To explore the effects of hot air (HA, 38 °C for 12 h) treatment on the phenylpropanoid metabolism in cherry tomatoes, phenylpropanoid metabolite levels and the activities and expression of key enzymes were analyzed in HA-treated fruit. HA treatment enhanced phenylpropanoid metabolism, as evidenced by elevated levels of phenolics and flavonoids, higher activities of phenylalanine ammonia-lyase and cinnamate-4-hydroxylase, and upregulated expression of LeCHS, LeCHI, LeF3H, and LeFLS. Levels of several phenylpropanoid metabolites were higher after HA treatment, including p-coumaric acid, caffeic acid, chlorogenic acid, isoquercitrin, quercetin, and rutin. These metabolic changes may be related to the reduced disease incidence and smaller lesion diameters observed in HA-treated fruit inoculated with Alternaria alternata (black mold) or Botrytis cinerea (gray mold). The results suggest that HA treatment induces disease resistance by activating the phenylpropanoid pathway in cherry tomato fruit.Keywords: cherry tomato; hot air treatment; induced resistance; phenylpropanoid metabolism; postharvest disease;

•Sequenced wave signals extraction and classification algorithm for duck egg crack detection.•Sequenced wave signals were caused by cracks, air cell membrane, and shell texture.•Sequenced wave signals caused by air cell membrane and shell texture were eliminated.•High accuracy was achieved to classify the cracked duck eggs and salted duck eggs.A method to detect the shell cracks in translucent images of duck eggs and salted duck eggs is presented. The method consists of a sequenced wave signal extraction algorithm to extract the sequenced wave signals from the translucent images of duck eggs. Furthermore, the characteristic parameters of the extracted sequenced wave signals are calculated and analyzed. The analysis results showed that, the sequenced wave signals extracted from egg translucent images are caused by three factors: (i) egg cracks; (ii) air cell membrane of eggs; and (iii) shell texture. The sequenced wave signals caused by egg air cell membrane and shell texture are eliminated by using characteristic parameters of the sequenced wave signals. After the elimination, a classification algorithm is used on the translucent images of eggs. In the conducted experiments, the classification algorithm achieved an accuracy of 92.5% and 93.1% for duck eggs and salted duck eggs, respectively.Download high-res image (155KB)Download full-size image

•Three optimal wavelengths were selected based on chlorophyll content via SPA.•The band ratios were used to locate the position of disease pots and classify diseased peaches.•The PLSDA model based on three band ratios show 98.75% accuracy to classify diseased peaches.•CRC images were used to visualize the spatial distribution of diseased regions on the peaches.Honey peach is a very common but highly perishable market fruit. When pathogens infect fruit, chlorophyll as one of the important components related to fruit quality, decreased significantly. Here, the feasibility of hyperspectral imaging to determine the chlorophyll content thus distinguishing diseased peaches was investigated. Three optimal wavelengths (617 nm, 675 nm, and 818 nm) were selected according to chlorophyll content via successive projections algorithm. Partial least square regression models were established to determine chlorophyll content. Three band ratios were obtained using these optimal wavelengths, which improved spatial details, but also integrates the information of chemical composition from spectral characteristics. The band ratio values were suitable to classify the diseased peaches with 98.75% accuracy and clearly show the spatial distribution of diseased parts. This study provides a new perspective for the selection of optimal wavelengths of hyperspectral imaging via chlorophyll content, thus enabling the detection of fungal diseases in peaches.

The dissipation of six pesticides (carbendazim, thiabendazole, procymidone, bifenthrin, λ-cyhalothrin, and β-cyfluthrin) in shiitakes from cultivation to postharvest drying process was investigated, and the dietary exposure risk was estimated thereafter. The field trial study indicates that the half-lives of carbendazim, thiabendazole, and procymidone were much shorter than those of bifenthrin, λ-cyhalothrin, and β-cyfluthrin. Furthermore, the effects of two drying processes on the residues and processing factors (PFs) were investigated. The results showed that hot-air drying resulted in higher residues than sunlight exposure drying. Both drying processes led to pesticide residue concentration (with PF > 1), except for thiabendazole upon sunlight exposure treatment. The estimated daily intakes (EDIs) ranged from 0.06% of the acceptable daily intake (ADI) for thiabendazole to 42.43% of the ADI for procymidone. The results show that the six pesticide residues in dried shiitakes are still within acceptable levels for human consumption on the basis of a dietary risk assessment.Keywords: dietary risk assessment; dissipation behavior; drying process; pesticide residues; processing factor; shiitakes;

The objective of this study was to investigate the effect of infrared (IR) heating and tempering treatments on storage stability of rough and brown rice. Samples of freshly harvested medium grain rice variety M206 with initial moisture content of 25.03 ± 0.21 % (d.b.) were used. They were dried using IR, hot air at 43 °C, and ambient air for comparison. For IR drying, rice were heated to temperature of 60 °C under radiation intensity of 4685 W/m2, followed by 4 h tempering and natural cooling. The dried samples were divided into two portions, which were respectively used as rough and brown rice for storage at 35 ± 1 °C with relative humidity of 65 ± 3 % for 10 months. The drying characteristics and milling quality of rice were determined. Free fatty acid, peroxide value, and iodine value were determined to detect any notable degradation of lipids in rough and brown rice during storage. High heating and drying rates of rice were achieved under IR heating. It took only 58 s to heat rough rice to temperature of 60 °C with a corresponding moisture removal of 2.17 percentage points during IR heating. The total moisture removal after natural cooling reached to 3.37 percentage points without additional energy input. IR drying did not show any adverse effects on milling quality of the dried rice. Additionally, it resulted in an effective inactivation of lipase, and consequent improvement in the long-term storage stability of rough and brown rice was achieved under accelerated storage condition. It is concluded that the improvement in rough and brown rice stability during storage can be achieved through drying rough rice using IR heating to temperature of 60 °C followed by tempering for 4 h and natural cooling. IR drying provides a potential to store brown rice instead of rough rice with extended shelf life and reduced cost.

Recently, considerable attention has been paid to the biologically active of fruit and vegetable processing wastes. In this study, antibacterial properties and major bioactive constituents of Chinese water chestnut peels (CWCP) extracts and fractions were evaluated. The data displayed that ethyl acetate fractions (EF) from CWCP showed greater antibacterial activity than n-butanol fractions, methanol extracts and water fractions against three common foodborne pathogenic bacteria (Staphylococcusaureus, Escherichia coli and Listeria monocytogenes) assessed by the inhibition zone, minimal inhibition concentration and minimal bactericidal concentration values. In accordance with disc diffusion assay, S. aureus was more susceptible to EF than the other two pathogens. Furthermore, action-mode studies indicated that EF exhibited significant bactericidal activity against S. aureus by degrading and disrupting the cell wall and cytoplasmic membrane, ultimately the leakage of cell contents led to cell death. Finally, high-performance liquid chromatography coupled with photodiode array and electrospray ionization mass spectrometry was used for characterization of bioactive constituents in EF, and ten flavonoids aglycons were identified or tentatively identified. The results suggest that the extracts and fractions from CWCP could be potentially used as a possible food supplement to improve food safety by the control or elimination of foodborne pathogenic bacteria.

Structural changes in albumin, globulin, glutelin, and prolamin from fresh and aged rice were characterized in this study. Infrared and Raman spectroscopies revealed changes in interactions between protein and starch, and the occurrence of structural changes involving secondary and tertiary structures of protein induced by rice aging. The α-helical structure was reduced, and aliphatic amino-acid side chains became more buried in albumin after rice aging. Oxidation of the sulfhydryl group in globulin was evident. The unordered coil in glutelin decreased, and a characteristic frequency of the free sulfhydryl group appeared. The antiparallel β-sheet in prolamin increased, the conformation of disulfide bonds changed, and tyrosine residues became exposed to a polar environment. The association between globulin and starch strengthened, whereas that between glutelin and starch diminished. These differences in structure and interactions with starch might be responsible for the dissimilar pasting properties between fresh and aged rice.

Single-stranded DNA (ssDNA) aptamers against four organophosphorus pesticides (phorate, profenofos, isocarbophos and omethoate) were simultaneously isolated from an immobilized random ssDNA library by systematic evolution of ligands by exponential enrichment (SELEX) technique. After 12 rounds of in vitro selection, five ssDNA aptamer candidates were selected and their binding affinities were identified by a novel method using a molecular beacon. Two of the five ssDNA sequences, SS2-55 and SS4-54, demonstrated higher affinities and specificities to the four organophosphorus pesticides. They were defined as broad-spectrum aptamers binding to four different targets and their simulated secondary structures showed highly distinct features with typical stem and loop structures. The dissociation constant of SS2-55 and SS4-54 binding to the four organophosphorus pesticides ranged from 0.8 to 2.5 μM. These aptamers offered application potential in the analysis and/or neutralization of the residues of the four organophosphorus pesticides.

An experimental system utilizing acoustic response system (ARS) and computer vision system (CVS) for eggshell crack detection was implemented. Firstly, the acoustic response signals were captured and analyzed, and six parameters (f1, f2, f3, f4: the dominant response frequency; CS: the mean value of coefficient of skewness; CE: the mean value of coefficient of excess) were analyzed. The ARS including a back-propagation artificial neural network model with a structure of 6 input nodes, 15 hidden nodes, and one output node was built to detect eggshell cracks. Secondly, the eggshell images were captured and processed by the computer vision system, and five geometrical characteristic parameters of crack and noise regions on the eggshell images were acquired. The CVS including a back-propagation artificial neural network model with a structure of 5 input nodes, 10 hidden nodes, and one output node was built to detect eggshell cracks. Finally, the quality of eggs, with or without cracks, was evaluated based on detection results from both CVS and ARS. This method allows the fusion of information obtained from CVS to ARS. The results showed that the detection accuracy of cracked eggs were 68 and 92%, respectively, by CVS and ARS. However, the accuracy equaled to 98% by the information infusion of two techniques. The result was superior to only one technique, and the method based on the information fusion of computer vision and acoustic response was applicable for detecting egg cracks. This research provides a new technology detection of cracked egg.

This study investigated the effects of heat treatment (hot air at 38 °C for 4 days) on wound healing in Gala and Red Fuji apple fruits (Malus domestica Borkh.) and the possible mechanism. Wounded apples were healed at either 20 or 38 °C for 4 days. During the treatment, ethylene, phenylalanine ammonia-lyase (PAL), peroxidase (POD), polyphenol oxidase (PPO), hydrogen peroxide (H2O2), and phenolic and lignin contents were measured. Following the treatment, healed wounds were inoculated with Penicillium expansum, Botrytis cinerea, and Colletotrichum acutatum, and then the decay development was observed. Results revealed that the influence of heating on wound healing in apple fruit was cultivar dependent. Compared with fruits healed at 20 °C, heating at 38 °C had a pejorative effect on wound healing in Gala apples. However, identical treatment enhanced wound healing in Red Fuji apples. Heating sharply reduced ethylene evolution, PAL and POD activity, and the accumulation of phenolic compounds and lignin around wounds in Gala apples. Alternatively, in Red Fuji apples, treatment at 38 °C significantly improved ethylene evolution and peroxide (H2O2) content at the first two days of treatment. In addition, both PAL and POD activities, and contents of phenolic compounds and lignin around wounds increased. Our findings suggest that this discrepancy in the effect of heat treatment on wound healing is due to different effects on ethylene evolution in cultivars of apple fruit.

This study investigated the effects of heat treatment (hot air at 38 °C) and antagonistic yeast (Pichia guilliermondii) alone or in combination against postharvest diseases (Botrytis cinerea, Alternaria alternata and Rhizopus nigricans) on cherry tomato fruit, and evaluated the elicitation of active defense responses. Results showed that heat treatment at 38 °C for 24 h in combination with P. guilliermondii at 1 × 108 CFU mL−1 was the most effective approach to reduce various infections on cherry tomato fruit’s wounds. Moreover, the combined heat and P. guilliermondii treatment stimulated a rapid increase of H2O2 and higher lignin deposition in cherry tomato fruit showing that the oxidative burst and biological synthesis of lignin might play important roles in the fruit’s active defense responses. In addition, the reduction of the fruit’s susceptibility to pathogens by the combined treatment was positively correlated with higher activities of phenylalanine ammonia-lyase (PAL) and β-1,3-glucanase in cherry tomato fruits, both of which are associated with plant defense responses.

Clostridium sporogenes is considered to be a non-toxingenic equivalent of proteolytic Clostridium botulinum, and it also causes food spoilage. The effects of temperature (16.6–33.4 °C), pH value (5.2–6.8) and concentration of sodium chloride (0.6–7.4%) on the growth parameters of C. sporogenes spores were investigated. The growth curves generated within different conditions were fitted using Baranyi function. Two growth parameters (growth rate, GR; lag-time, LT) of the growth curves under combined effects of temperature, pH and sodium chloride were modeled using a quadratic polynomial equation of response surface (RS) model. Mathematical evaluation demonstrated that the standard error of prediction (%SEP) obtained by RS model was 1.033% for GR and was 0.166% for LT for model establishing. The %SEP for model validation were 43.717% and 5.895% for GR and LT, respectively. The root-mean-squares error (RMSE) was in acceptable range which was less than 0.1 for GR and was less than 8.0 for LT. Both the bias factor (Bf) and accuracy factor (Af) approached 1.0, which were within acceptable range. Therefore, RS model provides a useful and accurate method for predicting the growth parameters of C. sporogenes spores, and could be applied to ensure food safety with respect to proteolytic C. botulinum control.

Effect of heat treatment (hot air at 38 °C for 36 h) and Pichia guilliermondii (P. guilliermondii), either alone or in combination, against anthracnose rot caused by Colletotrichum acutatum (C. acutatum), in loquat fruit was investigated. Results showed that the combined treatment significantly reduced natural decay, and disease incidence and lesion diameter in artificially inoculated fruit. Fruit given the combined treatment maintained low activities of catalase (CAT) during the early storage period, but CAT and superoxide dismutase (SOD) activities both rose later in storage. This corresponded with a high level of H2O2 in the early storage period and a lower level of H2O2 in the later period. At the same time, induced activity of phenylalanine ammonia-lyase (PAL) and β-1,3-glucanase stimulated synthesis of lignin, thus eliciting disease resistance. Moreover, the combined treatment significantly inhibited mycelial growth and spore germination of C. acutatum, reducing anthracnose rot of loquat fruit.

•Differentiated the deciduous-calyx pear and persistent-calyx pear of Kuerle fragrant pear with high accuracy.•Combined the image parameter and optimal wavelength to increase the detection accuracy.•Application multivariate analysis to improve the capability of the detection model.Deciduous-calyx pears of Korla fragrant pear (Pyrus sinkiangensis Yu) have a significant economic value in Xinjiang Uygur Autonomous Region, China. This study developed a non-destructive method based on hyperspectral imaging using a combination of existing analytical techniques to differentiate the deciduous-calyx pear (DCF) and persistent-calyx pear (PCF). The degrees of circularity of DCP and PCP were extracted according to its morphological characteristic; similarly, the reflectance spectra of DCP and PCP were obtained by hyperspectral imaging technology. Successive projections algorithm (SPA) combined with support vector machine (SVM) established a classification model. The DCF and PCF could be differentiated by SPA-SVM model with accuracy of 93.3% and 96.7% respectively. Our findings suggest that hyperspectral imaging can be applied to non-destructively differentiate pears, and meet the packaging standards.

•PLSR and SVR models were compared to predict egg freshness.•PCA combined with GLCM method was developed to detect egg’s internal bubbles.•An image segment algorithm was developed to identify eggs with scattered yolk.•The eggs internal qualities were inspected comprehensively.The study develops a nondestructive test based on hyperspectral imaging using a combination of existing analytical techniques to determine the internal quality of eggs, including freshness, bubble formation or scattered yolk. Successive projections algorithm (SPA) combined with support vector regression established a freshness detection model, which achieved a determination coefficient of 0.87, a root mean squared error of 4.01%, and the ratio of prediction to deviation of 2.80 in the validation set. In addition, eggs with internal bubbles and scattered yolk could be discriminated by support vector classification (SVC) model with identification accuracy of 90.0% and 96.3% respectively. Our findings suggest that hyperspectral imaging can be useful to non-destructively and rapidly assess egg internal quality.

The yeast Pichia guilliermondii was examined for its ability to control Rhizopus nigricans on tomato fruit during storage, and in order to highlight the reason for biocontrol, a possible mode of action is discussed. Results showed that autoclaved yeast culture and culture filtrate had no effect on controlling the postharvest disease caused by R. nigricans, although inoculation of P. guilliermondii prior to R. nigricans resulted in enhanced biocontrol efficacy. Moreover, rapid colonization of the yeast on wound sites was observed during the initial 3 days at 20 °C, and then the population stabilized for the remaining 4 days. This phenomenon indicated that at room temperature, P. guilliermondii could acclimatize itself to the environment of tomato fruit wounds and occupy the living space quickly. The results indicate that P. guilliermondii did not produce an antifungal substance, however, competition for nutrients and space on wounds appeared to play a role in the activity of the biocontrol and could be one of the mechanisms. In addition, the fruit inoculated with P. guilliermondii demonstrated changes in peroxidase (POD), polyphenoloxidase (PPO), superoxide dismutase (SOD), catalase (CAT), phenylalanine ammonia-lyase (PAL), chitinase (CHI) and β-1,3-glucanase activities, all of which were correlated with the onset of induced resistance. This result suggests that tomato fruit is capable of responding to the yeast P. guilliermondii, which could activate defensive enzymes and thereby induce host disease resistance.

•Hollowness in white radishes was detected by hyperspectral imaging.•Three illumination patterns were used and compared.•Important wavelengths were determined by the successive projections algorithm.•PLS-DA and back propagation neural networks were used for classifying hollowness.•Satisfactory classification accuracy was acquired using semi-transmittance mode.This study presented the detection of hollowness in the worldwide important vegetable crop white radish (Raphanus sativus L.) by using hyperspectral imaging covering the spectral range of 400–1000 nm. The hyperspectral images based on the three illumination patterns of reflectance, transmittance, and semi-transmittance were acquired from white radishes. The successive projections algorithm (SPA) was used to identify the optimal wavelengths from the three patterns of spectra. Two classifiers of partial least square discrimination analysis (PLS-DA) and back propagation artificial neural network (BPANN) were established based on the full wavelengths and selected wavelengths. Discrimination models were performed for the two-class, three-class, and five-class hollowness classifications using the mean spectra from the regions of interest (ROI) in the spectra images. The classification results showed that hyperspectral semi-transmittance imaging combined with the BPANN model performed the best classification accuracy for the two-class hollowness classification based on the full and selected wavelengths reaching 98% and 97% for the calibration and the prediction sets, respectively. Lower accuracies were obtained for the three-class and five–class hollowness classifications based on the combination of classifiers and illumination modes. The results demonstrated that hyperspectral semi-transmittance imaging was potentially useful as a non-invasive method to identify the hollowness in white radishes.