Sorption Isotherms of Barnyard Millet Grain and Kernel

The moisture sorption isotherms of grain and kernel of barnyard millet (Echinochloa frumentacea) were determined at 20, 30, 40, and 50 °C. A gravimetric static method was used under 0.112–0.964 water activity (a _w) range for the determination of sorption isotherms. The models were compared using the coefficient of determination (r ²), reduced chi-square (χ ²) values, and on the basis of residual plots. In grain, modified Chung–Pfost (r ² > 0.99; χ ² < 0.7) and modified Oswin (r ² > 0.99; χ ² < 0.55) models were found suitable for predicting the M _e –a _w relationship for adsorption and desorption, respectively. Modified Henderson model was found to give the best fit (r ² > 0.99 and χ ² < 0.55) for describing the adsorption and desorption of the kernel. The isosteric heat, calculated using Clausius–Clapeyron equation, was varied between 46.76 and 61.71 kJ g⁻¹ mol⁻¹ at moisture levels 7–21% (d.b.) for grain and 47.11–63.52 kJ g⁻¹ mol⁻¹ at moisture level between 4% and 20% (d.b.) for kernel. The monolayer moisture content values ranged from 4.3% to 6% d.b. in the case of adsorption of barnyard millet grain and 5.2–6.6% d.b. in the case of desorption at the temperature ranges of 50–20 °C. The monolayer moisture values of barnyard millet kernel ranged from 4.4% to 6.67% d.b. in adsorption and 4.6% to 7.3% d.b. in desorption in the temperature ranges of 50–20 °C.     

Effect of Process Parameters on Work Index, Milling Efficiency and Some Technological Properties of Yam Flour Using Attrition Mill

The effect of process parameters on work index, efficiency of milling, bulk density, swelling capacity and water absorption capacity of yam flour using attrition mill was studied. Independent variables were: moisture content (8, 12, 16, 20 and 24 % w.b.), speed (288, 346, 432, 576 and 864 rpm) and inlet opening (1,300, 2,600, 3,900, 5,200 and 6,500 mm²). The responses were work index, milling efficiency, bulk density, water absorption and swelling capacities of the flour. Work indexes for milling yam flour, meal and grit were found to be 0.25?±?0.13, 0.49?±?0.14 and 1.8?±?0.56, respectively. Flour fraction, bulk density, water absorption capacity and swelling capacity ranged from 42.2 to 56.6 %, 0.54 to 0.66 g/m³, 200 to 400 % and 13 to 23 ml, respectively. The treatments were found to influence the responses significantly (p?<?0.05). Optimum process condition was achieved at 12 % moisture content of feed, 506 rpm shaft speed and 5,200 mm² feed opening giving 19.1 % grit, 23.6 % meal and 54.2 % flour. The desirability of the optimisation process was 0.78. Validation of predicted optimal moisture content, worm shaft speed and feed inlet opening gave errors of 19, 14.4 and 6.1 % for grit, meal and flour, respectively.     

Rheology and Expansion of Starch-Water-CO2 Mixtures with Controlled Gelatinization by Supercritical Fluid Extrusion

A slit die rheometer fitted to a twin-screw extruder was used to measure the viscosity and expansion characteristics of starch-based melts plasticized with water and supercritical CO₂. Experiments were conducted for four intermediate moisture starch-water mixtures with varying degree of starch gelatinization (DG), achieved by blends of pregelatinized and native common corn starch. SC-CO₂ was shown to be an effective plasticizer for starch-water mixture at 0.45 g SC-CO₂/100 g sample, lowering the viscosity of the melt by an average of 14%. Apparent viscosity was measured for shear rate ranging from 100–200 s^?1. The viscosity reduction factors based on DG and SC-CO₂ indicated that the free volume added to starch-water mixtures with SC-CO₂ is an effective mechanism for viscosity reduction. In addition, the higher water affinity of pregelatinized starch increased the water induced plasticization effect in the mixtures. SC-CO₂ was a good blowing agent producing distinct expanded microcellular morphology for the starch-water mixtures with DG at or above 80%. The expansion and cellular characterization of these starch-based extrudates produced by SC-CO₂ injection may be governed by the viscosity-dependent parameters including gas retention capability, CO₂ diffusivity and the pressure drop rate.     

Effect of extrusion conditions on the physicochemical properties of a snack made from purple rice (Hom Nil) and soybean flour blend

Soy flour was added at levels of 5%, 10%, and 15% of Hom Nil rice flour for extrusion at 190 °C barrel temperature and 350 rpm screw speed. The extruded snack qualities decreased inversely with soy flour. However, product qualities were considered to be optimised when soy flour at 5% was added. The effect of feed moisture content (15, 17, 19 g (100 g)^?1 wb), barrel temperature (150, 170, 190 °C) and screw speed (350, 400, 450 rpm) on physicochemical properties of the snack were then investigated. The physicochemical properties of the product including expansion ratio, density, water absorption index (WAI), water solubility index (WSI) and hardness were evaluated. All properties were related, as linear equations, in terms of feed moisture content, barrel temperature, screw speed with relative correlation (R²) at 0.83–0.94. The snack properties along with consumer acceptance were all highest when the extruded condition were 15 g (100 g)^?1 wb feed moisture content, 170 °C of barrel temperature and 450 rpm of screw speed.     

Effect of Germination on the Functional and Moisture Sorption Properties of High–Pressure-Processed Foxtail Millet Grain Flour

Foxtail millet is one of the commonly cultivated, nutritionally competitive source of protein, fibre, phytochemicals and other micronutrients, as compared to major cereals like wheat and rice. Considering the potential of these grains, the high pressure processed flours of germinated (GFMF) and non-germinated foxtail millet (NGFMF) grains were studied for its functional, moisture sorption and thermodynamic properties. Germination and high-pressure processing of foxtail millet grains significantly improved the functional properties of the flour. Apart from this, the moisture sorption isotherms of both the flours were determined at 10, 25 and 40 °C and the sorption data was fitted to Guggenheim-Anderson-De Boer (GAB) sorption model. The monolayer moisture content for NGFMF and GFMF ranged between 3.235–2.364 and 2.987–2.063 g g^?1, respectively. The isosteric heat of sorption ranged between ? 76.35 to ? 38.23 kJ mol^?1 for NGFMF and 172.55 to ? 34.02 kJ mol^?1 for GFMF at a moisture range of 0 to 36%, whereas, the integral entropy of sorption for NGFMF ranged between ? 0.404 and ? 0.120 kJ mol^?1 K^?1 and for GFMF between ? 0.667 and ? 0.383 kJ mol^?1 K^?1. Along with the validation of the compensation theory, the values of spreading pressures lied in the range of 0–0.078 J m^?2 for NGFMF and 0– 0.124 J m^?2 for GFMF, while, the glass transition temperatures ranged between 82.25 and 28.67 °C for NGFMF and from 51.11 to 11.83 °C for GFMF at all three temperatures.     

Effects of different types and concentrations of thickeners on yoghurt protein bioaccessibility by an in vitro dynamic gastrointestinal digestive model

This study analysed the protein bioaccessibility of yoghurt containing different concentrations of pectin, acid-resistant carboxymethylcellulose (CMC), guar gum and xanthan gum before and during in vitro gastrointestinal digestion, respectively. Soluble protein contents and protein digestion rates of yoghurt with 0.2% (m/v) guar gum, CMC and xanthan gum were significantly higher and faster, whereas other thickeners had slower rates than control yoghurt during gastric digestion phase. In addition, the contents of small peptides and amino acids were higher in yoghurt with 0.2% (m/v) thickeners than those with 1.0% (m/v) thickeners during simulated intestinal digestion in most of the samples.     

Water sorption and cooking time of red kidney beans (Phaseolus vulgaris L.): part II – mathematical models of water sorption

Empirical, semi‐theoretical and finite element method (FEM) models were developed to simulate the water sorption of kidney beans. The data of bean moisture content and 1 D swelling ratios obtained in Part I were regressed at different soaking times, and these regression models were used to update the boundary condition and calculate the node coordinates of the FEM model. The developed models were used to calculate the effective water diffusivity (D_eff). The developed new empirical model, which considered the soaking temperature and pretreatment history of beans, was the best‐fit equation. The trend of the D_eff calculated by the semi‐theoretical model was inconsistent with the water sorption of the beans. The D_eff value predicted by the FEM was from 10^?3 to 10^?7 m² s^?1 and it decreased with the increase in soaking time. There was no significant difference between the moisture contents measured and predicted by the FEM.     

Effects of high energy milling on some functional properties of jicama starch (Pachyrrhizus erosus L. Urban) and cassava starch (Manihot esculenta Crantz)

In this study, the effect of high energy milling using a Spex ball mixer mill on some functional properties of cassava starch (Manihot utilissima) and jicama starch (Pachyrrisus erosus) were investigated. The properties of individual granules were strongly influenced by the high moisture of ball milling (friction and heat) and physicochemical properties of their amorphous and crystalline zones. High energy milling resulted in a partial fragmentation of the starch granules, increasing the water absorption index (WAI) and the water solubility index (WSI). Increasing moisture content the viscosity was decreased, attributable to the fragmentation of starch granules produced by the milling and favored by the increase of moisture content.The crystallinity of cassava and jicama starches milled with high moisture contents and longer milling times was decreased. Thermal properties of both ball-milled starches were modified. The enthalpies were lower than native starch indicating that ball milling destroys the crystallinity and double helical order arrangements. Also, the resolution of the peaks was slightly decreased. Ball-milled jicama and cassava starches showed some functional characteristics of gelatinization that possibility their use in food systems as stabilizing, additives, moisture retainers and thickeners.     

OPTIMIZATION OF CORNSTARCH/XANTHAN GUM CONTENT FOR THICKENING OF COCOA SYRUPS

ABSTRACT

Blended cornstarch–xanthan gum systems were optimized for thickening of cocoa syrups. For this purpose the sensory (whole and partial), textural (force of penetration, adhesiveness and stringiness) and rheological properties (flow curves as well as viscosity/time and viscosity/temperature relationships) of cocoa syrups were studied. Flow curves were described by rheological model of Casson, which accounted syrups under study for non‐Newtonian, pseudoplastic and thixotropic fluids. Also models of Weltman and Arrhenius were applied for comparison of obtained data. The areas of thixotropy hysteresis loops were also calculated. Obtained data (sensory, textural and rheological) were used as a base for mathematical calculations. The results were presented in the tables to enable their easier understanding. As a result, optimization of thickeners was achieved – the best ranges of cornstarch (0.45–0.49%) as well as xanthan gum (0.15–0.17%) concentrations in cocoa syrups were selected.

PRACTICAL APPLICATION

The result of this study could be used as a guide for thickening of cocoa syrups by the application of cornstarch–xanthan gum combination, chemically nonmodified thickeners. Mathematical method tried in this study for optimization of thickeners addition could be useful for optimization of the other thickeners and additives employed for different sauces, syrups, dressings, ketchups, mayonnaises, etc.

     

Extrusion of Maize–Cowpea Blends in a Modified Oil Expeller

A laboratory oil expeller was modified by using a press cylinder without openings for expelling the oil. Central composite rotatable design for k=3 was used to study the effects of process variables, cowpea level (0–25%), feed moisture (10–25%) and barrel temperature (130–200°C) on product indices (moisture, expansion index, bulk density, water absorption, extractable solids, swell volume and the degree of gelatinisation of flour from the extrudate). Regression models developed to predict product indices were significant and showed no significant lack of fit. The model for moisture content of the extrudate had an R² of 0·98. Product moisture was influenced by the amount of cowpea in the feed, the temperature of extrusion and feed moisture. Furthermore, the product moisture measured at each cowpea level was dependent on the temperature of extrusion. The model for product expansion index showed that this index decreased with feed moisture and the cowpea level. Regression models for bulk density, water absorption, extractable solids and the maximum swell volume of flour from the extrudate were influenced by the process variables. The degree of gelatinisation decreased with cowpea level and increased with extrusion temperature. © 1997 SCI.     

Effect of Mesona Blumes gum on physicochemical and sensory characteristics of rice extrudates

The aim of this study was to evaluate effects of Mesona Blumes gum (MBG) on some physical, chemical, sensory and antioxidant properties of rice extrudates. MBG was added to rice flour at 0%, 5%, 10%, 15% and 20% (w/w). The water solubility index (WSI) increased from 4.19% to 15.32% with MBG addition. Both water absorption index (WAI) and moisture retention (MR) reached maximum at 15% MBG. Bulk density (BD) was the highest at 5% (131.22 g cm^?3) and the lowest at 15% MBG (121.44 g cm^?3). Hardness was maximal at 5% (8.44 N mm^?2) and minimal at 15% MBG (5.98 N mm^?2). Expansion ratio (ER) and lightness (L*) decreased for all extruded products with MBG. MBG at 5% or 10% level could improve sensory characteristics of final products. The extract of extrudates at 15% MBG had the highest antioxidation ability among those extrudates. Thus, it was possible to produce a new palatable rice extrudate with MBG.     

Thermodynamic properties of moisture adsorption of whole wheat flour. Calculation of net isosteric heat

The moisture sorption isotherms of whole wheat flour were determined at 10, 20 and 30 °C over a relative humidity range of 10–90%. Two models were applied to the sorption experimental data: the Guggenheim–Anderson–de Boer (GAB) and the Caurie models. The goodness of fit of the mathematical models was statistically evaluated by means of the root mean square per cent error (%RMS), obtaining values between 1.44 and 1.05 for GAB, and between 2.69 and 2.57 for the Caurie model. Hence, both models provided a good fit to the experimental data. The isosteric heat of sorption was calculated using two methods: the Clausius–Clapeyron expression and the Caurie equations, showing in both cases maximum values (11.03 and 12.39 kJ mol^?1, respectively) when moisture content was minimum (2.5 g H₂O per 100 g dry matter), and gradually diminishing to the value of the heat of vaporisation of pure water when moisture content reached a maximum value.     

Unlocking the potential of pasting properties to predict extrudate characteristics of corn grits blends with high amylose corn starch,potato starch,or rice flour

The development of new production lines of extruded ready-to-eat (RTE) snacks often results in high losses of edible food due to the trial-and-error approach in industry. Being able to predict extrudate characteristics of new formulations before having to run trials on industrial scale would be beneficial for reducing waste and having a more efficient development process. With this study, the correlation between pasting properties of seven blends of flours/starches and extrudate characteristics was investigated (100% corn grits, 25% and 50% replacement of corn grits with high amylose starch, potato starch, and rice flour). The predictive power of pasting characteristics on extrudate's moisture content, water absorption and solubility index, sectional expansion index (SEI) and hardness was studied. Results indicated the potential of predicting SEI, water solubility index (WSI), and water absorption index (WAI) of RTE-snacks. WSI and WAI were, respectively, negatively correlated with peak temperature (R² = 0.897), and positively with peak temperature and positively with trough viscosity (R² = 0.855). One can conclude that the rheometer can be a useful tool to gain insight into the characteristics of the extrudate, although further research with enlargement of the dataset is necessary to make the rheometer effectively deployable for potentially other extrudate characteristics.     

Steady and dynamic rheological properties of thickened beverages used for dysphagia diets

Thickened beverages prepared with commercial food thickeners are widely used to promote safer and more successful swallowing in patients with dysphagia. In this study, the rheological properties of cold thickened beverages (bottled water, orange juice, apple juice, and whole milk) prepared with a commercially available gum-based food thickener (xanthan-guar gum mixture) marketed in Korea were investigated at 3 different thickener concentrations (2, 3, and 4%, w/w). Thickened beverages showed high shearthinning (n=0.12–0.21) behavior with Casson yield stress at all concentrations. Their apparent viscosity (η_a,50), consistency index (K), Casson yield stress (σ_oc), storage modulus (G′), and loss modulus (G″) increased with an increase in thickener concentration. Steady and dynamic rheological parameters also demonstrated greater differences in rheological behaviors between thickened beverages with different thickener concentrations. These results suggest that rheological properties of thickened beverages are strongly affected by thickener concentration and the type of beverage prepared.     

Moisture Adsorption Characteristics of Solar-Dehydrated Mango and Jackfruit

The moisture adsorption isotherms of solar dehydrated mango and jackfruit were determined at temperatures ranging from 30 °C to 50 °C. The equilibrium moisture content (EMC) of mango and jackfruit increased sharply as the temperature increased at water activity (a _w) above 0.6 and 0.8, respectively. However, there were no clear isothermal intersection points observed at higher a _w and temperatures. The EMC of solar dehydrated jackfruit showed the isothermal characteristics between types II and III. In contrast, dehydrated mango followed the characteristic type III adsorption isotherms due to high total soluble solids content of 67.8 °Brix and total sugars of 14.21 g/100 g fresh mango. Estimated parameters and fitting ability of three isotherm models were also evaluated. The Guggenheim-Anderson-Boer (GAB) model gave the best fit to the experimental EMC data. The GAB monolayer moisture contents (m _o) of mango and jackfruit ranged from 11.1–10.0 % and 4.7–3.4 %, respectively. Specific surface area of active binding sites (S) was calculated based on the m _o values. The S value of dehydrated mango was 2.5 to 2.8 times larger than jackfruit. The maximum net isosteric heat (q _s) of sorption of solar dehydrated mango and jackfruit were determined as 19.5 and 33 kJ mol^?1, respectively, and q _s decreased significantly at high moisture.     

Moisture‐Absorption and Water Dynamics in the Powder of Egg Albumen Peptide,Met‐Pro‐Asp‐Ala‐His‐Leu

Moisture absorbed into the powder of Met‐Pro‐Asp‐Ala‐His‐Leu (MPDAHL)—a novel egg albumen antioxidant peptide—profoundly affects its properties. In this study, we elucidated water dynamics in MPDAHL using DVS, DSC, and low‐field ¹H NMR. Based on the DVS data, we found that MPDAHL sorption kinetics obey a parallel exponential model. DSC results indicated that both water and heating could change the microstructure of MPDAHL. The T₂ parameters of NMR reflected the different phases of moisture absorption revealed that there were 4 categories of water with different states or mobility in the MPDAHL during the moisture absorption process. The fastest fraction T_2b mainly dominated the hygroscopicity of MPDAHL and the absorbed water significantly changed the proton distribution and structure of MPDAHL. Thus, this study shows that DVS, DSC, and low‐field ¹H NMR are effective methods for monitoring water mobility and distribution in synthetic peptides. It can be used to improve the quality assurance of functional peptides.     

Influence of unicellular protein on gluten-free bread characteristics

The objective of this work was to study the characteristics of three gluten-free bread formulations and the effect of the inclusion of unicellular protein. Bread recipes were starch-based, starch-vegetable-based and flour-based and the same recipes with added unicellular protein. Flour-based breads had lower specific volume values (2.2–2.3 cm³/g) than starch-based breads (3.1–3.3 cm³/g). Starch-based and starch-vegetable-based formulations with unicellular protein showed less bake loss (18.3 and 17.8%) than their counterparts (21.1 and 19.6%) probably due to increased water retention caused by unicellular protein. Flour-based recipes resulted in the firmest crumb, mainly caused by the high content in dietary fiber. The addition of unicellular protein resulted in a darker crumb color, and significant differences were also found in crumb color because of ovalbumin addition. Confocal scanning laser microscopy results showed a more compact microstructure in flour-based recipes compared with starch-based and starch-vegetable-based formulations. Starch-vegetable-based formulations without unicellular protein were the most preferred by consumers, followed by starch-vegetable-based formulations with added protein. Main differences detected by consumers were related to texture attributes. No major changes in shelf-life could be attributed to differences in formulation.     

Nano Zinc Oxide-Loaded Calcium Alginate Films with Potential Antibacterial Properties

In this work, zinc oxide nanoparticles-loaded calcium alginate films were investigated for their moisture uptake behavior at different temperatures. The equilibrium uptake data was interpreted quantitatively by GAB isotherm models. The monolayer moisture contents were 0.301 ± 0.003, 0.0214 ± 0.092, and 0.171 ± 0.102 at 20, 30, and 37°C, respectively. The water vapor transmission rate was found to be 0.816 ± 0.143, 1.42 ± 0.045, and 1.632 ± 0.064 g s⁻¹ m⁻² respectively. For the moisture content range of 0.2 to 0.6, the net ∆H and ∆S values were found to be 22.73 to 11.14 KJ/mol and 0.064 to 0.034 KJ/mol/K, respectively. The moisture uptake of films increased with water activity but showed negative temperature dependence. The enthalpy of sorption (∆H) and differential entropy (∆S) were determined at different moisture content values, ranging from 0.2 to 0.6 g/g db. The two parameters showed a higher degree of correlation. The equilibrium moisture content data was used to evaluate harmonic mean temperature T _hm. Finally, the biocidal action of films was tested against model bacteria Escherichia coli.     

增稠剂对杏鲍菇冻干粉品质的影响䥺Symbol`@@

以堆积密度、吸湿性、速溶性为指标,采用单因素、正交试验及综合加权评分法,优化3种增稠剂的组合方式,研究麦芽糊精、黄原胶、羧甲基纤维素钠添加量对杏鲍菇冻干粉品质的影响。结果表明,单独添加3种增稠剂均可改善杏鲍菇冻干粉的品质,麦芽糊精最为显著,其次为黄原胶、羧甲基纤维素钠,且在麦芽糊精15%、黄原胶0.15%、羧甲基纤维素钠0.8%的组合条件下杏鲍菇冻干粉综合品质最好。