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1.
Mixtures of sweet potato flour and soy flour were made in a pilot mixer. They were moisturized with 18, 25, and 30% water and extruded in a single screw extruder at 80 rpm, using a die of 6mm. Extrusion temperature was maintained at 100 +/- 3 degrees C. Effects of adding soy flour into sweet potato flour, as well as variation in feed moisture on the composition and some functional properties of the extrudates were investigated. Increase in sweet potato content increased carbohydrate values. Protein increased with increase in soy flour. Feed moisture did not significantly (p < or = 0.05) affect extrudate composition. Increase in sweet potato content and feed moisture increased expansion ratio. Bulk density decreased with decrease in feed moisture, but increased with increase in soy flour. Starch content increased as sweet potato content increased. Degree of gelatinization increased with sweet potato content. Lower feed moisture enhanced gelatinization. Water absorption index (WAI) increased as sweet potato content increased. Feed moisture had a slight effect on WAI and water solubility index (WSI). Amylose increased with increase in sweet potato content. Increase in soy flour led to an increase in yellowness (b*) of extrudates.  相似文献   

2.
The physical properties and microstructure of corn meal extruded with soy fiber, salt, and sugar were studied using an intermeshing and co-rotating twin-screw extruder. The effects of fiber, sugar and screw speed on water absorption index (WAI) and water solubility index (WSI) correlated well with bulk density and specific volume of extrudates. Increasing screw speed decreased WAI but increased WSI. Increasing fiber content from 0–20% lowered the WAI, but increased the WSI. The trends were reversed with further increases in fiber content. An increase in the sugar content reduced WSI. Scanning electron microscopy revealed that increasing fiber, sugar contents, and screw speed resulted in less expanded extrudates with smaller air cell size and thicker cell walls. The breaking strength increased with increasing sugar and fiber contents and was negatively correlated with the radial expansion of extrudates. Salt (0–2%) had no significant effects on the WAI, WSI, and microstructure of extrudates.  相似文献   

3.
Mixtures of sweet potato flour and soy flour were made in a pilot mixer. They were moisturized with 18, 25, and 30% water and extruded in a single screw extruder at 80 rpm, using a die of 6mm. Extrusion temperature was maintained at 100 ± 3°C. Effects of adding soy flour into sweet potato flour, as well as variation in feed moisture on the composition and some functional properties of the extrudates were investigated. Increase in sweet potato content increased carbohydrate values. Protein increased with increase in soy flour. Feed moisture did not significantly ( p 0.05) affect extrudate composition. Increase in sweet potato content and feed moisture increased expansion ratio. Bulk density decreased with decrease in feed moisture, but increased with increase in soy flour. Starch content increased as sweet potato content increased. Degree of gelatinization increased with sweet potato content. Lower feed moisture enhanced gelatinization. Water absorption index (WAI) increased as sweet potato content increased. Feed moisture had a slight effect on WAI and water solubility index (WSI). Amylose increased with increase in sweet potato content. Increase in soy flour led to an increase in yellowness (b*) of extrudates.  相似文献   

4.
The effects of extrusion conditions on cooking degree, flour dispersion viscosity and mineral potential availability of extruded bean flour were studied. Phaseolus vulgaris beans of the agronomic cultivar “Flor de mayo” were ground and dehulled to obtain grits and then extruded at different temperatures (140, 160 and 180 °C) and moisture contents (17, 20 and 23%), according to a bifactorial experimental design. Degree of cooking was estimated by water solubility (WS) and specific mechanical energy (SME). The effect of variables on WS and SME were analysed by surface response methodology. Flour dispersion viscosity and mineral availability (estimated by in vitro dialyzability), were also evaluated on selected samples. Results showed that, within the ranges of the variables used for this study, only the effect of temperature was significant on the degree of cooking. No direct correlation was observed between water solubility and SME, although a maximum value of WS corresponded to a range of SME values of 400–500 J/g was observed. Dispersion viscosity decreases as WS increases, so if high calorie density is desired, for instance in order to produce a cream soup formula, bean grits should be extruded at high temperature and as low moisture as possible, in our case 180 °C and 17% moisture. On the other hand, the effects of extrusion variables on iron and zinc dialyzability were not much affected.  相似文献   

5.
《Field Crops Research》2004,85(2-3):203-211
Common bean (Phaseolus vulgaris L.) is an important food crop grown under rainfed conditions in Latin America where drought is a major limiting factor for production. The objective of this study was to assess the role of phenological adjustment and shoot biomass distribution on seed yield of drought-stressed common bean. Four cultivars differing in growth habit, gene pool origin, and contrasting responses under drought, were tested during 2001 at two locations in Mexico: Cotaxtla, Veracruz (lowlands) where the effect of terminal drought (TD) (end-of-season) was evaluated, and Texcoco, State of Mexico (highlands), where the effects of intermittent and terminal drought were evaluated. Seed yield, plant shoot biomass, and days to flowering and to physiological maturity were recorded. Leaf relative water content (RWC) was recorded after the onset of the intermittent drought (ID) treatment in Texcoco. The drought intensity index was 0.37 in Cotaxtla compared to 0.49 and 0.58 under TD and ID, respectively in Texcoco. Days to flowering and to physiological maturity showed a negative and significant relationship with seed yield. Under drought stress, a significant reduction in the harvest index was observed in susceptible cultivars. All cultivars showed higher values of shoot biomass accumulation, pod and seed number, seed weight and RWC at the basal nodes of the plant across locations and moisture treatments. Cultivar Pinto Villa exhibited the highest biomass accumulation and seed yield across treatments and locations. Significant reduction in number of days to maturity was observed under drought, mainly in resistant cultivars, Pinto Villa and G4523. Maturity acceleration, coupled with a high seed filling rate, contributed to lessen the impact of drought stress in resistant common bean cultivars.  相似文献   

6.
Extrusion processing characteristics of Cherry Vanilla quinoa flour (Chenopodium quinoa Willd) were investigated using a three factor response surface design to assess the impact of feed moisture, temperature, and screw speed on the physicochemical properties of quinoa extrudates. Specific mechanical energy (SME) required to extrude this quinoa variety was higher (250–500 kJ/kg) than previously reported for quinoa. The following characteristics of the extrudates were observed: expansion ratio (1.17–1.55 g/cm3), unit density (0.45–1.02 g/cm3), water absorption index (WAI) (2.33–3.05 g/g), and water solubility index (WSI) (14.5–15.87%). This quinoa flour had relatively low direct expansion compared to cereal grains such as corn or wheat, suggesting that it is not well suited for the making of direct expanded products. The study further suggests that there is a need to understand the processing characteristics of new quinoa varieties for cultivation. Understanding extrusion and other quality traits in advance will help to select the appropriate varieties that would allow food processors to meet consumer needs.  相似文献   

7.
The requirements that must be met by bean common mosaic virus (BCMV)-resistant cultivars of the common bean in Zimbabwe, and the feasibility of developing such cultivars, were investigated by a survey among farmers, evaluation of resistant and locally adapted inbred genotypes, and backcrossing to transfer the bc-3 resistance gene to the genetic background of the locally adapted genotypes. Genotypes were evaluated by field trials in a range of environments, by consumer assessment and by measurement of seed size, water absorption capacity (WAC) and cooking time. Backcross generations were evaluated in the field and by measurement of the same seed characters.

Most farmers produced beans in monoculture, using bush or semi-climbing cultivars and a single seed type, the most common colour type being cream with red mottles. This is in strong contrast to the production system in many parts of eastern and central Africa, where intercropping, climbing types and seed-type mixtures are common. The BCMV-resistant genotypes had a similar range of flowering dates, maturity dates and canopy heights to locally adapted genotypes, and a similar range of environmental responses with respect to these variables, but were generally small-seeded. Consumers preferred large seeds, and seed colours that were not generally found in the resistant genotypes. However, the bc-3 gene was readily combined with large seed by backcrossing. The resistant genotypes generally had shorter cooking times than the locally adapted genotypes.

It is concluded that it will not be difficult to combine BCMV resistance with the other characteristics required of bean cultivars in Zimbabwe, with the possible exception of seed colour, and that the same is probably true for other production regions in southern Africa.  相似文献   


8.
Common beans are rich in phenolic compounds, which can provide health benefits to the consumer. The objective of this work was to study the relationship among antimutagenicity, antioxidant and enzymatic activities of methanolic extract and trolox by principal components multivariate analysis. Antimutagenicity of phenolic compounds present in methanolic extract from the seed coat of common beans (P. vulgaris, Flor de Mayo Bajío cultivar) and trolox against AFB1 mutagenicity were evaluated in the Salmonella typhimurium microsuspension assay. Antioxidant capacity of methanolic extract and trolox were evaluated using β-carotene and 1,1-diphenyl-2-picryhydrazyl (DPPH) in vitro model assays. Cythrome P450 activity was measured by fluorometric assay. For phenolic extract, trolox and phenolic extract + trolox, the inhibition on AFB1 mutagenicity in tester strain TA100 was 47, 59 and 69%, respectively. While in TA98 was 39, 48 and 68%. The inhibition of phenolic compounds, trolox and phenolic compounds + trolox on cytochrome P450 (CYP450) activity was 48, 59 and 88%, respectively. Correlation analysis showed that phenolic extract and trolox have high antimutagenic and antioxidant activity and also inhibited enzymatic activity. The results suggest that the primary mechanism of action of phenolic compounds in beans against AFB1 mutagenicity may be extra-cellular in the microsuspension assay.  相似文献   

9.
干旱胁迫对大麦幼苗根系的影响   总被引：1，自引：0，他引：1  
为了解干旱胁迫对大麦幼苗根系生长的影响,采用盆栽称重控制土壤含水量的方法,测定了土壤含水量为田间持水量的85%、55%、45%和35%等4个处理下, 4个抗旱性不同的大麦品种的幼苗根系形态和根系吸收能力等相关指标。结果表明,随着土壤含水量的减少,大麦幼苗的最长种子根、根尖数、根组织含水量均呈下降趋势;根分支数和根冠比总体呈上升趋势;根鞘大小和根毛密度整体上呈先上升后下降的趋势;根系活力与根总吸收面积和根活性吸收面积之间存在一定的互补效应。抗旱性较强的大麦品种较抗旱性较弱的品种,在干旱胁迫下能够保持更庞大的根系、更大的根-土交互面和更高的根系吸收能力。幼苗根系形态可以作为大麦耐旱性的筛选指标。  相似文献   

10.
This study compared the levels of antinutritional components and cytotoxic effect of extracts, from tepary (Phaseolus acutifolius) and common (Phaseolus vulgaris) beans. Antinutritional factors were evaluated by determining their effect on the viability of epithelial cells isolated from rat small intestine. The protein and carbohydrates content were similar in all the genotypes studied (20 and 60%, respectively). Common beans presented higher content of trypsin inhibitors, tannins and lectins than tepary beans. There was not a significant correlation between tannins and cooking time. However, water absorption and cooking time correlated significantly (p < 0.05). Considerable variation was observed in lectin activity (1302–18161 Ul/mg) of extracts from different beans. Tannins, lectins, trypsin inhibitors and fat content differed between bean varieties whereas protein content was similar. The percent cellularity on rat epithelial cells was significantly different among protein extracts from different bean cultivars and ranged between 53.5% and 87.4% (p < 0.05). These results suggest that the incorporation of tepary beans in the diet would not alter the current nutritional contribution of common beans or introduce adverse toxic effects. The agronomic characteristics of tepary beans make them attractive for cultivation. However, the harder to cook phenomenon may be a limiting factor that needs further consideration.  相似文献   

11.
Extruded wheat flours, due to their increased water absorption capacity, constitute an opportunity to increase bread output in bakery production. However extrusion may modify dough and bread characteristics. The aim of this study was to investigate the effect of the substitution of 5% of the wheat flour by extruded wheat flour (produced with different time-temperature extrusion treatments) on dough mixing, handling and fermentation behaviour and bread volume, shape, texture and colour. The RVA curves indicate that extrusion intensity increases with increasing temperature or water content. Water absorption capacity rises with increasing treatment intensity, but dough stability tends to decrease. Adding extruded flours decreases dough extensibility but increases tenacity and gas production. Differences in dough structure were observed on photomicrography, though there were no clear differences in bread quality. These results indicate that it is possible to obtain adequate dough and bread characteristics using dough with 5% extruded wheat flour.  相似文献   

12.
The characteristic of proteins, starch and pectic substances in cotyledons of two bean cultivars varying in cooking time were determined to investigate their possible contribution to bean cooking quality. Both cultivars showed the same enthalpies of starch gelatinization but different protein denaturation enthalpies. The proportion of hot water soluble pectins was higher in Michigan, the cultivar with the lower cooking time, than in Ojo de Cabra, the cultivar with the higher cooking time. These results were not due to differences in pectin methylation or in the ratio of monovalent to divalent cations in the tissue, suggesting that in fresh beans the β-elimination reaction is not the sole or predominant route of thermal pectin degradation. Overall, this study indicates that varietal differences in bean cooking quality may be reflections of the rate of pectin loss during soaking/heating and that the thermal properties of starch and protein fractions seem to have a minor contribution. Researchers involved in this study propose that in fresh beans, the thermal pectin loss results from a two step mechanism: pectin enzymic breakdown during the bean soaking followed by thermal solubilization rather than β-elimination during the bean heating.  相似文献   

13.
Flour from long-grain, high-amylose, milled rice was extruded in a double screw extruder. Response surface methodology (RSM) using a face-centered cube design was used to evaluate the effects of operating variables, namely the screw speed (200–300 rpm), barrel temperature (100–160 °C), and feed moisture content (16–22%) on some functional, physical, pasting, and digestibility characteristics of the extrudates. Regression analyses showed that water absorption index (WAI) was significantly (P<0.05) affected by all linear, quadratic, and interaction terms. Viscosity values of extruded rice flours were far less than those of their corresponding unprocessed rice flour dispersed in the Micro Visco Amylo Graph (MVAG) indicating that the starches had been partially pregelatinized by extrusion process. Peak viscosity indicated a high positive correlation with hot paste viscosity (HPV) and cold paste viscosity (CPV) with r>0.700 (P<0.01). The effects of processing on the in vitro digestibility of starch fractions in rice extrudates was tested using controlled enzymatic hydrolysis with alpha-amylase and glucoamylase. The starch-digestion rate depended mainly on processing conditions. Rapidly digestible starch (RDS) was found to correlate negatively with slowly digestible starch (SDS) (r=−0.964, P<0.01) and with resistant starch (RS) (r=0.793, P<0.01), respectively. Whereas SDS correlated positively with RS (r=0.712, P<0.01).  相似文献   

14.
The objective of the present work is to compare some different crop products such as protein isolates and defatted whole flours from legumes, as chickpea and soy bean, involved in the molded compression processing to obtain plastics. The present work analysed the possibility of forming new plastic materials with products of chickpea, and soy bean seeds typically from the North West of Argentina, conditioned as chickpea isolate (CI), chickpea whole flour (CWF) in relation with soy protein isolate (SI) and soy whole flour (SWF). The blends containing isolates or defatted whole flour of chickpea, with the addition of glucopolysaccharide, glycerol and water as plasticizers were compression molded at 120°C, at 20 MPa, for 7 min. The glucopolysaccharide employed from this vegetals presented a ratio of amylose to amylopectin structure 95/5. The molded specimens were calculated for their tensile strength, percent elongation at break and water absorption. The chickpea isolate would be important in the production of plastic materials because of the best mechanical properties and the smallest water absorption. The chickpea whole flour product gave better material than soy whole flour product, even if the mechanical properties of both are lower than chickpea and soy isolates, respectively. Addition of boric acid in the blend induced a fall in water absorption in the case of soy plastics, but was not important in chickpea plastics. The effect of irradiation was to decrease water absorption in soy plastics and chickpea whole flour, while the effect on mechanical properties was not important.  相似文献   

15.
African breadfruit seeds were cleaned, parboiled (98 °C) for 15min, drained and dehulled. The kernels were sun-dried, then milled andsieved into flour. Nitrogen solubility (NS), water absorption capacity(WAC), emulsion activity (EA), viscosity, foaming and emulsifyingproperties of the flour were determined as functions of pH and NaClconcentration. The NS was pH dependent with a minimum at pH 4 andmaximum at pH 10. The flour also exhibited minimum and maximum foamcapacity at pH 4 and 10, respectively. The minimum emulsion activity wasat pH 4, a value which increased from 7–16% at pH 12. The addition ofNaCl at concentrations of 0.2 to 0.4 M improved WAC, NS, foamingand emulsion properties of the flour. Sodium chloride enhanced NS of theflour at pH 4–6 and EA at pH 2–8.The EA at pH 2, 10 and 12 correlated negatively (r = –0.30) with NaClconcentration levels; however, the correlation was not significant (p> 0.05). The flour dispersions had lower viscosities at acid pH and in thepresence of NaCl than at neutral and alkaline pH values. Results indicatedthe flour could be used in food product supplementation.  相似文献   

16.
Sesame seeds were boiled and allowed to sprout under ambient condition (30±2 °C) with an objective to reduce or eliminate the bitter taste associated with them. The untreated seeds were used as a control. The proximate composition, functional and organoleptic properties of defatted sesame flour were assessed at room temperature. There was a slight increase (about 10%) in protein content of sprouted seeds. The foaming capacity of flours from untreated, sprouted and boiled seeds were 34.6, 38.5 and 11.5%, respectively. The flour from the boiled seeds had the highest foam stability. Flours from untreated or sprouted seeds, gelation started at the least concentration of 6% whereas that from boiled seed was 11%. The emulsion capacity of flours from the untreated or sprouted seeds was the same (27.6 g oil/g sample) while that from boiled seeds was 12.9 g oil/g sample. Emulsion stability with prolonged storage appeared to be more with flours from the sprouted or boiled seeds than that from the untreated ones. The water absorption properties of flours from the untreated, sprouted and boiled seeds were 8.0, 5.9 and 6.5 g H2O/g sample, respectively whereas the oil absorption capacity same (5.9 g oil/g sample). The bitter taste in flours from the untreated or sprouted was high. The bitter taste was not detected in flour from boiled seeds and the functional properties of the flour were not deleteriously affected except foaming and emulsion capacity. Therefore, this boiling method of debittering sesame seed could be practised. The quality of sesame flour obtained with this boiling method could still serve its role in traditional dishes and in the formulation of some other conventional food products.  相似文献   

17.
Whole grain oat flour was extruded under different moisture contents (15%, 18%, 21%), barrel temperatures (100 °C, 130 °C), and screw speeds (160 rpm, 300 rpm, 450 rpm), and selected physicochemical properties, in vitro starch digestibility, and β-glucan extractability of the extrudates were analyzed. An increase in screw speed resulted in an increase in radial expansion index, water absorption index, and water solubility index. Screw speed significantly affected slowly and rapidly digestible starch. Moderate screw speed (300 rpm) led to higher slowly digestible starch with an accompanying decrease in rapidly digestible starch. Low moisture conditions (15%) resulted in the highest resistant starch and water-extractable β-glucan. Under the conditions used in this study, extrusion did not result in changes in water-extractable β-glucan molecular weight. Thus, extrusion might be beneficial in improving functionality and consumer acceptability by affecting physicochemical properties, in vitro starch digestibility, and β-glucan extractability of oat extrudates.  相似文献   

18.
A wheat×maize induced doubled haploid population that segregates at the Awned locus for awned and awnless phenotypes were studied at two field sites using a genetic linkage map. Interval QTL analysis indicated that significant QTLs for wheat flour water absorption and protein content were located on a linkage group associated with the morphological marker, awns. The QTL peak for flour water absorption was located at the Awned locus (B1, 5AL), whilst the QTL peak for protein content was located nearby, 10.1 cm away from the Awned locus. The locations of those QTL were confirmed by analysing data from two independent field trials conducted under different environment conditions. The QTL identified for water absorption controlled 12% and 11% of the observed variance at the two field trials, whilst for flour protein content the QTL explained 7% and 19% of the variance respectively. Variance component analysis indicated that the QTL for water absorption controlled approximately 14.8–25.0% and 13.6–23% of the genetic variance at the two sites studied (Roma and Jimbour) whilst the QTL for protein content explained between 12.8% and 30.4% of the genetic variance at Roma and 34.7–82.6% at Jimbour. Cross-site analysis with composite interval mapping approach resulted in significant LOD values of 6.12 and 9.94 for water absorption and protein content, respectively. The QTL for water absorption was independent from the hardness locus.  相似文献   

19.
Three promising new improved lines of lima beans (Tpl 1B, Tpl 7A and Tpl 175A) were evaluated for physicochemical properties and cooking quality. The beans varied in seed dimensions and weights with Tpl 1B and Tpl 7A having smaller seed volume than Tpl 175A. Seed coat percentages, leached solids and swelling capacities were within a range of 10.2–19.6% (w/w), 0.44–0.92 g/100 g and 94.0–121.0 g/100 g dry bean, respectively. Cooking times varied between 62 and 81 min without soaking and were reduced by about 34%following a presoaking treatment in water for 12 h at room temperature (28 ± 1 °C). Small seeds absorbed higher amounts of water during soaking and required more cooking time than larger seeds. No significant (p>0.05) difference in cooked texture was found between unsoaked beans cooked for 50 min and soaked beans cooked for 30 min,suggesting that cooking times and cooked texture for all lines were improved through soaking.  相似文献   

20.
Pinto beans were milled and then air-classified to obtain a raw high protein fraction (RHPF) followed by extrusion to texturize the protein fraction. The texturized high protein fraction (THPF) was then milled to obtain flour, and combined with wheat flour at 5, 10, and 15 % levels to make bread. The air-classification process produced flour with high concentration of lipids and phytic acid in the protein-rich fraction. However, extrusion significantly reduced hexane extractable lipid and phytic acid. However, the reduction observed may simply indicate a reduction in recovery due to bind with other components. Total protein and lysine contents in composite flours increased significantly as THPF levels increased in composite flour. Bread made with 5 % THPF had 48 % more lysine than the 100 % wheat flour (control). The THPF helped to maintain dough strength by reducing mixing tolerance index (MTI), maintaining dough stability and increasing departure time on Farinograph. Bread loaf volume was significantly reduced above 5 % THPF addition. THPF increased water absorption causing an increase in bread weights by up to 6 %. Overall, loaf quality deteriorated at 10 and 15 % THPF levels while bread with 5 % THPF was not significantly different from the control. These results support the addition of 5 % THPF as a means to enhance lysine content of white pan bread.  相似文献   

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