凉粉草基因组DNA提取与分析

[目的]为分子生物学研究提供高质量、高产量的凉粉草总DNA。[方法]采用改良CTAB法提取总DNA,通过测定OD260/OD280值、琼脂糖凝胶电泳和RAPD扩增对所得DNA的浓度和质量进行检测,考察该方法对DNA的提取效果。[结果]改良CTAB法提取的总DNAOD260/OD280值为1.6～2.0;电泳条带清晰,完整性好,纯度高,总DNA分子量与λDNA相近;以所提DNA为模板进行RAPD扩增时,可得到稳定的扩增条带。[结论]改良CTAB法适合凉粉草基因组DNA的提取。     

工业化生产树脂增强杨木的性能与评价

测试分析了工业化生产的脲醛树脂增强大规格杨木锯材的物理力学性能,及其应用于实木家具的相关性能,并与2种实木家具材的性能进行了对比。结果表明:相比于素材杨木,树脂增强改性的杨木密度大幅提高,干缩性能有所改善,湿胀率和平衡含水率明显降低;各项力学性能显著提高;甲醛释放量达到E0级;与白乳胶胶合效果良好;硝基漆漆膜附着力达优等品要求,且涂饰前后材色和纹理方面的视觉性能良好;机械加工性能适用于各种加工方式。树脂增强杨木可作为轻型承重件或在对强度、硬度有一定要求的特殊场合使用,能满足实木家具用材的要求。     

盒式气调包装机气体置换结构内部3-D流场的模

气体置换装置是气调包装机的核心部件.以盒式气调包装机中2种典型气体置换装置结构为研究对象,建立了2种气体置换结构的物理模型和包装盒内气体流场分析数学模型,应用Fluent软件对包装盒内的气体流场进行三维数值模拟.建立了保证气体置换质量的包装盒内三维流场评价指标,分析了气体置换装置充、排气孔的结构布置与排列方式对气体置换性能的影响.结果表明,与传统结构相比,新设计结构在气体置换率、流场静压分布、气体平均流速以及耗气量等方面均具有更佳的性能.     

Effect of active modified atmosphere packaging with different initial gas compositions on nutritional compounds of shiitake mushrooms (Lentinus edodes)

The effect of active modified atmosphere packaging with different initial gas compositions on fresh shiitake mushrooms was investigated. Shiitake mushrooms were packaged under each of the following conditions: (1) high oxygen packaging (HOP), 100% oxygen initially; (2) medium oxygen packaging (MOP), 50% O₂ and balanced with N₂ initially; (3) low oxygen packaging (LOP), 3% O₂/5% CO₂, balanced with N₂ initially. Passive modified atmosphere packaging with air inside initially (AIR) was used as the control treatment. All the packaged samples were stored at 10 °C with 90% RH for 7 days. During storage, gas compositions, electrolyte leakage, crude water-soluble polysaccharides, total phenolic content and free amino acid content were determined. The results showed that ethanol release was high in LOP and AIR but retarded in MOP and HOP. No packaging could prevent the decrease in polysaccharide content decreasing. Both the active and passive modified atmosphere packaging maintained the color and integrity of the mushrooms. The active modified atmosphere packaging had a significant effect on the increase of total phenolic content and total amount of free amino acids. LOP had a harmful impact on mushrooms with high levels of electrolyte leakage. In conclusion, HOP and MOP had a better effect on maintaining the nutritional compounds of shiitake mushrooms.     

热激修饰瑞士乳杆菌对Cheddar干酪成熟的影响

研究了瑞士乳杆菌Lactobacillus helveticus 6024经热激修饰后,与干酪成熟相关的生化性质变化及其对Cheddar干酪成熟的影响。结果表明:瑞士乳杆菌经70℃、10 s的热激处理后,在10%脱脂乳中经32℃、6 h培养后,其产酸能力仅为6.4%,而与干酪成熟密切相关的平均氨肽酶活力,仍有约25%的保留。热激处理后的菌株加入到干酪中对其组分没有显著影响,但对干酪可溶氮水平有不同程度的影响。与未添加热激菌株的干酪对照组相比,总可溶氮含量增加不显著,而在成熟3个月时5%磷钨酸可溶氮占总氮比例增加2倍,组间差异显著。干酪质构、微观结构分析的结果也证明,热激修饰菌株对促进干酪成熟具有促进作用。     

太子参水煎液对脾虚型大鼠肠道菌群的影响

目的探讨太子参水煎液(Pseudostellaria heterophylla Decoction,PHD)对于脾虚型大鼠肠道菌群的调节作用。方法采用苦寒泻下法制备脾虚大鼠模型,分为空白组、模型组、太子参水煎液组和阳性对照组,水煎液组和阳性对照组分别灌胃给予PHD和金双歧溶液,模型组和空白组给予等量生理盐水;14 d后采集盲肠内容物进行16S rDNA?则序。结果与模型组比较,在科水平:水煎液组Prevotellaceae的相对丰度显著增加(P<0.01),Lachnospiraceae的相对丰度亦显著增加(P<0.05),Peptostreptococcaceae的相对丰度显著降低(P<0.01);在属水平:Prevotella、Agathobacter、Fusicatenibacter的丰度显著提尚(P<0.05),Rombutsia的丰度显著降低(P<0.05)。结论太子参水煎液可在一定程度上改变大鼠肠道菌群组成,进而对脾虚病症产生影响。     

Changes in antioxidant activity and postharvest quality of sweet pomegranates cv. Hicrannar under modified atmosphere packaging

The effects of different modified atmosphere packaging (MAP) on antioxidant compounds and storage quality of ‘Hicrannar’ sweet pomegranates were investigated during long term storage. Pomegranates were harvested at the commercial harvest stage and packed in two different types of MAP (MAP1 and MAP2). After packaging, all fruit were stored at 6 °C and 90–95% RH for 120 days, then removed from storage for different quality analyses. Some fruit were kept at 20 °C for 3 days to simulate a period of shelf-life. Fruit weight loss, decay index, skin color, total titratable acidity, total soluble solids content, total phenolics, total anthocyanins and antioxidant activity were determined. Internal atmospheres created by the MAP were periodically assessed during cold storage, and CO₂ concentrations increased and O₂ concentrations decreased inside the MAP. MAP significantly reduced weight loss after both 120 days of cold storage and shelf-life. MAP2 was the most effective packaging in reducing weight loss. Storage of pomegranates in MAP also reduced decay and the decay index, and maintained visual appearance compared to control fruit. During storage, a decrease in L* and C* values and an increase in h° values were observed in all treatments. However, fruit stored in MAP2 had higher L*, C* and lower h° values than in other treatments. Titratable acidity and total soluble solids decreased after cold storage and shelf-life, and no significant differences among treatments were found. Total phenolics, total anthocyanin contents and antioxidant activity increased during the storage period in control fruit.     

Pre-harvest calcium application increases biomass and delays senescence of broccoli microgreens

Microgreen consumption has been steadily increasing in recent years due to consumer awareness of their unique color, rich flavor, and concentrated bioactive compounds. However, industrial production and marketing is limited by their short shelf-life associated with rapid deterioration in product quality. This study investigated the effect of pre-harvest calcium application on the post-harvest quality and shelf-life of broccoli microgreens. Broccoli microgreen seedlings were sprayed daily with calcium chloride at concentrations of 1, 10 and 20 mM, or water (control) for 10 days. The fresh-cut microgreens were packaged in sealed polyethylene film bags. Package headspace atmospheric conditions, overall visual quality and tissue membrane integrity were evaluated on days 0, 7, 14, and 21, during 5 °C storage. Results indicated that the 10 mM calcium chloride treatment increased the biomass by more than 50%, and tripled the calcium content as compared to the water-treated controls. Microgreens treated with 10 mM calcium chloride spray exhibited higher superoxide dismutase and peroxidase activities, lower tissue electrolyte leakage, improved overall visual quality, and reduced microbial growth during storage. Furthermore, calcium treatment significantly affected expression of the senescence-associated genes BoSAG12, BoGPX6, BoCAT3 and BoSAG12. These results provide important information for commercial growers to enhance productivity and improve postharvest quality and shelf-life, potentially enabling a broadening of the retail marketing of broccoli microgreens.