Watercore In Apples Research Articles

Changes in physicochemical property and its potential regulatory mechanism for the formation of water core of the Fuji apples post‐harvesting

SummaryThis study analysed the factors for influencing the occurrence of water core in apples and proposed a potential metabolism following its post‐harvesting. By comparing the ordinary pulp and the region within the water core in different post‐harvesting stages of the Fuji apples, although the occurrence of water core did not significantly change the appearance of the apples, its interior firmness decreased with increased cell permeability. Furthermore, fructose content decreased, and sorbitol content increased rapidly accompanied by a reduction of sorbitol dehydrogenase activity at the site of water core. The cell morphology also demonstrated that the cells became denser and the blue aggregates formed. It indicated that the cell walls were saturated with locally highly accumulated sorbitol, followed by visualised transparent spots. In summary, the occurrence of water core during the post‐harvesting of Fuji apples was found to be related to the increased sorbitol content and the corresponding decreased dehydrogenase activity.

Flavor and Texture Characteristics of 'Fuji' and Related Apple (Malus domestica L.) Cultivars, Focusing on the Rich Watercore.

Watercore is a so-called physiological disorder of apple (Malus domestica L.) that commonly occurs in several well-known cultivars. It is associated with a rapid softening of the flesh that causes a marked changed in flavor and texture. In Asia, apples with watercore are preferred and considered a delicacy because of their enhanced sweet flavor. The ‘Fuji’ cultivar, the first cultivar with rich watercore that is free from texture deterioration, has played a key role in the development of the market for desirable watercored apples. This review aimed to summarize and highlight recent studies related to the physiology of watercore in apples with special focus on ‘Fuji’ and related cultivars.

Non-Destructive Identification of Internal Watercore in Apples Based on Online Vis/NIR Spectroscopy

HighlightsA custom-designed online Vis/NIR spectroscopy system was used for real-time detection of watercore in apples.Watercore severity index (WSI) was applied for watercore severity assessment.Higher than 95.0% accuracy was obtained for total samples in classifying sound apples from watercore groups using kNN, BPNN, SVM, and 1D CNN at a detection speed of 3 apples s-1.Linear kernel SVM achieved the best classification accuracy of 96% for samples in the prediction set.Abstract. Watercore, an internal physiological disorder affecting apples, can be characterized by water-soaked, glassy regions near the fruit core. It is used as an indicator of full ripeness, storage suitability, and price of apples in many countries. Therefore, fast and non-destructive detection of watercore plays an important role in improving the commercial value of apples and reducing postharvest costs. In this study, an online visible/near-infrared (Vis/NIR) spectroscopy system was proposed for real-time detection of watercore in ‘Fuji’ apples (Malus pumila Mill.). A total of 318 samples harvested during harvest season in the same orchard were analyzed for both watercore severity index (WSI) and soluble solids content (SSC). According to the USDA watercore classification standard, all samples were classified into one of four classes (sound, slight, moderate, or severe) based on the affected area of watercore. Results showed that, although there was a positive correlation between spectral intensity and affected area of watercore, no significant relationship between affected area size and SSC could be obtained by Pearson test (correlation coefficient ~0.094). Generally, >95.0% accuracy was obtained for total samples at a detection speed of 3 apples s-1 in classifying sound from watercore groups using k-nearest neighbors (kNN) algorithm, back-propagation neural network (BPNN), support vector machine (SVM) classification, and one-dimensional convolutional neural network (1D-CNN). The best classification result was achieved by linear kernel SVM, with an accuracy of 96% for total samples. These classification algorithms showed preliminary feasibility for online screening of apples with watercore using Vis/NIR spectroscopy in industrial applications. Keywords: Apple watercore, Machine learning, Online detection, Vis/NIR spectroscopy, Watercore severity index.

TIME-RESOLVED REFLECTANCE SPECTROSCOPY FOR THE NON-DESTRUCTIVE DETECTION OF INNER ATTRIBUTES AND DEFECTS OF FRUIT

A review of the main results obtained by Time-resolved Reflectance Spectroscopy (TRS) and of its possible applications for the detection of inner attributes and defects in fruit is presented. Common spectroscopy techniques employ continuous wave light and measure the diffusively remitted intensity which is determined by both the absorption and the scattering properties of the sample. Light absorption is related to chemical properties, while scattering to physical structure. Quantification of absorption and scattering may be obtained by space- or time-resolved methods. TRS is a technique based on the measurement of the temporal delay and broadening experienced by a short laser pulse while traveling through a turbid medium and explores a volume of pulp at a depth of 1-2 cm. TRS has been used to detect some internal defects and disorders in the intact fruit, such as brown heart, internal browning, internal bruises, water soaked tissue, as well as internal attributes related to maturity, texture and cell wall structure. The scattering coefficient was found to be related to the translucency of tissue and was used to detect internal bruises and water soaked tissue (i.e., water core in apples and Botrytis decayed kiwifruits). The scattering coefficient was related to pectin composition and textural properties of apples such as firmness and mealiness. Absorption coefficient in the 600-700 nm region can detect brown heart in pears and internal browning in apples. The absorption coefficient at 670 nm is related to fruit maturity and it was used in nectarines to predict their softening time and to detect too immature fruit which are not able to ripen. Being non-destructive, TRS measurements can be repeated on the same fruit, following the development and the changes occurring with ripening or storage.

Cellular compartmentation and membrane permeability to sugars in relation to early or high temperature-induced watercore in apples

Early watercore was observed in apples ( Malus domestica Borkh.) from the outer canopy of ‘Orin’, an early watercore susceptible cultivar, while there was no watercore in ‘Orin’ fruit from the inner canopy and resistant ‘Fuji’. Sorbitol content was higher not only in the free space but also in the vacuole and cytoplasm in watercored ‘Orin’ than in other non-watercored fruit. Comparing watercored apples to non-watercored fruit of ‘Orin’, higher fructose and glucose in the vacuole and no significant difference in the distribution rate of sorbitol to each compartment were observed. Watercored ‘Orin’ apples showed significantly higher permeability of tonoplast to fructose, glucose, and sorbitol than those in other non-watercored apples. The permeability of plasma membrane to each sugar was much higher than that of tonoplast but no marked difference was observed among the treatments. The results suggest that metabolism of sorbitol could be active even in watercored ‘Orin’ apples and the accumulated sorbitol in the intercellular spaces might be primarily due to an active unloading from the phloem and not be brought by increased leakage from the cells.

Comparative study of water core in Red Delicious and Golden Delicious apples of Himachal Pradesh.

This paper presents the transmission technique, which has been designed and developed for the study of water core in apple cultivars Red Delicious and Golden Delicious of Himachal Pradesh, India. The principle of this method is to measure the optical density of the sample at 2 selected wavelengths and computation of the optical density difference. It has been observed that Golden Delicious is more prone to water core than Red Delicious. The technique is simple and can be conveniently implemented to develop an on-line instrument to monitor water core in apples.

Varietal Differences in Susceptibility to Early or High Temperature-induced Watercore in Apples

To determine the susceptibility to early or high temperature-induced watercore, seasonal changes in the incidence and intensity of watercore, ethylene evolution, and sorbitol content in 4 apple (Malus pumila Mill. var. domestica Schneid.) cultivars grown at Matsuyama were investigated. Mean air temperature was above 25°C from early July to mid-September. ‘Himekami’ and ‘Shinsekai’ apples started to develop watercore from mid- and early August, respectively, before the onset of ethylene production. The incidence and intensity of watercore in ‘Orin’ apples increased from mid-July to early September, followed by a decrease through late October, whereas no watercore was observed until early November in ‘Fuji’. In conclusion, ‘Himekami’ and ‘Shinsekai’ are regarded as moderately, and ‘Orin’ as highly susceptible to early or high temperature-induced watercore, whereas ‘Fuji’ is considered as being resistant. Significant correlations between sorbitol and early or high temperature-induced watercore were observed.

Application of Time-of-flight Near-infrared Spectroscopy for Detecting Water Core in Apples

Time-of-flight near-infrared spectroscopy (TOF-NIRS) was used to investigate optical characteristics of water-cored tissue in `Fuji' apples [Malus sylvestris (L.) Mill. var. domestica (Borkh. Mansf.)]. The combined effects on the time resolved profiles of water core, laser beam wavelength, and detection position of transmitted light were investigated in detail. Attenuance of peak maxima (At), time delay of peak maxima (Δt), and variation of full width at half maximum (Δw) decreased gradually as water core increased. Water-cored tissue transmitted much more energy because of the filling of intercellular spaces with liquid, so that the light path time through a sample decreased. These parameters were also strongly dependent on detection position and wavelength of the laser beam. The substantial optical path length calculated from Δt at λ = 800 nm was 10 to 17 times, while that for λ = 900 nm varied from six to 11 times the distance of the diameter of the fruit. Results indicated the optimum optical parameter for detection of water core was Δt.

Development of Early Watercore in 'Orin' Apples Grown in Warmer Regions and its Physiology.

The occurrence of watercore in 'Orin' apples (Malus pumila Mill. var. domestica Schneid.) was prevalent from late August to late September ; there was a significant correlation between watercore rating and maximum fruit temperature during late August. The watercore occurred in immature apples long before the increase of ethylene and 1-aminocyclopropane-1-carboxylic acid (ACC), indicating that the watercore observed in this study was early watercore. Membrane permeability increased from mid-August to mid-September and showed a significant correlation with watercore. The degree of watercore during late August was significantly correlated with flesh firmness, soluble solids content (SSC), total sugars, fructose, glucose in the inner flesh, and sorbitol but not with titratable acidity, starch, and sucrose. The seasonal changes in sorbitol content paralleled the incidence of watercore ; the coefficients of correlation between them were 0.881 and 0.827 for the inner and outer flesh tissue, respectively. These results indicate that the changes in physiological factors such as membrane permeability and sorbitol content in the fruit during summer play an important role in inducing early watercore in apples. We propose that the physiological mechanism of early watercore development in immature apples is similar to that of high temperature-induced watercore during maturation but differs from that of low temperature-promoted late watercore.

Preharvest factors affecting physiological disorders of fruit

Abstract Development of disorders during postharvest ripening and storage of fruit depends on a range of preharvest factors. The most obvious of these is maturity of fruit at harvest. However, a number of other factors may be just as important in ripening-related disorders and in determining how fruit respond to low temperatures or other imposed postharvest conditions. Fruiting position on the tree and fruit temperature history are two of the most important of these factors. In apples, position strongly influences fruit mineral contents, and consequently incidence of postharvest disorders such as bitter pit. This positional effect may reflect pollination and cropping effects, or more direct differences in flow of minerals and water into developing fruit. In both apples and avocado fruit, we have shown that high temperatures experienced by fruit on the tree can influence the response of those fruit to low and high postharvest temperatures. Specific disorders such as watercore in apples and chilling injury in avocado can also be related to fruit exposure to sunlight and high temperatures; disorders such as scald in apples may be related to frequency of low temperature exposure over the season. Identification of preharvest factors raises the possibility of producing fruit with less predisposition to postharvest disorders.

HYDRAULIC SORTING OF WATERCORE APPLES

The presence of watercore in apples occurs significantly about one out of every three years in Washington State. It is desirable to separate fruit that are affected from those that are not, since moderately to severely affected fruit cannot be successfully stored for an extended period. The lack of a practical method to separate fruit with watercore from those without leads to the untimely marketing of fruit that otherwise could have been placed into long term storage. This paper presents the results of our research on development of a high volume separation device, compatible with existing apple packing lines. The prototype device creates a region of controlled lower density fluid through which fruit passes and in which the fruit is separated. The prototype correctly separated 100% of fruit that were moderately or severely affected (specific gravities equal to or greater than 0.90) from those that were less affected, irrespective of fruit size. Fruit that were less than moderately affected (specific gravities between 0.90 and 0.88) were separated from those with slight or no watercore with 80-90% accuracy, depending on fruit size. The blind test used 245 'Red Delicious' apples that were sorted under 5 conditions with 3 replications each (n = 3,675).

Effects of Storage Duration on Detecting Watercore in Apples Using Machine Vision

Measuring the amount of light transmitted through an apple has had limited success for detecting watercore in apples when the measurements were made soon after harvest. However, errors associated with this technique when applied to apples coming out of cold storage has yet to be determined. Using a machine vision system to view the stem-end of the apple while illuminating the calyx, the intensity of light transmitted through individual apples was measured biweekly for 14 weeks in 1990. The mean gray-level of the pixels within a square window centered about the stem was representative of the intensity of the light transmitted through the fruit. The intensity of light transmitted through the fruit decreased with time for all classes of watercored fruit. Based upon the initial levels defined for each class, this decrease in light transmission resulted in misclassifying watercored fruit as watercore-free at the end of the time study. Of 72 fruit initially classified as severely watercored, 18% of the fruit were misclassified as watercore-free, because three apples still had evidence of watercore, while eight fruit exhibited internal browning, due to watercore.

リンゴのミツ症状

リンゴのミツ症状

Application of Computer Vision for Detecting Watercore in Apples

ABSTRACT Two methods for detecting and classifying watercore in 'Red Delicious' apples using computer vision techniques were examined. The first method used was to average radii perpendicular and parallel to the stem-calyx axis for each apple and use these radii to compute an approximate apple volume which, in conjunction with measured weight of fruit, was used to calculate weight density. A correlation of 0.98 was found between the computed volume and measured volume. Weight density correctly separated 86.7% of a 60-apple test sample with 5.0% misclassified as having watercore and 8.3% misclassified as watercore free. The second method used was to measure light transmission through apples, viewed from the stem-end, as an indicator of watercore. The mean grey level of a 130 pixel X 100 pixel window located around the fruit center indicated the presence of watercore, but was not a good feature for accurately measuring the degree of watercore. All of the 60-apple test samples were correctly classified for the presence or absence of watercore. Application of computer vision techniques to measure transmissibility of visible radiation through apples by finding the mean grey level is a feasible method for detecting watercore presence, but cannot determine how severe the watercore damage is. This noncontact method for separating and marketing of watercore fruit could reduce the storage losses due to core browning and decay..

Sorbitol Metabolism, the Climacteric, and Watercore in Apples

Abstract Extraction and assay of sorbitol dehydrogenase (SDH) throughout fruit maturation of 3 apple (Malus domestica Borkh.) cultivars, watercore-resistant ‘Golden Delicious,’ occasionally susceptible ‘McIntosh’, and normally susceptible ‘Starkrimson,’ showed no relationship between susceptibility to watercore and extractable enzyme activity. There was, however, a relationship between increased SDH activity and onset of the climacteric as measured by ethylene and CO2 evolution, suggesting that SDH, like certain other enzymes, increases during maturation.