Impact of thermo-sonication on quality indices of starch-based sauces

In this study, ultrasonication, a physical, relatively cheap, and environmentally benign technology, was investigated to characterize its effect on functional properties of rice starch and rice starch-based sauces. Temperature-assisted ultrasound treatment improved the granular swelling power, fat and water absorption capacities, and thermal properties of rice starch, signifying its suitability in the formulation of starch-based sauces. Rheological characterization of the formulated sauces revealed a shear-thinning flow behavior, well described by the Ostwald de Waele model, while viscoelastic properties showed the existence of a weak gel. Results indicated that ultrasonication significantly enhanced the pseudoplastic behavior of starch-based sauces. Additionally, textural analysis showed that textural attributes (stickiness, stringiness, and work of adhesion) were also improved with ultrasonication. Moreover, enhanced freeze/thaw stability was also achieved with ultrasound-treated starch-based sauces. Overall, the results from this study show that ultrasound-treated starches can be used in the formulation of sauces and potentially other food products, which meets the requirements for clean label and minimally processed foods.

Combined effects of Wx and SSIIa haplotypes on rice starch physicochemical properties

BACKGROUND

Wx and SSIIa are central genes for determining starch physicochemical properties and rice endosperm starch is composed of linear amylose, which is entirely synthesized by granule bound starch synthase I (GBSSI, encoded by Wx) and branched amylopectin. In the present study, different haplotypes of rice were examined to investigate the combined effects of pivotal genes in the metabolic chain of starch, Wx and SSIIa.

RESULTS

Wx haplotypes differed in terms of apparent amylose content (AAC) and gel consistency (GC). The I-3 [haplotype I (Int1T/Ex10C) of Wx and haplotype 3 (A-G-TT) of SSIIa] and the I-4 combinations of rice had better eating and cooking qualities (ECQs) with lower AAC, lower gelatinization temperature (GT) and softer GC.

CONCLUSION

The characteristic parameters of Rapid Visco-analyser (RVA) could distinguish differences in AAC and GC but not GT. The I-3 and I-4 haplotype combinations of Wx and SSIIa represent key targets for the production of rice with better ECQs. © 2016 Society of Chemical Industry.

Functional Properties of Glutinous Rice Flour by Dry-Heat Treatment

Glutinous rice flour (GRF) and glutinous rice starch (GRS) were modified by dry-heat treatment and their rheological, thermal properties and freeze-thaw stability were evaluated. Compared with the native GRF and GRS, the water-holding ability of modified GRF and GRS were enhanced. Both the onset and peak temperatures of the modified samples increased while the endothermic enthalpy change decreased significantly (p < 0.05). Meanwhile, dry heating remarkably increased the apparent viscosities of both GRF and GRS. Importantly, compared with GRS samples, the storage modulus (G') and loss modulus (G") values of modified GRF increased more greatly and the tanδ values decreased more remarkably, indicating that the dry-heat treatment showed more impact on the GRF and a higher viscoelasticity compared with GRS. Our results suggest the dry-heat treatment of GRF is a more effective method than that of GRS, which omits the complex and tedious process for purifying GRS, and thereby has more practical applications in the food industry.

Effect of heat treatment on quality, thermal and pasting properties of sweet potato starch during yearlong storage

BACKGROUND

Proper postharvest handling and storage of sweet potato is an important link in the chain from producer to consumer or manufacturing industry. Heat treatments have been used as a non-chemical means to modify the postharvest quality and reduce pathogen levels and disease development of a wide variety of horticultural products. The objective of this study was to investigate the effects of hot water treatment (HWT) on the quality, gelatinisation enthalpy and pasting properties of sweet potato starch during long-term storage. The weight loss, sprouting, spoilage and sugar content of sweet potato were also determined.

RESULTS

HWT significantly inhibited the sprouting and decay of sweet potato during the storage period. There were no significant differences (P < 0.05) in the pasting properties and onset (T(O)), peak (T(P)) and endset (T(E)) temperatures of gelatinisation of sweet potato starch among all treatments, especially between heat-treated and non-heat-treated samples. HWT also had no significant impact on the quality of the internal components of the roots. Less than 4% of the yearlong-stored roots were discarded owing to spoilage. HWT supplied a lethal dose of heat to surface pathogens and black spot without damaging the nutritional and processing qualities of sweet potato.

CONCLUSION

HWT was an effective method to reduce root sprouting and deterioration without significant impact on the quality of the internal components of sweet potato. This novel technique will open a new avenue to extend the storage life of sweet potato with good quality and minimal waste.

Association between nonsynonymous mutations of starch synthase IIa and starch quality in rice (Oryza sativa)

Starch quality is one of the most important agronomic traits in Asian rice, Oryza sativa. Starch synthase IIa (SsIIa) is a major candidate gene for starch quality variation. Within SsIIa, three nonsynonymous mutations in exon 8 have been shown to affect enzyme activity when expressed in Escherichia coli. To search for the variation in SsIIa that is responsible for starch quality variation in rice, we sequenced the SsIIa exon 8 region and measured starch quality as starch disintegration in alkali for 289 accessions of cultivated rice and 57 accessions of its wild ancestor, Oryza rufipogon. A general linear model and nested clade analysis were used to identify the associations between the three nonsynonymous single nucleotide polymorphisms (SNPs) and starch quality. Among the three nonsynonymous SNPs, we found strong evidence of association at one nucleotide site ('SNP 3'), corresponding to a Leu/Phe replacement at codon 781. A second SNP, corresponding to a Val/Met replacement at codon 737, could potentially show an association with increased sample sizes. Variation in SsIIa enzyme activity is associated with the cohesiveness of rice grains when cooked, and our findings are consistent with selection for more cohesive grains during the domestication of tropical japonica rice.

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.

Potential of Amaranthus cruentus BRS Alegria in the production of flour, starch and protein concentrate: chemical, thermal and rheological characterization

BACKGROUND

Amaranth is a little-known culture in Brazilian agriculture. Amaranthus cruentus BRS Alegria was the first cultivar recommended by Embrapa for the soil of the Brazilian scrubland. In order to evaluate the potential of this species in the production of flour, starch and protein concentrates, the latter products were obtained from A. cruentus BRS Alegria seeds, characterized and compared with the products obtained from the A. caudatus species cultivated in its soil of origin.

RESULTS

The seeds of A. cruentus BRS Alegria furnished high-purity starch and flour with significant content of starch, proteins, and lipids. The starch and flour of this species presented higher gelatinization temperatures and formed stronger gels upon cooling compared with those obtained from the A. caudatus species. This is due to their greater amylose content and a difference in the composition of the more important fatty acids, such as stearic, oleic and linoleic acids, which indicates that they have greater heat stability. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and differential scanning calorimetry revealed the presence of albumins, globulins, glutelins and prolamins in the protein concentrate, which was obtained as a byproduct of starch production.

CONCLUSION

Amaranthus cruentus BRS Alegria has potential application in the production of flour, starch and protein concentrates, with interesting characteristics for use as food ingredients.

[Evaluation of the flour and starch from white and purple varieties of mapuey (Dioscorea trifida)]

Mapuey (Dioscorea trifida), is a tropical America tuber, which is appreciated for its taste and fine texture. It has not been fully cultivated in Venezuela, even though products like its flour and starch could replace conventional used products. In this work physical and chemical characteristic of flours from mapuey (varieties white and purple), were assessed, as well as some of their micronutrients. Physical, physicochemical and rheological properties, and chemical composition of isolated starches were also evaluated. Flours were obtained by a drying process and starches by aqueous extraction. Chemical analysis was performed following standard methodologies. The flour yield of purple mapuey was the highest, as was its protein content. The minerals content, showed significant differences between both varieties, presenting purple variety a higher content. Isolated starches showed high purity, this was corroborated by the scanning electron microscopy which showed irregular shaped granules (oval and elongated), with truncated end and smooth surfaces. Purple mapuey granules were smaller. Both varieties exhibited a B type diffraction pattern. The greater swelling power and water absorption capacity was presented by white mapuey, while the highest solubility was shown by the purple one. The white mapuey had maximum viscosity, as well as the highest value of breakdown, suggesting more fragile granules. Setback was lower in the white mapuey, suggesting lower tendency to retrogradation. The purple mapuey although, it showed a higher amylose content, presented lower consistency, even though the difference was not relevant.

Towards the rational design of cereal starches

A major challenge in cereal biotechnology is to achieve the rational design of renewable polymers to meet specific requirements for improving human health, nutrition, and food quality, to increase the energy supply, and to provide safer and more profitable industrial inputs. The field of starch synthesis research has advanced at a rapid pace over the past decade, and many core observations about the pathway are well established over a range of species. Owing to the complexity of the starch-synthesis process, in which suites of enzymes act at the interface between soluble and insoluble phases, the rational design of starch granules with specific functionality is still in its infancy. Our fundamental biochemical knowledge of starch biosynthesis has recently advanced, and this new information could be exploited to create novel variability in carbohydrate polymers in cereal grains. We propose two strategies for moving more rapidly towards truly rational design of starch. First, the focusing of fundamental research on processes that are involved in the regulation of starch synthesis and granule assembly. Second, the development of iterative strategies, exploiting new molecular genetics tools, to screen for desired properties in high-throughput systems.

Whole-grain consumption and chronic disease: protective mechanisms

Dietary guidance recommends consumption of whole grains to reduce the risk of chronic diseases including cancer and cardiovascular disease. Epidemiologic studies support the belief that whole grains are protective against cancers, especially gastrointestinal cancers such as gastric and colonic, and cardiovascular disease. Components in whole grains that may be protective are diverse and include compounds that affect the gut environment, i.e., dietary fiber, resistant starch, and other undigestible compounds in whole grains, compounds that function as antioxidants such as trace minerals and phenolic compounds, and compounds that are phytoestrogens with potential hormonal effects. Many of the protective compounds in whole grains are also in fruits and vegetables, but some plant compounds are more concentrated in whole grains, such as phenolic compounds including ferulic and caffeic acid. Other potential mechanistic effects of whole grains include binding of carcinogens and modulation of glycemic index. Clearly, the range of protective substances in whole grains is impressive, and advice to consume additional whole grains is justifiable.

Sourdough fermentation or addition of organic acids or corresponding salts to bread improves nutritional properties of starch in healthy humans

Postprandial blood glucose and insulin responses to barley bread containing organic acids or corresponding salts were evaluated in healthy human subjects. The satiety score and the rate and extent of in vitro starch digestion were also studied. Lactic acid was generated by use of a homofermentative starter culture or added to the dough. In addition, products were baked with Ca-lactate, or with Na-propionate at two different concentrations. Consumption of the product baked with a high concentration of Na-propionate significantly lowered the postprandial blood glucose and insulin responses, and significantly prolonged the duration of satiety compared with all other breads. When subjects consumed the breads baked with sourdough, lactic acid and Na-propionate, their glucose and insulin responses were reduced compared with the wholemeal bread alone. The rate of in vitro amylolysis was reduced only by ingestion of the breads containing lactic acid, suggesting that the beneficial impact of Na-propionate on metabolic responses and satiety was related to effects other than a reduced rate of starch hydrolysis. All bread products had a similar concentration of in vitro resistant starch of 1.3-2.1 g/100 g (starch basis). It is concluded that sourdough baking and other fermentation processes may improve the nutritional features of starch. The results also demonstrate that certain salts of organic acids may have metabolic effects.

Effect of substitution of starch for fiber and fat in isoenergetic diets on nutrient digestibility and reproductive performance of rabbits

The optimal level of starch in diets for rabbit does was investigated. Five isoenergetic and isoproteic diets containing 26.6, 24.6, 19.0, 16.8, or 13.0% starch and 31.2, 33.4, 36.0, or 41.2% NDF, respectively (DM basis), were made by substitution of starch for NDF and fat. The effect of diet on nutrient digestibility was determined in fattening and nonlactating and lactating adult does using a total of 105 rabbits. Increasing dietary starch content linearly increased (P < .001) DM, GE, CP (P = .07), and starch digestibilities but decreased (P < .001) NDF digestibility. Nutrient digestibility was higher (P < .05), except for CP, in adult does than in fattening rabbits. Dry matter and GE digestibilities were higher (P = .08) for nonlactating than for lactating does. A lactation trial using 440 rabbit does was conducted over a 6-mo experimental period. Milk production and milk composition were measured in 70 lactations. A decrease in dietary starch content did not improve pup mortality before weaning but impaired (linear, P < .001) dry feed intake and pup growth from 21 d until weaning. Diet did not influence does' feed intake, milk DM, ether extract, and CP contents or prolificacy. However, diet had quadratic effects on milk production (P = .15), milk lactose content (P = .07), parturition interval (P = .02), and feed conversion efficiency (P = .02), expressed both per weight or number of pups weaned. Optimal values were reached for dietary starch and NDF contents at approximately 20 and 35.5% (DM basis), respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Intragranular starch: comparison of starch USP and modified cornstarch

Incorporation of starch USP or a modified cornstarch within the granules of several drug formulations was investigated. In general, the formulation containing the modified starch exhibited improved processing characteristics as well as improved tablet properties. A comparison of a granulated and a direct compression formulation of the same ingradients indicated that granulation of an active ingredient is not necessarily detrimental to its (pharmaceutical) availability.