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Debittering of pomelo juice was conducted using 3.7 g of activated resin, resulting in a 36.8% reduction in bitterness without affecting the bioactive properties of juice. The debittered juice was then encapsulated with Moringa oleifera exudate at various ratios (1–5%), yielding a powder with a slightly rough surface. Total phenol content (TPC) increased by 46–56% compared to the debittered juice. Functional yoghurt containing encapsulates at concentrations of 1% and 2% demonstrated that the 2% concentration led to longer storage duration, resulting in increased acidity and syneresis compared to the control. TPC of the yoghurt (161.89–198.22 μg Gallic acid equivalent (GAE)/g) remained significantly higher (p < 0.05) than that of the control (47.15 μg GAE/g) and acacia gum-based yoghurt (141.89–171.37 μg GAE/g), decreasing with storage duration. Addition of encapsulates significantly altered the yoghurt's texture, resulting in lower firmness (0.57 to 0.64 N) compared to the control, while adhesiveness values remained comparable (6.33 to 6.25 g.s). The highest values of G' and G" were observed in samples containing 2% encapsulates with moringa compared to those with acacia gum. This study suggests potential avenues for further exploration in functional foods with enhanced health benefits. [Display omitted] • The resin method was used for debittering Pomelo juice (Citrus grandis L. Osbeck). • Debittered juice was freeze-dried using novel Moringa olifera gum exudate. • Encapsulates with 5% moringa gum yielded 79.12% but had irregular shapes, in contrast to those made with acacia gum. • Yoghurt was developed using encapsulated debittered pomelo juice (1% and 2%). • Yoghurt with 2% juice-moringa encapsulates had the lowest sensory score, yet exhibited the highest bioactive properties. [ABSTRACT FROM AUTHOR]

Liangpingyou, a well-known Chinese pomelo (Citrus grandis L.) variety, elicits a unique and uncharacterized numbing aftertaste. To understand the molecular bases and characteristics of the pomelo-induced numbing sensation, we first determined that hydroxyl sanshools, the major Sichuan pepper chemosensates, were not responsible via silylation-GC–MS analysis. Pomelo peel juice was then subjected to solid-phase extraction to form 4 fractions, and key sensory-active substances were screened via taste dilution analysis. Three simple coumarins, meranzin hydrate, isomeranzin, and marmin, were identified to induce numbing, which has not been previously reported. Sensory studies via extensively modified half-tongue tests and verification steps revealed recognition thresholds within 0.49–1.78, 0.32–1.56, and 0.43–1.46 μmol/L for numbness, pungency, and astringency, respectively. The temporal dominance trends showed the following taste notes: Meranzin hydrate–numbing dominated, isomeranzin–numbing and pungent, and marmin–astringent and numbing. Molecular docking analysis suggested that coumarins target the receptors TRPV1, TPRA1, and KCNK3 [Display omitted] • Pomelo numbing attributes, numbness, pungency, and astringency, are characterized • Coumarins e.g. meranzin hydrate instead of OH-sanshools are pomelo numb elicitors • Modified sensory analysis reduces cross-interaction & adaptation of orosensations • Recognition threshold and temporal dominance of coumarin attributes are obtained • Three numbing coumarins bind to chemoreceptors, TRPV1, TRPA1, and KCNK3 in silico. [ABSTRACT FROM AUTHOR]

[Display omitted] • The outer layer has good barrier and mechanical properties. • The inner layer has antioxidant activity or antimicrobial effects. • There was interfacial fusion between two layers with good biocompatibility. • Melatonin reduced the ineffective release of essential oils in the film. • The activity packaging film maintained the white mushrooms good quality. In order to improve the effectiveness of the active packaging, we aimed to develop an active packaging film with unidirectional sustained release, high barrier protection, and seamless attachment between the layers. An active film based on glutenin/tamarind gum loaded with the binary microemulsion of melatonin/pummelo essential oil (G/ T -M-E) with sustained release and combination effects of internal and external layers was prepared. The outer barrier layer exerted an excellent protective barrier effect after adding (3-chloropropyl) triethoxysilane, which effectively reduced external interference and the ineffective diffusion of active substances in the inner layer. The effective attachment of melatonin and essential oil layer in the G/ T -M-E film enhanced antioxidation, microorganism inhibition, and free-radical-scavenging properties, which effectively delayed the senescence of post-harvest white mushrooms. Furthermore, the G/ T -M-E exhibited excellent tensile strength, barrier capacity, and load-bearing strength, which had a potential, positive effect on food preservation. Therefore, this film is highly recommended for packaging purposes. [ABSTRACT FROM AUTHOR]

• 0.3% SA inhibited the activities and expression and of cell wall degrading enzymes. • SA retained higher cell wall components in pummelo fruit. • SA kept lower level of WSP content and reduced pectin hydrolyzation. • 0.3% SA treatment alleviated postharvest albedo softening of 'Jinshayou' pummelo via maintaining the cell wall structure. The regulatory mechanisms underlying the salicylic acid (SA)-mediated inhibition of senescence in pummelo fruit, the largest known citrus variety, remain unclear. Herein, postharvest 0.3% SA treatment was demonstrated to delay postharvest 'Jinshayou' pummelo senescence, as evidenced by the inhibitions in firmness loss, electrolyte leakage increase, and color change. Using comparative transcriptomic data, a total of 4367, 3769, and 1659 DEGs were identified between CK0 and CK60, CK0 and SA60, and CK60 and SA60, respectively. Further GO analysis revealed that DEGs were mainly implicated in the processes of cell wall modification and phenylpropanoid pathway during fruit senescence. More importantly, postharvest exogenous 0.3% SA treatment was observed to inhibit CWDEs activities and their encoding gene expression, retain higher protopectin, cellulose, and hemicelluloses contents, as well as reduce WSP content, thus maintaining cell wall structure. These findings collectively indicated that postharvest SA treatment was a green and useful preservative for alleviating fruit senescence and prolonging the storage life of harvested 'Jiashayou' pummelo fruit. [ABSTRACT FROM AUTHOR]

A microwave pretreatment method was developed to preserve pectin, naringin, and limonin contents in pomelo flavedo to allow for longer storage times and subsequent extraction of pomelo essential oil. In terms of the essential oil, microwave pretreatment performed better than hydrodistillation with respect to extraction efficiency (1.88 ± 0.06% in 24 min versus 1.91 ± 0.08% in 240 min), oxygenation fraction (48.59 ± 1.32% versus 29.63 ± 1.02%), energy consumption (0.15 kW h versus 1.54 kW h), and environmental impact (123.20 g CO 2 versus 1232 g CO 2 ). Microwave-pretreated samples retained higher amounts of pectin, naringin, and limonin compared with non-pretreated samples. No obvious change in the degree of pectin esterification was observed. This study shows that the proposed process is a promising methodology for both preserving valuable compounds in pomelo flavedo during storage and acquiring essential oils. [ABSTRACT FROM AUTHOR]

Highlights: [•] China is rich in pummelo germplasm which were underutilised. [•] The flavonoids and antioxidant activities of peels and pulps in 29 Chinese local pummelos and three grapefruits were reported. [•] Some Chinese local pummelos and three grapefruits were rich in flavonoid and exhibited high antioxidant capacity. [•] Remarkable variation was observed in flavonoids contents and antioxidant capacity. [ABSTRACT FROM AUTHOR]

Highlights: [•] Citrus grandis has volatiles, flavonoids and polysaccharides hardly being extracted. [•] One-step CCE extraction of all bioactive substances with gradient elution. [•] Simple extraction and separation with minimum use of solvents and energy. [•] All substances had 98% extraction rates and 95% recovery rates after separation. [•] Can be used widely with greatly increased utilisation of natural resources. [ABSTRACT FROM AUTHOR]

Highlights: [•] We compared OA metabolism and mineral nutrient status between normal and granulated juice sacs. [•] Granulation decreased citrate and isocitrate levels, thus lowering juice sac acidity. [•] The reduction in citrate concentration might be caused by increased degradation. [•] Granulation increased the levels of mineral elements (i.e. P, Mg, S, Zn and Cu) in juice sacs. [ABSTRACT FROM AUTHOR]

[Display omitted] • IDE sensor for naringin quantification in Pomelo fruit to predict maturity. • Sensor exhibits excellent selectivity for naringin and sensitivity of 0.008 µA for 10 ppb naringin. • Sensor can effectively quantify naringin in µM concentration. • Pomelo harvesting at 180–220 DAFS result maximum bioactive compounds. • Sensor determined naringin content effectively in other citrus cultivars also. Maturity determination of pomelo fruits having health-benefiting attributes is an important issue to enhance the quality of harvesting. Here, an interdigitated electrode (IDE) based sensor is introduced to detect its maturity by determining the naringin content. The sensor was made by depositing amberlite IRA-400 as a sensing layer on IDE patterned PCB substrate at room temperature with hydrothermal and spin-coating techniques. The sensor exhibits excellent selectivity for naringin, high sensitivity of 0.008 µA for 10 ppb of naringin, and reusability up to 3–4 times for naringin quantification in maturity testing of fruits. The pomelo fruits start to mature when maximum values of current response and naringin content are found at 140 DAFS. The naringin content decreases as maturity progresses and maximum phytochemical attributes were obtained at 180–220 DAFS. The IDE sensor assures an appropriate period of plucking of pomelo fruits improving harvesting practices and trade of citrus fruits. [ABSTRACT FROM AUTHOR]

• Granulated juice sacs were highly heterogenous in pomelo fruit. • Pectin methylesterase activity and calcium content increased upon granulation. • The depolymerization of pectin was inhibited during pomelo granulation. • Calcium may induce gelation of juice sacs by formation of "egg-box" with pectin. • Remodelling of complex network of pectin might induce pomelo granulation process. Postharvest granulation is a severe physiological disorder in citrus fruit that may be related to pectin metabolism. This study was designed to analyze the changes in fruit quality and pectin metabolism of pomelo fruit during granulation from expansion, gelation to lignification. Fruit quality showed a decrease starting from the gelation stage. Contents of water-soluble pectin, chelate-soluble pectin, sodium carbonate-soluble pectin and calcium, and activity of pectin methylesterase increased, while polygalacturonase activity decreased upon granulation. Atomic force microscopy analysis showed that both length and width of those three types of pectin molecules increased during granulation, accompanied by the decrease of linear structure molecules of pectin and the increase of pectin polymers, and multi-branched pectin tending to form cross-linked structure. Complex network of pectin might be remodeled during granulation process that immobilized the free water in juice sacs and induced the gelation occurrence, further promoted the granulation process. [ABSTRACT FROM AUTHOR]

Abstract: Pomelo (Citrus grandis L. Osbeck) is a native fruit of great economic importance in Southeast Asia. To provide experimental evidence for the antioxidant and antihyperlipidemic properties of pomelo, 6 cultivars, including Kao-Yai (KY), Thong-dee (TD), Kao-Tangkwa (KT), Kao-Numpueng (KN), Ta-Koi (TK), and Tubtim Siam (TS) were evaluated. KY had the highest phenolic content, and the strongest 1,1-diphenyl-2-pireyhydrazyl radical scavenging capacity and hydroxyl radical scavenging activity. From the high-performance liquid chromatography analysis, naringin and naringenin were the major flavonoids in the KT and TK cultivars. Six pomelo cultivars had antihyperlipidemic activities including the inhibition of pancreatic lipase and cholesterol esterase, as well as cholesterol micelle formation and bile acid binding. Hierarchical clustering analysis showed that the 6 cultivars were separated into 2 classifications. In addition, the total phenolics of the pomelo cultivars were significantly correlated with ferric reducing antioxidant power and Trolox equivalent antioxidant capacity. The results suggest that pomelo provides significant health benefits and may be used for developing functional foods. [Copyright &y& Elsevier]

Abstract: Epidemiological studies suggest that citrus fruits and compounds such as flavonoids, limonoids and pectins have health promoting effects. Our aim was to study the effects of Citrus grandis (L.) Osbeck var. tomentosa hort. fruit extract on the energy metabolism. A whole fruit powder from dry water and alcohol extracts of C. grandis containing 19% naringin flavonoid was prepared. The effects of the citrus extract were followed in the obese Zucker rats fed with the HFD. The circulatory levels of GLP-1 decreased significantly by the extract in comparison to the HFD group, whereas the decreased ghrelin levels were reversed. The levels of PYY were decreased in all HFD groups. The leptin amounts decreased but not significantly whereas insulin and amylin were unchanged. The cholesterol and glucose levels were somewhat but not systematically improved in the HFD fed rats. Further studies are needed to identify the active compounds and their mechanisms. [Copyright &y& Elsevier]

Abstract: The flavonoid composition of flavedos and juices from four Chinese pummelo cultivars (Citrus grandis ‘Shatianyu’, C. grandis ‘Guanximiyu’, C. grandis ‘Yuhuanyu’, and C. grandis ‘Cuixiangtianyu’) and one grapefruit cultivar (Citrus paradisi ‘Changshanhuyu’), was investigated using high-performance liquid chromatography diode array detection electrospray ionisation mass spectrometry (HPLC-DAD-ESI MS/MS). Twenty-eight flavonoids were identified. Naringin was the predominant flavanone in these pummelo varieties, whereas naringin and neohesperidin were the principal flavanones found in C. paradisi ‘Changshanhuyu’. The four pummelo cultivars had higher levels of flavones when compared with the grapefruit. Based on the flavonoid profiles in flavedos and juices, four pummelo cultivars and one grapefruit cultivar were well separated. [Copyright &y& Elsevier]

Abstract: The antioxidant potentials of buntan pumelo (Citrus grandis Osbeck) and its fermented products were determined. The essential oil from peel had higher total phenolic (214mM) and flavonoid (134mg QE/g of dried material) contents than those of different solvent extracts from fruit pulp. In addition, DPPH free radical-scavenging activity and ferric-reducing antioxidant power values determined for the essential oil were 26.1±1.2% and 2.3±0.3mM, respectively, which were significantly higher than those of various fruit pulp extracts. The ethanol-fermented products of pumelo juice had higher total phenolic and flavonoid contents than those of fresh juice. For maintenance of the substantial antioxidant properties of pumelo products, ethanol-fermented juice rather than fresh or acetate-fermented juice is recommended. Through correlation analysis, the phenolic compounds in the fermented pumelo products were found to be the major contributors to the free radical-scavenging activity and ferric-reducing power. [Copyright &y& Elsevier]

Abstract: The antiproliferative effect of an immature Citrus grandis Osbeck fruit extract was investigated using U937 human leukaemia cells. Maximum cytotoxicity was observed using the hexane fraction (HF) of the extract. Cell death was dose-dependent (IC 50 =ca. 60μg/ml) and was characterised by chromatin condensation, apoptotic body formation, and DNA fragmentation. The induction of apoptosis was confirmed by caspase-3 activity assays and by immunoblotting using antibodies against Bcl-2, Bax, poly(ADP-ribose) polymerase (PARP), caspase-9, and caspase-3. The molecular mechanism underlying HF-induced apoptosis in U937 cells may involve a mitochondria-mediated signalling pathway, as demonstrated by an increase in the Bax/Bcl-2 expression ratio. Analyses of the HF by gas chromatography (GC) and GC-mass spectrometry (MS) tentatively identified 19 compounds, including γ-sitosterol (17.5%), 7-methoxy-8-(2-oxo-3-methylbutyl) coumarin (6.8%), stigmasterol (3.8%), and campesterol (3.4%). Together, our results provide the first evidence that the HF of an immature C. grandis Osbeck fruit extract induces apoptosis in U937 cells. [Copyright &y& Elsevier]

• Amino-containing MOFs MIL-125-NH 2 was designed as a new sorbent in d-SPE. • MIL-125-NH 2 enrich the target analytes directly to improve sensitivity. • Amino-containing MIL-125-NH 2 has good adsorption capacity. • The detection limits were lower than most of traditional methods. • MIL-125-NH 2 is recovered easily and reused at least 8 times. A simple, environmentally-friendly and reliable method was developed to simultaneously monitor the residue of methyl 1-naphthalene acetate, parathion-methyl, fenitrothion, bromophos and phenthoate in pomelo by using dispersive solid-phase extraction technique (d-SPE). In this method, these target analytes were captured by MIL-125-NH 2 and detected by GC–MS/MS. The key parameters of d-SPE were optimized by the single factor experiment. Under the optimized conditions, a good determination coefficient (R2 > 0.9922) and extraction recoveries (64.7–116.8%) are obtained. The limit of detections (0.03–1.07 ng/g) is lower than the MRLs in citrus fruits established by EU (10–15000 ng/g) and China (10–10000 ng/g). The precisions of intra-day and inter-day are 1.3–8.9% and 3.8–14.9%, respectively. In addition, the sorbent MIL-125-NH 2 is stable and can be reused at least eight times. These results prove the established method is efficient and reliable to detect the pesticide residues in pomelo. [ABSTRACT FROM AUTHOR]

[Display omitted] • Four new flavonoid compounds were isolated from Citrus grandis Shatianyu pulp. • A HMG and a 4′-glucose substitution decreased the ORAC activity of flavonoids. • Melitidin, bergamjuicin and naringin contributed most to ORAC value of SPFEs. • Bergamjuicin, melitidin and cigranoside E contributed most to CAA value of SPFEs. The Citrus genus is a good source of dietary flavonoids, which have many health benefits. As a representative citrus fruit, the flavonoids composition in Shatianyu (Citrus grandis L. Osbeck) pulp remains to be investigated. In the present study, 11 flavonoids were isolated and identified from Shatianyu pulp flavonoid extracts (SPFEs). Among them, 4 flavonoids were previously undescribed and 2 flavonoids were firstly isolated from pummelo. The cellular antioxidant activity (CAA) and oxygen radical absorbance capacity (ORAC) of isolated compounds were evaluated. Naringin and rhoifolin showed the highest ORAC activity, and the presence of a 3-hydroxy-3-methylglutaryl or a 4′-glucose decreased the ORAC activity of flavonoids. The contribution of isolated flavonoids to the holistic antioxidant activity of SPFEs was determined by an online knockout method. Melitidin, bergamjuicin and naringin contributed most to ORAC activity, while bergamjuicin, melitidin and apigenin-4′- O - β - d -glucopyranosyl-7- O - α - l -rhamnopyranosyl-(1 → 2)-[6″- O -(3- hydroxy-3-methylgltaryl)]- β - d -glucopyranoside contributed most to CAA activity. [ABSTRACT FROM AUTHOR]

An enzyme that catalyses the transfer of a glucose unit from UDPG to limonoids was isolated from the albedo tissue of pummelo fruit (Citrus grandis Osbeck) in electrophoretically homogeneous form. The enzyme was purified to 180-fold by a combination of (NH4)2SO4 fractionation, ion exchange chromatography on DEAE-cellulose and DEAE-Toyopearl. SDS-PAGE showed a molecular weight of 55 kDa for the enzyme. The purified enzyme, limonoid glucosyltransferase, displayed an optimum activity at pH 7.8 and 37 °C with apparent Km values of 65 and 200 μM for limonin and UDPG, respectively. Mn2+ and Co2+ stimulated the enzyme activity by 33 and 30%, respectively, while EDTA completely inhibited it. Cu2+, Hg2+ and diethyl pyrocarbonate also inhibited the enzyme, indicating a possible role of histidine in catalysis. The enzyme was stable at 4 °C for 6 months in Tris–HCl buffer, pH 7.5. [Copyright &y& Elsevier]

• This is the first ELISA for naringenin using monoclonal antibodies. • Hapten of naringenin has been successfully prepared. • The developed icELISA offers an advantage for detecting naringenin in herb samples. Naringenin, a flavonoid compound found in pummelo, is a key biological active compound in some traditional Chinese medicines, including Citri reticulatae pericarpium , Citri reticulatae pericarpium viride , Aurantii fructus immaturus , and Aurantii fructus. These Chinese medicinal preparations are the peels or immature fruits of certain citrus species. Aiming at detecting naringenin in complex matrices such as pummelo and traditional Chinese medicines, we put forward a sensitive and practical indirect competitive enzyme-linked immunosorbent assay (icELISA) based on anti-naringenin monoclonal antibodies (anti-Nar-mAbs). The median inhibitory concentration (IC 50) was 4.43 ng/mL, and the working range was 1.15–15.81 ng/mL. The findings of the icELISA for the analysis of naringenin in pummelo and herb samples had a good correlation with the ultra performance liquid chromatography (UPLC) methodology and showed good accuracy and reproducibility. These data demonstrated that the developed icELISA is reliable, accurate, and suitable for detecting naringenin in pummelo and traditional Chinese medicines. [ABSTRACT FROM AUTHOR]

• Chitosan coating decreased granulation index, weight loss, firmness and membrane permeability in pummelo fruit. • Chitosan treatment maintained higher ATP content and energy metabolism-related enzymes activities. • Chitosan treatment mitigated postharvest senescence of pummelo through reducing energy depletion and maintaining TCA cycle. The effect of chitosan coating exposure on juice sac granulation and energy metabolism in harvested pummelo fruit was investigated. Pummelo fruits were exposed to 1.5% chitosan coating, and then stored at 20 ± 2 °C for about 150 days. Postharvest chitosan coating treatment apparently alleviated the development of juice sac granulation as well as the increases in weight loss, pulp firmness, cell membrane permeability and cellulose content. The levels of adenosine triphosphate (ATP), adenosine diphosphate (ADP) and energy charge (EC) in the chitosan-coated fruit showed significantly higher levels than those of the respective controls. Meanwhile, the enzymses actively engaged in energy metabolism such as H+-ATPase, Ca2+-ATPase, Mg2+-ATPase, cytochrome C oxidase (CCO), succinate dehydrogenase (SDH) and malate dehydrogenase (MDH) were markedly maintained by chitosan coating. Besides, notably high contents of acetyl-CoA, cis-aconitate, succinate, fumarate and oxaloacetate were observed in the chitosan-coated fruit. The results highlighted that chitosan coating could delay postharvest senescence of pummelo fruit by reducing the rate of energy depletion while maintaining higher levels of key metabolites taking part in tricarboxylic acid (TCA) cycle at room temperature storage. [ABSTRACT FROM AUTHOR]

• Xanthophylls esters are the main carotenoids in orange-pigmented citrus fruit. • Specific PYP/XES genes are ripening regulated in sweet orange and mandarin fruit. • Transcript levels of PYP1,2 and 6 are correlated with the carotenoid esters content in sweet orange. • Expression of PYP in yellow citrus is in accordance with low xanthophyll-esters level. • The PYP/XES are promising candidates for xanthophyll esterification in citrus. In orange-pigmented citrus fruits, the xanthophyll esters are the predominant carotenoids, but their biosynthetic origin is currently unknown. In this work, seven PYP/XES (Pale Yellow Petal/ Xanthophyll esterase) genes were identified in Citrus genomes, but only PYP1-4 and 6 contained the structural domains essential for activity. The PYP/XES expression profiles in sweet orange and in other Citrus species such as lemon, mandarin and pummelo with marked differences in fruit pigmentation and content of xanthophylls esters, showed the upregulation of PYP1,2 and 6 genes during ripening only in orange-pigmented fruits. Moreover, transcript levels of PYP1, 2 and 6 genes in peel and pulp of sweet orange were accompanied by the accumulation of xanthophyll esters during ripening. This work reports for the first time the PYP/XES gene family in C itrus and strongly suggests its involvement in xanthophyll esterification in citrus fruit tissues and its influence in carotenoid accumulation and fruit pigmentation. [ABSTRACT FROM AUTHOR]

• 1.5% chitosan coating suppressed juicy sac granulation of harvested pummelo through maintaining cell wall modification. • Chitosan reduced the deposition of lignin and cellulose in pummelo fruit. • Chitosan reduced the activities and down-regulated the expression levels of lignin synthesis-related enzyme. • Chitosan increased the activities and up-regulated the expression levels of cell wall degrading enzymes. Deposition of both lignin and cellulose accompanied by juice sac granulation is widespread in harvested citrus fruit. Hence, measures to suppress postharvest granulation of 'Majiayou' pummelo is of great importance. The fruit was treated with 1.5% chitosan and then stored at room temperature (20 ± 2 °C) for 150 d. As compared to the control fruits, chitosan coating significantly suppressed granulation index and maintained good quality. Chitosan coating inhibited lignification by suppressing the activities and expression levels of lignin synthesis-related enzymes (PAL, CAD and POD). By contrast, chitosan treatment enhanced the activities and expression levels of cell wall degrading enzymes, including PME, PG, Cx, XTH and β-Gal, which might contribute to the decrease in cellulose. In a nutshell, chitosan coating can effectively suppress juice sac granulation and fruit senescence of pummelo fruits, and play a crucial role in maintaining the cell wall modification. [ABSTRACT FROM AUTHOR]