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

“Fresh-cut” krumpir tretiran eteričnim uljem komorača tijekom skladištenja pri 8 °C

The aim of this study was to investigate the effect of treatment with fennel essential oil (FEO) on the shelf life of fresh-cut potatoes (FCP) and on the sensory characteristics of raw and subsequently boiled and fried potatoes. Peeled and sliced potatoes were immersed in an aqueous solution containing different FEO concentrations (0 (water control), 25, 125, and 250 mg L-1) for 15 min, then drained, vacuum packaged, and stored at 8 °C for 12 days. The CIELAB color parameters and aerobic mesophilic bacteria count (AMB) of the raw FCP and the sensory characteristics of the raw, boiled and fried samples were determined. AMB decreased with increasing FEO content, and this trend was generally maintained during storage. Slight negative changes in color were observed with increasing FEO content and with storage time. Fennel taste and odor in raw and boiled potatoes increased with increasing FEO content, while FEO odor after frying was only slightly pronounced in FEO-250 on day 0. Despite the antibacterial activity of FEO, spoilage of FCP was not prevented during storage. In general, after 6 days, the best results in terms of absence of browning and off-odor of raw and off-taste and sour taste of boiled and fried FCP were obtained with 25 mg L-1 FEO treatment.Cilj ovog istraživanja bio je ispitati učinak tretiranja eteričnim uljem komorača (FEO) na rok trajanja svježe rezanog krumpira (FCP) te na senzorske karakteristike sirovog te naknadno kuhanog i prženog krumpira. Oguljeni i narezani krumpiri potopljeni su 15 min u vodenu otopinu koja je sadržavala različite koncentracije FEO (0 (kontrola-voda), 25, 125 i 250 mg L-1), zatim su ocijeđeni, pakirani u vakuumu i pohranjeni pri 8 °C tijekom 12 dana. Određivan je broj aerobnih mezofilnih bakterija (AMB) sirovog FCP te su analizirani CIELAB parametri boje i senzorske karakteristike sirovih, kuhanih i prženih uzoraka. S povećanjem koncentracije FEO AMB se smanjio, a taj se trend uglavnom zadržao i tijekom skladištenja. S povećanjem koncentracije FEO i s vremenom skladištenja uočene su blage, ali negativne promjene boje. U sirovom i kuhanom krumpiru svojstva okusa i mirisa komorača povećavale su se s povećanjem udjela FEO, dok je miris FEO nakon prženja bio tek neznatno izražen i to u FEO-250 0-tog dana. Unatoč antimikrobnom djelovanju FEO, kvarenje FCP-a tijekom skladištenja nije spriječeno. Općenito, nakon 6 dana, najbolji rezultati s obzirom na boju i odsutnost neugodnog mirisa sirovog te neugodnog i kiselkastog okusa kuhanog i prženog FCP postignuti su tretmanom s 25 mg L-1 FEO

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

Functional and sensory properties of olives fortified spreadable cheese

Cilj ovog rada bio je ispitati utjecaj tipa (crne i zelene) i udjela masline na kvalitetu i senzorska svojstva sirnog namaza s maslinama. U uzorcima polaznih sirovina te pripremljenog sirnog namaza s maslinama određeni su ukupna suha tvar, pH vrijednost, boja (kolorimetrijski), sadržaj ukupnih fenola Folin-Ciocalteau metodom i antioksidacijski kapacitet (FRAP). Nadalje, uzorci sirnog namaza senzorski su ocijenjeni kvantitativnom deskriptivnom analizom (QDA). ANOVA je pokazala da su primijenjeni izvori varijacija značajno utjecali na većinu ispitivanih parametara. Uzorci s crnim maslinama imali su nešto viši udio suhe tvari, pH vrijednost te tamniju i zasićeniju boju. Određeni sadržaj ukupnih fenola i antioksidacijski kapacitet ukazuju na dobar potencijal sirnog namaza s maslinama kao funkcionalne hrane, gdje su uzorci sa zelenim maslinama sadržavali više ukupnih fenola i antioksidacijski kapacitet. Općenito, senzorska svojstva svih uzoraka su vrlo dobro ocijenjena, što upućuje na njihovu dobru prihvatljivost kod potrošača. Uzorci s crnim maslinama postigli su više ocjene za harmoničnost arome i ukupnu prihvatljivost, gdje se uzorak sirnog namaza s najvišim udjelom maslina istaknuo najvišim ocjenama za navedena svojstva.The aim of this work was to investigate the influence of olive type (green and black) and content on quality and sensory properties of spreadable cheese with olives. Total solids, pH value, colour (colourimetric), total phenols by Folin-Ciocalteau method and antioxidant capacity (FRAP) of the raw materials as well as of the prepared samples were examined. Furthermore, samples of spreadable cheese with olives were sensory evaluated using the Quantitative Descriptive Analysis (QDA). ANOVA showed that the applied sources of variation significantly affected the majority of investigated parameters. Samples with black olives had slightly higher dry matter content and pH value, and were characterized by darker and dull colour. The determined total phenols contents and antioxidant capacity showed a good potential of spreadable cheese with olives as a functional food, whereby green olives samples had higher total phenols content as well as antioxidant capacity. Generally, sensory properties of all samples were very well scored, indicating their good acceptability by consumers. Samples with black olives accomplished higher scores for flavour harmony and overall acceptability, where spreadable cheese with the highest olive content emphasized with the highest scores for these properties

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

Physicochemical Composition, Phenolic Content and Antioxidant Activity of Sour Cherry cv. Marasca During Ripening

Sour cherry cv. Marasca is Dalmatian cultivar from XVI century. Cultivation is limited on the north and central part of Dalmatia and on the part of the islands, where it achieves the best quality of fruit, high content of dry matter and sugar respectively, agreeable aroma and intense color. Sour cherry cv. Marasca is source of biologically active ingredients, organic and inorganic compounds, dietary fibers, aromatic compounds and high content of phenolic compounds, particularly anthocyanins and hormone melatonin. Many epidemiological studies showed that phenolic compounds have antioxidant and anti-inflammatory properties, and they have beneficial effect on human health. Marasca is rich with mentioned compounds. Physicochemical composition (total and soluble dry matter, pH value, total acidity) during ripening of cv. Marasca ecotype Recta (Cerasus marasca recta) grown in Zadar and Split area were determined. Total and soluble dry matter increased and pH value and total acidity showed little change during ripening. The content of phenolic compounds increased during ripening as well as content of anthocyanins, while antioxidant activity decreased with ripening. That indicates there was no correlation between antioxidant activity and content of total phenolic compounds

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

Influence of laccase and polyvinylpyrrolidone on the quality and phenolic composition of Laški Riesling wine

Fenolni spojevi su poželjan sastojak vina zbog njihovog dobro poznatog pozitivnog učinka na zdravlje ljudi, međutim zbog podložnosti oksidaciji, mogu negativno utjecati na boju, stabilnost te ukupnu kvalitetu bijelih vina. Sumporni dioksid, učinkovit antioksidans koji se koristi za stabilizaciju i sprječavanje posmeđivanja, izbjegava se zbog mogućeg štetnog utjecaja na zdravlje ljudi i kvalitetu vina. Stoga se koriste i istražuju druga sredstva kao npr. polivinilpolipirolidon (PVPP) i lakaza. PVPP je sintetski polimer koji veže fenolne spojeve i time sprječava njihovu oksidaciju. Nasuprot tome, enzim lakaza katalizira oksidaciju fenolnih spojeva te ubrzava nastajanje visokomolekularnih smeđe obojenih polimera koji se uklanjaju odgovarajućim postupcima filtracije vina. Na taj način se sprječava naknadna oksidacija fenolnih spojeva te posmeđivanje i zamućenje vina. S tim u vezi cilj istraživanja bio je ispitati utjecaj tretmana PVPP-om ili lakazom na fizikalno-kemijska svojstva (udjeli etanola, ukupnog ekstrakta, hlapljivih i nehlapljivih kiselina, pH-vrijednost, intenzitet boje), senzorsku kvalitetu i koncentraciju pojedinih skupina fenolnih spojeva (flavonoidi, neflavonoidi, kondenzirani tanini, leukoantocijani) bijelog vina Laški rizling. Finalizacija netretiranog (kontrolnog) vina i vina tretiranih PVPP-om odnosno lakazom provedena je ultrafiltracijom. Odabrani uvjeti tretmana, provjereni su brzim testiranjem u laboratorijskim uvjetima: aroma je u vinu ostala nepromijenjena, a masena koncentracija koloida je smanjena. Stoga su isti uvjeti tretmana primijenjeni u industrijskom mjerilu te uglavnom nisu značajno utjecali na fizikalno-kemijska svojstva, a poboljšali su senzorsku kvalitetu tretiranih vina. Smanjili su koncentracije svih skupina fenolnih spojeva i rezultirali manjim intenzitetom boje tj. svjetlijom bojom tretiranih od kontrolnog vina. Dobiveni rezultati ukazuju na prikladnost PVPP-a i lakaze u postupcima očuvanja boje i kvalitete bijelog vina Laški rizling.Phenolic compounds, with their well known positive effect on human health, are a desirable constituent of wine, however, due to their susceptibility to oxidation, they can negatively affect the color, stability and overall quality of white wines. Sulphur dioxide, the effective antioxidant used for wine browning prevention and stabilization, is avoided cause of possible harmful effect on human health and wine quality. Therefore, other agents such as polyvinylpolypyrrolidone (PVPP) and laccase are used, and investigated as well still , too. PVPP ( a synthetic polymer) binds phenolic compounds and thus prevents their oxidation. In contrast, the enzyme lacase catalyzes the oxidation of phenolic compounds and accelerates the formation of high molecular weight brown polymers which are removed in finalization processes such as ultrafiltration. In this way, the subsequent oxidation of phenolic compounds as well as wine browning and turbidity are prevented. Considering the above facts, the aim of this study was to examine the effectiveness of treatment with PVPP or laccase, combined with ultrafiltration, on the physicochemical properties (contents of ethanol, total extract, volatile and non-volatile acids, pH value, color intensity), sensory quality and the concentration of individual groups of phenolic compounds (flavonoids, neflavonoids, condensed tannins, leukoanthocyanidins) of Laški Riesling white wine. Finalization of untreated (control) wine and wines treated with PVPP or laccase and treated wines was performed by ultrafiltration. The selected experimental conditions were previously tested in laboratory scale and confirmed that colloid content was reduced by treatments with PVPP or laccase. while wine aroma was not significantly impaired. Further, the same treatments were applied in the industrial conditions and according to obtained results they did not significantly affect the basic physicochemical properties, but improved the sensory quality of the treated wines. Therefore, the same treatment conditions were applied in industrial scale and generally did not significantly affect the physico-chemical properties, while the sensory quality of the treated wines were improved. The concentrations of all groups of phenolic compounds and color intensities were reduced in the treated wines when compared to color control wine. The obtained results indicate the suitability of both PVPP and laccase in the processes of stabilization and color preservation of white wine Laški Riesling

Color Parameters and Total Anthocyanins of Sour Cherries (Prunus cerasus L.) During Ripening

Color is very important indicator of quality of fresh fruit. It also serves for estimating the stage of maturity of fruit. Plant pigments responsible for the color of some kind of fruits are anthocyanins. Anthocyanins are the flavonoids which are present in high amounts in sour cherries. The aim of this study was to determine total anthocyanins and color parameters of sour cherries ‘Cigančica’ and ‘Keleris’ collected in Osijek and Zadar (Croatia) in 2005 during ripening. Color parameters of skin and fl esh of sour cherries were determined with colorimetric CIE LAB method and total anthocyanins were determined by means of high performance liquid chromatography (HPLC) using UV/VIS PDA detector. Total anthocyanin was higher in sour cherries cv. Keleris grown in Zadar than in cv. Cigančica grown in Osijek during ripening although cv. Keleris is light colored genotype. Obtained results suggested that warm Mediterranean climate could have influence on high anthocyanin synthesis during ripening. Analysis of variance showed that stage of ripening did not influence total anthocyanin concentrations, but influenced almost all color parameters. Parameter H° was good indicator of color variation during ripening in both sour cherry cultivars