Cliff K. Riley

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.

The interplay between yam (Dioscorea sp.) starch botanical source, micromeritics and functionality in paracetamol granules for reconstitution

A comparative investigation of the interplay between starch botanical source, micromeritics and their functionality in formulated paediatric paracetamol granules for reconstitution was conducted using starches extracted from five local yam (Dioscorea spp.) species. Significant differences were observed in the physicochemical properties of the different starches studied (p<0.05). The observed differences in paracetamol dissolution correlated well with the physicochemical properties of the starches. Granules formulated with Chinese yam and Bitter yam starches showed the fastest rate of paracetamol dissolution with T(80) of 2.2 and 2.6 min, respectively, at 2.5%w/w, and 3.75 and 4.00 min, respectively, at 10% w/w binder concentrations. Those formulated with Round leaf yellow yam starch had the slowest dissolution rate with T(80) of 4.5 and 8.75 min, respectively, at 2.5% and 10% binder concentrations. The results generally indicate a significant dependence of the rate of paracetamol dissolution from granules on starch surface tension, viscosity, swelling power and water binding capacity, particle size distribution, specific surface and porosity. These, in turn, were found to be starch botanic source-dependent suggesting careful consideration of botanic source when substituting one starch product for another in granule formulation.

Relationship between the physicochemical properties of starches and the glycemic indices of some Jamaican yams (Dioscorea spp.)

Starch granules from round leaf yellow yam (RY), Lucea yam (LY), white yam (WY), and Chinese yam (CY) grown in Jamaica were isolated and the relationship between starch amylose content, crystallinity, microscopic properties, in vitro digestibility, and the glycemic index (GI) of the tubers was investigated. The results indicate that RY had the highest amylose content (265.30 +/- 0.09 g/kg starch) while CY the lowest (111.44 +/- 0.03 g/kg starch). A corresponding variation in starch digestibility and GI was also observed, as CY which had the highest in vitro digestibility had the highest GI (21.27 +/- 0.01 and 97.42 +/- 0.62%, respectively), while RY, LY, and WY starches with low digestibility had lowest GI. Differences in the crystalline pattern of the different starches were observed, where RY, LY, and WY displayed the type B crystalline pattern while CY had the intermediate crystallite (type C).

High Fiber Caribbean Diets with Low-Intermediate GI Improve Glycemic Control, Cardiovascular and Inflammatory Indicators in Overweight Persons with Type 2 Diabetes: A Randomized Control Study

This study focused on the effect of consumption of indigenous Caribbean foods with low and intermediate glycemic index (GI) high fiber contents on glycated haemoglobin (A 1c), insulin, fasting blood glucose, homocysteine (tHCY), high sensitivity C-reactive protein (hs-CRP), homeostasis model assessment of Insulin Resistance (HOMA-IR) and lipoprotein profile levels in overweight persons with type 2 diabetes. The methodology followed a randomized controlled parallel design, which compared two dietary treatment modalities in adult Jamaicans who were overweight and diagnosed with type 2 diabetes (mean age 42.5 ± 2.0 years, 55% females, mean A1c 9.30 ± 0.56%) over six months. The intervention group (n=32) underlined the consumption of low-intermediate-GI foods, whereas the control group (n = 33) were not so advised and consumed a high-GI diet. Attempts were made to ensure that both groups were isocaloric with 45-50% of energy from carbohydrates. Consumption of low-intermediate GI foods resulted in significant reductions (p<0.005) in A 1C compared to participants who consumed high GI foods (-0.84 ± 0.26 vs. -0.35 ± 0.04%), hs-CRP (-0.52 ± 0.17 vs. -0.17 ± 0.31 mg/dL) and tHCY (-1.32 ± 0.39 vs. -0.59 ± 0.38 µmol/L). Insulin sensitivity, HDL-C and triglycerides significantly improved in participants who consumed the low-intermediate-GI diet. The data strengthen the metabolic benefits of meal plans that emphasize the consumption of low and intermediate GI high fiber foods, particularly, indigenous Caribbean complex starchy foods.