Phenolic content and antioxidant activities of white and purple juices manufactured with organically- or conventionally-produced grapes
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
DPPH, 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)
Catalase in vitro
Methods Enzymol.
(1984)- et al.
Concentrated red grape juice exerts antioxidant, hypolipidemic, and antiinflammatory effects in both hemodialysis patients and healthy subjects
Am. J. Clin. Nutr.
(2006) - et al.
Antioxidant properties of commercial grape juices and vinegars
Food Chem.
(2005) Role of plant polyphenols in genomic stability
Mut. Res.
(2001)- et al.
Grape juice but not orange or grapefruit juice inhibits platelet activity in dogs and monkeys (Macaca fasciularis)
J. Nutr.
(1998) - et al.
Daily grape juice consumption reduces oxidative DNA damage and plasma free radical levels in healthy Koreans
Mut. Res.
(2003) - et al.
Resveratrol: a molecule whose time has come? And gone?
Clin. Biochem.
(1997) - et al.
Oxidants antioxidants, and the degenerative diseases of aging
Proc. Natl. Acad. Sci. USA
(1993) - AOAC (Association Official Agriculture Chemistry) 1998. Official methods of analysis of AOAC international, 16th...
- et al.
Comparison of the total phenolic and ascorbic acid content of freeze-dried and air-dried marionberry, strawberry, and corn grown using conventional, organic, and sustainable agricultural practices
J. Agric. Food Chem.
(2003)
Assays for SOD
Methods Biochem. Analyt.
Ascorbic acid biosynthesis: a precursor study on plants
Braz. J. Plant Physiol.
Brain acetylcholinesterase as in vitro detector of organophosphorus and carbamate insecticides in water
Water Res.
Modulation of antioxidant compounds in organic vs. conventional fruit (Peach, Prunus persica L., and Pear, Pyrus commumis L.)
J. Agric. Food Chem.
Effect of concentrated red grape juice consumption on serum antioxidant capacity and low-density lipoprotein oxidation
Ann. Nutr. Metab.
Comparison of antioxidant potentials of red wine, white wine, grape juice and alcohol
Curr. Med. Res. Opin.
Cited by (200)
Rubidium chloride doped magnesium oxide nanomaterial by using green synthesis and its characterization
2022, Chemical Physics LettersWine lees: From waste to O/W emulsion stabilizer
2021, Innovative Food Science and Emerging TechnologiesPharmacotherapeutic potential of Vitis vinifera (grape) in age-related neurological diseases
2024, Boletin Latinoamericano y del Caribe de Plantas Medicinales y Aromaticas