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.

As a traditional folk medicine, pear paste has important nutritional and health effects. The physicochemical properties and antioxidant activities of pear pastes prepared from 23 different cultivars were investigated, including color parameters ( L*, a*, b* and h°), transmittance, pH, titratable acidity (TA), soluble sugar content, total phenolics content (TPC), total flavonoids content (TFC), DPPH and ^•OH radical scavenging activity (RSA), and ferric reducing antioxidant power (FRAP). It was demonstrated that the physicochemical properties and antioxidant activities of pear pastes from various cultivars differed significantly. Pear cultivars of “Mantianhong”, “Xiangshui” and “Anli” possessing higher TPC and TFC exhibited excellent antioxidant activity determined by DPPH RSA, ^•OH RSA and FRAP, while the lowest TPC and TFC was observed for the cultivars of "Xueqing", "Nansui", "Hongxiangsu", and “Xinli No. 7”, which also demonstrated the poor antioxidant activity. Multivariate analyses, including factor and cluster analysis, were used for the quality evaluation and separation of pear pastes based on their physicochemical and antioxidant properties. Factor analysis reduced the above thirteen parameters to final four effective ones, i.e. DPPH RSA, color b*, FRAP and TA, and subsequently these four parameters were used to construct the comprehensive evaluation prediction model for evaluating the quality of pear pastes. The pear pastes could be separated into three clusters and differentiated for the diverse of pear cultivars via cluster analysis. Consistently, “Mantianhong”, “Xiangshui” and “Anli” pear with higher quality clustered into one group, in contrast, "Xueqing", "Nansui", "Hongxiangsu", and “Xinli No. 7” with lower quality clustered into the other group. It provided a theoretical method to evaluate the quality of pear paste and may help the fruit processing industry select the more suitable pear cultivars for pear paste making.

‘Huangguan’ pear (Pyrus bretschneideri Rehd. cv. Huangguan) is a widely planted cultivar in China. However, it is susceptible to core browning after harvest. In this study, aminoethoxyvinylglycine (AVG) was applied at 200 mg L⁻¹ one and two weeks prior to harvest, and its effects on fruit quality, ripening and core browning were investigated during fruit storage at ambient temperature (25 ± 1 °C). The results showed that there was higher firmness, soluble solids content (SSC) and titratable acid (TA) content, but a lower ethylene production rate and core browning index in AVG-treated fruit than in control (water). Compared with the control fruit, AVG treatment decreased the malondialdehyde (MDA) content and polyphenol oxidase (PPO) activity, delayed the peak of chlorogenic acid (CGA) content in the core tissue, and significantly inhibited the expression of genes such as ACC synthase (PbACS2, PbACS3a, PbACS5a and PbASC5b), ACC oxidase (PbACO1 and PbACO2), ethylene receptors (PbETR2 and PbERS1), ethylene response factor (PbERF1), phenylalanine ammonia lyase (PbPAL1), cinnamate 4-hydroxylase (PbC4H4), 4-hydroxycinnamoyl- CoA ligase (Pb4CL2), hydroxycinnamoyl- CoA shikimate hydroxycinnamoyl transferase (PbHCT1 and PbHCT3), and polyphenol oxidase (PbPPO1 and PbPPO5), as well as phospholipase D (PbPLD) and lipoxygenase (PbLOX1 and PbLOX5). Thus, these results suggested that the reduction in core browning by preharvest application of AVG might be due to an inhibitory effect on the expression of genes associated with ethylene biosynthesis and signaling pathways, CGA biosynthesis, PPO and cell membrane degradation in ‘Huangguan’ pear.

Apricots, known for their unique flavor and health advantages, experience external quality deterioration after harvest due to their climacteric characteristics, leading to a decrease in shelf life. This research examines the effects of 1-Methylcyclopropene (1-MCP) application on the post-harvest quality and volatile compound profiles of ‘Jizaohong’ apricots when stored under ambient conditions. After harvesting, apricots underwent treatment with 0.5, 1.0, and 1.5 µL L⁻¹ of 1-MCP for a duration of 24 h, subsequently being stored at ambient temperature (20 ± 1 °C). The results demonstrate that 1-MCP treatments reduced decay, respiration rates, and ethylene production, while also preserving fruit firmness and maintaining skin coloration. Furthermore, the application of 1-MCP markedly diminished the emission of volatile compounds in ‘Jizaohong’ apricots, while linear discriminant analysis (LDA) effectively distinguished between the treated fruits and the untreated controls. The correlation analysis revealed a relationship between the response values of the electronic nose and the quality of the fruit, supporting its potential for swift and non-invasive assessment. Among the concentrations evaluated, 1.0 µL L⁻¹ 1-MCP demonstrated the highest efficacy in minimizing decay and improving quality, whereas 1.5 µL L⁻¹ 1-MCP did not show notable variations in firmness or ethylene suppression. Thus, the application of 1.0 µL L⁻¹ 1-MCP after harvest serves as an effective method for preserving the quality of ‘Jizaohong’ apricots and prolonging their shelf life, while also enabling swift, non-invasive evaluations using the electronic nose.

‘Huangguan’ pear (Pyrus bretschneideri Rehd. cv. Huangguan) fruit is sensitive to chilling injury (CI), which exhibits peel browning spots (PBS) during cold storage. Dehydrin (DHN) is considered to be related to cold tolerance in plants, but its function in postharvest pear fruit during storage remains unclear. In this study, six PbDHNs (PbDHN1–6) genes were identified and characterized, and the PbDHN proteins were sorted into Y_nK_n, SK_n and Y_nSK_n according to the major conserved motifs related to the number and location of K-segments, S-segments, and Y-segments. In addition, there were five cold-responsive related cis-acting elements in the promoter region of the PbDHNs. The analysis of fruit quality suggested that compared with a storage temperature at 20 °C, a storage temperature of 0 °C results in CI in ‘Huangguan’ pear fruit, while a storage temperature of 10 °C and low temperature conditioning (LTC) alleviates the CI. Moreover, gene expression results indicated that the six PbDHNs were markedly enhanced at low temperatures, especially at 0 °C. The transcripts of PbDHN1, PbDHN4, PbDHN5 and PbDHN6 were also increased in the fruit stored at 10 °C, but they were lower than that at 0 °C except PbDHN5. Compared with low temperature storage at 0 °C, LTC treatment significantly depressed the expression of PbDHN1, PbDHN2, PbDHN3, PbDHN4, and PbDHN6, while enhanced the mRNA amount of PbDHN5. In conclusion, PbDHN1, PbDHN4, PbDHN5, and PbDHN6 were closely related to the CI, and LTC lowered the CI by down-regulating the expression of PbDHN1, PbDHN4, and PbDHN6 and by up-regulating PbDHN5 in ‘Huangguan’ pear fruit.

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 expression of its related genes were investigated in two pear cultivars, ‘Wujiuxiang’ (sensitive to scald) and ‘Yali’ (less sensitive to scald), following 115 days of cold storage at 0 °C and followed by 7 days shelf life at 20 °C. The results indicated that the superficial scald occurred after 115 days of cold storage and became more severe during shelf life in ‘Wujiuxiang’ pear, whereas no scald was observed in ‘Yali’, the α-farnesene levels increased rapidly at first and then decreased while CTols contents increased significantly in ‘Wujiuxiang’ as compared to ‘Yali’, and the expression levels of genes involved in α-farnesene and CTols metabolism ( HMGR 1 , HMGR 2 ), GSTU 7 , GPX 5 , and GPX 6 , as well as phenolic synthesis ( PAL 1 , PAL2 , C4H1 , 4 CL2 , C3H , and ANR ) of the peel were significantly up-regulated at the onset of superficial scald. In addition, the relative conductivity and contents of catechin and epicatechin were higher, and the expression level of laccase gene ( LAC7 ) was significantly increased with the development of superficial scald, while the 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’ than those in ‘Yali’. The results indicated that the onset and progression of superficial scald were associated with the accumulation of CTols, cell membrane permeability, higher catechin, epicatechin, and rutin contents and associated genes expression in pear fruit.