, p. 35.

Hatcher D.W., Kruger J.E. and Anderson M.J. 1999. Influence of water absorption on the processing and quality of oriental noodles. Cereal Chemistry 76: 566-572.

Hou G. and Kruk M. 1998. Asian noodle technology. Technical Bulletin 20: 1-10.

Huang S. 1996. China. The world's largest consumer of paste products. In: Kruger J.E., Matsuo R.B. and Dick J.W. (Eds.), Pasta and noodle technology. AACC, St. Paul, Minnesota, pp. 301-325.

Hui Y.H., 2006. Sourdough bread Handbook of food science, technology and engineering. Taylor & Francis Group, New York, USA, p. 928.

Izydorczyk M.S., Lagass S.L., Hatcher D.W., Dexter J.E. and Rossnagel B.G. 2005. The enrichment of Asian noodles with fiber-rich fractions derived from roller milling of hullless barley. Journal of the Science of Food and Agriculture 85: 2094-2104.

Láu J.J., He Z.H., Zhao Z.D., Pena R.J. and Rajaram S. 2003. Wheat quality traits and quality parameters of cooked dry white Chinese noodles. Euphytica 131: 147-154.

Konik CM., Miskelly D.M. and Gras P.W. 1992. Contribution of starch and non-starch parameters to the eating quality of Japanese white salted noodles. Journal of the Science of Food and Agriculture 58: 403-406.

Konik CM. and Moss R. 1992. Relationship between Japanese noodle quality and RVA paste viscosity. Proceedings of the 42nd Australian Cereal Chemistry Conference, Christchurch, New Zealand (V.J. Humphrey-Taylor Ed.), pp. 209-212.

Kruger J.E., Anderson M.H. and Dexter J.E. 1994. Effect of flour refinement on raw Cantonese noodle color and texture. Cereal Chemistry 71: 177-182.

Miskelly D.M. 1984. Flour components affecting paste and noodle colour. Journal of the Science of Food and Agriculture 35: 463-471.

Miskelly D.M. 1993. Noodles. A new look at an old food. Food Australia 45: 496-500.

Miskelly D.M. and Moss H.J. 1985. Flour quality requirements for Chinese noodle manufacture. Journal of Cereal Science 3: 379-387.

Miura H. and Tanii S. 1993. Endosperm starch properties in several wheat cultivars preferred for Japanese noodles. Euphytica 72: 171-175.

Morris CF. 1998. Evaluating the end-use quality of wheat breeding lines for suitability in Asian noodles. In: Blakeney A.B. and O'Brien L. (Eds.), Pacific people and their food, The American Association of Cereal Chemists. St. Paul, MN, USA, pp. 91-100.

Morris CF., Jeffers H.C. and Engle D.A. 2000. Effect of processing, formulae and measurement variables on alkaline noodle color-Toward an optimized laboratory system. Cereal Chemistry 77: 77-85.

Oh N., Sieb P., Beyoe C and Ward A. 1985a. Noodles: II. The surface firmness of cooked noodles from soft and hard wheat flours. Cereal Chemistry 62: 431-436.

Oh N.H., Seib P.A., Deyoe C.W. and Ward A.B. 1983. Noodles. I. Measuring the textural characteristics of cooked noodles. Cereal Chemistry 60: 443-438.

Oh N.H., Seib P.A., Ward A.B. and Deyoe C.W. 1985b. Noodles. IV. Influence of flour protein, extraction rate, particle size, and starch damage on the quality characteristics of dry noodles. Cereal Chemistry 62: 441-446.

Panozzo J.F. and McCormick K.M. 1993. The Rapid Viscoanalyser as a method of testing for noodle quality in a wheat breeding programme. Journal of Cereal Science 17: 25-32.

Park CS., Hong B.H. and Baik B.K. 2003. Protein quality of wheat desirable for making fresh white salted noodles and its influences on processing and texture of noodles. Cereal Chemistry 80: 297-303.

Ross A.S., Quail K.J. and Crosbie G.B. 1997. Physicochemical properties of Australian flours influencing the texture of yellow alkaline noodles. Cereal Chemistry 74, 8 14-820.

Toyokawa H., Rubenthaler G.L., Powers J.R. and Schanus E.G., 1989. Japanese noodle qualities. I. Flour components. Cereal Chemistry 66: 382-386.

Yun S.H., Quail K. and Moss R 1996. Physicochemical properties of Australian wheat flours for white salted noodles. Journal of Cereal Science 23: 1 8 1 - 1 89.

Zhao X.C, Batey I.L., Sharp P.J., Crosbie G., Barclay I., Wilson R., Morell M.K. and Appels R. 1998. A single genetic locus associated with starch granule properties and noodle quality in wheat. Journal of Cereal Science 27: 7-13.

Paper received October 17, Accepted March 15, 2012