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[Display omitted] • Hyperspectral data in Vis-NIR range was used to build calibration models for prediction of α-farnesene and CTols. • The best result for α-farnesene was obtained by LS-SVM model based on MSC-FD pretreatment with the RPD value of 2.6. • The optimal result for CTols (CT281) was achieved by LS-SVM model combined with SD pretreatment with PRD value of 2.4. The sesquiterpene α-farnesene and its corresponding oxidation products, namely conjugated trienols (CTols) is well known to be correlated with the development of superficial scald, a typical physiological disorder after a long term of cold storage in pear fruit. In this work, hyperspectral imaging (HSI) technology was used for nondestructive predicting of α-farnesene and CTols [CT258, CT281 and CT(281-290)] content in 'Yali' pear. In order to obtain the best performance of calibration model and simplify the calibration model further, various preprocessing methods together with their combinations and different wavelength selection algorithms, including successive projections algorithm (SPA), competitive adaptive reweighted sampling (CARS) and uninformative variable elimination (UVE), were investigated and compared based on linear partial least square regression (PLSR) and nonlinear least square support vector machine (LS-SVM) models, respectively. In conclusion, compared to the PLSR models, the results of LS-SVM models based on original and preprocessing methods performed better for the prediction of α -farnesene and CTols, while the performance of LS-SVM models based on the selected characteristic wavelengths were worse. For α-farnesene, the best result was obtained by LS-SVM model based on MSC-FD pretreatment with the RPD value of 2.6, R p = 0.925 and RMSEP = 4.387 nmol cm−2. And for CTols, CT281 performed better compared with CT258 and CT(281-290), achieving the result with RPD = 2.4, R p = 0.913 and RMSEP = 2.734 nmol cm−2 based on LS-SVM model combined with SD pretreatment. The overall results illustrated HSI technology could be used for rapid and nondestructive prediction of α-farnesene and CTols in 'Yali' pear, which would be helpful for supporting postharvest decision systems. [ABSTRACT FROM AUTHOR]

Superficial scald is a postharvest physiological disorder that occurs in pear during and after cold storage. In this study, the superficial scald index; α-farnesene and its oxidation products, conjugated trienols (CTols); phenolic content; and the expression of its related genes were investigated in two different pear cultivars, 'Wujiuxiang' (Pyrus communis L.) and 'Yali' (Pyrus bretschneideri R.), following 115 days of cold storage at 0 °C followed by 7 days of shelf life at 20 °C. The results indicated that the superficial scald occurred after 115 days of cold storage and became more severe during the shelf life of the 'Wujiuxiang' pear, whereas no scald was observed in 'Yali'. The α-farnesene levels increased rapidly at first and then decreased, while the CTols contents increased significantly in 'Wujiuxiang' as compared to 'Yali', and the expression levels of the genes involved in α-farnesene and CTols metabolism (HMGR1, HMGR2, GSTU7, GPX5, and GPX6), as well as the phenolic synthesis (PAL1, PAL2, C4H1, 4CL2, C3H, and ANR) of the peel, were significantly up-regulated at the onset of the superficial scald. In addition, the relative conductivity and contents of catechin and epicatechin were higher, and the expression level of the laccase gene (LAC7) significantly increased with the development of superficial scald, while lower contents of chlorogenic acid, arbutin, and isorhamnetin-3-3-glucoside, as well as the lower expression levels of a phenolic-synthesis-related gene (C4H3) and polyphenol oxidase genes (PPO1 and PPO5), were noticed in 'Wujiuxiang' as compared to 'Yali'. The results indicated that the onset and progression of superficial scald were associated with the accumulation of CTols, cell membrane breakdown, and higher catechin, epicatechin, and rutin contents, as well as the expression of associated genes of the peels of pear fruit. [ABSTRACT FROM AUTHOR]

Highlights • The link between biochemical factors and programmed cell death and scald severity is unknown. • Changes in these factors at various temperatures and durations were studied. • During low-temperature storage, scald developed quickly. • Scald increases in proportion with storage time. • Scald is closely associated with conjugated trienols and programmed cell death. Abstract Superficial scald is a physiological disorder affecting apple fruit during cold storage. Previous studies have reported that multiple factors, such as α-farnesene, ethylene, conjugated trienols (CTols), reactive oxygen species (ROS), and programmed cell death (PCD) are associated with superficial scald. However, the correlation between the factors and scald severity under different storage durations has rarely been reported. In this study, we analyzed how these factors change over time (0 d, 7 d, 30 d, 60 d and 90 d) in association with the incidence of scald in 'White Winter Pearmain' apples at low-temperature (5 °C). The results showed that the time for scald to development is short and the incidence of scald increases with storage time. The highest level of α-farnesene was observed after 7 d, whereas, the production rate of CTols, O 2 −, H 2 O 2, and ethylene gradually increased with time. In addition, specific expression profiling of MdDAD1 , MdLSD1 and MdDND1 suggested that PCD was involved with scald development. The correlation analysis showed that content of CTols, the production rate of ethylene, and the expression of MdAFS , MdHMGR2 , MdACS1 , MdACO1 , MdDAD1 , and MdLSD1 were strongly associated with superficial scald, whereas, α-farnesene and ROS were weakly associated. These results suggest that CTols and PCD are associated with scald development and that their role is more prominent than ROS. This is a novel perspective on the cause of scald that-can help develop potential solutions to inhibit scald development. [ABSTRACT FROM AUTHOR]

Influence of preharvest sunlight exposure on superficial scald development in ‘d’Anjou’ pears during cold storage was investigated. The biochemical changes related to scald including α-farnesene, conjugated trienols (CTols), antioxidants, antioxidant enzyme activities were monitored among separated blushed and shaded peels of unbagged fruit as well as the whole peel of bagged fruit. In unbagged fruit, scald symptom was restricted to shaded peel; while there was no difference in α-farnesene between blushed and shaded peels, CTols increased significantly in shaded peel along with scald development after 3 months storage. Bagging treatment increased both α-farnesene and CTols significantly and enhanced scald. Preharvest sunlight exposure significantly increased certain antioxidant contents and antioxidant enzyme activities in blushed peel at harvest and during storage. These results reveal a direct role of CTols during development of scald, however, antioxidant systems may play an important role in α-farnesene oxidation to CTols and scald susceptibility in ‘d’Anjou pears. [ABSTRACT FROM AUTHOR]

To assess the influence of the fruit maturity at harvest on superficial scald incidence, ‘Beurré D’Anjou’ pears were harvested on January 24 (H 1 ); February 7 (H 2 ) and February 21 (H 3 ). Ethylene production, α-farnesene (AF), conjugated trienols (CTols) content and total antioxidant capacity (DPPH) were determined at harvest and during storage and further related to superficial scald (SS) development. Early picked fruit (H 1 ) had significantly lower scald incidence than H 2 or H 3 . The difference in scald sensitivity between harvests was associated to the capacity of the fruit to produce ethylene and to the accumulation pattern of AF and CTols, which in turn was not exclusively ethylene-dependent. Collectively the results presented herein showed that the relationship between scald and maturity in ‘Beurré D’Anjou’ pears may be opposite to that observed in apples. Changes in the fruit antioxidant capacity during storage rather than the initial antioxidant potential at harvest should be considered to fully understand the biochemical basis of superficial scald in ‘Beurré D’Anjou’ pears. [ABSTRACT FROM AUTHOR]

Abstract: The effects of 1-methylcyclopropene (1-MCP) on ripening, superficial scald and concentrations of α-farnesene, conjugated trienols (CTols) and antioxidant enzyme activity of ‘KS6’ Asian pear (Pyrus serotina Rehd.) were studied. 1-MCP treated (2μLL−1) or untreated control fruit were stored at 1°C and 90–95% RH for up to 120 days. 1-MCP treated fruit were firmer than untreated fruit. Application of 1-MCP delayed skin color change. Scald appeared after shorter storage duration and was reduced, but not entirely controlled, with 1-MCP. Accumulation of α-farnesene and oxidation were slower in skin of 1-MCP treated fruit compared with controls. Catalase and peroxidase activities in untreated fruit either increased while activities decreased in 1-MCP treated fruit. Superoxide dismutase activity remained stable. The treatment of Asian pears with 1-MCP followed by cold storage maintained textural characteristics with less scald incidence. [ABSTRACT FROM AUTHOR]

Abstract: ‘Bartlett’ pears grown in northern California (CA) consistently show development of the physiological storage disorder superficial scald, particularly after prolonged storage of 4–5 months in air. In contrast, fruit of this cultivar grown in central Washington (WA) are typically less susceptible to scald, exhibiting mild or no symptoms. Conjugated triene (CT) oxidation products of the sesquiterpene α-farnesene are thought to play a key role in scald induction in apples and pears. This study compared accumulation of α-farnesene and its CT products in peel tissue of CA- and WA-grown ‘Bartlett’ pears during air storage at −1°C in relation to scald development after transfer to 20°C. Pears were harvested from commercial orchards in 2006 and 2007 and stored under nearly identical conditions for up to 24 weeks. Peel tissue samples taken at harvest and at 2–4-week interval during storage were analyzed by HPLC to determine concentrations of α-farnesene and CTs. Measurements of flesh firmness, respiration, and ethylene production were also made at harvest and/or from 1 to 8d after removal from storage to 20°C. WA fruit from the second harvest in 2006 developed light superficial scald after 20 weeks of cold storage plus 5d at 20°C; all others were scald-free. By contrast, all CA fruit from both seasons showed light scald after 12–14 weeks, and moderate scald after 20–24 weeks, plus shelf life. Correspondingly, α-farnesene and CTs accumulated more rapidly and on average reached about twofold higher concentrations in CA compared with WA fruit over the first 8–12 weeks of storage. CA fruit also had an earlier rise in ethylene production, higher respiratory rates, and lower flesh firmness at harvest than WA fruit. These suggest advanced maturity, which may have contributed to the increased rates of α-farnesene synthesis and oxidation, and higher incidence of scald. [Copyright &y& Elsevier]

• Antioxidants and fermentative metabolites changed depending on storage conditions. • CA and ILOS differently affected the stress-related compounds of apple peel. • ILOS and CA induced an increase in reduced and total glutathione content. • The antioxidant system might play a protective role against postharvest disorders. Storage of apples (Malus × domestica, Borkh.) in controlled atmosphere (CA) and/or the application of initial low oxygen stress (ILOS) are very effective in controlling postharvest disorders as bitter pit and superficial scald. This work aims to evaluate the effect of CA-storage and ILOS on the stress-related compounds of apple peel and to deepen the knowledge about the possible role of the antioxidant defense system against postharvest disorders. Fermentative metabolites, ascorbate (ASA), glutathione (GSH), total ascorbate (T-ASA) and total glutathione (T-GSH), ethylene, α-farnesene, conjugated trienols (CTols), as well as standard maturity indices, were monitored on the peel of apples (cv Red Chief) subjected or not to ILOS and stored 120 days in air or CA. CA-storage caused a reduction of conjugated trienols and ethylene production in Red Chief fruit compared to storage in air. ILOS induced an increase in the production of fermentative metabolites, especially when coupled with CA-storage, but the observed increase in ethanol concentration did not affect ethylene production. ILOS pretreatment and CA-storage induced higher T-GSH and GSH content in the peel of Red Chief fruit. In particular, ILOS caused a temporary shift of GSH towards its oxidated form, which finally resulted in an induction of GSH biosynthesis. Given the positive effect of ILOS on the GSH and T-GSH content, we hypothesize that the peel antioxidant compounds might play some role in the protection against postharvest disorders. [ABSTRACT FROM AUTHOR]