Total phenols, antioxidant potential and antimicrobial activity of walnut (Juglans regia L.) green husks.

CIMO/Escola Superior Agrária, Instituto Politécnico de Bragança, Campus Sta Apolónia, Apartado 1 172, 5301-855 Bragança, Portugal.
Food and Chemical Toxicology (Impact Factor: 2.61). 08/2008; 46(7):2326-31. DOI: 10.1016/j.fct.2008.03.017
Source: PubMed

ABSTRACT The total phenols content and antioxidant and antimicrobial activities were studied in walnut (Juglans regia L.) green husks aqueous extracts of five different cultivars (Franquette, Mayette, Marbot, Mellanaise and Parisienne). Total phenols content was determined by colorimetric assay and their amount ranged from 32.61 mg/g of GAE (cv. Mellanaise) to 74.08 mg/g of GAE t (cv. Franquette). The antioxidant capacity of aqueous extracts was assessed through reducing power assay, scavenging effects on DPPH (2,2-diphenyl-1-picrylhydrazyl) radicals and beta-carotene linoleate model system. A concentration-dependent antioxidative capacity was verified in reducing power and DPPH assays, with EC50 values lower than 1 mg/mL for all the tested extracts. The antimicrobial capacity was screened against Gram positive and Gram negative bacteria, and fungi. All the extracts inhibited the growth of Gram positive bacteria, being Staphylococcus aureus the most susceptible one with MIC of 0.1 mg/mL for all the extracts. The results obtained indicate that walnut green husks may become important in the obtainment of a noticeable source of compounds with health protective potential and antimicrobial activity.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Iranian walnut shows genetic diversity and has a large distribution. Different species of these walnuts have many variations in genes resistant to dryness, diseases, pests and other factors. In order to compare the reducing power and radical scavenging activities of Iranian walnut hull and shell phenolic extracts, seven different cultivars (Duclouxiana, Fallax, Orientis, Mayette, Fernor, Mellanaise and Elit) were selected from Barandoz, Khaletabad, Jamalabad, Kahriz, Gaznagh, Ziva and Nazlo, West Azerbaijan province, Iran, in 2010. The fruits of these walnuts were collected, their hulls and shells were dried and ground, and then methanolic extracts were prepared from these hulls and shells. Total phenolic content was determined using the Folin-Ciocalteu (F–C) method. The extracts' reducing power and scavenging capacity for radical nitrite, hydrogen peroxide and superoxide were evaluated. The results show that the antioxidant and antiradical activities of the walnut hull are higher than those of its shell phenolic extract among different cultivars of walnut. In addition, the reducing power of walnut hull and shell phenolic extract was positively correlated with the phenolic content and radical scavenging capacities of walnut hull and shell extracts were positively correlated with phenolic content and reducing power in different cultivars.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Agro-industrial wastes are rich in bioactive compounds. Its use as a source of natural antimicrobials may provide alternatives to the food industry as it enables the replacement of synthetic preservatives by natural compounds, as well as the disposal of by-products and reduced environmental impact. Therefore, this study assessed the antimicrobial potential and chemical composition of agro-industrial wastes against pathogenic microorganisms of importance in foods. Beet stalk, peanut peel, Pinot Noir grape marc, Petit Verdot grape seed and marc, red grapes fermentation lees and guava bagasse wastes showed antimicrobial activity against Staphylococcus aureus and Listeria monocytogenes. The minimum inhibitory concentrations ranged from 0.78 to 25mg/ml. Wastes with antimicrobial activity showed the highest total phenolic compounds among the wastes studied (37.3 to 400.2g GAE/kg). Analyses by GC-MS allowed the identification of caffeic, gallic, ferulic and ρ-coumaric acids, besides flavonoids quercetin, myricetin and epicatechin on wastes that exhibited antimicrobial activity. This study demonstrates that agro-industrial wastes from wine and food processing industries could be used as source of research on new antimicrobial compounds for use by food and beverage industry as natural preservatives. INTRODUCTION The use of antimicrobials in food has become increasingly necessary as the global economy boosts the production and transportation of food worldwide; however, to ensure the supply of high-quality food, the use of preservatives is essential (Davidson and Branen, 2005). The potential application of natural antimicrobial compounds by the food industry is huge, and studies on the incorporation of antimicrobials in food and to maximize their biofunctionality have been conducted worldwide (Naidu, 2000). Studies have shown the presence of bioactive compounds in different types of agro-industrial wastes, representing valuable potential application in industry. Their reuse would reduce environmental risks caused by disposal, besides providing a source of profitability for populations living around industrial regions (Anastasiadi, et al., 2008). Different types of waste can be used as a source of raw material in researches for natural antimicrobials. Studies have found bioactive compounds with antimicrobial activity in grape seeds (Adámez, et al., 2011) and in their marcs (Katalinic, et al., 2010), pomegranate peels (Al-Zoreky, 2009), lemon peels (Mahmud, et al., 2009), green walnut husks (Oliveira, et al., 2008), among others. In this study, wastes from food and beverage industries and from large fruit and vegetable distribution centers were evaluated for the presence of antimicrobial compounds with activity against microorganisms commonly associated with food toxico-infections such as Staphylococcus aureus, Listeria monocytogenes, Salmonella Enteritidis and Escherichia coli. In addition, the chemical composition of wastes that exhibited the greatest antimicrobial potentials was determined.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Export Date: 18 October 2014
    Journal of food and nutrition research 01/2014; 53(2):180-188. · 0.44 Impact Factor

Full-text (2 Sources)

Available from
Jun 3, 2014