Nutrient composition and functional properties: Suitability of flour of sweet potatoes (Ipomea batatas) for incorporation into food production

Sweet potatoes are effortlessly grown and high yielding food crop. However, these are considered as underutilized produce with limited incorporation into food industry. Hence the objectives of this study were to determine the nutrient composition and functional properties of twelve (12) sweet potato varieties available in Sri Lanka to study the potential to be incorporated into food production. The varieties analysed were Ama, Dhawala, Wariyapola White, Wariyapola Red, Shanthi, Hordi Malee, CARI 09, CARI 273, Ranabima, Gannoruwa White, Chithra and Makandura Purple. Determination of moisture, ash, crude protein, crude fat, dietary fiber (soluble/insoluble), carbohydrates and functional properties were by standard methods. Ash, crude fat and crude protein contents comprised less than 7% (dry matter; DM) with total carbohydrate content varying between 49-80% DM in studied sweet potatoes. Total dietary fiber comprises approximately 8.5% (DM) with the highest proportion being insoluble dietary fiber. Functional properties resulted a swelling capacity of 15-27 mL with high oil absorption capacity (120-220%), emulsion activity (42-48%) and stability (above 35%), and bulking density (0.62-0.95 g/cc) with least gelation concentration of 18-30%. The results prove the ability of the studied sweet potato flours to be incorporated in composite flour mixtures and novel food products

Free radical Scavenging Activity and Phenolic content of decoctions of some medicinal plants

Free radicals are normally generated in substantial amounts in the body; excessive amounts cause oxidative damage through chain reactions forming disorders like diabetes mellitus, cardiovascular and pulmonary diseases. In diabetic conditions, a non enzymatic reaction occurs with proteins and reducing sugars forming glycated protein named Amadori products. Further rearrangement, oxidation and reduction of Amadori products leads to form Advanced Glycated End products which causing spontaneous damage to proteins in physiological system leading various complications like Nephropathy, Neuropathy ,Retinopathy and this process accompanying the formation of free radicals. In this process oxidation plays an important role to form Advanced Glycated End Products. Therefore antioxidants are highly important in prevention or slowing the glycation reaction. Humans have evolved a complex antioxidant system, but this may not be sufficient to maintain optimal cellular functions in diabetic conditions. Medicinal plants usually contain different phenolic compounds having antioxidant properties. Therefore, a study was carried out to examine the in vitro free radical scavenging activity and total phenolic content of the decoctions of plants, Cassia auriculata (Ranawara, flower) Phyllanthus emblica (Nelli, fruit) and Scoparia dulcis (Walkottamalli, whole plant) which are used in the treatment for diabetics. Three fresh samples from each plant collected from different areas where they are grown and commercial dried sample from the traditional market was selected to prepare the decoctions and compared phenolic contents and antioxidant activity. The total phenolic content of each extract was determined using Folin-Ciocalteu reagent and evaluation of free radical scavenging activity was assessed using DPPH assay and ABTS assay. Decoctions of the commercial samples of P. emblica showed the highest total phenolic content as 625 mgGAE/g and C auriculata and S dulcis showed 459 and 131 mgGAE/g respectively. Samples dried under laboratory conditions of C.auriculata had total phenolic content from 226 – 287 mgGAE/g, P.emblica from 479 -517 mgGAE/g and S dulcis from 167 – 186 mgGAE/g. The highest DPPH antioxidant activity showed the commercial sample of P. emblica as 27 μg/ml and other samples dried under laboratory conditions were in the range of 41 – 49 μg/ml. No significant difference between the DPPH activity of C. auriculata commercial sample and other samples dried in the dehydrator and were in the range of 248 -309 μg/ml while S. dulcis all the samples showed DPPH antioxidant activity from 437 – 540 μg/ml. The reference standard, Butylated Hydroxy Toluene showed 20 μg/ml. ABTS antioxidant activity was high in all commercial samples of C.auriculata, P.emblica and S. dulcis and were as 648,625 and 615 mmol/g while other samples dried using the dehydrator showed 313 – 536 mmol/g,479 -517 mmol/g and 549-550 mmol/g respectively.Key words: Antioxidant properties, Glycation, Diabetes, DPPH assay, ABTS assa

Protein quality of foods made incorporating Cycas circinalis seed flour

Among the cycad species Cycas circinalis and Cycas zeylanica are native to Sri Lanka. Foods such as pittu and roti made by incorporating Cycas circinalis seed flour are consumed by Sri Lankans living in areas where the plant grows. Although previously reported data indicate that the content of protein in C. circinalis seeds is comparable to that of wheat flour, no data is available on the quality of cycad seed proteins. The present study was aimed at evaluating the quality of proteins in C. circinalis seed flour, pittu and roti made by incorporating cycas seed flour.The moisture, insoluble (IDF) and soluble dietary fibres (SDF), crude protein and digestible carbohydrate contents were measured by AOAC official methods (1984), method of Asp et al, Lowry’s method/ Folin Ceocalteau method and Holm’s method respectively. Quality of proteins was estimated by AOAC Official method 960.48, using an animal bioassay.Digestible carbohydrate content was highest in soaked seed flour (50.0±2.03). Among the cycad foods, highest protein content (10.3±0.01) and total dietary fibre content (7.7) were in roti and this could be due to the addition of wheat flour to roti instead of rice flour in pittu. Highest weight gain was observed in reference group fed with casein containing diet. The significantly high weight gain in the seed flour fed group compared to roti and pittu fed groups may be due to the high feed intake. No significant weight gain difference was observed between roti and pittu fed groups. Protein quality of C. circinalis seeds was comparable with that of common maize but all protein quality parameters [Protein Efficiency Ratio (PER), Food Efficiency Ratio (FER), Net Protein Retention (NPR) and Protein Retention Efficiency (PRE)] were significantly low compared to the reference protein diet. Although not significant, NPR and PRE values in roti (1.4±0.6 and 8.5±3.7) were higher than test food made with pittu or raw seed flour.Key words: protein quality, Protein Efficiency Ratio (PER), Food Efficiency Ratio (FER), Net Protein Retention (NPR) and Protein Retention Efficiency (PRE

Acute postprandial gut hormone, leptin, glucose and insulin responses to resistant starch in obese children: a single blind crossover study

Introduction: Resistant starch (RS) has beneficial effects on postprandial glucose metabolism in both animals and adults. Hitherto, there have been no studies in children of the acute metabolic and hormonal effects of RS-containing meals. Objectives: We aimed to compare serial plasma glucose, insulin, gut hormone, leptin profiles and satiety scores in obese children after meals containing variable amounts of RS. Methods: This was a single blind, non-randomised, crossover study of 20 obese children aged 10–14 years old without comorbidities. Three test meals containing rice (M1), rice cooked with coconut oil (M2), rice cooked in coconut oil with lentils (M3) were given in sequence after a 12-hour fast . Blood samples were analysed for glucose (PG), insulin, leptin, glucagon-like polypeptide (GLP) 1, ghrelin and peptide YY (PYY) at appropriate times between 0 and 180 min. Results: Meal M2 resulted in significantly lower postprandial glucose values compared with meal M1 (maximal incremental glucose, ∆Cmax, p<0.05; area under the curve, ∆AUC0–3, p<0.01) and meal M3 (maximal concentration, Cmax, p<0.01; ∆Cmax, p<0.001, and ∆AUC0–3p<0.01). M2 also produced lower insulin values compared with M1 (p<0.05). Postprandial ghrelin was significantly higher after M1 compared with M3 (p<0.05). PYY, GLP1 and median satiety scores were not significantly different between the three meals. Conclusion: This study shows that M2, the meal containing RS alone, induced beneficial effects on acute postprandial glucose, insulin and ghrelin concentrations in obese children without diabetes. Acute postprandial satiety scores were not significantly affected by the three meals. Trial registration number: SLCTR/2020/007

Potential of Canavalia gladiata as a food ingredient: Nutritional and Functional aspects

The tender fruits of the leguminous plant Canavalia gladiata (Sinhala awara, sword beans) are consumed in Sri Lanka as a green vegetable. The mature seeds are also utilized in a variety of ways but not very frequently, in spite of desirable agronomical properties, for cultivation in the country. This study was performed with the intention of developing methods for increasing utilization of the sword bean for human consumption. Flour of the whole mature seed and cotyledon contained higher crude protein than other legumes, with starch as the major nutrient. The total dietary fibre of whole seed was thrice the amount in cotyledon. Sucrose represents the highest fraction of low molecular weight carbohydrates in both types of flour. In comparison with the recommended dietary intake for adults the seeds contained K, Mg and P in considerable quantities. The essential amino acid profile compared well with the FAO/WHO recommended pattern except for the sulphur-containing amino acids. Heat processing increased the true digestibility of the cotyledon grits and flour when compared to raw and soaked grits. Soaking decreased the digestibility of cooked or uncooked seeds. The biological value of the processed samples was lower than that of raw sample except for soaked and cooked grits. The NPU values of (i) cooked and (ii) soaked and cooked grits were higher than those of other heat-processed samples, and also of raw seed flour, while not different from each other. The correlation between the in vivo and in vitro digestibility values was poor suggesting that the in vitro method was not a good predictor of changes in in vivo digestibility due to processing. Starch granules were elliptical in shape. A well-defined cross, typical of ungelatinized starch, was seen under polarized light in raw and dry-heat treated samples. Wet-processed samples had lower water solubility, higher water absorption and lower gelatinization enthalpies than the raw bean flour, whereas the dry-heat-treated samples showed higher water solubility and higher gelatinization enthalpies. The starch molecular size distribution pattern indicated a higher amount of high molecular weight carbohydrates in dry heat-treated samples and a large fraction of intermediate molecular weight carbohydrates in the wet-processed samples. The low molecular weight carbohydrate content was low in wet-processed samples. The content of canavanine, a potentially toxic amino acid, was quantified successfully using HPLC. The highest decrease in canavanine content was seen when soaked overnight and boiled in excess water followed by decanting. Boiling and decanting excess water was the other effective processing method for reducing canavanine. Roasting and autoclaving were less effective in decreasing the canavanine content. The chemical composition and the protein nutritional quality evaluation indicate sword beans to be a good complement to be introduced as a new food to a cereal-based diet. The decrease in canavanine content was highest in wet-processed samples. The decorticated seed grits once soaked and cooked or cooked would have the best nutritional quality and the lowest anti-nutritional factors and thus could be used as a thickener in food preparations or be incorporated into dough

Canavanine content of sword beans (Canavalia gladiata) – analysis and effect of processing

The amino acid canavanine is a potentially toxic constituent of leguminous seeds. The aim of the present study was to determine the ability of different processing methods to reduce canavanine in sword beans (Canavalia gladiata). For this purpose a method for the detection and quantification of canavanine was developed using reversed-phase high-performance liquid chromatography of the dabsylated derivatives. The recovery of canavanine using this method was 88–91%. Optimum extraction of canavanine from raw and processed beans was obtained by addition of hot water prior to overnight soaking. The results obtained with this method agree well with previously published values for raw seeds. The method is sensitive, specific and can successfully be applied to the detection of canavanine in legumes. Overnight soaking and boiling in excess water followed by decanting gave the most pronounced reduction in canavanine content (around 50%), followed by boiling and decanting excess water (34%). Roasting as used in this study and autoclaving were less effective in reducing the canavanine content

Dietary Habits of Type 2 Diabetes Patients: Variety and Frequency of Food Intake

The objective of the present study was to observe the dietary patterns and food frequencies of type 2 diabetes patients attending the clinics of the Family Practice Center of the University of Sri Jayewardenepura, located in a highly urbanized area in Sri Lanka. An interviewer administered questionnaire based cross-sectional study was conducted among randomly selected 100 type 2 diabetes patients [age 35–70 years; mean age 55±9 (males = 44; females = 56)]. The data were analyzed by SPSS version 18.0 software. Vegetables, fatty foods, and poultry consumption were in accordance with the national guidelines. A significant percentage (45.5%) consumed rice mixed meals for all three meals and only 67% consumed fruits at least once a day. Majority (71%) consumed full-cream milk and sugar intake (77%) was in accordance with the guidelines. Noncaloric sweetener usage was nonexistent. Daily green leafy vegetable intake and the quantity consumed were inadequate to obtain beneficial effects. From the study population, 44% [females 50%; males 36%] of the patients were either overweight or obese. However, only 60% of those patients accepted that they were either overweight or obese. Only 14% exercised daily while 69% never exercised. Study revealed the importance of educating patients with type 2 diabetes on dietary changes and more importantly the involvement in regular physical exercises

Comparative analysis of nutrient composition and glycaemic indices of nine sweet potatoes (Ipomoea batatas) varieties

Sweet potatoes are one of the major tuberous roots consumed around the world. The objective of the present study was to determine the nutritional composition, glycaemic indices and glycaemic loads of selected Sri Lankan sweet potato varieties, in order to address the inadequacy of information and the controversial findings on glycaemic indices. Nutrient composition (moisture, ash, digestible carbohydrates, dietary fiber, crude protein and fat) of boiled sweet potatoes, GI and glycaemic loads (GL) of nine varieties were determined using standard methods. Digestible carbohydrate content ranged between 29-88% on dry weight. Ash, crude protein and crude fat contents of the varieties ranged between 3.1-5.0%, 3.0-5.9% and 2.6-5.3% on dry weight basis (DW) respectively. The total dietary fiber content was above 9.5% DW in the studied varieties. Moisture content of boiled sweet potato tubers were 72-81% on fresh weight basis and both the GIs (86-119) and GLs (&gt;20) were high. However, the GL reduced to medium or low when considering an actual edible portion for all the varieties except for two varieties. Sweet potatoes are a good source of highly available carbohydrates which elicit high GIs

Effects of Gymnema lactiferum leaves on glycemic and lipidemic status in type 2 diabetes subjects

Gymnema lactiferum var. lactiferum is a climber distributed in many South Asian countries. It is reported that the diabetic patients in Sri Lanka use G. lactiferum leaves as a treatment for diabetes. However, scientific data is not available on this plant. A clinical trial was conducted including 26, type 2 diabetic patients with hypercholesterolemia. The treatment group received a suspension of G.  lactiferum leaf powder twice daily for  four weeks. Blood parameters of both groups (treated and control) were determined at the beginning and the end of the study period. Study indicates significant effects on fasting blood sugar (p=0.002), cholesterol (p=0.004), and LDL lowering (p=0.023) and a significant postprandial glucose lowering effect (p=0.026 for 60 min and p=0.022 for 120 min, after four weeks). In spite of the short study period, a significant reduction (p=0.012) in HbA1C levels was also observed