Structural investigations on betacyanin pigments by LC NMR and 2D NMR spectroscopy

Four betacyanin pigments were analysed by LC NMR and subjected to extensive NMR characterisation after isolation. Previously, low pH values were applied for NMR investigations of betalains resulting in rapid degradation of the purified substances thus preventing extensive NMR studies. Consequently, up to now only one single (13)C NMR spectrum of a betalain pigment, namely that of neobetanin (=14,15-dehydrobetanin), was available. Because of its sufficient stability under highly acidic conditions otherwise detrimental for betacyanins, this pigment remained an exemption. Since betalains are most stable in the pH range of 5-7, a new solvent system has been developed allowing improved data acquisition through improved pigment stability at near neutral pH. Thus, not only (1)H, but for the first time also partial (13)C data of betanin, isobetanin, phyllocactin and hylocerenin isolated from red-purple pitaya [Hylocereus polyrhizus (Weber) Britton & Rose, Cactaceae] could be indirectly obtained by gHSQC- and gHMQC-NMR experiments.     

人工授粉对火龙果果实发育的影响

于开花期对红皮红肉类型火龙果进行人工授粉与自然授粉处理,并对不同发育阶段的子房或果实进行解剖观察,以研究人工授粉对果实发育的影响.结果表明:人工授粉可提高火龙果的平均单果重和商品果率,平均单果重与果实内种子数呈显著正相关关系;火龙果子房为多胚珠结构,子房内有若干“珠柄-胚珠”单元,胚珠在开花后发育成种子,珠柄则发育成肉...     

火龙果果皮中可溶性膳食纤维的提取方法

火龙果(Hylocereus undulatus)果皮可以作为一种优良的膳食纤维来源,且其膳食纤维具有良好的理化性能。为提高火龙果果皮的综合利用水平,该研究以火龙果果皮为原料,首先采用纤维素酶水解法对火龙果果皮中的可溶性膳食纤维进行提取,然后采用单因素试验和响应面法优化酶提取工艺。结果表明,纤维素酶法提取火龙果果皮中可溶性膳食纤维的优化工艺条件为:纤维素酶浓度0.54%,酶解温度50°C,pH5.2。在此条件下,可溶性膳食纤维的提取率可达19.81%;膳食纤维的持水力为31.25 g·g~(–1),溶胀性为29.11 m L·g~(–1)。     

火龙果果皮红色素的微波提取工艺及其应用

以火龙果果皮干粉为原料,就微波提取火龙果果皮红色素的工艺进行研究。结果表明,果皮红色素的最大吸收峰波长是535 nm,溶液呈鲜红色;微波提取火龙果果皮红色素的最优条件为:以50%乙醇为浸提剂,微波功率为180 W,提取时间为60 s,最佳料液比为1∶60 g/mL。微波提取火龙果色素的效果明显优于常规的溶剂浸提法。当火龙果果皮红色素粗提物含量在40 mg/100 g果冻时,果冻的感官评分最高。当色素含量为23 mg/100 mL时,制作出来的调和酒与购买的调和酒颜色接近,呈粉色。应用在果冻及调和酒里的火龙果果皮红色素都在无避光室温放置一个月后颜色消失。维生素C对于火龙果果皮红色素有防降解作用。该色素应低温避光保存。