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 ß-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.

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.

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

BACKGROUND: The 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. METHODS: Two 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. RESULTS: All 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. CONCLUSIONS: The study demonstrates that small changes in diet composition such as cereal grain structure have the potential to effect feelings of hunger and satiety. TRIAL REGISTRATION: This trial was registered at clinicaltrials.gov as NCT01042418.

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

BACKGROUND: Several 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. METHODS: The 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. RESULTS: The Milling fractions study showed that each of the rye breakfasts resulted in a suppressed appetite during the time period before lunch (08:3012:00) 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. CONCLUSION: The 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 REGISTRATION: Trial registration number NCT00876785.

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/m(2), 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.