Glycaemic index of different coconut (Cocos nucifera)-flour products in normal and diabetic subjects

Physicochemical characterization and fatty acid profiles of testa oils from various coconut (Cocos nucifera L.) genotypes

BACKGROUND

Cocos nucifera (L.) is an important plantation crop with immense but untapped nutraceutical potential. Despite its bioactive potential, the biochemical features of testa oils of various coconut genotypes are poorly understood. Hence, in this study, the physicochemical characteristics of testa oils extracted from six coconut genotypes - namely West Coast Tall (WCT), Federated Malay States Tall (FMST), Chowghat Orange Dwarf (COD), Malayan Yellow Dwarf (MYD), and two Dwarf × Dwarf (D × D hybrids) viz., Cameroon Red Dwarf (CRD) × Ganga Bondam Green Dwarf (GBGD) and MYD × Chowghat Green Dwarf (CGD) - were analyzed.

RESULTS

The proportion of testa in the nuts (fruits) (1.29-3.42%), the proportion of oil in the testa (40.97-50.56%), and biochemical components in testa oils - namely proxidant elements Fe (34.17-62.48 ppm) and Cu (1.63-2.77 ppm), and the total phenolic content (6.84-8.67 mg GAE/100 g), and phytosterol content (54.66-137.73 mg CE/100 g) varied depending on the coconut genotypes. The saturated fatty acid content of testa oils (67.75 to 78.78%) was lower in comparison with that of coconut kernel oils. Similarly, the lauric acid (26.66-32.04%), myristic (18.31-19.60%), and palmitic acid (13.43-15.71%,) content of testa oils varied significantly in comparison with the coconut kernel oils (32-51%, 17-21% and 6.9-14%, respectively). Liquid chromatography-mass spectrometry (LC-MS) analysis revealed the presence of 18 phenolic acids in coconut testa oil. Multivariate analysis revealed the biochemical attributes that defined the principal components loadings. Hierarchical clustering analysis of the genotypes showed two distinct clusters.

CONCLUSION

This study reveals the genotypic variations in the nutritionally important biochemical components of coconut testa oils. The relatively high concentration of polyunsaturated fatty acids (PUFA) and polyphenol content in testa oils warrant further investigation to explore their nutraceutical potential. © 2022 Society of Chemical Industry.

Physical, Chemical and Functional Attributes of Neera Honey Infused Extrudates

Owing to the demand for the consumption of healthy extrudates, this study explored the infusion of neera (coconut inflorescence sap) honey in rice flour, corn flour and coconut milk residue blend-based extrudates. Neera honey, the concentrated coconut inflorescence sap, has numerous nutrients and a natural source of essential vitamins. Hence, the potential of neera honey as a biofortifying compound for the production of healthy extrudates was investigated. The rice and corn based extrudates supplemented with different concentration of neera honey have been prepared until the mix reaches 16 and 20% (w.b.) of feed moisture. Effect of addition of neera honey on the physical properties (expansion ratio, bulk density, specific length), functional properties (water absorption, water solubility, oil absorption), biochemical properties (total carbohydrates, total sugar, reducing sugar, phenolics, flavonoids, antioxidants), color parameters(L*, a*, b*), proximate compositions (moisture content, ash, protein, fat) and mineral profile of extrudates were recorded. Results suggest that addition of neera honey had a significant (p ˂ 0.05) impact on all the physico-chemical parameters evaluated. Incorporation of neera honey (feed moisture -20%) resulted in extrudates with less expansion, high bulk density and specific length, having high sugar, protein, phenolics, vitamin C and antioxidant activity. The combination of 60% rice flour + 25% corn flour +15% coconut milk residue samples infused with neera honey upto 16% feed moisture was found suitable for the preparation of nutritious extrudates based on functional characterization and minerals evaluation.

Nutritional Profiles, Phytochemical Analysis, Antioxidant Activity and DNA Damage Protection of Makapuno Derived from Thai Aromatic Coconut

Makapuno is a natural mutant coconut cultivar with jelly-like endosperm. Here, we investigated the nutritional compositions, active ingredients, and antioxidant activities of Makapuno meat and water. The contents of macronutrients, sugars, vitamins, amino acids, and fatty acids were reported. We found that Makapuno meat has higher dietary fiber with lower protein and fat content compared to normal coconut meat. Medium-chain fatty acids were the major fat component of Makapuno meat and water. Phytochemical analysis revealed that while flavonoid content was lower, the total phenolic, alkaloid, and tannin contents of Makapuno meat were comparable with those of mature coconut. However, Makapuno water contained higher alkaloid content when compared to mature and young coconuts. The antioxidant activities, as examined by DPPH, FRAP, and ABTS assays, showed that Makapuno meat and water had antioxidant activities, and Makapuno water exhibited protective activity against DNA damage. Hence, this research provides the nutraceutical importance of Makapuno, which could be used in the food industry.

A glycaemic index compendium of non-western foods

Current international tables published on the glycaemic index (GI) of foods represent valuable resources for researchers and clinicians. However, the vast majority of published GI values are of Western origin, notably European, Australian and North American. Since these tables focus on Western foods with minimal inclusion of other foods from non-Western countries, their application is of limited global use. The objective of this review is to provide the GI values for a variety of foods that are consumed in non-Western countries. Our review extends and expands on the current GI tables in an attempt to widen its application in many other regions of the world.

Glycemic Index, Starch, and Protein Digestibility in Tempeh Gembus Cookies

Diabetes mellitus is directly related to diet and lifestyle. Control of blood glucose levels is needed to reduce the risk of complications, and one way is to choose foods with a low glycemic index. Cookies made from tempeh gembus/tempeh gembus flour are expected to be eaten as a snack and are safe for people with diabetes. The aim of this research was to analyze glycemic index (GI), glycemic load (GL), dietary fiber, in vitro starch, and protein digestibility of cookies with tempeh gembus flour substitution. Completely randomized design research with one primary factor used cookies with variations of 0%, 25%, and 50% tempeh gembus flour substitution. GI was calculated using the Incremental Area Under the Blood Glucose Response Curve (IAUC) method. Dietary fiber concentration analysis was done by enzymatic methods. The starch and protein digestion rates were calculated using the in vitro method. GI, GL, dietary fiber, starch digestion rate, and protein digestion rate data were analyzed with descriptive methods. Cookies with lowest GI (47.01 ± 11.08%) and GL (6.90 ± 1.63) were found in cookies with 50% tempeh gembus flour substitution. The highest dietary fiber content (24.61 ± 0.41%), digestibility of starch (48.07 ± 0.01%), and protein (20.27 ± 0.43%) cookies were found in cookies with 50% tempeh gembus flour substitution. The higher tempeh gembus flour substitution produced low GI and GL while its dietary fiber, in vitro starch, and protein digestibility were highest.

Coconut meal: Nutraceutical importance and food industry application

In tropical regions coconut is the tree of great significance: it provides millions of people with food, employment, and business opportunities. The fruit is referred to as ‘miracle fruit’ due to its inherent rich profile of macro- and micro-nutrients for human nutrition and health. Different products, such as coconut water, milk, raw kernels, oil and desiccated coconut are commercially processed. Coconut flour is a byproduct of coconut milk and oil industry which is made from coconut meal leftover after processing. Being a rich source of dietary fibre and protein, it has found numerous applications in different functional foods. Coconut flour can be successfully incorporated into various food products, such as bakery, extruded products, snacks, and sweets. It has antidiabetic and anticancer effects, prevents cardiovascular diseases, and improves immune function. Coconut flour is also gluten-free and its nutritional composition is quite comparable to that of wheat flour. Gluten-free food products enriched with coconut flour are a healthy and viable option for the people with celiac disease. In this paper, we summarised the present use of coconut flour. There is an apparent need to convert the food processing byproducts into functional ingredients in order to implement their environment-friendly and efficient utilisation.

Glycaemic index and glycaemic load values of commonly consumed foods in the United Arab Emirates

Glycaemic index (GI) and glycaemic load (GL) values of some commonly consumed foods in the United Arab Emirates were determined with an aim of adding these values to the existing international table of GI and GL values. In all, eighteen test foods categorised into breads (n 5), entrée dishes (n 3), main dishes (n 5) and sweet dishes (n 5) were tested. For each test food, at least fifteen healthy participants consumed 25 or 50 g available carbohydrate portions of a reference food (glucose), which was tested three times, and a test food after an overnight fast, was tested once, on separate occasions. Capillary blood samples were obtained by finger-prick and blood glucose was measured using clinical chemistry analyser. A fasting blood sample was obtained at baseline and before consumption of test foods. Additional blood samples were obtained at 15, 30, 45, 60, 90 and 120 min after the consumption of each test food. The GI value of each test food was calculated as the percentage of the incremental area under the blood glucose curve (IAUC) for the test food of each participant divided by the average IAUC for the reference food of the same participant. The GI values of tested foods ranged from low (55 or less) to high (70 or more). The GI values of various breads and rice-containing dishes were comparable with previously published values. This study provides GI and GL values of previously untested traditional Emirati foods which could provide a useful guide on dietary recommendations for the Emirati population.

Medicinal plants used in the traditional management of diabetes and its sequelae in Central America: A review

ETHNOPHARMACOLOGICAL RELEVANCE

Globally 387 million people currently have diabetes and it is projected that this condition will be the 7th leading cause of death worldwide by 2030. As of 2012, its total prevalence in Central America (8.5%) was greater than the prevalence in most Latin American countries and the population of this region widely use herbal medicine. The aim of this study is to review the medicinal plants used to treat diabetes and its sequelae in seven Central American countries: Belize, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua and Panama.

MATERIALS AND METHODS

We conducted a literature review and extracted from primary sources the plant use reports in traditional remedies that matched one of the following disease categories: diabetes mellitus, kidney disease, urinary problems, skin diseases and infections, cardiovascular disease, sexual dysfunctions, visual loss, and nerve damage. Use reports were entered in a database and data were analysed in terms of the highest number of use reports for diabetes management and for the different sequelae. We also examined the scientific evidence that might support the local uses of the most reported species.

RESULTS

Out of 535 identified species used to manage diabetes and its sequelae, 104 species are used to manage diabetes and we found in vitro and in vivo preclinical experimental evidence of hypoglycaemic effect for 16 of the 20 species reported by at least two sources. However, only seven of these species are reported in more than 3 studies: Momordica charantia L., Neurolaena lobata (L.) R. Br. ex Cass., Tecoma stans (L.) Juss. ex Kunth, Persea americana Mill., Psidium guajava L., Anacardium occidentale L. and Hamelia patens Jacq. Several of the species that are used to manage diabetes in Central America are also used to treat conditions that may arise as its consequence such as kidney disease, urinary problems and skin conditions.

CONCLUSION

This review provides an overview of the medicinal plants used to manage diabetes and its sequelae in Central America and of the current scientific knowledge that might explain their traditional use. In Central America a large number of medicinal plants are used to treat this condition and its sequelae, although relatively few species are widely used across the region. For the species used to manage diabetes, there is variation in the availability and quality of pharmacological, chemical and clinical studies to explain traditional use.

Effect of virgin coconut meal (VCM) on the rheological, micro-structure and baking properties of cake and batter

Virgin coconut meal (VCM) cakes were prepared by replacing refined wheat flour (maida) (5 to 20 % level) to check its effect on chemical, textural and rheological attributes of cake. The addition of VCM significantly (p ≤ 0.05) increased redness (a*), yellowness (b*) while reduced lightness (L*) of cakes. The incorporation of VCM affects the hardness, adhesiveness gumminess and chewiness of cake. The effect of flour replacement with VCM increased the viscosity of batter which leads to increase in consistency index and lower the shearthining behavior. The viscoelastic behavior of cake batter in which elastic modulus (G') and viscous modulus (G") both were decreased with the increase in percentage of VCM. The differential scanning calorimetry (DSC) analysis revealed that the onset (To), end set (Tc) and enthalpy of gelatinization (ΔH) increased with the increased level of VCM.

The effect of apparent amylose content and dietary fibre on the glycemic response of different varieties of cooked milled and brown rice

Brown rice is a good source of dietary fibre (DF) and contains higher vitamins/minerals than milled rice. The study determined the effect of amylose content (AC) and DF on glucose response (GR) from different varieties of milled and brown rice. Milled and brown rice were used as test foods. They were fed to 9-10 human volunteers containing 50 g available carbohydrate after an overnight fast. GR and the glycemic index (GI) were determined. Results found that Sinandomeng with the lowest AC had a high GI = 75, while PSBRc10 with the highest AC had a low GI = 50. Sinandomeng with a low DF had GI = 75, while its brown rice had GI = 55. Brown rice (IR64) with 23% AC and DF of 2.5 g/100 g had low GI = 51. In conclusion, the GR and GI of the different varieties of cooked milled and brown rice varied depending on its AC and DF contents.

Evaluation of antihyperglycemic activity of Cocos nucifera Linn. on streptozotocin induced type 2 diabetic rats

ETHNOPHARMACOLOGICAL RELEVANCE

The plant Cocos nucifera Linn. (Arecaceae) is commonly known as coconut. Traditionally the juice of the young spadix when fresh is used in diarrhea and diabetes. The objective of the present study was to investigate the effect of antidiabetic activity and effect on lipid profile as well as cardioprotective effect of hydro-methanol extract of Cocos nucifera (HECN) on streptozotocin (STZ)-induced diabetic rats.

MATERIALS AND METHODS

After 72 h of STZ (50 mg/kg, b.w. i.p.) administration, animals showing plasma sugar level more than 250 mg/dl were considered as diabetic rat. Fasting blood glucose (FBG) levels were measured on 0th (after 72 h of STZ), 5th, 10th, and 15th day. On the 15th day all the animals were sacrificed and the serum biochemical parameters and antioxidant enzyme status were measured.

RESULTS

HECN treated animals showed a significant reduction in FBG level as compared with diabetic control group. Serum enzyme level (SGOT, SGPT, SALP), lipid peroxidation and antioxidant enzyme level such as CAT, GSH, SOD and cholesterol and triglycerides in the HECN treated groups were restored towards normal level as compared to diabetic control groups and the values were comparable with the standard groups (glibenclamide).

CONCLUSION

Improvement in the FBG and the restoration of all other biomarker as well as enzymes indicates that HECN has very good antidiabetic activity with very low side effects and provides a scientific rationale for the use as an antidiabetic agent.

Glycemia and peak incremental indices of six popular fruits in Taiwan: healthy and Type 2 diabetes subjects compared

The aim of this study was to evaluate the glycemic index and peak incremental indices of six popular fruits in Taiwan, comparing healthy subjects (n = 20) and patients with Type 2 diabetes (n = 17). The six kinds of fruits tested were grapes, Asian pears, guavas, golden kiwifruit, lychees and bananas. Glycemic index values were tested according to the standard glycemic index testing protocol. The glycemic index and peak incremental indices were calculated according to published formulas. In Type 2 diabetes subjects, the glycemic index values of grapes, Asian pears, guavas, golden kiwifruit, lychees and bananas were 49.0 ± 4.5, 25.9 ± 2.9, 32.8 ± 5.2, 47.0 ± 6.5, 60.0 ± 8.0 and 41.3 ± 3.5. In healthy subjects, the glycemic index values were 49.1 ± 7.3, 18.0 ± 5.4, 31.1 ± 5.1, 47.3 ± 12.1, 47.9 ± 6.8 and 35.1 ± 5.6. There was no significant difference in glycemic index values between healthy and Type 2 diabetes subjects. There was also no significant difference in PII when comparing healthy subjects and subjects with Type 2 diabetes. In conclusion, glycemic index and peak incremental indices in healthy subjects can be approximately the same for Type 2 diabetes.

Relationship between Processing Method and the Glycemic Indices of Ten Sweet Potato (Ipomoea batatas) Cultivars Commonly Consumed in Jamaica

This study investigated the effect of different traditional cooking methods on glycemic index (GI) and glycemic response of ten Sweet potato (Ipomoea batatas) cultivars commonly eaten in Jamaica. Matured tubers were cooked by roasting, baking, frying, or boiling then immediately consumed by the ten nondiabetic test subjects (5 males and 5 females; mean age of 27 ± 2 years). The GI varied between 41 ± 5-93 ± 5 for the tubers studied. Samples prepared by boiling had the lowest GI (41 ± 5-50 ± 3), while those processed by baking (82 ± 3-94 ± 3) and roasting (79 ± 4-93 ± 2) had the highest GI values. The study indicates that the glycemic index of Jamaican sweet potatoes varies significantly with the method of preparation and to a lesser extent on intravarietal differences. Consumption of boiled sweet potatoes could minimize postprandial blood glucose spikes and therefore, may prove to be more efficacious in the management of type 2 diabetes mellitus.

Glycaemic response to quality protein maize grits

Background. Carbohydrates have varied rates of digestion and absorption that induces different hormonal and metabolic responses in the body. Given the abundance of carbohydrate sources in the Philippines, the determination of the glycaemic index (GI) of local foods may prove beneficial in promoting health and decreasing the risk of diabetes in the country. Methods. The GI of Quality Protein Maize (QPM) grits, milled rice, and the mixture of these two food items were determined in ten female subjects. Using a randomized crossover design, the control bread and three test foods were given on separate occasions after an overnight fast. Blood samples were collected through finger prick at time intervals of 0, 15, 30, 45, 60, 90, and 120 min and analyzed for glucose concentrations. Results. The computed incremental area under the glucose response curve (IAUC) varies significantly across test foods (P < .0379) with the pure QPM grits yielding the lowest IAUC relative to the control by 46.38. Resulting GI values of the test foods (bootstrapped) were 80.36 (SEM 14.24), 119.78 (SEM 18.81), and 93.17 (SEM 27.27) for pure QPM grits, milled rice, and rice-QPM grits mixture, respectively. Conclusion. Pure QPM corn grits has a lower glycaemic response compared to milled rice and the rice-corn grits mixture, which may be related in part to differences in their dietary fibre composition and physicochemical characteristics. Pure QPM corn grits may be a more health beneficial food for diabetic and hyperlipidemic individuals.

Carbohydrate-rich foods: glycaemic indices and the effect of constituent macronutrients

The glycaemic index (GI) ranks foods according to their acute glycaemic impact and is used in planning meals for patients invoking glycaemic control through diet. Kurakkan (Eleusine coracana) flour roti, rice flour roti, atta flour roti, boiled breadfruit (Artocarpus altilis/Artocarpus communis) and boiled legumes (mungbean, cowpea and chickpea) were categorized as low-GI foods (relative to white bread; Prima Crust Top), and the corresponding GI (+/- standard error of the mean) values were 70+/-8, 69+/-7, 67+/-9, 64+/-7, 57+/-6, 49+/-8 and 29+/-5, respectively. Kurakkan flour pittu and wheat flour roti were classified as medium-GI foods with GI values of 85+/-6 and 72+/-6. Hoppers, rice flour pittu, wheat flour pittu and Olu-milk rice (seeds of Nymphaea lotus) were categorized as high-GI foods, and the corresponding GI (+/- standard error of the mean) values were 120+/-8, 103+/-7, 101+/-8 and 91+/-8, respectively. The GI values significantly (P<0.01) and negatively correlated with the insoluble dietary fibre (rho = - 0.780), soluble dietary fibre (rho = - 0.712) and protein (rho = - 0.738) contents in grams per 100 g digestible starch containing foods.

The potential health benefits of legumes as a good source of dietary fibre

Dietary fibre has been shown to have important health implications in the prevention of risks of chronic diseases. The objective of the present study was to determine the potential health benefits of legumes as a good source of dietary fibre. Six to ten local legumes were studied as follows: cowpeas, mung beans, pole sitao, chickpeas, green peas, groundnuts, pigeon peas, kidney beans, lima beans and soyabeans. The following studies were conducted: (a) mineral availability, in vitro; (b) glycaemic index (GI) in non-diabetic and diabetic human subjects; (c) the cholesterol-lowering effect in human subjects with moderately raised serum cholesterol levels. The highest Fe availability among legumes was for lima beans (9·5 (sem 0·1)) while for Zn and Ca, the highest availability was for kidney beans (49·3 (sem 4·5)) and pigeon peas (75·1 (sem 7·1)), respectively. Groundnuts have the lowest Fe (1·3 (sem 1·1)), Zn (7·9 (sem 1·3)) and Ca (14·6 (sem 2·8)) availability. Legumes are low-GI foods ( < 55), ranging from 6 (chickpeas) to 13 (mung beans). Kidney beans showed significant reductions for both total (6 %) and LDL-cholesterol (9 %), and groundnuts for total cholesterol (7 %; P < 0·05). We conclude that mineral availability from legumes differs and may be attributed to their mineral content, mineral–mineral interaction and from their phytic and tannic acid content; legumes are considered low-GI foods and have shown potential hypocholesterolaemic effects. The above studies can be a scientific basis for considering legumes as functional foods.

The Cholesterol-Lowering Effect of Coconut Flakes in Humans with Moderately Raised Serum Cholesterol

This study investigated the effect of coconut flakes on serum cholesterol levels of humans with moderately raised serum cholesterol in 21 subjects. The serum total cholesterol of subjects differed and ranged from 259 to 283 mg/dL. The study was conducted in a double-blind randomized crossover design on a 14-week period, consisting of four 2-week experimental periods, with each experimental period separated by a 2-week washout period. The test foods were as follows: corn flakes as the control food, oat bran flakes as the reference food, and corn flakes with 15% and 25% dietary fiber from coconut flakes (made from coconut flour production). Results showed a significant percent reduction in serum total and low-density lipoprotein (LDL) cholesterol (in mg/dL) for all test foods, except for corn flakes, as follows: oat bran flakes, 8.4 +/- 1.4 and 8.8 +/- 6.0, respectively; 15% coconut flakes, 6.9 +/- 1.1 and 11.0 +/- 4.0, respectively; and 25% coconut flakes, 10.8 +/- 1.3 and 9.2 +/- 5.4, respectively. Serum triglycerides were significantly reduced for all test foods: corn flakes, 14.5 +/- 6.3%; oat bran flakes, 22.7 +/- 2.9%; 15% coconut flakes, 19.3 +/- 5.7%; and 25% coconut flakes, 21.8 +/- 6.0%. Only 60% of the subjects were considered for serum triglycerides reduction (serum triglycerides >170 mg/dL). In conclusion, both 15% and 25% coconut flakes reduced serum total and LDL cholesterol and serum triglycerides of humans with moderately raised serum cholesterol levels. Coconut flour is a good source of both soluble and insoluble dietary fiber, and both types of fiber may have significant role in the reduction of the above lipid biomarker. To our knowledge, this is the first study conducted to show a relationship between dietary fiber from a coconut by-product and a lipid biomarker. Results from this study serves as a good basis in the development of coconut flakes/flour as a functional food, justifying the increased production of coconut and coconut by-products.