UPLC-MS/MS分析牛肉红朱橘果皮发育期类黄酮组分特征

利用超高效液相色谱串联质谱仪(UPLC-MS/MS)和代谢组学方法检测、分析牛肉红朱橘果皮生长发育期5个不同阶段类黄酮动态积累特征.结果表明:整个生长发育期内共检测到206种物质(包含黄酮、黄烷酮、黄酮醇等);生长发育期不同阶段类黄酮组分和丰度存在显著差异,大部分类黄酮含量随着果实逐渐成熟呈下降趋势,仅少部分物质如根皮素、根皮苷、槲皮素-7-O-葡萄糖苷等呈上升趋势.     

不同干燥方式对芒果果皮理化特性的影响

采用热风干燥、远红外干燥和微波干燥处理芒果果皮,探讨不同干燥方法对芒果果皮理化特性的影响.结果表明:微波干燥的芒果果皮干基含水率下降程度和干燥速率都优于热风干燥和远红外干燥,但复水性较差;3种干燥方法对果皮色泽及总多酚、总黄酮和色素含量的影响各有差异.通过对干燥芒果果皮收缩率、复水性、色泽及总多酚、总黄酮和色素含量进行主成分分析,得出远红外干燥的主成分综合得分最高,此干燥方法更加适合用于干燥芒果果皮.     

Sucrose synthase dominates carbohydrate metabolism and relative growth rate in growing kiwifruit (Actinidia deliciosa, cv Hayward)

Changes in fruit growth rate, carbohydrate content (glucose, fructose, sucrose and starch) and enzyme activity (sucrose synthase, UDPglucose pyrophosphorylase, fructokinase, glucokinase, sucrose phosphate synthase, ADPglucose pyrophosphorylase and invertases), in the external pericarp of kiwifruit, were measured throughout the growing season. Sucrose synthase showed the highest activity among the sucrose cleaving enzymes during large part of the growing season. The activity of invertases were much lower than that of sucrose synthase until ripening started. Sucrose synthase showed a tight although not linear relationship with the fruit RGR. Furthermore, sucrose synthase showed linear and significant correlations with the activities of both fructokinase and UDPglucose pyrophosphorylase indicating a strong co-regulation of the activities of these three enzymes involved in sucrose cleavage and sink strength, in kiwifruit. Sucrose synthase is suggested to be the dominating enzyme in the cleavage of imported carbon in kiwifruit, in tight coordination with fructokinase and UDPglucose pyrophosphorylase.     

Phenolic compounds and the antioxidant activities in litchi pericarp: Difference among cultivars

The pericarps of 10 litchi cultivars from two production seasons were studied for their phenolic concentrations and composition and activities of anti-oxidation. The total phenolic concentrations in dried litchi pericarp ranged from 51 to 102 g k g⁻¹. Different cultivars varied considerably in phenolic concentration and composition. Cultivars ‘Nuomici’ exhibited significantly higher concentrations of proanthocyanidins, flavonoids, phenolic acids and therefore total soluble phenolics than the other cultivars, while ‘Lanzhu’ and ‘Guiwei’ had minor values in phenolics. The extracts of litchi pericarp exhibited considerably high ferric reducing antioxidant power (FRAP) and strong activities of 1,1-diphenyl-2-picryhydrazyl (DPPH) scavenging, lipid peroxidation inhibiting, and oxidative DNA damage protection. The crude ethanol extracts of pericarp displayed significantly higher FRAP and stronger DPPH scavenging capacity than butylated hydroxylytoluene (BHT) and catechin. Among the tested cultivars, concentrations of major phenolics had significant linear correlations with FRAP and DPPH scavenging activities. These results indicated that litchi pericarp is rich in natural antioxidant phenolic compounds and different litchi cultivars differed considerably in phenolic concentration and antioxidant activities.     

超甜玉米籽粒果皮厚度及灌浆特性研究

对4个不同超甜玉米品种籽粒果皮厚度及灌浆特性进行了分析。结果表明，不同品种和不同授粉天数的果皮厚度差异明显；同一品种籽粒内不同部位间的果皮厚度也有较大差异，这种差异在灌浆前期更为明显，主要表现为胚背面的果皮较胚面薄，之后这种差异逐渐缩小。灌浆期间，籽粒体积和鲜质量变化呈Logistic曲线，相应的拐点分别是授粉后12.1和12.7d；籽粒含水量直线下降，干物质则直线上升。     

氧化还原物质对荔枝果皮花色素苷稳定性的影响

探讨了氧化剂和还原剂对离体荔枝果皮色素苷颜色及稳定性的影响，结果表明：氧化剂可显著促进荔枝果皮花色素苷的降解，花色素苷由红色迅速变为褐色，当pH值升高时，这种作用更显，还原剂不能抵消氧化剂的破坏作用，反而促进花色素苷的降解，导致花色素苷褪色，Na2S2O7可提高花色素苷的稳定性，形成花色素苷SO^-3复合物，可见，荔枝采用后果皮累积的活性氧对花色素苷的降解作用可能与果皮褐变具有密切关系。     

橄榄果实成熟和贮藏期间果皮色素的变化

研究了檀香橄榄果实在成熟和贮藏期间果皮色素的变化以及贮藏温度对果皮色素变化的影响 .结果表明 :随着果实的成熟 ,叶绿素含量逐渐降低 ,而类胡萝卜素含量缓慢提高 ;果实贮藏期间 ,果皮叶绿素 (包括叶绿素 a和叶绿素 b)含量逐渐降低 ,而类胡萝卜素含量缓慢提高 ,叶绿素 b的降解速度比叶绿素 a快 ,所以叶绿素 a/叶绿素 b的比率上升 ;低温贮藏可抑制叶绿素的降解和类胡萝卜素的形成 ,长时间保持果实鲜绿色 ,提高橄榄果实的商品价值和外观品质     

Chalcone synthase expression and pigments deposition in wheat with purple and blue colored caryopsis

Red and white caryopses are typical in common wheat. Genotypes with purple and blue caryopses are also described. This coloring is caused by anthocyanins which deposit in the pericarp (purple) or aleurone layer (blue). The anthocyanins biosynthetic pathway is well described. The key enzyme is chalcone synthase (CHS). It catalyzes the first step. We observed the deposition of anthocyanins in the pericarp and aleurone layer, the expression of a chalcone synthase gene and the amount of two anthocyanins - cyanidin-3-glycoside (pericarp of purple caryopses), and delphinidin-3-glycoside (aleurone layer of blue caryopses) during caryopsis development. Purple pigment deposition was not homogeneous and/or uniform. At first, small isolated spots of purple color were formed and thereafter they expanded. In blue caryopses, however, the coloring process was more homogeneous. The expression of chalcone synthase mRNA occurred five days before pigment deposition and finished earlier than expected. Amounts of cyanidin-3-glycoside and delphinidin-3-glycoside increased in a similar manner. Amounts of these fell at the end of caryopses development probably due to formation of more complex substances.     

荔枝果实采后商品化处理和贮藏技术

荔枝是我国南方著名的主要亚热带果树，但其果实成熟于高温季节，采后由于果皮褐变(即失去红色)和果实腐烂而使果实迅速劣变，常温下的采后寿命少于3 d，这种短的采后寿命严格限制荔枝的长距离贮运、销售和消费。因此，荔枝采后技术研究成为荔枝生产的关键问题。该文全面地介绍了荔枝果实采后腐烂和损失的原因（即荔枝果实的结构特性、生理和病理原因），荔枝果实采后商品化处理和贮藏技术，包括不同品种的耐贮运性、采收成熟度和采收方法、选别和分级、杀菌剂浸泡、减少失水处理、减少果皮褐变和保持果实红色处理（如熏硫处理、酸浸或塑料包装）、检疫杀虫处理、预冷、包装、贮藏（常温贮藏、低温贮藏、气调贮藏、自发气调贮藏）、运输和销售。     

黑米皮抗氧化活性物质的提取与分离工艺研究

该研究以总抗氧化能力为活性跟踪指标，应用正交试验研究了黑米皮抗氧化活性物质的提取条件。结果表明，黑米皮抗氧化物提取的最佳浸提条件为：以黑米皮为材料，以60%乙醇为溶剂，料液比1∶4、浸提温度60℃、浸提时间4 h。在此条件下，一次浸提率达71.4%，二次浸提率达85%以上。在去除黑米皮抗氧化提取物中的杂质时，选用石油醚或正己烷进行脱脂处理，对其总抗氧化能力的影响最小。通过静态与动态吸附性能比较，从8种大孔吸附树脂中筛选出对黑米皮抗氧化活性物质吸附性能最好的树脂为NKA-II，其最佳解吸剂为70%乙醇溶液。经NKA-II吸附分离后，黑米皮抗氧化提取物的总抗氧化能力提高4.00倍，总花色苷含量提高4.01倍。