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Mealy peaches are dry and flavorless, which reduces their consumer acceptance. A deeper understanding of the mechanism underlying mealiness is crucial to enhancing peach fruit quality. In this study, comparative profiling was conducted on CP13, CP14, CM, and RM peaches. Sensory evaluation indicated that CP13 and CM are non-mealy clingstone and freestone peaches, respectively, and CP14 and RM are mealy freestone peaches. Both CP13 and CP14, identified as stony hard (SH) peaches, exhibited minimal ethylene release, whereas CM and RM, identified as melting flesh (MF) peaches, released high amounts of ethylene during the ripening process. Scanning electron microscopy (SEM) microstructure observation indicated that cells in the flesh tissue of mealy peaches, CP14 (SH) and RM (MF), were intact and separated, with large intercellular spaces and irregular arrangements. The main factor that promotes mealiness is differences in pectin metabolism, which impact cell wall composition. The fluctuations in polygalacturonase (PG) and pectin methylesterase (PME) activity between mealy and non-mealy peaches were the main factor contributing to mealiness. However, the changes in cell wall metabolism that caused these fluctuations did not have a clear direction. Using transcriptome analysis and weighted gene co-expression network analysis (WGCNA), we were able to identify forty differentially expressed genes (DEGs) that are associated with mealy patterns. Among these DEGs, genes encoding PG were significantly upregulated in mealy peaches (CP14 and RM) compared to non-mealy peaches (CP13 and CM). PpPG1 was the main effector gene for mealiness, while PpPG2, PpEGase2, PpEXP1, PpEXP3, PpAGP2, PpIAA4, and PpABA2 were identified as candidate genes regulating peach mealiness. These findings provide a solid experimental basis for understanding the textual distinctions between mealy and non-mealy peaches. [ABSTRACT FROM AUTHOR]

Lowering the storage temperature is an effective method to extend the postharvest and shelf life of fruits. Nevertheless, this technique often leads to physiological disorders, commonly known as chilling injuries. Apples and pears are susceptible to chilling injuries, among which superficial scald is the most economically relevant. Superficial scald is due to necrotic lesions of the first layers of hypodermis manifested through skin browning. In peaches and nectarines, chilling injuries are characterized by internal symptoms, such as mealiness. Fruits with these aesthetic or compositional/structural defects are not suitable for fresh consumption. Genetic variation is a key factor in determining fruit susceptibility to chilling injuries; however, physiological, or technical aspects such as harvest maturity and storage conditions also play a role. Multi-omics approaches have been used to provide an integrated explanation of chilling injury development. Metabolomics in pome fruits specifically targets the identification of ethylene, phenols, lipids, and oxidation products. Genomics and transcriptomics have revealed interesting connections with metabolomic datasets, pinpointing specific genes linked to cold stress, wax synthesis, farnesene metabolism, and the metabolic pathways of ascorbate and glutathione. When applied to Prunus species, these cutting-edge approaches have uncovered that the development of mealiness symptoms is linked to ethylene signaling, cell wall synthesis, lipid metabolism, cold stress genes, and increased DNA methylation levels. Emphasizing the findings from multi-omics studies, this review reports how the integration of omics datasets can provide new insights into understanding of chilling injury development. This new information is essential for successfully creating more resilient fruit varieties and developing novel postharvest strategies. [ABSTRACT FROM AUTHOR]

Mealy peaches are dry and flavorless, which reduces their consumer acceptance. A deeper understanding of the mechanism underlying mealiness is crucial to enhancing peach fruit quality. In this study, comparative profiling was conducted on CP13, CP14, CM, and RM peaches. Sensory evaluation indicated that CP13 and CM are non-mealy clingstone and freestone peaches, respectively, and CP14 and RM are mealy freestone peaches. Both CP13 and CP14, identified as stony hard (SH) peaches, exhibited minimal ethylene release, whereas CM and RM, identified as melting flesh (MF) peaches, released high amounts of ethylene during the ripening process. Scanning electron microscopy (SEM) microstructure observation indicated that cells in the flesh tissue of mealy peaches, CP14 (SH) and RM (MF), were intact and separated, with large intercellular spaces and irregular arrangements. The main factor that promotes mealiness is differences in pectin metabolism, which impact cell wall composition. The fluctuations in polygalacturonase (PG) and pectin methylesterase (PME) activity between mealy and non-mealy peaches were the main factor contributing to mealiness. However, the changes in cell wall metabolism that caused these fluctuations did not have a clear direction. Using transcriptome analysis and weighted gene co-expression network analysis (WGCNA), we were able to identify forty differentially expressed genes (DEGs) that are associated with mealy patterns. Among these DEGs, genes encoding PG were significantly upregulated in mealy peaches (CP14 and RM) compared to non-mealy peaches (CP13 and CM). PpPG1 was the main effector gene for mealiness, while PpPG2, PpEGase2, PpEXP1, PpEXP3, PpAGP2, PpIAA4, and PpABA2 were identified as candidate genes regulating peach mealiness. These findings provide a solid experimental basis for understanding the textual distinctions between mealy and non-mealy peaches.

Lowering the storage temperature is an effective method to extend the postharvest and shelf life of fruits. Nevertheless, this technique often leads to physiological disorders, commonly known as chilling injuries. Apples and pears are susceptible to chilling injuries, among which superficial scald is the most economically relevant. Superficial scald is due to necrotic lesions of the first layers of hypodermis manifested through skin browning. In peaches and nectarines, chilling injuries are characterized by internal symptoms, such as mealiness. Fruits with these aesthetic or compositional/structural defects are not suitable for fresh consumption. Genetic variation is a key factor in determining fruit susceptibility to chilling injuries; however, physiological, or technical aspects such as harvest maturity and storage conditions also play a role. Multi-omics approaches have been used to provide an integrated explanation of chilling injury development. Metabolomics in pome fruits specifically targets the identification of ethylene, phenols, lipids, and oxidation products. Genomics and transcriptomics have revealed interesting connections with metabolomic datasets, pinpointing specific genes linked to cold stress, wax synthesis, farnesene metabolism, and the metabolic pathways of ascorbate and glutathione. When applied to Prunus species, these cutting-edge approaches have uncovered that the development of mealiness symptoms is linked to ethylene signaling, cell wall synthesis, lipid metabolism, cold stress genes, and increased DNA methylation levels. Emphasizing the findings from multi-omics studies, this review reports how the integration of omics datasets can provide new insights into understanding of chilling injury development. This new information is essential for successfully creating more resilient fruit varieties and developing novel postharvest strategies.

In apricots and other stonefruit, chilling injury (CI) symptoms like mealiness, rubberiness, and gel formation are associated with cell wall properties. Apricots were stored at 0 °C for 5 weeks and ripened at 20 °C to induce CI and compared with fruit ripened at 20 °C from harvest at similar firmness. In those apricots without CI, degradation of middle-lamella pectin during softening weakened cell-cell adhesion and intercellular junctions. Pectin was still present in middle lamella regions but pectin that filled the intercellular spaces at harvest had disappeared. Fruit with combinations of CI symptoms showed different pectin solubilities, molecular weight distribution, and differences in pectin staining compared with fruit that were severely chilling-injured, exhibiting all symptoms. The perception of mealiness correlated with the presence of pectin in the cell lumen, and rubberiness with the presence of pectin in tricellular corners. We concluded that in chilling-injured apricots, the normal softening process is not being resumed after fruit have been taken out of cold storage. Cell wall degradation is disrupted, affecting the normal weakening of cell walls during softening. Hence, cell walls were less likely to break open during chewing, and when cells did break, any juice released might be bound by pectin present in the cell walls and cell lumen, leaving a sensation of rubberiness and mealiness. [ABSTRACT FROM AUTHOR]

The sweetpotato breeding process involves assessing different phenotypic traits, such as the sensory attributes, to decide which varieties to progress to the next stage during the breeding cycle. Sensory attributes like appearance, taste, colour and mealiness are important for consumer acceptability and adoption of new varieties. Therefore, measuring these sensory attributes is critical to inform the selection of varieties during breeding. Current methods using a trained human panel enable screening of different sweetpotato sensory attributes. Despite this, such methods are costly and time-consuming, leading to low throughput, which remains the biggest challenge for breeders.In this paper, we describe an approach to apply machine learning techniques with image-based analysis to predict flesh-colour and mealiness sweetpotato sensory attributes. The developed models can be used as high-throughput methods to augment existing approaches for the evaluation of flesh-colour and mealiness for different sweetpotato varieties. The work involved capturing images of boiled sweetpotato cross-sections using the DigiEye imaging system, data pre-processing for background elimination and feature extraction to develop machine learning models to predict the flesh-colour and mealiness sensory attributes of different sweetpotato varieties. For flesh-colour the trained Linear Regression and Random Forest Regression models attained R2 values of 0.92 and 0.87, respectively, against the ground truth values given by a human sensory panel. In contrast, the Random Forest Regressor and Gradient Boosting model attained R2 values of 0.85 and 0.80, respectively, for the prediction of mealiness. The performance of the models matched the desirable R2 threshold of 0.80 for acceptable comparability to the human sensory panel showing that this approach can be used for the prediction of these attributes with high accuracy. The machine learning models were deployed and tested by the sweetpotato breeding team at the International Potato Center in Uganda. This solution can automate and increase throughput for analysing flesh-colour and mealiness sweetpotato sensory attributes. Using machine learning tools for analysis can inform and quicken the selection of promising varieties that can be progressed for participatory evaluation during breeding cycles and potentially lead to increased chances of adoption of the varieties by consumers.

In apricots and other stonefruit, chilling injury (CI) symptoms like mealiness, rubberiness, and gel formation are associated with cell wall properties. Apricots were stored at 0 °C for 5 weeks and ripened at 20 °C to induce CI and compared with fruit ripened at 20 °C from harvest at similar firmness. In those apricots without CI, degradation of middle-lamella pectin during softening weakened cell-cell adhesion and intercellular junctions. Pectin was still present in middle lamella regions but pectin that filled the intercellular spaces at harvest had disappeared. Fruit with combinations of CI symptoms showed different pectin solubilities, molecular weight distribution, and differences in pectin staining compared with fruit that were severely chilling-injured, exhibiting all symptoms. The perception of mealiness correlated with the presence of pectin in the cell lumen, and rubberiness with the presence of pectin in tricellular corners. We concluded that in chilling-injured apricots, the normal softening process is not being resumed after fruit have been taken out of cold storage. Cell wall degradation is disrupted, affecting the normal weakening of cell walls during softening. Hence, cell walls were less likely to break open during chewing, and when cells did break, any juice released might be bound by pectin present in the cell walls and cell lumen, leaving a sensation of rubberiness and mealiness.

Peaches and nectarines are temperate climate stone fruits, which should be stored at 0°C to prevent the ripening of these climacteric fruits. However, if stored for too long or if stored at a higher temperature (4 or 5 °C), they develop chilling injury. Chilling injury damage includes (1) dry, mealy, wooly (lack of juice) fruits, (2) hard-textured fruits with no juice (leatheriness), (3) flesh browning, and (4) flesh bleeding or internal reddening. There are genetic components to these disorders in that early season fruits are generally more resistant than late season fruits, and white-fleshed fruits are more susceptible to internal browning than yellow-fleshed fruits. A recent review covered the recent research in genomic and transcriptomic studies, and this review examines findings from proteomic and metabolomics studies. Proteomic studies found that the ethylene synthesis proteins are decreased in cold compromised fruits, and this affects the processes initiated by ethylene including cell wall and volatile changes. Enzymes in metabolic pathways were both higher and lower in abundance in CI fruits, an indication of an imbalance in energy production. Stress proteins increased in both fruits with or without CI, but were higher in damaged fruits. Metabolomics showed the role of levels of sugars, sucrose, raffinose, galactinol, and glucose-6-phosphate in protection against chilling injury, along with other membrane stabilizers such as polyamines. Amino acid changes were inconsistent among the studies. Lipid species changes during storage could be correlated with sensitivity or resistance to CI, but more studies are needed. [ABSTRACT FROM AUTHOR]

Peaches and nectarines are temperate climate stone fruits, which should be stored at 0°C to prevent the ripening of these climacteric fruits. However, if stored for too long or if stored at a higher temperature (4 or 5°C), they develop chilling injury. Chilling injury damage includes (1) dry, mealy, wooly (lack of juice) fruits, (2) hard-textured fruits with no juice (leatheriness), (3) flesh browning, and (4) flesh bleeding or internal reddening. There are genetic components to these disorders in that early season fruits are generally more resistant than late season fruits, and white-fleshed fruits are more susceptible to internal browning than yellow-fleshed fruits. A recent review covered the recent research in genomic and transcriptomic studies, and this review examines findings from proteomic and metabolomics studies. Proteomic studies found that the ethylene synthesis proteins are decreased in cold compromised fruits, and this affects the processes initiated by ethylene including cell wall and volatile changes. Enzymes in metabolic pathways were both higher and lower in abundance in CI fruits, an indication of an imbalance in energy production. Stress proteins increased in both fruits with or without CI, but were higher in damaged fruits. Metabolomics showed the role of levels of sugars, sucrose, raffinose, galactinol, and glucose-6-phosphate in protection against chilling injury, along with other membrane stabilizers such as polyamines. Amino acid changes were inconsistent among the studies. Lipid species changes during storage could be correlated with sensitivity or resistance to CI, but more studies are needed.

Apple flesh tends to turn mealy and textural deterioration commonly occurs during storage. The comparative investigation of three sub-fractions separated from sodium carbonate-soluble pectin (SSP) of 'Hongjiangjun' apples between crisp and mealy stages was performed to unveil the textural alterations related to mealiness. In situ immunofluorescence labelling showed that galactans declined in parenchyma cell walls during the fruit mealiness. FTIR analysis, monosaccharide compositions and structural polymers configurated that loss of rhammogalacturonan-I (RG-I) from SSP sub-fragments (S C0.0-P and S-M0.0-P) might be closely involved in the mealiness. The NMR spectroscopy revealed that loss of the substituted galactans from α -Rha p residues repeat unit in S C0.0-P constituting RG-I in crisp stage that subsequently converted to S-M0.0-P in mealy stage might be closely associated with the modifications of pectin in cell walls during mealiness. These findings provided novel evidence for understanding the underlying modifications of SSP polymers during the mealiness of 'Hongjiangjun' apples. [Display omitted] • The immunofluorescent signal of galactan in mealy apple cells was sharply weakened. • Apple mealiness altered the sub-fragments of sodium carbonate-soluble pectin (SSP). • The mealiness of apple involved the loss of galactan on the RG-I chain in SSP. • The fine structure of product of RG-I degradation were putatively established. [ABSTRACT FROM AUTHOR]

BACKGROUND: Salicylic acid (SA) and jasmonic acid (JA) can both enhance resistance of chilling injury (CI) in cold‐storage peach fruit, but the regulatory mechanisms involved and whether there is a coordinated regulation between them is unclear. In this study, postharvest peach fruit were treated with an aqueous SA solution for 15 min or an aqueous JA solution for 30 s before storage at 4 °C for 35 days. RESULTS: SA and JA treatments both delayed and reduced development of internal browning (a symptom of CI) and induced the accumulation of hydrogen peroxide and sucrose. The SA and JA also reduced catalase and peroxidase activities, which are involved in hydrogen peroxide generation. The SA and JA treatments significantly regulated the transcript abundance of genes related to sucrose biosynthesis and degradation consistent with the observed increase in sucrose content. CONCLUSION: These results intimate that JA and SA may be involved in coordinating the alleviation of CI via increased accumulation of sucrose. © 2021 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The peach is the third most important temperate fruit crop considering fruit production and harvested area in the world. Exporting peaches represents a challenge due to the long-distance nature of export markets. This requires fruit to be placed in cold storage for a long time, which can induce a physiological disorder known as chilling injury (CI). The main symptom of CI is mealiness, which is perceived as non-juicy fruit by consumers. The purpose of this work was to identify and compare the metabolite and lipid profiles between two siblings from contrasting populations for juice content, at harvest and after 30 days at 0 °C. A total of 119 metabolites and 189 lipids were identified, which showed significant differences in abundance, mainly in amino acids, sugars and lipids. Metabolites displaying significant changes from the E1 to E3 stages corresponded to lipids such as phosphatidylglycerol (PG), monogalactosyldiacylglycerol (MGDG) and lysophosphatidylcholines (LPC), and sugars such as fructose 1 and 1-fructose-6 phosphate. These metabolites might be used as early stage biomarkers associated with mealiness at harvest and after cold storage.

Aquaphotomics is a scientific discipline which investigates the water-light interactions in biological systems by using NIR spectroscopy and multivariate analysis to relate water absorption patterns to bio-functionalities. This work aimed at evaluating the feasibility of Aquaphotomics to study apple fruit sensory texture. ‘Braeburn’, ‘Gala’ and ‘Kanzi®’ apples were analyzed by a MicroNIR spectrometer and for mechanical, structural and texture sensory characteristics. Cluster analysis on sensory texture attributes showed four different profiles for each cultivar having different water spectral patterns (WASP). On average, the WASP of mealy apples showed the highest absorbance values at 1364, 1372 and 1382 nm and the lowest in the 1438-1492 nm range suggesting a preponderance of water structures with weak-hydrogen bonds; the opposite was found in crispy and juicy apples indicating the presence of more organized water structures with medium-strong hydrogen bonds. This WASP difference could be due to a different softening rate: apples clustered as firm/crispy/juicy had the highest firmness and the lowest intercellular spaces, while mealy apples had low firmness and high intercellular spaces indicating a more advanced softening. The chemical changes due to the pectin hydrolyzation could affect the water structures. The Aquaphotomics approach could be a useful tool for studying the sensory texture of fruits as water structures actually change in apples with different textural characteristics whatever the cultivars.

Grain hardness is one of the most important quality characteristics of wheat (Triticum aestivum L.). It is a significant property of wheat grains and relates to milling quality and end product quality. Grain hardness is caused by the presence of puroindoline genes (Pina and Pinb). A collection of 25 genotypes of wheat with unusual grain colour (blue aleurone, purple and white pericarp, yellow endosperm) was studied by polymerase chain reaction (PCR) for the diversity within Pina and Pinb (alleles: Pina-D1a, Pina-D1b, Pinb-D1a, Pinb- -D1b, Pinb-D1c and Pinb-D1d). The endosperm structure was determined by a non-destructive method using light transfl ectance meter and grain hardness by a texture analyser. Genotype Novosibirskaya 67 and isogenic ANK lines revealed hitherto unknown alleles at the locus for the annealing of primers of Pinb-D1. Allele Pinb-D1c was found to be absent from each genotype. The mealy endosperm ranged from 0 to 100 % and grain hardness from 15.10 to 26.87 N per sample.

Background: The morphological identification is an effective and simple quality evaluation method in Chinese drugs, and the traits of mealiness and color were widely used in the commercial market of Chinese drugs. Objective: The objective of this study was to explore the correlation between mealiness of herbal drugs and its quality; licorice was selected as an example. Materials and Methods: The mealiness of licorice was graded by its weight; meanwhile, the content of glycyrrhizic acid and liquiritin was determined by high-performance liquid chromatography-diode-array detection method; the content of polysaccharides, soluble sugars, pectin, total starch, amylose, and amylopectin was measured by colorimetric method; and the number and diameter of starch granule were observed by microscope. Results: The results showed that the mealiness of licorice which collected from wild and cultivated plants is positively correlated with the content of glycyrrhizic acid, liquiritin, the ratio of amylose to total starch, and the number of starch granules whose diameter was over 5 μm. However, the mealiness is negatively correlated with the total starch. Further, the formation mechanism of starch granule was discussed. Conclusion: It is for the first time to report the positive correlation between the mealiness and the starch granule size, the ratio of amylose to total starch, which can provide rationality for the quality evaluation using the character of mealiness in herbal medicine. [ABSTRACT FROM AUTHOR]

The sweetpotato breeding process involves assessing different phenotypic traits, such as the sensory attributes, to decide which varieties to progress to the next stage during the breeding cycle. Sensory attributes like appearance, taste, colour and mealiness are important for consumer acceptability and adoption of new varieties. Therefore, measuring these sensory attributes is critical to inform the selection of varieties during breeding. Current methods using a trained human panel enable screening of different sweetpotato sensory attributes. Despite this, such methods are costly and time-consuming, leading to low throughput, which remains the biggest challenge for breeders. In this paper, we describe an approach to apply machine learning techniques with image-based analysis to predict flesh-colour and mealiness sweetpotato sensory attributes. The developed models can be used as high-throughput methods to augment existing approaches for the evaluation of flesh-colour and mealiness for different sweetpotato varieties. The work involved capturing images of boiled sweetpotato cross-sections using the DigiEye imaging system, data pre-processing for background elimination and feature extraction to develop machine learning models to predict the flesh-colour and mealiness sensory attributes of different sweetpotato varieties. For flesh-colour the trained Linear Regression and Random Forest Regression models attained R 2 values of 0.92 and 0.87, respectively, against the ground truth values given by a human sensory panel. In contrast, the Random Forest Regressor and Gradient Boosting model attained R 2 values of 0.85 and 0.80, respectively, for the prediction of mealiness. The performance of the models matched the desirable R 2 threshold of 0.80 for acceptable comparability to the human sensory panel showing that this approach can be used for the prediction of these attributes with high accuracy. The machine learning models were deployed and tested by the sweetpotato breeding team at the International Potato Center in Uganda. This solution can automate and increase throughput for analysing flesh-colour and mealiness sweetpotato sensory attributes. Using machine learning tools for analysis can inform and quicken the selection of promising varieties that can be progressed for participatory evaluation during breeding cycles and potentially lead to increased chances of adoption of the varieties by consumers., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2023 The Author(s).)

O objetivo deste trabalho foi avaliar a qualidade física e química e a incidência de distúrbios fisiológicos em pêssegos 'Chiripá' submetidos a diferentes formas de pré-resfriamento. Os tratamentos avaliados foram: [1] resfriamento convencional em câmara frigorífica (-0,5°C e UR de 95%); [2] resfriamento sob ar forçado (-1,5°C) até a temperatura da polpa atingir 0°C; [3] resfriamento em água a 1°C (RA) até 15°C; [4] RA até 10°C; [5] RA até 5°C; [6] RA até 1°C. Os frutos foram analisados após 35 dias a -0,5°C, mais dois e quatro dias a 20°C. Verificou-se menor síntese de etileno nos frutos submetidos ao resfriamento lento e ao resfriamento com ar forçado, durante o período a 20°C. Nesses frutos, a quantidade de suco livre foi significativamente menor após quatro dias a 20°C, demonstrando uma aparente relação entre a reduzida síntese de etileno e a baixa suculência, o que é uma manifestação de lanosidade. Os frutos resfriados de forma lenta apresentaram firmeza da polpa mais elevada. Todas as formas de resfriamento com a água na temperatura de 1°C resultaram em maior porcentagem de frutos com manchas na epiderme, possivelmente em razão da baixa temperatura da água do pré-resfriador, indicando que o resfriamento em água não é recomendado para pêssegos 'Chiripá'.The aim of this research was to evaluate the physic and chemical quality and the incidence of physiological disorders in Chiripá peaches submitted to different precooling forms. The treatments evaluated, were: [1] slow cooling in the storage chamber (-0.5°C e UR de 95%); [2] forced-air cooling (-1.5°C) until the pulp reached 0°C; [3] hydrocooling until the pulp reached 15°C; [4] hydrocooling until 10°C; [5] hydrocooling until 5°C; [6] hydrocooling until 1°C. The fruits were evaluated after 35 days at -0.5°C and more two and four days at 20°C. Lower ethylene synthesis during shelf-life at 20°C was verified in fruits submitted to both slow cooling and forced-air precooling. In those fruits, the succulence was significantly lower in the 4th day at 20°C, demonstrating an apparent relationship between the reduced ethylene synthesis and the largest wooliness incidence. Slow cooled fruits showed highest flesh firmness. All hydrocooling forms resulted in larger percentage of fruits with stains in the epidermis, possibly due to the low temperature of the precooler water. Therefore the precooling in water is not recommended for Chiripá peaches.

The study was carried out to evaluate the effects of nitric oxide (NO) treatment at different doses and times during controlled atmosphere (CA) storage on quality of 'Baigent' apples. The evaluated treatments were: control; 10 µL L−1 of NO applied only at the beginning of CA storage; 1, 2 or 5 µL L−1 of NO applied every 30 d of CA storage; and 5 µL L−1 of NO applied at the beginning and at the end of CA storage. Fruit were stored for 7.5 months in 1.2 kPa O₂ + 2.0 kPa CO₂, 1.5 ± 0.2 °C, and relative humidity of 94 ± 2%. NO treatments, except 10 µL L−1 NO applied only at the beginning of CA storage, reduced ethylene production. At removal from CA storage, 5 µL L−1 NO, applied every 30 d of CA storage or at the beginning and at the end of CA storage, reduced respiratory rates. Control fruit and fruit treated with 2 µL L−1 NO every 30 d of CA storage had higher soluble solids content, and control fruit and fruit treated with NO at 1 or 2 µL L−1 every 30 d of CA storage had higher titratable acidity. NO treatments, regardless of the dose and application time during CA storage, delayed skin yellowing and reduced hydrogen peroxide content and the incidence of pulp mealiness. The application of 5 µL L−1 of NO at the beginning and at the end of CA storage maintained a higher total phenolic compound content and reduced the incidence of flesh browning. Treatment with 5 µL L−1 NO at the beginning and at the end of CA storage provided better quality maintenance of 'Baigent' apples. • Treatment of 'Baigent' apples with NO in CA reduces ethylene production. • Baigent' apples treated with NO had lower incidences of mealiness and rot. • 5 µL L−1 NO at the beginning and end of CA storage reduces pulp browning. • 5 µL L−1 NO at the beginning and end of CA storage maintained of fruit quality. • The treatments with NO delayed skin yellowing and reduced hydrogen peroxide content. [ABSTRACT FROM AUTHOR]

Cold storage (CS) can induce a physiological disorder known as chilling injury (CI) in nectarine fruits. The main symptom is mealiness that is perceived as non-juicy fruit by consumers. Postharvest treatments such as controlled atmosphere (CA; a high CO2 concentration and low O2) have been used under cold conditions to avoid this disorder. With the objective of exploring the mechanisms involved in the CA effect on mealiness prevention, we analyzed transcriptomic changes under six conditions of ‘Red Pearl’ nectarines by RNA-Seq. Our analysis included just harvested nectarines, juicy non-stored fruits, fruits affected for CI after CS and fruits stored in a combination of CA plus CS without CI phenotype. Nectarines stored in cold conditions combined with CA treatment resulted in less mealiness; we obtained 21.6% of juice content compared with just CS fruits (7.7%; mealy flesh). RNA-Seq data analyses were carried out to study the gene expression for different conditions assayed. During ripening, we detected that nectarines exposed to CA treatment expressed a similar number of genes compared with fruits that were not exposed to cold conditions. Firm fruits have more differentially expressed genes than soft fruits, which suggest that most important changes occur during CS. On the other hand, gene ontology analysis revealed enrichment mainly in metabolic and cellular processes. Differentially expressed genes analysis showed that low O2 concentrations combined with cold conditions slows the metabolic processes more than just the cold storage, resulting mainly in the suppression of primary metabolism and cold stress response. This is a significant step toward unraveling the molecular mechanism that explains the effectiveness of CA as a tool to prevent CI development on fruits.

‘Fuji’ is one of the most popular and highly-produced apple cultivars worldwide, and has been frequently used in breeding programs. The development of genotypic markers for the preferable phenotypes of ‘Fuji’ is required. Here, we aimed to define the haplotypes of ‘Fuji’ and find associations between haplotypes and phenotypes of five traits (harvest day, fruit weight, acidity, degree of watercore, and flesh mealiness) by using 115 accessions related to ‘Fuji’. Through the re-sequencing of ‘Fuji’ genome, total of 2,820,759 variants, including single nucleotide polymorphisms (SNPs) and insertions or deletions (indels) were detected between ‘Fuji’ and ‘Golden Delicious’ reference genome. We selected mapping-validated 1,014 SNPs, most of which were heterozygous in ‘Fuji’ and capable of distinguishing alleles inherited from the parents of ‘Fuji’ (i.e., ‘Ralls Janet’ and ‘Delicious’). We used these SNPs to define the haplotypes of ‘Fuji’ and trace their inheritance in relatives, which were shown to have an average of 27% of ‘Fuji’ genome. Analysis of variance (ANOVA) based on ‘Fuji’ haplotypes identified one quantitative trait loci (QTL) each for harvest time, acidity, degree of watercore, and mealiness. A haplotype from ‘Delicious’ chr14 was considered to dominantly cause watercore, and one from ‘Ralls Janet’ chr1 was related to low-mealiness. [ABSTRACT FROM AUTHOR]

Melon fruit properties are extremely different within the species and texture is one of the quality features that most influences its acceptance. The aim of this study was the comparison of melon textural traits, evaluating the linear correlations between both perceived and instrumentally determined texture of a distinctive group of genotypes representing wide species variability. Three landrace cultivars (the Korean ‘Songwhan charmi PI-161375’, the Indian ‘Calcuta PI-124112’, and the Iraqi ‘Irak C-1012’) and three elite cultivars (the Spanish ‘Piel de Sapo T111’, the French ‘Védrantais’, and the American ‘Dulce’), grown under the same conditions in the same place, were analyzed, together with four Spanish major commercial varieties (‘Piel de Sapo’, ‘Amarillo’, ‘Galia’ and ‘Cantaloupe’). Measurements of pH, Soluble Solids Content (SSC), weight losses, puncture tests (6 mm and 10 mm probes), texture profile analysis (TPA), and sensory analysis were performed in 38 fruits. Results showed wide parameter range depending on each particular type of melon. Significant differences were reported for five of six sensory descriptors: hardness (1.52–4.91), initial juiciness (1.77–7.45), crunchiness (0.29–4.58), mealiness (0.41–6.37) and chewiness (2.91–5.27); and for seven of nine physical-chemical parameters: hardness (921.3–4519.0), fracturability (587.4–4280.7), cohesiveness (0.027– 0.061), adhesiveness (−15.7 to −105.0), pH (5.21–6.53), SSC (4.8–14.0) and weight losses (18.0–66.0). Puncture tests parameters were good predictors of sensory hardness, crunchiness and chewiness, while TPA gave further information about initial juiciness, fibrousness and mealiness. Discriminant analysis showed that initial juiciness and mealiness were the most discriminant variables while any instrumental parameter showed particular discriminate ability between samples. These results prove the usefulness of sensory analysis to reflect melon textural traits, when compared to single physical-chemical approach, and could be extended to the middle-late stages of variety development breeding programs. [ABSTRACT FROM AUTHOR]

An apple that is soft and lacks juiciness during consumption is characterized as a mealy fruit. Since mealiness in apple is considered as an undesirable quality parameter, this work aimed at developing classification models based on biospeckle imaging in order to recognize mealy from non-mealy apples. To evaluate the potential of biospeckle imaging in detection of mealiness, a total of 760 ‘Red Delicious’ apples were harvested. The 540 samples were stored under cold conditions for various time periods from 0 to 5 months. The remaining samples were kept at 20 °C and 95% relative humidity for 10–26 days. Biospeckle images of each apple were acquired at wavelengths of 680 and 780 nm, respectively. Biospeckle imaging was immediately followed by a confined compression test to measure fruit stiffness and juiciness. These parameters were used to categorize the samples into three classes called fresh, semi-mealy, and mealy. Results of clustering based on a self-organizing map showed that apple fruit are mealy when their stiffness and juiciness are less than 20 kN m −1 and 5 cm 2 , respectively. After classification of apples by destructive methods, time-historical speckle patterns were configured and biospeckle features such as the inertia moment, the absolute value of differences, and autocorrelation were extracted. Results showed that biospeckle activity for fresh samples was higher than semi-mealy and mealy. Finally, several neural network models were developed to classify apples. First, classification of apples into mealy and non-mealy classes was carried out, and then non-mealy apples were classified into fresh and semi-mealy classes. The best classification accuracy for fresh (81.7%) and semi-mealy (70.9%) apples were achieved at 780 nm. However, much better result (77.3% accuracy) for classification of mealy apples was observed at the wavelength of 680 nm. [ABSTRACT FROM AUTHOR]

Grain hardness is one of the most important quality characteristics of wheat (Triticum aestivum L.). It is a significant property of wheat grains and relates to milling quality and end product quality. Grain hardness is caused by the presence of puroindoline genes (Pina and Pinb). A collection of 25 genotypes of wheat with unusual grain colour (blue aleurone, purple and white pericarp, yellow endosperm) was studied by polymerase chain reaction (PCR) for the diversity within Pina and Pinb (alleles: Pina-D1a, Pina-D1b, Pinb-D1a, Pinb-D1b, Pinb-D1c and Pinb-D1d). The endosperm structure was determined by a non-destructive method using light transflectance meter and grain hardness by a texture analyser. Genotype Novosibirskaya 67 and isogenic ANK lines revealed hitherto unknown alleles at the locus for the annealing of primers of Pinb-D1. Allele Pinb-D1c was found to be absent from each genotype. The mealy endosperm ranged from 0 to 100 % and grain hardness from 15.10 to 26.87 N per sample. [ABSTRACT FROM AUTHOR]

The position of fruit within the pear tree canopy may affect fruit quality characteristics. The objective of this study was to determine whether outer and inner canopy ‘Forelle’ pears differ in quality attributes and how these differences relate to consumer preference when stored for 9, 12 and 16 weeks at −0.5 °C in air and ripened for 7 days at 20 °C. Fruit firmness, size, colour, total soluble solids concentration (TSS), titratable acidity (TA), internal ethylene concentration, dry matter concentration (DMC) as well as the incidence of mealiness were determined after each cold storage period and subsequent ripening. The flavour and texture of the pear samples were assessed by a trained panel and consumer groups scored pears for eating quality and appearance. In 2011, inner canopy pears that were cold stored for 12 and 16 weeks and ripened were preferred for eating quality. Mealiness was generally low in inner canopy pears and significantly lower than in outer canopy pears. Mealiness was low for both canopy positions after 16 weeks cold storage plus ripening. While the preference for inner canopy pears after 12 weeks storage may relate to the lower incidence of mealiness, reasons for the preference after 16 weeks cold storage are uncertain. In 2012, the incidence of mealiness in outer canopy pears was double that of inner canopy pears, which may explain the general consumer preference for inner canopy pears. The canopy position effect was less in 2012 when fruit were picked at more optimal firmness (±6.4 kg) compared to harvesting at pre-optimum firmness (±7.9 kg) in 2011. Mealiness levels decreased from 9 and 12 weeks cold storage to 16 weeks cold storage in 2012. This study therefore supports the mandatory 12 weeks cold storage period at −0.5 °C for ‘Forelle’ pears to ensure optimum eating quality. In light of the above, inner canopy ‘Forelle’ pears should not be viewed as inferior to outer canopy pears. The consistent differences in mealiness incidence between inner and outer canopy ‘Forelle’ pears opens up a new avenue for investigating mealiness development. [ABSTRACT FROM AUTHOR]

Cold storage (CS) can induce a physiological disorder known as chilling injury (CI) in nectarine fruits. The main symptom is mealiness that is perceived as non-juicy fruit by consumers. Postharvest treatments such as controlled atmosphere (CA; a high CO2 concentration and low O2) have been used under cold conditions to avoid this disorder. With the objective of exploring the mechanisms involved in the CA effect on mealiness prevention, we analyzed transcriptomic changes under six conditions of "Red Pearl" nectarines by RNA-Seq. Our analysis included just harvested nectarines, juicy nonstored fruits, fruits affected for CI after CS and fruits stored in a combination of CA plus CS without CI phenotype. Nectarines stored in cold conditions combined with CA treatment resulted in less mealiness; we obtained 21.6% of juice content compared with just CS fruits (7.7%; mealy flesh). RNA-Seq data analyses were carried out to study the gene expression for different conditions assayed. During ripening, we detected that nectarines exposed to CA treatment expressed a similar number of genes compared with fruits that were not exposed to cold conditions. Firm fruits have more differentially expressed genes than soft fruits, which suggest that most important changes occur during CS. On the other hand, gene ontology analysis revealed enrichment mainly in metabolic and cellular processes. Differentially expressed genes analysis showed that low O2 concentrations combined with cold conditions slows the metabolic processes more than just the cold storage, resulting mainly in the suppression of primary metabolism and cold stress response. This is a significant step toward unraveling the molecular mechanism that explains the effectiveness of CA as a tool to prevent CI development on fruits. [ABSTRACT FROM AUTHOR]

In a number of ways, modern potato breeding efforts differ from those that created heirloom cultivars. As a result of the rapid expansion of the potato processing industry in the mid twentieth century, potato breeders shifted their focus from fresh market varieties to those intended for the fry and chip markets. Selection for higher dry matter content and lower reducing sugar levels in tubers was successful. This study sought to determine whether modern processing cultivars differ from heirloom cultivars for two major characteristics of tuber starch, amylose content and starch granule morphology. Since breeding efforts for processing potatoes have focused on the maintenance of tuber quality during storage, these parameters were measured in both fresh and stored tubers. Twenty cultivars selected to span the range of cultivar release dates in the U.S. were grown at Hancock, WI in 2009 and 2010 and evaluated for tuber amylose content and measurements of starch granule surface area, length, width, length to width ratio, and smoothness. These traits were found to be stable across years and during storage. Significant differences in the amylose content and starch granule morphology exist among cultivars, but there is no clear distinction between modern and heirloom cultivars. Genetic variation for amylose content and starch granule morphology was found within the set of clones sampled for this study. However, germplasm with higher amylose content will need to be identified and utilized in breeding if the nutritional benefits associated with high fiber and low glycemic index are to be realized. [ABSTRACT FROM AUTHOR]

Apricots (Prunus armeniaca) were held in air storage at 0°C and ripened at 20°C, or ripened at 20°C straight after harvest, and changes in fruit quality quantified using postharvest and sensory evaluations. Maturity at harvest significantly affected flesh firmness and other quality factors. Mealiness and gel formation only developed in fruit that had been stored at low (0°C) temperatures. Mealiness did not develop until firmness dropped below approximately 20N, whereas gel formation began to develop when firmness was as high as 35N. Development of mealiness and loss of juiciness were correlated; however, slight mealiness was perceived when fruit were still considered juicy. Specific cultivar-related differences were evident in the changes in firmness and development of gel formation during and after cold storage. Fruit were less liked by the sensory panel when firmness dropped below 20N, as juiciness decreased and mealiness and gel formation increased. Cell wall studies showed changes in yields of water-soluble and CDTA (trans-1,2-cyclohexanediamine tetraacetic acid)-soluble pectin. In fruit ripened after cold storage, mealiness and gel formation was accompanied by an increase in water-soluble pectin and an increase in CDTA-soluble pectin, whereas in apricots ripened straight after harvest, water-soluble pectin increased but CDTA-soluble pectin slightly decreased. All fruit, regardless of maturity or having chilling disorders or not, fitted the same correlation between firmness and uronic acid content of water-soluble pectin, but no pattern was evident for CDTA-soluble pectin. We concluded that the increasing solubilisation of pectin was a major feature of fruit softening in apricot, whereas the differences in CDTA-soluble pectin may reflect differences in strength of cell adhesion. [ABSTRACT FROM AUTHOR]

Abstract: Hyperspectral scattering images between 600nm and 1000nm were acquired for 580 ‘Delicious’ apples for mealiness classification. A locally linear embedding (LLE) algorithm was developed to extract features directly from the hyperspectral scattering image data. Partial least squares discriminant analysis (PLSDA) and support vector machine (SVM) were applied to develop classification models based on the LLE, mean-LLE and mean spectra algorithms. The model based on the LLE algorithm achieved an overall classification accuracy of 80.4%, compared with 76.2% by the mean-LLE algorithm and 73.0% by the mean spectra method for two-class classification (i.e., mealy and nonmealy) coupled with PLSDA. For the SVM models, the LLE algorithm had an overall classification accuracy of 82.5%, compared with 79.4% by the mean-LLE algorithm and 78.3% by the mean spectra method. Hence, the LLE algorithm provided an effective means to extract hyperspectral scattering features for mealiness classification. [Copyright &y& Elsevier]

Chilling injury (CI) is a major physiological problem limiting consumption and export of peach and nectarine ( Prunus persica (L.) Batsch). To clarify the genetic basis for chilling injury, inheritance of the major CI symptoms mealiness, flesh browning, flesh bleeding, and flesh leatheriness were examined over three years in two related peach progenies. In addition, genetic relationships among traits and the year-to-year variation in trait performance in these progenies were tracked. Both populations also segregated for Freestone-Melting flesh ( F- M) and yellow flesh. There were significant differences in CI symptoms among years. The major gene endoPG, which controls the F- M locus, provides resistance to mealiness in non-melting flesh fruit. Only fruit with melting flesh can develop mealiness if the tree possesses other genetic susceptibility factors and/or experiences inducing conditions. The F- M locus also greatly influences susceptibility to flesh bleeding, although the physiological mechanism for this disorder is unclear and may be controlled by a different gene closely linked to endoPG. Unlike mealiness, flesh bleeding occurred primarily in non-melting flesh fruit, particularly when the fruit is white-fleshed. Flesh browning incidence was greater in mealy fruit and was not associated with flesh bleeding. Breeding for CI resistance is thus a viable long-term strategy to reduce losses in the fresh and processed peach and nectarine industries. This study is an important first step to understanding genetic control of CI symptoms in peach. [ABSTRACT FROM AUTHOR]

In order to investigate the genetic bases of the physiological syndrome mealiness that causes abnormal fruit softening and juice loss in apples, an integrative approach was devised, consisting of sensory, instrumental, biochemical, genetic, and genomic methods. High levels of activity of α-L-arabinofuranosidase (α-AFase), a hydrolase acting on the pectic component of the cell walls, were found in individuals exhibiting the mealiness phenotype in a segregating population. The expression levels of the previously uncharacterized apple AF gene MdAF3 are higher in fruits from plants consistently showing mealiness symptons and high α-AFase activity. The transcription of MdAF3 is differentially regulated in distinct genomic contexts and appears to be independent of ethylene. Thus, it is likely to be controlled by endogenous developmental mechanisms associated with fruit ripening. The use of integrative approaches has allowed the identification of a novel contributor to the mealiness phenotype in apple and it has been possible to overcome the problems posed by the unavailability of near-isogenic lines to dissect the genetic bases of a complex physiological trait in woody perennial species. [ABSTRACT FROM PUBLISHER]

Abstract: Nectarine fruit after cold storage soften normally, but become dry instead of juicy and can develop flesh browning, bleeding and a gel-like or glassy formation of the flesh near the pit. An experiment was conducted to see if time-resolved reflectance spectroscopy could distinguish these internal disorders non-destructively. The optical parameters of absorption coefficient (μ a) and reduced scattering coefficient (μ′s) were measured at 670nm and 780nm, on nectarine (Prunus persica cv. Morsiani 90) fruit held at 20°C after harvest or after 30 d of storage at 0°C or 4°C. Each day for 5 d 30 fruit were examined both non-destructively and destructively. Other measurements were firmness with a penetrometer, peel colour on the blush and non-blush side, expressible juice, weight loss, and visual rating of internal browning, bleeding, and gel. The fruit had been sorted at harvest according to the value of μ a670 so that each batch had a similar spread of fruit maturity. More mature fruit (lower μ a670 values) developed internal browning and bleeding with more severe symptoms compared to less mature ones (higher μ a670 values). It was found that μ a780 could distinguish healthy fruits from the chilling injured ones. Canonical discriminant analysis indicated that fruit without cold storage had low μ a780, less water loss, low firmness, but high μ a670 and high expressible juice compared with cool stored fruit. Fruit cool stored at 4°C had high μ a780 and less expressible juice, lower water loss and lower firmness compared with fruit cool stored at 0°C. It was concluded that time resolved reflectance spectroscopy could detect internal woolliness and internal browning in nectarines after storage. [ABSTRACT FROM AUTHOR]

Abstract: Mealiness is a symptom of fruit physiological disorder, which is characterized by abnormal softness and lack of free juice in the fruit. This research investigated the potential of hyperspectral scattering technique for detecting mealy apples. Spectral scattering profiles between 600 and 1000nm were acquired, using a hyperspectral imaging system, for ‘Red Delicious’ apples that either had been kept in refrigerated air at 4°C or undergone mealiness treatment at 20°C and 95% relative humidity for various time periods of 0–5 weeks. The spectral scattering profiles at individual wavelengths were quantified by relative mean reflectance for 10mm scattering distance for the test apples. The mealiness of the apples was determined by the hardness and juiciness measurements from destructive confined compression tests. Prediction models for hardness and juiciness were developed using partial least squares regression (PLS); they had low correlation with the destructive measurement (r ≤0.76 for hardness and r ≤0.54 for juiciness). Moreover, PLS discriminant models were built for two-class (‘mealy’ and ‘nonmealy’), three-class (‘mealy’, ‘semi-mealy’ and ‘fresh’) and four-class (‘mealy’, ‘soft’, ‘dry’, and ‘fresh’) classification. The overall classification accuracies for the two classes of ‘nonmealy’ and ‘mealy’ apples were between 74.6% and 86.7%, while the overall accuracies in the three-class classification ranged between 60.2% and 71.2%. Much better results (≥93% accuracy) were achieved for the two-class classification of ‘mealy’ apples that had undergone longer time of mealiness treatment (i.e., 4–5 weeks of storage at 20°C and 95% relative humidity). Hyperspectral scattering technique is potentially useful for nondestructive detection of apple mealiness; however, improvements in classification accuracy are needed. [Copyright &y& Elsevier]

Abstract: Chilling injury (CI) is the collective term for various disorders that occur during prolonged cold storage and/or after subsequent ripening of stone fruit. Major symptoms of CI include mealiness, graininess, flesh browning, loss of flavor (off flavor), and red pigmentation (bleeding). These symptoms were evaluated over 2 years in an intra-specific progeny population derived from the cross of cultivars ‘Venus’ (freestone, melting and yellow-flesh nectarine) and ‘BigTop’ (clingstone, melting and yellow-flesh nectarine) after storage of fruit at 5°C (CI inducing conditions) for 2 and 4 weeks. All the evaluated traits in the progeny showed continuous variation which is typical of quantitative or polygenic inheritance. Longer cold storage periods increased the incidence and severity of CI symptoms, except for bleeding and leatheriness, which were not affected by time of storage. CI symptoms showed high and significant heritability or genotype effect in the studied population, with no significant effect of harvesting year. Browning, mealiness and graininess were significantly correlated and were the main CI symptoms observed in this population. Mealiness and graininess were negatively correlated with stone adhesion which reflects the higher susceptibility to CI disorders of freestone fruit. A genetic linkage map of linkage group 4 (LG4) was constructed with SSR and candidate genes (CGs). Significant quantitative trait loci (QTLs) for mealiness, graininess, leatheriness and bleeding were found in this linkage group, validating QTLs for CI symptoms previously reported in this linkage group from an unrelated progeny population. In addition, QTLs controlling other agronomic and fruit quality traits were also localized in this linkage group. [ABSTRACT FROM AUTHOR]

Abstract: Peaches are highly perishable; they ripen and deteriorate quickly at ambient temperature, and cold storage is used to slow these processes. The cell wall protein composition of two peach cultivars, and total protein composition were examined at harvest and after cold storage (3 weeks, 5°C) by two-dimensional polyacrylamide gel electrophoresis. The two peach cultivars used were ‘Oded’, a white-, melting-flesh, cling-stone, early season cultivar resistant to chilling injury, and ‘Hermoza’, a white-, melting-flesh, free-stone, mid-season cultivar susceptible to chilling injury. Following storage, peptides in the cell wall with molecular masses ranging from 18kDa to 60kDa were identified by amino acid sequence to be thaumatin-like protein 1 precursor and thaumatin-like protein 2 precursor. qRT-PCR analysis revealed that the thaumatin-like protein 1 precursor transcript accumulated significantly in both cultivars during storage. However, after 1 and 2 weeks of cold storage at 5°C the thaumatin-like protein 1 precursor transcript levels were significantly higher in the chilling injury-resistant peach ‘Oded’ than the susceptible peach ‘Hermoza’. This early accumulation of the thaumatin-like protein 1 precursor transcript in the resistant peach suggests that thaumatin-like protein 1 precursor (and perhaps thaumatin-like protein 2 precursor) might be involved in protecting against chilling injury. Although thaumatin-like proteins accumulated to high levels in cell walls of chilling injury-sensitive ‘Hermoza’, the kinetics of transcript accumulation suggest that the early appearance of the transcript for this protein family might be involved in shielding the fruit from the dramatic cell wall-structure changes that accompany the onset of chilling injury in stone fruit, and that result in woolliness development. [Copyright &y& Elsevier]

Information on texture of steam-cooked potato is of increased importance for consumers of fresh potatoes. As potato texture not only depends on genetic disposition but also on growth conditions, simple and reliable methods are needed to improve characterization of single potato lots. In the present study 65 potato lots were fractionized to 192 tuber samples according to their specific gravity and used for sensory evaluations. The aim was: (1) to further clarify the role of tuber specific gravity, variety and growth condition for texture attributes; and (2) to develop statistical models to predict potato texture objectively and reliably. Texture attributes varied considerably within varieties. The attributes mealiness, dryness, graininess were closely interrelated. Within the varieties, the three attributes as well as sloughing correlated with specific gravity (r = 0.78–0.96). Thus, they were predicted by specific gravity using variety-dependent models. Alternatively, using variety-independent models mealiness was predicted by the two parameters specific gravity and sloughing. Softness was related to the variety, but not to specific gravity. The statistical models may be helpful in optimizing the allocation of individual potato lots to specific cooking types for the retail market and for processing. PRACTICAL APPLICATIONS Information on texture of steam-cooked potato is of increased importance for consumers of fresh potatoes. We were approached by the potato industry to develop simple and reliable methods for characterization of single potato lots in trade. The objective measurement of texture by instrumental methods is rarely performed for routine testing, probably because of the laborious procedures. The measurement of tuber specific gravity is very simple. However, the relationship between specific gravity and various texture attributes is still not clear. We elaborate the relationship in an extensive evaluation using a broad range of potato lots. The models presented here may be applied directly for routine testing. We also suggest adaptations for routine calibration of new varieties and for routine testing of single lots. Further, the study encourages the scale-up of technologies which allow the grading of potatoes according to their specific gravity and thereby increase significantly texture homogeneity. [ABSTRACT FROM AUTHOR]

Abstract: The melting peach cultivar “Akatsuki” [Prunus persica L. Batsh] develops melting texture during ripening, but the stony-hard peach cultivar “Odoroki”, softens and develops a mealy texture when treated with propylene. Cell wall polysaccharides were fractionated as 1,2-diaminocyclohexanetetraacetic acid (CDTA)-, Na2CO3-, NaOH-soluble fractions, or the cellulosic residues that remained after solvent extraction. Size-exclusion chromatography of the CDTA-soluble fraction revealed a limited depolymerization of polyuronides in mealy “Odoroki” fruit, accompanying a lower level of endo-polygalacturonase (endo-PG) and a higher level of exo-PG activities compared to melting “Akatsuki” fruit. “Akatsuki” fruit showed increases in the arabinose, galactose and rhamnose contents in the CDTA-soluble fraction. These neutral sugars decreased in the Na2CO3-soluble and cellulosic residue fractions during ripening. Similar changes were observed for neutral sugars other than arabinose during softening in mealy “Odoroki” fruit. Arabinose content did not increase in the CDTA-soluble fraction of “Odoroki” fruit; however, arabinose content decreased in the Na2CO3-soluble fraction and in the cellulosic residue as observed for “Akatsuki” fruit. A significant increase in α-l-arabinofuranosidase activity, about 10 times higher than for “Akatsuki” fruit, was observed in propylene-treated mealy “Odoroki” fruit. Differences in ripening-associated metabolic changes in the cell walls of these peach cultivars seem to be related to their differences in texture. [Copyright &y& Elsevier]

• Friction measurements correlated strongly with crisp, juicy and mealy across years. • Penetrometry produced strong correlations with crisp. • Penetrometry had only weak to moderate correlations with juicy and mealy. • Penetrometer correlations were more variable across years. • Friction measurement is complementary to penetrometry, particularly in lab settings. Penetrometer measures are widely used to measure apple firmness to estimate texture attributes such as crispness during apple evaluation. Unfortunately, other texture attributes particularly those related to mouthfeel, such as juiciness and mealiness, are not well captured by this approach. The present study investigated correlations between friction measurements completed on a friction rig attached to a Texture Analyzer and apple texture attributes. The results are compared to the performance of penetrometry using a Magness-Taylor probe attached to a Texture analyzer over the course of several harvest seasons. Results indicated that the friction rig produced moderate to strong correlations (0.68 to 0.76) with apple crispness, juiciness and mealiness and correlations were consistently observed across years. In agreement with previous work, correlations between friction measurements and texture attributes were strongest during the earlier strokes of the friction runs indicating that short runs would be effective. Penetrometer measurements completed on the same apple sets produced moderate to strong correlations (0.60-0.87) with crispness. However, correlations with mouthfeel attributes (juicy and mealy) were lower (0.37-0.68). Penetrometers have certain advantages such as being low cost and they can also be used in-field. However, friction measurement is recommended as a complementary tool that can be used in more advanced stages of apple screening once samples are brought into the lab from the orchard and a more complete assessment of apple texture is needed. [ABSTRACT FROM AUTHOR]

Abstract: Electromyography (EMG) of the masticatory muscles was compared with puncture testing and sensory evaluation, in a study of the textural properties of Red Delicious apples. An aim of the work was to use EMG in predictive models of sensory mealiness, as this property is strongly negatively associated with apple acceptability. It was found that subjects’ EMG sensitivity and repeatability are as good as, and frequently better, than their sensory sensitivity and reliability. In addition to systematic effects associated with data recording session and subject, EMG data was also systematically affected by subjects’ behavioural changes, specifically, the sensory evaluation being undertaken. Once these unwanted sources of variance were removed using suitable data pre-treatment, frequency-domain EMG data were correlated with puncture test data, and a significant relationship obtained for six out of thirteen subjects. For five out of these six subjects, the strength of this relationship was improved by making use only of higher frequencies (>15Hz) in the EMG spectrum. EMG and puncture test data were each correlated with the sensory data. The nature of these relationships, in which the EMG frequency dependence effect was also clearly exhibited, demonstrated substantial common information content between the techniques. Finally, EMG and puncture test data were collectively used to model sensory mealiness, using univariate, bivariate and stepwise regression. Highly significant models were obtained for all but one subject’s sensory mealiness scores. In most cases, the best models used combinations of puncture test and EMG data from up to two of the four available electrodes. [Copyright &y& Elsevier]

Changes in turgor and flesh firmness during storage at 20 °C were investigated using 27 apple (Malus xdomestica Borkh.) cultivars for 2 years. Flesh firmness was measured using a penetrometer, and turgor was determined using a thermocouple psychrometer. Firmness and turgor of fruit decreased during storage. The cultivars with little softening during storage had low rates of reduction in turgor. The softening rates in mealy cultivars were high, but there were cultivars with low rates of turgor reduction. When the rates of reduction in turgor after harvest were low, the mealy cultivars of the fruit tended to develop severe mealiness during storage. Therefore, a low rate of reduction in turgor could contribute to cultivars with both good shelf life and severe mealiness. The reduction rates of turgor in progeny cultivars were nearly identical to the mean reduction rates of turgor of their parents. This suggests that a cultivar with a low reduction rate of turgor, although it can be mealy, has the potential to produce a progeny with a low reduction rate of turgor. [ABSTRACT FROM AUTHOR]

The internal sub-cellular physiological changes associated with ripening and mealiness in apples were investigated with novel two-dimensional NMR relaxation and diffusion techniques. It is shown that two-dimensional relaxometry reveals more subtle physiological changes than hitherto observed with conventional one-dimensional relaxometry. In particular it is shown that the T 1 of the peak associated with the cell wall in mealy apples is much longer than that of fresh apples. These changes could, perhaps, be exploited in the development of on-line NMR sensors of fruit quality. [Copyright &y& Elsevier]

Abstract: The aim of this study was to analyze the changes in cell wall pectins in normally ripening (juicy) and in chilling-injured plum fruit (Prunus salicina cv. Fortune) showing mealiness. Total cell wall neutral sugars and uronic acids, solubilization and depolymerization of pectins in water-, CDTA- and Na2CO3-soluble fractions of the cell wall (WSF, CSF and NSF, respectively), non-cellulosic neutral sugar compositions of these fractions, and the activities of the cell wall-degrading enzymes polygalacturonase (PG), pectin methylesterase (PME), 1,4-β-d-glucanase/glucosidase and β-galactosidase (β-gal) were determined. No differences in the total content of pectin and neutral sugars between normally ripening and chilling-injured fruit were detected. However, the mealy plums presented a higher level of tightly bound pectin (NSF) and a lower proportion of loosely bound pectin (WSF) than the juicy controls. Lower pectin depolymerization and reduced solubilization of neutral sugars in the WSF and CSF were also detected in the chilling-injured tissues, confirming an alteration in the normal ripening-associated pattern of polyuronide disassembly. While no differences were found in the activities of PG, PME and 1,4-β-d-glucanase/glucosidase between normally ripening and mealy fruit, the latter had reduced β-gal activity. This might have led to differential solubilization of polymers with galactan side chains, but further studies are required to determine if there is a causal relationship between these events. Overall, results indicated that the development of chilling injury symptoms in ‘Fortune’ plums is associated with abnormalities in cell wall metabolism, including a reduction in pectin solubilization and depolymerization and decreased ripening-associated modification of galactose-rich pectin polymers. [Copyright &y& Elsevier]

Tomato texture is one of the critical components for the consumer's perception of fruit quality. Texture is a complex character composed of several attributes that are difficult to evaluate and which change during fruit ripening. This study investigated the texture of tomato fruits at the rheological, sensory, morphological, and genetic levels, and attempted to correlate several parameters. Analyses were performed on tomato fruits from introgressed lines carrying quantitative trait loci (QTLs) associated with texture traits localized on different chromosomes, in two genetic backgrounds. Rheological measurements were used to determine resistance to deformation and fruit elasticity. Sensory analysis was used to assess flesh firmness, juiciness, mealiness, and skin toughness. Image analysis was used to study fruit morphology and to define the cellular structure and heterogeneity of the pericarp. A highly significant correlation was observed between instrumental and sensory firmness. Moreover, correlations were also established between some texture traits and parameters of the pericarp cellular structure. Compared with QTLs detected in a previous study, the phenotypic effects expected for mealiness were confirmed in all lines, whereas, for firmness, they were not confirmed. Significant interactions between QTL and genetic background were observed for several traits. In addition, kinetic analysis showed that differences in firmness occurred from the early stages of fruit development. These results provide both a broad description of texture components and preliminary information to understand their genetic control. [ABSTRACT FROM PUBLISHER]