Effects of Adding Radicchio (Cichorium Intybus L.) Powder to Rice Cakes

Progress in Nutrition 2018; Vol. 20, Supplement 1: 246-254 DOI: 10.23751/pn.v20i1-S.6104 © Mattioli 1885 Original article Effects of adding radicchio (Cichorium intybus L.) powder to rice cakes (Sulgidduk) on the quality Hyeonbin O, Ka-Young Song, Yangyang Zhang, Young-Soon Kim Department of Food and Nutrition, Korea University, Seoul, Republic of Korea - E-mail: [email protected] Summary. This study investigated the quality, antioxidant activities, and sensory properties of Sulgidduk (rice cakes) upon the addition of radicchio (Cichorium intybus L.) powder, which is known to have antioxidant and anti-diabetic effects. Radicchio powder was freeze-dried, passed through a 40-mesh sieve, and used to replace 0%, 0.5%, 1%, 2%, 3%, or 4% of the rice flour. The content of moisture in Sulgidduk did not significantly dif- fer among samples (p<0.05). As the amount of radicchio powder increased, the pH value decreased slightly. Regarding color, the L-value decreased from 84.44 (control) to 45.91 (4% sample), and the a-value increased from -1.16 (control) to 5.20 (4% sample). The b-value increased from control to 2% samples, but then gradually decreased in the 3% and 4% samples. Though hardness and chewiness increased upon adding radicchio powder, the springiness and cohesiveness of the radicchio Sulgidduk samples were reduced when compared to these of the control samples (84.43% and 78.17%, respectively). Antioxidant activity of Sulgidduk increased significantly upon the addition of radicchio. For sensory evaluation, the 1% sample received the highest score (5.35) in overall acceptability. From these results, we determine that addition of 1% radicchio powder to Sulg- idduk is suitable for producing the rice cake. Key words: gantioxidant activities, quality, rice cake, radicchio, sensory evaluation Introduction Rice (Oryza sativa L. ssp. japonica) is a staple food in South Korea. However, rice consumption has been Radicchio (Cichorium intybus L.), a cultivar of gradually reduced in Korea because of changing di- chicory, is a red leafy vegetable that originated in Italy etary habits associated with modernization. Accord- (1). This plant is frequently consumed in salads in win- ing to the 2014 Food Grain Consumption Survey Re- ter in Europe and the United States owing to its ability port from Statistics Korea, annual rice consumption to grow well at low temperatures (2). In Korea, radic- per capita has undergone a continuous decline since chio is cultivated in the Kangwon and Chungbook 1981, falling from 80.7 kg in 2005 to 65.1 kg in 2014 areas. Unlike other chicory cultivars, radicchio (or (10). Thus, many researchers have shown interest in “red chicory”) is rich in polyphenols and anthocyanin the development and study of various processed rice pigments (3). Anthocyanin pigments are natural pur- products. In particular, interest in dduk, Korean tradi- ple pigments with anti-cancer and antioxidant effects tional rice cakes that use rice as a main ingredient, is (4-6). Several studies have reported that anthocyanin increasing. pigments provide health benefits, such as improved Dduk is composed of non-waxy rice, beans, and cognitive function and reduced risk of obesity and car- other grains cultivated under various climatic condi- diovascular diseases (7-9). tions in Korea (11). It is widely used in many agricul- Effects of adding radicchio powder to rice cakes on the quality 247 tural rituals and traditional festivals (12). Sulgidduk, a Table 1. Formulae for Sulgidduk (rice cake) containing different type of traditional Korean dduk, is made by steaming levels of radicchio powder a mixture of non-waxy rice flour and sugared water. Ingredients (g) Additional ratio of radicchio powder (%) Sulgidduk is the standard for studies of Korean rice 0 0.5 1 2 3 4 cakes because of its simple recipe, ease of adding in- Rice powder 500 497.5 495 490 485 480 gredients, and diverse applications (13). Radicchio powder 0 2.5 5 10 15 20 Moreover, investigators have sought to develop methods that can contribute to functional enhance- Sugar 50 50 50 50 50 50 ments of dduk in order to meet the needs of modern Water 50 50 50 50 50 50 society, which seeks a healthy diet and focuses on the Salt 5 5 5 5 5 5 nutritional value of food (14-16). Numerous studies have recently explored the addition of a variety of healthy functional ingredients to Sulgidduk, creating 8-inch-diameter steamer and steamed for 20 min. All nutritionally enhanced Sulgidduk with unique colors samples were sealed in plastic bags and stored at room and flavors (17-20). temperature (25°C) before performing quality meas- The purpose of this study was to analyze the effect urements. of adding different amounts of radicchio powder on Quality analysis the quality, antioxidant activity, and consumer accept- Determination of moisture content and pH value ability of Sulgidduk when compared to the standard The moisture content of the Sulgidduk was meas- recipe. ured using a moisture analyzer (MB35, OHAUS, Zurich, Switzerland). Five grams of each sample was taken from the central part of the Sulgidduk. The pH Materials and methods values of the Sulgidduk were measured by a pH me- ter (SP-701, Suntex instruments Co. LTD., Taipei, Preparation of Sulgidduk Taiwan). Ten grams of Sulgidduk sample was homog- White rice (produced in Gyeonggi, Korea) pur- enized with 90 mL of distilled water by a homogenizer chased in October 2014 was soaked in water for 24 (Unidrive 1000D, CAT Scientific, Staufen, Germany) h, dried in a sieve for 30 min, ground using a roller to measure pH value. mill (DK 101, Donggwang Ltd, Daegu, Korea), and passed through a 20-mesh sieve to produce non-waxy Color measurement rice flour. Refined sugar (CJ, Incheon, Korea) and The surface color of the Sulgidduk was evaluated salt (CJ, Incheon, Korea) were purchased for mak- using a colorimeter (CR-400, Konica Minolta, Osaka, ing the Sulgidduk. Radicchio (produced in Kangwon, Japan) with the Hunter L, a, b color system. The pa- Korea) was purchased in March 2015. Washed radic- rameters L (lightness), a (redness), and b (yellowness) chio leaves were separated, freeze-dried using a freeze were measured. TheΔ E (total color difference) values dryer (FD8508, Ilshin Biobase Co. LTD., Gyeonggi, were defined as in Eq. 1: Korea), ground using a high-speed grinder (CRT-04, Hungchuan Machinery Enterprise, Taipei, Taiwan), ∆E= √(∆L)2 + (∆a)2 + (∆b)2 (1) and passed through a 40-mesh sieve to produce radicchio powder. Sulgidduk samples were prepared with Where ∆L, ∆a, and ∆b are the difference of L, a, the ratios presented in Table 1 (21, 22). Rice flour was and b values between a white board (L: 96.90, a: 0.45, mixed with water until all wet lumps were broken and b: 1.49) and sample, respectively. the rice flour was uniformly wet, and then sifted twice with a 20-mesh sieve. Radicchio powder was substi- Texture analysis tuted for 0.5%, 1%, 2%, 3%, or 4% of the rice flour Textural properties (hardness, chewiness, springi- and mixed with sugar. The mixture was spread into an ness, and cohesiveness) of Sulgidduk were analyzed by 248 Y. O, K-Y Song, Y. Zhang, et al. a rheometer (Sun rheometer Compac-100 II, Sun Sci- ple extracts were centrifuged at 3000 rpm for 10 min entific Co. LTD., Tokyo, Japan). Samples were cut into (Universal 32 R, Hettich, Tuttlingen, Germany) and a fixed size (2 cm × 2 cm × 2 cm). Operation conditions filtered through Whatman No. 1 filter paper. of the rheometer were as follows: No.1 Φ20 mm prove; maximum weight, 2 kg; distance, 33%; table speed, 120 Total polyphenol and flavonoid contents mm∙min-1; 2 bites. The total polyphenol content of Sulgidduk sample extracts was determined by using the Folin-Denis Retrogradation analysis from isothermal crystallization method with slight modifications as suggested by kinetics Hong et al. (25). Fifty microliters of 0.9 M Folin- Retrogradation analyses of Sulgidduk with radic- Ciocalteu reagent ( Junsei Chemistry, Tokyo, Japan) chio were conducted with reference to the method of and 150 μL of 20% (w/v) sodium carbonate solution Kim & Chung (23). Hardness of Sulgidduk preserved (Merck kGaA, Darmstadt, Germany) were added at 4°C for 12, 24, 36, and 48 hours were measured by to 10 mL of sample with 790 mL of distilled water. rheometer (Sun rheometer Compac-100 II, Sun Sci- After incubation at room temperature (25°C) for 30 entific Co. LTD.). Changes in hardness were analyzed min in the dark, the absorbance at 750 nm of the solu- by the Avrami equation described by Kim (24). The tion was measured using a microplate reader (Infinite basic form of the Avrami equation (Eq. 2) is as follows: 200 PRO, Tecan, Mannedorf, Switzerland). A standard curve was plotted using gallic acid (Merck kGaA, Darmstadt, Germany) by the same procedure above. (EL-Et) θ = = e-ktn (2) The total polyphenol content was expressed as gallic (EL-E0) acid equivalents (GAE) per 1 gram of sample. Total flavonoid content of Sulgidduk was meas- Where θ is the fraction of non-crystallized mate- ured using the method described by Davis (26). One rial, k is the rate constant, n is the Avrami exponent, t milliliter of sample was mixed with 150 μL of 5% (w/w) is the storage time (hours), EL is the maximum hard- sodium nitrite ( Junsei Chemistry, Tokyo, Japan) and ness, E0 is the hardness at 0 hours, and Et is the hard- kept into a dark room (25°C). After 6 minutes, 300 μL ness at t hours. of 10% (w/w) aluminum chloride ( Junsei Chemistry, The maximum hardness was determined by meas- Tokyo, Japan) was added and incubated for another 5 uring the hardness of each sample stored at 4 C for min.

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