Amino acid composition, mineral profile, free radical scavenging ability, and carbohydrase inhibitory properties of Moringa oleifera seed globulin, hydrolysates, and membrane fractions.

The nutritional-amino acid profile and mineral element of Moringa oleifera seed globulin (GLO) and its hydrolysates as well as the in vitro bioactive properties-antioxidant, alpha-amylase, and alpha-glucosidase inhibition of the GLO, hydrolysates, and membrane fractions were reported. The results showed that M. oleifera contained significant amounts of essential amino acids (EAA), which are more than the minimum required by the Food and Agricultural Organization for children, except for tryptophan, which was the limiting amino acid. However, hydrolysis mostly led to a reduction in the contents of the EAA. While the process of hydrolysis and the subsequent membrane fractionation produced peptides with improved activities in 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid radical scavenging ability and oxygen radical absorbance capacity, this process produced no activities in superoxide radical scavenging ability, α-amylase, and α-glucosidase inhibitory potentials of some of the hydrolysates and peptides fractions. In summary, M. oleifera seed peptide fraction (<3 kDa) from the alcalase-derived hydrolysate contains potent antioxidants but relatively low in vitro antidiabetic properties. PRACTICAL APPLICATIONS: Several studies have established the ability of proteins, including hydrolysate and peptide fractions to provide some bioactive properties such as antioxidant, antidiabetic, anti-inflammatory among others. However, because protein functionalities are influenced by several factors such as the source, type, processing method employed among others, research has continued to evaluate the bioactivities of proteins under different conditions. In this study, therefore, we reported the impact of processing methods (hydrolysis, enzyme type, and peptide size) on the nutritional, antioxidant, and in vitro antidiabetic properties of M. oleifera seed globulin, its hydrolysates, and membrane fractions. This information plays an important role in the further exploitation of M. oleifera seed proteins in the development of functional foods and nutraceuticals.

In vitro antihypertensive and antioxidative properties of trypsin-derived Moringa oleifera seed globulin hydrolyzate and its membrane fractions.

Moringa oleifera seed globulin was hydrolyzed with trypsin and fractionated to produce <1, 1-3, and 3-5 kDa peptide sizes. These were evaluated for antioxidant properties: DPPH, hydroxyl radical scavenging assays, FRAP, and metal chelation tests; and in vitro antihypertensive properties: ACE and renin inhibition. Membrane fractionation led to improved antioxidative properties of 29.13% (<1 kDa), 180% (<1 kDa), and 30.58% (1-3 kDa) for DPPH, FRAP, and metal iron chelation, respectively. There was however 48.77% reduction (1-3 kDa) in hydroxyl radical scavenging activity. There was also improvement in ACE inhibitory potentials of the peptides with the 1-3 kDa peptide showing significantly highest ACE inhibition (72.48%)but very low (17.64%, 1-3 kDa) inhibition against the renin. It was concluded that hydrolysis of M oleifera seed globulin with trypsin produced peptides and peptide fractions with potential antioxidant and antihypertensive properties.

Amino acid composition and antioxidant properties of Moringa oleifera seed protein isolate and enzymatic hydrolysates.

The aim of this work was to compare the antioxidant and angiotensin converting enzyme (ACE) inhibitory properties of Moringa oleifera seed protein isolate (ISO) and its enzymatic protein hydrolysates. ISO was subjected to enzymatic (alcalase, pepsin and trypsin) hydrolysis to obtain alcalase isolate, pepsin isolate and trypsin isolate hydrolysates (AIH, PIH, TIH). Amino acid composition was similar for the samples except that TIH had lower Sulphur-containing amino acids while PIH was lower in tryptophan. All the samples were tested for antioxidant properties through free radical scavenging abilities such as 2,2 diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl radical scavenging assays as well as ferric reducing antioxidant power (FRAP) and metal ion chelation assays. The maximum percentage inhibition obtained for the samples from the different assays are: DPPH, 36% (PIH); FRAP, 0.04% (PIH); hydroxyl radical scavenging activity, 42.98% (ISO); and inhibition of metal ion chelation, 29.46% (AIH). AIH (79.3%) had the highest ACE-inhibitory activity followed by TIH (75.1%) while PIH (43.0%) had the least. Generally, the hydrolysis process produced hydrolysates with improved antioxidant and ACE-inhibitory properties when compared to the isolate. We conclude that enzymatic hydrolysis with alcalase, pepsin and trypsin may be used to produce M. oleifera seed protein hydrolysates with potential to be used as ingredients for the formulation of functional foods and nutraceuticals.

Development of value-added nutritious crackers with high antidiabetic properties from blends of Acha (Digitaria exilis) and blanched Pigeon pea (Cajanus cajan).

Pigeon pea was treated by blanching and used to supplement acha flour for the development of functional cracker biscuits. The flour ratios for acha and pigeon pea were 100:0 (ACC), 80:20 (APC1), and 70:30 (APC2), respectively. The developed cracker biscuits were evaluated for chemical acid compositions, antioxidant, as well as antidiabetic properties. Protein contents of the formulated crackers increased with increase in supplementation with pigeon pea flour. The antinutrient content of the formulated snack was low hence may not adversely affect nutrient bioavailability. Glutamic and aspartic acids were the predominant amino acids while methionine and lysine significantly increased as a result of supplementation with pigeon pea flour. The biscuit exhibited good antioxidant properties indicated by its strong ability to scavenge hydroxyl, superoxide, DPPH radicals, and reduced Fe3+ to Fe2+. The formulated snack especially APC2 possessed low glycemic index (47.95%) and significantly inhibited the key digestive enzymes (α-amylase and α-glucosidase). All parameters evaluated indicated that APC2 could serve as a functional snack in the management of hyperglycemia (diabetes) and prevention of associated degenerative diseases.

Enhancing Sensory Perception of Plant Based Nutraceutical Drinks by Combining Plants from Different Sources: A Preliminary Study of Tea and Ginger Blend.

Tea-ginger drink was selected for evaluation due to its nutraceutical potential. Panelists rated preference for drinks prepared from tea, ginger, and tea+ginger powder for colour, taste, and aroma. The obtained data were evaluated using analysis of variance, principal component analysis, and agglomerative hierarchical clustering. Also the colour preference scores were evaluated against instrumental colour measurements. The ginger drink had lower rating for colour preference and the tea drink had lower ratings for aroma and taste preference. However, the tea-ginger drink led to enhanced colour, aroma, and taste ratings. The colour preference was found to have highest correlation coefficient with the hue and chroma of the drinks [r(58)=-0.583, P<0.05 and r(58)=0.566, P<0.05]. This study suggests that a sensory quality deficiency in a particular plant based drink could be compensated for by blending the drink with another plant based drink. This approach could help improve the uptake of plant based nutraceutical drinks.

Changes in Nutrient Composition, Antioxidant Properties, and Enzymes Activities of Snake Tomato (Trichosanthes cucumerina) during Ripening.

Snake tomato (Trichosanthes cucumerina) has been cultivated and used as a replacement for Lycopersicum esculentum in many Asian and African diets. Matured T. cucumerina fruits were harvested at different ripening stages and separated into coats and pulps for analyses to determine their suitability for use in culinary. They were analyzed for the nutritional composition and antioxidant potential using different biochemical assays [1,1-diphenyl-2-picrylhydrazyl, 2,2'-azinobis( 3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging activities, and ferric reducing antioxidant power] and antioxidative enzymes activities. The nutritional composition revealed that T. cucumerina contains over 80% water and is very rich in fiber, thus it can serve as a good natural laxative. The lycopene and ß-carotene contents were especially high in the ripe pulp with values of 21.62±1.22 and 3.96±0.14 mg/100 g, respectively. The ascorbic acid content was highest in the pulp of unripe fruit with a value of 56.58±1.08 mg/100 g and significantly (P<0.05) decreased as ripening progressed. The antioxidant potential of the fruits for the 3 assays showed that unripe pulp> ripe coat> ripe pulp> unripe coat. There were decreases in the antioxidant enzymes (superoxide dismutase, ascorbate peroxidase, and glutathione reductase) activities, with the exception of catalase, as ripening progressed in the fruits. These decreased activities may lead to the softening of the fruit during ripening. Harnessing the antioxidative potential of T. cucumerina in culinary through consumption of the coats and pulps will alleviate food insecurity and help maintain good health among many dwellers in sub-Saharan Africa and Southeast Asia.

Multiresponse Optimization and Prediction of Antioxidant Properties of Aqueous Ginger Extract.

The influence of extraction temperature, powder concentration, and extraction time on the antioxidant properties of aqueous ginger extract was investigated. The possibility of estimating the antioxidant properties of the extract from its absorbance and colour properties was also investigated. Results indicated that powder concentration was the most significant factor to consider in optimizing antioxidant extraction. However, temperature and time still influenced the 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activity while extraction temperature influenced the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity of the extract. Using the total phenol content, total flavonoid content, ABTS radical scavenging activity, and DPPH radical scavenging activity of the extract, the multiresponse optimization condition for extraction of antioxidant based on the experimental range studied is 96°C, 2.10 g/100 mL, and 90 min. The absorbance of the ginger extract at 610 nm could be exploited for rapid estimation of its total flavonoid and polyphenol with a R2 of 0.713 and 0.753, respectively.

Optimization and prediction of antioxidant properties of a tea-ginger extract.

A response surface approach was used to investigate the effects of temperature, concentration, and time on the antioxidant properties (total flavonoid (TF), total phenol (TP), peroxide scavenging activity (PS), iron chelating activity (IC), DPPH radical-scavenging ability (DPPH), ABTS assay (ABTS)) of aqueous extract of tea-ginger (2:1) powder. Color indices, pH, and redox potential of the tea-ginger powder were also measured and used as independent variables for the prediction of antioxidant properties of the extract using ordinary least square (OLSR), principal component (PCR), and partial least square (PLSR) regression. The R (2) values for TP, TF, ABTS, and PS response surface models were 0.8873, 0.9639, 0.6485, and 0.5721, respectively. The OLSR, PCR, and PLSR were able to provide predictive models for DPPH, TP, and TF of the tea-ginger extract (P < 0.05). The PLSR gave the most parsimonious model with an R (2) of 0.851, 0.736, and 0.905 for DPPH, TP, and TF, respectively.