Effect of guar gum on the serum lipid profile of Sprague Dawley rats

The aim of the study was to probe the hypocholesterolemic effect of legumes dietary fiber through “chapaties” a staple diet of the South Asia. Commercial wheat flour (atta) was blended with legumes i.e. lentil, chickpea and guar gum in various combinations to make composite flour for the preparation of chapaties. Maximum dietary fiber (8.85%) was observed in composite flour with 3g/100 g guar gum, which also gave whiter look and puffiness to the end product. Highest percent increase in dietary fiber (35.3%) was in flour with 3g/100 g guar gum followed by guar gum 2g/100 g (24.1%). The diets prepared from three best selected compositions along with control, were fed to male Sprague Dawley rats for 8 weeks. Lowest serum cholesterol (82.46 mg/dl) was observed in rats fed on guar gum 3g/100 g which showed a significant reduction (17.2%) as compared to control. Similarly, in case of LDL and triglycerides, guar gum 3 g/100 g showed highest decline i.e., 29.7% and 28.4% with reference to control, respectively. The present investigation suggests that five chapaties per day prepared from selected compositions provides an extra 5-8 g of dietary fiber that is helpful in lowering cholesterol in hypercholesterolemic individuals.     

不同品种膳食纤维影响小鼠糖耐量结果的比较

本文选择多功能大豆纤维（MSF）、小麦纤维、纤维素、果胶和瓜儿胶等5种膳食纤维，对其影响小鼠葡萄糖耐量结果作了比较与分析。结果显示，1.0g/kg MSF、果胶或瓜儿胶可使葡萄糖耐量曲线变得尤为平缓，而同剂量纤维素和小麦纤维的效果并不显著。水溶性、粘性膳食纤维具有明显的稳定餐后血糖的作用，原因可能在于它能增加小肠内容物粘性，增加肠内非搅动层（unstirred layer）的厚度，并能使胃的排空速率降低，从而显著降低葡萄糖吸收速度。     

EFFECT OF DIETARY FIBER ON THE PREVENTION OF LIVER LIPID ACCUMULATION INDUCED BY HIGH POLYUNSATURATED OIL

This study investigated whether dietary fiber can prevent the accumulation of liver lipids due to the ingestion of polyunsaturated oil. Fifteen percent fish oil (FO) was added to the basal diet as a source of polyunsaturated oil. Ten percent cellulose, pectin, guar gum, konjac mannan or gum Arabic was mixed in the diet as a source of dietary fiber. Commercial Purina rat chow was used as a control and a fiber-free (blank) diets were also employed in the study. Each experimental diet was fed to each group of 6 Wistar rats for 8 weeks. Fish oil feeding lowered the plasma triacylglycerols (TG) and cholesterol (CS) levels. Rats fed a fiber-free diet had higher liver weights indicating hepatomegaly and a marked accumulation of liver lipids. With the exception of cellulose and gum Arabic, the inclusion of dietary fiber in FO diets lowered the plasma total lipids and CS; plasma TG was unchanged. Pectin and guar gum enhanced the CS-lowering effect of the FO diet. All of the test fibers, but especially pectin and guar gum, reduced the accumulation of total lipids, TG and CS in rat liver caused by dietary FO. Hepatic glucose-6-phosphate dehydrogenase activity was reduced in rats fed FO, but dietary fiber had no effect on the activity of this enzyme.     

苦荞中可溶性及不可溶性膳食纤维调控糖尿病小鼠糖脂代谢的功效

本研究采用苦荞麸皮粉中提取的膳食纤维对高脂/链脲佐菌素诱导的糖尿病小鼠进行干预,比较苦荞麸皮粉中的可溶性膳食纤维（soluble dietary fiber,SDF）和不可溶性膳食纤维（insoluble dietary fiber,IDF）的含量及作用差异,解析苦荞中SDF及IDF对调控糖尿病小鼠血糖及血脂代谢作用的贡献。结果：苦荞麸皮中IDF的质量分数（（19.52±0.21）%）约为SDF（（4.02±0.19）%）的5 倍;相同干预剂量下SDF比IDF能更有效地发挥降血糖作用,但当IDF干预剂量达到SDF的5 倍时,IDF降低血清中的总胆固醇和低密度脂蛋白胆固醇水平的效果更显著（P＜0.05）,并且能够和SDF一样有效促进胰岛素分泌并改善糖耐量、降低肝脏中总胆固醇水平、促进短链脂肪酸的产生。结论：苦荞SDF和IDF均具有改善糖耐量、降低血清及肝脏中脂肪积累的功效,且都与盲肠中短链脂肪酸含量的增加密切相关;研究揭示了苦荞SDF及IDF在量效关系上的差异,为充分理解谷物中不同膳食纤维的糖脂调控功效提供了科学证据。     

复合膳食纤维素的结构及物性研究

采用大豆纤维素为基料,水溶性天然植物胶——瓜尔豆胶、果胶为辅料复合后,制备一种兼有水溶性和非水溶性双重特性的复合膳食纤维素。测定复合膳食纤雏素的粘度和表面张力,并对复合膳食纤维素体系进行扫描电镜观察后发现,大豆纤维素与瓜尔豆胶复合物的粘度和表面张力较两种单一成分均有明显提高,且复合物可调和成为以瓜尔豆胶溶胶为基体、大豆纤维素颗粒均匀镶嵌其间的稳定体系。大豆纤维素与果胶复合物的上述指标也有提高,但体系不稳定。     

Comparative Effects of Particle Size Reduction on Physical Structure and Water Binding Properties of Several Plant Fibers

Reducing the particle size of AACC wheat bran decreased water-holding capacity, due, in part, to the collapse of its fiber matrix. Physical structure of commercial oat bran collapsed during manufacture and further grinding had limited effect. Physical structure of microcrystalline celluloses and guar gums did not differ between product types. The amount of water held by oat bran and microcrystalline cellulose was increased by reducing particle size. Water binding properties of guar gum were not affected. Physical structure of dietary fiber must be considered if water-binding properties are to be useful predictors of stool bulking efficiency.     

不同剂量苹果膳食纤维对小鼠高血糖和高血脂的影响

为研究不同剂量苹果膳食纤维对糖尿病小鼠血糖水平和高脂饮食小鼠血脂水平的影响,以ICR小鼠为实验动物,分别给糖尿病模型和高脂饮食小鼠饲料中添加4%、2%、1%剂量苹果膳食纤维,另设对照组;喂养结束后分别测定其空腹血糖和血脂水平。结果显示：1%～4%剂量苹果膳食纤维不能降低糖尿病小鼠血糖值,但4%剂量可以抑制其血糖值显著升高。4%剂量苹果膳食纤维可有效降低高脂饮食小鼠血清胆固醇(TC)含量和动脉硬化指数(AI),但不能恢复至正常水平;对血清甘油三酯(TG)含量可有效降低至接近正常水平;而较低剂量未发现有效作用。结论：苹果膳食纤维对小鼠的辅助降血糖和降血脂作用,当饲料中添加剂量达到4%时,才会有显著效果,较低剂量作用不显著。     

In Vitro Fermentabilities of Purified Fiber Supplements

Six commonly used dietary fiber supplements (pectin, tragacanth gum, psyllium gum, guar gum, soy fiber and cellulose) were fermented in vitro with human fecal microbiota for 4, 8,12, and 24 hr. Short chain fatty acids (SCFA), hydrogen and methane productions, and neutral-detergent fiber digestibility differed significantly with fiber source. The most rapid fermentation rate was with pectin followed by psyllium gum, tragacanth gum, guar gum, soy fiber, and finally cellulose. Such differences in fermentability should be considered when food products are formulated. Dietary fiber source and intake may also affect breath hydrogen measurements and estimates of available carbohydrate malabsorption.     

部分水解瓜尔豆胶对高脂高糖饮食诱导小鼠代谢紊乱的调节作用

部分水解瓜尔豆胶(partially hydrolyzed guar gum,PHGG)是一种有益于代谢平衡的可溶性膳食纤维,但其对糖脂代谢紊乱的调节效果及其潜在机制尚不明确.利用高脂高糖饮食诱导小鼠16周,使其产生明显的脂代谢紊乱和胰岛素抵抗,进一步通过检测小鼠糖耐量、血清生化指标、脂肪形态、肠道短链脂肪酸及相关mRNA的表达,考察PHGG对模型小鼠的糖脂代谢稳态及肠道环境的调节作用.结果表明:长期高脂高糖饮食条件下,PHGG组小鼠比模型组小鼠的体质量增长率减缓,空腹血糖降低,葡萄糖耐量和胰岛素耐量显著提升;血清中的甘油三酯、总胆固醇、低密度脂蛋白胆固醇和游离脂肪酸可分别降低21.56％、32.67％、25.66％和22.91％,明显抑制了脂肪积累.PHGG将肠道胰高血糖素样肽-1的分泌提升并恢复到67.76 pmol/L,盲肠中的丁酸含量比模型组提升了7.14倍.定量PCR显示,PHGG干预后小鼠短链脂肪酸受体GPR43的蛋白表达水平比模型组提升了63.30％.本研究表明,PHGG通过调节短链脂肪酸影响脂联素、胰岛素的分泌,进而改善高脂高糖饮食引起的糖脂代谢紊乱,可以应用于辅助糖脂代谢调控的功能性食品开发中.     

Onion (<Emphasis Type="Italic">Allium cepa</Emphasis> L.) by-products as source of dietary fiber: physicochemical properties and effect on serum lipid levels in high-fat fed rats

The effect of industrial processes used to obtain onion by-products was evaluated. Fiber composition and physicochemical properties were assessed in order to choose the best process to obtain high-fiber ingredients. Moreover, the effect of the inclusion of the dietary fiber-rich onion by-products in a high-fat diet on serum lipids of rats was also evaluated. Bagasse was the best by-product since it showed the highest fiber content with a balanced soluble-to-insoluble fiber ratio and the best physicochemical properties. This fact is related to its high fiber content and also due to its composition, rich in uronic acids and polysaccharides, which explains its high cation exchange capacity, water-holding capacity and swelling capacity. In addition, the inclusion of Bagasse in a high-fat diet produced a reduction in the serum lipid and total cholesterol increases induced by high-fat diet. This effect could be related to the high cation exchange and swelling capacities that Bagasse showed, since these properties can create a concerted effect in reducing the number of intact micelles available, the transit time, and consequently the total time available for cholesterol and lipid absorption in the small intestine.     

Sensory Optimization of Broken-Rice Based Snacks Fortified with Protein and Fiber

ABSTRACT:  A 3-component mixture experiment was used to optimize the formulation of broken-rice based snack fortified with protein and fiber based on consumer sensory acceptability. Soy protein isolate and guar gum were used as a good source of protein and fiber, respectively, according to DRV (daily reference value) based on a 2000-calorie diet. A consumer panel evaluated sensory acceptability of color, crispness, and flavor, and overall liking of 12 experimental broken-rice based snack formulations. Predicted models derived from the restricted nonintercept regression analysis were used to plot mixture response surfaces (MRS) of each sensory attribute. Areas within the MRS plots having predicted acceptability scores of at least 6.5 (on a 9-point hedonic scale) for color, crispness, flavor, and overall liking were selected to derive a predicted optimum formulation range. Flavor acceptability was a limiting factor in attaining the optimum formulation range, which consisted of 40% to 48% broken-rice flour, 8% to 16% guar gum, and 20% to 33% soy protein isolate. To verify the obtained predicted models, the formulation containing 48% broken-rice flour, 8% guar gum, and 20% soy protein isolate, which was located in the optimum area, was chosen to support our effort to utilize and add value to broken rice. Selected physicochemical measurements of the chosen optimized formulation were determined. One serving size (30 g) of the chosen optimized snack product provided 6.58 g protein and 3.80 g dietary fiber, which met the US FDA definition of a good source of protein and dietary fiber.     

Development and characterization of soluble fiber enriched noodles via fortification with partially hydrolyzed guar gum

Partially hydrolyzed guar gum was prepared via enzymatic hydrolysis of native guar gum. Partially hydrolyzed guar gum (PHGG) thus obtained after enzymatic hydrolysis contained 80.04% soluble dietary fiber and 83.1% total dietary fiber. In present study, the effect of process variables such as PHGG level (1–5%), water level (30–40%) and mixing time (2–6 min) on response variables i.e. cooking yield, cooking loss and overall acceptability of noodles were studied using response surface methodology. The second order model obtained for cooking yield, cooking loss and overall acceptability of noodles revealed coefficient of determination of 0.9796, 0.9446 and 0.7787, respectively. The optimum values for independent variables i.e. PHGG level, water level and mixing time were 2.23, 32.03% and 2.81 min, respectively. Results showed that noodles with reduced cooking yield, increased cooking loss and improved sensory and textural characteristics were prepared with fortification of 2.23% partially hydrolyzed guar gum as soluble fibre.     

Molecular weight of guar gum affects short-chain fatty acid profile in model intestinal fermentation

Dietary fiber exerts many beneficial physiological effects; however, not all types of dietary fiber display the same effects. Partially hydrolyzed guar gum (PHGG), a lower molecular weight form of guar gum, is more easily incorporated into food, but may have less pronounced physiological effects than the native form. The aim of this study was to identify differences in intestinal fermentability based on the molecular weight of guar gum. Guar gum of four molecular masses (15, 20, 400, and 1,100 kDa) was fermented using a batch in vitro fermentation system. Human fecal inoculum was the source of microbes. The 400-kDa fraction produced the greatest concentrations of total short-chain fatty acid (SCFA) at 8 h and the highest amounts of butyrate at 24 h. At 24 h, the 400-kDa fraction produced more total SCFA and propionate than the 15 kDa, but was not different than 20 kDa or 1,100 kDa fractions. The molecular weight of guar gum was positively correlated with acetate production and negatively correlated with propionate production. This study concludes that 400-kDa guar gum may be optimal for intestinal fermentability. In conclusion, the molecular weight of guar gum affects in vitro fermentability and should be considered when adding to a food or beverage.     

DEGRADATION OF GUAR GUM BY ENZYMES PRODUCED BY A BACTERIUM FROM THE HUMAN COLON

A strain of Bacteroides ovatus from the human colon was grown on guar gum, a highly-branched galactomannan which is widely used as a food additive. Growth on guar gum induced production o f extracellular enzymes which partially degraded and/or deaggregated guar gum. The enzymes rapidly reduced the viscosity of guar gum solutions, while breaking only a limited number of glycosidic bonds. The molecular weight (versus dextran standards) of the guar gum decreased sharply as the viscosity decreased. No mono-, di- or trisaccharides were produced during enzyme action, although small quantities of higher oligomers were present after longer (5–8 h) incubations. The enzyme had a sharp temperature optimum at 37°C for an incubation time of 60 min, but was stable for only a few hours at this temperature. These results demonstrate how enzymes produced and elaborated by human colon bacteria can markedly alter the physical properties of a dietary component which reaches the colon. Further studies of both substrate and enzymes will be required to establish the mechanism of this alteration and to establish how B. ovatus is able to utilize guar gum for growth.     

The viscosity of dilute solutions of guar gum and locust bean gum with and without added sugars

The apparent viscosities of dilute solutions of guar and locust bean gums have been measured. The intrinsic viscosity [n] of guar gum solution is greater than that of locust bean gum solution, but the interaction coefficient k of guar gum solutions is less than that of locust bean gum. Addition of glucose, sucrose, or glucose syrup increases the apparent viscosity of the gum solution. The intrinsic viscosity of the gum solution is decreased but the interaction coefficient is increased.     

Effect of beta-glucan from oats and yeast on serum lipids

Heart disease is the leading cause of death in the U.S. One way to reduce the risk of developing the disease is to lower serum cholesterol levels by making dietary changes. In addition to reducing intake of total fat, saturated fat, and dietary cholesterol, serum cholesterol can be further reduced by added fiber, especially from sources rich in beta-glucan. In this review, two sources of beta-glucan are described; one source is oats and the other yeast. Their chemical structures and physical properties are compared, and their effect on serum lipid levels is described. Oat beta-glucans are found in various breakfast cereals and snacks. Usually, several servings of these products are required to meet the Food and Drug Administration's claim of reducing the risk of heart disease. The yeast-derived fiber is a more concentrated source of beta-glucan than the oat product. It is currently being tested in a wide variety of food products.     

TOTAL AND SOLUBLE DIETARY FIBER VARIATION IN CYAMOPSIS TETRAGONOLOBA (L.) TAUB. (GUAR) GENOTYPES

The endosperm of guar seed is the source of a soluble hydrophilic polysaccharide gum that is used as an emulsifier, thickener and stabilizer in a wide range of foods and is part of the seed total dietary fiber (TDF). This study examined the content and variation in TDF and soluble dietary fiber (SDF) in seeds of guar, Cyamopsis tetragonoloba (L.) Taub., accessions with diverse morphological traits. TDF and SDF, respectively, made up 52–58% (n = 9 accessions) and 26–32% (n = 8 accessions) of seed dry weight. Both TDF and SDF displayed significant genotypic variability. The magnitude of the variability indicates the possibility of improving these traits through plant breeding. Variability of protein, lipid, ash and dry matter content of seed was also observed.     

Canonical correlation: a multivariate technique to determine the contribution of various dependent and independent variables

Composite flour chapaties were prepared by blending wheat, guar gum, lentil and chickpea flours in different proportions to evaluate their hypoglycaemic and hypocholesterolaemic worth because of their fibre content. Stepwise regression analysis revealed that dietary fibre and intestine length contributed negatively, while peroxide value (POV) contributed positively to the serum cholesterol and glucose. Likewise, for total chapati scores, dough stability and phytic acid showed inverse contribution, while folding ability, dough development time, dietary fibre, POV, crude fibre and texture performed positively. The canonical correlation was applied to develop a model between two groups of variables, where the first group comprised three dependent variables, i.e. total chapati scores, cholesterol and glucose and the second set comprised thirteen independent variables, i.e. crude fibre, POV, phytic acid, dietary fibre, dough development time, dough stability, feed intake, intestine length, low‐density lipoprotein, triglycerides, albumin, texture and folding ability. The selection of independent variables was based on the significant chemical, rheological, sensory and efficacy characteristics in a multiple stepwise regression. The value of coefficient of determination for dietary fibre of the flour samples was observed to be 0.99749 indicating that 99.74% of the variation in dietary fibre can be explained by all other variables in the second set. However, 17.35% and 4.83% of variation in total chapati scores and cholesterol levels, respectively, can be explained by the entire variables in the first group, while 17.20% of variation in glucose can be explained by all other variables of the first group. The squared multiple regression of each variable in the first set with all the variables in the second set indicated that a 99.97% variation in total chapati scores, cholesterol and glucose is explained by the variables in the second set. The F‐values were significant for total chapati scores, cholesterol and glucose. The results substantiated that all the variables in the second set are important to account for the significant variation for the variables tested in the first set. Canonical analysis revealed the existence of a high correlation between dependent variables and other independent variables.     

Dietary fibre, glycaemic response, and diabetes

The much publicised global trend in rising levels of obesity and diabetes has refuelled interest in the dietary intake of the macronutrients (fat, protein, and carbohydrates) necessary to maintain the state of normalcy (good health) of an individual. Both scientific and public attention have focused on the dietary mediation of chronic health syndromes, either through use of dietary supplements, or a review of the whole diet situation. Dietary supplements have been used extensively both as pharmacological supplements, food ingredients, in processed foods to aid weight control, and the regulation of glucose control for diabetic patients. Particular interest has focused on the use of dietary fibres, especially soluble dietary fibres (such as guar gum, locust bean gum, and psyllium fibres), resistant starch, and slowly digestible carbohydrates. These have been shown to alter food structure, texture, and viscosity, and hence the rate of starch degradation during digestion. Research has also illustrated an association between the rate of carbohydrate degradation during digestion, and the regulation of postprandial blood sugar and insulin levels. The current paper explores the potential use of dietary fibres in the treatment of obesity and diabetes.     

Butyric acid modulates activities of intestinal and renal disaccharidases in experimentally induced diabetic rats

To elucidate the effect of feeding of butyric acid on disaccharidase activities, the specific activities of the disaccharidases were measured in the intestinal mucosa and kidney cortex of control and diabetic rats. Diabetes was induced in rats using streptozotocin. Rats were fed with basal diet containing wheat bran (5%) as a source of insoluble dietary fiber and guar gum (2.5%) as a source of soluble dietary fiber. The experimental group received butyric acid at 250, 500 and 750 mg/kg body weight/day. Increased activities of intestinal maltase, sucrase and lactase in diabetic rats were significantly reduced in fiber-fed diabetic group. Supplementation of butyric acid at 500 mg/kg body weight/day showed a further decrease in their activities. The activity of disaccharidases in renal tissue was decreased in diabetic rats and was significantly improved in fiber-fed diabetic group. Butyric acid feeding at 500 mg/kg body weight/day showed further improvement in their activities.