Effect of Extrusion Cooking on Functional Properties and in vitro Starch Digestibility of Barley-Based Extrudates from Fruit and Vegetable By-Products

ABSTRACT:  Barley flour and barley flour–pomace (tomato, grape) blends were extruded through a co-rotating twin-screw extruder. The aim of the present study was to investigate the effects of die temperature, screw speed, and pomace level on water absorption index (WAI), water solubility index (WSI), degree of starch gelatinization, and in vitro starch digestibility using a response surface methodology. The selected extrudate samples were examined further using differential scanning calorimetry (DSC) and polarized light microscopy, respectively. The WAI of barley–pomace extrudates was affected by increasing pomace level. Temperature had significant effect on all types of extrudate but screw speed had significant linear effect only on barley and barley–grape pomace extrudates on degree of starch gelatinization. Although no gelatinization peak was detected, an endotherm was observed on all selected extrudates. In general, extrusion cooking significantly increased in vitro starch digestibility of extrudates. However, increasing level of both tomato and grape pomace led to reduction in starch digestibility.     

Changes in the biochemical and functional properties of the extruded hard‐to‐cook cowpea (Vigna unguiculata L. Walp)

Changes in the biochemical and functional properties of the hard‐to‐cook cowpea bean after treatment by the extrusion process are reported. The extrusion was carried out at 150 °C, with a compression ratio screw of 3:1, a 5‐mm die, and a screw speed of 150 r.p.m. The extrusion caused the complete inactivation of the α‐amylase and lectin and it also reduced the trypsin inhibitor activity (38.2%) and phytic acid content (33.2%). The functional properties were also modified by the process, an increase of 2.5 times in the water absorption index and 3.1% in the water solubility were observed. The digestibility of the hard‐to‐cook flour of the cowpea bean was improved after the extrusion, with a 55.9% increase in protein digestibility and a 5.9% increase in starch digestibility.     

Effect of lactic fermentation and extrusion of bean and pea seeds on nutritional and functional properties

Controlled lactic acid fermentation of „Bomba”︁ bean and „Opal”︁ pea was used to improved their nutritional and functional properties. The modified legumes were used as a source for extrusion process to obtain snack-type foods. Milled legume seeds were fermented by different population of Lactobacillus plantarum with different moisture content in plant material to estimate the influence of this two parameters on the dynamics of lactic fermentation. Quantitative and qualitative changes in carbohydrates and nitrogen compounds of modified seeds were analyzed (e.g . mono- and oligosaccharides, "in vitro" starch and protein digestibility). In the new snack-type products, functional properties: water solubility index (WSI), water absorption index (WAI), expansion index, bulk density and texture explained as a shearing stress were recorded. Results showed a distinct decrease in raffinose, verbascose and stachyose contents even up to 80 - 90% after fermentation and extrusion process. Lactic fermentation and extrusion of bean and pea seeds contributes to a significant (a ≤ 0,05) increase of "in vitro" protein and starch digestibility. Observations of changes in functional properties of extruderates (e. g., expansion, shearing stress, WSI, WAI) allowed to choose the most efficient model of fermentation pretreatment to obtain the best improvement of nutritional and functional features of the product.     

Chemical analysis and physico-chemical properties of chickpea and lentil cultivars

Some high yielding cultivars of chickpea (Kabuli and desi) (Cicer arietinum) and lentil (Lens esculenta) were used for chemical analysis and physico-chemical properties namely protein, fat, sugars, starch, in vitro digestibility of starch and protein; seed weight, seed volume, seed density, hydration capacity, swelling capacity, water absorption capacity and cooking time. Among chickpea, Gora Hisari (Kabuli) and Haryana Chana (desi) cultivars, and among lentil LH 82-6 cultivar manifested higher contents of protein, fat, sugars, starch and in vitro digestibility of starch and protein. Values of seed volume, seed density, hydration capacity, swelling capacity and water absorption capacity were also found higher for these cultivars which might have contributed towards less cooking time.     

Functional,biochemical and pasting properties of extruded bean (Phaseolus vulgaris) cotyledons

Response surface methodology was used to investigate the effects of extrusion conditions – namely moisture content (12.3–23.7 g 100 g^?1) and temperature (150–178 °C) – on physicochemical, antinutritional compounds, functional and pasting properties of extruded bean cotyledons. Results indicated that extrusion cooking did not change the chemical composition of bean flours, but completely eliminated the activity of the trypsin and α‐amylase inhibitors and haemagglutinins. The extrusion significantly improved starch and protein digestibility, water solubility and absorption of bean cotyledon. In addition, extrusion conditions significantly affected pasting properties, resulting in extrudate flours with different peaks and final viscosity values. From the results obtained in this work, it is possible to design a product with specific physicochemical, functional and nutritional properties using the appropriate moisture and temperature during extrusion.     

Physical and Functional Properties of Arrowroot Starch Extrudates

ABSTRACT:  Arrowroot starch, a commercially underexploited tuber starch but having potential digestive and medicinal properties, has been subjected to extrusion cooking using a single screw food extruder. Different levels of feed moisture (12%, 14%, and 16%) and extrusion temperatures (140, 150, 160, 170, 180, and 190 °C) were used for extrusion. The physical properties—bulk density, true density, porosity, and expansion ratio; functional properties such as water absorption index, water solubility index, oil absorption index, pasting, rheological, and textural properties; and in vitro enzyme digestibility of the extrudates were determined. The expansion ratio of the extrudates ranged from 3.22 to 6.09. The water absorption index (6.52 to 8.85 g gel/g dry sample), water solubility index (15.92% to 41.31%), and oil absorption index (0.50 to 1.70 g/g) were higher for the extrudates in comparison to native starch (1.81 g gel/g dry sample, 1.16% and 0.60 g/g, respectively). The rheological properties, storage modulus, and loss modulus of the gelatinized powdered extrudates were significantly lower ( P < 0.05) and these behaved like solutions rather than a paste or a gel. Hardness and toughness were more for the samples extruded at higher feed moisture and lower extrusion temperature, whereas snap force and energy were higher at lower feed moisture and temperature. There was a significant decrease in the percentage digestibility of arrowroot starch (30.07% after 30 min of incubation with the enzyme) after extrusion (25.27% to 30.56%). Extrusion cooking of arrowroot starch resulted in products with very good expansion, color, and lower digestibility, which can be exploited for its potential use as a snack food.     

Physicochemical,nutritional and functional properties of marama bean flour

Marama bean is a protein-rich, underutilised, drought-tolerant legume in sub-Saharan Africa. Its utilisation may be increased through value addition into protein-rich flours. Defatted flour from unheated and dry-heated (150 °C/20 min) whole marama beans (UMF and HMF) were analysed for physicochemical and protein-based functional properties. Heating significantly increased in vitro protein digestibility of marama bean flour. Of functional importance are the high levels of tyrosine present in marama bean flours. Heating significantly reduced protein solubility and emulsifying capacity of marama bean flours whilst water absorption capacity was improved. Foaming capacity was not affected by heating. UMF could be useful in food systems requiring high emulsifying capacity, but would not be suitable for applications requiring high water absorption and foaming capacity. Due to its high protein contents, marama bean flour could be used to increase the protein quality of cereal-based foods to help alleviate protein-energy nutrition in the region.     

Assessment of the techno-functionality,starch digestion rates and protein quality of rice flour–whey protein instant powders produced in a twin extruder

Whey protein concentrate (WPC) is an important raw material for the production of instant beverages due to its protein properties. A central composite design was devised to analyse the effects of thermoplastic extrusion of 2:1 rice flour:WPC blends in physical, chemical–nutritional and functional properties. Three main factors were selected, screw speed (225–375 r.p.m.), conditioning moisture (17%–23%) and temperature (120–180 °C) to evaluate effects on water absorption (WAI) and solubility (WSI) indexes, viscoamylograph cold and final viscosities, in vitro protein and starch digestibilities and starch hydrolysis indexes (HI). A second-order model showed that linear parameters were significant for all variables studies. Conditioning moisture affected properties more significantly than temperature and screws speed. The best treatment (16% moisture conditioning, 180 °C last barrel zone and screws rotating at 350 r.p.m.) in terms of water solubility had high starch in vitro digestibility and excellent protein quality determined in vitro and in vivo with weanling rats.     

Effect of Temperature on Properties of Extrudates from High Starch Fractions of Navy, Pinto and Garbanzo Beans

High starch fraction (HSF) isolated from three legumes were extruded at different temperatures. Extruded products were evaluated for expansion, density, color and some functional properties. The highest value of expansion was noted for pinto bean, and the lowest for garbanzo, extruded at 132°C. Extrudates from HSF expanded significantly (P < 0.05) less than corn extrudates. Oil absorption capacity increased slightly with increasing temperature and values were lower for navy and garbanzo beans than for pinto HSF and corn. Oil emul-sification capacity of- bean samples was about two times higher compared to corn. Water absorption index (WAI) of pinto and navy beans significantly increased (P < 0.05) from 110°C to 132°C.     

Effect of Extrusion Cooking on in Vitro Protein Digestibility of Sorghum

Extrusion variables including moisture (15 and 2.5%), temperature (50°, 125° and 200°C) and screw speed (50, 125 and 200 rpm) of two low tannin sorghum varieties extruded with 0, 2 and 4% calcium hydroxide were studied. Protein digestibility was determined by in vitro pepsin assay. Extrusion improved digestibility from 45.9 to 74.6% and 43.9 to 68.2% for the two varieties, respectively. Temperature was the key extrusion variable that influenced digestibility. Screw speed and moisture did not have significant effects. Alteration of pH before extrusion further improved digestibility.     

EXTRUSION BEHAVIOUR AND PRODUCT CHARACTERISTICS OF BROWN AND MILLED RICE GRITS

ABSTRACT

Extrusion behaviour of milled and brown rice grits obtained from six rice cultivars (Jaya, IR-8, PR-103, PR-106, Pusa No.1 and Basmati 385) was investigated using Brabender single screw extruder. Feed moisture of the grits was adjusted to 16%, and extrusion cooking was done at barrel temperature of 150°C and screw speed of 100 rpm. The milled and brown rice grits from different rice cultivars differed significantly with respect to extrusion behaviour and extrudate characteristi cs. Extrudates obtained from milled rice grits showed higher die pressure, expansion, water absorption index (WAI) and water solubility index (WSI) as compared to those from brown rice. WSI of extrudates varied from 3.38 to 10.5%, WAI from 5.20 to 6.90, die pressure from 6068 to 9325 kPa and expansion from 7.52 to 11.30 respectively. The grits from cultivars which had lower length-breadth ratio and mealy endosperm resulted into more expanded extrudates and hence were found to be more suitable from extrusion.     

Effect of processing conditions on some functional characteristics of extrusion‐cooked cassava starch/wheat gluten blends

Extrusion‐cooked blends of cassava starch (CS) and wheat gluten (WG) were studied. The data were analysed using response surface methodology. The results showed the formation of new structures characterised by lower radial expansion (RE) and specific volume (SV) when gluten was added to CS. WG content was the most important variable affecting RE, water absorption index (WAI), water solubility index (WSI), SV and difference in colour (ΔE) of the extruded products, but feed moisture content and barrel temperature also influenced RE. WAI was affected by a significant interaction between WG content and barrel temperature. The extruded products had lower WAI values and higher WSI values than WG‐free products. Heat, high shear rate and high pressure during extrusion cooking caused mechanical destruction or denaturation of the WG and gelatinisation and dextrinisation of the starch components. The extruded blends could have diverse applications. © 2002 Society of Chemical Industry     

Effects of Extrusion Process Variables on Quality Properties of Wheat-Ginseng Extrudates

The present study investigated the effects of extrusion process variables (feed moisture, screw speed, and barrel temperature) on the physical [expansion ratio, water absorption index (WAI), and water solubility index (WSI)], pasting, and thermal properties of wheat-ginseng extrudates (WGE). A wheat flour-ginseng powder (GP) blend (10% GP, w/w) was extruded in a twin-screw extruder (L/D ratio of 25:1) with full factorial combinations of feed moisture (25, 30, and 35%), screw speed (200 and 300 rpm), and zone 5 barrel temperature (110, 120, 130, and 140°C). The expansion ratios of WGE were significantly increased with decreasing feed moisture, decreasing screw speed, and increasing barrel temperature. Increasing feed moisture significantly increased WAI values of WGE and significantly decreased WSI values of WGE. However, an increase in either screw speed or barrel temperature caused a significant decrease in WAI values of WGE and a significant increase in WSI values of WGE. Rapid visco analyzer peak viscosity values of WGE were significantly affected by changes in extrusion process variables studied, indicating that the degree of starch degradation and/or gelatinization in WGE is a very important factor associated with their peak viscosity. WAI values of WGE were positively correlated (r = 0.88, p ≤ 0.001) with peak viscosity values of WGE samples, whereas WSI values of WGE samples were negatively correlated (r = 0.82, p ≤ 0.001). Increasing feed moisture resulted in an increase in values of transition peak temperature (T_p) of WGE, whereas increasing screw speed and barrel temperature each led to a decrease in T_p values of WGE, determined by differential scanning calorimetry.     

Effect of extrusion on nutritional quality of maize and Lima bean flour blends

Maize flour (Zea mays) (M), Lima bean flour (Phaseolus lunatus) (B) and blends of these in proportions of 75M/25B, 50M/50B and 25M/75B (w/w) were extruded and their nutritional quality evaluated. Extrusion was done with a single screw extruder at 160 °C, 100 rpm and 15.5% moisture. In vitro protein digestibility (87%) was higher in the extruded products. Available lysine and resistant starch were highest in 50M/50B raw flour (59.5 g kg⁻¹ protein, 67.9 g kg⁻¹, respectively) but decreased after extrusion (45.5 g kg⁻¹ protein, 16.6 g kg⁻¹, respectively). The same treatment had the lowest available starch (561.6 g kg⁻¹ flour, 507.9 g kg⁻¹ extrudate). Total dietary fiber in the 50M/50B raw flour blend was 144 g kg⁻¹ versus 176 g kg⁻¹ in its extrudate. This was most noticeable for soluble dietary fiber, which increased from 10.6 g kg⁻¹ to 79.4 g kg⁻¹ after processing. Extrusion of blends is feasible up to a 50% bean inclusion level, which improves the nutritional value of the expanded product.Copyright © 2006 Society of Chemical Industry     

Influence of extrusion variables on the protein in vitro digestibility and protein solubility of extruded soy tarhana

Tarhana, supplemented with 150 g kg⁻¹ full‐fat soy flour, was extruded at different extrusion conditions (barrel temperature: 80–120°C; screw speed: 100–300 rpm; feed rate: 10–20 kg h⁻¹ ) using a twin‐screw extruder. The effect of extrusion conditions on the in vitro digestibility (PD) of the protein and protein solubility (PS) was investigated using response surface methodology. Regression equations for predicting PD and PS were developed. While the barrel temperature had a significant effect on PD (P <0.1), feed rate was the most significant variable on PS of the samples (P<0.05). Since the protein solubility should be high for the instant properties of extruded soy tarhana soup, it is suggested that soy tarhana should be extruded at low feed rates (ie high residence times) while high barrel temperatures should be achieved for the inactivation of antinutritional factors present in the soy flour. © 1999 Society of Chemical Industry     

Physico-chemical and sensory quality of extruded light red kidney bean (Phaseolus vulgaris L.) porridge

A laboratory co-rotating twin-screw extruder was used to study the effect of extrusion conditions on physical, chemical, and sensory characteristics of extruded light red kidney beans (Phaseolus vulgaris L). Raw bean flour was extruded at 25 g/100g and 36 g/100g moisture content. Other extrusion parameters were: barrel temperatures, 120 °C/105 °C (BT-1) and 130/115 °C (BT-2); screw speeds, 118 rpm (SS-1), 194 rpm (SS-2), and 253 rpm (SS-3); and feed rates of 80 and 120 g/min (FR-1 and FR-2, respectively). Extrudates were analyzed for expansion ratio (ER), bulk density (BD), water absorption index (WAI), water solubility index (WSI), and lectins, as phytohemagglutinin (PHA) activity. Sensory evaluation of bean porridge, obtained after coarsely grinding extrudates, was done to compare it to Sosuma, a traditional Rwandan porridge. Feed rate significantly influenced average ER, which was determined to be 1.22 and 1.30 for FR-1 and FR-2, respectively. Increasing moisture content from 25 g/100g to 36 g/100g significantly increased average BD. The WAI and WSI values did not show a clear trend under extrusion conditions used in this study. For all extruded samples, lectin was reduced to less than one-tenth of that in the raw beans. Sensory evaluation of bean porridge, on a 1-9 hedonic scale (1 = dislike extremely and 9 = like extremely), exhibited scores of 7.65, 7.69, 6.25, and 6.94 for color, texture, flavor, and overall acceptability, respectively.     

蛹虫草复合谷物杂粮膨化产品的工艺优化及糊化特性

目的：采用双螺杆挤压工艺制备蛹虫草复合谷物杂粮膨化产品,并研究蛹虫草对谷物杂粮膨化产品淀粉糊化特性的影响。方法：以大米粉、糯米粉、薏米粉、红豆粉、黄豆粉、蛹虫草粉为原料,按照一定比例混合制成蛹虫草复合谷物杂粮粉进行挤压膨化实验,并在单因素试验的基础上,选择物料水分含量、螺杆转速、进料速率、挤压温度为影响因素,产品径向膨化率、糊化度、水分含量、吸水性和水溶性指数为指标,设计正交试验,用极差分析法优化出蛹虫草复合谷物杂粮膨化产品的最佳工艺,并利用快速黏度仪测定谷物杂粮膨化产品和蛹虫草复合谷物杂粮膨化产品的淀粉糊化特性。结果：蛹虫草复合谷物杂粮膨化产品的最优工艺参数为物料水分含量16%、螺杆转速180 r/min、机筒的5 段挤压温度80-90-120-140-165 ℃、进料速率15 r/min,此时蛹虫草复合谷物杂粮膨化产品的径向膨化率、糊化度、水分含量、水溶性和吸水性指数分别为3.015、84.32%、6.11%、29.65%、416.39%;与谷物杂粮膨化产品相比,蛹虫草复合谷物杂粮膨化产品峰值黏度、保持黏度、最终黏度、回生值显著下降。结论：蛹虫草复合谷物杂粮膨化产品挤压工艺可行,添加蛹虫草能够显著降低谷物杂粮膨化产品的糊化特征值,并抑制其淀粉分子的回生或重排。     

Effect of extrusion conditions on the physicochemical properties of a snack made from purple rice (Hom Nil) and soybean flour blend

Soy flour was added at levels of 5%, 10%, and 15% of Hom Nil rice flour for extrusion at 190 °C barrel temperature and 350 rpm screw speed. The extruded snack qualities decreased inversely with soy flour. However, product qualities were considered to be optimised when soy flour at 5% was added. The effect of feed moisture content (15, 17, 19 g (100 g)^?1 wb), barrel temperature (150, 170, 190 °C) and screw speed (350, 400, 450 rpm) on physicochemical properties of the snack were then investigated. The physicochemical properties of the product including expansion ratio, density, water absorption index (WAI), water solubility index (WSI) and hardness were evaluated. All properties were related, as linear equations, in terms of feed moisture content, barrel temperature, screw speed with relative correlation (R²) at 0.83–0.94. The snack properties along with consumer acceptance were all highest when the extruded condition were 15 g (100 g)^?1 wb feed moisture content, 170 °C of barrel temperature and 450 rpm of screw speed.     

Extrusion of Hulled Barley Affecting β-Glucan and Properties of Extrudates

Grits from eight different hulled barley cultivars were subjected to extrusion cooking on a twin screw extruder, and the effect of extrusion variables (temperature and moisture) on β-glucan and physicochemical properties was evaluated. The highest bulk density was observed for extrudates extruded at 150 °C and 20% moisture (low temperature high moisture, LTHM) while the highest expansion was observed for the extrudates extruded at 150 °C and 15% moisture (low temperature low moisture). Extrusion reduced the lightness (L*) of the extrudates and the highest decrease observed for LTHM extrudates. Increasing the feed moisture decreased water solubility index (WSI) significantly while increasing the extrusion temperature significantly increased WSI. The high temperature high moisture (HTHM) extrudates exhibited the highest water absorption capacity. The total β-glucan content was not affected by extrusion cooking, but a significant increase in soluble β-glucan was observed with the highest in high temperature low moisture extrudates. The ratio of soluble to insoluble β-glucan varied from 0.7 to 1.5 in the control barley, but after extrusion cooking, the ratio was changed from 1.2 to 3.1. The β-glucan extractability increased by up to 8% after extrusion with extrudates from HTHM showing the highest extractability. The extent of starch gelatinization varied from 80% to 100% upon extrusion, and the highest was observed in HTHM extrudates. A significant decrease in the peak and final viscosity of the extrudates at all the extrusion conditions was observed.     

挤压处理对豌豆淀粉的流变特性和体外消化率的影响

目的：研究挤压条件（豌豆淀粉水分质量分数：25%、35%、40%、45%和55%;剪切温度：50、60、70、80 ℃和90 ℃;螺杆转速：100、120、140、160 r/min和180 r/min）对豌豆淀粉的体外消化率和流变特性的影响。方法：采用体外消化法测定了豌豆淀粉的水解度,并通过稳态剪切实验、频率扫描实验和温度扫描实验测定了豌豆淀粉的流变特性。结果：挤压后水解度和慢消化淀粉（slowly digestible starch,SDS）相对含量增加,抗性淀粉（resistant starch,RS）相对含量降低;在水分质量分数为25%的条件下（螺杆转速140 r/min、剪切温度70 ℃）,SDS相对含量最高,为34.41%;在螺杆转速为180 r/min时（水分质量分数40%、剪切温度70 ℃）,RS相对含量最低,为10.49%。粒径与SDS相对含量和稠度系数K呈显著正相关（P＜0.05）,相关系数分别为0.60和0.61。挤压的豌豆淀粉溶液为假塑性流体;在频率和温度扫描实验中,储存和损耗模量随豌豆淀粉挤压损坏程度增加而增加。结论：挤压后的豌豆淀粉结构增强并表现出弹性凝胶特性。因此,挤压工艺可能通过影响豌豆淀粉的体外消化率和流变性能来改善食品的功能性和品质。