Bread Reference Research Articles

Inconsistency between glycemic and insulinemic responses to regular and fermented milk products

Foods with a low glycemic index are increasingly being acknowledged as beneficial in relation to the insulin resistance syndrome. Certain organic acids can lower the glycemic index of bread products. However, the possible effect of acids in fermented milk products on the glycemic index and on insulinemic characteristics has not been addressed. The metabolic effects of fermented milk or pickled products used as additives to mixed meals have also not been addressed. One objective was to characterize the glycemic and insulinemic responses after intake of regular or fermented milk products (study 1). In addition, the acute metabolic effect of fermented milk (yogurt) and pickled cucumber as supplements to a traditional breakfast based on a high-glycemic index bread was evaluated (study 2). Ten healthy volunteers were served different breakfast meals after an overnight fast. Capillary blood samples were collected before and during 2 (study 1) or 3 (study 2) h after the meal. White-wheat bread was used as a reference meal in both studies. The lactic acid in the fermented milk products did not lower the glycemic and insulinemic indexes. Despite low glycemic indexes of 15-30, all of the milk products produced high insulinemic indexes of 90-98, which were not significantly different from the insulinemic index of the reference bread. Addition of fermented milk (yogurt) and pickled cucumber to a breakfast with a high-glycemic index bread significantly lowered postprandial glycemia and insulinemia compared with the reference meal. In contrast, addition of regular milk and fresh cucumber had no favorable effect on the metabolic responses. Milk products appear insulinotropic as judged from 3-fold to 6-fold higher insulinemic indexes than expected from the corresponding glycemic indexes. The presence of organic acids may counteract the insulinotropic effect of milk in mixed meals.

The Effects of Equal-energy Portions of Different Breads on Blood Glucose Levels, Feelings of Fullness and Subsequent Food Intake

Objective This study compared the effects of equal-energy portions of 7 different breads on feelings on fullness and subsequent ad libitum food intake. A satiety index score (SI) was calculated for each of the breads. Design Within-subject, repeated-measures design. Subjects and intervention Ten healthy subjects participated in the study. Subjects fasted for ⩾10 hours overnight and then reported to the research center the next morning, where they first completed baseline satiety ratings, gave a fasting blood sample, and then consumed a test bread. Additional finger prick blood samples and satiety ratings were collected at 15-minute intervals over 120 minutes, after which the subjects’ ad libitum intake of food was recorded. A satiety index (SI) score was calculated for each test food by dividing the area under the 120-m satiety response curve (AUC) for the test bread by the satiety AUC for the reference bread (regular white bread) and multiplying by 100%. Results The mean SI scores for the breads ranged from 100% to 561%, with regular white bread having the lowest SI score. Mean SI scores were negatively correlated with energy intake at a test meal after 120 m ( r=−0.88, P<.01, n=7) and total day energy intakes ( r=−0.72, P<.05, n=7). The strongest predictor of the breads’ SI scores was their portion size and thus energy density. The breads’ glycemic responses were not significantly associated with fullness responses. Applications Ingredients and food processing methods are available for the production of palatable, high-satiety versions of processed foods, which may be useful for weight control diets. SI scores would be a useful addition to food labels to indicate which foods are less likely to be overeaten and could be used by dietitians to develop weight control plans to help reduce energy intakes without increased hunger. J Am Diet Assoc. 2001;101:767–773.

Septoria nodorum blotch resistance in Aegilops tauschii and its expression in synthetic amphiploids

A collection of 433 Aegilops tauschii was screened for response to infection with Stagonospora nodorum. Resistance similar or marginally superior to the range observed in spring wheat genotypes was readily identified. Three lines, RL5271, Aus18911, and Aus21712, were resistant to a range of pathogen isolates and were similar in resistance to a highly resistant French line, No.33. Accessions of Ae. tauschii assessed as resistant or susceptible as seedlings had corresponding reactions when tested as adult plants, with resistance being commonly expressed as restricted lesion development. Infection frequency differed between some Ae. tauschii lines. Seedling resistance in synthetic bread wheats was expressed partially or not at all depending on both the tetraploid and the tetraploid/Ae. tauschii combination. Assessment of adult responses among a range of synthetics showed occasional expression of moderate resistance around the level observed among reference bread wheat cultivars of similar maturity. Disease escape associated with late maturity was common. One synthetic wheat, #231, derived from a resistant Ae. tauschii, exhibited low adult disease expression associated with late maturity. This line was resistant in seedling tests and seedling resistance was dominant in F1 hybrids to bread wheat.

An Examination of the Possibility of Lowering the Glycemic Index of Oat and Barley Flakes by Minimal Processing

Differences in glycemic responses to various starchy foods are related to differences in the rate of starch digestion and absorption. In this study, the importance of the degree of gelatinization and the product thickness for postprandial glycemic and insulinemic responses to rolled oats and barley were studied in healthy subjects (5 men and 5 women). Thick (1.0 mm) rolled oats were made from raw or preheated (roasted or steamed) kernels. In addition, thin (0.5 mm) rolled oats were made from roasted or roasted and steamed (processed under conditions simulating commercial production) oat kernels. Finally, steamed rolled barley kernels (0.5 or 1.0 mm) were prepared. All thin flakes elicited high glucose and insulin responses [glycemic index (GI), 88-118; insulinemic index (II), 84-102], not significantly different from white wheat bread (P: > 0.05). In contrast, all varieties of thick oat flakes gave significantly lower metabolic responses (GI, 70-78; II, 58-77) than the reference bread (P: < 0.05). Thick barley flakes, however, gave high glucose and insulin responses (GI, 94; II, 84), probably because the botanical structure underwent more destruction than the corresponding oat flakes. We conclude that minimal processing of oat and barley flakes had a relatively minor effect on GI features compared with the more extensive commercial processing. One exception was thick oat flakes, which in contrast to the corresponding barley flakes, had a low GI.

Low glycaemic-index foods.

Accumulating data indicate that a diet characterized by low glycaemic-index (GI) foods not only improves certain metabolic ramifications of insulin resistance, but also reduces insulin resistance per se. Epidemiological data also suggest a protective role against development of non-insulin-dependent diabetes mellitus and cardiovascular disease. A major disadvantage in this connection is the shortage of low-GI foods, and many common starchy staple foods, such as bread products, breakfast cereals and potato products, have a high GI. Studies in our laboratory show that it is possible to significantly lower the GI of starchy foods, for example by choice of raw material and/or by optimizing the processing conditions. Such low-GI foods may or may not influence glucose tolerance at a subsequent meal. Consequently, certain low-GI breakfasts capable of maintaining a net increment in blood glucose and insulin at the time of the next meal significantly reduced post-prandial glycaemia and insulinaemia following a standardized lunch meal, whereas others had no 'second-meal' impact. These results imply that certain low-GI foods may be more efficient in modulating metabolism in the long term. Although the literature supports a linear correlation between the GI and insulinaemic index (II) of foods, this is not always the case. Consequently, milk products elicited elevated IIs, indistinguishable from a white bread reference meal, despite GIs in the lower range. This inconsistent behaviour of milk products has not been acknowledged, and potential metabolic consequences remain to be elucidated.

Delayed gastric emptying rate may explain improved glycaemia in healthy subjects to a starchy meal with added vinegar.

The aim of the study was to evaluate the possible influence of acetic acid (administered as vinegar) on the postprandial glucose and insulin responses, and the potential involvement of a modified gastric emptying rate was studied by use of paracetamol as a marker. The white bread reference meal as well as the corresponding meal supplemented with vinegar had the same content of starch, protein and fat. The meals were served in the morning after an over-night fast and in random order. Capillary blood samples for analysis of glucose, insulin and paracetamol were collected postprandially. The study was performed at the Department of Applied Nutrition and Food Chemistry, Lund University, Sweden. Ten healthy volunteers, seven women and three men, aged 22-51 y, with normal body mass indices were recruited. The presence of acetic acid, given as vinegar, significantly reduced the postprandial glucose (GI=64) and insulin responses (II=65) to a starchy meal. As judged from lowered paracetamol levels after the test meal with vinegar, the mechanism is probably a delayed gastric emptying rate. Fermented foods or food products with added organic acids should preferably be included in the diet in order to reduce glycaemia and insulin demand.

Products Based on a High Fiber Barley Genotype, but Not on Common Barley or Oats, Lower Postprandial Glucose and Insulin Responses in Healthy Humans

Postprandial blood glucose and insulin responses to cereal products made from common barley, oats or a barley genotype containing elevated levels of β-glucans were evaluated in nine healthy subjects. Porridges were made from commercial Swedish wholemeal barley or oat flours, and a mixed whole-meal porridge using the high fiber barley genotype and commercial Swedish common barley (50:50). Also studied were two types of flour-based bread products composed of high fiber barley and common barley in ratios of 50:50 or 80:20, respectively. The common oat and barley porridges produced postprandial glucose and insulin responses similar to the white wheat bread reference, suggesting that the naturally occurring dietary fiber in these whole-meal flours has no impact on the glucose tolerance. In contrast, all high fiber barley products induced significantly lower responses than did the reference product, with the glycemic and insulin indices ranging from 57 to 72 or 42 to 72%, respectively. It is concluded that “lente” products of high sensory quality can be prepared from a barley genotype with an elevated content of soluble dietary fiber. The glycemic index of these products compares favorably with that of products made from common cereals, suggesting their use as a potential component of diets for patients with diabetes and hyperlipidemia, and for individuals predisposed to metabolic disease.

Response Surface Methodology in the Development of Rice Flour Yeast Breads: Sensory Evaluation

ABSTRACTYeast breads were developed from rice flour (80%) and potato starch (20%). Using sensory measurement from a trained panel, response surface methodology (RSM) was applied to find carboxymethylcel‐lulose (CMC), hydroxypropylmethylcellulose (HPMC), and water level combinations for gluten‐free breads from three different rice flours. Formulations resulted in rice breads that met wheat bread reference standards for moistness, cohesiveness, yeasty flavor, adhesiveness, aftertaste, top crust and crumb color, cell size uniformity and predominant cell size. Medium grain rice flour breads met more sensory reference standards than long grain rice flour breads.

Effects of lactic acid bacteria on the properties of sour dough bread

The effects of 13 different sour dough bacteria and a commercial sour dough starter from West Germany on the properties of sour dough bread were studied. As reference, a rye bread with lactic acid as souring additive was used. An expert taste panel, trained specifically for bread, was used to judge the bread. All organisms produced acids adequate for a good bread quality. However, the sour doughs fermented with the heterofermentative Lactobacillus spp. had higher acid equivalents, lower pH-values and also gave bread with stronger taste of acidity and acetic acid than those fermented with the homofermentative organisms. Correlation coefficients between taste values and analyses data also show that acetic acid has a great influence on the bread taste, whereas lactic acid seems to be of less importance. Two breads were judged to be somewhat different in taste compared to the others, namely those with sour doughs fermented with Lactobacillus alimentarius and Leuconostoc dextranicum. On comparison with the reference bread, the sour dough bread was judged to have a stronger taste of acidity and also a more aromatic and crispy crust. The bread baked with sour doughs fermented with the heterofermentative organisms, and thus containing the highest amounts of acetic acid, showed the best ability to prevent growth of the mould Eurotium rubrum.

Application of Response Surface Methodology to the Development of Rice Flour Yeast Breads: Objective Measurements

ABSTRACTA gluten‐free wheat bread replacement was developed from rice flour (80%) and potato starch (20%). Using objective measurements as responses, response surface methodology was utilized to find carboxymethylcellulose (CMC)‐hydroxypropylmethylcellulose (HPMC)‐water combinations which could successfully replace gluten in the rice flour yeast breads from each of three rice flours. CMC and water had the greatest effect on the responses measured; HPMC had the least. Rice bread formulations were found that resulted in breads which met wheat (white) bread reference standards for specific volume, crumb and crust color, Instron firmness and % moisture.