Effect of additives on gelatinization, rheological properties and biodegradability of thermoplastic starch

Effect of additives on the starch gelatinization was governed by the processing conditions. The order-disorder transition of starch in water can occur in more than one way and the effect of polar additives on gelatinization can also be in more than one way. The additives appear to be plasticising thermoplastic starches, resulting in improving rheological properties. The thermoplastic starches with the additives are all biodegradable although the rates of biodegradability are slightly different.

Effect of honey types and concentration on starch gelatinization

The complex and variable composition of honey, depending on source, season and processing, means different honey samples could cause variation in the characteristics of the finished product. The objective of this study was to determine how the minor components present in honey affect starch gelatinization. A Rapid Visco Analyser was used to measure changes in viscosity when unmodified maize starch was gelatinized in a honey or model sugar solution. When honey was compared to equivalent blends of sugars, there was an increase in starch viscosity with increasing levels of addition. However, at the same level, honey gave a lower viscosity than the blends of sugars. Honeys from different sources (differing in pH and amylase activity) show a varied effect on starch gelatinization, with starch viscosity increasing with addition level for six of the honeys, but decreasing with increasing addition level for two honey samples. Varying the pH also produced variation in starch gelatinization patterns between honey types. Between pH 3.0 and 4.0, starch viscosity was similar for all four honey types studied, while above this pH there were differences between all honey types. As expected, starch viscosity decreased as the solution pH neared the optimum for honey amylase activity (pH 5.3-5.6), though it did not increase as the pH moved away from the honey amylase activity optimum. Differences between honey samples, and between honey and a model sugar mixture, in their effect on starch gelatinization was attributed to honey amylase activity and the composition and concentration of minor organic compounds present. Crown Copyright (C) 2003 Published by Elsevier Ltd. on behalf of Swiss Society of Food Science and Technology

Effects of starch gelatinization and oxidation on the rheological behavior of chitosan/starch blends

Chitosan/starchblends represent an interesting alternative for the preparation of biocompatible drug delivery systems, packing materials and edible films. This paper reports on the effects of starch gelatinization and oxidation on the rheological behavior of chitosan/starch blends. The results show that the modifications in the starch structure cause changes in G` (storage modulus) and G `` (lossmodulus) as a function of frequency. For chitosan/starch, G `` is higher than G`, showing a viscous behavior. However, for chitosan/gelatinized starch and chitosan/oxidized starch, an increase in the angular frequency promotes a modulus crossover at omega = 0.02 and 0.04 rad s(-1), respectively. The viscosity curves as a function of shear rate show that both modifications cause an increase in viscosity, and all blends show a non-Newtonian behavior. (C) 2011 Society of Chemical Industry

Gelatinization properties of native starches and their Naegeli dextrins

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of glycerol monostearate on the gelatinization behavior of maize starches with different amylose contents

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of the particle size of maize, rice, and sorghum in extruded diets for dogs on starch gelatinization, digestibility, and the fecal concentration of fermentation products

The influence of rice, maize, and sorghum raw material particle size in extruded dry dog food on the digestibility of nutrients and energy and the fecal concentration of fermentation products was investigated. Three diets with similar nutrient compositions were formulated, each with 1 starch source. Before incorporation into diets, the cereals were ground into 3 different particle sizes (approximately 300, 450, and 600 mu m); therefore, a total of 9 diets were in a 3 x 3 factorial arrangement (3 cereals and 3 particle sizes). Fifty-four beagle dogs (12.0 +/- 0.1 kg BW) were randomly assigned to the diets, with 6 dogs per diet. The digestibility was measured with the chromium oxide method. The data were evaluated with ANOVA considering the carbohydrate source, grinding effect, and interactions. The means were compared with the Tukey test and polynomial contrasts (P < 0.05). With the same grinding procedure, rice was reduced to smaller particles than other cereals. The cereal mean geometric diameter (MGD) was directly related to starch gelatini-zation (SG) during extrusion. For rice diets, the MGD and SG did not change nutrient digestibility (P > 0.05); only GE digestibility was reduced at the largest MGD (P < 0.01). For maize and sorghum diets, the total tract apparent nutrient digestibility was reduced for foods with greater MGD and less SG (P < 0.01). A linear reduction in nutrient digestibility according to cereal particle size was observed for sorghum (r(2) < 0.72; P < 0.01). Higher concentrations of fecal total shortchain fatty acids (SCFA) were observed for sorghum diets (P < 0.05) than for other diets. The rice diets led to the production of feces with less lactate (P < 0.05). The increase in raw material MGD did not influence fecal SCFA for rice diets, but for the dogs fed maize and sorghum foods, an increase in propionate and butyrate concentrations were observed as MGD increased (P < 0.05). In conclusion, for dogs fed different particle sizes of the cereal starches in the extruded diets, the digestibility and fecal characteristics were affected, and this effect was ingredient dependent.

Gelatinization of starch in mixed sugar systems

Sugars affect the gelatinization of starch, with the effect varying significantly between sugars. Since many food products contain a mixture of sugar sources, it is important to understand how their mixtures affect starch gelatinization. In a Rapid Visco Analyser study of maize starch gelatinization, changing proportions in binary mixtures of refined sugars saw a largely proportionate change in starch gelatinization properties. However, binary mixture of pure sugars and honey, or a model honey system (the main sugars in honey) and honey responded differently. Generally, replacing 25% or 50% of the refined sugar or model honey system with honey gave a large change in starch gelatinization properties, while further increases in honey level had little further effect. Differences between honey and buffered model honey system (either gluconic acid, or a mixture of citric acid and di-sodium phosphate) showed the sensitivity of starch gelatinization to the composition of the nonsaccharide component. (c) 2004 Swiss Society of Food Science and Technology. Published by Elsevier Ltd. All rights reserved.

Rheological and functional properties of flours from banana pulp and peel

Unripe banana flour can be an alternative to minimize post-harvest loss and to increase the aggregate value of banana fruit. Flour from unripe banana is rich in phytosterols and resistant starch, being proposed as health food. Flours from unripe banana peel and pulp were evaluated on their composition, phytosterols content, thermal and rheological properties, and pasting profiles. High amounts of beta-sitosterol, campesterol, and stigmasterol were found in flour from banana peel. These samples showed lower viscosity values of pasting profiles, lower energy enthalpy on gelatinization, and higher temperature of gelatinization than those ones from pulp. Anti-oxidant treatment of fruits with citric acid does not change pasting profiles of flours from pulp, but resulted in slight increase in viscosity, suggesting that structure of starch could be modified by acidification.

Thermal properties and resistant starch content of green banana flour (Musa cavendishii) produced at different drying conditions

The objective of this research was to verify the effect of drying conditions on thermal properties and resistant starch content of green banana flour (Musa cavendishii). The green banana flour is a complex-carbohydrates source, mainly of resistant starch, and quantifying its gelatinization is important to understand how it affects food processing and the functional properties of the flour. The green banana flour was obtained by drying unripe peeled bananas (first stage of ripening) in a dryer tunnel at 52 degrees C, 55 degrees C and 58 degrees C and air velocity at 0.6 m s(-1), 1.0 m s(-1) and 1.4 m s(-1). The results obtained from differential scanning calorimetry, (DSC) curves show a single endothermic transition and a flow of maximum heating at peak temperatures from (67.95 +/- 0.31)degrees C to (68.63 +/- 0.28) degrees C. ANOVA shows that only drying temperature influenced significantly (P < 0.05) the gelatinization peak temperature (Tp). Gelatinization enthalpy (Delta H) varied from 9.04 J g(-1) to 11.63 J g(-1) and no significant difference was observed for either temperature or air velocity. The resistant starch content of the flour produced varied from (40.9 +/- 0.4) g/100 g to (58.5 +/- 5.4) g/100 g, on dry basis (d. b.), and was influenced by the combination of drying conditions: flour produced at 55 degrees C/1.4 m s(-1) and 55 degrees C/1.0 m s(-1) presented higher content of resistant starch. (c) 2009 Elsevier Ltd. All rights reserved

Physical-chemical and functional properties of maca root starch (Lepidium meyenii Walpers)

The starch of maca (Lepidium meyenii Walpers) presented oval and irregular morphology, with granule size between 7.4 and 14.9 mu m in length and 5.8 and 9.3 mu m in diameter. The isolated starch showed the following features: purity of 87.8%, with 0.28% lipids, 0.2% fibre and 0.12% fixed mineral residue, and no protein detected; the ratio between the amylose and amylopectin contents were 20:80: the solubility at 90 degrees C was 61.4%, the swelling power was 119.0g water/g starch and the water absorption capacity was 45.9 g water/g starch; the gel turbidity rose 44% during the storing time; the gelatinization temperature was 47.7 degrees C and the transition enthalpy 6.22 J/g; the maximum viscosity reached 1260 UB at 46.4 degrees C, with breakdown, setback and consistence of 850, 440 and -410 UB, respectively. The low gelling temperature and the stability during gel refrigeration could be adequate for foods requiring moderate temperature process, but not for frozen food. (C) 2008 Elsevier Ltd. All rights reserved.

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 10degreesC, 20degreesC and 30degreesC, 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 (30degreesC) 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 10degreesC 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. 10degreesC) and high RH (e.g. 65%). (C) 2003 Swiss Society of Food Science and Technology. Published by Elsevier Science Ltd. All rights reserved.

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. (C) 2010 Society of Chemical Industry

Plantain and Banana Starches: Granule Structural Characteristics Explain the Differences in Their Starch Degradation Patterns

Different banana cultivars were used to investigate the influences of starch granule structure and hydrolases on degradation. The highest degrees of starch degradation were observed in dessert bananas during ripening. Scanning electron microscopy images revealed smooth granule surface in the green stage in all cultivars, except for Mysore. The small and round granules were preferentially degraded in all of the cultivars. Terra demonstrated a higher degree of crystallinity and a short amylopectin chain length distribution, resulting in high starch content in the ripe stage. Amylose content and the crystallinity index were more strongly correlated than the distribution of amylopectin branch chain lengths in banana starches. alpha- and beta-amylase activities were found in both forms, soluble in the pulp and associated with the starch granule. Starch-phosphorylase was not found in Mysore. On the basis of the profile of alpha-amylase in vitro digestion and the structural characteristics, it could be concluded that the starch of plantains has an arrangement of granules more resistant to enzymes than the starch of dessert bananas.

Gastrointestinal transit of extruded or pelletized diets in pacu fed distinct inclusion levels of lipid and carbohydrate

The objective of this work was to evaluate the effect of pelletized or extruded diets, with different levels of carbohydrate and lipid, on the gastrointestinal transit time (GITT) and its modulation in pacu (Piaractus mesopotamicus). One hundred and eighty pacu juveniles were fed with eight isonitrogenous diets containing two carbohydrate levels (40 and 50%) and two lipid levels (4 and 8%). Four diets were pelletized and four were extruded. Carbohydrate and lipid experimental levels caused no changes to the bolus transit time. However, the bolus permanence time was related to diet processing. Fish fed pelletized diets exhibited the highest gastrointestinal transit time. Regression analysis of bolus behavior for pelletized and extruded diets with 4% lipid depicted different fits. GITT regression analysis of fish fed 8% lipid was fitted to a cubic equation and displayed adjustments of food permanence, with enhanced utilization of the diets, either with extruded or pelletized diets. GITT of fish fed extruded diets with 4% lipid was adjusted to a linear equation. The GITT of pacu depends on the diet processing and is affected by dietary levels of lipid and carbohydrate.

Estudo termogravimétrico e calorimétrico da algaroba

Humidity and ash content of powder and bran of algaroba pods are important quality parameters for biological control during storage. The studies of humidity and ash content were carried out conventional and thermogravimetric methods. Different values were obtained by the various methods. The thermogravimetric method was faster and required less sample for the humidity and ash analyses of the powder and bran of algaroba pods. The differential scanning calorimetry curves of the powder and bran of algaroba pods, dryed at 55 ºC, showed two peaks, one corresponding to the gelatinization of starch and the other to the vaporization of water. The samples dryed at 65, 75, 85, 95 and 105 ºC showed one peak, corresponding to the vaporization of water.