QUALITATIVE AND QUANTITATIVE EVALUATION OF POMELO MATURITY USING MULTIVARIATE COMBINATION OF CHEMICAL AND PHYSICAL PROPERTIES

The present study reports the use of multivariate data analysis in combining physical and chemical properties for qualitative and quantitative evaluation of pomelo maturity. Pomelos of "Thong Dee" variety were harvested at four stages of maturity: immature, early mature, late mature and over-mature. The categories of maturity were classified with discriminant analyses on all variables and only nondestructive variables. The accuracy of classification using nondestructive variables (80.0%) was comparable to that using all variables (85.0%). For the estimation of the ratio of soluble solids content to acidity designated as a maturity measure, partial least squares regression models were developed based on either all remaining variables or nondestructive variables. The predictive performances by the two models were not significantly different. The acoustic response characterized by the third resonant frequency was shown to be the most important variable in qualitative and quantitative assessment of pomelo maturity.

PRACTICAL APPLICATIONS

The results of the current study present a number of nondestructive parameters that are associated with pomelo maturity. They can be used to develop an on-line grading machine for pomelos.     

Polyphenol composition and antioxidant capacity in pulp and peel of apricot fruits of various varieties and maturity stages at harvest

Polyphenol composition and antioxidant capacities of peel and pulp tissues of six apricot varieties were determined. Variations in polyphenol and antioxidant capacity based on variety (early‐maturing varieties and late‐maturing varieties) and harvest maturity (green mature and full mature) were assessed. The results of principal component analysis revealed that (+)‐catechin made the most important contributions to the antioxidant capacities of the pulp. As the (+)‐catechin content in ‘Dajie’ apricot decreased by 36.8% from green mature to full mature, the antioxidant capacities determined by ABTS free radical scavenging assay, DPPH free radical scavenging assay and cupric ion reducing antioxidant capacity assay decreased by 50.0%, 45.2% and 45.8%, respectively. Levels of phenolic compounds in the apricot peels were approximately 2–4 times higher than those of the pulps. Quercetin‐3‐rutinoside may be substantially responsible for the antioxidant capacities of the peels. The late‐maturing varieties tended to have higher levels of phenolic compounds and higher antioxidant capacities than the early‐maturing varieties. The antioxidant capacities in green mature apricots were much higher than those of full mature apricots.     

Rapid screen of aflatoxin‐contaminated peanut oil using Fourier transform infrared spectroscopy combined with multivariate decision tree

Contamination of peanut oil is a great concern in the industry. FTIR spectroscopy combined with chemometrics could develop a rapid and nondestructive method to screen aflatoxin‐contaminated peanut oil. Aflatoxin B1 (AFB1)‐ and aflatoxin (AFT)‐positive peanut oils were screened by mid‐IR (MIR) with classification models established by a novel multivariate decision tree (MDT) method. Two discriminant functions were developed in the fingerprint region based on absorbance ratio and moving window Fisher discrimination analysis methods for the two complex nodes in each MDT model. Window adjustment reduced the total different spectral data points in modelling to 23. The true‐positive and true‐negative rate of calibration and validation could both reach up to 100%. These results would render the possibility of efficient and economical design of a portable high‐speed multitasking MIR instrument for screening AFB1‐ and AFT‐contaminated peanut oil.     

Development of algorithms for detecting citrus canker based on hyperspectral reflectance imaging

BACKGROUND: Automated discrimination of fruits with canker from other fruit with normal surface and different type of peel defects has become a helpful task to enhance the competitiveness and profitability of the citrus industry. Over the last several years, hyperspectral imaging technology has received increasing attention in the agricultural products inspection field. This paper studied the feasibility of classification of citrus canker from other peel conditions including normal surface and nine peel defects by hyperspectal imaging. RESULTS: A combination algorithm based on principal component analysis and the two‐band ratio (Q_687/630) method was proposed. Since fewer wavelengths were desired in order to develop a rapid multispectral imaging system, the canker classification performance of the two‐band ratio (Q_687/630) method alone was also evaluated. The proposed combination approach and two‐band ratio method alone resulted in overall classification accuracy for training set samples and test set samples of 99.5%, 84.5% and 98.2%, 82.9%, respectively. CONCLUSION: The proposed combination approach was more efficient for classifying canker against various conditions under reflectance hyperspectral imagery. However, the two‐band ratio (Q_687/630) method alone also demonstrated effectiveness in discriminating citrus canker from normal fruit and other peel diseases except for copper burn and anthracnose. Copyright © 2011 Society of Chemical Industry     

Enrichment of Functional Properties of Ice Cream with Pomegranate By‐products

Pomegranate peel rich in phenolics, and pomegranate seed which contain a conjugated fatty acid namely punicic acid in lipid fraction remain as by‐products after processing the fruit into juice. Ice cream is poor in polyunsaturated fatty acids and phenolics, therefore, this study was conducted to improve the functional properties of ice cream by incorporating pomegranate peel phenolics and pomegranate seed oil. Incorporation of the peel phenolics into ice cream at the levels of 0.1% and 0.4% (w/w) resulted in significant changes in the pH, total acidity, and color of the samples. The most prominent outcomes of phenolic incorporation were sharp improvements in antioxidant and antidiabetic activities as well as the phenolic content of ice creams. Replacement of pomegranate seed oil by milk fat at the levels of 2.0% and 4.0% (w/w) increased the conjugated fatty acid content. However, perception of oxidized flavor increased with the additional seed oil. When one considers the functional and nutritional improvements in the enrichment of the ice cream together with overall acceptability results of the sensory analysis, then it follows from this study that ice creams enriched with pomegranate peel phenolics up to 0.4% (w/w) and pomegranate seed oil up to 2.0% (w/w) could be introduced to markets as functional ice cream. Enrichment of ice creams with pomegranate by‐products might provide consumers health benefits with striking functional properties of punicalagins in pomegranate peel, and punicic acid in pomegranate seed oil.     

Characterization of the Red Layer and Pericarp of Processing Tomato using Magnetic Resonance Imaging

Abstract: The characteristics of tomato pericarp are closely associated with peelabililty, an important quality attribute of processing tomatoes. Different types of tissue exist in the pericarp of tomato. The outermost region of the pericarp, the red layer, is removed with the skin during peeling. This study investigated the morphological features and tissue properties of red layer and pericarp for 3 processing tomato cultivars using magnetic resonance imaging (MRI). The red layer can be visualized in MR images with T₂ weighting, indicating the red layer has different properties compared to the rest of the pericarp region. Tomatoes were imaged with a set of MRI sequences with signal intensity dependent on different water proton properties. Principal component analysis (PCA) of the statistical features revealed clustering of fruit by cultivar. The spatial distribution of cultivars in the PCA score plot followed their rank of peeling performance. MRI demonstrated potential as a nondestructive method to characterize tomato pericarp and evaluate the peelability of processing tomatoes. Practical Application: Peelability of tomatoes affects the quality of value‐added whole peel and diced tomato products. The properties of the pericarp of tomato are directly related to the peelability of tomatoes. MRI provided a fast and nondestructive method to characterize the properties of tomato pericarp. The result of this work gives insight into the correlation between tomato pericarp characteristics and peelability.     

禽蛋品质无损检测及分级技术研究进展

禽蛋产业是世界农业产业的重要组成部分,禽蛋产业也是我国农业的关键组成,是关系民生和社会稳定的重要产业。目前,禽蛋企业主要是依靠人工挑选及分级,劳动强度大且效率低,检测精度无法保证。因此,禽蛋品质的快速无损检测及分级研究对产业发展具有重要意义。本文根据现有研究,针对禽蛋无损检测中广泛使用的声学检测、机器视觉检测、光学检测等方法的研究现状进行综述,阐明不同的无损检测方法在实际的禽蛋挑选及分级中的适用性。其中,声学检测主要应用于禽蛋表面的裂纹检测与分级;机器视觉技术主要应用于禽蛋的大小、颜色等外观参数检测;光学特性检测主要是用于禽蛋新鲜度等内部品质检测。本文有望为禽蛋产业智能化分级技术的发展提供一定的理论支持。     

Valorisation of low quality edible oil with tomato peel waste

The aim of this study is to enrich edible oils with carotenoids and lycopene from tomato purée or tomato peel, an industrial tomato waste. These tomato derivatives were incorporated in refined olive oil, extra virgin olive oil and refined sunflower oil. The incorporation of peel enhanced the concentration of β-carotene and lycopene more than tomato purée. Furthermore, the incorporation of both tomato purée and peel induced better thermal stability of the refined olive oil compared to extra virgin oil and sunflower oil. A decrease on total phenols as well as some prooxidant activity account for this, when tomato purée was incorporated. In our oil preparations, rutin and naringenin, as flavonoids coming exclusively from tomato purée or peel, were detected. The enrichment of oils with tomato carotenoids and lycopene, in particular low quality oils like refined olive oils, might be an alternative approach to elaborate new functional foods.     

微波辅助提取-气相色谱-质谱联用快速分析花椒挥发油

建立微波辅助提取-气相色谱-质谱联用快速分析花椒挥发油的方法。采用微波辅助提取-水蒸气蒸馏法(MAE-SD)提取挥发油,正交试验设计优化微波辅助提取条件,气相色谱-质谱联用分析挥发油的化学成分和理化性质,同时将微波辅助提取与传统水蒸气蒸馏法进行比较。结果表明：MAE-SD的最佳工艺为微波功率400W、加水量15mL/g、浸泡30min,提取20min;经GC-MS分析,分离得到137种成分,质谱鉴定相似度在90%以上的化合物59种;根据峰面积归一法,相对含量较高的成分有桧萜(3.72%)、β-月桂烯(8.34%)、枞萜(15.15%)、松油烯(3.65%)、桉树脑(6.25%)、α-蒎烯(4.95%)、β-芳樟醇(3.05%)、4-萜品醇(10.48%)、松油醇(3.55%)、α-松油醇酯(4.09%);与水蒸气蒸馏法相比,挥发油的成分种类和理化性质接近,但相对含量存在一定差异。MAE-SD可快速高效提取挥发油类成分,联合GC-MS可对挥发油进行快速分析。     

Extraction and characterization of pectin from pomelo peel and its impact on nutritional properties of carrot jam during storage

Pectin was extracted using 0.1 N HCl at 90 °C for 120 min at pH 1.5 and 2.0 from pomelo peel and characterized in this study. Influence of various concentrations of extracted pomelo peel pectin on physicochemical, bioactive compounds, color, and sensory attributes of carrot jam during storage was also studied. Pectin extracted at pH 2.0 had higher ash content, equivalent weight, and total anhydrouronic acid content than that extracted at pH 1.0. Extracted pomelo peel pectin was categorized as high‐methoxyl pectin based on the degree of esterification. The β‐carotene and total phenol content were increased in jam after 90 days of storage. Ascorbic acid content decreased with increasing storage period. Jam prepared using commercial pectin had higher ΔE values than jam prepared using pomelo peel pectin. Physico‐chemical properties were influenced by pectin concentrations and storage time. Overall acceptability was similar for all samples on the basis of sensory evaluation. The results showed that pomelo peel might be used as a rich source of pectin and pomelo peel pectin could be used as an alternative to commercial pectins for carrot jam preparation.

Practical applications

Pectin is one of the main ingredients for jam and jelly making. Citrus fruits are main sources of pectin. Usually pomelo peels are discarded as waste materials. However, it could be a good source of pectin. In this article, pectin was extracted from pomelo peel and its application was observed as carrot jam during storage. Therefore, it can be concluded that extraction of pectin from pomelo peel might be used as an alternative to commercial pectin for carrot jam preparation.     

采后橘油诱导及振动胁迫对贮藏期锦橙果皮油胞病的影响

以果皮塌陷指数和变色指数为测定指标,研究橘油及振动胁迫处理对锦橙果皮油胞病的影响。结果表明：随橘油体积分数增大果皮油胞病逐渐加重,并以100%橘油处理对锦橙果皮油胞病的诱导效果最明显;锦橙果皮油胞病发病程度随着振动胁迫强度增大而加重,其中500r/min的诱导效果最显著。另外,在橘油和振动胁迫处理后的果实在不同温度下贮藏时,发现20℃贮藏的锦橙果皮油胞病最为严重,0℃冷害温度也能加剧果实油胞病的发生,5℃贮藏的锦橙果皮油胞病最轻微。研究结果为进一步研究柑橘油胞病的发生机理及防控措施提供理论依据。     

近红外光谱无损检测在食用油脂分析中的应用研究进展

近红外光谱技术作为一种具有样品前处理简便、快速高效、可以实现多组分同时分析等优点的新型无损分析技术,在食用油脂分析领域扮演着重要角色。对近10年来近红外光谱技术在食用油脂无损检测中的应用进行了总结,概述了近红外光谱技术的分析类型,在食用油脂和食用油脂原料分析方面的应用。通过结合化学计量学方法,近红外光谱技术可以实现不同种类食用油脂的快速鉴别分析,食用油脂的各项理化指标(如游离脂肪酸的含量、碘值、酸值、过氧化值、皂化值等)的快速检测,食用油脂无损掺假检测,食用油脂原料(如玉米、棉籽、油菜籽等)含油量的无损分析。此外,针对当前食用成品油快速无损分析过程中的难题对未来该领域的研究方向进行了展望,以期近红外光谱技术在食用油脂无损分析领域得到更广泛的应用。     

Effects of micronisation on the characteristics and physicochemical properties of insoluble fibres

The effects of micronisation on the characteristics and physicochemical properties of (a) an insoluble fibre‐rich fraction (IFRF) prepared from orange peel and (b) cellulose were studied and compared. The results showed that micronisation techniques such as ball milling, jet milling and high‐pressure micronisation could effectively (P < 0.05) reduce particle sizes to microscale, decrease the bulk density and improve the physicochemical properties (water‐holding capacity, swelling capacity, oil‐holding capacity, cation exchange capacity and glucose adsorption capacity) of IFRF and cellulose to different extents (up to 25‐fold). After micronisation the inhibitory effects of these insoluble fibres towards α‐amylase and pancreatic lipase were significantly increased (up to 5.8‐ and 7.8‐fold respectively) and a redistribution of some fibre components from insoluble to soluble fractions was observed. It was concluded that these micronisation treatments, especially high‐pressure micronisation, could effectively improve the functionalities of IFRF and cellulose, which might then be used as potential fibre‐rich ingredients in functional food applications. Copyright © 2006 Society of Chemical Industry     

Phytochemicals in fruits of two Prunus domestica L. plum cultivars during ripening

BACKGROUND: Plums are a rich source of nutritive and bioactive compounds. The objective was to evaluate the impact of fruit tissue (flesh and peel), ripening stage and cultivar on the composition of phytochemicals in plums (Prunus domestica L.) and to analyse the relation between total antioxidant activity (TAA) and the measured variables. RESULTS: The content of total sugars and total organic acids was higher in flesh but total phenolic content (TPC) and TAA was statistically higher in plum peel. The composition of sugars depended on fruit tissue, ripening stage and the cultivar. Ripening and fruit tissue affected the composition and concentrations of organic acids. TPC of ‘Haganta’ peel increased during ripening but there was no significant time trend for ‘Jojo’ peel and flesh of both cultivars. The composition of phenolics in peel depended on the cultivar, but in flesh on the cultivar and ripening. Ripening resulted in increased total anthocyanins and TAA in peel. TAA_peel was positively correlated with TPC_peel, total anthocyanins_peel, cyanidin 3‐glucoside_peel and peonidin 3‐rutinoside_peel in the cultivar ‘Haganta’. CONCLUSION: The composition of phytochemicals in P. domestica fruit depends on fruit tissue, ripening stage and the cultivar. Peel contributes to the TAA on average 20 times more than flesh. © 2012 Society of Chemical Industry     

A feature-selection algorithm based on Support Vector Machine-Multiclass for hyperspectral visible spectral analysis

Quality and safety of foods is one of the world’s top topics. Using high-precision spectral devices is a main technology trends by its high accuracy and nondestructive of food inspection, but the common obstacle is how to extract informative variables from raw data without losing significant information. This article proposes a novel feature selection algorithm named Support Vector Machine-Multiclass Forward Feature Selection (SVM-MFFS). SVM-MFFS adopts the wrapper and forward feature selection strategy, explores the stability of spectral variables, and uses classical SVM as classification and regression model to select the most relevant wavelengths from hundreds of spectral data. We compare SVM-MFFS with Successive Projection Analysis and Uninformative Variable Elimination in the experiment of identifying different brands of sesame oil. The results show that SVM-MFFS outperforms in accuracy, Receiver Operating Characteristic curve, Prediction and Cumulative Stability, and it will provide a reliable and rapid method in food quality inspection.     

Utilisation of orange peel in the production of α-terpineol by Penicillium digitatum (NRRL 1202)

The use of orange peel oil in the biotransformation of d-limonene was investigated. The physicochemical properties of cold-pressed orange peel oil, used in this investigation were determined to define its identity. The chemical composition of orange peel oil was determined by using GC/MS. Monoterpene compounds amounted to 98.0%, followed by aldehdyde components 1.09%. The main component of orange peel oil was d-limonene, which represented 96.1%, of the total content. A strain of Penicillium digitatum NRRL 1202 was used to carry out the biotransformation of d-limonene to α-terpineol. Two different media, malt yeast broth (MYB) and malt extract broth (MEB) were used. It was found that the highest bioconversion of d-limonene into α-terpineol was obtained by using MYB medium (pH 6.1).     

Adulteration detection of argan oil by inductively coupled plasma optical emission spectrometry

The singularity of the trace element profile of argan oil has been demonstrated by means of inductively coupled plasma optical emission measurement in combination with different chemometric approaches. The ability of multivariate analysis methods; such as hierarchical cluster analysis (HCA), principal component analysis (PCA), classification trees using Chi-squared Automatic Interaction Detector (CHAID) and discriminant analysis (DA) to achieve edible oils classification based on its type or variety from their elemental content have been investigated. The calculations were performed using 16 variables (contents of Na, Mg, Al, K, Ca, Ti, Fe, Co, Ni, Cu, Zn, Cd, Pr, Sm, Er and Bi at μg g⁻¹ level determined by ICP-OES). HCA is able to differentiate sunflower oil samples from the rest, however the discrimination of argan oil from olive, seeds and soya oils based on their different trace element composition is hard to achieve. The PCA analysis shows three different classes in the multidimensional space (PC1-3) representing sunflower, argan and a third group comprising olive, seeds and soya oils. CHAID method allows separating the entire vegetable oil dataset, providing a correct re-substitution rate of 94.12% for argan oil using only the concentration of K. DA performed using the same variables, provides also an acceptable average accuracy results of 93.65%, by the re-substitution method. DA has been successfully applied to the analysis adulterated argan oil by addition of cheaper vegetable oils.     

Measuring Netted Muskmelon Maturity by Delayed Light Emission

Netted muskmelon fruits of Hale's Best, Magnum 45 and Saticoy cultivars in 6 different maturity classes, from immature to mature were examined. Maturity class was based on days after anthesis. The melons were evaluated for differences in delayed light emission (DLE) measurements and physical and chemical properties that relate to maturity. DLE, firmness, and chlorophyll decreased with increasing maturity, whereas Hunter a and soluble solids increased. DLE correlated highly (r =?0.94) with a calculated maturity index, indicating that DLE could be used as a nondestructive technique for measuring the maturity of netted muskmelon.     

蓝莓皮提取物及油脂凝胶化对水飞蓟油氧化稳定性的影响

本文预期通过添加蓝莓皮提取物和油脂凝胶化来提高水飞蓟油的氧化稳定性,基于过氧化值(POV)和硫代巴比妥酸反应物(TBA)等化学方法与电子鼻技术和核磁共振技术(_¹H NMR)相结合,监测水飞蓟油氧化稳定性、气味和脂肪酸、色泽等变化。结果表明,蓝莓皮提取物能够有效的抑制水飞蓟油的氧化且具有剂量依赖关系,0.06%的蓝莓皮提取物对水飞蓟油的氧化抑制作用最佳;蓝莓皮提取物会影响水飞蓟油的气味但不影响其色泽;蓝莓皮提取物对水飞蓟油凝胶的色泽和气味均无影响,但制备成水飞蓟油脂凝胶明显提高了水飞蓟油氧化稳定性。     

青柠果皮精油蒸馏工艺优化及香气成分分析

目的:研究青柠果皮精油提取工艺及性质,为青柠果皮的综合利用提供数据。方法:以青柠果皮为原料,通过压榨法提取其精油粗产品,后经分子蒸馏技术对其进行分离纯化,以总轻馏分得率为指标,考察蒸馏温度、刮板转速、进料速度、蒸馏压力4个单因素对青柠果皮精油提取的影响,通过正交实验优化青柠果皮精油提取工艺,并用气质联用仪(GC/MS)分析青柠果皮精油香气成分组成。结果:青柠果皮精油的最佳提取工艺:蒸馏温度30℃,刮板转速400 r/min,进料速度0.25 L/h,蒸馏压力15 Pa,其总轻馏分得率为76.10%±0.29%;GC/MS结合保留指数对纯化青柠果皮精油进行香气成分分析,共鉴定55种化合物,主要包括柠檬烯(36.585%)、γ-松油烯(12.077%)、α-松油醇(8.407%)、萜品油烯(7.867%)、α-松油烯(5.777%)等。结论:优化了分子蒸馏提取青柠果皮精油工艺,并从香气成分中鉴定出55种化合物。