Anthocyanin and organic acid profiles of pomegranate (Punica granatum L.) juices from registered varieties in Turkey

This is the first study to analyse the profiles of anthocyanin (ACN) and organic acid (OA) and some physico‐chemical properties of pomegranate juices (PJs) obtained from nine registered varieties in Turkey. HPLC analyses revealed that there were significant differences between ACN contents (28–447 mg L^?1) and profiles (P < 0.01). The PJs contain maximum six ACNs, 3‐glucosides and 3,5‐diglucoside of delphinidin, cyanidin and pelargonidin. The major OA in PJs was citric acid (66–74%), followed by malic (6–12%), succinic (5–19%), nonidentified (0–14%) and tartaric acids (0.1–3.7%). Amongst individual OAs, citric acid had the most significant effects on TA (r = 0.9761), pH (r = 0.9208) values and sourness of PJs. As different from literature, results of this study revealed that malic acid contents of authentic PJs could be higher than 1.5 g L^?1. Consequently, ACN and OA profiles could be successfully used in quality control because all PJs have their own typical ACN and OA profiles.     

Polyphenol and volatile profiles of pomegranate (Punica granatum L.) fruit extracts and liquors

This work reports on the preparation of new aromatic pomegranate liquors by maceration of pomegranate juice and arils in Arbutus unedo L. distillate. The volatile, anthocyanin and ellagitannin profiles were monitored after each step. Aromatic compounds of pomegranates, such as limonene, 1‐hexenol and trans‐caryophyllene, were detected in trace levels and showed little contribution to the liquor aroma. The main volatiles of the liquors, namely isobutanol, isopentanols, vitispiranes and volatile esters, are given by the fruit distillate. The anthocyanin contents of the pomegranate juice were around 135 mg L^?1 but decreased to about 5% of this value in the final liquors. Anthocyanin diglucoside compounds showed higher stability than their monoglucoside analogs. Punicalagins and punicalins showed contents between 80 and 135 mg L^?1, depending on the used starting pomegranate material. These ellagitannins account for 60% of the total polyphenols. The procedure can be used to prepare aromatic pomegranate liquors with high polyphenol content.     

Influence of origin source, different fruit tissue and juice extraction methods on anthocyanin, phenolic acid, hydrolysable tannin and isolariciresinol contents of pomegranate (Punica granatum L.) fruits and juices

To gain more comprehensive knowledge of pomegranate (Punica granatum L.) fruit composition and its impact on juice features, fruits and juices produced from fruits of eleven different provenances were investigated by HPLC–DAD-ESI/MSⁿ for their monomeric phenolic and lignan profiles. Total phenolics and antioxidant capacity were monitored by the Folin-Ciocalteu, ferric reducing antioxidative power and Trolox equivalent antioxidant capacity assays. Peels, mesocarp, seeds and juices obtained from isolated arils (PJAs) as well as from entire fruits were separately analyzed. Ellagitannins were found to be the predominant phenolics in all samples except in PJAs. However, due to the low lignan amounts, only isolariciresinol could be quantitated in peels and mesocarp. The peels and mesocarp revealed highest contents of hydrolyzable tannins (27–172 g/kg and 32–263 g/kg, respectively) and isolariciresinol (4.9–19.8 mg/kg and 5.0–13.6 mg/kg, respectively). To the best of our knowledge, a systematic investigation of monomeric phenolic compounds and isolariciresinol considering diverse pomegranate fruits has been performed for the first time. The study demonstrates that raw material and extraction process have significant impact on juice composition and thus must be carefully selected. Furthermore, pomegranate processors should select juice extraction processes according to the final designation of the product, that is, distinguish between dietary products being rich in phenolic compounds having an astringent taste, and juices for consumption having an appealing taste but lower amounts of phenolics, respectively. This study may further contribute to facilitate authenticity control of diverse pomegranate products and help predict sensory and biofunctional characteristics of pomegranate juices.     

Anthocyanins characterization of 15 Iranian pomegranate (Punica granatum L.) varieties and their variation after cold storage and pasteurization

Anthocyanins (ACs) are phenolic compounds that are distributed widely in fruits and vegetables. Apart from imparting color to plants, ACs also have an array of health-promoting benefits. In this research, the amounts of major ACs of 15 pomegranate (Punica granatum L.) varieties obtained from Yazd province were determined. The major ACs detected in the studied varieties were as follows: delphinidin 3-glucoside (2.19–16.29 mg/L), delphinidin 3,5-diglucoside (2.36–63.07 mg/L), pelargonidin 3-glucoside (0.26–1.36 mg/L), pelargonidin 3,5-diglucoside (0.01–8.11 mg/L), cyanidin 3-glucoside (5.78–30.38 mg/L), and cyanidin 3,5-diglucoside (4.39–166.32 mg/L). The effect of storage time of unprocessed and pasteurized juices on ACs content of four selected varieties was also studied. Average degradation percentage of each AC was between 23.0 and 83.0% during 10 days at 4 °C. Moreover, in pasteurized juices average degradation of ACs was 42.8 ± 0.5% after 10 weeks storage at 4 °C.     

Characterization and evaluation of major anthocyanins in pomegranate (Punica granatum L.) peel of different cultivars and their development phases

Three red pomegranate cultivars of different coloration in China (Lvbaoshi, Hongbaoshi, Moshiliu) were analyzed quantitatively during ripening for individual anthocyanin (AC) pigment content. For the first time, anthocyanin peonidin-hexoside and flavonol myricetin-hexoside were tentatively identified in Moshiliu pomegranate. Cy3G, Pg3G, and Cy3,5dG were the first three major ACs in Hongbaoshi and followed a similar changing pattern with ripening time. Large amounts of Cy3G and Dp3G were found in dark red Moshiliu cultivar, exhibiting a similar pattern over time. The main concentration of Cy3G was 53.52 mg 100 g^?1, which was 35-fold and 12-fold higher compared to Lvbaoshi and Hongbaoshi cultivar. The main concentration of Dp3G reached 34.36 mg 100 g^?1 which was generally 68-fold and 82-fold higher than Lvbaoshi and Hongbaoshi. The main concentration of Cy3,5dG, Cy3G, and Pg3G levels in Hongbaoshi presented significant differences during ripening period (p < 0.05) compared with the Lvbaoshi cultivar. The AC profile was linked closely to the level of pigmentation. The results highlighted that cultivars and development phases influenced AC profile significantly. Data derived from study of the ratio between diglucosides and monoglucosides led to characterize the ACs in three different red pomegranate fruits.     

Antiproliferative and antioxidant activities of Turkish pomegranate (Punica granatum L.) accessions

The objective of this study was to assess antioxidant and antiproliferative activities of four different Turkish pomegranate varieties (Hatay, Hicaz, Adana and Antalya) using an in vitro HepG2 cancer cell model. All the pomegranate extracts employed in this study significantly diminish the proliferation of HepG2 cells in a dose‐dependent manner. The total phenolic acid, anthocyanin and flavonoid contents for each of the four varieties were determined. The Hatay pomegranate variety had the highest total phenolic acid (337.4 ± 2.34 mg/100 g) and flavonoid (58.42 ± 2.25 mg/100 g) contents of the pomegranates examined. Antioxidant activities of the pomegranates were determined using DPPH and ABTS radical scavenging assays. The lack of correlation between colour index value and antioxidant–antiproliferative activities suggested that phenolic acids and flavonoids are predominant compounds influencing pomegranate's bioactivity rather than anthocyanins. Individual phenolic acids found in Hatay pomegranates were determined, using an HPLC system, as gallic acid being the most predominant phenolic compound.     

Encapsulation of polyphenols and anthocyanins from pomegranate (Punica granatum) by spray drying

Pomegranate (Punica granatum) bioactive compounds (polyphenols and anthocyanins) of juice (PJ) and ethanolic extracts (PE) were encapsulated with maltodextrin (MD) or soybean protein isolates (SPI) by spray drying using a 2² statistical factorial design for each systems studied (PJ–MD, PJ–SPI, PE–MD and PE–SPI) considering the proportion of coating material and the inlet temperature as independent variables. The stability of the bioactive compounds microcapsules powders obtained under optimal conditions for each system was studied at 60 °C in oven for 56 days. The polyphenols encapsulating efficiency was significantly better in SPI matrix whereas for anthocyanins was in MD matrix. By the other hand, during the storage, the MD microcapsules provided a significant greater protective effect on the polyphenols and anthocyanins than SPI, as was shown by the lower degradation rate constants. When the microcapsules were added to yogurt the stability of the bioactive compounds followed a similar behaviour to those without encapsulation, except for PE–MD.     

The Effect of Sequential Fractionation Technique on the Various Efficacies of Pomegranate (Punica granatum L.)

The pomegranate (Punica granatum L.) is a fruit-bearing deciduous shrub. Various parts of this plant are used in the treatment of dyspepsia, bronchitis, hypotensive, throat inflammation, etc. and its nutritional value has well been accepted. In the present study, antioxidant and antimicrobial efficacy of different solvent fractions of P. granatum leaves was investigated. Fractionation was done sequentially in Soxhlet apparatus, using various solvents like petroleum ether, toluene, ethyl acetate, acetone, and water. Antioxidant activity was evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay, superoxide anion radical scavenging assay, and reducing capacity assessment. Total phenol and flavonoid content was also measured. The antimicrobial activity was assessed by agar well diffusion method against some of the tested food borne, pathogenic, and skin disease causing microorganisms. Antiulcer activity of the P. granatum acetone fraction (PGA) was evaluated using ethanol-induced gastric ulcer model. The PGA had maximum phenol content and had higher antioxidant activity. The PGA showed better DPPH free radical and superoxide anion radical scavenging activity than that of the standards. The results demonstrated that acetone fraction had potent gastroprotective and antisecretory effects. This study suggests that sequential fractionation technique is an excellent technique of extracting bioactive components of this plant at least. This study also demonstrated that PGA can serve as a potential natural source for use in food, nutraceutical, and pharmaceutical industry.     

Drying Kinetics and Energy Consumption in the Dehydration of Pomegranate (Punica granatum L.) Arils and Rind

The objective of this study was to evaluate the drying kinetics and energy requirements during convective drying (CD) (50, 60 or 70 °C), vacuum-microwave drying (VMD) (240, 360 or 480 W) and a combined method of convective pre-drying and vacuum-microwave finishing drying (CPD-VMFD) while processing pomegranate arils and rind. Drying kinetics of CD and VMD was described using seven basic drying models; however, VMFD was modeled only by the Henderson and Pabis equation. Pomegranate rind required less drying time (26–460 min) than arils (51–1,395 min) due to its higher porosity and lower sugar content. The drying time and the energy consumption were reduced when the air temperature and microwave wattage were increased. VMD required less energy than CD within the entire range of moisture content assayed. CD energy consumption can be reduced by its combination with VMD (CPD-VMFD), and this reduction was more important when the VMFD was applied earlier. VMD and CPD-VMFD are a good option for food drying industry in order to reduce both the drying time and the energy consumption while processing pomegranate arils and rind. Therefore, industries can optimise the drying process and consequently save their financial needs.     

Extraction and microencapsulation of bioactive compounds from pomegranate (Punica granatum var. Wonderful) residues

Pomegranate peels and seeds are industrial residues considered interesting sources of punicalagin (PU) and punicic acid (PA), respectively. To optimise their extraction process and protect them against environmental factors, pomegranate residues were extracted with supercritical CO₂ (SC‐CO₂) using a Box–Behnken design and then optimal extracts encapsulated by spray‐drying applying a 2² central composite design. Peel extracts showed a PU content of 0.4–9.5% with optimal extraction conditions of 400 bar, 43 °C and 20% ethanol. On the other hand, SC‐CO₂ seed extracts showed a PA content of 65.1–78.4% with 450 bar, 48 °C and 10% ethanol as optimal extraction parameters. Otherwise, the encapsulation efficiency of SC‐CO₂ extracts was significantly affected by core/wall material ratio and its quadratic effect. This parameter ranged from 35.1% to 72.4% for peel extracts and from 68.2% to 92.7% for seed extracts. Results showed that the proposed technologies are a feasible approach to the integral utilisation of residues from the pomegranate industry.     

田口法优化石榴皮中3种活性成分的提取工艺

采用田口法优化乙醇回流提取石榴皮中3种酚酸——安石榴林、安石榴苷和鞣花酸,并使3种成分产率达到最大。通过单因素试验和田口法优化显著影响石榴皮提取的因素,包括乙醇体积分数、提取温度、提取时间、液料比、粒径和提取次数。结果表明,优化后取得的乙醇体积分数、提取温度、提取时间、液料比、粒径和提取次数分别为20%、70℃、2 h、50︰1(mL/g)、0.125 mm和提取2次。在这些最佳条件下,从1 g干燥的石榴皮粉末中可获得17.89±0.27 mg安石榴林、498.66±2.13 mg安石榴苷、7.30±0.05 mg鞣花酸,与预测值17.94 mg安石榴林、497.44 mg安石榴苷、7.26 mg鞣花酸符合。因此,达到利用田口法使安石榴林、安石榴苷和鞣花酸3种成分产率最大的目标。     

Physico-chemical Properties, Vitamin C Content, and Antimicrobial Properties of Pomegranate Fruit (Punica granatum L.)

Pomegranate (Punica granatum L.) fruit is widely used in the food and process industries due to its excellent nutritional and health value and as a raw material for the manufacture of secondary products such as jellies, dyes, and cosmetics. The objectives of this research were to determine the vitamin C content and antimicrobial properties of fresh and dried fractions of fruit peel and arils of locally grown and imported pomegranate in Oman. A significant variation in vitamin C content was found among the five varieties of pomegranate studied, ranging from 52.8 to 72.0 mg/100 g fresh weight (fw) for arils and 76.8 to 118.4 mg/100 g fw for peels. Irrespective of the variety of pomegranate, vitamin C content in the peel was significantly higher than the aril, with differences ranging from 24.4% to 97.0% depending on variety. Fruit fractions showed antimicrobial effects (inhibition zone) on Staphylococcus aureus and Pseudomonas aeruginosa but not Escherichia coli. Sun drying of fruit peel significantly (p ≤ 0.05) enhanced vitamin C retention and antimicrobial effects in comparison with oven drying presumably due to lower rate of moisture removal associated with low temperature drying over longer duration in comparison with short-time high-temperature oven drying.     

Impact of processing and storage on the phenolic profiles and contents of pomegranate (Punica granatum L.) juices

Juices were obtained on pilot-plant scale from untreated, steamed and peeled pomegranate fruits (Punica granatum L.), respectively, by applying increasing pressures and various juice treatments, i.e., enzymatic treatment, filtration, clarification and pasteurization, to determine the influence of process technology on the phenolic profiles and contents of the juices. Polyphenols were characterized and quantified by HPLC-DAD-ESI/MSⁿ, and total phenolics and antioxidant capacity of the juices were determined by Folin–Ciocalteu, FRAP and TEAC assays, respectively. The total amounts of anthocyanins and colorless phenolics in the juices significantly differed depending on the applied technology. Highest phenolic recoveries were obtained from steamed fruits without further treatment. In contrast, lowest phenolic contents were determined in the juices produced from peeled fruits, i.e., the isolated seeds with adherent arils. With increasing pressures, polyphenol recoveries were enhanced, whereas juice treatments such as microfiltration and fining lowered phenolic contents of the juices. Furthermore, the amounts of individual phenolics were determined by HPLC-DAD with ellagitannins dominating the phenolic profiles. Juices solely produced from the edible parts of pomegranate exhibited lower amounts of ellagitannins compared with the juices from entire fruits. In contrast, the former juices were characterized by the highest amounts of gallotannins, hydroxybenzoic acids, hydroxycinnamic acids and dihydroflavonols. These results were consistent with the astringency of the juices. Additionally, storage experiments were performed at 4 °C and 20 °C in the dark and 20 °C under light exposure, revealing significant pigment degradation and concomitant color loss, especially at elevated temperatures and upon illumination, whereas the contents of non-anthocyanin phenolics and antioxidant capacity remained virtually unchanged throughout storage.     

Comparison of antioxidant activities of juice, peel, and seed of pomegranate (Punica granatum L.) and inter-relationships with total phenolic, Tannin, anthocyanin, and flavonoid contents

In this study, the antioxidant activities of juice, peel, and seed parts of pomegranate were investigated by using DPPH scavenging activity, β-carotene bleaching method, reducing power, and metal chelating activity. Sample of pomegranates which are named Punica granatum L. cv. Hicaznar, genotype 19–121, genotype 17–67, and genotype 19–66 obtained from BATEM (West Mediterranean Agricultural Research Institute) in Anlalya. The EC₅₀ values of DPPH scavenging activities in peel extracts (PE) had 23.4-fold higher than the juice extracts (JE), and the seed extracts (SE) had 2.3-fold higher than JE. The reducing power in peel extracts was found to be 4.7-fold higher than SE and 10.5-fold higher than the JE. The highest metal chelating capacity (37.22%) was determined in peel, while the lowest (7.151%) in seed. Generally, in peel, the total polyphenol, flavonoid, tannin contents, and in juice, the total polyphenol, anthocyanin, tannin contents, and acidity significantly affected to antioxidant activities.     

Optimisation of pomegranate (Punica Granatum L.) juice spray‐drying as affected by temperature and maltodextrin content

Pomegranate juice powder is easier to handle and has more potential applications than the concentrate. In this study, the response surface, 3‐level factorial design was used to evaluate the influence of spray‐drying conditions on the physicochemical properties of a powdered product obtained by drying pomegranate juice concentrate (PJC). It was spray‐dried with a lab‐scale spray‐dryer using 18 and 7 dextrose equivalent (DE) maltodextrins (MD) as drying‐aid agents. Adding MD significantly reduced the hygroscopicity and stickiness of the pomegranate juice powder, and thus yielded higher recovery. The maximum achieved ratio of PJC/MD was 1/1, and it was obtained with the use of DE7 MD. However, graphical optimisation studies resulted in 125–145 °C and 0.6–0.8 PJC/MD ratio as optimum variables to produce acceptable dried powder. The results indicated that increasing inlet air temperature increases solubility time and loss of anthocyanins and decreases bulk density and moisture content of the powder.     

Effect of pomegranate (Punica granatum) pomace extract as a washing agent on the inactivation of Listeria monocytogenes inoculated on fresh produce

Pomegranate pomace extract (PPE) was used as a substitute to chlorinated water for washing of fresh produce. PPE contained punicalagins and ellagic acids, and it had a good inhibitory effect against Listeria monocytogenes based on the results of disc diffusion test and time‐kill assay. Red chard, beet, chicon and red mustard leaves were treated with 7 mg mL^?1 PPE as a washing solution to inactivate L. monocytogenes inoculated on fresh produce and compared with 0.05 mg mL^?1 NaOCl treatment. After the treatment, L. monocytogenes population on the four leafy vegetables was reduced by 1.96–2.97 log CFU g^?1 compared to that on nontreated samples. The reductions in L. monocytogenes after PPE treatment were higher than those observed after NaOCl treatment. Further, the PPE treatment did not affect the surface colour of all fresh produce applied in this study. Thus, PPE can be used as an effective antimicrobial washing agent of fresh produce.     

Chemical Composition, Antioxidant Capacity, and Sensory Quality of Pomegranate (Punica granatum L.) Arils and Rind as Affected by Drying Method

The objective of this study was to evaluate the application of: (1) freeze drying, (2) convective drying (50, 60, or 70 °C), (3) vacuum–microwave drying (240, 360, or 480 W), and (4) a combined method of convective pre-drying and vacuum–microwave finish drying in the processing of pomegranate arils and rind. The quality parameters under study included sugars and organic acids, punicalagins and ellagic acid, total polyphenols, total antioxidant activity, and sensory quality. In general, drying led to a reduction in all studied parameters; however, the behavior of arils and rind was different. Vacuum–microwave drying at 240 or 360 W was the best drying treatment for arils, while rind required freeze drying or soft conditions of convective drying (50 °C). Further research is needed to obtain proper results with convective pre-drying and vacuum–microwave finish drying of arils and rind. With proper selection of the drying protocol, high-quality dried arils will be available for consumers; these arils will be characterized by high contents of fructose (25 g 100 g^?1), phytic acid (2.2 g 100 g^?1), punicalagins (0.57 mg g^?1), total polyphenols (1.6 mg eq gallic acid g^?1), high antioxidant capacity (0.6 mg eq Trolox g^?1), and high intensities of garnet color, sweetness, sourness, and fresh pomegranate aroma. Besides, dried rind with very high contents of active compounds (123 mg g^?1 of punicalagins and 108 mg eq gallic acid g^?1) and high antioxidant capacity (26 mg eq Trolox g^?1) will be also available as functional material.     

Effects of conventional and microwave heating on the degradation of olive oil

A comparative study was performed to evaluate the effects that microwave (12 and 15 min at 1,100 W) and conventional heating (36 and 45 min at 230 °C) have on olive oil (refined+virgin). The extent of the oxidative and hydrolytic degradation of the differently heated oils was evaluated by high performance size-exclusion chromatographic analysis of their polar compounds. The experimental results showed a great degradation of the oils with values of polar compounds higher than 26% at the most intense treatment. Significantly higher amounts of polar compounds, of triglyceride oligopolymers - known to have adverse effects on human health - and of oxidised triglycerides were found in microwaved than in conventionally heated oils, indicating a higher extent of oxidative degradation.     

Fruit quality of Italian pomegranate (<Emphasis Type=Italic>Punica granatum</Emphasis> L.) autochthonous varieties

Pomegranate is getting an increasing attention for its health-promoting effects. Collection and characterization of plants of local sources has been performed, and five accessions have been propagated and cultivated in a collection field for extra situ investigations. Accessions differ for pomological traits and chemical composition. Three of them, MG1, MG2, and MG3, belong to typology with low-medium acidity and high sugar content, while the other two, Tordimonte A and B, belong to typology with high acidity. In the juice and in the peels’ extract of Tordimonte A accession a high level of punicalin has been found through chromatographic determinations, while the presence of punicalagin was found in the juice of accession MG1. The accessions MG1, MG2, and MG3 seem particularly suitable for direct commercialization of fruits due to the fruit traits and quality (sweet varieties), while Tordimonte A and B could be valuable for juice processing (sour varieties).