Starch Glycemic Index Research Articles

Properties of Vietnamese water caltrop starch and formation of low glycemic index starch

This research investigates the properties and modification of water caltrop starch (WCS) with a particular focus on its potential for retrogradation and resistance to enzymatic hydrolysis. The study begins by obtaining WCS with a recovery efficiency of 4.5% (w/w in dry basis). The native WCS exhibits notable characteristics, including an apparent amylose content of 45.4%, a ratio of amorphous/α-helix regions at 1.341, a degree of relative crystallinity of 54.43%, an average molecular weight of 6.58×104 g/mole, and a degree of polymerization of 365.57. The high amylose content and degree of crystallinity in native WCS indicate its favorable retrogradation potential and resistance to enzymatic hydrolysis. Textural analysis of the WCS gel reveals high hardness and chewiness but low adhesiveness, which further supports its potential for retrogradation applications. To explore the effects of repeated retrogradation cycles, native WCS was subjected to 3, 6, and 9 cycles. The increase in retrogradation cycles led to a decrease in apparent amylose content from 31.79% to 29.34%. This reduction can be attributed to the formation of double helix associations and the emergence of new crystalline regions from amylose molecules. Furthermore, an increase in retrogradation cycles resulted in enhanced syneresis of starch. Interestingly, as the number of retrogradation cycles increased, the enzymatic hydrolysis rate of retrograded WCS gradually decreased. Correspondingly, the estimated glycemic index (GI) of the samples decreased, reaching a range of 50.05 to 38.46. Consequently, treatment with repeated retrogradation proves to be an effective strategy for producing modified WCS with a low glycemic index (<50%), thereby presenting promising opportunities for low glycemic index applications.

Glycemic Index, Antioxidant Activity and Starch Composition of Various Varieties of Oryza sativa L (Rice) Available in Pakistan

The 10 samples of different rice were collected from Ashraf road firdos bazaar Peshawar and were tested for glycemic indices, total starch content, free radical scavenging activity, and amylose to amylopectin ratio. The glycemic indices were in the range of 72.88 ±1.70 to 89.08 ±6.19, and total starch content from 7 to 35.1%. The free radical scavenging activity of Basmati Chawal 18.46±0.33 (lowest) to Mota Chawal 44.98±2.02 (highest). The Amylose to Amylopectin ratio was from 0.12 to 1.822. The highest Amylose to Amylopectin ratio was of Seela Lazat (1.822) and the lowest one was of Seela Dakra Dobar (0.12). The sample of lowest glycemic index was Seela Dakra Dobar (72.88 ±1.70) and the highest was Mota Chawal (89.08 ±6.19). The DPPH method was followed for the measurement of antioxidant activity. The %inhibition of DPPH activity by an antioxidant was in the range of 18.46±0.33 to 44.98±2.02 for 100µg/ml. Conclusion: The research performed was to determine radical scavenging activity, Glycemic Index Starch content and Amylose to Amylopectin ratio for different rice varieties. A variety which has high radical scavenging activity, low Glycemic index and high Amylose Content will be a good variety to use to be healthier. That variety should be preferred for diabetic patient.

379 Effect of yeast fermentation on pea starch glycemic index in dogs.

379 Effect of yeast fermentation on pea starch glycemic index in dogs.

Metabolic and Hormonal Alterations with Diacylglycerol and Low Glycemic Index Starch during Canine Weight Loss

Obesity increases insulin resistance and disregulation of glucose homeostasis. This study investigated low glycemic index starch (LGIS)/diacylglycerol (DAG) diet on plasma insulin and circulating incretin hormones during canine weight loss. Obese Beagle dogs were fed one of four starch/oil combination diets (LGIS/DAG; LGIS/triacylglycerol (TAG); high glycemic index starch (HGIS)/DAG; and HGIS/TAG) for 9 weeks during the weight loss period. At weeks 1 and 8, fasting plasma insulin, glucose, nonesterified fatty acid (NEFA), glucose-dependent insulinotropic polypeptide (GIP), and glucagon-like peptide-1 (GLP-1) were determined. Weight loss did not affect fasting insulin, glucose, and NEFA, but fasting GIP increased and GLP-1 decreased. LGIS affected postprandial insulin at both times and glucose was similar to insulin, except 60 min postprandially with DAG at week 8. NEFA lowering was less with the LGIS diets initially but not thereafter. At 60 min postprandially on week 8, GIP was significantly elevated by DAG, while GLP-1 was increased only with the HD diet. LGIS suppressed insulin and glucose responses up to 180 min postprandially at both sample times. DAG increased incretin hormones as did the DAG/HGIS combination but only at week 8. This latter finding appeared to be related to the glucose response but not to insulin at 60 min.

Postprandial Lipid-Related Metabolites Are Altered in Dogs Fed Dietary Diacylglycerol and Low Glycemic Index Starch during Weight Loss1–3

In this study, we investigated a combination of a low glycemic index starch (LGIS) and diacylglycerol (DAG) on lipid, lipoprotein (LP) metabolism, and weight management. Obese, intact female adult Beagle dogs were assigned to 1 of 4 starch/oil combination diets [LGIS/DAG (LD); LGIS/triacylglycerol (TAG); high glycemic index starch (HGIS)/DAG; and HGIS/TAG (HT)] and fed for 9 wk (n = 6/group) using an incomplete 4 × 4 Latin square design. Each dog was fed 1 of 2 opposite starch/oil combination diets (e.g. LD and HT). At wk 1 and 8, postprandial blood was collected for plasma triacylglycerol (TG), β-hydroxybutyrate (BHB), total cholesterol (TC), and LP analyses. During the same week, dogs were overnight feed-deprived and post-heparin blood was collected for LP lipase and hepatic lipase activity determinations. At wk 1, 4, and 8, blood was drawn from overnight feed-deprived dogs for plasma TG, BHB, TC, LP, leptin, and adiponectin measurements. Feces were collected at wk 3 for digestibility calculations. The LGIS diets resulted in lower carbohydrate, protein, total tract dry matter digestibilities, and metabolizable energy compared with the HGIS diet groups (P < 0.05). Thus, the LGIS groups lost more body weight (P = 0.001), which was positively correlated with plasma leptin concentrations (r2 = 0.427; P < 0.001). Moreover, the LGIS diet lowered TC concentrations in combination with DAG. The DAG diet groups decreased postprandial TG and increased BHB concentrations (P < 0.05). Starch/oil types did not alter lipase activities or adiponectin concentrations. In conclusion, the LGIS diet demonstrated potential as a weight management tool in dogs by decreasing postprandial TG and increasing BHB in combination with DAG.

Plasma LCAT Activity and Lipid Subfraction Composition in Obese Beagles Undergoing Weight Loss

The relationship between lecithin:cholesterol acyltransferase (LCAT) activity and weight loss in dogs was investigated. Four experimental weight-loss diets were fed to 12 obese female beagles for 56 days in a partial crossover design (n = 6). High- (HGI) or low- (LGI) glycemic index starch and diacylglycerol or triacylglycerol oils were combined to compose experimental diets with similar fatty acid profiles. Food intake and body weights were measured daily and weekly, respectively. Fasted blood samples were drawn at day 0, day 28, and day 56 to measure plasma LCAT activity and total (TC), unesterified (UC), and esterified (EC) cholesterol concentrations, and for fatty acid analysis of the phospholipid (PL) and EC fractions. The LGI groups lost more weight than the HGI groups due to starch digestibility differences. An HGI starch effect on TC and UC concentrations was observed but was unrelated to weight loss. LCAT activities increased over time but were not different after controlling for percentage weight loss. However, a positive linear correlation was found between LCAT and UC concentrations in all groups. Plasma PL fatty acid profiles reflected the diets fed, but increases in 16 and 18 carbon saturated and monounsaturated fatty acids in all groups appeared to be an effect of fatty acid mobilization from storage sites. Both plasma PL and EC fatty acid profiles were similar with both acylglycerol types and EC fatty acids reflected linoleic acid specificity with minimal diet or time effects.

Development of a Low Glycemic Maize Starch: Preparation and Characterization

A low glycemic index starch was developed by partial alpha-amylase treatment, and its fine structure responsible for slowly digestible and resistant properties was investigated. Different digestion rates were obtained for gelatinized, retrograded starch by varying the enzyme dosage and reaction time. Analysis by high performance size-exclusion chromatography (HPSEC) coupled with multiangle laser-light scattering indicated that the molecular weighs of amylopectin and amylose were reduced during the digestion, to less than 100 kDa. A debranched chain length study using high performance anion-exchange chromatography equipped with an amyloglucosidase reactor and a pulsed amperometric detector and HPSEC revealed that short chains of amylopectin and noncrystalline amylose were rapidly digested, while DPn 121 chains showed resistance, followed by DPn 46 chains. X-ray diffraction analysis revealed that the crystalline structure in the treated starches survived cooking. These starches not only have slowly digestible and resistant character, but also retain some branched structure for adequate functionality.

High Glycemic Index Starch Promotes Hypersecretion of Insulin and Higher Body Fat in Rats without Affecting Insulin Sensitivity

In rats, prolonged feeding of high glycemic index (GI) starch results in basal hyperinsulinemia and an elevated insulin response to an intravenous glucose tolerance test (IVGTT). The aim of this study was to assess hepatic and peripheral insulin resistance (IR) using euglycemic hyperinsulinemic clamps. Insulin sensitivity, epididymal fat deposition and fasting leptin concentrations were compared in rats fed isocalorically a low or high GI diet for 7 wk (45% carbohydrate, 35% fat and 20% protein as energy) or a high fat diet (20% carbohydrate, 59% fat and 21% protein as energy) for 4 wk so that final body weights were similar. At the end of the study, high GI rats had higher basal leptin concentration and epididymal fat mass than the low GI group, despite comparable body weights. High GI and high fat feeding both resulted in the higher insulin response during IVGTT, but impaired glucose tolerance was seen only in rats fed high fat. The GI of the diet did not affect basal and clamp glucose uptake or hepatic glucose output, but high fat feeding induced both peripheral and hepatic IR. The findings suggest that hypersecretion of insulin without IR may be one mechanism for increased fat deposition in rats fed high GI diets.

Long term high glycemic index starch feeding leads to increased accumulation of visceral fat in adult rats

Long term high glycemic index starch feeding leads to increased accumulation of visceral fat in adult rats

A High Glycemic Index Starch Diet Affects Lipid Storage–Related Enzymes in Normal and to a Lesser Extent in Diabetic Rats

The of this study was to evaluate the chronic effects of a high (waxy corn) vs. a low (mung beans) glycemic index starch diet on the lipogenic enzymes, fatty acid synthase (FAS) and lipoprotein lipase (LPL). Normal and diabetic (streptozotocin-injected on d 2 of life) male Sprague-Dawley rats consumed a diet containing 575 g/kg carbohydrates either as waxy cornstarch (WCS) or as mung bean starch (MBS). After 3 wk, neither body weights nor relative epididymal fat pad weights differed. In diabetic rats, the WCS diet induced high basal plasma insulin levels. Plasma triglycerides were not significantly affected by diet in either normal or diabetic rats. Adipose tissue and liver LPL activities were not modified by the type of starch in the diet. In normal rats, FAS activity and gene expression in epididymal adipose tissue but not in liver were greater in rats consuming the WCS diet than in those consuming MBS. To evaluate the implication of insulin in this regulation, two genes regulated by insulin [GLUT4 and phosphoenolpyruvate carboxykinase (PEPCK)] were also studied. The high glycemic index WCS diet compared with the low glycemic index MBS diet resulted in lower hepatic PEPCK mRNA in both normal and diabetic rats. Normal, but not diabetic rats fed WCS had greater GLUT4 gene expression in adipocytes than did those fed MBS. We conclude that the total replacement of 575 g/kg low glycemic index starch by a high glycemic index starch for 3 wk caused the following in normal rats: 1) high FAS activity and mRNA in adipose tissue but not in liver and 2) high GLUT4 gene expression in adipose tissue. In both normal and diabetic rats this same diet resulted in lower hepatic PEPCK mRNA. Therefore, high glycemic index starch diet is implicated in stimulating FAS activity and lipogenesis and might have undesirable long-term metabolic effects.

Dietary Amylose-Amylopectin Starch Content Affects Glucose and Lipid Metabolism in Adipocytes of Normal and Diabetic Rats1,2

The aim of this study was to evaluate the effects of the chronic consumption of two starches, characterized by different glycemic indices and amylose-amylopectin content, on glucose metabolism in rat epididymal adipocytes. The two chosen starches were from mung bean (32% amylose) and cornstarch (0.5% amylose). The α-amylase digestibility was higher for the waxy cornstarch than that of the mung bean starch (60 ± 4 vs. 45 ± 3%, mean ± SEM, respectively). The glycemic index of the waxy cornstarch diet (575 g starch /kg diet) was higher than that of the mung bean starch diet (107 ± 7 vs. 67 ± 5%, P< 0.01) when measured in vivo in two groups of normal rats (n= 9). In a subsequent study, normal and diabetic (streptozotocin-injected on d 2 of life) male Sprague-Dawley rats (18 per group) consumed a diet containing 575 g starch/kg diet as either waxy cornstarch or mung bean starch. After 3 wk, food intake, epididymal fat pad weights, and plasma glucose, insulin and triglyceride concentrations did not differ between diet groups. Adipocyte diameter was smaller in rats that consumed mung bean starch compared with those that consumed the waxy cornstarch diet (P< 0.01). The mung bean diet increased maximal insulin-stimulated 14C-glucose oxidation (% of basal values, P< 0.05). In contrast, incorporation of 14C-glucose into total lipids was significantly lower in rats that consumed the mung bean diet (P< 0.05). We conclude that in both normal and diabetic rats, the chronic replacement of a high glycemic index starch by a low glycemic index one in a mixed diet increases insulin-stimulated glucose oxidation, decreases glucose incorporation into total lipids and decreases epididymal adipocyte diameter. Thus, the type of starch mixed into the diet has important metabolic consequences at the cellular level in both normal and diabetic rats.

Physiological and molecular mechanisms involved in nutritional regulation of fatty acid synthesis

Physiological and molecular mechanisms involved in nutritional regulation of fatty acid synthesis

Mechanisms and regulation of biosynthesis of saturated fatty acids.

Mechanisms and regulation of biosynthesis of saturated fatty acids.