基于深度信念网络的苹果霉心病病害程度无损检测

针对现有霉心病无损检测只能检测出有无病害,无法对病害程度进行判断的问题,研究并提出一种基于深度信念网络(deep belief net,DBN)的无监督检测模型。该模型由多层限制玻尔兹曼机(restricted Boltzmann machine,RBM)网络和1层反向传播(back propagation,BP)神经网络组成,RBM网络实现最优特征向量映射,输出的特征向量由BP神经网络对霉心病病害程度分类。对225个苹果样本在波长200~1 025 nm获取其透射光谱后,根据腐烂面积占横截面比例将霉心病害程度分为健康、轻度、中度和重度4种,分别用150个和75个样本作为训练集和测试集,以全光谱数据和基于连续投影算法提取的特征波长数据为输入构建病害程度判别模型,并比较DBN模型与偏最小二乘判别分析、BP神经网络和支持向量机模型的识别效果,实验结果表明,DBN模型病害判别准确率达到88.00%,具有较好的识别效果。     

基于透射光谱的苹果霉心病多因子无损检测

针对目前苹果霉心病难以检测的问题,提出一种基于透射光谱的苹果霉心病多因子无损检测方法,通过融合多波段透射光谱与苹果直径,构建苹果霉心病判别模型,实现了苹果霉心病无损检测。搭建光谱测试范围在200～1 025 nm的透射光谱采集平台,实验获取232 个苹果样本的透射光谱数据,采用游标卡尺获得苹果直径数据。采用杂散光校正,非线性校正对苹果透射原始光谱进行预处理,选取与霉心病发病相关的12 个波段透射光强值,结合苹果的直径进行主成分分析,将分析的结果作为自变量,建立苹果霉心病Fisher判别模型。经过异校验验证,模型总体识别率为93.1%,而仅采用透射光谱构建的模型识别率为91.37%。结果表明,基于透射光谱与直径结合的多因子检测方法可实现苹果霉心病的准确判定,为苹果霉心病的快速、无损检测提供可行思路。     

基于电子鼻表征霉心病苹果特征气味及无损检测模型建立

为探究电子鼻检测技术对霉心病苹果的判别效果,以富士健康苹果和霉心病苹果为试材,基于SIMCA软件对采集的不同病变程度霉心病苹果的电子鼻信息进行表征,基于SPSS 23.0软件建立霉心病苹果Fisher函数、多层感知器神经网络(muhilayer perceptron neural network,MLPNN)和径向基函...     

基于傅里叶近红外光谱和电子鼻技术的苹果霉心病无损检测

为研究傅里叶近红外光谱技术(Fourier transform near infrared spectroscopy,FT-NIRS)和电子鼻技术分别结合化学计量学方法对苹果霉心病的判别效果,以“红富士”霉心病苹果和健康苹果为试材,利用近红外光谱技术,基于主成分分析建立Fisher判别和多层感知器(multi-layer perceptron,MLP)神经网络模型;同时利用电子鼻技术分别结合Fisher判别、MLP神经网络和径向基函数神经网络3种化学计量学的方法建立判别模型。根据建模集和验证集的预测准确率综合考虑,基于主成分分析建立的MLP神经网络模型和电子鼻结合MLP神经网络模型对苹果霉心病的判别效果最好,验证集中的正确判别率分别达到87.7%和86.2%。说明电子鼻和近红外光谱技术均可以较好地判别苹果霉心病。     

Making best use of available residue data for acute intake assessment

Risk assessment for pesticide residues in food has previously concentrated on chronic intake, probably with the assumption that if the chronic intake is acceptable, acute intake will also be acceptable. Data generation is expensive so we should extract, where possible, information useful for acute intake estimation from supervised residue trials. Residues in individual units of fruit or vegetables are more variable than the residues in composite samples and the distribution in individual units is probably best approximated by a lognormal distribution, but further evidence is needed. Theory provides a method for calculating the variability of replicate composite samples and applying it to individual units. The expected residue in the 95th or 99th percentile single fruits may then be calculated. An example for folpet residues in apples showed that the 95th and 99th percentile apples would contain 1.8 x and 2.3 x the residue in the composite sample, respectively. For abamectin in apples the 95th and 99th percentile factors were 6.7 and 15, respectively. The 95th and 99th percentile factors for azinphos-methyl in apples, based on single apple analysis, were 1.7 and 2.1, respectively.     

Incidence of bitter pit in relation to the calcium content of apples: Calcium distribution in the fruit

The distribution of calcium at harvest, its subsequent redistribution within the fruit during storage in air at 2.8°C and bitter pit development in samples of Cox's Orange Pippin apples picked at intervals during September and October were investigated. The distribution of calcium in the fruit changed on the tree and during storage. The percentages of pitted apples, assessed in January, were poorly related to calcium concentrations in the whole fruit or in any fruit zone at harvest. Redistribution of calcium from the mid and outer cortical tissues to the core zone was followed, at longer intervals over successive picks, by the appearance of bitter pit lesions. The earliest-picked sample was less affected by bitter pit than samples picked later in September. The least bitter pit occurred in samples picked in October, after the climacteric rise in respiration, and these fruits were apparently less subject to fluctuations in calcium concentrations during storage.     

Quantitative analysis of mycoflora on commercial domestic fruits in Japan

A comprehensive and quantitative analysis of the mycoflora on the surface of commercial fruit was performed. Nine kinds of fruits grown in Japan were tested. Overall fungal counts on the fruits ranged from 3.1 to 6.5 log CFU/g. The mean percentages of the total yeast counts were higher than those of molds in samples of apples, Japanese pears, and strawberries, ranging from 58.5 to 67.0%, and were lower than those of molds in samples of the other six fruits, ranging from 9.8 to 48.3%. Cladosporium was the most frequent fungus and was found in samples of all nine types of fruits, followed by Penicillium found in eight types of fruits. The fungi with the highest total counts in samples of the various fruits were Acremonium in cantaloupe melons (47.6% of the total fungal count), Aspergillus in grapes (32.2%), Aureobasidium in apples (21.3%), blueberries (63.6%), and peaches (33.6%), Cladosporium in strawberries (38.4%), Cryptococcus in Japanese pears (37.6%), Penicillium in mandarins (22.3%), and Sporobolomyces in lemons (26.9%). These results demonstrated that the mycoflora on the surfaces of these fruits mainly consists of common pre- and postharvest inhabitants of the plants or in the environment; fungi that produce mycotoxins or cause market diseases were not prominent in the mycoflora of healthy fruits. These findings suggest fruits should be handled carefully with consideration given to fungal contaminants, including nonpathogenic fungi, to control the quality of fruits and processed fruit products.     

基于机器视觉的苹果在线分级

通过CCD相机动态采集苹果两个面的实时图像,提出了泛洪填充+自适应Ostu阈值分割算法提取苹果的轮廓,采用最小外接圆法对苹果上表面图像进行处理得到苹果果径,采用最小外接矩形法对苹果侧表面图像进行处理提取苹果果形特征;将图像进行RGB到HSV空间转换,提取苹果的着色度、果锈,以及疤痕特征,采用基于改进粒子群算法的SVM决策树的分类方法进行苹果的分级。结果表明,该方法对特级果、一级果、二级果和等外果的识别准确率分别达96%,94%,98%,98%,分级速率达4个/s,可以满足苹果在线分级的要求。     

TWIST TEST FOR MEASURING FRUIT FIRMNESS

A new test for measuring in-situ crushing strength of flesh of a range of fruits and other crops is described. The device consists of a blade on a spindle, which is pushed into the fruit and rotated about the axis of the spindle. The resisting moment is measured by an offset arm arrangement. The tester can measure fruit properties in-situ at any depth, including the core of the fruit. This has advantages for fruits that ripen from the centre, or where internal properties are more important than those close to the surface. Each full test can be completed in under 15 s. The tester is easier to use and more reliable than a conventional penetrometer. Some typical experimental results conducted on kiwifruit and apples harvested at various stages of growth and maturation are presented.     

Apple quality,storage, and washing treatments affect patulin levels in apple cider

Patulin is a mycotoxin produced primarily by Penicillium expansum, a mold responsible for rot in apples and other fruits. The growth of this fungus and the production of patulin are common in fruit that has been damaged. However, patulin can be detected in visibly sound fruit. The purpose of this project was to determine how apple quality, storage, and washing treatments affect patulin levels in apple cider. Patulin was not detected in cider pressed from fresh tree-picked apples (seven cultivars) but was found at levels of 40.2 to 374 microg/liter in cider pressed from four cultivars of fresh ground-harvested (dropped) apples. Patulin was not detected in cider pressed from culled tree-picked apples stored for 4 to 6 weeks at 0 to 2 degrees C but was found at levels of 0.97 to 64.0 microg/liter in cider pressed from unculled fruit stored under the same conditions. Cider from controlled-atmosphere-stored apples that were culled before pressing contained 0 to 15.1 microg of patulin per liter, while cider made from unculled fruit contained 59.9 to 120.5 microg of patulin per liter. The washing of ground-harvested apples before pressing reduced patulin levels in cider by 10 to 100%, depending on the initial patulin levels and the type of wash solution used. These results indicate that patulin is a good indicator of the quality of the apples used to manufacture cider. The avoidance of ground-harvested apples and the careful culling of apples before pressing are good methods for reducing patulin levels in cider.     

SCALE TRANSLATIONS OF FIRMNESS TESTS ON FRUITS

In many fruits and vegetables, it is desired to replace destructive firmness measurement methods by nondestructive ones. The inevitable question is to what degree do two firmness measurement methods agree? The present article proposes a new approach for method comparison in firmness tests of fruits, by optimal translation of the readings taken on the scale of one test, to the scale of another test and vice versa. The proposed scale translation mode is based on minimizing the sum of squares of the differences between the absolute values of the Fast Fourier Transform (FFT) series, derived from the readings of the compared measurement methods. The line taken is illustrated by a comparative study on a large sample of Red Delicious apples, assessing the performance of a nondestructive fruit firmness sensor versus the conventional destructive test which measures the applied piercing force on the fruit by a penetrometer.     

2019年重庆市水果类监督抽检情况分析

目的 研究2019年重庆市水果类监督抽检结果, 分析新鲜水果类食品存在的主要食品安全风险。 方法 整理汇总了重庆市市场监督管理局2019年发布的44个食品安全抽检信息通告, 提取食用农产品中新鲜水果类的数据, 对不合格样品进行分析。结果 2019年重庆市共抽检了3785批次水果类食用农产品, 包括了29个水果品种。不合格数37批次, 不合格率为0.98%, 包含柑、橘,香蕉,苹果。柑、橘不合格率为2.08%, 不合格项目是丙溴磷; 香蕉不合格率为15.98%, 不合格项目是吡唑醚菌酯; 苹果不合格率为0.11%, 不合格项目是敌敌畏。其余水果品种未发现不合格样品。结论 2019年重庆市水果类食品安全总体形势良好, 但应警惕柑、橘水果中的丙溴磷和香蕉中的吡唑醚菌酯的违规使用。     

食品中展青霉素的研究进展

展青霉素是由曲霉菌和青霉菌等真菌产生的次级代谢产物, 是广泛存在于水果(特别是霉变水果)、水果制品(果汁、果酱、果脯等)及谷物等食品中的天然污染物, 可以通过食物摄取的方法进入机体。展青霉素不仅具有免疫毒性和致畸性, 而且对人体多种器官都有毒害作用。展青霉素污染的食品(尤其是水果及水果制品)不仅会对人类健康造成严重的威胁, 而且会严重危害我国经济和食品加工业的发展。为了探讨食品中展青霉素的研究进展, 本文主要从展青霉素的基本性质、毒性与危害、检测方法和脱除方法等部分进行论述, 以期为展青霉素的毒性研究提供的理论参考。     

INELASTICITY AND BRUISING OF CHERRIES

Cherries of three varieties were compressed between two plates in the loadingunloading test to determine the energy dissipated during the test. After compression, the bruise volume of the deformed fruit was determined. Bruise resistance coefficient (BRC) and bruise sensitivity (BS) were evaluated in a similar way as for apples. It is shown that, contrary to the results for apples, the BRC and BS values depend on the compression ratio in a more complicated way for cherries than for apples. The principal differences in bruise sensitivity were observed for different cherry varieties. These differences cannot be explained by the macroscopic mechanical properties of the fruits only.     

Low oxygen treatment prior to cold storage decreases the incidence of bitter pit in ‘Golden Reinders’ apples

BACKGROUND: The effect of subjecting ‘Golden Reinders’ apples to a low O₂ pre‐treatment (LOT; 1–2% O₂) was evaluated as a strategy to decrease the rate of bitter pit (BP) incidence after standard cold storage (ST). Immediately after harvest, apples were stored for 10 days at 20 °C under low O₂. Thereafter, apples were cold‐stored (0–4 °C) for 4 months and changes were monitored in terms of BP incidence, fruit quality traits and mineral element concentrations. RESULTS: After 4 months cold storage, LOT apples presented a 2.6‐fold decrease in the rate of BP incidence (14%) versus the values obtained for standard cold‐stored fruits (37% BP incidence). LOT increased flesh firmness, total soluble solids and titratable acidity as compared to the quality traits determined for cold‐stored fruits. Lower cortex Ca and Mg concentrations as compared to ST apples were determined in association with LOT, 2 months after cold storage. CONCLUSION: Application of a LOT prior to cold storage may be a promising strategy to reduce the incidence of BP and preserve fruit quality, which should be further investigated. Copyright © 2009 Society of Chemical Industry     

一次性灌胃不同水果汁对大鼠外周血抗氧化力影响的研究

目的:观察不同抗氧化力水果汁对大鼠外周血抗氧化活性的影响。方法:以FRAP法测定水果汁的抗氧化活性,以灌胃法观察不同水果制汁后对大鼠外周血抗氧化活性的影响。取山楂、猕猴桃、石榴、草莓、苹果、梨果肉制汁后灌胃,连续动态观察大鼠外周血抗氧化力的变化。结果:测定的6种水果汁抗氧化活性排序依次为山楂、猕猴桃、石榴、草莓、红香蕉苹果、水晶梨。灌胃4g抗氧化力较强的山楂、猕猴桃、石榴制汁,大鼠外周血抗氧化力均显著增强,与对照组相比有显著性差别(P<0.01);抗氧化力较弱的红富士苹果和水晶梨制汁灌胃后外周血抗氧化力无变化;灌胃2g水果制汁后变化趋势与4g相同,但与对照组比较无显著差别。结论:在体外具有较强抗氧化力的水果汁对大鼠外周血抗氧化力影响较为显著,但抗氧化力较弱水果汁该作用较弱。     

Redistribution of minerals in apple fruit during storage: Effects of storage temperature,varietal differences and orchard management

Transverse calcium redistribution from the cores to the outer zones of the fruit was interrupted for a short period when calcium was imported by the cores of both Cox and Spartan apples, especially at 3.5°C. Bitter pit lesions developed in mid and outer cortical tissues of Cox fruit stored at 3.5°C 2 to 4 weeks after calcium concentrations in these zones were reduced. Redistribution of magnesium from the outer zones to the cores of Spartan apples occurred during storage at 3.5°C but was inhibited at 0°C. Redistribution of magnesium in Cox's Orange Pippin apples was mainly from inner cortex to the core and outer zones at 3.5°C and from central to outer zones at 0°C, but immediately low temperature breakdown become evident at 0°C, magnesium was transferred from the peel and core to the affected zones. The redistribution of phosphorus to the cores, which occurred in Spartan apples (resistant to low temperature breakdown) stored at either 3.5°C or 0°C was barely evident in Cox fruit (susceptible to low temperature breakdown) stored at 3.5°C and did not occur at 0°C. Irrigated grass compared with overall herbicide soil management increased the proportion of calcium in the core zones of both Cox and Spartan apples and the proportion of magnesium in the core zone of Spartan apples at harvest. Irrigated grass management also increased the rate of calcium redistribution in Cox and Spartan fruit during storage and altered magnesium redistribution in Spartan apples stored at 0°C.     

RADIO FREQUENCY PULSE APPLICATION FOR HEATING UNIFORMITY IN POSTHARVEST CODLING MOTH (LEPIDOPTERA: TORTRICIDAE) CONTROL OF FRESH APPLES (MALUS DOMESTICA BORKH.)

A radio frequency (RF) treatment, with a pulse mode to increase heating uniformity, was examined as a potential quarantine treatment against fifth instars of the codling moth, Cydia pomonella L. (Lepidoptera: Tortricidae), in apples, Malus sylvestris L. var. domestica (Borkh.) Mansf., intended for export to Japan. Apples were exposed in water baths to 27.12‐MHz RF energy at 12 kW with a pulse mode of 30 s‐on/30 s‐off for different durations. The temperature uniformity was determined by measurements at 12 sites evenly spaced at two depths in the fruit. The most promising exposure time was 29 min. The efficacy of the treatment with the pulse mode was examined against the codling moth larvae by using exposures between 27 and 30 min and up to 30 min of holding time in bath after treatment. The treatment that killed all larvae with the least amount of energy was the 29‐min exposure with 50‐min holding time. This treatment was appraised for fruit quality in “Delicious” apples. Some injury was observed when treated fruits were removed from 1C storage after 30 days. When these fruits were held at 25C for 1 week, all were too damaged to evaluate for fruit quality. Although pulse mode increased heating uniformity in the fruit, the thermal requirements to control codling moth larvae may exceed the injury threshold of the fruits.     

采后1-MCP和MAP处理对‘红富士’苹果冷藏和货架期品质的影响

对‘红富士’苹果进行1.0 μL/L 1-甲基环丙烯（1-methylcyclopropene,1-MCP）和自发气调包装（modified atmosphere package,MAP）处理,继而进行0 ℃冷藏和20 ℃货架贮藏。结果表明：贮藏期间,‘红富士’苹果果实硬度和可滴定酸含量下降,可溶性固形物含量升高,虎皮病和果心褐变增多。1-MCP处理能较好维持冷藏期间‘红富士’苹果果实硬度和可溶性固形物含量,降低了包装内CO2和乙烯含量。同时,1-MCP明显降低了冷藏期间虎皮病发病指数、果心褐变指数以及果柄端果肉褐变率,显著抑制果皮α-法尼烯及共轭三烯的生成。1-MCP＋MAP结合使用可较好维持果实可滴定酸含量和果皮色泽、抑制果柄端果肉褐变。综合分析认为,1-MCP＋MAP处理能较好维持‘红富士’果实冷藏和货架期间的品质,并显著抑制果实虎皮病的发生。