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Red-fleshed apples are receiving increased attention because of their remarkable anthocyanin contents. To provide sufficient experimental evidence about their phenolic composition and strong antioxidant capacity, three red-fleshed varieties from Xinjiang, P.R. China and one from the USA were evaluated. For comparison, two commercial white-fleshed varieties were also included. In samples of the flesh, contents of phenolics (total phenolics, flavonoids, flavanols, and anthocyanins) and antioxidant activity were significantly higher for red-fleshed varieties than for white-fleshed varieties. Flavonoid profiles also differed between the red- and white-fleshed varieties. Among the red-fleshed varieties, ‘Roberts Crab’ had the highest amounts of total phenolics, flavonoids, and anthocyanins, as well as the strongest antioxidant activity, while ‘Xiahongrou’ had the lowest levels of total phenolics and flavonoids and the weakest activity. HPLC analysis revealed that individual phenolic compounds varied significantly among red-fleshed varieties. These results suggest that red-fleshed apples are a promising source of antioxidants for human nutrition. [ABSTRACT FROM AUTHOR]

Appropriate changes to the blade tip structure can effectively improve fan performance. The performance of the OB-84 axial fan with different grooved blade tips is simulated using Fluent. The effects of various tip structures on the flow field, losses distribution, and noise characteristics are investigated. Analysis of static structure and vibration characteristics is performed with the Ansys finite element analysis module. Simulated results show that for the grooved blade tips, both the total pressure rise and shaft power of the fan decrease, but the efficiency improves distinctly; the grooved blade tip structure perturbs the flow and vortex fields and impedes the development of the leakage flow; this eventually results in the reduction of mixing losses between the leakage flow and mainstream. Blade tip case 4 produces the maximum efficiency with an increase of 1.07% at design volume flow rate, and case 7 obtains the lowest shaft power compared with the original tip. Grooved blade tips amplify the fan noise, so measures should be taken to control the noise. Analysis of dynamic characteristics reveals that the distortion and fracture failure of the blade as well as resonance of the impeller would not occur by adopting grooved blade tips. [ABSTRACT FROM AUTHOR]

Abstract: Effects of light irradiation on the photosynthetic electron transport chain between P680 and P700 in apple tree leaves was probed with chlorophyll a fluorescence transient and 820 nm transmission measurements during dehydration under different light intensities. The results showed that light accelerated the leaf water-loss rate during dehydration. Leaf dehydration lowered the maximum quantum yield of PSII and the far-red light induced maximal transmission change at 820 nm, but increased the relative variable fluorescence intensity at J-step, especially under increasing irradiation conditions. During leaf dehydration, irradiation lowered the relative variable fluorescence intensity at I-step. At the beginning of leaf dehydration, moderate light accelerated the leaf water-loss rate and then lowered the maximal light-trapping efficiency of P680. Upon further dehydration under moderate light or dehydration under high light, light accelerated the water-loss rate and also directly decreased the maximal light-trapping efficiency of P680. The more significant decrease in the exchange capacity of plastoquinones at the QB site was mainly attributed to the faster water-loss rate under moderate light than in the dark. Under high light, irradiation also directly lowered the capacity. The reoxidation of PQH2 in the dehydrated leaves was enhanced by the light irradiation. The rapidly decreased contents of P700 + plastocyanin were mainly attributed to the faster water-loss rate under light conditions in contrast with that in the dark. The different effects of light irradiations on the photosynthetic electron transport chain might be involved in the acclimation of apple tree leaves to dehydration. [Copyright &y& Elsevier]

Abstract: The developmental changes of carbohydrates, organic acids, amino acids and phenolic compounds in ‘Honeycrisp’ apple flesh were investigated using GC–MS and HPLC. A total of 12 carbohydrates, 8 organic acids, 20 amino acids, and 18 phenolic compounds were identified and quantified. Each metabolite showed characteristic changes during fruit development, but in general, concentrations of most sugars and sugar alcohols either increased or remained unchanged whereas concentrations of most organic acids, amino acids and phenolic compounds decreased with fruit development, indicating that most sugars and sugar alcohols are synthesised and/or accumulate at a faster or similar rate relative to fruit growth whereas organic acids, amino acids and phenolics are synthesised and/or accumulate at a slower rate relative to fruit growth. On a whole fruit basis, the content of most metabolites increased with fruit development. In the flesh of mature ‘Honeycrisp’ apple, fructose and sucrose and sorbitol are the major sugars and sugar alcohol; malic acid is the major organic acid; aspartic acid, asparagine, glutamic acid, proline, threonine and γ-aminobutyric acid are the major amino acids; and procyanidin B1, procyanidin B2, chlorogenic acid, catechin and epicatechin are the major phenolic compounds, respectively. [Copyright &y& Elsevier]

Abstract: Pigments, chlorophyll fluorescence, dark respiration, and the antioxidant system in the shaded peel of green ‘Anjou’ pear (Pyrus communis L.) and its bud mutation, red ‘Anjou’, were compared in response to high peel temperature, high light alone or in combination to determine the protective role of anthocyanins under high temperature with or without light. Under high temperature treatment alone, no difference in the maximum quantum yield of PSII (F V/F M) was detected between red ‘Anjou’ and green ‘Anjou’; the superoxide dismutase activity and the glutathione pool were up-regulated in green ‘Anjou’ peel but remained unchanged in red ‘Anjou’ peel. Under high temperature coupled with high light, the F V/F M of green ‘Anjou’ peel was decreased to a lower value than that of red ‘Anjou’, and significant interaction was detected between temperature and light for both cultivars. Furthermore, the difference in F V/F M between red ‘Anjou’ and green ‘Anjou’ under high temperature coupled with high light was significantly larger than that under high light alone, indicating that this larger difference was caused by the interaction between high temperature and high light as no significant difference was detected in F V/F M between the two cultivars under high temperature treatment alone at any sampling point. It is concluded that the elevated anthocyanin level in the shaded peel of red ‘Anjou’ does not alter its thermotolerance in the dark, but makes it more tolerant of high temperature under high light. [Copyright &y& Elsevier]

Summary: The purpose of this study is to demonstrate the heterogeneous behavior of PSII in soybean (Glycine max) leaves and identical maximum PSII photochemistry efficiency (F V/F M) under different high temperature treatments. We observed that, with an identical decrease in F V/F M in soybean leaves caused by different high temperature treatments, chlorophyll a fluorescence differed significantly, indicating different behaviors in the photosynthetic apparatus. The quantitative analysis showed that, with an identical F V/F M, leaves treated at 48°C showed a higher W K, an indicator of damage to the oxygen-evolving complex along with a lower O2 evolution rate compared with leaves treated at 45°C. This demonstrated that the donor side of PSII was damaged more severely at 48°C than at 45°C despite the same decrease in F V/F M in the two heat-treated leaves. The ratios of Q A- and Q B-reducing PSII reaction centers to total PSII reaction centers were both lower in leaves treated at 48°C than in leaves treated at 45°C with an identical F V/F M, indicating that the acceptor side of PSII was also more damaged by heat treatment at 48°C than at 45°C. However, when damage to the donor side of PSII was similar in leaves treated at two different temperatures, the acceptor side of PSII was damaged less severely at 48°C, which accounted for higher electron transport rate at the acceptor side of PSII in leaves treated at 48°C than in leaves treated at 45°C. [Copyright &y& Elsevier]

The thermotolerance of the sun-exposed peel and the shaded peel of ‘Fuji’ apple (Malus domestica Borkh.) fruit was evaluated by measuring pigments, chlorophyll a fluorescence transients and O2 evolution or uptake after exposure to 25, 35, 40, 42, 44, 46 or 48°C for 30min in the dark. A major effect of heat stress at 46–48°C on the chlorophyll a fluorescence transients was the appearance of a very clear K step at 200–300μs for both peel types. The K step was slightly more pronounced in the sun-exposed peel than in the shaded peel, suggesting that the resistance of oxygen-evolving complex to heat stress is slightly lower in the sun-exposed peel than in the shaded peel. Minimal fluorescence (F O), relative to the value at 25°C, increased to a greater extent in the shaded peel than in the sun-exposed peel after exposure to 46–48°C, but the temperature dependencies of F O changes were similar for both peel types. Maximum quantum yield of PSII (F V/F M) decreased to a similar extent in the sun-exposed peel and the shaded peel as temperature rose from 25 to 44°C, but the sun-exposed peel reached slightly lower values at 46–48°C. Correspondingly, gross O2 evolution rate, relative to that at 25°C, was also slightly lower in the sun-exposed peel than in the shaded peel at 46–48°C. In response to heat stress, the ratio of QA-reducing reaction centers (RCs) to total RCs and the ratio of QB-reducing RCs to QA-reducing RCs decreased, but both of them decreased to lower values in the sun-exposed peel than in the shaded peel at 46–48°C, indicating that the capacity of electron transfer between P680 + and QB via QA was damaged to a greater extent in the sun-exposed peel than in the shaded peel. At each given temperature, dark respiration was... [Copyright &y& Elsevier]

Phloridzin (phloretin 2′- O -glucoside) is the most abundant phenolic compound in Malus species, accounting for up to 18% of the dry weight in leaves. Glycosylation of phloretin at the 2′ position is the last and key step in phloridzin biosynthesis. It is catalyzed by a uridine diphosphate (UDP)-glucose:phloretin 2′- O -glucosyltransferase (P2′GT), which directly determines the concentration of phloridzin. However, this process is poorly understood. We conducted a large-scale investigation of phloridzin accumulations in leaves from 64 Malus species and cultivars. To identify the responsible P2′GT, we performed a genome-wide analysis of the expression patterns of UDP-dependent glycosyltransferase genes ( UGT s). Two candidates were screened preliminarily in Malus spp. cv. Adams (North American Begonia). Results from further qRT-PCR analyses of the genotypes showed a divergence in phloridzin production. Our assays of enzyme activity also suggested that MdUGT88F4 and MdUGT88F1 regulate the conversion of phloretin to phloridzin in Malus plants. Finally, when they were silenced in ‘GL-3’ (‘Royal Gala’), the concentrations of phloridzin and phloretin (and trilobatin) were significantly reduced and increased, respectively. [ABSTRACT FROM AUTHOR]

The reverse transcription quantitative real-time polymerase chain reaction (qRT-PCR) technique has become one of the most widely used and reliable methods in gene expression studies. Successful application of qRT-PCR requires the accurate quantification of relative transcript levels, which strongly depends on the expression stability of the reference genes used as internal controls for data normalization. Plums ( Prunus salicina Lindl.) are among the most numerous and commercial important fruit trees. In order to ensure the reliability of gene expression analyses using qRT-PCR in plum molecular biology research, 14 candidate reference genes were selected, and their relative expression levels were further measured by qRT-PCR using samples of plum peels obtained via different postharvest processes. Three statistical algorithms, geNorm, NormFinder, and BestKeeper, were employed to assess the expression stability of each candidate gene. A comprehensive evaluation was generated by the overall analysis approach, RefFinder to infer the final rankings. The results showed that CAC was the most stably expressed candidate reference gene across all experimental conditions. CAC and UNK under the room temperature treatment, CAC , ACT , and CLATH under the cold treatment, and CAC and ACT under all treatments were suitable for accurate gene expression quantification. In addition, relative gene expression patterns of the plant anthocyanin biosynthesis-related structural gene PsANS were evaluated using selected housekeeping genes as internal controls under two treatments to further confirm the usefulness of the selected reference genes. These results indicated that the selection of systematically validated reference genes for specific experimental conditions is necessary to avoid misinterpretation of qRT-PCR data and to obtain accurate and reliable gene expression results. [ABSTRACT FROM AUTHOR]

Abstract: Fractions of absorbed light energy consumed via photochemistry and different thermal dissipation processes was quantified and compared between the sun-exposed peel and the shaded peel of apple fruits at different developmental stages. During fruit development, the fraction of absorbed light consumed via photochemistry was no more than 7% in the sun-exposed peel and no more than 5% in the shaded peel under high light conditions. Under high light, the fraction of absorbed light energy consumed via light dependent thermal dissipation was higher whereas that via constitutive thermal dissipation was lower in the sun-exposed peel. The light dependent thermal dissipation in the sun-exposed peel mainly depended on the xanthophyll cycle, and the xanthophyll cycle pool size was significantly larger in the sun-exposed peel than in the shaded peel. The light dependent thermal dissipation in the shaded peel was dependent on both the xanthophyll cycle and the presence of inactivated reaction centers. Under high light conditions, the densities of both QA-reducing reaction centers and QB-reducing reaction centers decreased faster in the shaded peel than in the sun-exposed peel. The thermal dissipation related to photoinhibition increased and then kept unchanged in the sun-exposed peel but decreased in the shaded peel during fruit development. We conclude that under high light intensities, fruit peel looses the excess energy in order of predominance: first by the xanthophyll cycle, then the thermal dissipation related to photoinhibition, next through inactivated reaction centers, and finally by constitutive thermal dissipation. [Copyright &y& Elsevier]

Highlights • Antioxidant capacities of dihydrochalcones were measured using DPPH or ABTS assays. • The 3,4- o -dihydroxyl and 2′-OH were critical for antioxidant activity. • Glycosylation enhanced antioxidant capacity. Abstract The antioxidant capacity (AC) of six dihydrochalcone compounds was evaluated using DPPH and ABTS assays. In water-based solution 3-hydroxyphlorizin exhibited the highest AC among all dihydrochalcones. In acetone and acidic solutions (pH = 2.5 or 2.0), presence of an o -dihydroxyl at the B-ring increased AC, whereas glycosylation at the A-ring decreased AC of dihydrochalcones. By comparing the AC of dihydrochalcones with similar structures, it was found that the o -dihydroxyl at the B-ring and 2′-hydroxyl group at the A-ring were critical for maintaining the AC of dihydrochalcones by promoting hydrogen atom transfer or single electron transfer mechanism. Sequential proton-loss electron transfer commonly occurred during free radical scavenging in water-based solution. Moreover, we report a unique phenomenon in which glycosylation at the 2′-position enhanced the dissociation ability of the 4′-hydroxyl group and increased the AC of dihydrochalcones containing o -dihydroxyl. We speculate that this increase in AC might occur through intramolecular electron transfer. [ABSTRACT FROM AUTHOR]

Five dihydrochalcone compounds, including phlorizin, trilobatin, 3-hydroxyphlorizin, sieboldin and phloretin 2′-xyloglucoside, were isolated from ornamental Malus ‘Red Splendor’ fruit. The chemical structures of these compounds were elucidated by LC-ESI-MS and NMR. Phloretin and 3-hydroxyphloretin were produced by hydrolysis. The antioxidant capacities of these seven compounds were examined by DPPH and ABTS assays, while their cytotoxicity to five cancer cell lines were evaluated by the MTT assay. The results showed that the DPPH assay mainly reflected the antioxidant capacity of the B ring, whereas the ABTS assay was mostly related to the A ring of the dihydrochalcone molecule. Moreover, 3-hydroxyphloretin was the best antioxidant among the seven compounds. Both glycosylation of the A ring and the ortho phenolic hydroxyl groups of the B ring were important for the cytotoxicity of dihydrochalcone molecules. Sieboldin and 3-hydroxyphlorizin exhibited better cytotoxicity than other dihydrochalcone compounds. Dihydrochalcones from Malus may benefit human health. [ABSTRACT FROM AUTHOR]

To investigate the effects of relative air humidity (AH) on ‘Fuji’ apple ( Malus domestica Borkh.) peel phenolic compounds and pigment coloration, the bagged fruits were bags moved and then exposed to high AH and low AH conditions, respectively. Cyanidin-3-galactoside, the main anthocyanin compound in apple, and 17 other types of phenolic compounds were detected and their concentrations were also compared between high and low AH treated apple peels. We observed that the removal of bags and subsequent re-exposure to sunlight could significantly decrease the concentrations of syringic acid, caffeic acid, ρ-coumaric acid, and quercetin-3-rhamnoside, but increase the concentrations of ferulic acid, quercetin-3-galactoside, quercetin-3-glucoside, quercetin-3-rutinoside, and cyanidin-3-galactoside. Furthermore, high AH samples had higher concentrations of chlorogenic acid, ferulic acid, epicatechin, quercetin-3-rutinoside, and cyanidin-3-galactoside than low AH samples as they were in the similar temperature conditions. These results suggested that high AH conditions could significantly improve coloration and the eating quality of fruits. [ABSTRACT FROM AUTHOR]

Highlights: [•] Phenolic extract from apple peel of ‘Golden Delicious’ can scavenge H2O2. [•] Anthocyanin contributes more to H2O2 scavenging than other phenolic compounds. [•] Less anthocyanin might be used to scavenge H2O2 in vivo than in vitro. [Copyright &y& Elsevier]

Highlights: [•] Responses of phenolics to fruit bagging and the following bag removal were studied. [•] Fruit bagging lowered the phenolic compounds concentration in apple peels. [•] The bag removal increased the concentrations of most phenolic compounds. [•] The compounds responded differently to fruit bagging and the following bag removal. [Copyright &y& Elsevier]