乌梅提取液对大肠杆菌的抑菌特性研究

为研究乌梅提取液对大肠杆菌的抑制特性,该文对不同浓度提取液、培养基pH值、热处理、环境离子浓度及暴露时间对提取液抑菌活性的影响进行了研究。结果表明:最低抑菌浓度为12.5 mg/mL,在酸性条件下提取液具有较高的抑菌活性,提取液对温度较为稳定,适用于采用巴氏杀菌的食品当中,乌梅提取液对钠离子适应性好,而钙离子可显著降低其抑菌活性,提取液在短时间内(4 d)暴露于空气中对其抑菌活性影响较小,但长时间仍然会显著降低其抑菌活性。研究结果表明乌梅提取液对大肠杆菌具有较好的抑菌效果,受环境条件影响较小,为乌梅天然食品防腐剂的开发提供了理论基础。     

青梅烟薰过程中挥发性风味物质的变化

采用同时蒸馏萃取法结合气质联用仪、以邻二氯苯为内标,分别对新鲜青梅和不同烟薰阶段的乌梅中的挥发性风味成分进行定性和半定量分析。结果表明:青梅、烟薰12、24、36和48 h的乌梅中的挥发性成分的种类分别为26、34、49、50和56种。挥发性物质的相对含量百分数变化分别为:酚类从0.75%增加到30.15%,碳氢化合物从13.29%增加到30.62%,酯类从23.35%减少到2.85%,醇类从6.74%减少到0.18%,酸类从37.27%减少到12.52%,羰基类从17.49%减少到10.86%。青梅中的主体风味物质为酯类、醇类和羰基类化合物。乌梅中主体风味物质为酚类、羰基类。     

Comparative Study of Tocopherol Contents and Fatty Acids Composition in Twenty Almond Cultivars of Afghanistan

Afghanistan is the fourth largest producer of almonds in the world producing 78 native and 6 imported cultivars. However, till date, there have been no comprehensive data on nutrient profiles of the native cultivars. Thus, in the present investigation, tocopherol contents and fatty acid composition from the kernels of 20 selected native almond cultivars of Afghanistan were analyzed. The ranges of variability for the studied nutrients were similar to those already reported for almonds grown in other countries, such as 47.8–66.1% of total lipids (fresh weight basis), 62.54–81.57% of oleic acid in the total lipids, and 139.1–355.0 μg/g α-tocopherol in kernels. With respect to cultivars, significantly (p < 0.05) high content of total lipids were recorded in ‘Belabai’ and ‘Sattarbai’ (Afghan grade), oleic acid in ‘Khairodini’ and of α-tocopherol in ‘Khairodini-161 Samangan’ and ‘Belabai’ cultivars. Kernels from these cultivars can be used for nutrient dense food formulations. Daily consumption of 50 g almonds is sufficient to meet the RDA of α-tocopherol (15 mg/day), considering the average 300 μg/g of α-tocopherol in Afghan almonds. Also, these nutrient rich cultivars can be used in almond breeding programs globally, to focus on improving kernel oil composition and nutrient contents.     

光核桃仁油和蛋白质同步提取工艺优化及油脂品质分析

以西藏光核桃为原料,采用水剂法提取结合酶法破乳技术分离其中的油脂和蛋白质,优化了光核桃仁油脂与蛋白质水剂法同步提取的工艺条件,并分析了油脂的主要理化指标及脂肪酸组成。结果表明:西藏光核桃仁油与蛋白质同步提取最优工艺为物料粒径150目、液料比8:1 (mL/g)、pH 10、浸提温度50℃、提取时间5h、搅拌速度80r/min,该工艺条件下核桃仁油提取率为(67.79±2.97)%,蛋白质提取率为(78.13±1.53)%。光核桃仁油脂具有优良的理化性质,并检测出12种脂肪酸组分,主要由顺式油酸(57.32%)、亚油酸(31.65%)、棕榈酸(6.49%)和硬脂酸(2.29%)组成,其中饱和脂肪酸7种,单不饱和脂肪酸3种,多不饱和脂肪酸2种;油脂以不饱和脂肪酸为主,相对百分含量为89.43%,其中多不饱和脂肪酸相对百分含量为31.76%,单不饱和脂肪酸相对百分含量为57.67%。     

Effect of chitosan on incidence of brown rot,quality and physiological attributes of postharvest peach fruit

The effect of chitosan (5.0 and 10.0 mg ml ⁻¹) on the incidence of brown rot (caused by Monilinia fructicola), quality attributes and senescence physiology of peaches was investigated. It was found that both concentrations of chitosan reduced the incidence of brown rot significantly and delayed the development of disease compared with the control, but were less effective than the fungicide prochloraz. Chitosan‐treated peaches were firmer and had higher titratable acidity and vitamin C content than prochloraz‐treated or control peaches. Compared to control (water‐treated) peaches, chitosan‐treated peaches showed lower respiration rate, less ethylene and malondialdehyde (MDA) production, higher superoxide dismutase (SOD) activity and better membrane integrity. Hence it can be concluded that chitosan has the potential to control brown rot, preserve valuable attributes and prolong the shelf life of postharvest peaches, presumably because of its antifungal property and inhibition of the ripening and senescence process of postharvest peaches. © 2000 Society of Chemical Industry     

Genome-Wide Identification of the Xyloglucan endotransglucosylase/Hydrolase (XTH) and Polygalacturonase (PG) Genes and Characterization of Their Role in Fruit Softening of Sweet Cherry

Fruit firmness is an important economical trait in sweet cherry (Prunus avium L.) where the change of this trait is related to cell wall degradation. Xyloglucan endotransglycosylase/hydrolase (XTH) and polygalacturonases (PGs) are critical cell-wall-modifying enzymes that occupy a crucial position in fruit ripening and softening. Herein, we identified 18 XTHs and 45 PGs designated PavXTH1-18 and PavPG1-45 based on their locations in the genome of sweet cherry. We provided a systematical overview of PavXTHs and PavPGs, including phylogenetic relationships, conserved motifs, and expression profiling of these genes. The results showed that PavXTH14, PavXTH15 and PavPG38 were most likely to participated in fruit softening owing to the substantial increment in expression during fruit development and ripening. Furthermore, the phytohormone ABA, MeJA, and ethephon significantly elevated the expression of PavPG38 and PavXTH15, and thus promoted fruit softening. Importantly, transient expression PavXTH14, PavXTH15 and PavPG38 in cherry fruits significantly reduced the fruit firmness, and the content of various cell wall components including hemicellulose and pectin significantly changed correspondingly in the transgenic fruit. Taken together, these results present an extensive analysis of XTHs and PGs in sweet cherry and provide potential targets for breeding softening-resistant sweet cherry cultivars via manipulating cell wall-associated genes.     

UPLC-UV-QDa联用系统快速分析野生樱桃李叶化学成分

采用UPLC-UV-QDa联用系统测定了4种不同野生樱桃李叶中黄酮苷元的含量,并对醇提物成分进行快速分析。结果表明,槲皮素和山奈酚为野生樱桃李叶主要黄酮苷元。UPLC测定2种苷元可在7.0min内达到基线分离,线性关系良好,平均回收率分别为98.65%(RSD=1.08%,n=3),102.02%(RSD=1.17%,n=3),表明该方法快速、准确、重复性好。不同品种和生长环境的野生樱桃李叶中黄酮苷元含量有差异,但均以山奈酚为主。阳坡紫果叶山奈酚含量最高为(7.68±0.45)mg/g,沟谷红果叶最低为(4.59±0.32)mg/g,总黄酮含量变化幅度为16.21～33.25 mg/g。通过UPLC-UV-QDa联用系统快速鉴别,阳坡紫果叶醇提物主成分为1种单咖啡酰奎宁酸、4种槲皮素苷、7种山奈酚苷。