全 文 ：园 　　艺 　　学 　　报 32卷
p lasm of egg cell, and the other shaped in lentoid joint to the secondary nucleusmembrane. 20. One sperm nucleus is in the cytop lasm of egg cell,
and the other is fusing with secondary nucleus. 21. One sperm nucleus joint to nucleus membrane of egg just now. 22. Lentoid sperm nucleus
joint to nucleus membrane of egg further. 23. The nuclei of egg and sperm begins to fusion at the site of nuclei membrane fusion, sperm nucleus
is lentoid. Plate Ⅲ: 24 - 27. Chromatin in sperm nucleus relaxes gradually to egg nucleus, and the shape of sperm nucleus changes from lentoid
to flat bit by bit. 28 - 30. The nucleus resulted from karyogamy is spherical, in which male chromatin relaxing can be seen. The other sperm nu2
cleus is fusing with the secondary nucleus, and appearing nucleolus. 31, 32. The chromatin from female or male nucleus can not be distinguished
in zygocyte, male nucleolus appear. A t this time, p rimary endosperm nucleus has divided into two endosperm free nucleis. 33. Two cell p re2em2
bryo. 34, 35. Sperm moves to secondary nucleus. 36. Sperm nucleus on the surface of secondary nucleus. 37, 38. Ellip soidal sperm nucleus
joint to the nucleus membrane of secondary nucleus with different side. Plate Ⅳ: 39. The fusion of nucleus membrane of sperm and egg, and of
sperm and secondary nucleus occurs at the same time, while the chromatin of sperm nuclei relaxes to egg nucleus and secondary nucleus. 40. The
chromatin of sperm nucleus relaxes to secondary nucleus, and male nucleolus begins to appear. 41 - 43. Male nucleolus augments gradually in p ri2
mary endosperm nucleus. 44. Male and female nucleolus is fusing in p rimary endosperm nucleus. 45. M itosis p rophase of p rimary endosperm nu2
cleus, while male and female nucleus havenpit fused in zygocyte. 46. M itosismetaphase of p rimary endosperm nucleus. 47. M itosis anaphase. 48.
M itosis telephase, formed two endosperm free nuclei.
收稿日期 : 2005 - 07 - 29; 修回日期 : 2005 - 09 - 30
基金项目 : 浙江省教育厅资助项目 (20030289) ; 新世纪优秀人才支持计划资助项目
番茄硬度的电子鼻评价与预测的研究
周亦斌 　王 　俊　 (浙江大学生物系统工程与食品科学学院 , 杭州 310029)
F irmness Eva lua tion and Pred iction of Toma to Using Electron ic Nose
Zhou Yibin and Wang Jun (College of B iosystem s Engineering and Food Science, Zhejiang University, Hangzhou 310029, China)
关键词 : 番茄 ; 硬度 ; 电子鼻 ; 评价 ; 预测
中图分类号 : S 64112　　文献标识码 : A　　文章编号 : 05132353X (2005) 0621020201
番茄硬度的评价一般通过有损检测进行。试验采用 (德国 PEN2) 电子鼻信号对番茄 (L ycopersicum esculentum
M ill. ) ‘浙杂 202’硬度进行评价与预测 , 为番茄采收时的成熟度分级提供依据。采果于浙江省农业科学研究院园艺
研究所实验农场。根据外表颜色 , 分为半熟期、成熟期和完熟期。番茄运至实验室后 , 剔除有病和外表有损伤的果
实 , 取 3个熟期质量和大小基本一致的番茄各 20个。
用刺入法在美国产 Instron万能试验机上测量硬度。将番茄果实沿赤道平面切取 7 mm厚的薄片 , 选取番茄果皮内
侧果肉处角度间隔为 120°的 3点作为测量点 , 计算机于此过程中自动采集 , 记录刺入力。刺入探针直径 6 mm, 刺入
果肉深度 3 mm, 刺入速度为 5 mm·s- 1。选取每个番茄 3个刺入点 , 刺入过程中所需最大力的均值计算硬度 , 硬度值
Fi (MPa) =最大力的均值 /探头断面面积。将番茄按硬度分为 3个等级 : Fi > 0195 MPa的为半熟期 , 0138 MPa≥Fi≥
0128 MPa的为成熟期 , Fi < 0128 MPa的为完熟期。
图 1显示了电子鼻对不同成熟度番茄的主成分分析 ( PCA ) 结果 , 前 2个主成分的累计贡献率为 98188%。电子
鼻可以较好地区别番茄的硬度差异。通过偏最小二乘法分析 ( PLS) , 建立电子鼻信号预测硬度的校准模型 , 并采用
完全交叉确认的方式对所建立的模型进行检验 , 图 2显示检验结果 , 用此模型预测的硬度与实际硬度之间的相关性为
01936, 预测标准误差 ( SEP) 为 01147 MPa。
图 1　不同成熟度番茄 (结合硬度指标划分 ) 的 PCA分析
F ig. 1　PCA score plot of toma toes a t d ifferen t ma ture
stages accord ing to f irmness
图 2　番茄硬度的 PL S分析图
F ig. 2　Pred icted f irmness ( PL S m odel ba sed on E2nose
m ea surem en ts) vs. m ea sured f irmness of toma toes
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