Helena Fredriksson

The influence of amylose and amylopectin characteristics on gelatinization and retrogradation properties of different starches

Physico-chemical properties of starch from wheat, rye, barley (waxy, high-amylose and normal-amylose), waxy maize, pea and potato (normal-amylose and high-amylopectin) were studied. Emphasis was given to the amylose (total, apparent and lipid-complexed) and amylopectin characteristics as well as to the gelatinization and retrogradation properties measured using differential scanning calorimetry. The total amylose content varied from ca. 1 % for waxy maize to 37% for high-amylose barley. The amylopectin characteristics were determined by high-performance size-exclusion chromatography after debranching with isoamylase. The weight-average degree of polymerization (DPw) was 26, 33 and 27 for the A-, B-, and C-type starches, respectively. In general, the potato starches exhibited the highest retrogradation enthalpies and the cereal starches the lowest, while the pea starch showed an intermediate retrogradation enthalpy. The data were analysed by principal component analysis (PCA). The DPw showed positive correlation to the melting interval, the peak minimum, the offset temperatures of the retrogradation-related endotherm as well as to the gelatinization and retrogradation enthalpies. However, the high-amylose barley retrograded to a greater extent than the other cereal starches, despite low DPw (24). The amylose content was negatively correlated to the onset and the peak minimum temperatures of gelatinization.

Studies on α-amylase degradation of retrograded starch gels from waxy maize and high-amylopectin potato

Abstract Gelatinized starch gels of waxy maize and high-amylopectin potato were subjected to different time–temperature conditions, aiming at producing extensive amounts of retrograded amylopectin. The purpose was to investigate the impact of amylopectin retrogradation on the resistant starch formation and on the rate of starch digestion with porcine pancreatic α-amylase. Dried non-cycled gelatinized starch gels were used for comparison. Although differential scanning calorimetry measurements indicated higher amounts of retrograded material in the dried temperature-cycled gels no enzyme resistant starch was detected in any of these samples. However, all cycled starch gels were less-readily degraded by the enzyme than the non-cycled gels. The chain length distribution in the α-amylolysates was studied by high performance anion exchange chromatography after debranching with isoamylase. The main products of hydrolysis were low molecular weight carbohydrates with a degree of polymerization of 1–9 and various branched dextrins. The chain distribution was uniform in the hydrolysates at the different stages of hydrolysis and independent of storage conditions, indicating that the mode of enzyme action remained unaffected by retrogradation. The waxy maize and high-amylopectin potato starches responded similarly to temperature cycling. It was concluded that temperature cycling resulted in a slower hydrolysis of the amylopectin, a phenomena that could be exploited when developing starchy foods with improved nutritional characteristics.

Rye kernel breakfast increases satiety in the afternoon - an effect of food structure

BackgroundThe structure of whole grain cereals is maintained to varying degrees during processing and preparation of foods. Food structure can influence metabolism, including perceived hunger and satiety. A diet that enhances satiety per calorie may help to prevent excessive calorie intake. The objective of this work was to compare subjective appetite ratings after consumption of intact and milled rye kernels.MethodsTwo studies were performed using a randomized, cross-over design. Ratings for appetite (hunger, satiety and desire to eat) were registered during an 8-h period after consumption of whole and milled rye kernels prepared as breads (study 1, n = 24) and porridges (study 2, n = 20). Sifted wheat bread was used as reference in both study parts and the products were eaten in iso-caloric portions with standardized additional breakfast foods. Breads and porridges were analyzed to determine whether structure (whole vs. milled kernels) effected dietary fibre content and composition after preparation of the products. Statistical evaluation of the appetite ratings after intake of the different breakfasts was done by paired t-tests for morning and afternoon ratings separately, with subjects as random effect and type of breakfast and time points as fixed effects.ResultsAll rye breakfasts resulted in higher satiety ratings in the morning and afternoon compared with the iso-caloric reference breakfast with sifted wheat bread. Rye bread with milled or whole kernels affected appetite equally, so no effect of structure was observed. In contrast, after consumption of the rye kernel breakfast, satiety was increased and hunger suppressed in the afternoon compared with the milled rye kernel porridge breakfast. This effect could be related to structural differences alone, because the products were equal in nutritional content including dietary fibre content and composition.ConclusionsThe study demonstrates that small changes in diet composition such as cereal grain structure have the potential to effect feelings of hunger and satiety.Trial registrationThis trial was registered at clinicaltrials.gov as NCT01042418.

Whole grain rye breakfast - sustained satiety during three weeks of regular consumption.

Whole grain rye products have previously been shown to increase feelings of satiety for up to 8h after intake under standardized conditions. This study was set out to investigate the sustainability of the satiating effect after regular consumption of breakfast meals with whole grain rye porridge or refined wheat bread. The study was randomized, cross-over and double-blind. Healthy subjects (n=24) were randomly assigned to daily consumption of iso-caloric standardized breakfast meals with whole grain rye porridge or refined wheat bread for two 3-wk phases, separated by a wash out of 3-4weeks. Each intervention phase had 3 scheduled visit days (days 1, 8 and 22) when appetite ratings (hunger, satiety and desire to eat) were registered for 24h at standardized conditions. Orocecal transit time (salicylazosulfapyridine/sulfapyridine method) and breath hydrogen as an indicator of colonic fermentation were measured at day 8 of each 3-wk phase in a subgroup (n=16). To investigate effects of breakfast on free-living food intake, 3-day weighed food diaries were self-registered during both intervention phases. Whole grain rye porridge breakfast resulted in higher ratings of satiety and lower hunger and desire to eat during 4h post consumption compared to refined wheat bread breakfast (p<0.001). This effect was sustained throughout the 3-wk study phases. Unlike previous studies, the effects did not persist into the afternoon (4-8h). The orocecal transit times after consumption of both breakfasts were similar and in the range of 5-6h. The rye porridge resulted in high levels of breath hydrogen 4-8h after intake, showing extensive colonic fermentation. This was however not related to any changes in appetite during this time-period. There were no significant differences in self-reported macronutrient- and energy intake between diets. This study shows that the satiating effect of rye persists after repeated daily consumption for up to three weeks. Clinicaltrials.gov Identifier: NCT01117363.

Effect of rye bread breakfasts on subjective hunger and satiety: a randomized controlled trial

BackgroundSeveral studies report that dietary fibre from different sources promotes the feeling of satiety and suppresses hunger. However, results for cereal fibre from rye are essentially lacking. The aim of the present study was to investigate subjective appetite during 8 h after intake of iso-caloric rye bread breakfasts varying in rye dietary fibre composition and content.MethodsThe study was divided into two parts. The first part (n = 16) compared the satiating effect of iso-caloric bread breakfasts including different milling fractions of rye (bran, intermediate fraction (B4) and sifted flour). The second part (n = 16) investigated the dose-response effect of rye bran and intermediate rye fraction, each providing 5 or 8 g of dietary fibre per iso-caloric bread breakfast. Both study parts used a wheat bread breakfast as reference and a randomised, within-subject comparison design. Appetite (hunger, satiety and desire to eat) was rated regularly from just before breakfast at 08:00 until 16:00. Amount, type and timing of food and drink intake were standardised during the study period.ResultsThe Milling fractions study showed that each of the rye breakfasts resulted in a suppressed appetite during the time period before lunch (08:30-12:00) compared with the wheat reference bread breakfast. At a comparison between the rye bread breakfasts the one with rye bran induced the strongest effect on satiety. In the afternoon the effect from all three rye bread breakfasts could still be seen as a decreased hunger and desire to eat compared to the wheat reference bread breakfast.In the Dose-response study both levels of rye bran and the lower level of intermediate rye fraction resulted in an increased satiety before lunch compared with the wheat reference bread breakfast. Neither the variation in composition between the milling fractions nor the different doses resulted in significant differences in any of the appetite ratings when compared with one another.ConclusionThe results show that rye bread can be used to decrease hunger feelings both before and after lunch when included in a breakfast meal. Rye bran induces a stronger effect on satiety than the other two rye fractions used when served in iso-caloric portions.Trial RegistrationTrial registration number NCT00876785

Effects of protein and starch characteristics on the baking properties of wheat cultivated by different strategies with organic fertilizers and urea

Protein and starch characteristics were analysed in white flour from one spring wheat (Kadett) and one winter wheat (Kosack) experiment grown with different levels of organic fertilizers or urea. Fertilization with meat bone meal and liquid manure, respectively, was used to represent organic farming and urea to represent conventional wheat production. The fertilizers were applied as three single doses of 30, 60 and 90 kg N ha−1 or split doses at two different growing stages, i.e. 30 + 30 kg N ha−1. No major differences between fertilizers were noticed. The main differences were found between experiments. Compared with the winter wheat, the spring wheat samples had a higher content of endosperm storage proteins, a lower content of detergent‐soluble proteins and a smaller diameter of large starch granules, and responded to increased N fertilizer applications by a significant increase in protein content and content of endosperm storage proteins. In the winter wheat samples, the starch content increased signi...

Whole grain rye porridge breakfast improves satiety compared to refined wheat bread breakfast.

Background Previous studies show that dietary fibre-rich foods with low energy density have a stronger effect on satiety per calorie compared to more energy dense foods. Objective To investigate subjective appetite and voluntary energy intake (24 h) after consumption of rye porridge breakfast and pasta lunch made from whole grain compared to iso-energetic reference meals made from refined cereals: wheat bread breakfast and wheat pasta lunch. Subjects In all, 22 healthy subjects, 14 females and 8 males, aged 21–64 years, BMI ranging from 18.7 to 27.5 kg/m2, participated. Design A randomised, crossover design was used. Appetite was rated by visual analogue scales (VAS) regularly from just before breakfast (08:00) until bedtime. An ad libitum dinner was served at 16:00. After leaving the clinic and in the morning day 2, subjects recorded foods consumed. Results Whole grain rye porridge gave a significantly prolonged satiety, lowered hunger and desire to eat (p<0.05 in most point estimates) up to 8 h after consumption compared to the refined wheat bread. The two pasta lunch meals did not vary in their effects on appetite ratings. There was no significant effect on ad libitum energy intake at 16:00 or self-reported energy and macronutrient intake in the evening and breakfast meal on day 2. Conclusions Whole grain rye porridge at breakfast has prolonged satiating properties up to 8 h after consumption compared to refined wheat bread, but did not diminish subsequent food intake.

WHEAT CULTIVATED WITH ORGANIC FERTILIZERS AND UREA : BAKING PERFORMANCE AND DOUGH PROPERTIES

Data describing white flour composition, dough properties and baking performance of both spring and winter wheat treated with different fertilizer strategies including meat bone meal, slurry manure and urea, were analyzed by principal component analysis and variance analysis. No significant differences in the analyzed variables were found between flour from wheat fertilized with organic fertilizers or urea at different N rates, irrespective of experiment. The differences mainly reflected variation between experiments. Higher N application rates significantly increased flour protein content and dough development time but decreased dough softening. Protein content was positively correlated to wet gluten content and dough stability, development time, resistance, extensibility as well as bread yield. The correlation between protein content and dough softening was negative and the correlation to farinograph water absorption was poor. The bread yield response to increasing protein content, obtained by increasin...

Calibration of a size-exclusion chromatography system using fractions with defined amylopectin unit chains

A high-performance size-exclusion chromatography (HPSEC) system was successfully calibrated using fractions of debranched amylopectin unit chains, obtained by gel filtration, and with the average chain length of the fractions determined by high-performance anion-exchange chromatography. As a comparison, calibration of the HPSEC system was also performed using maltoheptaose and pullulan standards as reference substances. The relationships between the degree of polymerization and the retention time for the defined amylopectin unit chain fractions and the commercial standards, i.e. maltoheptaose and pullulans, were very similar, indicating similar elution behaviour.

Effect of Different Extrusion Parameters on Dietary Fiber in Wheat Bran and Rye Bran

Wheat bran and rye bran are mostly used as animal feed today, but their high content of dietary fiber and bioactive components are beneficial to human health. Increased use of bran as food raw material could therefore be desirable. However, bran mainly contains unextractable dietary fiber and deteriorates the sensory properties of products. Processing by extrusion could increase the extractability of dietary fiber and increase the sensory qualities of bran products. Wheat bran and rye bran were therefore extruded at different levels of moisture content, screw speed and temperature, in order to find the optimal setting for increased extractability of dietary fiber and positive sensory properties. A water content of 24% for wheat bran and 30% for rye bran, a screw speed of 400 rpm, and a temperature of 130 °C resulted in the highest extractability of total dietary fiber and arabinoxylan. Arabinoxylan extractability increased from 5.8% in wheat bran to 9.0% in extruded wheat bran at those settings, and from 14.6% to 19.2% for rye bran. Total contents of dietary fiber and arabinoxylan were not affected by extrusion. Content of β-glucan was also maintained during extrusion, while its molecular weight decreased slightly and extractability increased slightly. Extrusion at these settings is therefore a suitable process for increasing the use of wheat bran and rye bran as a food raw material.