Review on the “Biological Applications of Okra Polysaccharides and Prospective Research”

Investigation and prediction the extensional viscosity of okra mucilage using Giesekus model

BACKGROUND: Okra is a vegetable that is widely grown around the world. Okra mucilage contains a high mucus concentration that can be useful for supporting the swallowing process. Although the extensional rheology of okra mucilage is essential to its flow, its extensional viscosity has not received much attention. OBJECTIVE: Using a filament stretching rheometer, the extensional viscosity of the mucilage in okra was examined. The Giesekus model is also used to predict this parameter. METHODS: The okra mucilage with different concentrations was extracted from fresh okra. The extensional viscosity was measured using a filament breakup apparatus. The diameter of the liquid bridge was measured by a laser micrometer and it was also observed by a high-speed camera. A rotational rheometer was used to measure the shear viscosity. In addition, the master curves for the shear viscosity were plotted to eliminate the influence of solvent and shear rate and evaluate the influence of concentration on the elasticity of okra mucilage. The okra mucilage shear and extensional viscosity were predicted using the Giesekus model. RESULTS: Every sample of okra mucilage exhibits shear thinning behavior. Additionally to having a high extensional viscosity that is hundreds of times higher than its shear viscosity, okra mucilage also exhibits stretching phenomena. The master curves demonstrated that the pseudoplasticity of the okra mucilage increased along with the concentration. The rheological behavior of the mucilage in okra can be explained by the Giesekus model. CONCLUSIONS: Okra mucilage’s shear viscosity exhibited shear thinning behavior and a strong extensional viscosity that was significantly higher than its shear viscosity. The shear and extensional viscosity of okra mucilage can be described and predicted using the Giesekus model.

Phytochemical Screening, Nutritional Value, Anti-Diabetic, Anti-Cancer, and Anti-Bacterial Assessment of Aqueous Extract from Abelmoschus esculentus Pods

Known for its high nutritional and medicinal value, okra (Abelmoschus esculentus) is commonly used for replacing plasma and expanding blood volume in humans. It is a major economic crop cultivated in tropical and subtropical regions worldwide. The present study aimed to investigate and evaluate the nutritional properties and prospective applications of the consumable parts of okra. The total ash content (mineral content), carbohydrate, crude fiber, fat, protein, and moisture fractions of okra pod aqueous extract were determined. The results show that okra aqueous extract contained 84.670–87.650% moisture, 1.514–1.197% ash, 7.857–8.261% carbohydrate, 2.367–3.410% crude protein, and 6.781–8.314% crude fiber. Okra was determined to have high nutritional value, with γ-tocopherol and α-tocopherol contents about 2.67 mg/100 g and 1.62 mg/100 g, respectively. High-performance liquid chromatography (HPLC) was performed to determine the sugars present in okra aqueous extract. The water-soluble polysaccharide content was 10.22–16.45 g/100 g. The tested aqueous extract was a rich source of total phenolic compounds in gallic acid equivalents (288.2–3426.2 mg/100 g), chlorophyll a (3.53 mg/100), chlorophyll b (2.43 mg/100), and carotenoids (1.3 mg/100 g). The detected minerals were Ca, Mg, Cu, Zn, Fe, K, Na, and Mn. Atomic absorption spectrometry analysis of these ashed minerals was performed. In addition to the nutritional benefits, okra pods exhibited antimicrobial, anticancer, and antioxidant properties. The aqueous extract was found to be potentially active against bacterial strains of Staphylococcus aureus (MIC value = 21.8 mg/mL), Escherichia coli (MIC value = 18.7 mg/mL), Bacillus cereus (MIC value = 20.7 mg/mL), and Klebsiella pneumoniae (MIC value = 20.2 mg/mL). Okra aqueous extract exhibited inhibitory activity against α-amylase (IC50 = 120 µg/mL) and α-glucosidase (IC50 = 115 µg/mL). The okra extract exhibited high anticancer activity, concentration-dependent and with an IC50 value of about 158.3 mg/mL. The results indicated that okra pods have nutritional and medicinal properties and, hence, can be used as a functional food and broad-spectrum nutraceutical supplement.

Okra (Abelmoschus esculentus L.) as a Potential Functional Food Source of Mucilage and Bioactive Compounds with Technological Applications and Health Benefits

Abelmoschus esculentus has fruit popularly known as okra and belongs to the Malvaceae family. It is commonly used in cooking but also in traditional medicine in the treatment of worms, dysentery, inflammation, and also irritation of the stomach, intestines, and kidneys, as it is a potential functional food. Its mucilage is a highly viscous polysaccharide that is mostly composed of monosaccharides D-galactose, L-rhamnose, and galacturonic acid, as well as proteins and minerals. The functional properties of okra mucilage have been widely studied, mainly for its potential antidiabetic activity; thus, its use as adjuvant or nutraceutical therapy for diabetes is very promising. Due to its rheological properties, it is a potential resource for pharmaceutical and food applications. Okra mucilage can be extracted by several methods, which can directly influence its physicochemical characteristics and biological activity. Features such as low cost, non-toxicity, biocompatibility, and high availability in nature arouse the interest of researchers for the study of okra mucilage. The survey of research on the applications of okra mucilage highlights the importance of using this promising source of bioactive compounds with interesting technological properties. The potential of okra as a functional food, the properties of okra mucilage, and its technological applications are discussed in this review.