蒙顶黄芽加工过程感官品质及化学成分变化的研究

以蒙顶黄芽加工过程中的茶样作为研究对象,系统地分析研究蒙顶黄芽在加工过程中感官品质和化学成分的变化。结果表明:在整个加工过程中氨基酸、可溶性蛋白质和可溶性糖含量呈先升高后降低的趋势;儿茶素、咖啡碱、茶多酚、叶绿素a和叶绿素b含量随加工进程逐渐减少,其中叶绿素a和叶绿素b含量降幅较大,分别为52.00%和44.44%;水浸出物和茶色素含量随加工进程逐渐增加,其中茶红素和茶黄素含量增幅较大,分别为56.52%、54.55%;由感官审评结果可知,经三炒工序后的茶样感官品质已接近蒙顶黄芽成品的品质特征,表明蒙顶黄芽独特的品质特征经过闷黄过程已初步形成。      

Biological activity and chemical composition of different berry juices

Total phenolics, total anthocyanins, mineral content, radical scavenging activity and antiproliferative activity against human cancer cell lines were evaluated in fresh pressed juices of five different berries. Total phenolic content ranged from 133.0 to 260.3 mg of gallic acid equivalents/100 g of fresh weight, for red currant and black currant, respectively. Bilberry juice contained the highest amount of total anthocyanins (0.18%). Significant correlation between total phenolics content and radical scavenging activity was observed (r = −0.980; p < 0.01). All examined juices showed antiproliferative activity in dose-dependent manner with IC₅₀ ranging from 10.2 to 70.5 μl/ml. Black currant juice was the most effective inhibitor of proliferation in all cell lines tested (HeLa, Fem X, LS 174, MCF-7 and PC-3). Significant correlations of acidity and total anthocyanin content with antiproliferative activity of berry juices on HeLa cells, Fem X cells and MCF-7 cells were noticed. Berry juices are good sources of some minerals and contribute significantly to daily intake of these micronutrients.     

Effect of canning and storage on carotenoids (vitamin A activity) and vitamin C in Spanish and Turkish oranges

Canning caused a small reduction in the vitamin C content of orange purée of both Spanish and Turkish varieties; subsequent storage for 24 months at 10°C caused complete loss of vitamin C. Carotenoids, however, were retained to a limited extent after storage and similar amounts were present at both room temperature and at 10°C. Most of the vitamin C in the flavedo was retained after 24 months' storage at - 20°C but there was a considerable fall when the frozen material was thawed and stored at room temperature for 4 days. Thirteen carotenoids were present in both varieties of purée, with three additional ones in the Spanish variety and one additional one in the Turkish variety. Despite the heating in acid conditions involved in the canning process, only two of the pigments, violaxanthin and flavoxanthin, isomerised from the all-trans to cis-trans isomers.     

不同甜橙品种抗氧化能力的比较

用3种抗氧化体系综合评价了7个甜橙品种的抗氧化能力。对·OH的清除率介于47.60%～88.62%之间,品种间存在显著的差异性,无核雪柑和血橙的清除能力最强,清家最弱;对DPPH·的清除率均在50%以上,品种间未呈现显著的差异性,以无核雪柑清除率相对较高;用ABTS/K2S2O8体系测定的反映总抗氧化能力的TEAC值介于4.79～6.09之间,血橙最高,锦橙最低。综合比较表明,血橙品种总抗氧化能力最强。     

Modulating polyphenolic composition and organoleptic properties of apple juices by manipulating the pressing conditions

Initial crushing and pressing operations have a major influence on the polyphenolic composition of apple juice, therefore, we have tested the impact of variations of this step using three cider apple cultivars of contrasting polyphenolic composition: Guillevic, Kermerrien and Dous Moen. Under inert atmosphere, increased temperature (between 5 °C and 24 °C), increased the extraction of procyanidins from fruit to juice. The crushed apples were also subjected to four conditions of oxidation: preserved from oxidation as above, short contact with air, short contact with air and mixing, long contact with air and mixing. Oxidation decreased the concentrations of native polyphenols in the juices, especially for flavan-3-ols. The golden colour of the juices was initially enhanced with increases in saturation C∗ and a shift of the hue angle from yellow to orange. However, for the highest oxidation state the colour became paler and more yellow. Bitterness and astringency decreased upon oxidation, probably due to increased retention of oxidised moieties.     

浸提工艺对冬凌草浸提液香气组成及感官品质的影响

采用热水浸提法、超声波浸提法和微波浸提法分别对冬凌草浸提,利用气-质联用仪对三种浸提方法所得浸提液的香气组成进行分析,同时对三种浸提液的感官品质进行了综合比较。结果表明,热水浸提液、超声波浸提液和微波浸提液香气成分的数量分别为40种、25种和26种,且各成分的相对百分含量有很大差异,从而导致浸提液香味由浓到淡分别为热水浸提法>微波浸提法>超声波浸提法。三种浸提方法所得浸提液的感官品质也有明显的差异,就颜色来说,由深到浅分别为热水浸提法>超声波浸提法>微波浸提法;就浸提液的稳定性来看,微波浸提法>超声波浸提法>热水浸提法,同时热水浸提法所得浸提液的苦涩味均高于另外两种方法。      

Effect of cultivar and fruit storage on basic composition of clear and cloudy pear juices

BackgroundPears due to low acidity are a suitable raw material for the production of multifruit nectars thus it is justified to determine the chemical composition and investigate the effect of cultivar and fruit maturity on juices quality.MethodsJuices from ‘Alexander Lucas’ and ‘Conference’ cultivars were produced after harvest and after 3 months of pears storage.ResultsAverage yield of clear juices was 76.4% for ‘Conference’ cultivar and 74.3% for ‘Alexander Lucas’. In the case of cloudy juices, the yield was lower by about 3%. Processing of ‘Conference’ cv. from stored fruit resulted in yield decrease compared to fruits after harvest; this was not in case of ‘Alexander Lucas’ in 2008, where juices produced from stored fruits were characterized by a higher yield compared to fresh fruit.Total solids content in clear juices was 125–135 g/L and 135–141 g/L for cloudy juices. ABTS^●+ and total phenolics analysis showed that cloudy juices were characterized by a higher antioxidant activity and phenolics content than the clear ones.ConclusionPear storage, on the contrary to apples, does not decrease their suitability for cloudy juice production. Cloudy juices as a rule have higher antioxidant activity than the clear ones.     

Improvement in end-use quality of spring wheat varieties grown in different eras

Evaluation of wheat cultivars from different eras allows scientists to determine changes in agronomic and end-use quality characteristics associated with grain yield and end-use quality improvement over time. Forty-four spring wheat cultivars introduced or released since 1933 were evaluated for quality improvement using canonical variant analysis. It was observed that there was a considerable improvement in protein content from 1933 to 1964 whereas the genetic potential for straight grade flour protein from 11.34% in 1933–1964 to 12.13% in 1991–1996. Crude protein increased by 6.95% from 1933 to 1996. Ash content and flour yield declined by 9.55% and 5.51%, respectively. Total chapati scores of modern cultivars were 8.97% higher than those of cultivars grown earlier. The average spread ratio and overall cookie scores increased almost 5.53% and 4.44%, respectively from 1933 to 1996. It was also observed that overall cookie scores were highest during the period 1981–1990. The average dry gluten and total chapati scores of varieties grown since 1991 were approximately 10.20% and 74.72% respectively, which were 4.72% and 8.97% higher than those of cultivars grown since 1933. Average spread ratio and overall cookie scores increased almost 5.53% and 4.44% from 1933 to 1996, respectively. The era (1991–1996) containing the modern varieties showed a substantial improvement in lysine content than the era containing the oldest wheat varieties. Similarly amino acid score was also found to be 4.26% higher than the varieties released during the period 1933–1964.     

不同产地和不同贮藏年限陈皮的化学成分研究进展

陈皮具有很高的药用价值,且越陈越有价值,在临床和日常食用中应用十分广泛。目前市场上除了药典规定的橘属植物及其栽培变种的果皮用作陈皮外,柑属和橙属植物的果皮也被制成陈皮,导致市场上陈皮的来源千差万别。由于不同产地品种和不同贮藏年限陈皮所含的化学成分种类和含量存在差异,其功效也存在差异,因此不同来源陈皮的化学成分和质量控制研究正受到越来越多的关注。本文主要综述了不同产地和不同贮藏年限陈皮中黄酮、挥发油、生物碱、多糖等化学成分的差异及所对应的陈皮功效的改变,为陈皮的质量控制和评价提供科学数据,为陈皮在临床及食品行业中的合理选择提供指导。     

砂梨品种果实冷藏期间质地及品质差异性评价

目的:确定砂梨品质形成及劣变关键点。方法:以早生新水、沪晶梨18、沪晶梨67为试材,将成熟度一致的3个品种的梨果实于(1.0±0.5)℃、相对湿度85%～90%的冷库中贮藏60 d,每10 d测定果实品质和10个电子鼻传感器的感应值。结果:沪晶梨18和早生新水为典型的果糖积累型,沪晶梨67为山梨醇积累型,3个品种梨均为苹果酸积累型。冷藏期间,沪晶梨67可保持较高的果实带皮硬度、果肉组织硬度、脆性和咀嚼性;含有较高的葡萄糖、山梨醇和总糖含量,可滴定酸、苹果酸含量较稳定;贮藏风味浓郁,受冷藏时间调控小,耐贮性佳。沪晶梨18的果皮特性、紧实度和脆性优于早生新水,拥有较高的果糖、苹果酸含量和果糖/总糖,可保持较高的甜酸度,贮藏风味浓郁。早生新水易软化,可滴定酸含量呈急剧下降趋势,综合风味受贮藏时间调控大,不耐贮。早生新水和沪晶梨67梨果实挥发性化合物发生了明显变化,特别是氮氧化合物、甲烷、硫化物、乙醇等挥发性化合物。结论:早生新水、沪晶梨18、沪晶梨67的安全冷藏期分别为30,40,60 d。     

Effect of UV irradiation on enzymatic activities and physicochemical properties of apple juices from different varieties

The influence of ultraviolet irradiation (UV) on some quality attributes (colour, pH, soluble solids content, formol index, total phenolics, sugars and vitamin C) and enzymatic activities (polyphenol oxidase, peroxidase and pectinolytic enzymes) of fresh apple juice was investigated. Apple juices made from four different varieties (Golden, Starking, Fuji and King David) were irradiated during 120 min with a high-pressure mercury lamp of 400 W that emits in a range between 250 and 740 nm with a resulting incident energy of 3.88·10⁻⁷ E·min⁻¹. The treatment was effective in the inactivation of the assayed enzymes. Polyphenol oxidase was inactivated in 100 min, while peroxidase was completely destroyed in only 15 min in all the four varieties. No variations were observed in pH, soluble solids content, formol index, total phenolics and sugars. The colour of the juice made from King David was unvariable during all the experiment. In the ones made from Golden, Starking and Fuji, UV radiation impaired some of the pigments present in the juice, either initially present or the ones formed later. This fact can be especially observed in the increase of the CIELab parameter L*, which increased from 23.2 to 24.6 in Fuji juice. The content of vitamin C in juices from Golden, Starking and Fuji slightly changed during the experiment, decreasing a 4.0% in Fuji juice, 5.7% in Golden one and 5.6% in Starking one. Meanwhile, in the juice from King David the loss was 70.0%. This significant difference can be attributed to the lack of pigmentation of this juice.     

微波处理强度对不同产地烟叶化学成分及感官质量的影响

采用改变微波功率、作用时间的方式,对不同地区的烟叶进行微波松散,测定松散前后总糖、总氮、植物碱、氯、钾含量,并进行对比评吸。结果表明,随着微波处理强度的加大,烟叶总糖含量呈现先升高后降低的趋势,总氮、植物碱略有降低,氯和钾含量无明显变化;较低处理强度对香气质、干净程度、细腻程度、杂气指标有一定的改善作用,但较高的处理强度对香气量、浓度有不利影响,对甜度和回味影响不明显。     

不同茶树品种桐柏玉叶茶叶的主要化学成分比较

对河南省茶树良种繁育场龙井长叶、龙井43、平阳特早、白毫早、乌牛早等5个茶树品种制成的桐柏玉叶茶的氨基酸、茶多酚、咖啡碱、叶绿素等主要化学成分进行了测定。结果表明,龙井长叶含茶多酚量最高,滋味比较浓;平阳特早含氨基酸含量最高;白毫早水浸出物含量最高,滋味比较浓厚;平阳特早所含的叶绿素量最高。     

不同品种枇杷果实采后低温贮藏品质研究

目的 明确不同品种枇杷果实采后低温贮藏期间腐烂和品质变化的差异, 为枇杷果实贮运技术的开发提供理论依据。方法 研究了“洛阳青”、“宁海白”和“大红袍”3个品种枇杷果实5 ℃贮藏35 d期间失重率、腐烂指数、果皮和果肉颜色变化、可溶性固形物、维生素C、类胡萝卜素和总酚含量的变化。结果 “洛阳青”和“大红袍”枇杷果实采后可溶性固形物、维生素C含量和L值下降, 失重率和腐烂指数上升, 果实贮藏品质发生劣变。枇杷果实贮藏前期果皮和果肉b值升高, 类胡萝卜素和总酚含量增加。但随着贮藏时间的延长, 果实中类胡萝卜素和总酚含量逐渐下降。结论 与“宁海白”枇杷果实相比, “洛阳青”和“大红袍”枇杷果实采后5 ℃贮藏期间易发生腐烂, 品质劣变严重, 耐贮性低。     

Effect of storage conditions on nutritional quality and color characteristics of quinoa varieties

To maintain grain quality and prevent loss, effective storage systems are required. The aim of this study was to evaluate the effects of storage duration (0, 60, 120, 180, 240, 300, 360 days) and temperature (4, 10, and 25 °C) on proximate and nutritional components, and color properties of Mint Vanilla and Titicaca quinoa varieties. The results showed that the increase in storage duration and temperature leads to changes in the grain moisture, protein and ash contents, nutritional component and color properties. There was an increase in ash content at 25 °C, moisture content at 10 and 25 °C, and protein content at 4 °C in the stored grains compared with the grains on the initial of storage for Mint vailla variety. Whereas, there was an decrease in ash and protein content for all the temperature at the end of 360 days storage for Titicaca variety. Overall, there was a decrease (except Fe, Zn, Co, Ni, Cd and Pb) in the nutritional component of both quinoa varieties. L1, H° and WI values decreased, and a1, b1 and C1 values increased as a function of storage duration and temperature and showed some temperature-dependent degradation for both quinoa varieties.     

不同贮藏方式对磨盘柿贮藏品质和生理的影响

为了探讨磨盘柿最佳的贮藏方式,研究了不同贮藏方式对柿果品质、生理变化和褐变底物及相关酶的影响。结果表明:冰温贮藏能较好地抑制磨盘柿的采后衰老,具体表现在延缓了果实硬度下降,维持较高的维生素C、可溶性固形物和可滴定酸含量;抑制呼吸强度的增加、推迟乙烯高峰出现的时间;抑制贮藏后期丙二醛和膜相对电导率的增加、总酚含量的下降和PPO活性的增加,保持较高的SOD活性,有效控制果实褐变的发生等方面。与普通冷藏相比,冰温贮藏可将磨盘柿贮藏期延长45d以上。     

Variations in the phenolic composition of fruit juices with different treatments

 In this work we have determined the variations in the composition of phenolic compounds of natural peach and apple juice with different thermal and enzymatic treatments. The following phenolic compounds were identified and quantified in samples of treated and untreated fruit juices: cinnamic acids (caffeic, p-coumaric and ferulic acids), cinnamic derivatives (chlorogenic and p-coumarylquinic acids and feruloylglucose), flavonols (quercetin glycosides), dihydrochalcones (phloretin glycosides), flavan-3-ols [(+)-catechin and (−)-epicatechin], and procyanidins (dimer B₂, trimer C₁ and tetramer T₄). Furfural derivatives, compounds widely used as indicators of prior thermal treatment, were also studied using these samples. The results indicate that the different processes tested gave rise to a series of changes in composition that may make it possible to identify the type of treatment employed on the basis of the composition of phenolic compounds in the fruit juices. Received: 18 March 1996     

Effect of gamma radiation and cold storage on chemical and organoleptic properties and microbiological status of liquid egg white and yolk

This investigation aims to establish a feasible radiation dose for treating liquid egg white (LEW) and yolk (LEY) at room temperature to improve their microbial safety. Samples of LEW and LEY were subjected to gamma irradiation doses of 0,1,2,3 and 4 kGy at room temperature followed by storage at 4 ± 1 °C. Then the effects of irradiation and cold storage on proximate composition, pH, soluble protein and free sulfhydryl content (SH) were determined for LEW and LEY in addition to the contents of total carotenoids in LEY. Moreover, free fatty acids (FFA) and peroxide value (PV) were determined for lipids of LEY.The microbial safety of LEW and LEY was established during storage throughout the enumeration of the total plate count, enterobacteriaceae, Staphylococcus aureus as well as the detection of Salmonella. The effects of irradiation at 3 kGy dose, which was enough for improving the microbial safety of samples, on amino acid composition of LEW and LEY and fatty acid profiles of LEY lipids were studied. In addition, sensory evaluation was carried out for liquid and scrambled egg white and egg yolk samples. The results showed that gamma irradiation and refrigerated storage had no significant effects on proximate composition and pH of liquid egg samples, while significantly decreased the contents of total carotenoids in LEY samples. Furthermore, gamma irradiation had no significant effects on protein solubility and the contents of free SH in LEW, while induced significant slight decreases in protein solubility and the contents of free SH in LEY. Cold storage, however, showed no significant effects on protein solubility and free SH in all liquid egg samples. FFA contents and PV of LEY lipids significantly increased post irradiation treatments and during storage, but the observed values were relatively low and acceptable. In addition, gamma irradiation at 3 kGy dose had no significant effects neither on the amino acid composition of LEW and LEY nor on fatty acid profiles of LEY lipids. The sensory preference did not alter neither for the liquid egg samples nor for scrambled egg samples that prepared from irradiated liquid egg products. Finally, gamma irradiation at 3 kGy dose appeared to be the optimum for treating LEW and LEY at room temperature followed by cold storage at 4 ± 1 °C.