Functional foods of sub-Saharan Africa and their implications in the management of type 2 diabetes: A review.

Throughout the world, the prevalence of metabolic diseases in general and type 2 diabetes (T2DM) in particular is constantly growing, and sub-Saharan Africa (SSA) is not spared. The use of functional foods is a more practical option among the different approaches used in the management of T2DM owing to the fact that they are relatively less costly, safer, and more accessible. In addition to their low glycemic index just like foods currently used to manage diabetes, functional foods contain bioactive compounds such as polyphenols, dietary fibers, saponins, and peptides. They are so named because they have additional health advantages beyond their basic nutritional worth. Bioactive compounds can be found in a variety of SSA plant-based foods, such as spices, fruits, vegetables, legumes, starchy foods, prepared foods, mixed foods, and prepared dishes. The goal of this review is to highlight some of the investigations into the effectiveness of local food and their antidiabetic mechanisms that have been studied in various SSA regions. Using the literature review as a basis, the authors state that SSA foods are rich in various bioactive compounds capable of regulating blood sugar through enhanced glucose tolerance, antioxidant effects, insulin sensitivity, and inhibition or activation of some key enzymes of the glucose metabolism that are linked to the prevention and management of T2DM. Many of the cited findings are preliminary, obtained from cell and preclinical studies, and therefore other studies need to be done to demonstrate the full potential of these foods to serve as bases for dietary guidelines.

Effect of controlled differential sieving processing on micronutrient contents and in vivo antioxidant activities of Hibiscus sabdariffa L. calyxes powder.

Sun-dried calyxes of Hibiscus sabdariffa were finely grinded and fractionated by controlled differential sieving processing (CDSp) into four granulometric classes. The obtained powder fractions were examined for their micronutrient contents and in vivo antioxidant properties in high-fat diet induced oxidation model rats. Unsieved powder and lyophilized ethanolic extract were used for comparison. Micronutrient contents and antioxidant properties were significantly influenced (p < 0.05) by particle sizes. The mineral, vitamin, carotenoid and anthocyanin contents were shown to be higher in smaller powder particles. Comparatively, the ethanolic extract powder had the higher carotenoid, vitamin and anthocyanin contents while the superfine powders < 180 µm and 180-212 µm had the higher mineral contents and antioxidant properties which was characterized by high superoxide dismutase, catalase activities and low malondialdehyde production. Plant grinding followed by CDSp may be an option to improve micronutrient content and antioxidant activity of plant powders.

Micronutrients and in vivo antioxidant properties of powder fractions and ethanolic extract of Dichrostachys glomerata Forssk. fruits.

Dichrostachys glomerata powders were processed by sieve fractionation and ethanolic extraction followed by freeze-drying. The micronutrient contents and the in vivo antioxidant properties of powder fractions in rats' high-fat diet-induced oxidation model were determined. Sieved fractionation was achieved by finely grinding the Dichrostachys fruits and fractionating on a sieve column to retain particle of sizes <180, 180-212, 212-315, and ≥315 µm. Unsieved powder and lyophilized ethanolic extract were used as control. All the powders were examined for the minerals, total carotenoids, and vitamins contents. For in vivo antioxidant properties assessment, the individual powder was dissolved in water and administered to rats at the dose of 250 mg/kg body weight. Oxidation was induced by treating the rat with high-fat diet, and the measured parameters were malondialdehyde, superoxide dismutase, and catalase activities. The results showed a significant influence (p < .05) of particle size on the micronutrient contents and in vivo antioxidant properties. The smaller the particle size of the powder fractions, the higher the minerals, vitamins, total carotenoids contents, and antioxidant properties. Comparatively, the ethanolic powder had the highest carotenoids content, while the powders of particle size <180 µm and 180-212 µm had the highest minerals and vitamin contents. The highest antioxidant properties were characterized by high superoxide dismutase, catalase activities, and low malondialdehyde production. The grinding of Dichrostachys fruit followed by controlled differential sieving process may compete with ethanol extraction for an efficient concentration of bioactive compounds and micronutrients except carotenoids.

Effect of sieved fractionation on the physical, flow and hydration properties of Boscia senegalensis Lam., Dichostachys glomerata Forssk. and Hibiscus sabdariffa L. powders.

This study aimed at evaluating the effect of successive grinding and sieving processes on the physicochemical properties of powders obtained from Boscia senegalensis seeds, Dichostachys glomerata fruits and Hibiscus sabdariffa calyxes. Plant powders were fractionated into four granulometric classes and their properties were compared to those of unsieved powders. Mean particle size exerted a significant influence (p < 0.05) on the plant powders properties. The smaller the particle size of the powder fraction, the higher the protein, lipid and ash contents and the lower the carbohydrate and fiber contents. The decrease in particle size increased particle sphericity and elongation and enhanced flowability of B. senegalensis and D. glomerata powders, whereas an inverse tendency seemed to be observed for H. sabdariffa powders. Water absorption capacity, water solubility index and dispersibility were improved for finer particles for all plants. Sieve fractionation is a novel approach for improving physicochemical properties of plant powders.

Successive grinding and sieving as a new tool to fractionate polyphenols and antioxidants of plants powders: Application to Boscia senegalensis seeds, Dichrostachys glomerata fruits, and Hibiscus sabdariffa calyx powders.

The present investigation aimed at evaluating the effect of powder fractionation based on particle size on the chemical composition in macronutrients, polyphenol contents, and antioxidant properties of powders of Boscia senegalensis seeds, Dichrostachys glomerata fruits, and Hibiscus sabdariffa calyces. Significant differences (p < 0.05) among granulometric classes of each plant were observed for the chemical composition in macronutrients. A decrease in particle size of plant powders was associated with an increase in ash, protein, and fat contents, while carbohydrate content was lowered. The following Granulometric classes, [0-180 µm] for Boscia senegalensis, [180-212 µm] for Dichrostachys glomerata, and [212-315 µm] for Hibiscus sabdariffa, respectively, were found to maximize total phenolic content and antioxidant activity. These results confirm that the grinding and controlled differential screening technology is an approach may serve as a useful guide to obtain optimum polyphenol extraction and enhance antioxidant activity of plant products.

Dehulling reduces toxicity and improves in vivo biological value of proteins in vegetal milk derived from two mucuna (Mucuna pruriens L.) seeds varieties.

The present work was carried out to evaluate the nutritive quality (proximate and antinutrients composition) of vegetable milks prepared from whole and dehulled mucuna bean flours. Casein and mucuna milk diets were fed to rats (four weeks old; n = 8 per group) for 28 days to determine protein efficiency ratio (PER), net protein efficiency ratio (NPER), true and apparent digestibility (TD and AD, respectively), organ-to-body weight ratios and hematological parameters. The experimental design was a factorial design with two variety of mucuna (cochinchinensis and veracruz) and two treatments (whole and dehulled beans). Protein, total sugar, dry matter and ash-content of mucuna milks ranged from 6.40 to 12.13 g/100 mL, 10.52 to 13.08 g/100 mL, 8.59 to 12.88 g/100 g and 0.31 to 0.92 g/100 g, respectively. Milks from dehulled flours had lower contents of tannins (80-87.08 %), phytates (76.67-78.16 %) and L-Dopamine (44.45-66.66 %) than that from whole flours. The PER of dehulled mucuna diets were 22.76-21.74 %, but negative PER and low NPER was observed for whole mucuna milk diets. TD for dehulled mucuna milk (85.15-85.96 %) were higher and similar to casein when compared to that of whole mucuna milk (47.87-51.17 %). Rats fed with diets containing whole mucuna milk lost weight and had higher kidney weight. In addition, the rats fed with milk from whole mucuna flours showed significantly lower levels of lymphocytes, granulocytes, red blood cells, hemoglobin and hematocrit than that fed with dehulled mucuna milk.

Physicochemical and micro-structural properties of flours, starch and proteins from two varieties of legumes: bambara groundnut (Vigna subterranea).

This work is part of a large study aimed to evaluate the potential of bambara groundnut (Vigna subterranea) flour as starting raw material for the preparation of a widely cherished legume-based food product known as koki. Towards this objective, the flours from two varieties of bambara groundnut along with their respective starch and protein isolates were analyzed for some physicochemical and microstructural properties. It was observed that bambara flour contained appreciable amount of proteins (24.0-25.5 g/100 g), carbohydrates (57.9-61.7 g/100 g), fiber (3.45-3.68 g/100 g) and ash (3.65-3.85 g/100 g) with marginal differences between both varieties. The properties of starch and proteins isolated from the flours were different from one variety to another. In particular the starch granules of the white variety were larger (size range 10-35 µm) and polygonal while those from the black variety were smaller (size range 6-15 µm) and spherical in shape. In addition, the peak of gelatinization temperature was higher for white variety (81.7 °C) than for black variety (77.5 °C). The gelatinization temperature and the enthalpy of gelatinization of starch in the flours were systematically lower than for the starch isolates, suggesting an interaction of starch with other components on the gelatinization process.

Hypolipidemic and anti-atherogenic effect of aqueous extract leaves of Ficus glumosa (Moraceae) in rats.

Leaves of Ficus glumosa are used in northern Cameroon and southern Chad for the treatment of cardiovascular diseases, as food and as a stimulant for milk production in both women and animals. Atherosclerosis is a disease in which frequency increases with age. The first lesions appear at the young subject during adolescence. Atherosclerosis lesions appear very precociously and worsen with age. They interest the levels chronologically aortic, coronary then carotid. Age is a risk factor in that it reflects the exposure time of individual to the other risk factors. The frequency of the atherosclerosis increases with age because of the aging of the cells. This study was undertaken to evaluate the hypolipidemic and anti-atherosclerotic properties of aqueous extract of the leaves of F. glumosa in rats with hypercholesterolemia (HC). 60 male rats were fed for 4 weeks with a high-cholesterol diet (1%) and 3 doses (225, 300 and 375 mg/kg) of extract of F. glumosa were used in these experiments. The experiments were conducted under the same conditions with atorvastatin (1 mg/kg), as pharmacological reference substance. The effects of F. glumosa on weight gain, water and food consumption, levels of serum lipids and lipoprotein lipid oxidation and stress markers in the blood and liver were examined. The administration of F. glumosa extract prevented significant (P<0.05) elevation in TC, LDL-c, VLDL-c, hepatic and aortic TG and TC. The atherogenic, triglyceride, and lipid peroxidation (TBARS) indexes were also decreased in the rats treated with the extract. F. glumosa favored the performance of fecal cholesterol. It also significantly inhibited the changes and the formation of aortic atherosclerotic plaques. These results revealed the hypolipidemic and antiatherosclerotic effects of F. glumosa extract and support the traditional use of the extract of this plant in the treatment of hypertension and diabetes.

Chemical composition, functional and sensory characteristics of wheat-taro composite flours and biscuits.

The physicochemical, alveographic and sensory characteristics of precooked taro-wheat composite flours and their biscuits were investigated. A 2x7 factorial design consisting of two varieties of taro flour (Red Ibo Ngaoundere, RIN, and egg-like varieties) and 7 levels of wheat substitutions (0, 5, 10, 15, 20, 25 and 30 %) was used for this purpose. It was observed that water absorption capacity (range 95-152 g/100 g), water solubility index (range 18.8-29.5 g/100 g) and swelling capacity (range 125.4-204.6 mL/100 g) of composite flours significantly (p < 0.05) increased with increase in taro level. Conversely the dough elasticity index (range 59.8-0 %), extensibility (78-22 mm) and strength (range 281-139 × 10(-4) joules) significantly (p < 0.05) diminished with increase in wheat substitution. Up to 10 % substitution with RIN taro flour and 15 % with egg-like taro flour, the composite taro-wheat dough exhibited elasticity indices acceptable for the production of baking products, whereas at all levels of taro substitution, the composite biscuits samples were either acceptable as or better (5-10 % substitution with RIN flour) than 100 % wheat biscuit.