Diversity of Phytochemical and Antioxidant Characteristics of Black Mulberry (Morus nigra L.) Fruits from Turkey

Abstract

Black mulberry (Morus nigra L.) fruits are known due to their delicious, sweet and slightly acid flavor and high anthocyanin content. In the present study, the diversity of phytochemical, sensory, and antioxidant characteristics of the fruits of 20 black mulberry genotypes, from the Artvin region of Turkey, were evaluated. As important phytochemical assessments in fruits, we chromatographically (HPLC/DAD) determined glucose (7.22 to 11.10 g/100 g fresh weight (fw)) and fructose content (6.32 and 9.94 g/100 g fw), as well as predominant organic acid in black mulberry genotypes fruits—malic acid (6.02–11.44 g/100 g fw), followed by citric acid. Titrative determination was used for ascorbic acid, finding contents of 17.41–28.33 mg/100 g fw. There was found a great diversity of sensory (taste, juiciness, and aroma) characteristics, indicating a richness of the fruit germplasm. Antioxidant parameters, such as total phenolic (TP) and anthocyanin (TA) content, were assessed spectrometrically; antioxidant activity (AA) was assessed by DPPH and FRAP assays; individual flavonoids and phenolic acids were determined chromatographically (HPLC/DAD). Antioxidant characteristics of the fruits, defined by TP and TA content, ranged from 1951 to 2733 μg GAE/g fw and 508–712 μg C3GE/g fw, respectively. The most abundant compounds of flavonoids and phenolic acids groups were determined to be rutin (47.10–97.20 mg/100 g fw) and chlorogenic acid (51.3–90.8 mg/100 g fw). AA results, measured by the DPPH method as EC50 value, ranged between 16.10 and 25.45 μg/mL; a FRAP assay revealed values of AA between 9.80 and 13.22 μmol TE/g fw. Significant differences in phytochemical and antioxidant qualities were observed among the analyzed M. nigra genotypes. Regarding the best values of phytochemical and antioxidant characteristics, three genotypes of M. nigra were selected to be recommended for fruit production. The results thus highlight the potential for the exploitation of local black mulberry genotypes through crop selection and breeding program.

The Darker the Better: Identification of Chemotype Profile in Soroses of Local and Introduced Mulberry Varieties with Respect to the Colour Type

“…Generally, black and red mulberry infructescences have lower total sugar content compared to white mulberries, which are much sweeter [81]. In this study, this is evidenced by the higher value of the sugar:organic acid ratio in the yellowish-white and light pink infructescences compared to the black and reddish-black infructescences.…”

Blackberries and Mulberries: Berries with Significant Health-Promoting Properties

“…The weight of M. nigra ranges from 4.18 g to 5.55 g, while moisture content is around 78.03 fw and is the highest found on the Morus species [30,35,41]. Total ash content is around 0.50 g per 100 g dry weight (dw), whereas pH values range from 3.43 to 4.78 [35,42] and TA between 0.17% and 1.97% [43,44].…”

“…Sugars are essential to a fruit's general taste character, nutritional value, and caloric density. They are the primary result of photosynthesis, and are required for the development of plant cell walls, energy production, and the formation of a number of signaling molecules at cellular and tissue levels, participating in the formation of aroma compounds [41]. Since most customers prefer sweet fruits, a higher fructose concentration is preferred because fructose is typically sweeter than glucose and sucrose [24].…”

“…Fructose, glucose, sucrose, trehalose, and raffinose are found in R. fruticosus and M. nigra. Comparing both, M. nigra contains more total and reduced sugars, but lower levels of saccharose (Table 1) [25,41,[47][48][49]. The carbohydrates most found in blackberries and mulberries are glucose and fructose.…”

“…Certain elements, such as calcium (Ca), iron (Fe), and zinc (Zn), are deficient in certain populations [48]. Fruit mineral composition is affected by growth circumstances, such as soil and geographical location, as well as species or varieties [41].…”