不同成熟期番石榴果实品质特征与评价

目的 比较不同品种、不同成熟期的番石榴（Psidium guajava Linn.）果实品质特征。方法 采用国家标准方法,对不同品种不同成熟期番石榴果实的食用品质、外观品质和营养品质进行测定和分析。结果 番石榴各品种食用品质随果实发育成熟而明显提高,始熟期均表现出质地硬、汁液少、涩味重等共性,至完全成熟期食用状态最佳,‘水蜜’番石榴食用品质最好,‘珍珠’次之。不同成熟期红宝石的纵径、横径、单果重均显著高于相同成熟期的其它品种(P<0.05)。同一品种不同成熟期果实的纵径、横径和单果重,从始熟期至成熟期再至完全成熟期,均表现出显著上升的趋势(P<0.05),‘水蜜’的果形指数维持在<1.0,其余3个品种果形指数均维持在≥1.0。从始熟期至完全成熟期,4个品种番石榴果实含水量显著提高(P<0.05),淀粉、粗纤维含量均显著下降(P<0.05)。4个番石榴品种的总糖均主要由还原糖和蔗糖组成,且对于每个品种每个成熟期还原糖含量均高于蔗糖,还原糖、蔗糖、总糖含量随着果实成熟度的提高显著上升。在果实完全成熟期,还原糖、蔗糖、总糖均以 ‘红宝石’的含量最高,分别为32.74%、28.97%、63.16%,4个品种果糖含量范围为9.77~12.05%,葡萄糖为3.70~10.17%,每个品种的果糖含量均高于葡萄糖,品种之间葡萄糖含量差异较大。不同成熟期总酸含量均以‘珍珠’最高,其含量范围为5.32~7.58 g/kg。 结论 各成熟期‘水蜜’食用品质均最好,但外观差,‘西瓜’食用品质最差、含糖量最低。完全成熟期,‘珍珠’食用品质仅次于‘水蜜’,含糖量仅次于‘红宝石’,蛋白质含量最高,果实综合品质最佳,适于鲜食、制果汁,‘红宝石’含糖量高、个大,适于果茶、果酒加工。     

Quality assessment of heat-treated wood by NIR spectroscopy

NIR spectroscopy was tested for predicting the properties of heat treated wood using pine (Pinus pinaster) and eucalypt (Eucalyptus globulus) woods with two types of treatment: in oven and in a steam autoclave. Mass loss, equilibrium moisture content, dimensional stability, MOE, bending strength, colour CIELAB parameters and extractives content were determined. NIR spectra were obtained using a fibre probe on the radial surface of the samples. NIR models for mass loss showed very high coefficients of determination (R²) for cross validation ranging from 96–98%. The models obtained for wood properties were in general good with coefficients of determination ranging from 78–95% for equilibrium moisture content, 53–78% for dimensional stability, 47–89% for MOE, 75–77% for bending strength and 84–99%, 52–96% and 66–98% for colour parameters L, a^* and b^*, respectively. R² of the models for extractive content varied between 41.9–79.8% for pine and between 35.3–82.2% for eucalypt wood. NIR spectroscopy showed a good potential for quality control and characterization of heat treated woods.     

黄色和紫色百香果籽油抗氧化作用的对比研究

本论文对比分析了两种百香果籽油中的抗氧化物质含量。两种百香果籽油中均含有黄酮、β-胡萝卜素和维生素E,其中黄酮含量最高,达到45μg/m L左右,黄色百香果籽油和紫色百香果籽油的总酚含量分别达到16.69、15.82 mg GAE/kg。比较分析了两种百香果籽油对铁离子的还原能力和对DPPH自由基、超氧阴离子自由基（O-2·）和羟自由基（·OH）的清除效果等的抗氧化作用,结果紫色百香果籽油的铁离子还原能力和清除DPPH自由基的能力强于黄色百香果籽油,而清除羟自由基和超氧阴离子能力则相反,两种百香果籽油对DPPH自由基的最高清除率都高于84%,对超氧阴离子自由基的最高清除率都超过80%。实验结果表明两种百香果籽油均具有较强的抗氧化活性。      

Storage stability of a tropical fruit (cashew apple,acerola, papaya,guava and passion fruit) mixed nectar added caffeine

Nectars are formulated beverages with a fruit juice or pulp as its main component. A blend of fruits can also be used, with the advantage of combining sensory and nutritional properties of different fruits. The beverages may be added with some energetic component, as caffeine, known by its stimulating effect on central nervous system. The objective of this study was to develop mixed nectar of cashew apple, papaya, guava, acerola fruit and passion fruit added caffeine. The beverage was prepared with 35% juice blend and 10% sugar, added with 100 mg of caffeine L^?1 and 60 mg of sodium metabisulfite (SO₂) L^?1 and 500 mg of sodium benzoate L^?1 as preservatives, packed in cleaned pasteurised bottles and heat processed at 90 °C for 30 s. Physicochemical, microbiological and sensory analyses of the beverage were performed initially (time zero) and during 6 months of storage at room temperature (about 25 °C). The products were microbiologically stable during storage. The vitamin C content decreased significantly throughout storage time, although it has remained relatively high. The product presented good sensory acceptance, which suggests its potential for market.     

近红外光谱法快速检测饮料中的日落黄

合成色素是食品中最常见的一种添加剂,如果不规范使用将对人体健康产生潜在危害。该研究中光谱扫描范围为1100~1650nm,分辨率0.2nm,通过对不同浓度的日落黄溶液扫描,将得到的原始光谱图经过一阶导数、二阶导数等方法进行预处理。然后通过修正的最小二乘法(MPLS)结合变量标准化且去散射处理(SNV Detrend)的光谱预处理手段建立了相关的MPLS模型。最后利用所建模型,对饮料中的色素含量进行预测。预测相关系数为0.985,预测标准差为0.09%,相对分析误差为3.51。结果表明:近红外光谱可作为一种简单、快速、无损、可靠的方法用于检测饮料中的日落黄。     

Mid-infrared spectroscopy and chemometrics for determining the type of fruit used in jam

Fourier transform infrared spectra of jams were analysed by chemometric methods with the aim of differentiating between ‘strawberry’ and ‘non-strawberry’ containing jams. Spectra were subjected to a data reduction step, which was either principal component analysis (PCA)-based or partial least squares (PLS)-based, before being classified in one of the two jam types on the basis of the smaller distance to the group ‘means’. Diffuse reflectance infrared spectra of the insoluble materials of the jams led to a success in classification of almost 100%. However, the preparation method was lengthy and still needs some improvement. Attenuated total reflectance spectra of jams were classified according to fruit type with 91% success. This method was found to be strongly influenced by the spectral differences between ‘normal’ and ‘reduced’ total sugar content jams, which appeared in the first principal component in both the PCA-based and the PLS-based method.     

Chemical, technological and in vitro antioxidant properties of mango, guava, pineapple and passion fruit dietary fibre concentrate

The aim of this work was to determine the chemical, technological and in vitro antioxidant properties of co-products from the industrialisation of some tropical exotic fruits, such as mango, pineapple, guava and passion fruit, and to evaluate their potential use as dietary fibre sources for food enrichment. Proximate compositions were determined, as well as the total, insoluble and soluble fibre contents. The water holding, oil holding and swelling capacities were also determined. For the antioxidant activity, three different test systems were used (ABTS, DPPH and FRAP). The dietary fibre content of the co-products varied in a range between 69.1 and 81.5g/100g on a dry matter basis with a good balanced ratio between insoluble dietary fibre and soluble dietary fibre. Phenol recovery was dependent on the fruit type and the solvent system used. Methanol:acetone was a more efficient solvent for extracting phenols than ethanol. There was a good correlation between total phenol content and antioxidant capacity of the fruit extracts. All samples analysed had good antioxidant capacity. The results of this study indicate that exotic fruit fibres obtained as co-products in the process to obtain juice may be considered a good source of natural compounds with significant antioxidant activity.     

Deacidification of passion fruit juice by ultrafiltration and ion-exchange processes

Deacidification of passion fruit juice by a combination of ultrafiltration (UF) and ion-exchange was studied. Prefiltering the juice by UF facilitated the ion-exchange process. At a feed rate of 700 ml h⁻¹, weakly basic resins removed nearly 95, 80 and 50% titrat-able acids from five, seven and twelve bed volumes of UF permeate, respectively, and did not cause significant sugar losses. UF retentate can be added back to the deacidified UF permeate to restore the suspended solids and some flavour components.     

化学计量学结合NIR对浓香型白酒年份、等级的研究

研究白酒基酒中年份、等级的快速检测方法,经过近红外光谱分析,进行各种预处理和建模方法.结果表明:白酒基酒中典型醇和脂的特异吸收范围在4833～6846?cm-1,分别建立年份、等级的近红外模型,确定LSSVM模型是试验最佳的建模方法,最佳的预处理方法分别为SNV和1d+SNV,年份的近红外模型的校正集和验证集的决定系数...     

Comparison of NIR and MIR spectroscopic methods for determination of individual sugars,organic acids and carotenoids in passion fruit

In this work, NIR and MIR spectroscopy was investigated and compared for predicting passion fruit ripening parameters as sugars, organic acids and carotenoids. Spectra of 56 samples of the lyophilized passion fruit were collected using an integrating sphere in NIR range and attenuated total reflectance accessory in MIR range. Individual sugars (sucrose, glucose and fructose), organic acids (malic and citric acids) and carotenoids (β-carotene) contents were determined by reference methods. Spectral and reference data were analyzed by principal component analysis. Partial least square regression (PLSR) was used to establish calibration models. MIR technique was better than the NIR technique for glucose (R²_v = 0.942), fructose (R²_v = 0.855), sucrose (R²_v = 0.818), total sugar (R²_v = 0.914) and citric acid (R²_v = 0.913) content determination. On the other hand, NIR was superior for total acids (R²_v = 0.903) content determination. For malic acid and β-carotene contents both methods were unsatisfactory due to low concentrations of these constituents in the passion fruits.     

Application of near infrared (NIR) spectroscopy coupled to chemometrics for dried egg-pasta characterization and egg content quantification

Dried egg pasta is an important and traditional food in the Italian cuisine, and the eggs in pasta improve its nutritional value and organoleptic properties. For this reason the percentage of eggs present in the products sold as “egg pasta” has to always be clearly reported in the label. In this respect, the present research addresses the possibility of developing a method which would allow fast, simple and economic determination of egg content in dried egg-pasta, using near-infrared spectroscopy and chemometric analysis. However, as it is very likely that the spectroscopic fingerprint can also be affected by the manufacturing process of this product, in particular by drying temperature and time, the effect of the manufacturing process on the spectral profile of egg-pasta samples was thoroughly investigated, using experimental design coupled to a multivariate exploratory data analytical technique called ANOVA–Simultaneous Component Analysis (ASCA). Moreover, once confirmed the significance of the drying effect on spectral shape, with the aim of building a calibration model to quantify the egg content in pasta samples irrespective of the manufacturing protocol adopted, a non-linear approach based on local regression, namely LWR-PLS, was investigated. This method allowed the determination of the egg content in external validation samples with low error (RMSEP = 1.25), resulting in predictions more accurate and precise than those obtained by a global PLS model.     

百香果山药复合果酒酿造工艺研究

以百香果和山药为原料进行复合果酒酿造工艺研究.研究结果表明,百香果汁与山药汁的最佳配比为1：2;最佳发酵工艺为初始糖度28％,酵母接种量0.03％,发酵温度25℃,发酵时间8d.成品果酒色泽呈浅黄色,有典型的百香果和山药风味,酒香清醇,口感清爽,酸甜适中,澄清透亮.果酒酒精度14.03％vol,DPPH自由基清除率98.83％.     

Post-harvest changes in some volatile flavour constituents of yellow passion fruit (Passiflora edulis f. flavicarpa)

The yellow passion fruit (Passiflora edulis f. flavicarpa) was stored after harvest at ambient temperature (29 ± 2°C). Volatile flavour components were analysed up to a period of 15 days using a headspace technique combined with high-resolution gas chromatography and mass spectrometry. Several compounds–ethyl butanoate, hexyl butanoate, ethyl hexanoate, ethyl acetate, 2-heptanone, benzaldehyde and 1-hexanol–were quantitatively monitored during post-harvest storage of fruit.     

Classification and analysis of citrus oils by NIR spectroscopy

A new NIRS method is introduced for the determination of valuable components in various citrus oils. Spectra of grapefruit, orange, mandarin, lemon and lime oils in the range from 1100 to 2500 nm have been registered. Applying principal component analysis to the spectral data a good separation of the different fruit oil types can be achieved. The application of multivariate statistics in conjunction with analytical reference data leads to good NIR calibration results. For the main components (e.g. limonene, γ-terpinene, sabinene) and general chemical–physical parameters (e.g. optical rotation value, aldehyde content) standard errors are in the range of the applied reference method. The multiple coefficients of determination (R²) for components with an amount of more than 1.5% are generally >0.95. Furthermore reliable in-process methods for the determination of the individual nootkatone and aldehyde contents during the isolation and purification process from grapefruit and orange oil are presented.