Evaluation of commercial red fruit juice concentrates as ingredients for antioxidant functional juices

Phenolic profiles of nine red fruit commercial juice concentrates were characterised by means of high -performance liquid chromatography–diode array detection–mass spectrometry–mass spectrometry. Flavonoids such as anthocyanins, flavonols, hydroxycinnamic acid derivatives, stilbenoids, flavan 3-ols, ellagic acid derivatives, and other phenolic acids, were both identified and quantified in chokeberry, elderberry, blackcurrant and redcurrant, strawberry, red grape, cherry, plum, and raspberry commercial juice concentrates. Once the characterisation was carried out, the antioxidant capacity of each concentrate was assessed in vitro by means of two different methods: the 2,2-azinobis(3-ethylbenzthiazoline-6-sulfonic acid) (Trolox equivalent antioxidant capacity) method and the 2,2-diphenyl-1-picrylhydrazyl radical method. Elderberry, chokeberry and blackcurrant concentrates were the richest in total phenolics and they had the strongest antioxidant capacity; therefore, these three juices may have huge interest as ingredients in the design of functional juices.     

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.     

Vitamin C,vitamin A,phenolic compounds and total antioxidant capacity of new fruit juice and skim milk mixture beverages marketed in Spain

The growing interest in new functional foods with special characteristics and health properties has led to the development of new beverages based on fruit juice–skim milk mixtures. The proliferation of ready-to-drink beverages has caused the market to focus its interest on these products. Commercial conventionally pasteurized or sterilized beverages based on a mixture of fruit juice and skim milk were evaluated nutritionally for their concentrations of vitamin C, vitamin A and phenolic compounds and their total antioxidant capacity, taking the influence of physicochemical parameters into account. The main contribution to the total antioxidant capacity (TEAC, trolox equivalent antioxidant capacity) was provided by vitamin C, followed by phenolic compounds, in accordance with a mathematical equation obtained from the data: TEAC = −0.184 + 0.009 ∗ [vitamin A] + 0.011 ∗ [phenolic compounds] + 0.058 ∗ [vitamin C]. The R-squared value was 86.88%. Citrus fruits, such as lemons or oranges, were the fruits associated with the greatest antioxidant capacity in the samples analysed.     

The effect of enzymatic treatment on blackcurrant (Ribes nigrum) juice flavour and its stability

The effects of different enzymatic treatments on the sensory profile and chemical composition, especially various phenolic compounds, sugars and fruit acids, of blackcurrant juices were investigated. In addition to pectinolytic activities, the enzymes had different cellulolytic, hemicellulolytic and glycolytic activities. The enzymatic treatments improved significantly the yield of juice, but with more fermented and astringent characteristics than juices without enzymatic hydrolysis. Enzymes with higher glycosidase activity increased astringency and the content of phenolic compounds in the juice. When the incubation temperature was elevated the contents of fruit acids increased whereas sugars and the perceived sweetness were the highest in the juices without enzymatic treatments. Despite of the significant changes in chemical composition, the sensory properties did not change significantly during 6 weeks of storage. Optimisation of the enzymatic process is crucial for juice making as maximising the juice yield or the content of phenolic compounds may produce unwanted sensory properties to the juice.     

Effect of commercial mannoproteins on wine colour and tannins stability

Commercial oenological products containing mannoproteins have the purpose of preventing tartrate salts precipitation or achieving wines with a better mouth-feeling. The evaluation of the influence of three commercial mannoproteins on colour and tannin stability of three different red wines (two from Touriga Nacional and one from Alfrocheiro and Aragonês varieties) was studied. The evolution of colour through time was similar for all modalities, resulting in an increase of polymeric pigments and colour hue and a decrease of other parameters, suggesting that there was no influence of commercial mannoproteins on colour stability. The tannin profile evolution showed a possible stabilizing effect of one of the commercial products for tannins with an mDP between 8 and 14. It is possible that the commercial mannoproteins used in this work have some influence on the tannin aggregation evolution, contributing to the delay of tannin polymerisation in red wines.     

Sensory quality and compositional characteristics of blackcurrant juices produced by different processes

Effects of enzymatic and non-enzymatic juice pressing on key orosensory and chemical quality factors of blackcurrant juices were studied in laboratory scale using berries of five different cultivars (Mortti, Mikael, Marski, Ola and Breed15). Enzymatic processing increased the juice yield by 10–22% and the content of various phenolic compounds in juice by 4–10-fold as compared to the non-enzymatic process. Higher intensity of the mouth-drying astringency of the enzyme-aided juice was the most significant orosensory difference between the processes. Juices of different blackcurrant cultivars varied in sweetness, sourness and bitterness. The most intensive sensory attributes of the juices were sourness and puckering astringency regardless of processing method. They correlated positively with each other and were contributed by acid content and pH. In enzyme-aided juices, the contents of flavonol glycosides and hydroxycinnamic acids were associated with mouth-drying astringency, and sugar/acid ratio correlated with sweetness. These correlations were less clear in non-enzyme juices possibly due to lower content of phenolic compounds and the high content of pectin.     

Main characteristics of peanut skin and its role for the preservation of meat products

BackgroundThe produced peanuts by-products are a huge challenge, but they are recognized to be a source of valuable nutrients, including natural antioxidants and antimicrobials. Antioxidants are considered as necessary ingredients in food to prevent oxidative reactions and their undesirable effects in food quality during processing and storage. However, the use of such compounds is regulated due to their harmful effects revealed by in vitro and in vivo studies. The use of natural antioxidants appears as an interesting alternative for food producers, particularly meat industries.Scope and approachPeanut skin (PS), a by-product of peanut processing in agro-industries, constitutes an under-explored source of natural antioxidants. Thus, this review was focused on both the reuse of peanuts by-products and societal health, reducing the use of synthetic antioxidants and antimicrobials.Key findings and conclusionsProanthocyanidins are the main compounds in PS that are associated with the antioxidant activity in vitro and its protective effect in meat products. Studies in recent literature strengthen the role of PS as a natural source of antioxidants wherein oxidative reactions involving mainly pigments, lipids and proteins are delayed.     

蓝靛果汁维生素C热降解动力学的研究

以新榨蓝靛果汁为试材,采用控制温度、避光、连续充氮气等方法探讨蓝靛果汁维生素C的热降解动力学,为深加工条件的优化控制及保质期的预测提供科学的依据。结果表明:蓝靛果维生素C对热不稳定,维生素C的降解过程符合一级动力学反应;通过蓝靛果汁维生素C的热降解速率常数和活化能(Ea)分析,结果表明:充氮气处理可以提高蓝靛果维生素C的稳定性,光照对蓝靛果汁维生素C降解的影响比氧气对蓝靛果汁维生素C降解的影响大。     

Effects of processing on anthocyanins,carotenoids and vitamin C in summer fruits and vegetables

The purpose of this study was to evaluate the effects of processing, i.e. heating (98 °C, 10 min), freezing (−20 °C) and freeze-drying on anthocyanins, carotenoids, and vitamin C in summer fruits and vegetables, i.e. cherries, nectarines, apricots, peaches, plums, carrots and red bell peppers. The commodities were collected from growers located in the Otago region (namely Cromwell, Roxburgh, Mosgiel and Clinton), New Zealand. The results revealed that each commodity contained different contents of phytochemicals. The content and the process stability of phytochemicals in each commodity were influenced by the geographical location of the growers. In general, a high content of phytochemicals was found in summer fruits and vegetables grown in Otago compared to those grown in the Northern Hemisphere, e.g. anthocyanins in cherries, nectarines, peaches and plums; total carotenoids in red bell peppers and nectarines and vitamin C in cherries, peaches, red bell peppers and carrots. Heating and freezing enhanced the release of membrane bound anthocyanins, resulting in higher content after processing compared to fresh commodities. In the commodities studied, with the exception of red bell peppers, the stability of ascorbic acid was increased if ascorbic acid oxidase was inactivated for example by heating.     

橙汁饮料中维生素C动态吸氧的研究

为了更好地研究饮料中维生素C有氧降解机理,以橙汁饮料,在一定温度下构成流通环境,通过促使维生素C有氧降解的方法,得到橙汁饮料中维生素C在流通环境下的降解情况。研究结果表明,维生素C的降解符合一级反应模型,溶液中的溶解氧在前3d急剧增加,之后趋于平稳,同时还得到了在有顶空气体存在的情况下,橙汁溶液中溶解氧浓度和气体中氧气浓度的变化关系,在一定温度下两者符合线性规律。     

Polyphenol composition of peel and pulp of two Italian fresh fig fruits cultivars (<Emphasis Type="Italic">Ficus carica</Emphasis> L.)

An analytical study was carried out on phenols in two fig cultivars (Ficus carica L.), one black and one green. Fresh fruits were peeled and phenols were extracted separately from the peel and the pulp. The extracts were subjected to HPLC-DAD analysis, by monitoring at four wavelengths, 280, 316, 365 and 520 nm for catechins and benzoic acids, hydroxycinnamic acids, flavonols and anthocyanins, respectively. Results showed that phenols are concentrated almost exclusively in the peel, with the black cultivar having the highest content. In particular, the peel was rich in rutin, with amounts from 527 to 1,071 mg/kg (fresh basis) for green and black figs, respectively. The peel of black figs showed an appreciable content of cyanidin 3-O-rutinoside. The pulp of both green and black cultivars contained only cyanidin 3-O-rutinoside, while the cyanidin 3-O-glucoside was found only in the peel of the black figs. Chlorogenic acid and another cinnamic acid were detected in the peel of both cultivars, while benzoic acids and catechins were not present. Alessandra Del Caro and Antonio Piga contributed equally to this study.     

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.     

赤藓糖醇对柠檬汁饮料中维生素C保护作用的研究

本文以柠檬汁饮料作为实验材料,采用调节温度的方法对维生素C的热降解进行动力学研究。在建立动力学模型的基础上,通过速率常数、反应活化能等动力学参数,来探究柠檬汁饮料中赤藓糖醇的加入对维生素C的保护作用。研究结果表明:柠檬汁饮料在贮藏过程中,维生素C对热不稳定,其热力学降解符合一级反应动力学模型;在本次实验中,1%~3%赤藓糖醇浓度的加入均有助于减缓维生素C的降解速率。其中,当赤藓糖醇添加浓度为2%时,维生素C降解反应活化能达到最大,为75.47kJ/mol,比对照高出了9.79kJ/mol。因此,赤藓糖醇在一定程度上能够起到对维生素C的保护作用。      

Influence of ultra-high pressure homogenisation on antioxidant capacity,polyphenol and vitamin content of clear apple juice

Ultra-high pressure homogenisation (UHPH) is a recently developed technology and is still under study to evaluate its effect on different aspects of its application to food products. The aim of this research work was to evaluate the effect of UHPH treatments on quality characteristics of apple juice such as antioxidant capacity, polyphenol composition, vitamin C and provitamin A contents, in comparison with raw (R) and pasteurised (PA) apple juice. Several UHPH treatments that include combinations of pressure (100, 200 and 300 MPa) and inlet temperatures (4 and 20 °C) were assayed. Apple juice was pasteurised at 90 °C for 4 min. Antioxidant capacity was analysed using the oxygen radical antioxidant capacity (ORAC), 2,2-diphenyl-1-picrylhydrazyl (DPPH), trolox equivalent antioxidant capacity (TEAC), ferric reducing antioxidant power (FRAP) assay while total phenolic content was determined by the Folin–Ciocalteau assay. According to the FRAP and DPPH assays, UHPH processing did not change apple juice antioxidant capacity. However, significant differences were detected between samples analysed by TEAC and ORAC assays. In spite of these differences, high correlation values were found between the four antioxidant capacity assays, and also with total polyphenol content. The analysis and quantification of individual phenols by HPLC/DAD analytical technique reflects that UHPH-treatment prevented degradation of these compounds. Vitamin C concentrations did not change in UHPH treated samples, retaining the same value as in raw juice. However, significant losses were observed for provitamin A content, but lower than in PA samples.     

Flavonoids in Gran Negro berries collected from shoulders and tips within the cluster,and comparison with Brancellao and Mouratón varieties

Galicia (the north-western corner of Spain) is a Spanish region with several old-traditional winegrowing areas. Vitis vinifera L. cv. Mencía is one of the most often used to produce quality red wines but the tendency of the world wine-making market is to reward the production of wines that have particular and differentiated characteristics. In Galicia, there are other red cultivars such as Gran Negro which were not exploited for their potential to produce quality red wines. Dynamics of anthocyanin and flavonol accumulation in Gran Negro berries were studied separately in two different positions within the cluster (tips and shoulders) during 30 days before harvest to assess the existence of different polyphenol quality in both positions and as a consequence, red wines with different qualities. Dynamics of anthocyanins over ripening confirmed that anthocyanins presented upward trends (from 1510 to 1727 mg/kg in tips; and from 1532 to 1728 mg/kg in shoulders) but dynamics of flavonols confirmed that maximum values were reached and stabilised thirty days before harvest (from 45 to 39 mg/kg in tips; and from 49 to 45 mg/kg in shoulders). No differences were observed in anthocyanin and flavonol contents collected from tips and shoulders which indicates that is not necessary to harvest them separately. The results from Gran Negro were compared with those of Brancellao and Mouratón.     

Polyphenol composition, vitamin C content and antioxidant capacity of Mauritian citrus fruit pulps

The pulp extracts of twenty-one varieties of citrus fruits (oranges, satsumah, clementine, mandarins, tangor, bergamot, lemon, tangelos, kumquat, calamondin and pamplemousses), commonly grown in Mauritius, were characterised in terms of their total soluble solids (TSS), titratable acidity (TA), polyphenol composition and vitamin C contents. Total phenolics ranged from 406.3 ± 14 to 1694 ± 19 ??g g^− 1 fresh weight (FW). Total flavonoids varied between 133 ± 6 and 965 ± 7 ??g g^− 1 FW and vitamin C contents were from 166 ± 19 ??g/mL to 677 ± 22 ??g/mL. The pulp of a pamplemousse variety had the highest TSS/TA ratio whereas lemon pulps had lowest TSS/TA ratios. The antioxidant activities of the pulp extracts were assessed and total phenolics correlated strongly with the trolox equivalent antioxidant capacity (TEAC), ferric reducing antioxidant capacity (FRAP) and hypochlorous acid (HOCl) scavenging activity assays. Based on their antioxidant activities, nine citrus fruits namely, one orange, tangor, kumquat, calamondin and pamplemousse variety and two mandarin and tangelo varieties were further characterised for their flavanone, flavonol and flavone levels by HPLC. Hesperidin (6.89 ± 0.06 to 26.98 ± 0.07 mg/g FW) and narirutin (0.27 ± 0.01 and 20.91 ± 0.10 mg/g FW) were present at high concentrations compared to the other flavonoid glycosides in the pulp extracts. Naringin was detected only in pulp extracts of pamplemousses. In the light of the data obtained, citrus fruit pulps represent an important source of phytochemicals with potent antioxidant capacity.     

Determination of the degradation kinetics of anthocyanins in a model juice system using isothermal and non-isothermal methods

The effect of temperature on the degradation of blackcurrant anthocyanins in a model juice system was determined over a temperature range of 4–140 °C. The thermal degradation of anthocyanins followed pseudo first-order kinetics. From 4–100 °C an isothermal method was used to determine the kinetic parameters. In order to mimic the temperature profile in retort systems, a non-isothermal method was applied to determine the kinetic parameters in the model juice over the temperature range 110–140 °C. The results from both isothermal and non-isothermal methods fit well together, indicating that the non-isothermal procedure is a reliable mathematical method to determine the kinetics of anthocyanin degradation. The reaction rate constant (k) increased from 0.16 (±0.01) × 10⁻³ to 9.954 (±0.004) h⁻¹ at 4 and 140 °C, respectively. The temperature dependence of the rate of anthocyanin degradation was modelled by an extension of the Arrhenius equation, which showed a linear increase in the activation energy with temperature.