Please wait a minute...
浙江大学学报(农业与生命科学版)  2021, Vol. 47 Issue (6): 736-742    DOI: 10.3785/j.issn.1008-9209.2021.05.281
研究论文     
不同杨梅品种果实游离氨基酸组成分析
朱奕凡1(),王妍1,汪国云2,周超超2,焦云3,甘可欣1,孙德利4,朱长青1,贾惠娟1,高中山1()
1.浙江大学农业与生物技术学院,杭州 310058
2.余姚市农业技术推广服务总站,浙江 宁波 315400
3.宁波市农业科学院林业研究所,浙江 宁波 315000
4.浙江大学农业试验站,杭州 310058
Analysis of free amino acid composition in fruits of different bayberry (Morella rubra) varieties
Yifan ZHU1(),Yan WANG1,Guoyun WANG2,Chaochao ZHOU2,Yun JIAO3,Kexin GAN1,Deli SUN4,Changqing ZHU1,Huijuan JIA1,Zhongshan GAO1()
1.College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, China
2.Yuyao Agricultural Technology Extension Service Station, Ningbo 315400, Zhejiang, China
3.Forestry Research Institute, Ningbo Academy of Agricultural Sciences, Ningbo 315000, Zhejiang, China
4.Agricultural Experiment Station, Zhejiang University, Hangzhou 310058, China
 全文: PDF(917 KB)   HTML
摘要:

果实中的游离氨基酸对果实风味品质和营养价值有重要影响。为研究不同杨梅品种果实中游离氨基酸组分和含量的差异,以浙江省余姚市的11个杨梅栽培品种以及选育优系为主要试验材料,采用日立L-8900型全自动氨基酸分析仪对杨梅果实中的游离氨基酸组分进行定量分析。结果表明:11个杨梅品种均含有17种常见游离氨基酸和1种特殊的γ-氨基丁酸,且总游离氨基酸质量浓度为338.25~827.34 μg/mL,表明不同色泽的杨梅品种间游离氨基酸含量存在较大差异。紫黑色和红色的杨梅作为市场上的主栽品种,如‘荸荠’和‘东魁’,其总游离氨基酸量比粉红色和水晶杨梅的氨基酸含量更高。γ-氨基丁酸在杨梅果实中含量丰富,在67.05~156.32 μg/mL之间,且不同品种间也存在较大差异,说明不同杨梅品种果实在氨基酸营养品质上有所差异。本研究对于优良风味杨梅品种选育有重要参考意义。

关键词: 杨梅游离氨基酸γ-氨基丁酸营养品质    
Abstract:

Free amino acids have an impact on the flavor and nutritional values of fresh fruits. The variation of free amino acid compositions and contents in the fruits of 11 different bayberry varieties from Yuyao City, Zhejiang Province, were investigated by Hitachi L-8900 automatic amino acid analyzer. The results showed that the 11 bayberry varieties all contained 17 common free amino acids and one special amino acid γ-aminobutyric acid, and the total contents of free amino acids in the fruits ranged from 338.25 to 827.34 μg/mL. The variations in free amino acid contents among different colored fruits of the bayberry varieties were big. The purple-black and red bayberries, such as ‘Biqi’ and ‘Dongkui’, were the main varieties on the market with the total contents of free amino acids being higher than those of pink and milky white bayberries. The γ-aminobutyric acid content was rich in the 11 bayberry varieties, and its content ranged from 67.05 to 156.32 μg/mL. But there were some differences between different varieties, which indicating that bayberry varieties have differences in nutrition and quality. These results are useful for evaluating the effects of amino acids on fruit flavor and can provide references to the new variety development.

Key words: bayberry    free amino acid    γ-aminobutyric acid    nutrition and quality
收稿日期: 2021-05-28 出版日期: 2021-12-25
CLC:  S 667.6  
基金资助: 浙江省宁波市重大科技项目(2021Z008);国家自然科学基金(31972346)
通讯作者: 高中山     E-mail: 934630852@qq.com;gaozhongshan@zju.edu.cn
作者简介: 朱奕凡(https://orcid.org/0000-0001-7676-0709),E-mail:934630852@qq.com
服务  
把本文推荐给朋友
加入引用管理器
E-mail Alert
RSS
作者相关文章  
朱奕凡
王妍
汪国云
周超超
焦云
甘可欣
孙德利
朱长青
贾惠娟
高中山

引用本文:

朱奕凡,王妍,汪国云,周超超,焦云,甘可欣,孙德利,朱长青,贾惠娟,高中山. 不同杨梅品种果实游离氨基酸组成分析[J]. 浙江大学学报(农业与生命科学版), 2021, 47(6): 736-742.

Yifan ZHU,Yan WANG,Guoyun WANG,Chaochao ZHOU,Yun JIAO,Kexin GAN,Deli SUN,Changqing ZHU,Huijuan JIA,Zhongshan GAO. Analysis of free amino acid composition in fruits of different bayberry (Morella rubra) varieties. Journal of Zhejiang University (Agriculture and Life Sciences), 2021, 47(6): 736-742.

链接本文:

http://www.zjujournals.com/agr/CN/10.3785/j.issn.1008-9209.2021.05.281        http://www.zjujournals.com/agr/CN/Y2021/V47/I6/736

氨基酸

Amino acid

紫黑色杨梅 Purple-black bayberry红色杨梅 Red bayberry粉红色杨梅 Pink bayberry水晶杨梅 Milky white bayberry

‘荸荠’

‘Biqi’

‘月粒盘’

‘Yuelipan’

‘2015-4’‘Y2012-136’

‘东魁’

‘Dongkui’

‘水梅’

‘Shuimei’

‘Y2010-70’

‘夏至红’

‘Xiazhihong’

‘Y2012-138’‘Y2012-145’‘Y2012-148’
天冬氨酸 Asp56.20±0.42b58.08±4.00b60.35±4.65b72.11±4.51a33.05±1.27c67.02±1.40b37.75±1.49c34.69±1.41c27.45±2.12cd16.94±1.85d25.74±1.62cd
苏氨酸 Thr253.83±1.57a221.47±6.81a203.65±6.75ab248.41±8.34a81.35±1.52cd259.94±4.80a273.32±3.39a45.97±1.47cd126.30±7.38bc18.05±1.10e38.45±1.88cd
丝氨酸 Ser61.11±0.60bc57.89±4.30bc45.34±2.73bcd129.49±6.85a53.48±0.97bcd89.80±3.28b73.58±2.13b14.31±0.53d30.20±2.08bcd11.69±0.66d22.34±1.14cd
谷氨酸 Glu100.11±0.67ab121.61±3.91a104.73±5.12a99.66±4.06ab73.81±1.54c119.97±4.34a106.60±3.51a70.81±3.24c85.87±1.99bc46.84±1.23d54.21±2.04d
甘氨酸 Gly2.87±0.13ab2.26±0.08bc2.31±0.56bc3.25±0.31a2.68±0.10ab2.08±0.23bc2.15±0.40bc1.51±0.16cd1.17±0.06d2.39±0.09b2.50±0.17ab
丙氨酸 Ala42.34±0.32b39.72±1.81b21.81±2.88cde70.18±0.82a65.16±0.66a93.49±2.93a30.31±2.79cd10.74±0.36e32.17±2.95bc16.37±1.18e20.48±0.06de
半胱氨酸 Cys0.97±0.72f1.25±0.50f6.84±1.15bc1.65±1.05ef4.86±0.36bcd15.23±0.61a10.21±1.95a1.99±0.84def7.94±2.06ab1.24±0.89f4.73±1.87cde
缬氨酸 Val6.22±0.24c9.61±0.97b8.78±1.51b8.62±1.03b7.53±0.58bc12.16±0.90a11.60±1.37a7.32±0.63bc8.94±1.66b7.25±1.85bc7.11±0.26bc
蛋氨酸 Met0.29±0.35a0.71±0.23ab0.79±1.34a0.69±0.43a1.02±0.89a1.13±0.51ab2.73±0.83a2.24±0.43a1.27±0.05a1.38±0.21a1.87±1.62a
异亮氨酸 Ile1.91±0.51c3.75±1.26abc3.59±1.52abc2.81±0.34bc4.58±1.20abc6.98±0.16a6.33±0.43a4.27±0.14abc5.44±1.92ab3.73±0.97abc4.12±0.60abc
亮氨酸 Leu3.10±0.11c4.17±1.66c4.14±1.28c3.30±0.31c5.10±0.91bc8.20±0.41a6.96±1.11ab3.24±0.20c8.88±0.40a4.11±0.89c3.31±0.26c
酪氨酸 Tyr6.12±0.66cd6.29±1.40cd10.12±1.40b3.95±1.27d9.88±1.04b9.44±0.20b7.22±0.46c6.38±0.30cd14.77±1.37a7.29±0.65c6.85±0.67c
苯丙氨酸 Phe9.01±0.15a6.13±0.76bc3.58±0.69d5.44±0.65cd6.74±0.30bc3.62±0.44d5.43±0.94cd6.05±0.21c5.54±1.09c7.26±0.19abc8.19±1.30ab
赖氨酸 Lys16.08±0.09a22.54±0.91a7.15±2.28d10.51±0.88bcd8.27±0.27cd11.63±1.61bc18.48±1.29a11.36±1.55bc10.32±1.63bcd12.29±0.65b9.93±1.80bcd
组氨酸 His30.83±0.67a23.81±2.11b12.73±1.82b13.91±1.34b6.08±0.02c14.38±1.13b18.37±1.19b3.63±0.80c17.88±1.68b5.19±0.98c3.80±1.77c
精氨酸 Arg7.36±0.18cd10.80±1.68c20.62±0.78b21.37±2.35b32.86±0.81a34.59±1.17a12.01±1.58c6.12±1.23cd22.77±1.70b2.70±0.89d6.36±1.26cd
脯氨酸 Pro64.48±1.13cd32.86±2.32de19.28±1.32de6.57±1.52e202.47±2.57a10.63±0.33e78.07±1.27bc125.00±2.51b50.19±1.33cde80.04±1.96bc127.66±3.56b
gABA109.83±1.44bc94.98±3.20cd77.35±16.05de116.10±14.77b90.29±1.30cd67.05±8.42e91.61±14.64cd104.48±9.50bcd75.08±16.17de93.48±18.89cd156.32±18.33a
TFAA772.66ab717.95ab613.15bcd818.03a689.21abc827.34a792.73a460.12de532.15cd338.25e503.98de
EAA290.44a268.38a231.68ab279.79a114.58cd303.66a324.84a80.45cd166.68bc54.08d72.99cd
NEAA372.39bc354.59bc304.12c422.14ab484.33a456.63a376.26bc275.19cd290.40cd190.69d274.67cd
CEAA328.63a302.99a265.03ab315.07ab153.52cd352.63a355.23a90.20d207.33bc61.97d83.15d
MAA201.13abc232.59a213.78ab220.28a173.41cd257.68a199.33abc142.40de178.02bcd101.20f118.96ef
EAA/TFAA/%37.5837.3837.7934.2016.6236.7040.9817.4831.3215.9914.48
MAA/TFAA/%26.0332.4034.8726.9226.9231.1525.1430.5133.4529.9223.60
EAA/NEAA/%77.9975.6976.1866.2823.6666.5086.3329.2457.4028.3626.57
表1  不同杨梅品种果实中常见游离氨基酸组分含量 (μg/mL)
图1  不同杨梅品种果实呈味氨基酸含量短栅上不同小写字母表示在P<0.05水平差异有统计学意义。
1 LIU L X, JIN X J, CHEN N, et al. Phylogeny of Morella rubra and its relatives (Myricaceae) and genetic resources of Chinese bayberry using RAD sequencing. PLoS ONE, 2015,10(10):e0139840. DOI:10.1371/journal.pone.0139840
doi: 10.1371/journal.pone.0139840
2 HUGUET V, GOUY M, NORMAND P, et al. Molecular phylogeny of Myricaceae: a reexamination of host-symbiont specificity. Molecular Phylogenetics and Evolution, 2005,34(3):557-568. DOI:10.1016/j.ympev.2004.11.018
doi: 10.1016/j.ympev.2004.11.018
3 BAO J S, CAI Y Z, SUN M, et al. Anthocyanins, flavonols, and free radical scavenging activity of Chinese bayberry (Myrica rubra) extracts and their color properties and stability. Journal of Agricultural and Food Chemistry, 2005,53(6):2327-2332. DOI:10.1021/jf048312z
doi: 10.1021/jf048312z
4 MANDRIOLI R, MERCOLINI L, RAGGI M A. Recent trends in the analysis of amino acids in fruits and derived foodstuffs. Analytical and Bioanalytical Chemistry, 2013,405(25):7941-7956. DOI:10.1007/s00216-013-7025-8
doi: 10.1007/s00216-013-7025-8
5 蒋滢,徐颖,朱庚伯.人类味觉与氨基酸味道.氨基酸和生物资源,2002,24(4):70. DOI:10.3969/j.issn.1006-8376.2002.04.023
JIANG Y, XU Y, ZHU G B. Human taste and amino acid taste. Amino Acids & Biotic Resources, 2002,24(4):70. (in Chinese)
doi: 10.3969/j.issn.1006-8376.2002.04.023
6 孙嘉卿,冯涛,宋诗清,等.果蔬风味物质形成的生物化学基础.中国果菜,2020,40(6):10-15. DOI:10.19590/j.cnki.1008-1038.2020.06.002
SUN J Q, FENG T, SONG S Q, et al. Biochemical basis for the formation of flavor substances in fruits and vegetables. China Fruit & Vegetable, 2020,40(6):10-15. (in Chinese with English abstract)
doi: 10.19590/j.cnki.1008-1038.2020.06.002
7 陈华峰,唐玉情,潘亚婕,等.果实风味的代谢基础及其调控机制研究进展.植物研究,2021,41(3):474-480. DOI:10.7525/j.issn.1673-5102.2021.03.019
CHEN H F, TANG Y Q, PAN Y J, et al. Progress on the metabolic basis and regulation mechanism of fruit flavor. Bulletin of Botanical Research, 2021,41(3):474-480. (in Chinese with English abstract)
doi: 10.7525/j.issn.1673-5102.2021.03.019
8 蒋滢.氨基酸应用.北京:世界图书出版公司,1996.
JIANG Y. Amino Acid Applications. Beijing: World Book Publishing Company, 1996. (in Chinese)
9 张丽梅,陈菁瑛,黄玉吉,等.山药品种间氨基酸含量的差异性研究.氨基酸和生物资源,2008,30(2):12-15. DOI:10.3969/j.issn.1006-8376.2008.02.004
ZHANG L M, CHEN J Y, HUANG Y J, et al. Research on the difference of amino acid contents among Chinese yam varieties. Amino Acids & Biotic Resources, 2008,30(2):12-15. (in Chinese with English abstract)
doi: 10.3969/j.issn.1006-8376.2008.02.004
10 黄勇其,陈龙珠.贵州五种南沙参药材中氨基酸含量的比较.中国药业,2002,11(4):62. DOI:10.3969/j.issn.1006-4931.2002.04.043
HUANG Y Q, CHEN L Z. Comparison of amino acid contents in five species of Radix adenophorae in Guizhou. China Pharmaceuticals, 2002,11(4):62. (in Chinese )
doi: 10.3969/j.issn.1006-4931.2002.04.043
11 张海峰,叶新福.早稻氨基酸含量分析.中国农学通报,2006,22(12):175-177. DOI:10.3969/j.issn.1000-6850.2006.12.040
ZHANG H F, YE X F. Content analysis of amino acid among early rice. Chinese Agricultural Science Bulletin, 2006,22(12):175-177. (in Chinese with English abstract)
doi: 10.3969/j.issn.1000-6850.2006.12.040
12 钟惠民,袁瑾,辛宝玲,等.黄山药中氨基酸及营养成分.氨基酸和生物资源,2002,24(4):15-16. DOI:10.3969/j.issn.1006-8376.2002.04.005
ZHONG H M, YUAN J, XIN B L, et al. Analyses of amino acid and nutrition of D. panthaica Prain et Burk. Amino Acids & Biotic Resources, 2002,24(4):15-16. (in Chinese with English abstract)
doi: 10.3969/j.issn.1006-8376.2002.04.005
13 张辉,徐满英.γ-氨基丁酸作用的研究进展.哈尔滨医科大学学报,2006,6(3):267-269. DOI:10.3969/j.issn.1000-1905.2006.03.030
ZHANG H, XU M Y. Research progress on the effect of γ-aminobutyric acid. Journal of Harbin Medical University, 2006,6(3):267-269. (in Chinese )
doi: 10.3969/j.issn.1000-1905.2006.03.030
14 HSU Y T, CHANG Y G, CHANG C P, et al. Altered behavioral responses to gamma-aminobutyric acid pharma-cological agents in a mouse model of Huntington’s disease. Movement Disorders, 2017,32(11):1600-1609. DOI:10.1002/mds.27107
doi: 10.1002/mds.27107
15 郭哓娜,朱永义,朱科学.生物体内γ-氨基丁酸的研究.氨基酸和生物资源,2003,25(2):70-72.
GUO X N, ZHU Y Y, ZHU K X. Study on GABA in organism. Amino Acids & Biotic Resources, 2003,25(2):70-72. (in Chinese with English abstract)
16 林智,大森正司.γ-氨基丁酸茶(Gabaron Tea)降血压机理的研究.茶叶科学,200l,21(2):153-156.
LIN Z, MASASHI O. Study on the functional mechanism of Gabaron Tea on hypertension. Journal of Tea Science, 200l,21(2):153-156. (in Chinese with English abstract)
17 KAWAKAMI K, YAMADA K, YAMADA T, et al. Antihypertensive effect of γ-aminobutyric acid-enriched brown rice on spontaneously hypertensive rats. Journal of Nutritional Science Vitarminology, 2018,12(1):56-62. DOI:10.3177/jnsv.64.56
doi: 10.3177/jnsv.64.56
18 CHEN S, TAN B, XIA Y Y, et al. Effect of dietary gamma-aminobutyric acid supplementation on the intestinal functions in weaning piglets. Food & Function, 2019,10(4):366-378. DOI:10.1039/c8fo02161a
doi: 10.1039/c8fo02161a
19 黄艳.常见果蔬中游离氨基酸含量的测定.安徽农业科学,2013,41(9):4088-4089. DOI:10.13989/j.cnki.0517-6611.2013.09.036
HUANG Y. Determination of free amino acids in common fruits and vegetables. Journal of Anhui Agricultural Sciences, 2013,41(9):4088-4089. (in Chinese with English abstract)
doi: 10.13989/j.cnki.0517-6611.2013.09.036
20 戴宏芬,赖志勇,黄炳雄,等.反相HPLC法测定杨梅和黄皮果肉中的氨基酸.仲恺农业技术学院学报,2008,21(3):7-11. DOI:10.3969/j.issn.1674-5663.2008.03.002
DAI H F, LAI Z Y, HUANG B X, et al. Determination of amino acids in flesh of waxberry and wampee by RP-HPLC. Journal of Zhongkai University of Agriculture and Technology, 2008,21(3):7-11. (in Chinese with English abstract)
doi: 10.3969/j.issn.1674-5663.2008.03.002
21 张泽煌,钟秋珍,林旗华,等.3个杨梅品种果实发育过程中氨基酸含量变化.热带作物学报,2011,32(12):2240-2245. DOI:10.3969/j.issn.1000-2561.2011.12.008
ZHANG Z H, ZHONG Q Z, LIN Q H, et al. Changes of amino acids content during the fruits development of three bayberry cultivars. Chinese Journal of Tropical Crops, 2011,32(12):2240-2245. (in Chinese with English abstract)
doi: 10.3969/j.issn.1000-2561.2011.12.008
22 张泽煌,卢新坤,林旗华,等.10个杨梅品种果实糖和氨基酸含量分析.江西农业学报,2011,23(7):18-20. DOI:10.19386/j.cnki.jxnyxb.2011.07.005
ZHANG Z H, LU X K, LIN Q H, et al. Analysis on content of sugar and amino acid in fruits of 10 waxberry cultivars. Acta Agriculturae Jiangxi, 2011,23(7):18-20. (in Chinese with English abstract)
doi: 10.19386/j.cnki.jxnyxb.2011.07.005
23 PRIPIS-NICOLAU L, BERTRAND A, MAUJRAN A, et al. Formation of flavor components by the reaction of amino acid and carbonyl compounds in mild conditions. Journal of Agricultural and Food Chemistry, 2000,48(9):376l-3766. DOI:10.1021/jf991024w
doi: 10.1021/jf991024w
24 李正丽,陈守智,张自翔,等.云南野生大树杨梅果实营养成分分析.云南农业大学学报,2006,21(4):541-544. DOI:10.16211/j.issn.1004-390x(n).2006.04.031
LI Z L, CHEN S Z, ZHANG Z X, et al. Study on uncultivated waxberry of Yunnan nutritive compositions. Journal of Yunnan Agricultural University, 2006,21(4):541-544. (in Chinese with English abstract)
doi: 10.16211/j.issn.1004-390x(n).2006.04.031
25 徐国能.杨梅品种果汁加工特性研究.杭州:浙江大学,2007:18-20. DOI:10.1002/psb.v18:20
XU G N. Studies on juice processing characteristics of bayberry varieties. Hangzhou: Zhejiang University, 2007:18-20. (in Chinese with English abstract)
doi: 10.1002/psb.v18:20
[1] 王慧茹,闫思华,高艳明,李建设. 不同整枝方式对樱桃番茄果实商品性、营养品质及产量的影响[J]. 浙江大学学报(农业与生命科学版), 2021, 47(3): 347-353.
[2] 王天玉,林媚,姚周麟,王鹏,平新亮,方华. 乙基多杀菌素在杨梅果实和土壤中的残留消解特征及其安全性评价[J]. 浙江大学学报(农业与生命科学版), 2021, 47(1): 43-51.
[3] 陈方永,胡丹,颜帮国,倪海枝,王引. ‘永泰’杨梅亲本鉴定及其单核苷酸多态性遗传变异分析[J]. 浙江大学学报(农业与生命科学版), 2020, 46(6): 708-717.
[4] 张亚芬,杨晖. 不同光源处理对栀子叶片叶绿素荧光参数和生化成分的影响[J]. 浙江大学学报(农业与生命科学版), 2020, 46(4): 441-448.
[5] 向洁, 王富强, 郭宝光, 王庆刚, 余成群, 沈振西, 邵小明. 西藏河谷区燕麦与箭筈豌豆混间作对产量和营养品质的影响[J]. 浙江大学学报(农业与生命科学版), 2018, 44(5): 555-564.
[6] 陈珊珊, 周业凯, 张志明, 张敏, 汪俏梅. 二氧化碳施肥对樱桃番茄果实发育和品质的影响[J]. 浙江大学学报(农业与生命科学版), 2018, 44(3): 318-326.
[7] 丁文雅, 林若筠, 周伟伟, 周恺, 林咸永. 不同供氮水平下雾培与水培生菜生长和营养品质差异的比较[J]. 浙江大学学报(农业与生命科学版), 2016, 42(6): 703-712.
[8] 陈方永1,2*, 倪海枝1, 王引1, 任正初1, 刘继红2, 王一光3. 多效唑对杨梅枯枝病的影响及防治[J]. 浙江大学学报(农业与生命科学版), 2014, 40(6): 653-660.
[9] 王军君1, 邬小撑2, 丁文雅1, 周元清1, 林咸永1*. 雾培营养液氮钾水平对不同番茄品种果实产量和营养品质的影响[J]. 浙江大学学报(农业与生命科学版), 2013, 39(5): 489-496.
[10] 周防震, 张晓元, 孙奋勇, 郭勇. 二氢杨梅素诱导MDA-MB-231细胞凋亡[J]. 浙江大学学报(农业与生命科学版), 2012, 38(3): 293-298.
[11] 丁文雅,邬小撑,刘敏娜,王军君,林咸永. 不同营养液配方对雾培生菜生物量和营养品质的影响[J]. 浙江大学学报(农业与生命科学版), 2012, 38(2): 175-184.
[12] 董兰学, 吴良欢, 王秋灵, 陈洪利. 不同抗冻模式对高山杨梅养分含量和果实品质的影响[J]. 浙江大学学报(农业与生命科学版), 2011, 37(6): 655-662.
[13] 吕倩1,吴良欢1,徐建龙2,寿惠霞3,杨肖娥1;. 叶面喷施氨基酸铁肥对稻米铁含量和营养品质的影响[J]. 浙江大学学报(农业与生命科学版), 2010, 36(5): 528-534.
[14] 陈健初  叶兴乾  席玙芳. 抗坏血酸对杨梅花色苷色素稳定性的影响[J]. 浙江大学学报(农业与生命科学版), 2005, 31(3): 298-300.
[15] 陈健初  夏其乐  潘向荣  徐斐燕. 杨梅果汁的抗氧化特性研究[J]. 浙江大学学报(农业与生命科学版), 2004, 30(6): 657-661.