Evaluation of novel green walnut liqueur as a source of antioxidants: Multi-method approach

Abstract

In this study, a novel green walnut liqueur (GWL) based on green walnuts, as the main ingredient, with the addition of fruits, aromatic plants, chocolate and honey, was produced at the pilot-scale. Antioxidant activity (AO) of the obtained GWL was determined using multiple AO assays in parallel, standard spectrophotometric (FC, DPPH and FRAP) and recently developed electrochemical ones, HydroxoPerhydroxoMercury(II) Complex and Mercury Reduction Antioxidant Power, and compared to similar commercial alcoholic beverages. Characterization of the GWL in terms of volatile and polyphenolic components was performed using SPE-GC-MS and HPLC-DAD-MS/ MS, respectively. Sensory quality assessment was performed by experts in the field of sensory analysis of alcoholic beverages, using a scoring method. According to all AO assays applied, AO activity and total phenolics content of GWL were superior in comparison to commercial spirits considered. The volatile fraction of GWL was mainly composed of eugenol, a-terpineol and vanillin, while the most prevalent phenolic compounds were gallic (5.054 mg/L) and chlorogenic acid (1.307 mg/L) and flavonoids such as catechine (0.882 mg/L), quercetin (0.499 mg/L) and its sugar-conjugated derivatives, quercetin 3-O-glucoside (0.774 mg/L) and quercetin-3-Orhamnoside (0.614 mg/L). Gallic acid is the major contributor to total AO activity, especially determined by DPPH and FRAP, followed by catechine, quercetin and chlorogenic acid. Among the terpenoids, contribution of eugenol to total AO activity is estimated as the highest. Excellent sensory quality (18.52 of maximum 20 scores) was ascribed to GWL. Consequently, the presence of bioactive compounds and high AO activity of GWL, in addition to high sensory quality score, indicates a high market potential for this high-value product.

Walnut (Juglans regia L.) Leaves and Green Husks: Their Functional Properties, Health Benefits and Potential Use in Foods

“…Ceviz yaprağının ve yeşil kabuğunun gıda endüstrisinde kullanım alanları ve uygulamalarına ait bazı araştırma sonuçları Tablo 2'de özetlenmiştir. Yapılan çalışmalar incelendiğinde; ceviz yaprağı ve yeşil kabuğunun gıdalarda fonksiyonel özelliği artırmak [37,45,63,64], antioksidan etki sağlamak ve raf ömrünü uzatmak [20,21,[65][66][67][68][69]…”

The Effect of Adding Spices to Green Walnut Tinctures on Their Polyphenolic Profile, Antioxidant Capacity and Action on Renal Cells

“…Green nuts are used in folk medicine and pharmacology as well as in the food industry-for the production of jams and liqueurs [3,4]. Beneficial health effects of unripe Juglans regia L. nuts were described by many authors [5][6][7].…”

“…In the case of the Nocino liqueur, depending on the recipe, flavor additives such as cloves, cinnamon, coriander, coffee beans, and lemon zest are used [14]. There are also attempts to use innovative additives such as chocolate, fruit, or honey [3].…”

Tailored Functionalization of Natural Phenols to Improve Biological Activity

“…In view of their importance, studies were aimed at breeding plants able to increase the content of bioactive phenols [ 23 ]. The research in the field continues, and more and more plants are investigated for their phenolic content and related bioactivity [ 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 ]. The antioxidant activity of natural phenols has been related to their scavenger ability towards free radicals [ 42 ].…”