Effects of process variables and addition of polydextrose and whey protein isolate on the properties of barley extrudates

Extrusion cooking is commonly used in the production of snacks. In the present study, extrudates were prepared using barley flour alone and with the addition of either polydextrose (PD) or whey protein isolate (WPI) and both PD and WPI. Independent process variables were water content of the mass (17%, 20% and 23%), screw speed (200, 350 and 500 rpm) and temperature of section 6 and die (110, 130 and 150 °C). Expansion, hardness, water content, porosity and chemical composition of the extrudates were analysed. Highly porous and expanded snack products with high dietary fibre and protein contents were obtained from barley flour and WPI when water content of mass was 17%, screw speed 500 rpm and temperature of section 6 and die 130 °C. Barley flour alone or with PD resulted in hard and non‐expanded extrudates. Expansion of extrudates was statistically significantly increased with decreasing water content of the mass and increasing screw speed in all trials.     

Effects of potato starch on the characteristics,microstructures and quality attributes of indica rice flour and instant rice noodles

The effects of partial replacement (0%–20%, w/w) of rice flour by potato starch (PS) on the physicochemical properties, microstructures, texture and in vitro digestibility of indica rice flour (IRF) and instant rice noodles (IRN) were systematically investigated. Accordingly, the addition of PS significantly increased the peak viscosity (2876.00–3221.00 mPa·s) and tan δ values (0.14–0.22) but lowered the setback values (2169.00–1036.50 mPa) of the pastes. Rice noodles with 5%–15% PS (PS and IRF at the mixing ratios of 5:95, 10:90, 15:85 and 20:80, respectively) addition exhibited modulated appearance and textural properties. The mutually exclusive phosphate groups of PS facilitated the expansion of starch granules, contributing to the formation of more compact microstructure and higher-ordered crystalline structures (confirmed by scanning electron microscope and X-ray diffraction), endowing rice noodles with better cooking and digestive attributes, and visibly increased slowly digestible starches content (26.09%–31.34%). The quality attributes of rice noodles could be accurately predicted by the physicochemical properties of rice flour referring to Pearson’s correlation analysis. The study demonstrates that the blending of PS is both an effective and economical pathway in improving the nutritional and textural properties of IRN.     

Quality attributes and rheological properties of novel high milk protein-based extrudates made by supercritical fluid extrusion

Supercritical fluid extrusion (SCFX) process has opened up a new way of extruding heat-sensitive materials such as milk protein concentrate (MPC) into novel nutritional porous extrudates. Three formulations (30%:66.5%, 60%:36.5% and 90%:6.5% of MPC: rice flour, w/w) with 1% Dimodan, 1% lecithin and 1.5% salt were extruded by using SCFX. The physical, rheological and thermal properties of the extrudates were evaluated. The results showed that the increased MPC contents decreased gelatinisation enthalpy and increased the viscosity of the extrudates, which contributed to develop stable porous extrudates; and the increased MPC contents also helped to form a stronger gel network existed in dispersion of the extrudate samples, which resulted in a higher stress to break the gel and flow. The radial and overall expansions, crispness, porosity, rehydration ratio, moisture content and water activity increased while the axial expansion, hardness, piece density, apparent density, bulk density, decreased with higher amounts of MPC contents in extrudates. The overall results indicated that 90% MPC-containing extrudate was very suitable for developing highly nutritional and healthy cereals/snacks.     

Gluten-free cakes with walnut flour: a technological,sensory, and microstructural approach

Walnut flour (WF), a by-product of walnut oil production, is characterised by high polyunsaturated fatty acids, proteins, and fibre contents and presents suitability for bakery products. However, when using non-traditional ingredients, it is essential to evaluate the effect on the quality properties of the final product. So, this work aimed to assess the impact of WF on the technological, physicochemical, and sensory properties of gluten-free (GF) cakes. WF was added at a flour blend (cassava (CS) and maize (MS) starches and rice flour) at 0, 10%, 15%, and 20%. The results showed that WF modified starch gelatinisation, increased amylose–lipid complex (ALC) content, and made crumbs easier to chew. Besides, the total dietary fibre (TDF) and protein content significantly increased. Cakes with 15% WF presented the highest specific volume (SV) and no differences in overall acceptability with respect to control. Hence, WF is a suitable ingredient for gluten-free bakery products.     

BAKING PERFORMANCE AND CONSUMER ACCEPTABILITY OF RAW AND EXTRUDED COWPEA FLOUR BREADS

Cowpea flour was used to partially replace wheat flour in yeast bread, using automatic household‐type bread machines for mixing, proofing and baking. Loaves containing 15 or 30% extruded cowpea flour weighed more (683.4 g) than loaves from other treatments (641.1–652.6 g). The 100% wheat had the highest loaf volume (2.58 L) and the 30% extruded cowpea the lowest (1.64 L). Cowpea flour breads contained more protein (13.9–15.4%) than the 100% wheat (4.1% fat, 12.5% protein). Bread made with 15% extruded cowpea flour was not different (P < 0.05) from the all‐wheat control in sensory quality and acceptability. Hedonic ratings for the control and 15% extruded cowpea flour ranged from 6.6 (like slightly) to 7.4 (like moderately) for all sensory attributes. The least liked samples contained either 30% raw or 30% extruded cowpea flour, receiving ratings for all attributes ranging from 4.8 (disliked slightly) to 6.2 (liked slightly). Overall, 15% extruded cowpea flour demonstrated successful bread making performance without compromising sensory quality.     

Development of protein-Rich Sorghum-Based Expanded Snacks Using Extrusion Technology

Sorghum is an important staple crop in semi-arid regions of Africa and India because of its drought tolerance. But low protein content and quality limit its widespread use. This project focused on developing sorghum-based extruded snacks. Results from preliminary lab-scale extrusion experiments were used to design a 2×5 factorial pilot-scale study. Two blends of sorghum flour and corn flour were prepared (6:1 and 5:2 w/w ratios) as the controls. Three different sources of protein—whey protein isolate, defatted soy flour, and mixed legume flour—were added to the sorghum/corn flour blends at 30%. A 50:50 blend of defatted soy flour and whey protein isolate was also added at 30% to the sorghum/corn flour blends. The resultant ten formulations were extruded on a pilot-scale twin-screw extruder to investigate the effects of sorghum/corn flour ratio and protein addition on product expansion, microstructure, mechanical properties, and sensory attributes. Expansion ratio of extruded product increased at the higher level of corn flour, and decreased with the incorporation of protein sources. Extrudates with defatted soy flour had a lower expansion ratio (5.3–5.4) than those with whey protein isolate (7.7–7.9), legume flour (7.1–9.9), or whey protein isolate-defatted soy flour (6.1–6.9). Extrudate microstructure, obtained by X-ray microtomography, corresponded well with expansion characteristics. Extrudates with defatted soy flour had the lowest cell diameter. Average crushing force (ranging from 40.9 to 154.87 N) was lower for extrudates with a higher level of corn flour. However, contrary to expectations, crushing force and crispness work both decreased with incorporation of protein sources. Consumer acceptability results showed that the addition of protein sources enhanced taste and overall acceptability of the extruded snacks, with the treatment sorghum/corn flour 5:2 and whey protein isolate-defatted soy flour as the protein source having significantly higher ratings than the other treatments.     

Development And Characterization of Extruded Fura From Mixtures of Pearl Millet and Grain Legumes Flours

Dehulled pearl millet flour (100%) and blends of pearl millet, cowpea, groundnut and soybean flours at 80:20, 70:30 were extruded at 30 g moisture/100 g sample using a Brabender Laboratory single screw extruder to develop extruded fura products. The fura extrudates and fura produced in the traditional way were analyzed for their physical and chemical and sensory properties. There were significant differences (p < 0.05) in the puff ratio of the extruded fura products. Pearl millet: cowpea (80:20) fura had the highest puff ratio (4.71) while the pearl millet: groundnut (80:20) fura had the lowest (2.90). The bulk density of the pulverized extruded fura was lower than that of the dried and pulverized traditional fura. The hydration power of the extrudates increased significantly (p < 0.05) at 28°C and 50°C. Extrusion increased the hydration power of products. Fura extrudate containing 100% pearl millet flour had the highest hydration power of 63.9% at 28°C, while the traditional fura had the lowest of 15.8% at 28°C. Protein content of samples increased with supplementation of pearl millet with grain legumes. Sensory evaluation results showed that there were no significant differences among the fura extrudates and the traditional fura with respect to color, texture and overall acceptability except for flavor. Extruded products were still acceptable after 12 weeks storage in polyethylene and cellophane bags at 30 ± 2°C. Extrusion and supplementation processes are therefore one way of producing a convenient shelf stable nutrient rich fura in the areas where fura is commonly consumed.     

QUALITY IMPROVEMENT OF IDLI USING EXTRUDED RICE FLOUR

The effect of substituting rice with extrusion cooked (75, 100 and 125C) rice flour at 10, 20, 30 and 40% level on the quality of idlis was investigated. Both the levels of substitution and temperature of extrusion had significant effects on the specific gravity, acidity and pH of the idli batter, and textural and sensory quality of the idlis. The idlis prepared from idli mix containing rice substituted by 20–30% of rice flour extruded at 125C were most acceptable.     

Development and characterization of extruded snacks from New Zealand Taewa (Maori potato) flours

Crispy extruded snacks were prepared by mixing ungelatinized dried potato flours from four different Taewa cultivars and a modern potato cultivar with corn flour at two different ratios (25:75; 50:50), and their quality characteristics studied. All of the potato flours showed differences in colour, dry matter content, starch content and pasting characteristics. Among the extrudates prepared with 25% potato flours, Huakaroro snacks showed an L¹ value of 51.71, whereas pure corn flour snacks had the highest L¹ value of 61.22. The b¹ at both levels of potato flour incorporation were lowest for Tutaekuri snacks. The microstructural characteristics of the extrudates such as cell structure and cell wall thickness changed considerably when potato flour was incorporated (50%) in the extruder feed. Moemoe, Tutaekuri and 100% corn flour snacks had the highest toughness, whereas the highest crispness was observed for the Huakaroro snacks. Lower and higher cold peak viscosities of 91 and 597 cP were observed for corn and Tutaekuri extrudates (in powdered form), respectively. The extrudates with 50% potato flour had higher breakdown and lower final viscosity than those containing 25% flour. The peak G′ values were highest for 100% corn, Moemoe and Karuparera snack pastes.     

Effect of guar gum content on some physical and nutritional properties of extruded products

The effect of guar gum (0-10%) added to flour (maize, potato, rice, and wheat) prior to extrusion on the microstructure, physical properties (texture, expansion, density, pasting) and nutritional properties (starch digestibility) was investigated. The inclusion of guar gum did not decrease starch digestibility; rather, at 10% guar gum rapidly digestible starch increased by 24%, 15%, 25% and 43%, in maize, potato, rice and wheat flour-based products, respectively. In general, increases in starch digestibility appear to be related to the weaker microstructure (i.e., lower textural hardness), larger matrix surface area, and lower viscosity (pasting properties) of extrudates containing guar gum. These results suggest that microstructural changes affect the starch digestibility of extrudates; nevertheless, probably other factors such as particle size during digestion may also play an important role.     

Organoleptic and nutritional evaluation of wheat breads supplemented with soybean and barley flour

Supplementations of soy (full fat and defatted) and barley flours to wheat flours at 5, 10, 15 and 20% levels were carried out to test the effects on organoleptic and nutritional evaluation of the supplemented bread. Additions of 15% barley flour, 10% soy flour (full fat and defatted), 15% barley plus full fat soy flour and 15% barley plus defatted soy flour to wheat flour produced acceptable breads. However, substitution of soy (full fat and defatted) and barley flours to wheat flour separately and in combinations at 20% levels did not produce organoleptically acceptable bread. Various nutritional parameters, such as protein, fat, total lysine, protein digestibility (in vitro), sugars, starch digestibility (in vitro), total and available minerals, antinutrients, dietary fibre and β-glucan were determined in supplemented and control bread. Increasing the level of substitution from 5 to 10% of full fat and defatted soy flour to wheat flour significantly (P<0.05) increased protein (from 12.1 to 13.7 and 12.4 to 13.8%), lysine (from 2.74 to 3.02 and 2.76–3.05 mg/100 g protein) and total calcium (from 70.2 to 81.4 and 71.9–81.8 mg/100 g) contents. However, there was also an increase in phytic acid (238–260 and 233–253 mg/100 g), polyphenol (324–331 and 321–329 mg/100 g) and trypsin inhibitor activity (193–204 and 193–198 TIU/g). When barley flour was substituted separately, and in combinations, with full fat and defatted soy flour up to 15%, this significantly increased the contents of protein, total lysine, dietary fibre and β-glucan. It may be concluded that breads supplemented with barley and defatted soy flour, up to a 15% level, are organoleptically and nutritionally acceptable.     

The effect of rice bran on physicochemical,textural and glycaemic properties of ready-to-eat extruded corn snacks

In this work, corn extruded snack products were enriched with rice bran (RB) at 10% and 15%. A co-rotating twin-screw extruder was used with a feed moisture content of 16 g 100 g⁻¹, a screw speed of 240 r.p.m. and four heating sections of the barrel (100, 140, 150 and 150 °C). The impact of RB inclusion on nutritional profile, starch digestion, physicochemical and textural properties of snack products was evaluated. RB-enriched extrudates showed a lower specific volume and hardness and higher crispness than control. RB at 15% gave a water-holding capacity lower than control. Rheology of extrudate dispersions indicated an increase in elastic interactions and solid-like behaviour with RB supplementation. Differences in rheological properties resulted in attenuation of predictive glycaemic response for RB-enriched snacks.     

Effects of water requirement and substitution level on wheat–rice noodles with hydrocolloids

Substitution of wheat flour with rice flour in noodles can increase rice flour utilization, reduce cost, and lower the allergenicity of wheat gluten. High‐AM rice flour (32.5%) was used to dilute high‐protein wheat flour (14.8%) on account of its excellent gel‐forming properties. Target noodles should obtain qualities comparable to noodles made from all‐purpose wheat flour (10.4% protein). RSM technique was applied for optimization of substitution level, water requirement and hydrocolloid level. The coefficient of determination (R²) showed that only substitution level and water requirement could predict textural characteristics and lightness (L*) of cooked noodles. Increased amounts of rice flour resulted in a decrease in all cooked noodle textural qualities but an increase in L*. Water absorption of rice flour was significantly higher than that of wheat flour; therefore, increased water content of substituted wheat noodles was necessary. However, water requirement should correspond well with rice substitution level. CMC was observed to be more appropriate for use in wheat–rice noodles. Wheat–rice noodles were not significantly different from wheat noodles at 30–47% substitution, water requirement 43.5–59%, and 1.2–1.5% CMC. The addition of 1.5% Na₂CO₃ resulted in a significant improvement in cooked wheat–rice noodle texture (p ≤ 0.05).     

Development of healthy extruded maize snacks; Effects of soybean flour and feed moisture content

The main aim of this research was to introduce a green and clean method of increasing the nutritional quality while preserving the quality of extruded maize snacks. This was achieved by addition of soybean flour (5%, 10%, 15% and 20%, w/w) as a source of plant protein, fibre and bioactive compounds and changing the feed moisture content. Extruded samples were produced using a single-screw extruder. Increasing the soybean flour and feed moisture content resulted in reduced specific mechanical energy of the extruder and consequently several changes in physicochemical properties of the snacks including higher moisture content, lower expansion and volume, reduced crispiness, reduction in L-and a-values but an increase in b-value and formation of more wrinkly and thicker air bubbles cell walls as observed under scanning electron microscope. The addition of <20% soybean flour and feed moisture content resulted in snacks with improved nutritional value and physical properties.     

Role of pulses to modulate the nutritive,bioactive and technological functionality of cereal-based extruded snacks: a review

Pulses hold excellent nutritive potential owing to high-quality protein content, dietary fibre, minerals, vitamins, oligosaccharides, polyphenols, tannins, phytosterols and several other bioactive constituents. These bio-functional compounds impart significant health benefits by reducing the risk of several chronic complications such as hypertension, cancers, cardiovascular diseases and neurological concerns mainly through anti-oxidative and radical scavenging mechanisms. These high protein ingredients when added to cereal-based extruded snacks not only enhance the nutritive and bioactive profile of the resultant snacks but also modulate the techno-functional attributes of the extrudates. Protein interactions with cereal-based starch and other constituents result in structural variation at the macromolecular level consequently varying the physical, mechanical and techno-functional properties including expansion ratio, bulk density, hydration properties, pasting characteristics and texture. The present review aimed at elaborating the nutritive and bio-functional potential of pulses enriched cereal-based expanded snacks. Further, significant emphasis has been given to the impact of pulse flour incorporation on functional, structural and mechanical properties of the cereal-based extrudates.     

Effect of king palm (Archontophoenix alexandrae) flour incorporation on physicochemical and textural characteristics of gluten-free cookies

The replacement of the blend of rice flour (70%) and corn starch (30%) with king palm flour [ Archontophoenix alexandrae (F. Muell.) H. Wendl. and Drude] at levels of 0–30% was investigated for its effects on the chemical and physical characteristics of gluten-free dough and cookies. Cookies containing 10, 20 and 30% of king palm flour were analysed by twenty-one celiac consumers through preference-ranking test. Ash, minerals, and dietary fibre contents increased in cookies that were added with king palm flour. Compared with the control dough, the incorporation of king palm flour increased the firmness and decreased the adhesiveness of dough samples. The incorporation of king palm flour increased the hardness of cookies in relation to the control dough. None of the cookies differed significantly ( P  > 0.05) in the lightness (L*) parameter. All formulations produced cookies with hue angles around 60, which indicate a tendency to brown colour. The study reveals that the incorporation of king palm flour showed desirable results in nutritional characteristics, because of the increase of the dietary fibre and minerals contents. In this study, the cookies preferred by celiac consumers were those containing 10 and 20% of king palm flour ( P  > 0.05).     

Organoleptic and shelf stability analysis of legume based gluten free snacks: its biochemical and immunochemical validation

Deep-fried Gluten free snacks were prepared using the composition of legumes flours with commercially available starches and evaluated for their proximate composition, nutritional quality and sensory properties. The maximum reduction in peak viscosity (414 BU) of blends was observed compared to refined wheat flour (860 BU). Proximal analysis indicated, protein content was improved from 6% (wheat snack) to 17% (red cowpea based snack) and also increased in mineral content such as iron and calcium. Difference in the iron content with highest in white cowpea based snack (FSW) (9.2 mg%), whereas calcium content was highest in red cowpea based snack (FSR) (65.5 mg%). On the basis of storage studies, there was a significant reduction in the crispiness indicated by instrumental and sensory analysis. The highest PV obtained for FSW and FSR was recorded to be 1.2 and 1.48 respectively at 30 days. Free fatty acid increased in all the three i.e. field bean based snack (FSF), FSW, FSR from 0.13, 0.12 and 0.13 to the highest of 0.35, 0.5 and 0.48 respectively at 0–60 days. Fat content in FSF, FSW and FSR decreased from 10.35 to 8.9%; 13.6–8.9% and 14.5–7.8%. Gluten free confirmation was carried out in the developed snacks by immunochemically. Immunochemical validation showed that, the extracted proteins were not reacted to wheat gliadin antibodies. Hence, the developed legume flours based gluten free snacks can be included in the diet of non-allergic to gluten sensitive population.     

COMPUTER OPTIMIZATION OF WEANING FOOD FORMULAS

Low cost protein/energy rich weaning foods suitable as supplements to human milk that satisfy the nutritional requirements for 6–12 month infants were designed for the Egyptian market. Three formulas were optimized with Brill Formulation Software using FAO/WHO weaning food recommendations. Selected least cost formulations included: Formula #1: 38.5% wheat flour, 19.4% cowpea flour, 14.8% sesame flour, 15% NFDM, 7.3% cottonseed oil and 5% sucrose; Formula #2: 23.3% wheat flour, 35.1% cowpea flour, 21.6% sesame seeds, 15% NFDM and 5% sucrose; Formula #3: 29.9% wheat flour, 35% cowpea flour, 16.6% sesame flour, 5.25% NFDM, 7.9% cotton seed oil and 5% sucrose. Each formula contained about 20% protein, 400 Kcal/100 g and sufficient amounts of essential amino acids. The extrusion process did not affect the nutrient composition of the weaning food formulas.     

Effect of mustard flour incorporation on nutritional, textural and organoleptic characteristics of biscuits

Nutritional, sensory and textural characteristics of defatted mustard flour fortified biscuits were studied to optimize the mustard flour supplement in the blend for making biscuits. The wheat flour was replaced by defatted mustard flour at 5, 10, 15 and 20% incorporation levels in biscuit preparation. The protein content of mustard flour biscuit increased nearly 2.5 times as a result of mustard flour incorporation, coupled with reduction in fat and an increase in fiber content. Sensory evaluation results revealed that the sample containing 15% defatted mustard flour scored highest in most of the attributes including overall acceptability. Textural characteristics of all dough and biscuit upto 15% supplement of defatted mustard flour were similar while at 20% level, the values were significantly different. The study reveals that incorporation of 15% defatted mustard flour gave desirable results in terms of nutritional, sensory and textural attributes of mustard fortified biscuits.     

Incorporation of whey products in extruded corn,potato or rice snacks

Sweet whey solids (SWS) or whey protein concentrate (WPC) were added at concentrations of 250 and 500 g/kg to corn meal, rice or potato flour to make snack products. Extrusion processing conditions included low shear, high shear, and the combination of high shear/low moisture. Increased specific mechanical energy (SME) was desired for expanding products, but SME was reduced as a result of incorporating WPC and SWS. Quality indices for expansion and breaking strength decreased significantly (P<0.05), indicating poor textural effects. By reducing the moisture and adding reverse screw elements, SME was increased, which increased product expansion and breaking strength.