The relative absorption of fatty acids in brown trout (Salmo trutta) fed a commercial extruded pellet coated with different lipid sources

The objective of the present study was to investigate the fatty acid absorption capabilities of brown trout (Salmo trutta) fed commercial extruded diets. Five commercial extruded pellets, different only in the lipid sources used for fat coating, were tested on juvenile brown trout for 45 days. The trout were reared in fresh water at 14.6 ± 0.4° C and 7.7 ±
0.3 mg/l, temperature and dissolved oxygen, respectively. The tested lipid sources were fish oil, canola oil, oleine oil, swine fat and poultry fat. After the adaptation period faeces were collected by gently stripping from naesthetized fish. Fatty acid analysis was performed on experimental diets and on collected faeces to evaluate the relative absorption capabilities of the trout digestive system with respect to each detected fatty acid. The use of the relative absorption efficiency (rAE) was opted to evaluate the intrinsic capability of each fatty acid to be absorbed. Brown trout showed a
specific preferential order of absorption of the fatty acids, preferring shorter over longer chain fatty acids and preferring the more unsaturated to the more saturated fatty acids. The fatty acid that showed the best relative absorbability was the C18:4n-3 (rAE = 5.14 ± 0.72), which has a fairly short carbon chain, but at the same time a high unsaturation level, followed by the C18:3n-3 (rAE = 3.38 ± 0.30). The fatty acid that showed the worst relative absorbability (rAE = 0.21 ± 0.02) was C24:1n-9.

Palatability and glucose, insulin and satiety responses of chickpea flour and extruded chickpea flour bread eaten as part of a breakfast

Objective: To determine the effect of adding chickpea flour or extruded chickpea flour to white bread on palatability and postprandial glycaemia, insulinaemia and satiety.

Design: A randomised, single-blind, cross-over study of four 50 g available carbohydrate breakfasts.

Setting: School of Exercise and Nutrition Sciences, Deakin University.

Subjects: In all, 12 healthy subjects were recruited through posted notices. Totally, 11 (nine male, two female) completed the study (meanplusminuss.e.m.; age 32±2 y; body mass index, 24.7±0.8 kg/m²).

Intervention: After overnight fasting, subjects consumed a control (white) bread (WB) breakfast twice, a chickpea bread (CHB) breakfast once and an extruded chickpea bread (EXB) breakfast once. Palatability and postprandial blood glucose, insulin and satiety responses were determined. Following this, food intakes from an ad libitum buffet and for the remainder of the day were assessed.

Results: A trend towards a lower incremental area under the curve (IAUC) of glucose for the CHB breakfast compared to the WB breakfast was observed (P=0.087). The IAUC of insulin and insulinaemic index (II) of the CHB breakfast were higher (P<0.05) than for the WB breakfast. No differences in glycaemic index (GI), satiety response, food intake or palatability were observed.

Conclusions: CHB and EXB demonstrated acceptable palatability. CHB demonstrated some hypoglycaemic effect compared to WB, but neither CHB nor EXB demonstrated effects on satiety or food intake. The hyperinsulinaemic effect of CHB observed in this study requires further investigation.

Impact of ripening stages of banana flour on the quality of extruded products

The study investigated the physical, nutritional and sensory properties of different ripening stages of banana during extrusion processing in combination with rice flour to develop quality snack products. Dehydrated banana flours at ripening stages 4, 5 and 6 (peel colour) were mixed separately at 40% banana to 60% rice flour levels. The mixtures were extruded through a twin-screw extruder at 120 °C barrel temperature, 220 and 260 r.p.m, screw speed and 12% feed moisture. Increase in ripeness indicated negative effect on expansion and water absorption capacity while increasing the water solubility index and moisture retention (wet basis) of the products. Protein and mineral (except for zinc and copper) content of the products were significantly different (P < 0.05) from 4 to 6 of the ripening stages. Most of the essential amino acids in the extruded products increased significantly (P < 0.05) at the ripening stage of 6. All the products were within the acceptable range in the 9-point Hedonic scale showing the best texture and flavour scores for stage 4 and 6, respectively. The extruded products show potential as snack products because of their nutritional quality and sensory acceptability.

Functional extruded snack products based on chickpea (Cicer arietinum L.) and fenugreek (Trigonella foenum-graecum) flours

Background – Chickpea and fenugreek are both legumes that confer several nutritional and functional virtues, especially to diabetes and associated metabolic syndrome conditions. They are high in protein and fibre, low in fat and prove to be low glycaemic. They also provide a gluten-free alternative to those suffering from celiac disease. Though these seeds are locally available, hardly any products appear on the supermarket shelves.
Objectives – The aim was to utilise the health and nutritional benefits of chickpea and fenugreek and develop acceptable snack products by extrusion technology.
Design – Preliminary trials were conducted with different proportions of rice and chickpea at a range of extruder conditions to optimise the raw material and processing conditions. Studies were then conducted at optimum processing conditions using a 7:3 chickpea and rice combination replacing with 2% fenugreek or 5, 10, 15 and 20% FenuLifeÒ (deodorized fenugreek powder). Products were evaluated for their physical (expansion, crunchiness and colour) and sensory ( texture, colour, flavour and overall acceptability) characteristics in order to identify their suitability as snack products.
Outcomes – Addition of chickpea up to 70% with rice showed increased expansion and stable product characteristics. Addition of fenugreek and FenuLifeÒ, indicated slight reduction in product expansion (radial) and crunchiness. However, the product made with 20% FenuLifeÒ had significant changes in expansion, crunchiness and colour values. The median scores of sensory evaluation indicated that all products were within the acceptable range. Inclusion of fenugreek showed lower ratings for flavour due to the strong bitter taste of fenugreek. There were no significant differences between products containing FenuLifeÒ (5-15%) in their colour, flavour, texture and overall quality.
Conclusion – This study demonstrates an opportunity for using chickpea and fenugreek in functional product development. Fenugreek in the form of deodorize powder (fenulifeÒ) could be incorporated up to 15% in a mixture of chickpea and rice to develop snack products of acceptable physical and sensory properties.

The origin of "Rare Earth" texture development in extruded Mg-based alloys and its effect on tensile ductility

The extrusion behaviour, texture and tensile ductility of five binary Mg-based alloys have been examined and compared to pure Mg. The five alloying additions examined were Al, Sn, Ca, La and Gd. When these alloys are compared at equivalent grain size, the La- and Gd-containing alloys show the best ductilities. This has been attributed to a weaker extrusion texture. These two alloying additions, La and Gd, were found to also produce a new texture peak with View the MathML source parallel to the extrusion direction. This “rare earth texture” component was found to be suppressed at high extrusion temperatures. It is proposed that the View the MathML source texture component arises from oriented nucleation at shear bands.

Effect of microalloying with rare-earth elements on the texture of extruded magnesium-based alloys

A series of alloys have been produced with microalloying additions of rare-earth (RE) elements in the range of 0.1–0.4 wt.%. The alloys have been extruded to produce grain sizes of 23 ± 5 μm. The texture of the extruded alloys was measured, and it was found that the extrusion texture was weakened by the addition of RE elements. The samples with weakened extrusion textures exhibited an increase in the tensile elongation.

Extruded products with Fenugreek (Trigonella foenum-graecium) chickpea and rice: Physical properties, sensory acceptability and glycaemic index

The present study investigated the effects of fenugreek flour (Trigonella foenum-graecum) and debittered fenugreek polysaccharide (FenuLife^®) inclusion on the physical and sensory quality characteristics, and glycaemic index (GI) of chickpea–rice based extruded products. Based on preliminary evaluation with different proportions of chick pea and rice, a blend of 70:30 chickpea and rice was chosen as the control for further studies. The control blend, replaced with fenugreek flour at 2%, 5% and 10%, or fenugreek polysaccharide at 5%, 10%, 15% and 20%, was extruded at the optimum processing conditions as specified in the detailed study. The extruded products were evaluated for their physical (moisture retention, expansion, hardness, water solubility index (WSI) and water absorption index (WAI)), sensory (flavor, texture, color and overall acceptability) characteristics and in vitro GI to evaluate their suitability as extruded snack products.

Due to the distinct bitter taste, inclusion of fenugreek flour was not acceptable at levels more than 2% in extruded chickpea based products. Addition of fenugreek polysaccharide resulted in slight reduction in radial expansion (P < 0.05), while longitudinal expansion increased. WAI increased while WSI decreased compared to the control (P < 0.05). The mean scores of sensory evaluation indicated that all products containing fenugreek polysaccharide up to 15% were within the acceptable range. There were no significant differences (P > 0.05) between products containing 5–15% fenugreek polysaccharide in their color, flavor, texture and overall quality.

Fenugreek, in the form of debittered polysaccharide (FenuLife^®) could be incorporated up to a level of 15% in a chickpea–rice blend to develop snack products of acceptable physical and sensory properties with low GI Index.

Texture and mechanical anisotropy in three extruded magnesium alloys

One ZM61 alloy (6·2%Zn, 1·2%Mn) and two magnesium alloys containing nominally 3% of neodymium and yttrium respectively have been prepared in the form of hot extruded flat strips. Their textures and microstructures have been quantified and series of mechanical tests were carried out to determine plane stress yield loci in both the solution treated and aged conditions. The ZM61 alloy had a sharp texture and marked anisotropy of strength that could be rationalised in terms of deformation by basal <a> slip and {1012}<1011> twinning. This material was much weaker in compression than in tension. Precipitation hardening on aging caused a greater impedance to twinning than to slip with the result that the anisotropy was somewhat reduced. The Mg–3Nd alloy had a very weak and different texture but nevertheless demonstrated a pronounced anisotropy of strength. Aging increased the yield stress by about 80% and also inhibited twinning to some extent although the degree of anisotropy remained almost unaffected. The Mg–3Y alloy which showed a texture of intermediate strength was different in type from either of the others. Its strength behaviour was close to isotropic; in particular, no difference existed between tensile and compressive loading, and aging produced only a marginal increase in strength. Twins were relatively infrequent in the deformed Mg–3Y alloy but its mechanical behaviour could not be rationalised according to simple models.

Sensory specific satiety and intake : the difference between nibble- and bar-size snacks

The present study investigated (1) whether consumption of a nibble-size snack, as compared to a bar-size snack, leads to more sensory specific satiety (SSS) and a lower intake; and (2) whether attention to consumption, as compared to usual consumption, leads to more SSS and a lower intake. Subjects (N=59) tested two snack foods which differed in size, nibbles and bars, in two consumption conditions. In the attention condition, the instruction to chew the food well was given. In the control condition no such instruction was given. For each of the four SSS sessions ad libitum intake was measured and SSS scores were calculated. Mean intake of the nibbles was 12% lower than of the bars in the control condition, but not in the attention condition. Although non-significantly, attention to consumption tended to reduce intake of the bars but not of the nibbles. SSS scores were slightly higher for the bars than for the nibbles. Our results suggest that a smaller food size results in a lower intake. The data do not clearly support the idea that attention to consumption decreases intake. Hypothetically consumption of small foods and attentive consumption prolong the oral sensory stimulation, which results in a lower intake.

Effect of grain size on the performance of extruded magnesium alloy tubes in three-point bending

The performance of extruded AZ31, AZ61 and AM-EX1 tubes was examined in three-point bending. Different extrusion temperatures were used to investigate the effect of grain size on the load-carrying capacity, energy absorption and fracture propensity of the tubes. Results showed that while the peak load increased with a smaller average recrystallised grain size, the retention of large elongated un-recrystallised grains in the microstructure reduced the load. The presence of the large elongated grains also appeared detrimental to the ability of the tube to deform before fracture.

Combined in situ neutron diffraction and acoustic emission of twin nucleation & twin growth in extruded ZM20 Mg alloy

In the present work in situ neutron diffraction and acoustic emission were used concurrently to study deformation twinning in two ZM20 Mg alloys with significantly different grain sizes at room temperature. The combination of these techniques allows differentionation between the twin nucleation and the twin growth mechanisms. It is shown, that yielding and immediate post-yielding plasticity in compression is governed primarily by twin nucleation, whereas the plasticity at higher strains is governed by twin growth. The current results further suggest that yielding by twinning happens in a slightly different manner in the fine-grained as compared to the coarse-grained alloy.