Olaniyi Amos Fawole

Antibacterial, antioxidant and tyrosinase-inhibition activities of pomegranate fruit peel methanolic extract.

BackgroundThis study evaluated, using in vitro assays, the antibacterial, antioxidant, and tyrosinase-inhibition activities of methanolic extracts from peels of seven commercially grown pomegranate cultivars.MethodsAntibacterial activity was tested on Gram-positive (Bacillus subtilis and Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli and Klebsiella pneumonia) using a microdilution method. Several potential antioxidant activities, including radical-scavenging ability (RSA), ferrous ion chelating (FIC) and ferric ion reducing antioxidant power (FRAP), were evaluated. Tyrosinase enzyme inhibition was investigated against monophenolase (tyrosine) and diphenolase (DOPA), with arbutin and kojic acid as positive controls. Furthermore, phenolic contents including total flavonoid content (TFC), gallotannin content (GTC) and total anthocyanin content (TAC) were determined using colourimetric methods. HPLC-ESI/MSn analysis of phenolic composition of methanolic extracts was also performed.ResultsMethanolic peel extracts showed strong broad-spectrum activity against Gram-positive and Gram-negative bacteria, with the minimum inhibitory concentrations (MIC) ranging from 0.2 to 0.78 mg/ml. At the highest concentration tested (1000 μg/ml), radical scavenging activities were significantly higher in Arakta (83.54%), Ganesh (83.56%), and Ruby (83.34%) cultivars (P< 0.05). Dose dependent FIC and FRAP activities were exhibited by all the peel extracts. All extracts also exhibited high inhibition (>50%) against monophenolase and diphenolase activities at the highest screening concentration. The most active peel extract was the Bhagwa cultivar against monophenolase and the Arakta cultivar against diphenolase with IC50 values of 3.66 μg/ml and 15.88 μg/ml, respectively. High amounts of phenolic compounds were found in peel extracts with the highest and lowest total phenolic contents of 295.5 (Ganesh) and 179.3 mg/g dry extract (Molla de Elche), respectively. Catechin, epicatechin, ellagic acid and gallic acid were found in all cultivars, of which ellagic acid was the most abundant comprising of more than 50% of total phenolic compounds detected in each cultivar.ConclusionsThe present study showed that the tested pomegranate peels exhibited strong antibacterial, antioxidant and tyrosinase-inhibition activities. These results suggest that pomegranate fruit peel could be exploited as a potential source of natural antimicrobial and antioxidant agents as well as tyrosinase inhibitors.

Phytochemical content, antioxidant capacity and physicochemical properties of pomegranate grown in different microclimates in South Africa

We investigated the antioxidant and physicochemical properties of pomegranate (Punica granatum cv. Bhagwa) fruit grown in three microclimates in South Africa. The physicochemical properties of fruit peel and arils differed among the growing locations, including weight and redness color of both peel and arils. Contents of vitamin C, anthocyanin and total phenolics were 0.67–1.41 mg ml−1, 0.07–0.16 mg ml−1 and 8.54–13.91 mg ml−1, respectively. Fruit grown in locations with high light intensity had higher vitamin C content and lower phenolic content than those of fruit from low-altitude locations and high light intensity. The pH of juice did not significantly differ among locations, whereas significant variation was observed in total soluble solids (TSS), titratible acidity (TA) and TSS:TA ratio. Fruit from locations with low rainfall had high TSS and low TA. Principal component analysis was used successfully to classify fruit by growing location on the basis of antioxidant and phytochemical contents.

Physicomechanical, phytochemical, volatile compounds and free radical scavenging properties of eight pomegranate cultivars and classification by principal component and cluster analyses

Purpose – The purpose of this study was to characterize fruit properties of pomegranate cultivars grown in South Africa in order to provide information to assist in selecting cultivars for food and industrial purposes, as well as to optimize postharvest handling and processing. Design/methodology/approach – The physical, textural and chemical properties as well as volatile profile and free radical scavenging capacity of eight cultivars (cvs “Acco”, “Arakta”, “Bhagwa”, “Ganesh”, “Herskawitz,” “Molla de Elche”, “Ruby”, and “Wonderful”) were quantified to demonstrate the diversity among the characters of the commercially grown cultivars. Findings – Statistically significant differences were found between cultivars for most of the evaluated characters, primarily highlighting the genetic diversity among the cultivars. The classification of fruit cultivars based on quality traits (such as size, texture, colour, soluble solids, acidity, juiciness and phenolics) showed the great potential of the cultivars for pro...

Composition of trace and major minerals in different parts of pomegranate (Punica granatum) fruit cultivars

Purpose – Pomegranate (Punica granatum L.) fruit is highly valued for its delicious edible arils and health benefits. In this study, a comparative study on elemental composition of seven pomegranate cultivars was determined in the fruit rind, mesocarp and arils.Design/methodology/approach – The concentrations of major elements (N, P, K, Ca, Mg, S, Cl and Na) and trace elements (Mn, Fe, Cu, Zn, B, Ni, Co, Cr, Pb, Cd, Se, Al, As, Li, Sr, Ti and V) were determined using an inductively coupled plasma optical emission spectrometry (ICP‐OES) calibrated with different concentrations of standard solutions of the minerals.Findings – The highest amounts of N, P, S and Cl were found in Bhagwa cultivar, while Arakta, Ruby and Wonderful had the highest amount of Mg, Ca, and Na, respectively. P, Fe, Zn, Ti, V were more in quantity in the edible portion, while the other mineral elements were in larger proportions or in some cases were only found (Co, Al, As) in the non‐edible fractions of fruit. Among the major mineral ...

Effects of different maturity stages and growing locations on changes in chemical, biochemical and aroma volatile composition of 'Wonderful' pomegranate juice.

BACKGROUND This study investigated the changes in chemical attributes of pomegranate fruit such as total soluble solids (TSS), titratable acidity (TA), TSS/TA ratio, pH, individual compounds (organic acids and sugars) and volatile composition as affected by fruit maturity status and growing location (Kakamas, Koedoeshoek and Worcester in South Africa). Headspace solid phase microextraction coupled with gas chromatography/mass spectrometry was used for volatile analysis. RESULTS A significant increase in TSS from 14.7 ± 0.6 to 17.5 ± 0.6 °Brix was observed with advancement in fruit maturity, while TA decreased from 2.1 ± 0.7 to 1.1 ± 0.3 g citric acid per 100 mL across all agro-climatic locations investigated. Fruit TSS/TA ratio and pH increased from 7.8 ± 2.6 to 16.6 ± 2.8 and from 3.3 ± 0.1 to 3.6 ± 0.2 respectively during fruit maturation across all agro-climatic locations. Fructose and glucose concentrations increased continually with fruit maturity from 69.4 ± 4.9 to 91.1 ± 4.9 g kg(-1) and from 57.1 ± 4.7 to 84.3 ± 5.2 g kg(-1) respectively. A total of 13 volatile compounds were detected and identified, belonging to five chemical classes. The most abundant volatile in unripe and mid-ripe fruit was 1-hexanol, while 3-hexen-1-ol was highest at commercial maturity. CONCLUSION Knowledge on the impact of fruit maturity and agro-climatic locations (with different altitudes) on biochemical and aroma volatile attributes of pomegranate fruit provides a useful guide for selecting farm location towards improving fruit quality and the maturity stage best for juice processing.

Influence of storage temperature and duration on postharvest physico-chemical and mechanical properties of pomegranate fruit and arils

Physico-chemical and mechanical properties for pomegranate (cv. Wonderful) were determined during 5 months of storage at 5°C, 7.5°C, and 10°C with 92% relative humidity (RH) and at 21°C with 65% RH. The results showed that weight loss increased with temperature and storage period. Only fruits stored at 5°C and 7.5°C lasted for 5 months, with a weight loss of 27.67% and 45.67%, respectively. Furthermore, the primary source of moisture loss was the fruit peel, and this resulted in over 30% reduction in peel thickness after a 5-month storage period. Colors of fruit and arils decreased with prolonged storage duration. Furthermore, total soluble solid (TSS), pH, TSS:titratable acidity, and BrimA increased throughout the storage period. Fruit puncture resistance as well as fruit compression parameters such as firmness, toughness, and bioyield decreased with storage temperature and duration. These findings showed that fruit should be stored between 2 and 3 months at 5°C to ensure the best internal and external quality attributes.

Classification of 'Granny Smith' apples with different levels of superficial scald severity based on targeted metabolites and discriminant analysis

To study the metabolic changes in ‘Granny Smith’ apples with different severities of superficial scald, fruit were stored in normal refrigerated air (0°C, 95% RH) for 12 weeks followed by 7 d shelf-life under room conditions (20°C, 65% RH). Fruit were graded to five groups based on scald severity and analysed for ethylene, α-farnesene and 6-methyl-5-hepten-2-one (MHO) levels. Reactive oxygen species (ROS) were measured by confocal laser-scanning microscopy on apple peel treated with fluorescent probe 2’,7’-dichlorodihydrofluorescein diacetate. Ethylene production rate, α-farnesene and MHO contents and ROS intensity increased with increasing scald severity but declined in severely scalded fruit. Malondialdehyde (MDA) concentration in fruit peel, a measure of membrane damage, increased linearly (R=0.891) with increase in scald severity. Discriminant analysis was used to classify fruit by scald severity on the basis of metabolites accumulated. The stepwise model indicated that three attributes (ROS, ethylene production and MDA) contributed significantly (R 2 ≥0.5) to the separation of the five scald severity indexes, with ROS having the highest contribution (partial R² =0.961; p<0.0001), followed by ethylene (R 2 =0.718; p<0.0001) and MDA (R 2 =0.578; p<0.0001).