Antioxidant Activity Of Juice Research Articles

Effect of heat treatment on the quality of citrus juices

The current study was designed to estimate the effect of heat treatment conditions on the quality of the pomelo and kinnow juice. The different temperature–time combination was selected to treat the juices. The quality of the juice was determined based on TSS, acidity, ascorbic acid content, total phenolic content, reducing sugar, antioxidant activity, and sweetness. After the heat treatment to both the juice, the samples showed a significant decrease in total phenolic content, reducing sugars, ascorbic acidity and antioxidant activity of juices as the duration and temperature of the treatment increases. The acidity of the product increases, while sweetness decreases with an increase in the time of treatment. It was also found that there is no significant change in the properties with an increase in the temperature of treatment. It was revealed that low-temperature low time can be used to get a good final quality in terms of ascorbic acid, antioxidant, and total phenolic content of both juices.

Effect of Ultrasonic, Thermal and Enzymatic Treatment of Mash on Yield and Content of Bioactive Compounds in Strawberry Juice

Strawberries are rich in bioactive compounds that may be of health importance. The technological process often significantly reduces the content of such compounds in the product. The study aimed to compare the effect of enzymatic, ultrasonic and thermal mash treatment on the content of ascorbic acid, anthocyanins, phenolic compounds and the antioxidant activity of strawberry juice. In addition, the effect of increased temperature assisting ultrasonic mash treatment and the use of a vacuum for a short period to remove air from the mash during pectinolysis was investigated. A significant increase in the efficiency of juice pressing was obtained for enzymatic treatment (by 40%), thermal and thermosonication (16%). It was found that the applied methods yield different results depending on the tested compounds. In the case of anthocyanin, the most effective method was thermosonication, which contributed to a 40% increase in their content. The enzymatic and thermal methods resulted in a two-fold increase in the content of phenolic compounds. The antioxidant activity of the juice from the treated mash (regardless of the method used) was significantly higher than samples from the untreated mash. A significant correlation (r = 0.77) was noted between antioxidant capacity and non-anthocyanin phenolic compound content in the tested juices.

Phenolic compounds and antioxidant activity of experimental and industrial table grape juices

Phenolic compounds are the third most abundant constituents in grapes and derivatives and are known to contribute to human health due to their antioxidant and anti-mutagenic effects and their ability to prevent pathologies such as cancer and cardiovascular diseases. Grapes and derivatives are among the most important sources of phenolics. The purpose of the present work was the evaluation of these compounds in experimental and industrial grape juices. Additional physico-chemical indices were also evaluated in order to complete the juices characterization. The experimental juices were separately produced from Italia and Red Globe table grapes cultivars by centrifugation and crushing. Three types of industrial grape juices (Italia cv.) were considered: A juice with medium sugar content; a juice with high sugar content; a strongly sulphited juice. Analyses were performed on the starting grapes and on the unpasteurized juices. The results showed a noticeable loss of phenolics during extraction although crushing was more efficient than centrifugation. In fact, the juices obtained by crushing showed higher phenolic contents than the juices obtained by centrifugation (16%–19% more total phenolics, 16%–31% more flavonoids, 7%–11% more flavanols reactive with vanillin, 100% more proanthocyanidins). Strong correlations among total phenolics and antioxidant activity of grapes and flavanols reactive with vanillin and antioxidant activity of juices were observed. The extraction methods significantly affected physico-chemical characteristics and antioxidant contents of the resulting juices since centrifugation mainly acted on pulps, while trituration involved the whole grape berries. Practical applications The paper was a preliminary research aimed to investigate, on a laboratory scale, the effects of the extraction methods on the quality features of grape juice. Nevertheless, it was intended to meet the requirements of juice producers interested in a successive scale up to pilot plants that could be also used for artisanal production. The paper can be considered as a guideline for small producers of natural functional juices. It demonstrated that it is not sufficient to choose the raw materials with the highest contents of nutraceuticals and that is important to analyze how the various available extraction systems act, in particular, if the starting material is a multi-component food as grape. Since the phenolic concentrations of the juices were lower than those of the corresponding grapes, it is reasonable to suppose that a part of the phenolic compounds was lost during the extraction step but also that most of the phenolics remained in the pomace. Although the by-products remaining after juice extraction were not analyzed, the paper suggested to think them not as wastes but as an economical source of nutraceuticals.

Early Season Foliar Iron Fertilization Increases Fruit Yield and Quality in Pomegranate

Early season foliar fertilization with different nutrients is a promising tool in pomegranate grown in poor, high pH soils. The effects of foliar fertilization with FeSO4 and the synthetic chelate Fe(III)-EDDHA (Fe(III)-ethylendiaminedi(o-hydroxyphenylacetate)) on fruit yield and physicochemical characteristics were assessed in a two-season field trial. Fertilizers were sprayed at full bloom and one month later, using Fe concentrations of 1.3 and 2.6 mM for FeSO4 and 1.1 and 2.1 mM for the Fe-chelate. Both doses of FeSO4 and the higher chelate dose increased leaf Fe concentrations and fruit yield, with the best results being observed with 2.6 mM FeSO4 (20–31% increases in yield). On the other hand, leaf N, P, K, Ca, and Mn concentrations were not affected by foliar Fe fertilization. The only treatment that increased the number of fruits per tree, aril juice content and juice total soluble solids and decreased juice total acidity in both seasons was 2.6 mM FeSO4. Both FeSO4 doses caused consistent increases in the maturity index and total sugars in juice, along with minor decreases in juice total phenolic compounds. The antioxidant activity in juice was slightly decreased by 2.6 mM FeSO4. In conclusion, early season foliar Fe fertilization had positive effects on pomegranate yield and quality, with FeSO4 being better than Fe(III)-EDDHA.

Влияние предварительной обработки ягод клюквы на экстракцию антоциановых пигментов, выход сока и его антиоксидантную активность

Предпочтения производителей и потребителей пищевых продуктов ориентированы на использование натуральных ингредиентов, в том числе натуральных красителей. Признанным источником красных пищевых красителей – антоцианов является дикорастущая ягода – клюква обыкновенная Vaccinium oxycoccos L. Разработка эффективной технологии переработки ягод, обеспечивающей наиболее полную экстракцию в сок антоциановых соединений, позволит получать ягодные соковые ингредиенты с высоким содержанием природных антоциановых красителей и других биологически активных веществ ягод для применения в составе рецептур пищевых продуктах. Проведены исследования по экспериментальному обоснованию и разработке условий предварительной обработки ягод клюквы при получении сока с применением различных способов (бланширование, СВЧ, УЗ, ферментативная обработка), обеспечивающие наиболее полную экстракцию в сок антоциановых соединений. Установлено, что проведение предварительной обработки ягод клюквы при получении сока с помощью пресса оказывает существенное влияние на выход сока, экстракцию антоцианов и антиоксидантную активность сока. Экспериментально установлено, что применение УЗ и СВЧ предобработки ягод клюквы в разработанных условиях способствует увеличению выхода сока на 16-27 мас. (или об.)%, антоцианов - в 1,5-1,9 раза, антиоксидантной активности сока- в 1,1 и 1,2 раза. Более эффективными являются предварительная стадия бланширования и проведение ферментативной обработки с использованием МЭК на основе Фруктоцим П-6Л и Laminex BG2: выход сока увеличивается в 2,5 и 1,3 раза, антоцианов – в 3,0 и 2,2 раза, антиоксидантная активность сока возрастает в 1,3 и 1,25 раза соответственно по сравнению с аналогичными показателями, установленными для соков, полученных из ягод клюквы, не подвергавшихся предварительной обработке. Выявлено, что проведение предобработки ягод клюквы не приводит к качественным изменениям состава антоциановых соединений сока и их количественных соотношений. Показано, что антоциановый профиль клюквенных соков представлен шестью антоцианами на основе цианидина и пеонидина, углеводными компонентами выступают глюкоза, галактоза, арабиноза. Преобладающими антоцианами являются цианидин-3-галактозид (24,6-25,0%) и пеонидин-3-галактозид (28,7-31,4%).

Use of Autochthonous Lactobacilli to Increase the Safety of Zgougou.

Seeds of Pinus halepensis are used for preparing zgougou, a spontaneously fermented matrix giving juice and seeds debris, consumed in many Arabian countries, including Tunisia. In the same way as all the food processes based on spontaneous fermentation, zgougou hides health risks due to eventual pathogenic microorganisms and derived toxins. This study aimed at investigating the effect of the use of autochthonous Lactobacillus paraplantarum A1 and Lactobacillus plantarum A2, as fermentation starters, on the microbiological characteristics, profiles of volatile organic compounds (VOC), antibacterial and antioxidant activities of juice and seeds debris from zgougou. The starter lactobacilli inhibited undesired bacteria (e.g., Enterobacter and Aeromonas) and coccus-shaped lactic acid bacteria, as shown by culture-dependent and-independent methods. The inhibitory effect was more evident in juice than in seeds debris. Some VOC (ethanol, acetoin, phenol,2-methoxy and caryophyllene) were present at higher concentrations in juice and seeds obtained upon spontaneous fermentation, compared to the samples deriving from fermentation with lactobacilli. The latter samples were characterized by higher concentrations of acetic acid, decane, 1-nonanol, bornyl acetate and bornyl formate. In addition, they showed a wider spectrum of antibacterial activity than spontaneously fermented juice and seeds. The use of autochthonous lactobacilli did not relevantly affect the antioxidant activity of zgougou. When juice from lactobacilli-driven fermentation was used to prepare a traditional Tunisian pudding (“Assidat-Zgougou”), it improved color and odor with respect to the pudding containing juice from spontaneous fermentation. This study showed that the use, at laboratory scale, of autochthonous lactobacilli is a feasible biotechnological tool to outgrow undesired bacteria, thus improving the safety of zgougou juice. Future studies should be undertaken to confirm the observed benefits at industrial scale.

Application of digital images and multivariate calibration for the quantification of anthocyanin and antioxidant activity in grape juice

Background and Aims The current methods for measuring the anthocyanin concentration (AC) and antioxidant activity (AA) of grape juice have limitations. The objective of this work was therefore to evaluate the application of digital imaging as a simple, fast and low‐cost method for determining AC and AA in juice. Methods and Results The AC and AA of 75 grape juice samples were measured using reference methods and then correlated against digital images of 200 dpi resolution obtained with a scanner, using partial least squares regression. The samples were separated with the Kennard–Stone algorithm into calibration sets (50 samples) and external validation sets (25 samples). The models used for the quantification of AC and AA presented a root mean square error of calibration of 8.8 mg/L and 9.8 μmol and a root mean square error of prediction of 7.5 mg/L and 8.0 μmol, respectively. The correlation coefficients for the adjustment were 0.8479 and 0.9258 for the models in the determination of AC and AA, respectively. Conclusions Digital imaging and multivariate calibration can be used to measure efficiently selected parameters of grape juice composition. Significance of the Study Analytical methods based on digital imaging offer promising alternatives to conventional methods, since they are fast, simple, non‐destructive and employ little or no chemical reagents, thereby reducing analysis costs and facilitating in situ analysis.

Total anthocyanin, flavonoid, polyphenol and tannin contents of seven pomegranate cultivars grown in Iran.

Pomegranates are healthy fruits rich in bioactive phytochemicals and widely consumed in  the human diet. This study was designed to assess their physico-chemical properties and total polyphenolic compounds, along with antioxidant and ascorbic acid concentrations of the skin and juice of seven unstudied pomegranate cultivars grown in Iran. Ten fruits of each of seven selected cultivars were picked. Methanolic extracts from the fruit skins as well as juices were subjected to an evaluation of their physico-chemical properties and phenolic content. From the pomegranate cultivars studied, the highest juice concentration was measured in ‘Zagh- -e-Zabol’ (72.9 ±2.55%). The highest total soluble solids (18.79 ±1.06 oBrix) of juice, as well as the highest ascorbic acid (16.54 ±2.09 mg/100 g) and total anthocyanin content of skin [11.20 ±2.4 mg CyE (cyanidin- -3-glucoside equivalent)/L] were measured in ‘Bajestan’. Total flavonoids were more concentrated in the skin of ‘Siah-e-Zabol’ [930 ±16 mg QuE (quercetin equivalent)/L]. In the juice of ‘Rabab-e-Pust Ghermez’ and ‘Malas-e-Saveh’ the highest concentrations of phenolic compounds were recorded [1082 ±12.8 mg GaE (gal- lic acid equivalent)/L] and tannins [6.55 ±0.5 mg TaE (tannic acid equivalent)/L], respectively. Significant differences were assessed between the skin and juice of the cultivars in terms of their physico-chemical properties and polyphenolic contents. The results showed higher levels of total tannins, phenolics and antioxidant activity in juice of pomegranate, whereas the skins possessed higher total flavo- noid, anthocyanin and ascorbic acid content. Further phytochemical analysis are therefore needed to identify the most representative phenylpropanoids by LC-MS (liquid chromatography coupled to mass spectrometry) and to develop novel and promising dietary supplements.

Physicochemical characteristics, bioactive compounds and antioxidant activity in juice, pulp, peel and seeds of Cantaloupe melon

Although it is known that fruit products are rich sources of natural bioactive compounds, information on the nutritional value of their waste parts is scarce. The objective was to characterize the edible (juice and pulp) and waste (peel and seeds) parts of Cantaloupe melon (Cucumis melon L. var. reticulatus) in terms of some physicochemical characteristics, bioactive compounds and total antioxidant activity. Juice, pulp, peel and seeds represent 42, 23, 25 and 7% of total weight, respectively. Juice and pulp presented identical profiles in terms of physicochemical characteristics, bioactive compounds and antioxidant activity. They contributed to the majority of the overall content of carotenoids (80%) and vitamin C (84%) in Cantaloupe. Peel and seeds had the highest concentrations of potassium, being seeds the richest portion (7.08 ± 0.16 mg/g). Seeds had also the significantly highest total phenolics concentration (229.13 ± 20.92 µg/g), antioxidant activity (653.67 ± 169.20 µg/g), and soluble solids content (11.79 ± 0.90 °Brix). Peel stood out by the presence of chlorophylls. Since waste parts of Cantaloupe melon represent around 32% of total weight, their valorization is a challenge and strategies to improve ways of re-using them should be developed.

Effect of Pre-fermentation Maceration on the Content of Antioxidant Compounds in Grapevine Juice

Lower antioxidant capacity of white wines is caused by a lower content of phenolic compounds. In red wine, a higher content of phenolic compounds is the result of maceration. This study deals with effects of pre-fermentation maceration on contents of some selected compounds (above all antioxidants) in juices made of grapes of white varieties 'Welschriesling', 'Green Veltliner' and 'Neuburger'. The grapevine mush was macerated for 0; 2; 4; 8; 12; 24 and 48 hours. The spectrophotometry methods was used to estimate juice antioxidant activity and content of flavanols, anthocyans, catechins, hydroxycinnamic acids and flavonols. Contents of total titratable acids and pH were estimated as well. Results of this study show increasing tendency of all parameters with length of maceration. The highest content of antioxidants were found out in the variety 'Welschriesling'. Important are increasing values of hydroxycinnamic acids. However, the main role of the phenolics acids is to contribute to the anti-oxidant capacity, the tartaric esters of hydroxycinnamic acids (particularly caftaric acid) are centrally involved in oxidation and browning reactions in white wine. Their levels increased during the whole period of maceration. In 'Welschriesling', their content increased by 74 mg·L-1. Decreasing tendency show results of titratable acids. Their contents decreased within the first 12 hours of maceration and thereafter they do not change. Longer must maceration could contribute to a decrease in contents of total titratable acids and, thus, to a better harmony of produced wine.

Quality assessment of juice prepared from different varieties of currant (Ribes L.)

In the Slovak Republic currants are traditionally grown species of small fruits mainly in house gardens. Although currently their area is very small compared to the other types of fruit. We can see the importance of growing this genus (Ribes L.) in its good adaptability to climate conditions, in small growing demands and in stable production of nutritionally highly valuable fruit. Currant berries as well as fresh currant juice are characterized by the presence of whole complex of antioxidant active substances. The aim of this study was to evaluate the nutritional quality of currant juice prepared from various species and varieties of genus Ribes (L.). based on the content of their total polyphenols, anthocyanin dyes and antioxidant activity. In work we used varieties Blanka, Primus, Viktória, Heinemannova neskorá, Red Lake, Treny, Jonkheer van Tets, Fertödi, Titania, Triton and Öjebyn. Contents of evaluated components were assessed spectrophotometrically. Total polyphenol content of monitored samples determined by the Folin-Ciocalteu method reached values from 1897.43 mg GAE.dm-3 DM to 3712.21 mg GAE.dm-3 DM. The highest one was in juice from variety Primus and the lowest from variety Blanka. In white varieties of currant, the presence of anthocyanin dyes was immeasurable. In varieties of red and black currant anthocyanin dye content achieved values from 1947.64 mg.dm-3 DM (Jonkheer van Tets) to 4161.07 mg.dm-3 DM (Heinemannova neskorá). The antioxidant activity determined by the FOMO method reached values from 4130.42 mg AA.dm-3 DM to 6571.69 mg AA.dm-3 DM. We recorded the highest antioxidant activity in juice of variety Fertödi and the lowest of variety Primus.

Technological characteristics and selected bioactive compounds of Opuntia dillenii cactus fruit juice following the impact of pulsed electric field pre-treatment

Selected technological characteristics and bioactive compounds of juice pressed directly from the mash of whole Opuntia dillenii cactus fruits have been investigated. The impact of pulsed electric fields (PEF) for a non-thermal disintegration on the important juice characteristics has been evaluated in comparison to microwave heating and use of pectinases. Results showed that the cactus juice exhibited desirable technological characteristics. Besides, it also contained a high amount of phenolic compounds being the major contributors to the overall antioxidant activity of juice. HPLC-DAD/ESI-MSn measurements in the fruits’ peel and pulp showed that isorhamnetin 3-O-rutinoside was determined as the single flavonol found only in the fruit’s peel. Treating fruit mash with a moderate electric field strength increased juice yield and improved juice characteristics. Promisingly, the highest release of isorhamnetin 3-O-rutinoside from fruit’s peel into juice was maximally achieved by PEF.

Phenolic compounds in juices of apple cultivars and their relation to antioxidant activity

Apples and their juices are important sources of phenolic compounds in human diet. Using the same juice processing method, we compared phenolic composition as well as antioxidant activity of juices from various table apple cultivars, grown at the same location. Antioxidant activity of apple juices was estimated by application of two assays, ABTS cation radical decolorization and by scavenging of reactive oxygen species (ROS) generated by xanthine/xanthine oxidase (O 2 · - , H 2 O 2 , OH · ; superoxide assisted Fenton reaction), as measured by inhibition of ethylene release from KMB (α-Keto-γ-(methylthio)butyric acid). The apple juices differed in phenolic content and antioxidant activity, where cultivar differences were more relevant than environmental factors. Furthermore, to improve antioxidant performance in the XOD-test, a juice low in phenol content was supplemented with the appropriate amounts of phenols to the level of the best juice indicating that these phenolics contribute to the antioxidant activity of the apple juice. In ac­cordance to literature, the phenolic compounds re­presenting the main anti­oxidant activity in the apple juices comprise flavan-3-ols and chlorogenic acid.

Phenolic Compounds and Antioxidant Activity of Juices from Ten Iranian Pomegranate Cultivars Depend on Extraction

Phenolic compounds and antioxidant activities of ten juices from arils and whole pomegranate cultivars grown in Iran were studied. Phenolic contents and antioxidant activities of juices from whole pomegranate fruit were significantly higher than juices from pomegranate arils, but the variety has a greater influence than the processing method. The main phenolics in the studied juices were punicalagin A (5.40–285 mg/L), punicalagin B (25.9–884 mg/L), and ellagic acid (17.4–928 mg/L). The major and minor anthocyanins of cyanidin 3,5-diglucoside (0.7–94.7 mg/L), followed by cyanidin 3-glucoside (0.5–52.5 mg/L), pelargonidin 3,5-diglucoside + delphinidin 3-glucoside (0–10.3 mg/L), delphinidin 3,5-diglucoside (0–7.68 mg/L), pelargonidin 3-glucoside (0–9.40 mg/L), and cyanidin-pentoside (0–1.13 mg/L) were identified; the latter anthocyanin as well as cyanidin-pentoside-hexoside and delphinidin-pentoside were detected for the first time in Iranian pomegranates. The total phenolic contents were in the range of 220–2931 mg/100 mL. The results indicate that the pomegranate phenolics are not only influenced by extraction method but also—and even more—affected by the cultivar. Moreover, a good correlation was observed between total phenolic content and ABTS and FRAP methods in all pomegranate juices (>0.90). The results of current research can help to select the pomegranate cultivars for commercial juice production.

Comparison of Ascorbic Acid, Total Phenolic Content and Antioxidant Activities of Fresh Juices of Six Fruits Grown in Oman

Background: Regular consumption of fruits and their juices play a beneficial role in the prevention of many diseases owing to the presence of dietary antioxidants such as ascorbic acid, flavonoids and polyphenols. Aim: The aim of the study was to analyze and estimate total phenolics, ascorbic acid content and to investigate free radical scavenging activity of six locally grown and commonly eaten fruits in Oman. Methods: The fruits were thoroughly washed and mechanically squeezed to obtain the juices. The fruit juices after filtration were analyzed for total acidity, ascorbic acid, total phenolic content and in- vitro antioxidant activity by alkalimetery, iodimetric (volumetric), Folin Ciocalteu reagent (colorimetric) and 1,1, diphenyl picrylhyrazyl (DPPH) assay methods respectively. Key findings: Lime juice was found to be the most acidic while grapefruit juice had the maximum ascorbic acid content. Total phenolic content of the juices were observed in the following order of decreasing levels; pomegranate>grapefruit>lemon>lime>s weet melon>watermelon. The result of in- vitro antioxidant activity of all juices, barring watermelon and sweet melon, were quite significant, but the highest scavenging activity of DPPH radicals was exhibited by pomegranate juice closely followed by grapefruit and lemon juices respectively. Conclusion: The Results of this study indicated that these fruits are important to the consumer’s health and a potential source of dietary antioxidants due to their high phenolic and ascorbic acid contents.

Physicochemical Changes and Antioxidant Activity of Juice, Skin, Pellicle and Seed of Pomegranate (cv. Mollar de Elche) at Different Stages of Ripening.

In the present work, we investigate how the degree of ripeness (low, low-medium, medium and medium-high) affects the physical and compositional changes, as well as antioxidant properties of pomegranate fruit (cv. Mollar de Elche). The skin, pellicle, seed and juice were analysed. The fruit mass increased and the fruit skin became reddish (higher a* and lower h*) as the fruit ripening progressed. The lowest concentrations of flavonoids and hydrolysable tannins were recorded in skin and pellicles at medium-high maturity stage, which explains the decrease in the total phenols and reducing power during ripening of pomegranate. On the contrary, the highest concentration of flavonoids (165 mg of quercetin equivalents per 100 mL of juice) was determined in the juice at the most advanced ripening stage, concomitant with the highest total phenols (1695 mg of gallic acid equivalents per 100 mL of juice). Higher DPPH scavenging activity and an increase in the reducing power of juice were also observed during ripening. The trend of the above-mentioned properties allowed describing the fruit development and maturity.

A comparative analysis of the antioxidant activity of Kalanchoe juices

A study of the biological, including the antioxidant, activity of various medicinal plants with the aim of searching for the most active sources of biologically active compounds among them is, at present, of interest. In the present work, a comparative analysis of the antioxidant activity of juices from 14 Kalanchoe species, measured by the ammetric, voltammetric, and chemiluminescence methods has been performed. Among the samples examined, two members of the Kalanchoe genus were shown to have the highest antioxidant activity: Kalanchoe scapigera and K. rhombopilosa. They may appear to be richer sources of biologically active compounds compared with the currently used Kalanchoe species.

Characterization of pomegranate (Punica granatum L.) genotypes collected in Puglia region, Southeastern Italy

The popularity of pomegranate (Punica granatum L.) is increasing among growers and consumers due to its nutritional value, nutraceutical properties and adaptability to different soils and climate conditions. Pomegranate is characterized by a large variability in terms of domestic, wild and ornamental genotypes, and for seed-hardness, juiciness, rind and aril color, sugar/acid ratio, antioxidant activity, fatty acids, phenols and arils anthocyanins content. Evaluation of pomegranate germplasm has usually been performed using fruit morphological and chemical traits, whereas genetic studies received less attention. The aim of the present work was: (a) to carry on a morphological and biochemical characterization of a set of pomegranate genotypes collected in Puglia region, Southeastern Italy and (b) to investigate genetic diversity by microsatellite markers. A two-year study was carried out for the evaluation of 13 pomegranate genotypes, sweet and sour, of Italian and Israeli origin. Significant differences were observed for many of the parameters investigated, in particular fruit and aril size and maturity index of fruits, titratable acidity, total polyphenol content and antioxidant activity of juices and oil content of seeds. Genetic analysis on the pomegranate collection identified 53 SSR loci able to distinguish the different genotypes and to estimate genetic distances. In the dendrogram, pomegranate genotypes clustered according to both geographical origin and morphological–chemical traits (skin color, size, taste and polyphenolic content), suggesting that SSR markers could be effective to detect the genetic diversity of pomegranate, thus facilitating the exploitation of this fruit species germplasm. In general, morphological, chemical and genetic parameters allowed to clearly distinguish the Italian genotypes from the Israeli ones.

Selection of Process Conditions for High Pressure Pasteurization of Sea Buckthorn Juice Retaining High Antioxidant Activity

Sea buckthorn berries juice is a nutritious beverage, rich in vitamin C and carotenoids with high antioxidant activity. The main requirements for a freshly squeezed sea buckthorn juice production are the cloud stability and antioxidant activity retention after processing. Appropriate process technologies and conditions have to be applied in order to inactivate pectin methyl esterase (PME), responsible for cloud loss, while maintaining the nutritional characteristics and antioxidant activity of the juice. The objectives of the present work were to study and model the effect of thermal treatment and high pressure (HP) processing on the inactivation kinetics of endogenous PME and on total antioxidant activity alteration. Thermal treatment significantly affected PME inactivation and residual antioxidant activity. Processing even at mild process conditions (60 °C for 1 min) resulted in 2.5-fold antioxidant activity reduction and 50 % PME inactivation compared to untreated sample. Pressure and temperature acted synergistically for PME inactivation that followed first-order kinetics with a residual PME activity at all pressure–temperature combinations used (200–600 MPa and 25–35 °C). The effect of temperature and pressure on the inactivation rate constants was expressed through the activation energy and activation volume, respectively. Values of 163 kJ/mol and −17 mL/mol at reference pressure of 600 MPa and reference temperature of 35 °C were estimated, respectively. Antioxidant activity of the samples was expressed through the determination of the effective concentration (EC50). A slight increase in sea buckthorn antioxidant activity when applying pressures (200–600 MPa) at ambient temperature (25 °C) was observed compared to the corresponding value of untreated juice. Processing at higher temperatures did not significantly alter the total antioxidant activity of sea buckthorn juice. For sample treated at 600 MPa–35 °C for 5 min, a 5 % reduction of total antioxidant activity was observed. These conditions are proposed as effective process conditions for sea buckthorn juice cold pasteurization, based on the higher antioxidant activity retention and simultaneous PME inactivation.

Phytochemical Polyphenol Extraction and Elemental Composition of Vitis labrusca L. Grape Juices Through Optimization of Pectinolytic Activity

Grape juice is a natural source of polyphenols with potential health benefits. The aim of this study was to assess the optimized basis of the pectinolytic activity through a multivariate design for the bioactive enrichment of polyphenols in grape juices and to evaluate the effect of pectinases on the extraction of minerals by ICP-MS and FAAS. Grape juices were treated with pectinases Everzym® Color and Rapidase® Smart at different conditions of enzyme concentration (0.16–1.84 g L−1), temperature (14.8–83.6 oC), and incubation time (9.6–110.5 min), and the effect on total phenolics, anthocyanin content, and antioxidant activity of juices were determined by employing a second-order central composite design in combination with response surface methodology. The different conditions showed significant variations in polyphenol levels of grape juices. For both of the enzymes, the increase of temperature and enzyme concentration led to a higher extraction of polyphenols, with a significant effect. Estimated effects depict a good correlation among dependent variables. For Rapidase, the optimized extraction of polyphenols was determined at an enzyme concentration of 1.57 g L−1 and at a temperature of 54.8 oC. For Everzym, higher concentrations of polyphenols were obtained at the enzyme concentration of 1.30 g L−1 at 46.8 oC. The extraction using the Rapidase enzyme significantly increased the levels of Na, K, Mg, and Fe in grape juices (p < 0.05). The pectinolytic activity increased the polyphenol and mineral concentrations in grape juices. In addition, the optimal conditions of the pectinolytic treatment comprise a feasible alternative to improve the bioactive potential of grape juices.