库拉索芦荟凝胶液的提取工艺研究

以美国库拉索芦荟为原料,分别采用鲜榨汁法、冷榨汁法、超声波破碎法和酶法提取芦荟凝胶液,并分析了凝胶液的活性成分及其稳定性,结果表明:采取不同提取工艺获得的凝胶液功效成分差异明显。酶法提取获得的凝胶液出汁率高,多糖、蛋白质、有机酸及过氧化物酶含量较高,是制备高档芦荟凝胶液的最佳选择;而超声波破碎法所获得的芦荟凝胶液稳定性最好。另外,还探讨了芦荟综合利用的相关工艺,提出针对不同的应用领域应采取相应的提取工艺。     

宽皮柑桔大小年结果树矿质营养的变化

实验以15a生本地早（Citrus reticulata Blanco)为材料,研究了大、小年结果树无机营养的变化。大年结果树比小年结果树,非蛋白氮含量提高显著,蛋白氮和全氮含量降低,无机磷、有机磷和全磷含量降低,Ca显著提高而K,Mg及Fr,Mn,Cu含量处于偏低或缺乏的水平,表明大年结果树在无机营养上是贫乏的。     

温度和糖度对橙汁热导率的影响

为了深入研究橙汁热导率的影响因素,采用微热探针法测试系统,对糖度为5%~66%(质量分数)的橙汁在温度0~50℃间的热导率进行了系统测试。结果表明,对于同一糖度的橙汁,其热导率与温度呈高度线性正相关,而在同一温度条件下,橙汁的热导率与其糖度呈高度线性负相关,由此得出橙汁热导率关于温度和糖度的预测模型,通过此模型可预测0~50℃条件下不同糖度橙汁的热导率值。可见,橙汁温度和糖度均是其热导率的影响因素。     

Fruiting position during development of ‘Nules Clementine’ mandarin affects the concentration of K,Mg and Ca in the flavedo

Adequate K, Mg and Ca supply is important to develop well-structured and functional cell walls and membranes in fruit, and insufficient levels or imbalances of these minerals are known to be involved in various postharvest disorders. Microclimatic variation exists in the ‘Nules Clementine’ mandarin tree canopy and results in lower photosynthetically active radiation (PAR) levels and temperature as well as a higher humidity inside the tree canopy. The aim of this experiment was to determine the impact of this variation in microclimate on accumulation patterns of K, Ca and Mg in the flavedo of the fruit rind during stages II and III of fruit development. Fruit mass, dimensions, rind colour development and mineral composition of the flavedo were measured to describe the condition of fruit borne on the outside and inside of the tree's canopy. The data revealed that canopy position influenced mineral nutrient accumulation patterns in the flavedo. Outside fruit flavedo accumulated significantly higher concentrations of Ca and Mg in all three seasons (2005–2007). In contrast, inside fruit flavedo (shaded fruit) accumulated significantly higher levels of K compared with outside fruit flavedo. The accumulation of K and Ca differed from that of kiwifruit and apple in that Ca concentration increased and K decreased towards maturity. These results suggest that xylem, as in citrus leaves, is the main vasculature supply conduit to the citrus fruit flavedo for mineral nutrients. The reduction of transpiration potential by lower temperatures and higher humidity inside the canopy could be responsible for the reduced accumulation of Ca and Mg. The high K concentration of inside fruit flavedo is suggested to be a stress response, due to the low light levels, to maintain osmotic potential in the shaded rind tissue, and this imbalance could possibly lead to a reduction in rind condition, which manifests through rind breakdown symptom development.     

Toxoplasma gondii in Switzerland: a serosurvey based on meat juice analysis of slaughtered pigs, wild boar, sheep and cattle

Toxoplasmosis is one of the most important zoonotic diseases worldwide and is caused by the protozoan Toxoplasma gondii. Besides vertical infection during pregnancy, humans can get infected post-natally either by peroral uptake of sporulated Toxoplasma oocysts or by ingestion of tissue cysts upon consumption of raw or undercooked meat. The aim of this study was to approximate the risk of human infection via meat consumption by estimating the seroprevalence of T. gondii in slaughtered animals in Switzerland and to compare data with prevalences assessed 10 years ago. The study included pigs, cattle, sheep and wild boar of different age groups and housing conditions whenever possible and applicable. A P-30-ELISA was used to detect T. gondii-specific antibodies and to determine seroprevalences in meat juice of slaughtered animals. A total of 270 domestic pigs (120 adults, 50 finishing, 100 free-ranging animals), 150 wild boars, 250 sheep (150 adults, 100 lambs) and 406 cattle (47 calves, 129 heifers, 100 bulls, 130 adult cows) were tested. Seropositivity increased with the age of the assessed animals. Independent of the age-group, the overall seroprevalence was lowest in wild boars (6.7%), followed by pigs (23.3%), cattle (45.6%) and sheep (61.6%), respectively. Conventional fattening pigs and free-ranging pigs surprisingly had comparable seroprevalences (14.0% and 13.0%, respectively). Unlike in other European countries, where generally a decrease in the number of seropositive animals had been observed, we found that the prevalence of seropositive animals, when compared with that of 10 years ago, had increased for most species/age groups. Conclusively, the results demonstrated a high seroprevalence of T. gondii in animals slaughtered for meat production and revealed that increasing age of the animals is a more important risk factor than housing conditions in Switzerland.     

Expression of lycopene cyclase genes and their regulation on downstream carotenoids during fruit maturation of Guoqing No. 1 Satsuma mandarin and Cara Cara navel orange

Lycopene β-cyclase (LCYb) and lycopene ?-cyclase (LCYe) are believed to be crucial genes to lycopene cyclization and downstream carotenoid accumulation. To illuminate the gene expression profiles and their regulation on downstream carotenoids, expression profiles of these two genes and contents of several corresponding carotenoids were determined by real-time PCR and HPLC, respectively, in relative shorter intervals during breaker and maturation stage of Guoqing No. 1 satsuma mandarin (Citrus unshiu Marcow) and Cara Cara navel orange (Citrus sinensis Osbeck). Data showed that the expression profiles of these two cyclase genes and their relative expression levels between the peels and the pulps at the same stage all varied with cultivars. But in general, accumulation of lutein and β-carotene experienced a similar tendency in both cultivars and were up-regulated by expression of LCYb and LCYe in spite of poor correlation in the pulps. Meanwhile, lycopene abundance was negatively correlated with the expression of LCYe as expected, but hardly correlated with LCYb in the pulps of Cara Cara navel orange, indicating that LCYe might exert a more prominent influence on lycopene cyclization and downstream carotenoids formation. Results of carotenoids accumulation suggest that the biosynthetic process of carotenoids would shift from upstream β, ?- or β, β-carotenoids such as lutein and β-carotene to downstream β, β-carotenoids during fruit development.     

常德市特早熟温州蜜柑品种特性及栽培技术研究

通过多年的引种栽培,常德地区筛选出了大浦5号、大分4号、日南1号3个成熟期特早、品质上乘、综合性状优良、适应性强的新品种。介绍了新品种的特征特性及其对常德地区柑橘产业发展的意义;另外,总结了生草栽培、大棚促早栽培和极致栽培等配套技术以及常德地区推广特早熟温州蜜柑种植以来取得的成效。     

柑桔汁陶瓷膜微滤澄清和污染阻力试验

为了探讨柑桔汁微滤澄清技术及微滤膜污染阻力,建立膜清洗方法,研究以0.2 mm陶瓷膜微滤柑桔汁时膜通量变化及处理效果,结果表明：当温度30℃、压差0.16 MPa及膜面流速4 m/s时,全循环模式下稳定膜通量为22.4 L/(m2·h),浓缩模式下体积浓缩因子为12时,膜通量为10.6 L/(m2·h),澄清汁得率达91.67%;澄清汁浊度仅为0.62 NTU,澄清度高达99.93%,且各主要营养成分变化不大。通过建立膜污染阻力模型,考察操作参数对各分解阻力的影响,进而研究膜污染动力学后发现：压差对不可逆极化层阻力影响最为明显;增大膜面流速显著降低各极化层阻力,但对不可逆污染阻力作用不大;升高温度使得各阻力下降;膜污染可用拟二级速率方程描述。研究污染膜清洗过程,结果表明采用去离子水、1% NaOH和0.5% NaClO混合液、0.2% HNO3溶液依次清洗膜,膜通量可迅速恢复。     

红枣汁中维生素C热降解的动力学研究(简报)

为了了解加热温度对红枣汁中维生素C含量变化的影响,降低红枣汁在加工过程中维生素C的损失,该文以红枣澄清汁为材料,采用可逆的一级反应模型研究了不同加热温度下还原型维生素C（AA）的降解规律并推导出氧化型维生素C（DHAA）含量变化的数学模型。在此基础上利用Arrhenius 方程计算得到AA和DHAA的降解反应活化能。结果表明,在303,313,323,333,343 K温度条件下,可逆的一级反应模型适用于表达红枣汁中AA的降解规律,非线性回归决定系数r2均大于0.98。DHAA的数学模型也能较好地预测DHAA在红枣汁中的含量变化规律。在不同的加热温度下,AA与DHAA均能发生降解反应,但DHAA的降解速率较AA低,DHAA 的降解主要发生在AA 的降解反应达到平衡之后。AA热降解反应活化能较低,表明红枣汁中的AA对热处理较敏感。该研究为优化红枣汁的加工工艺、提高红枣汁的品质提供理论依据。