Effect of storage of adzuki bean (Vigna angularis) on starch and protein properties

Differential scanning calorimetry was used to evaluate the effect of storage at 10°C, 20°C and 30°C, and 40% and 65% relative humidity (RH) on adzuki bean starch gelatinisation and protein denaturation temperatures. Storage for 6 months at an elevated storage temperature (30°C) caused increases in the starch gelatinisation onset temperature (T_o) and gelatinisation peak temperature (T_p) for both Bloodwood and Erimo varieties. Storage at 40% RH resulted in higher T_o and T_p values than storage at 65% RH. The T_o of starch from Bloodwood and Erimo beans stored for up to 1.5 months at 10°C and 65% were similar to those of fresh beans.The changes in the salt-soluble protein component were less clear cut than those of the starch. Nonetheless, protein extracted from beans stored at 40% RH exhibited significantly lower T_o and T_p values compared with those stored at 65% RH. This indicates some destabilisation of the protein at the higher RH.These results suggest that detrimental changes occur in starch and, to a lesser extent protein, of adzuki beans stored under unfavourable conditions. On the basis of these results, the best storage conditions to maintain the characteristics of fresh beans are low temperatures (e.g. 10°C) and high RH (e.g. 65%).     

Study on the water state,mobility and textural property of Chinese noodles during boiling

The water mobility, state and textural properties of Chinese fresh noodles (CFNs) and Chinese dried noodles (CDNs) made from same wheat cultivar were measured during boiling using low-field nuclear magnetic resonance (LF-NMR), low-field nuclear magnetic Imaging (LF-NMI) and a textural analyser. ‘The oil immersion method’ was applied to gain the clear images from LF-NMI measurement. The distributions of the three water states (T₂₁, T₂₂ and T₂₃) in the noodles were distinguished. The results indicated that water mobility in noodles was closely related to the gelatinisation of noodle starch. Compared with CFNs, CDNs need a longer cooking time for water mobility and starch gelatinisation. The results of the cooked noodle profiles showed that the cooked CDNs (8 min) had an undesirable textural properties compared with the cooked CFNs (2 min). The longer cooking time of CDNs is responsible for its undesirable texture since the textural properties change during the longer cooking time.     

Changes in flour gelatinisation of trifoliate yam (Dioscorea dumetorum) tubers after harvest

BACKGROUND: Changes in the properties of starch during postharvest hardening of trifoliate yam (Dioscorea dumetorum) tubers need to be investigated. In this work the starch gelatinisation kinetics of D. dumetorum cv. Yellow stored under prevailing tropical ambient conditions (0.98–2.32 kg vapour per 100 m³ airflow) for 0, 2, 7, 14, 21 and 28 days was studied using a 3 × 5 factorial experiment with three cooking temperature (75, 85 and 95 °C) and five cooking times (0, 5, 10, 20 and 40 min). Samples were also evaluated for starch properties and gelatinisation temperature. RESULTS: Storage of D. dumetorum tubers caused starch damage. However, the starch gelatinisation temperature was between 70 and 75 °C irrespective of the tuber storage duration. The starch gelatinisation reaction followed first‐order kinetics defined by the relationship ln(1 ? α) = ? k_Gt. The gelatinisation rate was significantly influenced (P≤0.05) by cooking temperature and increased with tuber storage duration. The activation energy also increased with tuber storage duration. CONCLUSION: Although the gelatinisation temperature of D. dumetorum starch was not influenced by tuber storage, the starch gelatinisation process was affected by tuber storage duration, since tuber storage involved a greater need of energy for starch gelatinisation, which may be an effect of the postharvest hardening phenomenon. Copyright © 2008 Society of Chemical Industry     

Characteristics and oil absorption in deep‐fat fried batter prepared from ball‐milled wheat flour

BACKGROUND: The porous structure generated during frying influences oil absorption and textural qualities. The alteration in physical properties of wheat flour is suspected to affect the structure formation. The present study investigated the effect of physicochemical changes in wheat flour by the ball‐milling process on structure formation and consequently oil absorption of a fried wheat flour batter model. RESULTS: Batter models containing 600 g kg^?1 moisture were made of 0–10 h ball‐milled wheat flour and then fried in frying oil at 150 °C for 1–7 min. The samples made of milled flour possess larger pores and exhibit lower oil absorption than sample made of 0 h milled flour. The fracture force of a fried sample prepared from 5 and 10 h milled flour is lower than that of a sample prepared from 0 h milled flour. CONCLUSION: The decrease in glass transition temperature (T_g) and melting temperature (T_m) of milled flour affect the microstructure formation in the fried wheat flour batter. The microstructure is responsible for oil absorption and fracturability in fried food. The samples made of flour of longer ball‐milling time have lower oil absorption and higher crispness. Ball‐milling may be a tool to produce mechanically modified wheat flour which can reduce oil absorption for fried batter. Copyright © 2009 Society of Chemical Industry     

Structure and Viscoelastic Properties of Starches Separated from Different Legumes

A comparison between the morphological, structural, thermal and viscoelastic properties of starches separated from pigeon pea, chickpea, field pea, kidney bean and blackgram was made. The shape of the starch granules in the different legumes varied from oval to elliptical or spherical. X-ray diffraction of the legume starches indicated a typical C-pattern (mixture of A- and B-type). Granules of blackgram and pigeon pea starch had a higher degree of crystallinity than those of field pea and kidney bean starches. Apparent amylose content of field pea, kidney bean, chickpea, blackgram and pigeon pea starch was 37.9%, 36.0%, 34.4-35.5%, 32.9-35.6% and 31.8%, respectively. Distribution of isoamylase-branched materials among the starches revealed that the proportions of long and short side chains of amylopectin ranged between 13.6-18.5% and 41.7-46.5%, respectively. Field pea and kidney bean starch had the highest apparent amylose content and the lowest amount of long side chains of amylopectin, respectively. Blackgram and pigeon pea starch possessed higher proportions of both long and short side chains of amylopectin than field pea and chickpea starches. The onset, peak and conclusion temperatures of gelatinization (T_o T_p and T_c, respectively) were determined by differential scanning calorimetry. T_o and T_c ranged from 59.3 to 77.3°C, 66.8 to 79.6°C, 55.4 to 67.6°C and 68.3 to 69.3°C, respectively, for chickpea, blackgram, field pea and kidney bean starch. The enthalpy of gelatinization (ΔH_gel) of field pea, kidney bean, chickpea, blackgram and pigeon pea starches was 3.6, 3.0, 2.6-4.2, 1.6-1.7 and 2.6 J/g, respectively. Pastes of blackgram and pigeon pea starches showed lower storage and loss shear moduli G′ than field pea, kidney bean and chickpea starches. The changes in moduli during 10 h at 10°C revealed retrogradation in the order of: field pea> kidney bean> chickpea> blackgram> pigeon pea starch. In blackgram and pigeon pea starches, the lower proportion of amylose plus intermediate fraction and higher proportion of short and long side chains of amylopectin are considered responsible for the higher crystallinity, gelatinization temperature and enthalpy of gelatinization.     

Effects of frying temperature,pressure and time on gelatinisation of sago flour as compared to wheat and rice flour in fried coating

This study was conducted to determine the gelatinisation properties of coating with sago flour compared with wheat and rice as influenced by frying temperature, pressure and time. Chicken nuggets were immersed in sago, rice or wheat flour batters and fried at temperatures of 150, 165 and 180 °C and under pressures of 102 and 156 kPa for 0, 6, 18 and 30 s. Results showed that T_o of coatings from sago flour ranged from 71.8 to 74.7 °C. T_o of coatings from wheat flour ranged from 58.2 to 61.2 °C, while that of coatings from rice flour ranged from 77.9 to 78.6 °C. Except for a few combinations, frying temperature and pressure used did not have any significant effects on onset (T_o), peak (T_p) and end (T_e) temperatures. Except for a few combinations, degree of gelatinisation of coatings from sago flour was not influenced by frying temperature and pressure similar to coatings from rice and wheat flour.     

Molecular and physicochemical characterisation of starches from yam,cocoyam, cassava,sweet potato and ginger produced in the Ivory Coast

Granule sizes, macromolecular features and thermal and pasting properties of starches from seven tropical sources (Florido, Kponan and Esculenta yams, cocoyam, cassava, sweet potato and ginger) were compared with those of several well‐known cereal, legume and tuber starches. The aim of the study was to characterise some non‐conventional starches with a view to possibly marketing them. Amylose content varied from 148 mg g^?1 in Esculenta starch to 354 mg g^?1 in smooth pea starch. For total starches, weight‐average molar mass (M?_w) ranged between 0.94 × 10⁸ and 1.80 × 10⁸ g mol^?1 for potato and normal maize starches respectively. Gyration radius (R?_G) varied from 157 nm for ginger starch to 209 nm for normal maize starch. Gelatinisation enthalpy (ΔH) ranged between 9.8 and 20.7 J g^?1 for wheat and Florido starches respectively. Gelatinisation peak temperature (T_g) varied from 58.1 °C for wheat starch to 87.3 °C for ginger starch. Native starch granule mean diameter ranged between 5.1 and 44.5 µm for Esculenta and potato starches respectively. Cassava and potato starches had the highest swelling power and dispersed volume fraction at all treatment temperatures, while ginger starch had the lowest. Cocoyam starch had the highest and ginger starch the lowest solubility at 85 and 95 °C. Cassava starch was the most stable under cold storage conditions. Roots and tubers such as ginger and cassava produced in the Ivory Coast are new sources of starches with very interesting properties. Thus these starches could be isolated on an industrial level in order to market them. Copyright © 2007 Society of Chemical Industry     

Physico‐Chemical and Structural Characteristics of Vegetables Cooked Under Sous‐Vide,Cook‐Vide,and Conventional Boiling

In this paper, physico‐chemical and structural properties of cut and cooked purple‐flesh potato, green bean pods, and carrots have been studied. Three different cooking methods have been applied: traditional cooking (boiling water at 100 °C), cook‐vide (at 80 and 90 °C) and sous‐vide (at 80 °C and 90 °C). Similar firmness was obtained in potato applying the same cooking time using traditional cooking (100 °C), and cook‐vide and sous‐vide at 90 °C, while in green beans and carrots the application of the sous‐vide (90 °C) required longer cooking times than cook‐vide (90 °C) and traditional cooking (100 °C). Losses in anthocyanins (for purple‐flesh potatoes) and ascorbic acid (for green beans) were higher applying traditional cooking. β‐Carotene extraction increased in carrots with traditional cooking and cook‐vide (P < 0.05). Cryo‐SEM micrographs suggested higher swelling pressure of starch in potatoes cells cooked in contact with water, such as traditional cooking and cook‐vide. Traditional cooking was the most aggressive treatment in green beans because the secondary walls were reduced compared with sous‐vide and cook‐vide. Sous‐vide preserved organelles in the carrot cells, which could explain the lower extraction of β‐carotene compared with cook‐vide and traditional cooking. Sous‐vide cooking of purple‐flesh potato is recommended to maintain its high anthocyanin content. Traditional boiling could be recommended for carrots because increase β‐carotenes availability. For green beans, cook‐vide, and sous‐vide provided products with higher ascorbic acid content.     

Properties of Starch Separated From Ten Mung Bean Varieties and Seeds Processing Characteristics

Starch samples from ten mung bean cultivars grown in china were isolated, and their morphology, physicochemical, thermal, and pasting properties were evaluated. The objectives of the study were to investigate the starch properties and processing characteristics of different mung bean varieties, and to establish the basic foundation of improving the functionality of mung beans and their starch grown in the region. The mung bean starches showed the kidney-shaped, elliptical, small spherical and dome-shaped granules, and the starches granule size varied between 5 and 40 μm. Total starch content, amylose content, solubility, and swelling power ranged from 54.73% to 57.99%, 40.44% to 41.82%, 13.72% to 17.67%, and 17.27% to 20.55%, respectively. The pasting properties were determined using a rapid visco analyzer, and various mung bean starches exhibited different pasting profiles. Different starches differed in transition temperatures (T _o, T _p, and T _c), gelatinization temperature range (ΔT _r), and enthalpy of gelatinization (ΔH) according to differential scanning calorimeter analysis. Hydration coefficient, degree of gelatinization, and hardness of mung bean varieties ranged from 51.97% to 84.46%, 62.99% to 95.11%, and 26.07 N to 112.11 N, respectively. This study indicated that starches separated from different mung bean cultivars possess different physicochemical characteristics, and various mung beans cultivars showed diverse processing properties.     

Studies on bambara groundnut flour performance in Okpa preparation

Bambara groundnut flours of different particle sizes were prepared after bean seeds had been cold‐soaked and/or germinated, dried, milled and sieved. The flours were used to prepare okpa (local dish prepared by steaming mashed bambara groundnut) and their sensory properties determined. Viscosity of the flour pastes, before steaming, were also determined. Results showed that bambara groundnut flours from both germinated and cold‐soaked beans could be used in preparing good quality okpa and, therefore, remove all the problems involved in preparing the raw beans for okpa‐making as is done traditionally. Particle size appeared to play a major role in obtaining good okpa; therefore flours intended for okpa preparation should be such that 66, 86 and 96%, respectively, of cold‐soaked bean flour or 58, 78 and 91%, respectively, of germinated bean flour, after 1, 3 and 5 milling passes, should be in the particle range 1.5–4.5 × 10^?4 m. Slightly higher amounts of the coarse (6.0 × 10^?4 m) particles are needed in the germinated bean flours to compensate for the breakdown of starch and proteins, the gelling agents in bambara groundnut. Copyright © 2004 Society of Chemical Industry     

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     

Relating consumer preferences to sensory and physicochemical properties of dry beans (Phaseolus vulgaris)

BACKGROUND: Dry beans (Phaseolus vulgaris) have a range of varieties, colours and sizes. Differences in physicochemical and sensory properties influence consumer choices for beans. This study related consumer preferences to sensory and physico‐chemical properties of selected bean varieties—Jenny, Kranskop, PAN 148, AC Calmont, PAN 150 and Mkuzi—grown in Mpumalanga (MP) and Free State (FS) in South Africa. RESULTS: Significant (P < 0.05) variety, location as well as location × variety interaction effects were found for both physico‐chemical and sensory properties of beans. Jenny‐FS, Mkuzi and PAN 148‐MP beans had relatively long cooking times (>60 min). Some beans (e.g. PAN 150 and Mkuzi beans) were described as bitter, soapy and metallic with a raw‐bean flavour whereas more preferred beans (e.g. Jenny‐MP, Kranskop‐MP) were sweet, soft and with a cooked‐bean flavour. CONCLUSION Apart from small seed size, sensory characteristics such as bitter taste, soapy and metallic mouthfeel and hard texture contributed to consumers' dislike of certain bean varieties. The sweet taste, cooked‐bean flavours, soft and mushy textures of the most accepted varieties seemed to be related to beans with good hydration capacities that facilitated softening during cooking. Copyright © 2007 Society of Chemical Industry     

Functional properties and retrogradation behaviour of native and chemically modified starch of mucuna bean (Mucuna pruriens)

Mucuna bean (Mucuna pruriens) starch was isolated and subjected to chemical modification by oxidation and acetylation. The proximate analysis of the non‐starch components of the native starch on a dry weight basis was 92 g kg^?1 moisture, 5 g kg^?1 ash, 2 g kg^?1 fat, 7 g kg^?1 crude fibre and 19 g kg^?1 protein. Chemical modification reduced the values for all the non‐starch components except the moisture level. For all the samples, swelling power and solubility increased as the temperature increased in the range 50–90 °C. The swelling power of mucuna native starch (MNS) and mucuna acetylated starch (MAS) increased with increasing acidity and alkalinity, while that of mucuna oxidised starch (MOS) only increased with increasing pH in the acidic range. The maximal solubility of all the starches was observed at pH 12. All the starch samples absorbed more oil than water. The lowest gelation concentration followed the trend MAS < MNS < MOS. Chemical modification reduced the gelatinisation temperature (Tp), while peak viscosity (Pv), hot paste viscosity (Hv) and cold paste viscosity (Cv) decreased after oxidation but increased following acetylation. The setback tendency of the native starch was reduced significantly after chemical modification. However, the breakdown value of MNS, 65 BU (Brabender units), was lower than that of MOS (78 BU) but higher than that of MAS (40 BU). Differential scanning calorimetry studies of gelatinisation and retrogradation revealed that chemical modification reduced the onset temperature (T_o), peak temperature (T_p) and conclusion temperature (T_c). Oxidation and acetylation reduced the gelatinisation and retrogradation enthalpies of the native starch. The enthalpy of retrogradation of the starches increased as the length of storage increased. Copyright © 2003 Society of Chemical Industry     

Microstructures of starch granule,starch digestibilities and predicted glycaemic index of common bean mutants in Taiwan

In this study, the microstructure of starch granule and in vitro starch digestibility were compared in de‐coated seeds of common bean variety Hwachia and its NaN₃‐induced mutants. Significant differences in starch granule size (between 17.92 and 27.00 μm), total starch content (between 436.5 and 456.8 mg per seed) and resistant starch content (between 51.6 and 203.3 mg per seed) were found among mutants. Both boiling and autoclaving decreased resistant starch content in processed common beans. Significant difference in predicted gylcaemic index (pGI) (between 48.82 and 64.55%) for processed beans also existed among mutants. However, 96 h of 4 °C storage increased resistant starch content in processed common beans, possibly resulted from starch retrogradation during storage. Mutants SA‐05, SA‐08 and SA‐31, which have smaller seed weight and lower pGI (average of 50.08%) compared to Hwachia (pGI of 57.05%), can be used to produce common bean based low GI dietary carbohydrate.     

Thermal processing of rice grains affects the physical properties of their pregelatinised rice flours

Waxy, low- and high-amylose rice were cooked at different temperatures (50, 70, 90 °C) for different times (15, 30, 45 min). The microscopic, rheological and gel textural properties of resultant flours were investigated. There was a coarser and discontinuous honeycomb-like structure with formation of pores in rice flour with greater cooking degree. T_Gʹmax was positively correlated with cooking temperature and time. As cooking temperature increased, the Gʹ values of pastes first increased and then decreased, whereas the opposite trend was observed for tan δ. Meanwhile, increased cooking temperature was responsible for increases in n values and caused drops in K and hysteresis area. As cooking time increased, the hardness and gumminess of gels from rice cooked were increased at lower temperature, but were decreased at higher temperature. Overall, cooking temperature was more important in determining the processing properties of rice flours than cooking time.     

Measurement of electrical conductivity,differential scanning calorimetry and viscosity of starch and flour suspensions during gelatinisation process

Electrical conductivity measurements were applied to analyse the gelatinisation process of 12 starch or flour suspensions. The electrical conductivity of starch suspensions was found to increase upon gelatinisation because of the release of ions from starch granules. The initiation temperature of ion release, T_i, correlated well with the onset temperature in the DSC thermogram (R = 0.868), while the completion temperature of ion release, T_f, correlated with the temperature at the start of viscosity increase (R = 0.865). Thus T_i and T_f corresponded to the beginning and ending temperatures of gelatinisation respectively. The electrical conductivity measurement will be used as an on‐line technique to monitor the whole process of starch gelatinisation. © 2001 Society of Chemical Industry     

Effect of the Addition of Common Bean (Phaseolus vulgaris L.) Flour on the In Vitro Digestibility of Starch and Undigestible Carbohydrates in Spaghetti

Abstract: Spaghetti is considered to be a slowly digestible starch food, a feature ruled by the particular physical properties of the product. Several studies have been reported to increase nutritional value of spaghetti, using legumes. We have studied the addition of common bean flour on the starch in vitro digestibility. Spaghetti was prepared with semolina and different concentrations of common bean flour (0%, 15%, 30%, and 45%, w/w). Proximate analysis, optimal cooking time, and cooking loss were estimated in crude spaghetti. Total, available, and resistant starches, indigestible fractions, and in vitro starch hydrolysis kinetics were accomplished in cooked spaghetti. Pasta with 30% and 45% of common bean flour showed higher values of protein. Particularly, the lowest cooking time was observed for composite spaghetti with 45% of common bean flour. There was a significant increase in cooking loss when common bean flour in the composite was added. Composite spaghetti samples with increasing common bean flour showed decreasing values of total starch but an important increase in the resistant starch (RS) level and indigestible insoluble fraction values. Plain pasta made with semolina showed the highest enzymatic hydrolysis rate, which decreased when common bean flour was added to the spaghetti. Spaghetti with a higher level of common bean flour was more slowly available, which may have positive implications for human health.     

Resistant starch and thermal,morphological and textural properties of heat‐moisture treated rice starches with high‐, medium‐ and low‐amylose content

This study investigated the effects of heat‐moisture treatment (HMT) on the resistant starch content and thermal, morphological, and textural properties of rice starches with high‐, medium‐ and low‐amylose content. The starches were adjusted to 15, 20 and 25% moisture levels and heated at 110°C for 1 h. The HMT increased the resistant starch content in all of the rice starches. HMT increased the onset temperature and the gelatinisation temperature range (T_finish–T_onset) and decreased the enthalpy of gelatinisation of rice starches with different amylose contents. This reduction increased with the increase in the moisture content of HMT. The morphology of rice starch granules was altered with the HMT; the granules presented more agglomerated surface. The HMT affected the textural parameters of rice starches; the high‐ and low‐amylose rice starches subjected to 15 and 20% HMT possessed higher gel hardness.     

Gelatinization Characteristics of Starch from du,wx, ae,and ae wx Endosperm of Sweet Corn Inbred la5125

Starch gelatinization in excess water was studied by differential scanning calorimetry for the mutants dull (du), waxy (wx), and amylose extender (ae), and the double mutant amylose-extender, waxy (ae wx) from the Ia5125 sweet corn inbred background. Onset temperature (T_o), peak temperature (T_max), and enthalpy (ΔH) were determined. For du and wx starches T_max was within 1°C of the value for the normal starch (T_max = 69.4°C). For starches from ae and ae wx mutants, T_max was 7–8°C higher than the normal starch. The highest enthalpies were observed for wx (3.26 cal/g) and ae wx (3.39 cal/g) starches; ae (2.93 cal/g) and normal (2.52 cal/g) starches were intermediate, and du (2.32 cal/g) starch had the lowest enthalpy. The endotherm of the ae starch was completed at just above 100°C, in distinction to reports for ae mutants from dent lines. Although the ae wx endotherm occurred at a higher temperature than the wx, the endotherm was sharpened relative to the ae endotherm, and was complete at 90°C.     

Protein Denaturation and Starch Gelatinization in Hard-To-Cook Beans

A study was undertaken to assess protein denaturation and starch gelatinization in ground samples of common black beans exhibiting the hard-to-cook (HTC) defect. Using differential scanning calorimetry, no significant differences in either gelatinization or denaturation temperatures were found between hard and soft beans but tropical storage conditions produced significant increases in gelatinization enthalpy and decreases in denaturation enthalpy. Endotherms of cooked samples showed as little as 34% of the protein had denatured in HTC beans as compared to over 85% in soft beans. Micrographs indicated the ground raw material was composed of clumps of cotyledon cells; cooking soft beans produced cell separation but this did not occur in HTC samples. These data supported the idea that bean hardening was accompanied by limited water availability inside cotyledon cells that could reduce cell swelling, starch gelatinization and protein denaturation, leading to textural toughness.