The Deglet-Noor Date Polyphenoloxidase Activity Is Very Thermolabile and Exhibits Peculiarities in Its Thermal Inactivation Kinetics

In our current research on the preservation of the Deglet-Noor date quality during thermal processing, the heat inactivation of the polyphenoloxidase in enzyme extracts of this fruit was investigated. In contrast to previous studies on this enzyme in this exotic fruit, we performed full kinetic analyses at different temperatures (25-70°C) and enzyme activity was measured by the initial velocity methodology. The heat-inactivation of the polyphenoloxidase from the Deglet-Noor date does not obey a simple “one step-two stages” mechanism. All the recorded kinetics were described using a simple three parameters-biexponential model that we previously showed to be a common arranged form of kinetic expression for the known wide diversity of mechanisms of enzyme deactivation. The values of the two rate constants of the model were collected for four temperatures, ranging from 25 to 70°C and their variation was analyzed through the ARRHENIUS's law to determine the Ea values (11.83 and 54.71 kJ mol^-1, respectively). Possible explanations and implications of such low values are discussed. These results are compared to other results from laboratory as well as elsewhere in the literature.     

Common date palm in Tunisia: chemical composition of pulp and pits

Date pulp and seeds (Phoenix dactylifera L.) of a mixture of some mature common varieties called ‘Khalti’, from the South‐Eastern region of Tunisia, were evaluated for their main chemical composition. Studies were also conducted on the profiles of the extracted oil fatty acid. The following average values (on a dry‐weight basis) were obtained from the pulp and pits, respectively: total sugars 63.38% and 8.12%, reducing sugars 51.56% and 6.63%, sucrose 11.82% and 1.49%, protein 3.86% and 5.31%, oil 0.26% and 8.33%. Gas–liquid chromatography revealed that the major unsaturated fatty acid was linoleic acid (32.77%) for the pulp and oleic acid (47.66%) for the pits, while the main saturated fatty acid was palmitic acid (20.55%) for the pulp and lauric acid (17.39%) for the pits. Myristic, stearic and linolenic acids were also found in both the pulp and seeds. The uses of common dates, which are currently used only for animal feed, are assessed with suggestions for potential uses as sources of nutraceutical fructose and edible, pharmaceutical oils.     

椰枣多糖缓解功能性便秘的作用研究

摘 要：目的 在动物水平探究椰枣多糖的通便活性。方法 采用洛哌丁胺诱导的功能性便秘小鼠模型评价椰枣多糖。将小鼠随机分为空白对照组、模型对照组、阳性对照组和低、中、高剂量椰枣多糖组;连续处理7 d后,通过排便实验和小肠运动实验来评价椰枣多糖的通便效果;采用实时荧光定量聚合酶链反应（Quantitative Real-time PCR, qPCR）检测结肠组织中水通道蛋白相关基因的表达。结果 排便实验结果表明,椰枣多糖能够显著缩短便秘小鼠首粒排黑便时间,明显增加6 h内的粪便粒数、粪便湿重以及粪便含水率;小肠运动实验结果表明,椰枣多糖显著增加便秘小鼠小肠墨汁推进率,且呈现出一定的剂量依赖性;qPCR结果表明,椰枣多糖显著下调AQP3的基因表达、上调AQP9的基因表达。结论 椰枣多糖能够显著改善洛哌丁胺引起的小鼠便秘症状,且通便效果温和、无不良副作用,可能通过调节水通道蛋白基因的表达从而增加便秘小鼠粪便含水量。     

Total lipids content and fatty acid composition of seed oils from six pomegranate cultivars

The fatty acid composition of the seed oils of six pomegranate (Punica granatum L) cultivars was qualitatively and quantitatively determined by gas chromatography. The seeds contained oil in the range 51-152 mg kg^?1 dry matter. Intervarietal differences in fatty acid composition were demonstrated (fatty acid esters as % (w/w) total fatty acid esters. Sour varieties had the highest while sour-sweet varieties had the lowest oil content. Eleven fatty acids were identified. In all varieties, the predominant fatty acids were linoleic (25.2-38.6%) and oleic acid (24.8-35.5%) followed by palmitic (18.2-22.6%), stearic (6.9-10.4%) and linolenic acid (0.6-9.9%). To a lesser extent arachidic (1.1-3.4%) and palmitoleic acid (0.2-2.7%) were also found in all varieties. Lauric, myristic, behenic and lignoceric acids were rarely detected. As far as we know linolenic (18:3), arachidic (20:0), behenic (22:0) or lignoceric (24:0) acids have not been previously reported in the seed oils of edible pomegranate varieties. Lignoceric acid has not previously been found in pomegranate seed oil.     

Physicochemical Characteristics of Date Sap “Lagmi” from Deglet Nour Palm (Phoenix Dactylifera L.)

Physicochemical properties of sap from Deglet Nour date palm (Phoenix dactylifera L.) were studied. Composition analysis revealed (on a dry-weight basis) a high content of carbohydrates (94.98 g/100 g of dry matter basis) mainly sucrose, 2.72 g/100g (dry matter basis) of proteins and 2.29 g/100 g (dry matter basis) of ash. Date palm sap also contains 7.64 mg gallic acid equivalent/100 ml of total polyphenol. Thus, date palm sap showed antioxidant activity with a percentage inhibition of the DPPH radical value of 47.64%. Surface and foaming properties were also performed by drop volume and bubbling method, respectively. Equilibrium surface tension of fresh sap was 63.51 mN/m. Freeze-drying method preserved surface activity. Native sap showed better foam power (1.03) and foam stability (1150 s) than solutions prepared from lyophilised sap (5–30 g /100g of solution). Results demonstrated that this natural juice could be regarded as functional food due to its high nutritional value, antioxidant activity, surface activity, and foam power.     

The Role of Ethylene in the Regulation of Fruit Ripening in the Hillawi Date Palm ( Phoenix dactyliferaL)

The role of ethylene in the regulation of fruit ripening in the date palm ( Phoenix dactylifera L) was investigated. It was found that the rate of CO₂ output was high initially, but the rate declined steadily as the fruit advanced in maturity, reaching its lowest level as the fruit entered the stage of physiological maturity, but then the rate of respiration increased as the fruit entered the ripening phase, reached a peak value and then declined. Ethylene emission was not detected until the 91st day from pollination when ethylene production began with a rapid increase in emission, reaching a peak value within 15 days and then declining rapidly. The peak of ethylene production preceded the climacteric peak by 7 days.     

The composition and microbial quality of pre-packed dates purchased in Greater Glasgow

Composition and microbiological contamination was measured in samples of pre-packed dates purchased from a number of stores and retail outlets in Greater Glasgow. The sugar content of dried pitted dates was c . 74%, about 10% more than reported on those packs where nutritional information was given. Potentially pathogenic bacteria like Escherichia coli, Staphylococcus aureus and Bacillus cereus were identified in some of the samples together with lactic acid bacteria, yeasts and moulds, Aspergillus flavus and A. parasiticus . Fresh dates were the most heavily contaminated of all samples, probably owing to the high moisture content.     

高空环境对鸡冠花籽油含量及其脂肪酸组成的影响

本项研究探讨高空环境对鸡冠花的影响。两种品种鸡冠花种子搭载高空气球 ,飞行高度为4 0 .112km ,飞行时间近 4h ,返回地面后播种育苗进行栽培 ,采收了一代成熟种子 ,测定其千粒重、油脂含量和脂肪酸组成 ,并与地面对照组进行比较。结果表明 ,搭载实验种子千粒重增加 ,主要脂肪酸含量与对照组相比产生显著差异 ,而籽油含量无明显改变。     

紫苏子油中游离脂肪酸的动态分析

采用毛细管气相色谱的方法,以十五碳烷酸为内标,对紫苏子油中的五种游离脂肪酸:棕榈酸(C16:0)、硬脂酸(C18:0)、油酸(C18:1)、亚油酸(C18:2)、亚麻酸(C18:3)进行分析,研究紫苏子油中五种游离脂肪酸在储藏期间的变化.此分析方法无需进行甲基化,直接分析游离脂肪酸的变化.研究中对每种脂肪酸都作了方法学研究,脂肪酸的线性范围在147～922 ppm之内,12值≤0.9997.精密度≤2.43%(n=5).最后用此法测定了不同储藏期间的样品,结果显示随储藏时间的延长,游离脂肪酸的总量增加,但各脂肪酸的变化情况不同.     

石榴籽油脂肪酸成分的分析

石榴籽经石油醚提取、皂化和甲基化得到的总脂肪酸甲酯经GC分析,共检出9种成分。经GC-MS联机分析,确定脂肪酸成分为棕榈酸(2.47%)、亚油酸(4.85%)、油酸(4.07%)、硬脂酸(1.66%)、石榴酸(81.62%)、二十碳烯酸(0.53%)、花生酸(0.44%)及两个未鉴定的石榴酸三烯异构体(3.13%)。主要成分为共轭三烯不饱和脂肪酸石榴酸(9Z,11E,13Z-十八碳三烯酸),达81.62%。     

茶叶籽油与油茶籽油理化性质及脂肪酸组成比较

在对茶叶籽及油茶籽的外观、含仁率、含油率等进行测定的基础上,对茶叶籽油及油茶籽油的理化性质及脂肪酸组成进行了分析。结果表明,茶叶籽及油茶籽外观相差较大,茶叶籽油与油茶籽油在折光指数、酸值、碘值和皂化值等理化性质上较接近。脂肪酸组成上,油酸、亚油酸、棕榈酸为茶叶籽油及油茶籽油中含量最多的三种脂肪酸,油酸含量分别为52.13%和73.67%,亚油酸24.32%和11.09%,棕榈酸17.36%和10.63%。茶叶籽油和油茶籽油的单不饱和脂肪酸含量分别为54.12%和75.78%,多不饱和脂肪酸含量为24.55%和11.39%。茶叶籽含油率为19.88%,茶叶籽油潜在年产量可达15余万t。其必需脂肪酸含量是油茶籽油的2.15倍;不皂化物含量为0.77%,比油茶籽油高出22%;茶叶籽油脂肪酸比例均衡,适于人体的吸收,具有开发应用的潜力。