宁夏枸杞果皮蜡质微形态及蜡质组分研究

Study on Wax Micro-morphology and Wax Components in the Pericarp of Ningxia Wolfberry

果实制干是宁夏枸杞炮制的主要过程,宁夏枸杞不同品种在制干特性方面存在一定的差异。该研究以宁夏枸杞栽培中制干差异较大的品种‘宁杞1号’(易制干)和‘宁杞5号’(不易制干)果实为材料,采用扫描电镜技术和GC-MS技术对2个宁夏枸杞品种不同发育时期(青果期、色变期、成熟期)的果实果皮结构以及果皮蜡质微形态、含量和组分进行了观测,从果皮蜡质微形态及组分的积累变化初步揭示枸杞果皮蜡质的积累规律,以明确不同枸杞品种果皮蜡质组分差异,为不同品种适宜促干剂的筛选以及促干剂的合理使用提供理论依据。结果表明:(1)‘宁杞1号’和‘宁杞5号’枸杞表皮细胞外侧细胞壁均呈现脊状突起的结构,在果实青果期脊状突起不连续,脊和脊之间排列紧密;随着发育时期的延后,脊状突起的连续性逐渐增强,且脊与脊之间的间距逐渐变宽,蜡质呈膜状覆盖于凸起的脊和两脊之间的沟内。(2)‘宁杞1号’和‘宁杞5号’两个枸杞品种在果实发育过程中,果皮单位面积蜡质含量均呈先下降后上升的趋势,在成熟期单位面积蜡质含量最高,且‘宁杞1号’3个发育时期果皮单位面积蜡质含量均高于同期‘宁杞5号’,呈现出与扫描电镜观察到的蜡质分布基本一致的变化趋势。(3)2个品种3个时期的果实表皮蜡质组分均由烷烃类、酮类、醇类、酸类、醛类、酯类和碘代烷烃类组成,两品种青果期和色变期果皮蜡质组分相同,主要由烷烃类、醇类和碘代烷烃类组成,它们成熟期的果皮蜡质组分主要由烷烃类、醇类和酯类组成。(4)主成分分析结果显示,3个生育时期‘宁杞5号’果皮蜡质组分多为烷烃类物质,较‘宁杞1号’更利于阻挡果实水分的散失。研究发现,影响枸杞果实制干的原因在于枸杞果皮蜡质含量、结构和蜡质组分,烷烃类组分能够有效阻止果实体内水分的散失,‘宁杞5号’果皮蜡质中烷烃组分含量更高,果皮保水性更强,致果实不易制干。

Fruit drying is the main processing process of Lycium barbarum in Ningxia,and there are certain differences in the drying characteristics of different varieties of L.barbarum.Taking the fruits of‘Ningqi No.1’(easy to dry)and‘Ningqi No.5’(not easy to dry)with large differences in the cultivation of wolfberries in Ningxia,we used scanning electron microscopy technology and GC-MS technology to observe the structure of the peel of the two varieties at different development stages(green fruit stage,color deformation stage,maturity stage)and the waxy microform,content and composition of the peel wax,and the accumulation law of wolfberry waxy skin was initially revealed from the accumulation changes of the waxy microform and components of the peel,clarify the differences in waxy composition of the peel of different wolfberry varieties,and provide a theoretical basis for the screening of suitable drying agents of different varieties and the rational use of drying agents.The results showed that:(1)the outer cell wall of the epidermal cells of‘Ningqi No.1’and‘Ningqi No.5’of wolfberry showed the structure of ridge-like protrusions,which were discontinuous in the green fruit stage,and the ridges and ridges were closely arranged;with the delay of the development period,the continuity of the ridge-like protrusions gradually increased,and the spacing between the ridges and the ridges gradually widened,and the wax covers the raised ridges and the grooves between the two ridges in a membranous manner.(2)In the process of fruit development,the wax content per unit area of the peel showed a trend of first decreasing and then increasing,and the wax content per unit area of the fruit reached the highest in the mature stage,and the wax content per unit area of the three developmental periods of‘Ningqi No.1’was higher than that of‘Ningqi No.5’in the same period,showing a trend of change that was basically consistent with the wax distribution observed by scanning electron microscopy.(3)The waxy components of the fruit epidermis of the two varieties in the three periods are composed of alkanes,ketones,alcohols,acids,aldehydes,esters and iodoalkanes,and the waxy components of the peels of the two varieties are the same at the green fruit stage and the color stage,mainly composed of alkanes,alcohols and iodoalkanes,and the waxy components of the peels at the ripe stage are mainly composed of alkanes,alcohols and esters.(4)The results of principal component analysis show that the waxy components of the peel of‘Ningqi No.5’in the three growth periods are mostly alkanes,which are more conducive to blocking the loss of fruit water than‘Ningqi No.1’.The study found that the reason for the impact on the dried fruit of wolfberries is the wax content,structure and waxy composition of the peel.The alkane components can effectively prevent the loss of water in the fruit body,and the alkane components in the waxy skin of‘Ningqi No.5’are higher,the peel is more water-retaining,and the fruit is not easy to dry.