Phenolic acids, flavonoids, vitamin C and antioxidant capacity of strawberry juices processed by high-intensity pulsed electric fields or heat treatments

The effect of high-intensity pulsed electric fields (HIPEF) processing (35 kV/cm for 1,700 μs in bipolar 4-μs pulses at 100 Hz) on individual phenolic compounds (phenolic acids and flavonoids), vitamin C and antioxidant capacity of strawberry juice was evaluated and compared to heat (90 °C for 60 or 30 s) and fresh juice as a reference. Although strawberry juice underwent a substantial depletion of health-related compounds with storage time irrespective of the treatment conducted, ellagic acid was enhanced. HIPEF-treated strawberry juice maintained higher amounts of phenolic acids (ellagic and p-coumaric acid) and total anthocyanins than the thermally treated juices during the storage period. Regarding the antioxidant capacity, similar DPPH and ABTS values were obtained so that differences among pasteurized juices were non significant. HIPEF processing may be a technology as effective as thermal treatments not only to achieve safe and stable juices, but also to obtain juices with a high content of antioxidant compounds.     

The effect of addition of chokeberry, flowering quince fruits and rhubarb juice to strawberry jams on their polyphenol content, antioxidant activity and colour

The aim of the study was to establish whether the addition of berries (flowering quince, chokeberry) and rhubarb juice during jam processing improves its colour and enriches jams in polyphenol compounds other than those found in strawberries. The sum of phenolic compounds determined by HPLC was distributed in a wide concentration range depending on the cultivar. Jams prepared from Elkat cultivar had 27% more total phenolic compounds than jams prepared from Senga Sengana. The following compounds were identified in jams prepared from strawberries: p-coumaric, ferulic and ellagic acids, quercetin, kaempferol, anthocyanins, (+)-catechin, (−)-epicatechin and proanthocyanidins. Proanthocyanidins and ellagic acid are the major polyphenol compounds of all strawberries jams. The Elkat cultivar (47.34 mg/100 g) contained higher amounts of proanthocyanidins compared to Senga Sengana (29.95 mg/100 g). The addition of 10% of flowering quince and chokeberry to jams during their preparation resulted in the increase in the content of phenolic components in final products, especially for proanthocyanidins. The highest level of total polyphenols (P < 0.05) was found in strawberry mixed with chokeberry, 237.82 mg/100 g for Senga Sengana and 260.61 mg/100 g for Elkat. There has been a marked increase of proanthocyanidins content (5.4 and 4.0 times) in jams made from Senga Sengana and Elkat cultivars mixed with chokeberry. However, the addition of rhubarb juice did not increase the content of polyphenol in Senga Sengana jam (not statistically significant). Antioxidant activity of strawberry jam was determined by 2,2′azinobis-(3-ethylbenzthiazoline-6-sulphonic acid (ABTS), 1,1-Diphenyl-2-picrylhydrazyl radical (DPPH) and ferric reducing/antioxidant power methods (FRAP). The antioxidant activity of this mixed jam was more than two times higher (P < 0.05) than control sample of strawberry jam. Rhubarb juice had high effect on L* (lightness) value in case of all strawberry varieties. The redness (a*), and yellowness (b*) were significantly different in jams with supplement. Strawberry jam with chokeberries had smaller L* value than control and other samples, and the lowest a* and b* values. This variation could be due to the nature of the pigments in these fruit cultivars and the content of anthocyanins which resulted in more reddish colour.     

Determination of phenolic composition and antioxidant capacity of blood orange juices obtained from cvs. Moro and Sanguinello (Citrus sinensis (L.) Osbeck) grown in Turkey

The phenolic compounds and antioxidant capacities of orange juices obtained from cvs. Moro and Sanguinello (Citrus sinensis (L.) Osbeck) were determined. A high-performance liquid chromatographic method coupled with diode-array detection was used to identify and quantify phenolic compounds of the orange juices. A total of 18 phenolic compounds were identified and quantified in Moro and Sanguinello orange juices, including hydroxybenzoic acids (2), hydroxycinnamic acids (5), flavanones (5), and anthocyanins (6). It was observed that total phenolic content of Moro juice was higher than that of Sanguinello juice. Ferulic acid was the most dominant hydroxycinnamic acid and cyanidin 3-(6″-malonyl glucoside) and cyanidin 3-glucoside were the most dominant anthocyanins in both cultivars. Antioxidant activities of orange juices were measured using the DPPH^· (2,2-diphenyl-1-picrylhydrazyl) method. According to DPPH^· assays, the antioxidant capacity of Moro juice was found to be higher than that of Sanguinello juice.     

Effect of cultivar and fruit storage on basic composition of clear and cloudy pear juices

BackgroundPears due to low acidity are a suitable raw material for the production of multifruit nectars thus it is justified to determine the chemical composition and investigate the effect of cultivar and fruit maturity on juices quality.MethodsJuices from ‘Alexander Lucas’ and ‘Conference’ cultivars were produced after harvest and after 3 months of pears storage.ResultsAverage yield of clear juices was 76.4% for ‘Conference’ cultivar and 74.3% for ‘Alexander Lucas’. In the case of cloudy juices, the yield was lower by about 3%. Processing of ‘Conference’ cv. from stored fruit resulted in yield decrease compared to fruits after harvest; this was not in case of ‘Alexander Lucas’ in 2008, where juices produced from stored fruits were characterized by a higher yield compared to fresh fruit.Total solids content in clear juices was 125–135 g/L and 135–141 g/L for cloudy juices. ABTS^●+ and total phenolics analysis showed that cloudy juices were characterized by a higher antioxidant activity and phenolics content than the clear ones.ConclusionPear storage, on the contrary to apples, does not decrease their suitability for cloudy juice production. Cloudy juices as a rule have higher antioxidant activity than the clear ones.     

Changes of peach juices during the shelf-life and their in vitro effect on glycolipid digestion and neurotransmitter metabolism

In this study, the polyphenols content, α-amylase, α-glucosidase and cholinesterase-inhibiting activities of cloudy peach (Prunus persica) juices, were measured immediately after thermal treatment and after storage (6 months at 4 and 30 °C). The study showed that some cultivars were more useable for industry than others. Due to the high content of polyphenols and a high ability to inhibit enzymes linked to type 2 diabetes and Alzheimer's disease, noteworthy are the juices obtained from ‘Redheaven early’ and ‘Redheaven’ cultivars. The content of total phenolics ranged from 1109.7 to 390.7 mg/L of juice, and the dominant fraction was polymeric procyanidins. Following 6 months of storage a significant change was observed in the content of polyphenols, especially flavonols and anthocyanins. The data compiled from the conducted study indicate that peach juice could be useful for the juice industry as a promising source of bioactive compounds.     

Effect of thermal treatments on phytochemicals in conventionally and organically grown berries

BACKGROUND: Consumer demand for organic foods is increasing despite a lack of conclusive evidence of nutritional superiority of organically grown produce. The objective of this investigation was to evaluate the effects of thermal treatments on phytochemicals in conventionally and organically grown berries. Two cultivars of conventionally and organically grown red raspberries and blueberries were analysed for total anthocyanins, total and specific phenolic compounds and total antioxidant activity. Fresh berries were thermally processed into cans and juice/puree with and without blanching, and the changes in phytochemicals were monitored. RESULTS: Total anthocyanin and phenolic contents of berries were not influenced by the agricultural production system. Total antioxidant activity of berries was also not influenced by the production system, but antioxidant activity varied significantly between cultivars. After canning, total anthocyanins decreased by up to 44%, while phenolic contents and antioxidant activity of both berries generally increased by up to 50 and 53% respectively. The level of changes in phytochemicals during berry puree/juice processing was influenced by blanching and type of berries. CONCLUSION: Phenolic contents and antioxidant activities of berries increased while total anthocyanins decreased during canning. Blanching prior to puree/juice processing improved the retention of phytochemicals in blueberries. Copyright © 2010 Society of Chemical Industry     

Effect of pectinase treatment on extraction of antioxidant phenols from pomace,for the production of puree-enriched cloudy apple juices

Effects of pomace maceration on yield, turbidity, cloud stability, composition of phenolics, antioxidant activity and colour properties were studied, to evaluate the potential applicability of enzyme preparations in puree-enriched cloudy apple juice production. The yield of mixed juice and puree from pomace obtained in the enzymatic processing of apple ranged from 92.3% to 95.3%, significantly higher than the yield from the control without enzymatic pomace treatment (81.8%). Higher turbidity was obtained upon pomace treatment with Pectinex XXL and Pectinex Ultra SPL enzymes. The total content of phenolic compounds in apple pomace was higher than in raw juices (1520 mg/kg and 441 mg/L, respectively). The total polyphenol yields were higher in juices treated with Pectinex AFP L-4, Pectinex Yield Mash and Pectinex XXL, as compared to the control treatment. During 6 months of storage, a significant change was observed in the content of polyphenols, especially in procyanidin fractions.     

Effect of different cranberry extracts and juices during cranberry juice processing on the antiproliferative activity against two colon cancer cell lines

The effect of cranberry extracts and juices during cranberry juice processing on the antiproliferative properties against colon cancer cells was investigated. Two colon cancer cell lines HT-29 and LS-513 were treated with different concentrations of cranberry phenolic extracts from fruits, puree, depectinised puree and pomace and different concentration of three juices (raw, filtered and concentrated juices). The phenolic extracts consisted of water-soluble phenolic compounds, apolar phenolic compounds and anthocyanins. These phenolic extracts and juices were tested against two cell lines at pH 2.5 (natural juice pH) and at pH 7.0 (physiological pH). All cranberry extracts and juices could inhibit the growth of both cell lines with the IC₅₀ values (the concentration of phenolic content required to inhibit 50% the growth of cancer cells) varied from 3.8 to 179.2 μg gallic acid equivalent/ml. It was found that three types of extracts from fruit at pH 7.0 were the most effective at inhibiting the growth of HT-29 cell line. Extracts containing anthocyanins from fruit and from pomace were the most and the least efficient, respectively, in inhibiting the growth of both cancer cell lines. Further, three juices at natural pH (pH 2.5) were more effective at inhibiting the growth of two cell lines as compared to juices at pH 7.0. Concentrated juice at both pH values was the most effective at growth inhibition of two cancer cell lines compared to two other juices.     

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.     

Grape juice obtained using steam extraction and other small‐scale extraction methods: phenolic content,antioxidant capacity and stability during storage

Grape juices made using small‐scale production techniques are widely consumed. The extraction procedures employed to produce them, however, can affect bioactive compounds and antioxidant activity in the final product. In this study, juices prepared using four extraction methods (steam, extractor, juicer and blender) were evaluated for soluble and hydrolysable polyphenol content, total anthocyanin content, antioxidant capacity, physicochemical characteristics and colour. Acceptance of steam‐extracted juices and their stability during storage were also evaluated. Steam extraction resulted in a higher soluble phenolic (1073 ± 58 mg gallic acid L^?1) and anthocyanin content (138 ± 22 mg cyanidin L^?1), as well as a higher antioxidant capacity when compared to juices prepared using other methods. Although steam‐extracted juice remained microbiologically stable during 24 months of storage, changes in phytochemical compounds and antioxidant capacity did occur. Our results indicate that steam‐extracted grape juices have high commercial potential.     

Berry juices, teas, antioxidants and the prevention of atherosclerosis in hamsters

The effects of raspberry, strawberry and bilberry juices and green and black tea on early atherosclerosis in hamsters were investigated. They received an atherogenic diet and at the same time either a juice or a tea at a daily dose corresponding to the consumption of 275 ml by a 70 kg human. After 12 weeks berry juices and teas inhibited aortic lipid deposition by 79–96% and triggered reduced activity of hepatic antioxidant enzymes, not accompanied by lowered plasma cholesterol. These findings suggest that moderate consumption of berry juices and teas can help prevent the development of early atherosclerosis. There were substantial differences between the five beverages in terms of composition and concentration of individual phenolic compounds that were present. This indicates that anti-atherosclerotic effects can be induced by a diversity of phenolic compounds rather than a few specific components. The possible mechanisms by which this is brought about are discussed.     

Effects of High Hydrostatic Pressure Combined with Blanching on Microorganisms and Quality Attributes of Cloudy and Clear Strawberry Juices

Effects of high hydrostatic pressure combined with blanching on microorganisms and quality attributes of strawberry juices were investigated. High hydrostatic pressure at 600 MPa/4 min/ambient temperature inactivated total aerobic bacteria, coliform bacteria, yeasts, and molds in juices, ensuring their microbiological safety. Under this condition, the cloudiness of cloudy juices increased by 54.49% and its viscosity decreased by 12.40%. Ascorbic acid decreased by 7.82% in cloudy juices and 12.60% in clear juices. The content of total volatile flavor compounds increased by 13.21% in cloudy juices and decreased by 6.92% in clear juices. No significant changes in anthocyanins, total phenols, and antioxidant capacity were found with high hydrostatic pressure treatment.     

Effect of clouding agents on the quality of apple juice during storage

Apple pomace, (AP) was subjected to evaluation as potential source of clouding and antiradical agent in cloudy apple juice (CAJ). The evaluation was carried out in comparison with three hydrocolloids, namely sodium carboxymethyl cellulose (CMC), xanthan (XA), and pectin (P). The quality parameters of cloudy apple juice such as cloud stability, viscosity, phenolic content, sensory evaluation and antioxidant activity had been studied since these parameters control the consumer acceptance of that product. All the analyses were carried out for fresh and treated juices after storage at 4 and 25 °C for two weeks. The cloud stability of juices added decreased quickly and remained more stable than the untreated treatment. However, the hydrocolloids showed significant (P < 0.05) increase in viscosity, they exhibited deterioration in sensory attributes. The results indicated a good correlation between phenolic degradation and the radical scavenging activities.     

高静压工艺中单元操作对草莓汁饮料中抗氧化物质含量与抗氧化活性影响

研究高静压工艺中单元操作草莓浊汁饮料和清汁饮料中的主要抗氧化物质及抗氧化活性的影响。结果表明,蒸汽热烫1min使草莓中VC损失7.3%,花色苷损失18.82%,总酚含量没有明显变化,DPPH自由基清除能力和FRAP铁离子还原能力分别降低了8.14%和8.49%;离心后VC、花色苷、总酚、DPPH和FRAP分别损失50.64%、46.35%、49.34%、35.45%和39.72%;酶解对花色苷、VC和多酚含量及抗氧化活性均无显著影响;超高压处理后浊汁饮料和清汁饮料VC各降低7.8%和12.6%,但花色苷、总酚和抗氧化活性无显著变化。     

Bioactive compounds vs. organoleptic assessment of ‘smoothies’‐type products prepared from selected fruit species

The aim of this study was to determine the usability of fruits of selected species growing in Europe for the smoothies production. The organoleptic assessment, analysis of polyphenols and vitamin C content and antioxidant activity of products were determined. The panellists were most in favour of the smoothies containing cranberry, black currant and bilberry purees as well as juice from dog rose. Polymerised proanthocyanidins were found to predominate in most of the products, except for the black currant smoothies (B3) where the main group of polyphenols were anthocyanins. The content of proanthocyanidins was higher in the smoothies containing dog rose juice. The analysed products differed significantly in the content of vitamin C, as the highest content of ascorbic acid was determined in black currant smoothies with dog rose juice and bilberry puree (168.98 mg/100 g).     

Effect of jam processing and storage on total phenolics, antioxidant activity, and anthocyanins of different fruits

BACKGROUND: Fruits have been widely recognised as an excellent source of bioactive phenolic compounds. The purpose of this study was to evaluate the effect of jam processing of strawberry, cherry, apricot, fig and orange on the total phenolics, antioxidant activity and anthocyanins during 5 months of storage at 25 °C. RESULTS: Fresh strawberry had the highest contents of total phenolics (8503.1 mg GAE kg^?1) followed by cherry, apricot, fig and orange, respectively. Jam processing decreased the total phenolics, antioxidant activity, and anthocyanins of all fruits. Total phenolics of jam during storage decreased only in apricot, fig and orange. Fresh strawberry had the highest antioxidant activity (54.88% inhibition) followed by the other fruits. Antioxidant activity did not change in strawberry during jam storage, while there are reductions in the other fruits were observed. Fresh strawberry had the highest anthocyanins (2323.8 mg cya‐3‐glu kg^?1), followed by cherry and the other fruits, respectively. Results showed only a decrease of anthocyanins and pH in apricot and fig jams during 5 months of storage. CONCLUSION: Despite the reduction of these compounds in jam processing, it is considered a good method to maintain them during 5 months of storage. Copyright © 2011 Society of Chemical Industry     

Storage effects on anthocyanins, phenolics and antioxidant activity of thermally processed conventional and organic blueberries

BACKGROUND: Consumer demand for products rich in phytochemicals is increasing as a result of greater awareness of their potential health benefits. However, processed products are stored for long‐term and the phytochemicals are susceptible to degradation during storage. The objective of this study was to assess the storage effects on phytochemicals in thermally processed blueberries. Thermally processed canned berries and juice/puree were analysed for phytochemicals during their long‐term storage. RESULTS: The phytochemical retention of thermally processed blueberries during storage was not influenced by production system (conventional versus organic). During 13 months of storage, total anthocyanins, total phenolics and total antioxidant activity in canned blueberry solids decreased by up to 86, 69 and 52% respectively. In canned blueberry syrup, total anthocyanins and total antioxidant activity decreased by up to 68 and 15% respectively, while total phenolic content increased by up to 117%. Similar trends in phytochemical content were observed in juice/puree stored for 4 months. The extent of changes in phytochemicals of thermally processed blueberries during storage was significantly influenced by blanching. CONCLUSION: Long‐term storage of thermally processed blueberries had varying degrees of influence on degradation of total anthocyanins, total phenolics and total antioxidant activity. Blanching before thermal processing helped to preserve the phytochemicals during storage of blueberries. Copyright © 2011 Society of Chemical Industry     

Degradation kinetics of pigment,colour and stability of the antioxidant capacity in juice model systems from six anthocyanin sources

Coloured model juices with extracts from several species of commonly consumed vegetables rich in anthocyanins (eggplant peel, strawberry, grape, bilberry, red raspberry and plum peel) were studied in detail. The model juices prepared at pH 4.5 were stored in darkness for 17 weeks at 20 °C. The kinetics of anthocyanin degradation, colour and stability of the antioxidant capacity were measured during storage. The anthocyanins were determined identifying delphinidins, cyanidins, petunidins, pelargonidins, peonidins and malvidins. The extraction yields ranged from 2.3% to 13.3%. The level of anthocyanins in the model juices prepared with the extracts ranged between 4 and 158 mg L^–1. The results showed a good correlation between the anthocyanin concentration and the time of storage, with determination coefficients varying from R² = 0.9470 to R² = 0.9855. The eggplant peel, grape and plum peel anthocyanins showed the highest half‐life and D values that were higher than those of 12 and 17 weeks, respectively. The antioxidant capacity showed a high stability during the time of storage for all the model juices, showing the eggplant peel model juice the highest values.     

Impact of high-intensity pulsed electric fields variables on vitamin C, anthocyanins and antioxidant capacity of strawberry juice

A response surface methodology was used to determine the combined effect of HIPEF critical processing conditions on vitamin C, anthocyanins and antioxidant capacity of strawberry juice. Keeping constant the electric field strength at 35 kV/cm and the treatment time at 1000 μs, the treatments were set at frequencies from 50 to 250 Hz, pulse width from 1 to 7 μs using monopolar or bipolar mode. A second order response function covering the whole range of experimental conditions was obtained for each health-related compound. Strawberry juice antioxidant potential was affected linearly by frequency, pulse width and pulse polarity. The quadratic term of frequency and the combined effect of frequency and pulse width were also significant. HIPEF treatments conducted at 232 Hz with bipolar pulses of 1 μs led to strawberry juices with the greatest presence of health-related compounds. The evaluation of the HIPEF critical parameters influence on health-related compounds can contribute to achieve optimal processing conditions to obtain strawberry juices with high antioxidant potential.