Onur Saracoglu

Total phenolic distribution of juice, peel, and seed extracts of four pomegranate cultivars

The total phenolic distribution of juice, peel, and seed extracts of four Turkish pomegranate, Punica granatum L., cultivars (“Lefan,” “Katirbasi,” “Cekirdeksiz-IV,” and “Asinar”) was investigated. Total phenolic compounds were determined with the Folin–Ciocalteu colorimetric method. The results showed that the levels of total phenolic compounds changed depending on cultivars and fruit parts. In all cultivars, the highest levels of total phenolic content were obtained from the peel extracts. The total phenolic content ranged from 1775.4 to 3547.8 mg gallic acid equivalent (GAE)/L among the cultivars. However, the total phenolic content of pomegranate juice and seed extract ranged from 784.4 to 1551.5 mg GAE/L and 117.0 to 177.4 mg GAE/L, respectively. “Lefan” displayed the highest amount of the total phenolic content among the four popular cultivars tested.

Determining total phenolic content and total antioxidant capacity of loquat cultivars grown in Hatay

Several fruit characteristics of five loquat (Eriobotrya japonica (Thunb.) Lindl.) cultivars/selections grown in Dörtyol, Hatay, Turkey were investigated in 2008. The cultivars/selections included ‘Baduna 5’, Güzelyurt 1, ‘Hafif Çukurgöbek’, ‘Ottaviani,’ and Type 1. The characteristics evaluated included fruit weight, width, length, seed number and weight, flesh/seed ratio, total soluble solids (TSS), pH, acidity, total phenolic (TP) content, and total antioxidant capacity (TAC), determined by the ferric reducing antioxidant power (FRAP) assay. The analyses were conducted by three replicates, with 30 fruits in each replicate. The results indicated that there were significant differences among the cultivars, for all the traits tested. For example, ‘Hafif Çukurgöbek’ and ‘Ottaviani’ had smaller fruits than others, although ‘Hafif Çukurgöbek’ had heavier seeds. The flesh/seed ratio was the highest in Type 1, while ‘Hafif Çukurgöbek’ had the highest pH and high soluble solids. ‘Baduna 5’ and ‘Hafif Çukurgöbek’ had the highest acidity. The TP ranged from 129 (‘Baduna 5’) to 578 (‘Hafif Çukurgöbek’) mg gallic acid equivalent (GAE)/kg fresh fruit (fw). ‘Hafif Çukurgöbek’ also had the highest FRAP mean (12.1 mmol Trolox Equivalent (TE)/kg fw). The results suggest that loquat cultivars have a variable range of TP content and a relatively high total antioxidant capacity, which is crucial for human health.

Antioxidant capacity and chemical properties of selected barberry (Berberis vulgaris L.) fruits

Six purple-black barberry accessions (Berberis vulgaris L.) were obtained from various sites in Sivas province of Turkey. Fruits were analyzed for their total phenolic (TP), total monomeric anthocyanin (TMA) contents and for their antioxidant capacity by the ferric reducing antioxidant power (FRAP) and TEAC assays. Sugar and organic acid composition were also determined by HPLC. TP and TMA contents were measured using the Folin-Ciocalteu reagent and pH differential methods, respectively. Variability between the accessions was not high. Variability among accessions was greatest for FRAP content (C.V. 17.9%); individuals ranged from 41.0 to 65.6 μmol TE·g−1 on a fresh weight basis. Variation among the accessions was also evident for TP, TMA, and TEAC values (C.V. 16.21%, 14.85%, and 7.13%, respectively). The major sugars of barberry fruits were glucose (8.84 g·100 mL−1) and fructose (6.12 g·100 mL−1) and dominant organic acids were malic (7.59 g·100 mL−1) and citric (1.34 g·100 mL−1). Within this limited study of six different accessions, chemical profile and antioxidant capacity of barberry fruits have rich source of natural antioxidant substances.

The effect of NAA (1-naphthalene acetic acid) and AVG (aminoethoxyvinylglycine) on physical, chemical, colour and mechanical properties of Braeburn apple

Abstract Recently, plant growth regulators have been used for multiple purposes in tree fruits. NAA (1-naphthalene acetic acid) and AVG (aminoethoxyvinylglycine) have been widely used in apple fruit. NAA and AVG have been used to control preharvest fruit drop and improve the quality of fruit. In this study, the effects NAA (20 mgL–1), AVG (500 mgL–1) and control (non treatment) treatments on physical, chemical, colour characteristics and mechanical properties of apple (cv. Braeburn) were investigated. The higher length, width, thickness, geometric mean diameter, fruit mass, surface area, projected area, volume, fruit and bulk densities were obtained in AVG treatment. Total acidity, total soluble solid content and starch starch index were higher in control as compared to NAA and AVG treatments. Total phenolic content of the flesh apple was higher than the other treatments. While total antioxidant activities of skin and flesh fruit were higher in AVG according to FRAP method, total monomeric anthocyanin was lower in AVG as compared to the other treatments. AVG treatment generally had positive impacts on fruit removal force, skin and flesh firmnesses because retarding the fruit ripening.