甜柿货架期的近红外光谱定性判别

通过近红外漫反射光谱技术对甜柿的货架期进行了定性判别研究,运用不同光谱预处理方法和不同波段选择,发现在1 100² 400 nm内,采用二阶导数结合标准正常化和去散射(SNVD)处理的光谱预处理方法最好。判别模型的正确分类率达到97.8%2 400 nm内,采用二阶导数结合标准正常化和去散射(SNVD)处理的光谱预处理方法最好。判别模型的正确分类率达到97.8%¹00%,预测准确率达到88.9%100%,预测准确率达到88.9%¹00%。因此,近红外光谱技术对甜柿货架期的检测具有应用价值。     

线椒货架期的近红外光谱定性判别

利用近红外漫反射光谱技术对线椒的货架期进行定性判别研究。实验以常温货架期1、3、5 d的线椒为研究对象,利用主成分分析法（PCA）建立近红外漫反射定性判别模型,在全光谱范围（400²500 nm）内比较了不同的光谱预处理方法结合不同散射和标准化方法对所建模型的影响。结果表明,采用全光谱下Log（1/R）+None光谱预处理方法建立的模型预测最好,该模型的交互验证相关系数(R_CV)为0.9455,交互验证误差（SECV）为0.1534,其正确分类率达95.56%¹00%,预测准确率达88.89%⁹7.78%,该模型能够准确地区分不同货架期的线椒鲜果。因此,近红外光谱技术为线椒货架期的鉴别提供了一种新方法。      

苹果货架期的近红外光谱定性分析

以嘎啦苹果为试材,使用ASD公司的FieldSpec3光谱仪在常温条件下进行近红外光谱采集,应用OPUS软件的快速比较法和电子称重数据对苹果样品的近红外光谱信息进行处理。结果表明,苹果样品在室内常温及通风条件下10d失重率即可达到5%;货架期苹果的近红外光谱在水分吸收峰1440nm和1936nm发生显著变化;快速比较法在使用二阶导数预处理方法可以准确、有效地进行定性鉴别。     

近红外光谱对贮藏期樱桃品质的定性判别

研究运用近红外光谱技术对贮藏期樱桃进行定性判别。实验的定标模型经过不同预处理和不同光谱波段条件的处理分析,得到在全光谱范围(408.8~2 492.8 nm)内,采用一阶微分结合去离散处理(SNV and D)的方法可以构建最优模型。该模型判别的正确分辨率为100%,预测准确率为90%~96.7%。实验说明,近红外光谱技术对贮藏期樱桃的检测具有适用性。     

基于电子鼻判别富士苹果货架期的研究

利用电子鼻对不同货架期内的富士苹果挥发性成分进行检测。通过雷达图和负荷加载(Loadings)分析研究主要传感器响应值的变化,利用主成分分析(PCA)、线性判别分析(LDA)模式判别方法进行数据分析。结果表明,第7、8号传感器在苹果常温货架期判别中起主要作用,而第2、7号传感器在苹果贮后货架期的判别中起主要作用。PCA、LDA方法均可准确判别常温不同货架期的苹果;与PCA相比,LDA方法可以更准确对不同贮后货架寿命苹果进行判别,并呈现出良好的集中性和单向趋势。因此,电子鼻快速判别不同货架期的苹果具有可行性。      

基于近红外漫反射光谱技术判别柿子品种和 贮藏期的研究

目的 通过近红外漫反射光谱技术建立了柿子不同品种和贮藏期的快速判别方法。方法 实验对置于冷库(0±0.5℃)贮藏20d、40d、60d的磨盘柿和阳丰甜柿的近红外光谱(400～2500nm)进行平滑处理、一阶倒数和标准正常化处理(SNV)处理,采用主成分分析法(PCA)建立判别模型。结果 在全波长范围内,不同品种定标模型的正确分类率达到100%;阳丰甜柿不同贮藏期的正确分类率达到97.78%;磨盘柿不同贮藏期的正确分类率达到98.89%。3个预测模型的累积准确率达到96.67%。结论 通过近红外漫反射光谱技术,判别不同品种的柿子并预测其贮藏期具有应用价值。     

基于近红外漫反射光谱技术判别柿子品种和贮藏期的研究

目的通过近红外漫反射光谱技术建立了柿子不同品种和贮藏期的快速判别方法。方法实验对贮藏冷库(0±0.5℃)20 d、40 d、60 d的磨盘柿和阳丰甜柿的近红外光谱(400~2500 nm)进行平滑、一阶倒数和标准正常化处理(SNV)处理,采用主成分分析法(PCA)建立判别模型。结果在全波长范围内,不同品种定标模型的正确分类率达到100%;阳丰甜柿不同贮藏期的正确分类率达到97.78%;磨盘柿不同贮藏期的正确分类率达到98.89%。3个预测模型的累积准确率达到96.67%。结论通过近红外漫反射光谱技术,判别不同品种的柿子并预测其贮藏期具有应用价值。     

近红外光谱技术在肉类定性鉴别中的研究进展

近红外光谱技术作为新型的快速绿色检测技术,在肉类工业中得到了广泛的应用。本文综述了近红外光谱技术在肉类定性鉴别中的研究进展,主要包括在肉的等级鉴别、品种鉴别、物种鉴别以及产地溯源、饲喂方式中的鉴别研究。肉的等级一般人工分为RFN、PFN、PSE、RSE四类,近红外光谱对肉的等级鉴别正确率在80%以上;对于同一物种不同品种肉的研究主要是在猪肉、牛肉上,主要通过多元定量校正方法或判别分析法来鉴别同一物种不同品种、不同年龄阶段的肉,且鉴别正确率大于95%;在不同物种之间的鉴别主要应用于鉴别猪肉、羊肉、牛肉、鸡肉等不同物种以及掺假肉,鉴别正确率在90%以上;在产地溯源、不同饲喂方式之间的鉴别,能够正确鉴别牧草和浓缩料饲喂的羔羊、母羊和人工饲喂的羔羊、不同地区的牛肉以及羊肉的产地溯源等,鉴别正确率大于83%。综上所述,近红外光谱在肉类定性鉴别中可行。     

近红外光谱用于鉴别苹果产地的研究

目的:探索近红外光谱定性分析技术鉴别苹果产地的可行性。方法:对天津、陕西和北京3个产地富士苹果品质进行了分析,比较了波段范围、导数处理和散射及标准化处理建立主成分分析结合最小二乘法产地鉴别模型。结果:在1100~1848 nm波段范围内采用一阶导数结合趋势变化法散射处理的光谱预处理方法最优,校正集的鉴别正确率为100%,校正交互验证误差(SECV)0.1245,交互验证相关系数(Rcv)0.9641,预测集的鉴别正确率为98.33%。结论:应用近红外光谱定性分析技术可以准确地、快速地追溯苹果产地的溯源。     

纳米SiOx保鲜果蜡对苹果贮藏性能的影响

以"乔纳金"和"红富士"为试材,研究了纳米SiOx保鲜果 蜡对两个品种苹果果实的呼吸强度、失重率、硬度和可溶 性固形物含量变化的影响。实验结果表明,纳米SiOx保 鲜果蜡有效抑制了果实的呼吸强度,显著降低了果实的 失重率,延缓了果实硬度和可溶性固形物含量的下降(p< 0.05),其对苹果货架期的延长已经与进口果蜡相近,某些 性能甚至优于进口果蜡。     

Quantitative assessment of the shelf life of ozonated apple juice

Sterile apple juice inoculated with S. cerevisiae ATCC 9763 (10³ CFU/mL) was processed in a bubble column with gaseous ozone of flow rate of 0.12 L/min and concentration of 33–40 μg/mL for 8 min. The growth kinetics of S. cerevisiae as an indicator of juice spoilage was monitored at 4, 8, 12 and 16 °C for up to 30 days. The kinetics was quantitatively described by the primary model of Baranyi and Roberts, and the maximum specific growth rate was further modeled as a function of temperature by the Ratkowsky type model. The developed model was successfully validated for the microbial growth of control and ozonated samples during dynamic storage temperature of periodic changes from 4 to 16 °C. Two more characteristic parameters were also evaluated, the time of spoilage of the product under static temperature conditions and the temperature quotient, Q ₁₀. At lower static storage temperature (4 °C), no spoilage occurred either for unprocessed or ozone-processed apple juice. In the case of ozone-processed apple juice, the shelf life was increased when compared with the controls, and the Q ₁₀ was found to be 7.17, which appear much higher than that of the controls, indicating the effectiveness of ozonation for the extension of shelf life of apple juice.     

Clarification, preservation, and shelf life evaluation of cashew apple juice

Cashew apples are tropical fruits rich in sugars, minerals, and vitamin C. In spite of having high nutritional value, neither the fresh cashew apples nor the juice is consumed due to astringency. In the present investigation an attempt was made to reduce the astringency without affecting the nutrient quality of the juice. The clarifying agent, sago at a concentration of 2 g/L, has decreased the tannins by 42.85% but the respective sample’s visual clarity is only 94%. The same clarifying agent with the same concentration along with sterile filtration has decreased the tannins by 41.75% with improved visual clarity of 96%. This clarified juice sample was treated with chemical preservatives and the quality of the juice was assessed periodically up to 4 months. The shelf life of juice treated with citric acid and benzoic acid at 0.1 g/L each and stored at 4°C was prolonged up to 90 days.     

Advances in the use of white light on broccoli and kale postharvest shelf life

In this work, the effect of irradiation with three different intensities of white light-emitting diodes (LED) on the quality and senescence of refrigerated broccoli and green and red kale was studied. A high increase in weight loss was observed in samples exposed to high (80 μmol m⁻² s⁻¹) and low (10 μmol m⁻² s⁻¹) LED intensity. Samples stored under mid-intensity (30 μmol m⁻² s⁻¹) significantly reduced the change of total color (∆E), hue angle, and lightness (L*) values. Broccoli florets and green kale subjected to mid-intensity illumination retained higher chlorophyll levels than the other treatments (P < 0.05), and about 30% more compared to the dark stored samples. These differences were even more evident in red kale. Mid-intensity illumination also markedly reduced sugar losses and improved carotenoid contents. As a whole, results show that the selected intensity of white light used for postharvest illumination has a key influence on treatment efficacy.Industrial relevancePostharvest shelf life of green vegetables is very limited and there is a need to use environmentally friendly tools to extend it. The use of white light during storage has been proven to be a clean and non-chemical methodology to delay vegetable senescence, but the appropriate illumination conditions to maximize the quality of unprocessed vegetables are still unknown. In the present work, the effect of different lighting conditions on the visual and nutraceutical quality of refrigerated broccoli and green and purple kale was studied, and the best condition was defined. The selected light intensity may be considered for fresh market storage.     

温度对冷藏富士苹果货架品质变化的影响

为了研究富士苹果在流通过程中的品质变化,以1-MCP处理后贮藏4个月的富士苹果为实验材料,0℃贮藏4个月后转移至模拟货架温度(5、10、15、20、25℃)下进行贮藏性试验,研究不同温度对感官品质和营养特性的影响并探讨富士苹果的品质随货架时间的变化规律。结果表明:以感官品质评价,影响富士苹果货架期品质的最主要因素是果皮的褪色,主要表现为花青苷含量和a值的下降,最有利于颜色保持的温度是5℃;25℃条件下综合品质下降最快;货架期8、16、24 d口味最佳温度分别为15、10、10℃,说明货架时间越长,要求温度越低。以营养品质评价,货架期间Vc和总酚含量呈下降趋势,果肉总黄酮含量先上升后下降,而果皮则一直处于下降的趋势,相对于果肉而言,果皮DPPH清除率在货架初期对温度不敏感,各温度之间无明显差别。以上结果说明货架期间低温有利于保持较高的营养品质,但是口味最佳时果实营养品质并不是最高。     

Effect of cutting and storage on sensory traits of cantaloupe melon cultivars with extended postharvest shelf life

Fresh cut cantaloupe melons (Cucumis melo L var reticulatus) from fruits with extended postharvest shelf life were analysed for changes in their volatile aroma compounds and polygalacturonase activity during storage. The total volatile aroma contents and the number of volatile compounds in fruits with extended shelf life were significantly less than those present in the traditional shelf life cultivar Mission. Esters were the major volatile compounds present in the fruits, and their concentrations decreased considerably with storage of the cut fruit for 24 h at 4 °C. Polygalacturonase activity was detected from measurements of the hydrolytic release of reducing groups after storage of the cut fruit for 3 days. Enzymatic activity decreased thereafter in all fruits. The results indicate a lack of correlation between the postharvest shelf life of whole cantaloupe and that of fresh cut fruit. © 2003 Society of Chemical Industry     

Different postharvest strategies to preserve broccoli quality during storage and shelf life: Controlled atmosphere and 1-MCP

Broccoli (Brassica oleracea var. italica) is a vegetable that requires the application of postharvest techniques to extend its marketability. Controlled atmosphere and 1-MCP treatments are most used to extend the shelf life of broccoli and reduce post-harvest deterioration. The aim of this study was to evaluate the visual, physicochemical and functional changes of broccoli head samples stored at 1–2 °C and 85–90% relative humidity (RH) in air (Control samples), under controlled atmospheres (10% O₂ and 5% CO₂) (CA samples) and treated with 1-MCP (0.6 μL/L). After storage all samples were maintained at 20 °C for 2 and 4 days, in order to assess their shelf life. The most suitable postharvest treatment to extend broccoli quality during storage and shelf life, in terms of maintaining the visual quality and reducing loss of health-promoting compounds, was achieved by storage under controlled atmosphere conditions. The use of 1-MCP reduced the loss of green colour and chlorophyll pigments, but only during cold storage not during shelf life at 20 °C.     

Using soy protein SiOx nanocomposite film coating to extend the shelf life of apple fruit

Preservation properties of soy protein isolate (SPI)/nano‐SiOx composite coatings to apple fruits were investigated. The sodium dodecyl sulfonate‐modified nano‐SiOx (SNS) particles were prepared by the ultrasonic method and the counter‐ion activation method, which products were designated as USNS and CSNS, respectively. The incorporation of CSNS particles was better than USNS to improve the preservation quality of the SPI film. The best conditions for the synthesis of the composite film were as follows: 10% SPI concentration, 0.3% nano‐SiOx dosage and coating time of 60 s. Under these conditions, the climacteric peak of apples was delayed to the fifth week. The apples also had better physiological indices than the control group. Nano‐SiOx particles were inlaid and evenly dispersed into the SPI film coatings. This work provides a simple CaCl₂ pre‐activation method to produce SPI film coatings with good dispersion of nano‐SiOx particles for further preservation application of fresh fruits.