The Potential of Plum Seed Residue: Unraveling the Effect of Processing on Phytochemical Composition and Bioactive Properties.

Bioactive compounds extracted from plum seeds were identified and quantified, aiming to establish how the brandy manufacturing process affects the properties and possible cascade valorization of seed residues. Extraction with n-hexane using Soxhlet has provided oils rich in unsaturated fatty acids (92.24-92.51%), mainly oleic acid (72-75.56%), which is characterized by its heart-healthy properties. The fat extracts also contain tocopherols with antioxidant and anti-inflammatory properties. All the ethanol-water extracts of the defatted seeds contain neochlorogenic acid (90-368 µg·g-1), chlorogenic acid (36.1-117 µg·g-1), and protocatechuate (31.8-100 µg·g-1) that have an impact on bioactive properties such as antimicrobial and antioxidant. Anti-amyloidogenic activity (25 mg·mL-1) was observed in the after both fermentation and distillation extract, which may be related to high levels of caffeic acid (64 ± 10 µg·g-1). The principal component analysis showed that all plum seed oils could have potential applications in the food industry as edible oils or in the cosmetic industry as an active ingredient in anti-aging and anti-stain cosmetics, among others. Furthermore, defatted seeds, after both fermentation and distillation, showed the greatest applicability in the food and nutraceutical industry as a food supplement or as an additive in the design of active packaging.

Proanthocyanidins in Pruning Wood Extracts of Four European Plum (Prunus domestica L.) Cultivars and Their hLDHA Inhibitory Activity.

European plum tree (Prunus domestica L.) is cultivated in many countries for its delicious and nutritive fruit and, accordingly, certain amounts of wood (from pruning works) are generated every year. The main objective of this work was to value this agricultural woody residue, for which the chemical composition of pruning wood extracts from four European plum cultivars was investigated, and the human lactate dehydrogenase A (hLDHA) inhibitory activity of plum wood extracts and pure proanthocyanidins present in those extracts was measured. For the chemical characterization, total phenolic content and DPPH radical-scavenging assays and HPLC-DAD/ESI-MS analyses were performed, the procyanidin (-)-ent-epicatechin-(2α→O→7,4α→8)-catechin (4), the phenolic glucoside (-)-annphenone (3) and the flavan-3-ol catechin (1) being the major components of the wood extracts. Some quantitative and qualitative differences were found among plum cultivars, and the content of proanthocyanidins ranged from 1.51 (cv. 'Claudia de Tolosa') to 8.51 (cv. 'De la Rosa') mg g-1 of dry wood. For the hLDHA inhibitory activity, six wood extracts and six proanthocyanidins were evaluated by a UV spectrophotometric assay, compound 4 showing the highest inhibitory activity (IC50 3.2 µM) of this enzyme involved on the excessive production of oxalate in the liver of patients affected by the rare disease Primary Hyperoxaluria.

Drying date plum (Diospyros lotus L.) fruit: Assessing rehydration properties, antioxidant activity, and phenolic compounds.

Date plum (Diospyrus lotus L.) is an edible fruit from the Ebenaceae family, rich in nutrients, and having tremendous medicinal properties. This paper attempted to show the influence of different parameters of convective drying such as temperature (50, 60, 70, and 80°C) and air velocity (0.5, 1.0, and 1.5 m/s) on the shrinkage and microstructure, rehydration properties, antioxidant activity, and phenolic compounds of date plum. The drying caused significant changes in the color, actual size, and distribution of the fruit cells of date plum. The total phenolic content (TPC), total flavonoid content (TFC), ferric reducing antioxidant power (FRAP), and 2,2-diphenyl-1-picrylhydrazyl (DPPH) of fresh date plum were 0.81 ± 0.00 mg GAE/g, 0.23 ± 0.10 mg ECE/g, 7.15 ± 1.09 mmol ISE/g, and 14.92 ± 0.88 mmol/TE, respectively. The drying at 70°C had the highest values of TPC, TFC, gallic acid, chlorogenic and syringic acids, catechin, quercetin-3-glucoside, resveratrol, and DPPH. The drying air velocities showed no significant effects on the antioxidant contents and the antioxidant activity. Of the models applied to the drying kinetics, the Midilli model was found as the best model to describe the drying kinetics of date plum. In addition, the Weibull model was found as the most successful among the models applied to the rehydration kinetics of date plum. According to the achieved findings, the convective drying temperature of 70°C is the optimum temperature to produce the dehydrated date plum. Practical Application This work has revealed the drying conditions responsible for preserving the phenolic compounds, total flavonoid content, and antioxidant features of D. lotus L. The study found the optimum drying conditions, and Midilli and Weibull models were the most fitted models to describe the drying and rehydration behaviors of D. lotus L. fruits, respectively. The drying provides a reasonable value of the possibility of continuous consumption of the fruits dried afforded on off-seasons. The dried fruits are widely used for multipurpose and have been extensively used in food industries due to their rich nutraceutical and antioxidant compounds.

Hydroethanolic Extract of Prunus domestica L.: Metabolite Profiling and In Vitro Modulation of Molecular Mechanisms Associated to Cardiometabolic Diseases.

High consumption of fruit and vegetables has an inverse association with cardiometabolic risk factors. This study aimed to chemically characterize the hydroethanolic extract of P. domestica subsp. syriaca fruit pulp and evaluate its inhibitory activity against metabolic enzymes and production of proinflammatory mediators. Ultra-high-performance liquid chromatography high-resolution mass spectrometry(UHPLC-HRMS) analysis showed the presence of hydroxycinnamic acids, flavanols, and glycoside flavonols, while nuclear magnetic resonance(NMR) analysis showed, among saccharides, an abundant presence of glucose. P. domestica fruit extract inhibited α-amylase, α-glucosidase, pancreatic lipase, and HMG CoA reductase enzyme activities, with IC50 values of 7.01 mg/mL, 6.4 mg/mL, 6.0 mg/mL, and 2.5 mg/mL, respectively. P. domestica fruit extract inhibited lipopolysaccharide-induced production of nitrite, interleukin-1 ß and PGE2 in activated J774 macrophages. The findings of the present study indicate that P. domestica fruit extracts positively modulate in vitro a series of molecular mechanisms involved in the pathophysiology of cardiometabolic diseases. Further research is necessary to better characterize these properties and their potential application for human health.

Co-Ingestion of Natal Plums (Carissa macrocarpa) and Marula Nuts (Sclerocarya birrea) in a Snack Bar and Its Effect on Phenolic Compounds and Bioactivities.

This study investigated the effect of co-ingesting Natal plums (Carissa macrocarpa) and Marula nuts (Sclerocarya birrea) on the bioaccessibility and uptake of anthocyanins, antioxidant capacity, and the ability to inhibit α-glucosidase. A Natal plum-Marula nut bar was made by mixing the raw nuts and the fruit pulp in a ratio 1:1 (v/v). The cyanidin-3-O-sambubioside (Cy-3-Sa) and cyanidin-3-O-glucoside content (Cy-3-G) were quantified using the ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC/Q-TOF-MS). Inclusion of Natal plum in the Marula nut bar increased the Cy-3-Sa, Cy-3-G content, antioxidants capacity and α-glucosidase inhibition compared to ingesting Marula nut separately at the internal phase. Adding Natal plum to the Marula nut bar increased bioaccessibility of Cy-3-Sa, Cy-3-G, quercetin, coumaric acid, syringic acid and ferulic acid to 80.2% and 71.9%, 98.7%, 95.2%, 51.9% and 89.3%, respectively, compared to ingesting the Natal plum fruit or nut separately.

Polyphenolic QTOF-ESI MS Characterization and the Antioxidant and Cytotoxic Activities of Prunus domestica Commercial Cultivars from Costa Rica.

There is an increased interest in plum research because of their metabolites' potential bioactivities. In this study, the phenolic profiles of Prunus domestica commercial cultivars (Methley, Pisardii and Satsuma) in Costa Rica were determined by Ultra Performance Liquid Chromatography coupled with High Resolution Mass Spectrometry using a quadrupole-time-of-flight analyzer (UPLC-ESI-QTOF MS) on enriched phenolic extracts obtained through Pressurized Liquid Extraction (PLE) under acidic and neutral extraction conditions. In total, 41 different phenolic compounds were identified in the skin and flesh extracts, comprising 11 flavan-3-ols, 14 flavonoids and 16 hydroxycinnamic acids and derivatives. Neutral extractions for the skins and flesh from all of the cultivars yielded a larger number of compounds, and were particularly rich in the number of procyanidin trimers and tetramers when compared to the acid extractions. The total phenolic content (TPC) and antioxidant potential using the DPPH and ORAC methods exhibited better results for neutral extracts with Satsuma skins and Methley flesh, which showed the best values (685.0 and 801.6 mg GAE/g extract; IC50 = 4.85 and 4.39 µg/mL; and 12.55 and 12.22 mmol TE/g extract, respectively). A Two-Way ANOVA for cytotoxicity towards AGS gastric adenocarcinoma and SW620 colon adenocarcinoma indicated a significant difference (p < 0.05) for PLE conditions, with better results for neutral extractions, with Satsuma skin delivering the best results (IC50 = 60.7 and 46.7 µg/mL respectively) along with Methley flesh (IC50 = 76.3 and 60.9 µg/mL, respectively). In addition, a significant positive correlation was found between TPC and ORAC (r = 0.929, p < 0.05), as well as a significant negative correlation (p < 0.05) between TPC and cytotoxicity towards AGS and SW620 cell lines (r = -0.776, and -0.751, respectively). A particularly high, significant, negative correlation (p < 0.05) was found between the number of procyanidins and cytotoxicity against the AGS (r = -0.868) and SW620 (r = -0.855) cell lines. Finally, the PCA clearly corroborated that neutral extracts are a more homogenous group exhibiting higher antioxidant and cytotoxic results regardless of the part or cultivar; therefore, our findings suggest that PLE extracts under neutral conditions would be of interest for further studies on their potential health benefits.

Biobased Polyurethane Composite Foams Reinforced with Plum Stones and Silanized Plum Stones.

In the following study, ground plum stones and silanized ground plum stones were used as natural fillers for novel polyurethane (PUR) composite foams. The impact of 1, 2, and 5 wt.% of fillers on the cellular structure, foaming parameters, and mechanical, thermomechanical, and thermal properties of produced foams were assessed. The results showed that the silanization process leads to acquiring fillers with a smoother surface compared to unmodified filler. The results also showed that the morphology of the obtained materials is affected by the type and content of filler. Moreover, the modified PUR foams showed improved properties. For example, compared with the reference foam (PUR_REF), the foam with the addition of 1 wt.% of unmodified plum filler showed better mechanical properties, such as higher compressive strength (~8% improvement) and better flexural strength (~6% improvement). The addition of silanized plum filler improved the thermal stability and hydrophobic character of PUR foams. This work shows the relationship between the mechanical, thermal, and application properties of the obtained PUR composites depending on the modification of the filler used during synthesis.

Elucidation of glycosylation sites of kaempferol di-O-glycosides from methanolic extract of the leaves of Prunus domestica subsp. syriaca.

RATIONALE: Flavonol glycosides containing the glycosylation patterns 3,4'-di-O and 4',7-di-O are rare in nature and they have not yet been studied in detail by electrospray ionization mass spectrometry (ESI-MS(+/-), in contrast to the flavonol glycosides containing the glycosylation pattern 3,7-di-O. METHOD: The leaves from Prunus domestica L. subsp. syriaca were extracted with pure methanol or, in order to perform hydrolysis and extraction simultaneously, with a 5% methanolic solution of hydrochloric acid. The high-performance liquid chromatography (HPLC)/ESI-MS(+/-) analyses were performed using a Waters model 2690 HPLC pump and a Waters/Micromass ZQ2000 mass spectrometer. RESULTS: Three kinds of kaempferol di-O-glycosides have been identified, namely kaempferol-3-O-hexoside-7-O-rhamnosides, kaempferol-3-O-pentoside-4'-O-rhamnosides and kaempferol 4',7-di-O-rhamnoside. The identification was performed on the basis of the abundances of the respective Y-type product ions. CONCLUSIONS: The abundances of [Yn 0 - H]-· , Yn 0 - and Yn 0 + product ions were of crucial importance for the determination of glycosylation patterns. The obtained results can be useful for HPLC/ESI-MS identification of rare flavonol-di-O-glycosides.

Research on the Prediction of Green Plum Acidity Based on Improved XGBoost.

The acidity of green plum has an important influence on the fruit's deep processing. Traditional physical and chemical analysis methods for green plum acidity detection are destructive, time-consuming, and unable to achieve online detection. In response, a rapid and non-destructive detection method based on hyperspectral imaging technology was studied in this paper. Research on prediction performance comparisons between supervised learning methods and unsupervised learning methods is currently popular. To further improve the accuracy of component prediction, a new hyperspectral imaging system was developed, and the kernel principle component analysis-linear discriminant analysis-extreme gradient boosting algorithm (KPCA-LDA-XGB) model was proposed to predict the acidity of green plum. The KPCA-LDA-XGB model is a supervised learning model combined with the extreme gradient boosting algorithm (XGBoost), kernel principal component analysis (KPCA), and linear discriminant analysis (LDA). The experimental results proved that the KPCA-LDA-XGB model offers good acidity predictions for green plum, with a correlation coefficient (R) of 0.829 and a root mean squared error (RMSE) of 0.107 for the prediction set. Compared with the basic XGBoost model, the KPCA-LDA-XGB model showed a 79.4% increase in R and a 31.2% decrease in RMSE. The use of linear, radial basis function (RBF), and polynomial (Poly) kernel functions were also compared and analyzed in this paper to further optimize the KPCA-LDA-XGB model.

Extraction process and composition identification of anthocyanins from xinjiang wild Prunus cerasifera fruit peel.

To extract anthocyanins from wild Prunus cerasifera fruit peel and to identify the main compositions. The effects of extraction solvent, solid-to-liquid ratio, extraction time and extraction temperature on the extraction rate of anthocyanins were determined using colorimetric method, differential spectrophotometry and L9 (34) orthogonal experiment. The structure of the anthocyanins extracted from wild Prunus cerasifera fruit peel was preliminarily identified by liquid chromatography-electrospray ionization-tandem mass spectrometry. And hydroxyl radical scavenging rate and DPPH radical scavenging rate were used to investigate the antioxidant activity of Xinjiang cherry anthocyanin in vitro. The highest extraction rate of anthocyanins was acquired under the conditions including 1% HCl-methanol, solid-to-liquid ratio =1:5, extraction temperature 55°C and extraction time 80 minutes. Liquid chromatography-electrospray ionization-tandem mass spectrometry results showed that the main compositions of anthocyanins were cyanidin 3-galactoside, cyanidin 3-glucoside, cyanidin 3-rutinoside and cyanidin 3-xyloside. The results of antioxidant test showed that Xinjiang cherry anthocyanin had certain scavenging effect on 1, 1-diphenyl-2-picrylphenylhydrazine (DPPH•) and hydroxyl radical (•OH), but was weaker than Vc. Findings from this study provide evidence for extraction process and composition identification of anthocyanins from Xinjiang wild Prunus cerasifera fruit peel.

Anthocyanins attenuate vascular and inflammatory responses to a high fat high energy meal challenge in overweight older adults: A cross-over, randomized, double-blind clinical trial.

BACKGROUND & AIMS: Postprandial metabolic imbalances are important indicators of later developing cardiovascular disease (CVD). This study investigated the effects of food anthocyanins on vascular and microvascular function, and CVD associated biomarkers following a high fat high energy (HFHE) meal challenge in overweight older adults. METHODS: Sixteen subjects (13 female, 3 male, mean age 65.9 SD 6.0 and body mass index 30.6 kg/m2 SD 3.9) participated in a crossover, randomized, controlled, double-blind clinical trial (registered under Australian New Zealand Clinical Trials Registry, identifier no. ACTRN12620000437965). Participants consumed a HFHE meal with a 250 mL dose of either intervention (anthocyanins-rich Queen Garnet Plum) or control (apricot) juice. Blood samples and blood pressure measures were collected at baseline, 2 h and 4 h following the HFHE meal. Vascular and microvascular function were evaluated at baseline and 2 h after the HFHE meal. RESULTS: Participants had a higher 2 h postprandial flow-mediated dilatation (+1.14%) and a higher microvascular post-occlusive reactive hyperaemia (+0.10 perfusion units per mmHg) when allocated to the anthocyanin compared to the control arm (P = 0.019 and P = 0.049, respectively). C-reactive protein was lower 4 h postprandially in the anthocyanins (1.80 mg/L, IQR 0.90) vs control arm (2.30 mg/L, IQR 1.95) (P = 0.026), accompanied by a trend for lower concentrations of interleukin-6 (P = 0.075). No significant postprandial differences were observed between treatments for blood pressure, triacylglycerol, total cholesterol, serum derivatives of reactive oxidative metabolites, tumor necrosis factor alpha, interleukin-1 beta, or maximum microvascular perfusion following iontophoresis of acetylcholine. CONCLUSION: Fruit-based anthocyanins attenuated the potential postprandial detrimental effects of a HFHE challenge on parameters of vascular and microvascular function, and inflammatory biomarkers in overweight older adults. Anthocyanins may reduce cardiovascular risk associated with endothelial dysfunction and inflammatory responses to a typical high fat 'Western' meal. Further studies are required to better elucidate the clinical implications of postprandial biomarkers of CVD.

Application of visible/NIR spectroscopy for the estimation of soluble solids, dry matter and flesh firmness in stone fruits.

BACKGROUND: Soluble solids concentration (SSC), dry matter concentration (DMC) and flesh firmness (FF) are important fruit quality parameters in stone fruits. This study investigated the ability of a commercial visible/near-infrared (NIR) spectrometer to determine SSC, DMC and FF in nectarine, peach, apricot and Japanese plum cultivars at harvest. The work was conducted in summer 2019/2020 on 14 stone fruit cultivars at Tatura, Australia. Two sub-samples of 100 fruit each were collected before and after commercial maturity (± 5 days) in order to maximize sample variability. RESULTS: Partial least square (PLS) regression models based on the second derivative of the absorbance in the 729-975 nm spectral region proved accurate for the prediction of SSC and DMC (R2 CV > 0.750). Only the model generated for SSC in 'Golden May' apricot was less precise compared to other cultivars. No visible/NIR models were accurate enough to predict FF in the cultivars under study (R2 CV < 0.750). CONCLUSION: This study demonstrated that the visible/NIR spectrometer was a reliable tool to monitor SSC and DMC in stone fruits at harvest but proved less useful for FF estimation. These results highlight the potential of visible/NIR spectrometry to evaluate stone fruit quality both in situ pre-harvest and in the laboratory after harvest. © 2020 Society of Chemical Industry.

Effect of thermosonication on quality attributes of hog plum (Spondias mombin L.) juice.

The use of thermosonication (TS) technique to preserve the qualities of fruit juice as an alternative to conventional pasteurization has attracted research interest in recent times. In the present study, freshly prepared hog plum juice (control), and the juice samples subjected to pasteurization (90 °C for 60 s) and thermosonication (40 kHz, 400 W at 40, 50 and 60 °C each for 5, 10, 20 and 30 min) were each analyzed for physicochemical, bioactive, microbial and sensory properties. After treatment, no significant changes in pH, total soluble solids and titratable acidity were observed. Notably, TS at 40 and 50 °C significantly (p < 0.05) improved color parameters, cloudiness and browning index. Furthermore, thermosonication increased ascorbic acid (11.40-18.55%), total phenolic content (17.98-18.35%), carotenoids (2.19-4.30%), flavonoids (10-16%) and antioxidant activity (32.52-48.5%) relative to the control. Both treatments significantly reduced the microbial count to non-detectable level after processing, while sensory attributes slightly improved. However, TS treatment at 60 °C decreased most of the quality parameters. Results showed that TS can improve quality, safety and economic potential of hog plum juice as a feasible alternative to pasteurization.

A novel herbal immunostimulant for rainbow trout (Oncorhynchus mykiss) against Yersinia ruckeri.

In this 21-day study, we examined the effects of the aqueous methanolic extract of thin-skinned plum (Prunus domestica) on growth, immune response and resistance to a pathogenic bacterium, Yersinia ruckeri in rainbow trout (Oncorhynchus mykiss). Fish were fed with diets containing thin-skinned plum extract doses as 0 (Control) 0.1 (PD01), 0.5 (PD05) and 1% (PD1) ad libitum twice in a day. At the end of the study, growth was affected positively but not significantly. Feed conversion ratio (FCR) was decreased in the PD01 group (P < 0.05). There were elevated respiratory burst and potential bacterial killing activities on the 7th day in the PD1 fish group. No differences were observed in lysozyme activity (P > 0.05). An increased myeloperoxidase activity was recorded on the 14th day of study. Expression of interleukin and COX-2 genes was elevated on the 7th day of study in the kidney and intestine of treated fish. Histological results indicated no marked changes in organs (gill, kidney, liver and spleen) of PD treated fish groups. Challenge results of fish in all plum extract-treated groups showed an increased survival rate against Y. ruckeri (P < 0.05). This study indicated that the thin-skinned plum aqueous methanolic extract could improve innate immunity, survival against Y. ruckeri and decrease the FCR level.

Effect of benzothiadiazole treatment on quality and anthocyanin biosynthesis in plum fruit during storage at ambient temperature.

BACKGROUND: Plums tend to experience a reduction in fruit quality due to ripening and they deteriorate quickly during storage at room temperature. Benzothiadiazole (BTH) is a plant elicitor capable of inducing disease resistance in many crops. In this study, the effect of BTH treatment on fruit ripening, fruit quality, and anthocyanin biosynthesis in 'Taoxingli' plum was investigated. RESULTS: The results showed that BTH treatment could accelerate fruit ripening without affecting the incidence of fruit decay or the shelf life. Benzothiadiazole treatment improved the quality and consumer acceptability of 'Taoxingli' plums during storage by increasing the sweetness, red color formation, and the concentration of healthy antioxidant compounds. The BTH treatment could also effectively promote the biosynthesis of anthocyanin by enhancing the enzyme activities of phenylalanine ammonia-lyase (PAL), dihydroflavonol 4-reductase (DFR), anthocyanidin synthase (ANS), and uridine diphosphate flavonoid 3-O-glucosyltransferase (UFGT) and up-regulating the gene expressions of PsPAL, PsCHI, PsDFR, PsANS, and PsUFGT during storage. CONCLUSION: Benzothiadiazole treatment could be a potential postharvest technology for improving fruit quality and consumer acceptability in harvested plum fruit. © 2020 Society of Chemical Industry.

Pinoresinol-4-O-ß-D-glucopyranoside: a lignan from prunes (Prunus domestica) attenuates oxidative stress, hyperglycaemia and hepatic toxicity in vitro and in vivo.

OBJECTIVES: This study aimed to explore the pharmacological properties of pinoresinol-4-O-ß-D-glucopyranoside (PG), isolated from prunes. METHODS: In-vitro antioxidant activity was assessed using ferric reducing antioxidant power (FRAP) and 2,2'-azino-bis [3-ethylbenzothiazoline-6-sulfonic acid]-diammonium salt (ABTS) assays. In-vivo hepatoprotective activity was evaluated using CCl4 -induced hepatotoxicity mouse model. The antihyperglycaemic activity was determined in vitro using α-glucosidase and α-amylase inhibiting activity and in vivo using streptozotocin-treated model. Molecular modelling was done on α-amylase, α-glucosidase, aldose reductase and peroxisome proliferator-activated receptor gamma. KEY FINDINGS: Pinoresinol-4-O-ß-D-glucopyranoside showed promising antioxidant activity in FRAP and ABTS assays with total antioxidant capacity equal 418.47 and 1091.3 µmol/g in terms of ascorbic acid, respectively. PG (50 mg/kg b.w.) exhibited a hepatoprotective activity in vivo as it lowered AST and ALT levels. PG showed a potent in-vitro antihyperglycaemic activity as it inhibited α-glucosidase with an IC50 value of 48.13 µg/ml. PG caused a prominent decline in serum glucose level by 37.83% in streptozotocin-treated mice with promising elevation in insulin level of 25.37%. Oxidative stress markers were reduced by PG, and it showed a high fitting on α-amylase and α-glucosidase active sites. CONCLUSIONS: Pinoresinol-4-O-ß-D-glucopyranoside is a natural entity combating oxidative stress, hepatic damage and diabetes.

Pectin-based edible coating preserves antioxidative capacity of plum fruit during shelf life.

Exploiting safer methods for fruit preservation such as application of edible coatings can improve shelf life, valuable characteristics, and antioxidative capacity. The current study aimed to investigate the effect of a pectin-based edible coating on antioxidative capacity of plum fruit during shelf life (19 ± 2 ℃ and 65% relative humidity for eight days). To do this, three solutions (0.5, 1, and 1.5%) of pectin, plasticized by glycerol (0.3% w/v), were applied on plum fruit and compared to a control treated with only distilled water. Ascorbic acid, total phenolics, anthocyanin and flavonoid contents, total antioxidative capacity based on 1,1-diphenyl-2-picryl-hydrazyl hydrate method, peroxidase (as an antioxidant enzyme), and polyphenol oxidase (as an oxidant enzyme) activities were recorded during this period. The results demonstrated that pectin-based edible coating was significantly effective on maintaining ascorbic acid, anthocyanin and flavonoid contents, and antioxidative capacity in plum fruits (P ≤ 0.01). The activities of enzymes were significantly affected by the coatings; peroxidase activity increased and polyphenol oxidase activity decreased (P ≤ 0.01). All pectin concentrations significantly caused higher ascorbic acid and anthocyanin contents, antioxidative capacity, and peroxidase activity but a lower polyphenol oxidase activity than the control; however, just 1 and 1.5% concentrations were effective in terms of total phenolic compounds and flavonoid content, respectively, and the other concentrations acted the same as the control. In general, the coating constituted from 1.5% pectin showed the best results for most measured parameters. Considering the influences of pectin-based edible coating on antioxidative characteristics of plum fruits, its application can be potentially regarded as a favorable method to enhance nutritional value of fruits.

Identification of Somatosensory Compounds Contributing to Slipperiness and Thickness Perceptions in Canned Prunes (Prunus domestica).

The role of small molecules on the somatosensory properties of prunes (Prunus domestica) was investigated. Sensory descriptive analysis defined two main somatosensations, "thickness" and "slippery". On the basis of these two attributes, sensory-guided multidimensional fractionation techniques allowed for the isolation of four main compounds, which were identified by mass spectrometry and comparison to authentic standards. Three compounds were identified as monosubstituted isomers of chlorogenic acid, namely, 1-O-caffeoylquinic acid (1-CQA), 3-O-caffeoylquinic acid (3-CQA), and 4-O-caffeoylquinic acid (4-CQA), in addition to a fourth, vanillic acid glucoside (VG). Sensory recombination model analysis of each compound at endogenous concentrations of the prunes indicated that all compounds significantly contributed to slippery sensations, whereas 3-CQA, 4-CQA, and VG contributed to thickness sensations (α = 0.05).

Physico-Chemical Properties and Oxidative Stability of Fixed Oil from Plum Seeds (Prunus domestica Linn.).

Storage of a great amount of plum kernel waste becomes a challenge for food industry. In this work, the plum seed was used as a source of fixed oil that can be an ingredient of commercial products. Soxhlet extraction was carried out using the different solvents, such as n-hexane, n-heptane, ethyl acetate, acetone, or chloroform:methanol mixture (2:1 v/v). The highest yield of oil (about 30%) was obtained using n-heptane and n-hexane, while the lowest yield was obtained using ethyl acetate. The analysis of physico-chemical parameters indicated that all samples of plum seed oil have an exceptional quality. Schaal oven test indicated that the fixed oil of plum seed exhibited satisfactory oxidative stability at moderate storage temperatures (up to 65 °C). The composition of phenolic compounds in the oil samples was determined using HPLC method. The most abundant compound of seven identified and quantified phenolic compounds was vanillic acid. The highest content of ß-carotene (1.67 mg 100 g-1 fixed oil) spectrophotometrically determined was in the oil extracted with n-hexane. The lowest content of ß-carotene (1.26 mg 100 g-1 fixed oil) was determined in the oil extracted with a mixture of chloroform:methanol (2:1 v/v). This oil had the highest antioxidant activity (IC50 value of 4.35 mg mL-1) compared to other oil samples. The antioxidant activity was probably caused by the presence of phenolic compounds. The investigated physico-chemical properties demonstrated that the plum seed oil has a potential for application in the food, cosmetics, and pharmaceutical industry.

Histochemical Analysis of Anthocyanins, Carotenoids, and Flavan-3-ols/Proanthocyanidins in Prunus domestica L. Fruits during Ripening.

As a result of the high variability of fruit properties in the European plum Prunus domestica, a histochemical analysis of fruits at different stages of development was performed to understand the ripening process in cv. 'Colora' (yellow-red skinned) and cv. 'Topfive' (purple skinned). Histological analysis showed that carotenoids in the fruit had two different origins. In the fruit flesh, they derived from chloroplasts that turned into chromoplasts, whereas carotenoids in the fruit skin derived probably from proplastids. Flavan-3-ols and proanthocyanidins showed differential localization during ripening. They were visible in the vacuole in different fruit tissues or organized in tannosomes in the fruit flesh. Tanninoplasts were observed only in hypodermal cells of 'Colora'. Toward maturity, anthocyanins were detected in the epidermis and later in the hypodermis of both cultivars. The study forms a basis for the analysis of the biosynthesis of secondary metabolites in European plums and their biological effects.