Food Sci. Technol. Res., 8 (1), 80–84, 2002 Food Components in Fractions of Quinoa Seed Hitomi ANDO,1 Yi-Chun CHEN,2 Hanjun TANG,2 Mayumi SHIMIZU,2 Katsumi WATANABE2* and Toshio MITSUNAGA2 1Kyoto Bunkyo Junior College, Kyoto 611-0041 Japan 2Department of Food and Nutrition, Faculty of Agriculture, Kinki University, Nara 631-0052 Japan Received September 21, 2001; Accepted December 13, 2001 Whole quinoa grain was separated into bran and milled grain, and the milled grain into perisperm and embryo. The proximate composition of the milled grain was similar to that of whole grain. The protein and lipid content of the embryo was 57% of total protein and 49% of total lipid, respectively. Mineral analysis showed that the quinoa grain was rich in K, Mg, Ca, P and Fe. The perisperm contained large oval starch aggregates 20–30 ␮m in diameter and polygonal granules around 1 ␮m in diameter. Differential scanning calorimetry data indicated a gelatinization tem- perature of 54.0 to 71.0˚C and enthalpy of 11.0 J/g starch. The water-soluble protein and NaCl-soluble protein frac- tions composed 28.7–36.2% and 28.9–32.9% of total protein in each fraction. Unsaturated fatty acid accounted for 87.2–87.8% of total fatty acid. Phytate, a trypsin inhibitor activity and lipoxygenase activity in the embryo were high- est. The saponin content of the bran was 86% of total saponin. Keywords: quinoa seed, proximate composition, mineral, starch, protein, lipid, antinutrients Quinoa (Chenopodium quinoa Willd) is a traditional food crop mercial suppliers. in several South American countries which has been attracting Chemical analysis Moisture, ash, protein and lipid con- attention because of the nutritional value of its protein (Ranhotra tents were determined by the AOAC method (Horwiz,1970). et al., 1993). Quinoa grain is a disc-shape, about 2 mm in diame- Dietary fiber was measured by the enzyme-weight method ter and 0.5 mm in thickness. The major anatomical parts of the (Prosky et al., 1988). Sugar content (%) was calculated by sub- grain are the pericarp, the perisperm and the embryo. The peri- tracting moisture, ash, protein, lipid and dietary fiber contents carp (bran) usually contains saponins, which are bitter antinutri- from 100%. Each mineral, with the exception of phosphorus, in tional compounds (Mastebroek et al., 2000). Therefore, milled the sample solutions prepared by the HCl-extract method (Yasui grain with the pericarp removed is used as food. The embryo of et al., 1985) was measured with an atomic absorption spectro- the milled grain wraps around the perisperm like a headband. photometer (HITACHI Z-6100). Phosphorus was determined The high nutritional value of quinoa grain is due mainly to its colorimetrically with ammonium molybdate and ammonium high content of good quality protein (Mahoney et al., 1975, vanadate (Yasui, 1996). Phytate phosphorus and total saponin Gross et al., 1989, Ranhotra et al., 1993). Studies of quinoa lipid were determined by the colorimetric method (Huang & Lantz- (Koziol, 1992), starch (Atwell et al., 1983, Lorenz, 1990), miner- sch, 1983) and the gravimetic method (Lalitha et al., 1987), al (Bruin, 1964) and antinutritional compounds (Chauhuhan et respectively. Trypsin inhibitor activity was assayed (Mitsunaga, al., 1992, Mastebroek et al., 2000) have been carried out. How- 1979) using ␣-N-benzoyl–D, L-arginine-p-nitroanilide as sub- ever, the food components of quinoa grain fractions have not strate. Lipoxygenase activity was measured by the conjugated been investigated. diene method (Takamura & Matoba, 1992). The objectives of this study were to characterize the distribu- Preparation and properties of starch granules Starch tion of food components in quinoa grain fractions and evaluate granules were prepared from the perisperm by a modified alkali the food value of this grain. method (Tang et al., 2000). The distribution of granule size was examined with a particle size analyzer (HORIBA Ltd, LA-700 Materials and Methods type). The shape and size of the granules was observed by scan- Materials Quinoa grain (Chenopodium quinoa Willd cul- ning electron microscopy (NIPPON DATAM, JSM-5400 LV). tivar Real TKW 2.8 g) grown in Bolivia in 1998 was used. X-ray diffraction was performed on the starch (10% moisture) Whole grain (Fig. 1A) was polished to separate the milled grain with an X-ray diffractometer (RIGAKU, Ltd, Rint-2000 type). (Fig.1B) and the bran (pericarp) with a rice milling machine Differential scanning calorimetry (DSC) was performed with a (SHIN-NAKANO KOGYO Ltd. MINI RICE POLISHING RP- starch to water ratio of 5 mg to 20 ␮l (RIGAKU Ltd., DSC- 5). The milled grain was then divided into the perisperm (Fig. 8240D). Iodine absorption spectra and ␤-amylolysis limit were 1C) and the embryo with this machine and sieves. Whole grain, measured following the methods of Takeda et al. (1983). milled grain, bran, perisperm and embryo were ground with a Determination of the amount of protein in each fraction mill for use as samples. All chemicals were purchased from com- Protein was extracted with H2O, 0.5 M NaCl, 60% n-propanol and 1% lactic acid solutions, successively, by the modified Maes method (Mitsunaga & Mitsuda, 1975). Insoluble protein was cal- *To whom correspondence should be addressed. E-mail: [email protected] culated by subtracting soluble protein from total protein. Food Components in Quinoa Seed 81 Fig. 1. Scanning electron microscopy of quinoa grains and starches. A, whole grain; B, milled grain; C, perisperm; D, cross section of perisperm; E, starch aggregate; F, starch granule. Lipid analysis The lipid in the quinoa fraction was ex- with 10% methanolic HCl and subjected to gas-liquid chroma- tracted with chloroform/methanol/water according to the proce- tography (Shirasaka et al., 1998). dure of Bligh and Dyer (1959). The lipid was transmethylated 82 H. ANDO et al. Results and Discussion no difference among fractions. The proximate composition of Chemical components in each fraction During the milling quinoa grain fractions on the basis of dry weight is shown in of whole quinoa grains, the bran and embryo were separated Table 1. The protein, lipid, sugar, dietary fiber and ash content of from the perisperm portion, and 8.2% bran, 30.1% embryo and whole quinoa grain were 12.9, 6.5, 63.7, 13.9 and 3.0%, respec- 58.8% perisperm were obtained on a grain-weight basis with tively. The milling of the grain had little effect on the content of losses of 2.9%. each component. The protein, lipid, sugar, dietary fiber and ash The moisture content in each fraction was 10.0–11.9% with content of the embryo, however, were 23.5, 10.2, 43.1, 18.9 and 4.3%, respectively. The protein and lipid content were 57% of total protein and 49% of total lipid in whole grain, compared to 39% and 46% in the perisperm. The levels of protein (7.2%), lip- id (5.0%), dietary fiber (8.5%) and ash (1.1%) in the perisperm were considerably lower than in the corresponding whole grain. The sugar content of the perisperm was 78.2%, compared to 63.7% for whole grain. Table 3. Characterization of quinoa starch. Analysis Range X-ray diffraction pattern A-type Gelatinizationa) (˚C) To 54.0±0.6 Tp 62.2±0.3 Tc 71.0±0.7 Enthalpy(⌬H, J/g) 11.0±0.5 Iodine absorption spectrab) ␭max (nm) 602±2.1 Blue value 0.287±0.012 Apparent amylase contentc) (%) 23.9±1.0 ␤-Amylolysis limit (%) 59±1.5 All values are the mean±SD of three separate measuresments. a)To,Tp,and Tc are onset, peak and conclusion temperature, respectively. b)␭max=peak absorbance value over the range of wavelengths examined. Fig. 2. Distribution of particle size of quinoa starch granules. Y axis blue value(BV)=absorbance at 680 nm. shows volume % of starch particles. X axis shows particle size (␮m) with c)Apparent amylose content(%)=[BV(starch)/BV(amylase)]100, assuming logarithmic scale. the amylose BV to be 1.2 (Takeda et al., 1983). Table 1. Proximate composition of quinoa grain fractions. Whole grain Milled grain Bran Perisperm Embryo Proteina) 12.9±0.1 (100) 13.3±0.1 (96) 6.1±0.1 (4) 7.2±0.2 (39) 23.5±0.1 (57) Lipid 6.5±0.2 (100) 6.7±0.2 (95) 3.9±0.1 (5) 5.0±0.2 (46) 10.2±0.2 (49) Sugarb) 63.7 (100) 64.6 (93) 54.2 (7) 78.2 (73) 43.1 (20) Dietary fiber 13.9±0.2 (100) 12.7±0.2 (84) 26.6±0.2 (16) 8.5±0.3 (39) 18.9±0.1 (45) SDFc) 4.3±0.2 (100) 4.4±0.1 (96) 2.1±0.1 (4) 2.2±0.1 (35) 7.5±0.2 (61) IDFd) 9.6±0.3 (100) 8.3±0.2 (79) 24.5±0.2 (21) 6.3±0.2 (41) 11.4±0.1 (38) Ash 3.0±0.1 (100) 2.7±0.1 (76) 9.2±0.2 (24) 1.1±0.1 (25) 4.3±0.2 (51) All values are on a dry basis (%) and are the mean±SD of three separate measurements. The number in parentheses represents the proportion (%) of the content in each fraction against the total content in whole grain. a) N¥6.25. b)Calculated from the difference. c)SDF, soluble dietary fiber. d)IDF, insoluble dietary fiber. Table 2. Mineral content of quinoa grain fractions. Whole grain Milled grain Bran Perisperm Embryo K 825.7±12.3 (100) 639.3±9.4 (71) 2908.5±38.2 (29) 387.9±4.6 (28) 1125.4±18.3 (43) Mg 452.6±13.8 (100) 415.2±12.1 (83) 958.3±17.2 (17) 215.2±10.2 (29) 750.2±11.0 (54) Ca 121.3±5.2 (100) 91.8±3.8 (70) 481.3±11.1 (30) 71.8±2.4 (34) 139.7±7.2 (36) P 359.5±11.3 (100) 360.2±14.2 (92) 350.8±12.2 (8) 286.6±10.5 (50) 482.6±12.8 (42) Fe 9.5±0.2 (100) 9.2±0.1 (87) 14.3±0.2 (13) 7.2±0.1 (48) 11.3±0.3 (39) Mn 3.7±0.5 (100) 3.4±0.2 (81) 10.8±0.6 (19) 2.4±0.3 (38) 5.1±0.7 (43) Cu 0.7±0.1 (100) 0.6±0.1 (81) 1.4±0.2 (19) 0.5±0.1 (44) 0.8±0.1 (37) Zn 0.8±0.1 (100) 0.8±0.1 (91) 0.7±0.1 (9) 0.6±0.1 (48) 1.1±0.2 (43) Na 1.3±0.3 (100) 1.2±0.2 (79) 3.2±0.1 (21) 0.5±0.2 (31) 1.5±0.3 (48) All values (mg/mg%) are the mean±SD of three separate measurements.