Elsevier

Food and Chemical Toxicology

Volume 45, Issue 12, December 2007, Pages 2574-2580
Food and Chemical Toxicology

Phenolic content and antioxidant activities of white and purple juices manufactured with organically- or conventionally-produced grapes

https://doi.org/10.1016/j.fct.2007.06.022Get rights and content

Abstract

Although the beneficial effects of moderate wine intake are well-known, data on antioxidant capacity of grape juices are scarce and controversial. The purpose of this study was to quantify total polyphenols, anthocyanins, resveratrol, catechin, epicatechin, procyanidins, and ascorbic acid contents in grape juices, and to assess their possible antioxidant activity. Eight Vitis labrusca juices – white or purple, from organically- or conventionally-grown grapes, and obtained in pilot or commercial scale – were used. Organic grape juices showed statistically different (p < 0.05) higher values of total polyphenols and resveratrol as compared conventional grape juices. Purple juices presented higher total polyphenol content and in vitro antioxidant activity as compared to white juices, and this activity was positively correlated (r = 0.680; p < 0.01) with total polyphenol content. These results indicate that white and purple grape juices can be used as antioxidants and nutritional sources.

Introduction

Experimental data have increasingly suggested that cellular oxidative damage induced by reactive species (RS) has a relevant pathophysiological role in several types of human diseases, such as atherosclerosis and cancer (Ames et al., 1993). In order to neutralize these RS, our cells have developed a complex biochemical redox mechanism, consisting of both enzymatic and non-enzymatic components (Park et al., 2003). Moreover, foods, particularly fruits and vegetables, also have an important role in maintaining physiological redox equilibrium. These foods supply several antioxidants, such as vitamin C and several polyphenolic compounds, to the body. Grapes are rich in phenolic compounds, such as flavonoids (catechin, epicatechin, quercetin, anthocyanins and procyanidins), and resveratrol (3,5,4′-trihydroxy-stilbene), which are mainly found in red grape products (Wang et al., 2002, Soleas et al., 1997, Fuleki and Ricardo-da-Silva, 2003). It has been already reported that grape juice compounds can prevent: (i) platelet aggregation, (ii) LDL oxidation and oxidative damage to DNA, (iii) coronary diseases and atherosclerosis (Frankel et al., 1998, Osman et al., 1998, Day et al., 1997, Singletary et al., 2003).

As grape juices are a relevant source of polyphenolic compounds, many people are becoming aware of the importance of their consumption in their daily diet. There is an increasing public concern as to developing healthy habits and eating quality food. Some consumers are also taking into account agricultural methods (conventional or organic) when purchasing their food. Organic agriculture, among other practices, does not use pesticides during the cultivation (IFOAM, 2005). Organic strawberries and tomatoes present higher content of secondary metabolites (e.g. polyphenolic compounds), as they suffer more fungal infections, thereby producing a higher level of these metabolites for their defense (Asami et al., 2003, Lombardi-Boccia et al., 2004). To our knowledge, there are no studies in literature on how organic cultivation of grapes may change the chemical characteristics of grapes and their products (wine and juices). In addition, we did not find any studies comparing the biological activities of organic and conventional, white and purple grape juices.

This study aimed at assessing the antioxidant capacity of different types of grape juices (white or purple juices from organically- or conventionally-grown grapes) using standard in vitro and ex vivo assays. In addition, (+)-catechin, (−)-epicatechin, trans-resveratrol, anthocyanidin, and individual procyanidin contents of juices produced from different Vitis labrusca varieties were analyzed by HPLC.

Section snippets

Chemicals

DPPHradical dot, trans-resveratrol, (+)-catechin, (−)-epicatechin, gallic acid, and procyanidins B1, B2, B3 and B4 were obtained from Sigma–Aldrich (St. Louis, MO). The anthocyanin pigments cyanidin-3-glucoside, delphinidin-3-glucoside, peonidin-3-glucoside, and malvidin-3-glucoside were obtained from Extrasynthese (Gennay, France). Methyl-parathion was obtained from Bayer, and the acetylcolinesterase kit was purchased from UFRJ (Rio de Janeiro, Brazil). All other chemicals were purchased from E. Merck

Grape juice chemical analysis and nutritional evaluation

Grape juice alcohol levels were between 0.03% and 0.3% (v/v), with total acidity between 0.40 and 0.96 g/100 mL tartaric acid. No volatile acidity was detected in any juice. pH values varied from 3.21 to 3.60, and sulfur dioxide from 0.027 to 0.029 g/L. Table 2 shows nutritional analyses and ascorbic acid content. Juices produced at pilot scale presented the highest calorie value and carbohydrate content. Purple grape juices had high vitamin C (ascorbic acid) levels. Except for the purple grape

Grape juice phenolic compounds, vitamin C, and nutritional analyses

Phenolic compounds are secondary metabolites produced and accumulated in plant tissues. Changes in phytopathogenesis, among others factors, may result in different concentrations of these compounds in plant organs. Organic farming is currently practiced world wide, and does not use chemical substances, such as pesticides and synthetic fertilizers, for growing crops. As pesticides are not used, plants are more susceptible to the action of phytopathogens, and this causes the plant to produce

Acknowledgments

We thank University of Caxias do Sul (Caxias do Sul, Rio Grande do Sul, Brazil), CAPES, IBRAVIN, CNPq, and FAPERGS for their help and financial support during this research study.

References (33)

  • J.V. Bannister et al.

    Assays for SOD

    Methods Biochem. Analyt.

    (1987)
  • A.D. Barata Soares et al.

    Ascorbic acid biosynthesis: a precursor study on plants

    Braz. J. Plant Physiol.

    (2004)
  • V.L.F.C. Bastos et al.

    Brain acetylcholinesterase as in vitro detector of organophosphorus and carbamate insecticides in water

    Water Res.

    (1991)
  • M. Carbonaro et al.

    Modulation of antioxidant compounds in organic vs. conventional fruit (Peach, Prunus persica L., and Pear, Pyrus commumis L.)

    J. Agric. Food Chem.

    (2002)
  • A.P. Day et al.

    Effect of concentrated red grape juice consumption on serum antioxidant capacity and low-density lipoprotein oxidation

    Ann. Nutr. Metab.

    (1997)
  • I. Durak et al.

    Comparison of antioxidant potentials of red wine, white wine, grape juice and alcohol

    Curr. Med. Res. Opin.

    (1999)
  • Cited by (200)

    • Wine lees: From waste to O/W emulsion stabilizer

      2021, Innovative Food Science and Emerging Technologies
    • Pharmacotherapeutic potential of Vitis vinifera (grape) in age-related neurological diseases

      2024, Boletin Latinoamericano y del Caribe de Plantas Medicinales y Aromaticas
    View all citing articles on Scopus
    View full text