Phytochemical composition and antioxidant properties of methanolic extracts of whole and dehulled Bambara groundnut (Vigna subterranea) seeds.

The distribution of phytochemicals and their contribution to antioxidant potentials in whole and dehulled Bambara groundnut (BGN) seeds was evaluated. Whole BGN seeds were sorted using the testa and hilium colour and further grouped into whole and dehulled BGN seeds. Extractions of both whole and dehulled BGN seeds was done using methanol and the extracts assayed for total phenolics (TPC), flavanol, flavonol, anthocyanin content, oxygen radical absorbance capacity (ORAC) and ferric reducing antioxidant power (FRAP). Methanolic extract of whole BGN seed exhibited higher flavanol and flavonol content as well as significantly higher in-vitro antioxidant activities than dehulled BGN seeds. The TPC of whole BGN seed extract ranged from 3.6 to 11.0 GAE/g, while that of dehulled BGN ranged from 2.7 to 3.2 GAE/g. Identification of phenolics in whole and dehulled BGN seed extract using UPLC-qTOF-MS, revealed the presence of monoterpenoids (iridoids), phenolic acids, flavonoids and lignans. Bivariate correlations showed anthocyanin demonstrated weak positive correlation between flavanol, flavonol and ORAC for whole BGN seed extract; and negative correlation between flavanol, TPC, FRAP and ORAC for dehulled BGN. Aside the effect of dehulling, whole BGN seeds exhibited the presence of phytochemicals with beneficial properties for food and industrial application.

Effect of Wheat Bran Incorporation on the Physical and Sensory Properties of a South African Cereal Fried Dough.

This study investigated the effect of wheat bran (WB) supplementation on the physical and sensory properties of a South African cereal fried dough (magwinya). The physical properties, instrumental texture, and sensory profile were determined for magwinya (100:0, control) and for wheat flour to wheat-bran ratios of 95:5 (MWB5), 90:10 (MWB10), 85:15 (MWB15), and 80:20 (MWB20). An increase in the proportion of WB in the fried dough showed no significant difference on the specific volume (1.47-1.54) of samples. The chroma value (30.19-22.29), lightness (35.92-28.98), and hue angle (55.03-47.77) decreased, while ∆E increased distinctly with the addition of WB. Magwinya supplemented with WB was less cohesive and easy to chew. Significant correlations were found between instrumental hardness and sensory springiness (r = -0.63; p < 0.05), as well as between instrumental cohesiveness and chewiness (r = -0.71; p < 0.01). Two principal components were identified, which accounted for 85.1% of the variance in the instrumental data. A substitution level of 5 and 10% WB was similar to the sensory properties of the control in taste, texture, and overall acceptability and can replace part of the wheat flour in the cereal fried dough production.

Polyphenolic and Physicochemical Properties of Simple-Spined Num-Num (Carissa edulis) Fruit Harvested at Ripe Stage of Maturation.

Wildly grown in most regions of the world, Carissa edulis is a highly underutilised fruit with significant antioxidant characteristics. The phyto and physicochemical properties of C. edulis berries at different stages of ripening are evaluated in this work. Total flavonoids (TF), total phenolic content (TPC) and antioxidant activity were determined spectrophotometrically, while concentration of polyphenols was determined using liquid chromatography coupled to diode array detection and electrospray ionization mass spectrometry. Results showed that antioxidant activity was lowest (18.36 ± 0.12 mg TE/g) in RS3 and decreased with TPC upon increased ripening. Conversely, TF increased with ripening progression with TF found to be highest in RS3 (5.92 ± 0.03 mg CE/g). Identified phenolic acids in C. edulis were quinic acid, protocatechuoyl-hexose, neochlorogenic acid, chlorogenic acid, cryptochlorogenic acid and dicaffeoylquinic acid. Identified flavonoids included rutin, catechin, procyanidin dimer, procyanidin trimer, quercetin-3-O-glucosyl-xyloside, quercetin-3-O-robinobioside, quercetin-3-O-glucoside and quercetin-3-OH-3-methylglutaryl-glucoside. Physicochemical properties of C. edulis varied among samples with sugar/acid ratio of C. edulis ranging from 25.70 for RS1 to 50.36 for RS3. Ripening stage of C. edulis undoubtedly affects the phyto and physicochemical properties of C. edulis.

Phenolics and essential mineral profile of organic acid pretreated unripe banana flour.

Banana fruit (Musa spp) though rich in essential minerals, has also been implicated for the presence of phytochemicals which nonetheless beneficial, can also act as mineral inhibitors when in forms such as phenolic compounds, phytates and tannins. This study assayed the essential macro and trace minerals as well as phenolic compounds present in unripe banana flour (UBF) obtained from the pulp of four different cultivars. Unripe banana flour was processed by oven drying in a forced air oven dryer at 70°C upon pretreatment with ascorbic, citric and lactic acid. Organic acid pretreatment was done separately on each unripe banana cultivar at concentrations of 10, 15 and 20g/L. Phenolic compounds were profiled using liquid chromatography mass spectrometry electrospray ion (LC-MS-ESI) while essential minerals were determined using inductively coupled plasma atomic emission spectroscopy (ICP-AES) and mass spectroscopy (ICP-MS) respectively. Results of LC-MS-ESI assay of phenolics revealed the presence of flavonoids: epicatechin and myricetin 3-O-rhamnosyl-glucoside in varying concentrations in UBF. Essential mineral profile indicated that Zinc had the least occurrence of 3.55mg/kg (p<0.05), while potassium was the most abundant mineral at 14746.73mg/kg in UBF of all four banana cultivars. Correlation between phenolic compounds and essential minerals using Pearson's Correlation Coefficient test revealed weak and inverse association between flavonoids and most macro and trace minerals present in UBF samples. Organic acid pretreatment thus exhibited little effect on phenolics and essential minerals of UBF samples, though, inhibitory influence of phenolic compounds was recorded on essential minerals.

Morphological, physicochemical, and antioxidant profile of noncommercial banana cultivars.

Banana cultivars--Luvhele (MusaABB), Mabonde (MusaAAA), and Muomva-red (Musa balbisiana) --were characterized for morphological, physicochemical, and antioxidant properties. All three cultivars varied significantly (P < 0.05) in their morphology, pH, titratable acidity and total soluble solids with no significant difference in their ash content. Individual cultivars showed variations in flour starch granule when observed using a scanning electron microscope. Characterization of cultivars for total polyphenols (TPs) and antioxidant activity upon pretreatment with ascorbic, citric, and lactic acid shows that the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay of samples varied significantly as Muomva-red cultivar (1.02 ± 0.01 mg GA/g) expressed the highest DPPH activity at lactic acid concentration of 20 g/L. Total polyphenol content was also highest for Muomva-red [1091.76 ± 122.81 mg GAE/100 g (d.w.)]. The high amount of TPs present in these cultivars make them suitable source of bio-nutrients with great medicinal and health functions.

Effect of organic acid pretreatment on some physical, functional and antioxidant properties of flour obtained from three unripe banana cultivars.

Unripe banana flour (UBF) obtained from organic acid pretreatment of pulp from three non-commercial cultivars were profiled for physical, functional and antioxidant properties. UBF showed marked significant differences (p<0.05) in colour (CIEL(∗)a(∗)b(∗) and CIELCH) and water holding capacity with no significant difference in oil holding capacity. The total polyphenol content (TPC) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) differed significantly with M-red UBF recording high TPC (1130.39 ± 27.26 mg GAE/100g d.w.) at 10 g/L citric acid pretreatment. Correlation analysis between TPC and DPPH showed very strong positive correlation for Mabonde UBF in citric and lactic acid pretreatment (r = 0.999, p < 0.01; r = 0.985, p < 0.01), while inverse correlation was recorded in M-red UBF for ascorbic and lactic acid pretreatment (r = -0.031; r = -0.137). Organic acid pretreatment enhances the physical and antioxidant properties of UBF hitherto absent in composite food formulations.

Functional Properties and Postharvest Utilization of Commercial and Noncommercial Banana Cultivars.

Banana (Musa spp.) is one of the world's most important crops cultivated in tropical and subtropical regions of the world. Banana is a major source of macro-elements, especially potassium, and contains health-beneficial ingredients such as resistant starch, total dietary fibers, rapidly digestible starch, and slowly digestible starch. Oligosaccharides (fructooligosaccharides and inulin) and polyphenols ((+)-catechin, (-)-epicatechin, (-)-epigallocatechin, and gallic acid) are other ingredients present in bananas that have found application in the prevention of muscular contractions, regulation of blood pressure, prevention of colon cancer and diabetes, and in the cure of intestinal disorders when unripe. This review identifies the different commercial and noncommercial banana cultivars and their utilization. Commercial cultivars include Williams (M. acuminata cv. Williams), Dwarf Cavendish (M. acuminata cv. Petite Nain), Chinese Cavendish (M. acuminata cv. Chinese Cavendish), Grand Nain (M. acuminata cv. Grand Nain), and Goldfinger (M. acuminata cv. Goldfinger), with Mabounde and Luvhele identified as noncommercial varieties. Banana postharvest utilization includes its use as functional foods, prebiotics, probiotics, nutraceuticals, and processing into value-added products.