Free Radical Scavenging Activity and Phenolic Content in Strawberry Fruit and Jam

Fresh fruit of three strawberry cultivars Fragaria ananassa × Duch. (cvs. ‘Clery’, ‘Honeoye’ and ‘NF 421’ (Asia)) were investigated and used to produce jams, which were analyzed before and after dark storage at 20 °C for six months. The aim of this investigation was to characterize all the samples in relation to the total phenolics, flavonoids, nonflavonoids, total anthocyanins and antioxidant activity. Among investigated strawberry fruit cv. Clery showed the highest amount of total phenolics, while regarding to total anthocyanins, cvs. ‘Honeoye’ and ‘NF 421’ showed higher amounts of total anthocyanins. The jam processing under applied conditions had appreciable effects on preserving stability of polyphenolics. Our results showed that total phenolics were more stable during processing in comparison with total anthocyanins. Furthermore, in all investigated samples flavonoids were predominant. Relevant differences among cultivars were observed when total phenolics, total anthocyanins, flavonoid and nonflavonoid contents in jams were compared. After six months storage, in all investigated samples anthocyanins were at least stable, without marked influences of cultivar. Compared to the strawberry fruits, the jams also represented a significant source of antioxidant compounds, even considering the lower content of phenolic compounds. Six month storage had influence on further decrease of antioxidant activity. Among investigated samples, the highest correlation was found in the total anthocyanins contents and the DPPH. Hence, the obtained results showed that besides fresh strawberry fruit, the strawberry jams also possess noticeable content of important bioactive compounds with considerable antioxidant activity

Sensory Profile of Plum Nectars

Nectars are beverages formulated with the juice or pulp of one or more fruits, with addition of water and sugar in various proportions depending on local taste, government standards, pH, and fruit composition of the variety used. Recently, the market for such products has greatly expanded. Consumers are looking even more for food with pleasant characteristics in terms of flavor, appearance and aroma. In this study, plum nectar samples, prepared by various recipes, were sensory evaluated to describe and compare its sensory characteristics. Plum (Prunus domestica L.) fruit was used to produce cloudy juice with small scale laboratory equipment. Before pressing on hydraulic press, fruits were depitted and chopped and treated with maceration enzymes at 48 ºC during 2 hours. After pressing, cloudy juice was pasteurized and used to produce plum nectars formulated to 12 % Brix with various contents of fruit (30 % or 60 %), with sucrose or fructose and addition of citric or malic acid. All prepared nectars were sensory evaluated by quantitative descriptive analysis (QDA). A research using different nectars showed signifi cantly better overall acceptance for a products formulated with 60 % as compared to those produced with 30 % of fruit content (p<0.05). The sensory acceptance of nectars was not signifi cantly affected by addition of different sugars or acids (p<0.05). Without influence of fruit content, sugar or acid addition, sensory attributes of aftertaste, tartness and off flavour were not expressed. Nectar with 60 % of fruit content, added sucrose and citric acid was evaluated as the most drinkable with high scores for all desirable attributes. The least accepted nectar was one with fruit content of 30 %, added fructose and mallic acid. Thus, some products presented good sensory acceptance suggesting commercial potential

Influence of Jam Processing Upon the Contents of Phenolics and Antioxidant Capacity in Strawberry fruit (Fragaria ananassa × Duch.)

Seven cultivars of strawberry (Diamante, Elsanta, Honeoye, Madeleine, Marmolada, Miranda and Miss) were analyzed for total phenols (TP), total flavonoids (TF), total nonfl avonoids (TN), total anthocyanins (TA) and antioxidant capacity (AC) before and after low sugar jam production to evaluate their changes after thermal processing. The content of TP, TF and TN were determined according to the Folin-Ciocalteu assay. Anthocyanins were determined by spectral method based on the bisulfite bleaching of monomeric anthocyanins. The antioxidant capacity was evaluated by ,2-diphenyl-1-picrylhydrazil radical (DPPH). Fresh fruits had total phenolics ranging from 251.97 to 713.06 mg gallic acid equivalent GAE/g of dry weight. In all investigated samples, fresh strawberries and jams, nonflavonoids were predominant phenols. Cultivar Honeoye had the highest amounts, while cultivar Miss had the lowest amounts of TP and TN. Cultivar Miranda had TF in the highest concentrations, while the lowest concentrations were found in cultivar Marmolada. TA for investigated cultivars was 63.55-177.71 mg Cy-3-G/100 d.w. with strong differences among cultivars. On the basis of dry weight the processing and heating during jam making generally decreased the contents of TP for 37-70 %. During processing, cultivar Madeleine showed the greatest stability of TP, TN and TF, while cultivar Elsanta showed the greatest anthocyanins stability. In comparison with fresh strawberry fruit, whose antioxidant capacity were in the range of 0.23 mmol TE/kg f.w. to 0.67 mmol TE/kg f.w., the jams also represent a noticeable source of antioxidant compounds, even considering the lower content of phenolic compounds, with the antioxidant capacity of 0.20 mmol TE/kg f.w. to 0.62 mmol TE/kg f.w. Hence, the obtained results showed that besides fresh strawberry fruit, the strawberry jams also possess noticeable content of important bioactive compounds with considerable antioxidant capacity

Determination of Flavonoids in Pulp and Peel of Mandarin Fruits

The aim of this study was to determine total flavonoids and individually flavanon glycosides as well as antioxidant capacity in pulp and peel of two mandarin groups, namely Satsuma (Citrus unshiu Marcovitch) cv. Saigon and Clementine (Citrus reticulate var. clementine) cv. Corsica SRA 63. Total flavonoids content was measured using colorimetric method, whereas HPLC-PDA detection was used for the analysis of individual flavanone glycosides (narirutin, naringin and hesperidin). In addition FRAP method was used to determine the antioxidant capacity. The results of colorimetric method showed that there was high concentration of flavonoids in all investigated samples, especially in peels (1156 mg/100 g in Satsuma peel and 804 mg/100 g in Clementine peel). Among the flavonone glycosides, hesperidin, was determined in the highest concentration in both investigated pulps. In peels flavanon glycosides were present in decreasing sequence as follow: narirutin>hesperidin>naringin. According to FRAP method, all samples possess an evident antioxidant capacity especially peels. Correlation between total flavonoids, hesperidin, naringin, narirutin and antioxidant capacity was very high with correlation coefficiants between 0.81 and 0.98

Utjecaj ekstrakcije potpomognute mikrovalovima na udjel fenolnih spojeva i antioksidacijski kapacitet cvijetova trnine

This research was undertaken to investigate the influence of extraction parameters during microwave-assisted extraction on total phenolic content, total flavonoids, total hydroxycinnamic acids and total flavonols of blackthorn flowers as well as to evaluate the antioxidant capacity by two different methods (2,2-diphenyl-1 picrylhydrazyl free radical scavenging capacity and ferric reducing antioxidant power assays). The investigated extraction parameters were: solvent type and volume fraction of alcohol in solvent (50 and 70 % aqueous solutions of ethanol and methanol), extraction time (5, 15 and 25 min) and extraction temperature (40, 50 and 60 °C) controlled by microwave power of 100, 200 and 300 W. Multivariate analysis of variance (MANOVA) was used to evaluate the differences at a 95 % confidence level (p≤0.05). The obtained results show that aqueous solution of ethanol was more appropriate solvent for extraction of phenolic compounds (total flavonoids, total hydroxycinnamic acids and total flavonols) than aqueous solution of methanol. The amount of phenolic compounds was higher in 70 % aqueous solution of ethanol or methanol, while higher antioxidant capacity was observed in 50 % aqueous solution of methanol. Higher temperature of extraction improved the amount of phenolic compounds and also antioxidant capacity determined by 2,2-diphenyl-1-picrylhydrazyl free radical scavenging capacity assay. Extensive duration of extraction (15- to 25-minute interval) has a significant effect only on the increase of total phenolic content, while specific phenolic compound content and antioxidant capacity were the highest when microwave extraction time of 5 min was applied.Ovo je istraživanje provedeno radi ispitivanja utjecaja parametara ekstrakcije potpomognute mikrovalovima na udjele ukupnih fenola, flavonoida, hidroksicimetnih kiselina i flavonola i određivanja antioksidacijskog kapaciteta cvijetova trnine pomoću dviju različitih metoda (DPPH i FRAP). Ispitani su sljedeći ekstrakcijski parametri: tip otapala i volumni udjel alkohola u otapalu (50 i 70 %-tna vodena otopina etanola i metanola), vrijeme ekstrakcije (5, 15 i 25 min) te temperatura ekstrakcije (40, 50 i 60 °C) održavana snagom mikrovalova od 100, 200 i 300 W. Multivarijantna analiza varijance (MANOVA) korištena je za procjenu razlika na razini pouzdanosti od 95 % (p≤0.05). Dobiveni rezultati pokazuju da je vodena otopina etanola prikladnije otapalo za ekstrakciju fenolnih spojeva (ukupnih flavonoida, hidroksicimetne kiseline i flavonola) od vodene otopine metanola. Udjel fenolnih spojeva bio je veći u 70 %-tnim vodenim otopinama etanola i metanola, dok je antioksidacijski kapacitet ekstrakata u 50 %-tnoj vodenoj otopini metanola bio veći. Viša temperatura ekstrakcije metanola povećala je udjel fenolnih spojeva i antioksidacijski kapacitet određen pomoću DPPH metode. Produljeno trajanje ekstrakcije (u intervalu od 15 do 25 min) bitno je utjecao samo na povećanje udjela ukupnih fenola, dok su udjel specifičnih fenolnih spojeva i antioksidacijski kapacitet bili najveći pri vremenu ekstrakcije od 5 min

The Polyphenols Stability, Enzyme Activity and Physico-Chemical Parameters During Producing Wild Elderberry Concentrated Juice

The influence of processing wild elderberry into concentrated juice on polyphenols (total phenols, flavonoids, non-flavonoids, anthocyanins, flavan-3-ols, hydrolysed tannins) stability, activity of polyphenol oxidase (PPO) and peroxidase (POD), and changes of physico-chemical parameters (total and soluble dry matter, total acidity, pH, sugars) were investigated. The amounts of total phenols, flavonoids, non-flavonoids, falvan-3-ols and hydrolysed tannins were analyzed using Folin-Ciocalteu colorimetric method, while the total anthocyanins were determined by bisulphite bleaching method. Total phenols ranged from 25.87 mg/g DM to 38.87 mg/g DM. Total anthocyanins were the most abundant polyphenols in all investigated samples (raw elderberries, elderberries after blanching, elderberry juice after disintegration and pressing, concentrated elderberry juice) and their concentration ranged from 13.12 mg/g DM to 25.67 mg/g DM. Other polyphenols determined in high concentration were hydrolysed tannins, followed by fl avan-3-ols, flavonoids and nonfavonoids. After blanching, the concentration of all polyphenols did not decrease significantly. After disintegration of elderberries the concentration of all polyphenols increased, probably due to inactivation of PPO and POD and better isolation of polyphenols from homogenized puree. During processing of elderberry juice into concentrated juice most polyphenols were stable. Total acidity and pH value were not changed during processing, whereas the amounts of total and reducing sugar increased after pressing and additionally after concentration. The obtained results suggest that raw elderberries as well as elderberry concentrated juice are high potential source of polyphenols especially anthocyanins

Određivanje udjela fenola i antioksidacijskog kapaciteta u sortama borovnice (Vaccinium corymbosum L.) uzgojenim na području sjeverozapadne Hrvatske

The aim of this study is to evaluate the content of phenolics: total phenols (TPC), flavonoids (TF), anthocyanins (TA), flavan-3-ols (TF3ols), as well as total antioxidant capacity (TAC) and reducing power (RP) in four blueberry cultivars (Vaccinium corymbosum L.) introduced in the Northwest Croatian climate conditions. Phenolic compounds were measured by spectrophotometric methods, TAC was determined using DPPH and ABTS assays and RP by FRAP assay. All cultivars contained high mass fraction of TPC, TF, TA and lower mass fraction of TF3ols. Among the researched fruits, Sierra cultivar contained the highest amounts of all groups of phenolics, followed by Elliott>Bluecrop≥Duke. Significant differences were observed in phenolic mass fraction among different cultivars and growing seasons (p<0.05), and phenolic compounds were significantly higher in growing season 2006. Examined cultivars possess high antioxidant capacity and reducing power, and all phenolics were highly correlated with TAC and RP (R=0.46 to 0.99). The study indicated that growing and climate conditions in Northwest Croatia are convenient for introducing blueberry cultivars. Generally, blueberry fruits are a rich source of phenolics, which show evident antioxidant capacity.Svrha je ovoga istraživanja odrediti udjel fenola: ukupne fenole (TPC), flavonoide (TF), antocijane (TA), flavan-3-ole (TF3ols), zatim ukupni antioksidacijski kapacitet (TAC) i redukcijsku snagu (RP) u četiri sorte borovnica (Vaccinium corymbosum L.) introduciranih u klimatskim uvjetima sjeverozapadne Hrvatske. Fenolni su spojevi određeni spektrofotometrijskim metodama, TAC je određen DPPH i ABTS metodama te RP FRAP metodom. Sve su sorte sadržavale veliku količinu TPC, TF, TA i manju količinu TF3ols. Među istraživanim sortama, sorta Sierra sadržavala je najveću količinu svih skupina fenolnih spojeva, zatim sorta Elliott te Bluecrop i Duke. Statistički značajne razlike utvrđene su u količini fenolnih spojeva različitih sorata te zbog sezone uzgoja (p<0.05). Udjeli fenolnih spojeva bili su veći u sortama uzgojenim tijekom 2006. Istraživane sorte imaju veliki antioksidacijski kapacitet i redukcijsku snagu, a sve skupine fenolnih spojeva pokazuju vrlo visoku korelaciju s TAC i RP (R=0,46 do 0,99). Istraživanjem je utvrđeno da uzgoj u klimatskim uvjetima sjeverozapadne Hrvatske pogoduje introdukciji istraživanih sorata borovnice. Općenito su plodovi borovnice bogat izvor fenolnih spojeva, koji pokazuju očigledan antioksidacijski kapacitet

Quality of Clementine Jam Influenced by Purée Pretreatment, Sugar Type and Pectin Addition

The aim of this research was to investigate the influence of several parameters on quality of Clementine (Citrus clementine) jam. Thermal treated and nontreated Clementine purée, two types of sugar (sucrose and fructose) and three different amounts of added pectin were used for the jam producing. Accordingly, twelve jams were prepared and sorted in four groups, two of nontreated purées and two of treated purées, and each one with sucrose and fructose within. The quality of jams was evaluated through gel strength measurement, sensory evaluation and level of polyphenols. The results of gel strength measurement showed that the treated purée jams were less firm than nontreated ones, the jams with sucrose were firmer than the ones with fructose and the gel strength of jams increased with amount of added pectin increase. Jams of nontreated purée contained higher level of polyphenols in comparison with jams of treated purée. Regarding to sensory evaluation, the nontreated purée jams were higher rated in comparison to treated ones. Furthermore, jams with fructose were better evaluated than jams with sucrose. Based on obtained results, it is revealing that nontreated purée jam with fructose and 0.7 % added pectin was the best sensory evaluated sample