Physico-chemical and morphological characteristics of New Zealand Taewa (Maori potato) starches

Effect of addition of processed bambara nut on the functional and sensory acceptability of millet-based infant formula

Fermentation and sprouting have been shown to increase nutrient bioavailability and modify the functional properties of foods. Application of these methods in the preparation of infant foods and complementing cereals with legumes will address nutrient density and viscosity problems associated with infant foods. Infant foods were formulated from blends of treated bambara nut and pearl millet. Functional properties, pasting properties, and sensory acceptability of the blends were studied. Millet and bambara nut were soaked separately in water and allowed to ferment for 48 hr at room temperature. While for sprouting, millet and bambara nut were soaked for 12 and 24 hr, respectively, at room temperature, and soaked seeds were separately sprouted for 48 hr. After fermentation and sprouting, the seeds were oven-dried and then milled into a flour of 0.6 mm size. The flours were formulated to six (A, B, C, D, E, and F) complementary diets. The results show that sample E had the suitable water absorption capacity, while, for oil absorption capacity, various blends showed suitability except samples A and B. In terms of swelling capacity, sample F (6.52 ± 0.01%) was the suitable at 60°C. Treatment and blending significantly influenced trough, final viscosity, and pasting time. In sensory acceptability, sample B was adjudged the best. This study revealed that sample C was the best in respect to functional and pasting properties for infant food; however, sample B received the best general acceptability.

Modified Dioscorea hispida starch-based hydrogels and their in-vitro cytotoxicity study on small intestine cell line (FHS-74 Int)

Starch-based hydrogels are promising smart materials for biomedical and pharmaceutical applications, which offer exciting perspectives in biophysical research at molecular level. This work was intended to develop, characterize and explore the properties of hydrogel from starch extracted from new source, Dioscorea hispida Dennst. Starch-mediated hydrogels were successfully synthesized via free radical polymerization method with varying concentrations of acrylic acid (AA),N,N'-methylenebisacrylamide (MBA) and sodium hydroxide (NaOH) in aqueous system. The grafting reaction between starch and AA was examined by observing the decline in intensity peak of hydrogel FTIR spectrum at 3291cm^-1 and peak around 1600-1680cm^-1, indicating the stretching of hydroxyl group (OH) and stretching of carbon-carbon double bond (CC) respectively. The effects of cross-linker, monomer and NaOH concentration on swelling ratio and gel content in different medium and conditions were also evaluated. The thermal stability and structural morphology of as-synthesized hydrogels were studied by thermogravimetry analysis (TGA) and scanning electron microscopy (SEM). In-vitro cytotoxicity study using small intestine cell line (FHS-74 Int) revealed that the as-formulated eco-friendly-hydrogel was free from any harmful material and safe to use for future product development.

Effects of tempering (annealing), acid hydrolysis, low-citric acid substitution on chemical and physicochemical properties of starches of four yam (Dioscorea spp.) cultivars

The effects of tempering (annealing), acid hydrolysis and low-citric acid substitution on chemical and physicochemical properties of starches of four Nigerian yam cultivars were investigated. Crude fat and protein contents of the native starches decreased significantly after the modifications, while nitrogen-free extract increased significantly with acid hydrolysis and citric acid substitution. Acid hydrolysis and low-citric acid substitution reduced the least concentration for gel formation of the starches from 4 to 2% w/v, but tempering had no effect. Swelling power of the starches reduced significantly, and water solubility increased significantly at 75 and 85 °C, especially with acid hydrolysis and low-citric acid substitution. However, tempering significantly reduced starch solubility in the four cultivars. Paste clarity of starches of white (29.17%), water (18.90%), yellow (30.90%) and bitter (10.57%) yams reduced significantly with tempering to 14.43, 11.83, 16.93 and 7.27%, but increased significantly with acid hydrolysis to 41.40, 35.37, 28.77 and 32.33%, and low-citric acid substitution to 36.60, 44.17, 50.67 and 14.33%, respectively. Pasting properties such as peak, trough, breakdown, final, and setback viscosities and peak time of native starches reduced significantly with acid hydrolysis and low-citric acid substitution, however, tempering significantly increased their pasting temperature, peak time, setback and final viscosities.

Effects of salts on the freeze-thaw stability, gel strength and rheological properties of potato starch

The objective of this study was to evaluate the effects of different salts (NaF, NaCl, NaBr, NaI, K2SO4, KCl, KNO3, KSCN, LiCl) on freeze-thaw stability, gel strength and rheological properties of potato starch. Addition of the structure-making (salting-out) ions, such as F- and SO42-, decreased freeze-thaw stability and increased gel strength, maximal storage modulus (G') and maximal loss modulus (G″) of potato starch, due to a stronger three-dimensional network by promoting the starch retrogradation and inhibiting starch gelatinization. Shear stress versus shear rate of all samples at 25 °C was well fitted to the simple power-law model with high determination coefficients (R2 = 0.9863-0.9990). Flow behavior index (n), consistency index (K) and apparent viscosities increased with adding salting-out ions. However, the structure-breaking (salting-in) ions had reverse effects on freeze-thaw stability, gel strength and rheological characteristics of potato starch. The addition of structure-breaking ions, such as Br-, NO3-, I-, SCN-, Na+ and Li+, decreased gel strength, G' and G″ values and increased freeze-thaw stability. Salts could significantly influence on the retrogradation of potato starch, generally following the ion order: F- > SO42- > Cl- > Br- > NO3- > I- > SCN- for anions and K+ > Na+ > Li+ for cations, consistent with the Hofmeister series.

Acetylated starch nanocrystals: Preparation and antitumor drug delivery study

In this study, we developed a new nanoparticulate system for acetylated starch nanocrystals (ASN) using broken rice. ASN with different degrees of substitution (DS) of 0.04, 0.08 and 0.14 were prepared using acetic anhydride as acetylating agent through reaction with starch nanocrystals (SN). The resulting ASN were investigated for the capability to load and release doxorubicin hydrochloride (DOX), and the antitumor activities of DOX-loaded SN and DOX-loaded ASN were evaluated as potential drug delivery systems for cancer therapy. Cellular uptake and cytotoxicity of nanocrystals and the DOX-loaded nanocrystals were investigated using fluorescence microscopy and a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) (MTT) assay. Compared with acetylated starches (AS) and native starches (NS), ASN with DS 0.14 loaded up to 6.07% of DOX with a higher loading efficiency of 91.1% and had steadier drug-release rates. Toxicity analysis using the rat hepatocytes model suggested that ASN was biocompatible and could be used for drug delivery. Furthermore, ASN were taken up by cancer cells in vitro and significantly enhanced the cytotoxicity of DOX against HeLa human cervical carcinoma cells. The IC50 value of DOX-loaded ASN-DS 0.14 was 3.8μg/mL for 24h of treatment, which was significantly lower than that of free DOX (21μg/mL). These results indicate that the prepared ASN using broken rice is a promising vehicle for the controlled delivery of DOX for cancer therapy.

Effects of cross-linking modification with phosphoryl chloride (POCl3) on pysiochemical properties of barley starch

Chemical methods are one of the comon method in starch modification. This study aimed at investigating of cross-link affection of phosphoryl chloride with two different levels 0.5 and 1g.kg-1 in order to enhance funciotnal proeprties and physiochemical changes on extracted starch from barley variety Bahman which cultivates in Chahr-Mahal Bakhtiari Province of Iran. Obtained results indicated that cross-linking leads to reduce sweeling power of strach granuls compred to natural starch and the amount of reduciton increase via the substitituin level. Powerfull cross-linkingnetween starch chains casue more resistance of granules to seweeling which is increased by means of cross-linking dgree. Additioally,  investigationresults from synersis revealed that releasing water percentage in cross-linked starches increase in comparison to natural starches and this amount depends onthe amount of cross-link surface with a significantly difference in (α <0.05). Gelatinization temperature in both levels negligibly increased by modification where in low level of cross-linking was more. Furthermoe evaluating gelation temperatures of both natural and cross-linked modified starches showed that addition of phosphate groups in starch and creating extra coovalent bonds make granues more compressed reulting in slight increase of To, Tp, Tcin barley starch. Icreasing of temperature observed more in less concentration of cross-links. Evaluation of viscosity changes also revealed that this modification depending on increasing the amount of Phosphoryl Chloride led to increasing peak temperature, diminish peak and setback viscosity. Result also exhibited that in morphological level, cross-link causes to incidence changes in particles' diameter size. The comparison of diameter average and frequency between natural starch and cross-links starch exhibited that in cross-linkd treatment with 0.5% phosphoryl chloride, increase in frequency of granules with diameter of 6 - 10µm and >20 µm obersced. While frequency of granules with diamater size of 2 - 6 µm and 10 - 20 µm has been reduced to 0 which create bigger granules.

Physico-chemical properties of acetylated starches from Indian black gram (Phaseolus mungo L.) cultivars

Starches separated from three black gram cultivars were modified by acetylation and compared to their native starches. Acetylation was carried out by treating starches with 0.04 and 0.08 g of acetic anhydride/g of starch dry weight basis (db) at 25 °C. The extent of acetylation increased proportionally with the concentration of acetic anhydride used. Retrogradation of acetylated starch pastes decreased significantly (p ≤ 0.05) as revealed by significant decrease in syneresis, increased freeze thaw stability and increased light transmittance. The pasting curves of 10.7 % starch slurries showed that acetylation decreased the setback viscosity values by 51.2-82.8 % and pasting temperature by 3.1-5.6 °C than respective native starches. Differential scanning calorimetry observations also revealed significant decrease in gelatinisation temperature of acetylated starches than native starches. Hardness and adhesiveness of starch gels varied between 10.3 and 32.6 g and 4.6-82.3gs, respectively which were significantly lower than corresponding native starch gels.

Relationship between structure and functional properties of normal rice starches with different amylose contents

The structures (morphology, molecule, and crystallinity) and functional properties (gelatinization, hydrolysis, and in vitro digestion) of normal rice starches with different amylose contents were investigated and their relationships were analyzed. The results showed that the morphology, granule size, and crystalline type did not significantly change among rice starches. The molecular structure (amylose content, amylopectin branch-chain content, and amylopectin branching degree) and crystalline structure (relative crystallinity, IR ratio of 1045/1022 cm(-1), lamellar peak intensity, and lamellar distance) significantly varied among rice starches, which resulted in different functional properties. The gelatinization temperature and water solubility were significantly positively correlated with amylose content but significantly negatively correlated with amylopectin short branch-chain. The swelling power, hydrolysis and in vitro digestion were significantly positively correlated with amylopectin short branch-chain, relative crystallinity, IR ratio of 1045/1022 cm(-1), and lamellar peak intensity but significantly negatively correlated with amylose content and lamellar distance.

The physical, chemical and functional characterization of starches from Andean tubers: oca (Oxalis tuberosa Molina), olluco (Ullucus tuberosus Caldas) and mashua (Tropaeolum tuberosum Ruiz & Pavón)

The physical, chemical, and functional properties of starches isolated from the Andean tubers oca (Oxalis tuberosa M.), olluco (Ullucus tuberosus C.) and mashua (Tropaeolum tuberosum R. & P.) were studied. The tubers were obtained from a local grocery. The morphology of the starch granules (size and shape) was studied with scanning electron microscopy (SEM), which revealed ellipsoid, oval, conical, pear-shaped and prismatic forms: ellipsoids and oval granules with lengths up to 54.30 µm in oca; with lengths up to 32.09 µm for olluco starch granules; and with predominantly truncated spherical or oval forms and smaller dimensions (up to 16.29 um) for mashua starch granules. Amylose contents were similar among the samples: 27.60% (oca), 26.49% (olluco) and 27.44% (mashua). Olluco starch had less swelling power, forming opaque, less firm gels. All three starch gels showed the same stability on refrigeration and presented high syneresis under freezing temperatures, with a variation of 40.28 to 74.42% for olluco starch. The starches cooked easily, with high peak viscosity. The low gelatinization temperatures and high stability during cooling make these starches suitable feedstock for use in formulations that require milder processing temperatures and dispense freezing storage.

Chemical composition and functional properties of native chestnut starch (Castanea sativa Mill)

Starch isolation methods can change their physico-chemical and functional characteristics hindering the establishment of a starch-food functionality relation. A simple high yield and soft isolation method was applied for chestnut (Castanea sativa Mill) starch consisting in steeping and fruit disintegration in a 25 mM sodium bisulfite solution and purification by sedimentation. Starch integrity, physico-chemical composition, morphology and functional properties were determined, being observed significant differences from previous described methods for chestnut starch isolation. The X-ray pattern was of B-type, with a degree of crystallinity ranging from 51% to 9%, dependent on the starch moisture content. The onset, peak, and conclusion gelatinization temperatures were 57.1°C, 61.9°C and 67.9°C, respectively. Total amylose content was 26.6%, and there was not found any evidence for lipid complexed amylose. Swelling power at 90°C was 19 g/g starch, and the amount of leached amylose was 78% of the total amylose content. Native chestnut starch presents a type B pasting profile similar to corn starch but with a lower gelatinization (56.1°C) and peak viscosity (79.5°C) temperatures, making native chestnut starch a potential technological alternative to corn starch, especially in application where lower processing temperatures are needed.

Isolation and Physicochemical Properties of Hardleaf Oatchestnut (Castanopsis sclerophylla) Starch

Starch from hardleaf oatchestnut was isolated, and its chemical composition and physicochemical properties were determined and compared with those of corn or potato starch. The yield and purity of the starch were 386.5 g kg-1 and 912.6g kg-1, respectively, and the starch granules were in spherical and irregular shape ranging from 8μm to 18μm in diameter. It contained 275.4 g kg-1 amylose and had relatively low gelatinization temperature with 60.38°C, and moderate solubility as well as swelling power. The starch gel showed weak freeze-thaw stability with high syneresis of 20.5%, and high viscosity (667BU), hardness (75.06g) and gumminess (30.68g), therefore, making it potentially useful as thickening agent in sweets processing, baking industry and seasoning, but was not appropriate in frozen foods.

Isolation and physicochemical characterisation of starch from cocoyam (Colocasia esculenta) grown in Malawi

BACKGROUND

The aim of this study was to determine the physicochemical properties of starches isolated from Malawian cocoyams and compare them with those of cassava and corn starches.

RESULTS

The purity of the isolated starches varied from 851 to 947 g kg(-1) and pH from 4.93 to 6.95. Moisture, ash, protein, fat and amylose contents ranged from 104 to 132, 0.3 to 1.5, 3.5 to 8.4, 0.9 to 1.6, and 111 to 237 g kg(-1), respectively. Cocoyam starches gave higher potassium and phosphorus but lower calcium levels than the other starches. The shape of starch granules varied from spherical to polygonal with cocoyam starches displaying smaller-sized granules than cassava and corn starches. Cocoyam starches gave a higher wavelength of maximum iodine absorption and blue value but lower reducing capacity values than cassava and corn starches. The extent of acid hydrolysis of the starches also differed. Cocoyam starches exhibited amylopectin molecules of higher molecular weights but amylose molecules of lower molecular weights than cassava and corn starches. Cocoyam starches exhibited lower water absorption capacity and swelling power, paste clarity and viscosity but higher solubility, gelatinisation temperatures and retrogradation tendencies than cassava and corn starches.

CONCLUSIONS

The physicochemical properties of native Malawian cocoyam starches vary among the different accessions and differ from those of cassava and corn starches.