Effect of seed treatments on the chemical composition and properties of two amaranth species: starch and protein

The seeds of two Amaranth species were studied. The starch contents were 543 and 623 g kg^?1 while crude protein contents were 154 and 169 g kg^?1 for Amaranthus caudatus and Amaranthus cruentus seeds, respectively. The effect of several treatments, including cooking, popping and germination and flour air classification on the protein and starch properties were studied. Air classification decreased the starch content and increased the protein content, while heating increased the protein but did not affect the starch content. Germination decreased both starch and protein contents. Amylose content was increased by air classification and heating, but was not affected by germination. It was found that all treatments increased the starch swelling power and reduced the falling number. The resistant starch content was increased in the high protein flour (HPF) fraction and germinated flour compared with the raw flour, while its content decreased in the heat treated seed flours. These processes also affected the starch gelatinization temperature and peak viscosity. The thermal properties of the starch flour were not affected by air classification while gelatinization energy was decreased significantly (by 52.0 and 90.0% and by 70.0 and 95.0%) in cooked and popped A caudatus and A cruentus seed flours, respectively. The gelatinization energy was highest in germinated seeds dried at 90 °C with values of 2.67 and 3.87 J g^?1. Air classification reduced the level of all protein fractions. Thermal treatment decreased the water‐soluble fraction (albumins + globulins) and alcohol‐soluble fraction (prolamins) in both species. The levels of all fractions except the water‐soluble fraction (albumins + globulins) were reduced significantly in both species by germination, which mainly increased the amount of aspartic acid, serine and alanine, while the amounts of threonine, arginine and tyrosine decreased in both species. The polypeptide bands of the HPF in both species were unchanged compared with the raw seed flours, but more intensive coloured bands were observed. Thermal treatments eliminated major and minor bands above 35.0 KDa in both species. Copyright © 2004 Society of Chemical Industry     

The resistance of packed beds of moth gram (Vigna aconitifolius) to airflow

The resistance of packed beds of clean moth gram (Vigna aconitifolius) to airflow was studied at moisture contents varying from 5.64 to 19.42% dry basis (d.b.) and at superficial air velocities ranging between 0.0104 and 0.8321 m s^?1 with bed depths of 0.2–0.6 m and bulk densities ranging from 745 to 875 kg m^?3. The airflow resistance of moth gram increased with increase in airflow rate and bulk density and decreased with moisture content. Results indicated that a 13.78% increase in moisture content decreased the pressure drop by 26.58% whereas, a 7.7% increase in bulk density increased the pressure drop by 43%. The modified Shedd's equation and Hukill and Ives equation were evaluated to see if they predicted pressure drop accurately. Airflow resistance was accurately described by the modified Shedd's equation. The statistical model that related airflow rate and bulk density could fit pressure drop data reasonably well. For loose fill beds an increase in grain moisture content increased the minimum fluidization velocity value from 1.1009 to 1.2391 m s^?1 whereas, for grain beds with 12.47% moisture content, the increase in bulk density decreased the minimum fluidization velocity value from 1.1152 to 1.0306 m s^?1.     

The Relation Between Final Popped Volume of Popcorn and Thermal-Physical Parameters

Previous studies have shown that popping volume of popcorn is affected by water content, and that popping volume increases with an increase in water content up to an optimal value, and then the volume decreases with any additional moisture. The aim of this study was to explore the mechanism responsible for the peak in popping volume as a function of water content. Popcorn was equilibrated to various water contents from 6.7 to 16.5 g/100 g d.b. over salt solutions (a_w0.33-0.82), and popped by an air popper. Maximal popping volume occurred at a water content of 15.5 g/100 g d.b. (a_w=0.745 at room temperature) while the popping temperature dropped with increasing water content. Thermal analysis of the popcorn by DSC showed no significant effect of the moisture on the melting temperature orT_g of the unpopped endosperm. However, the decrease of the pericarp melting temperature correlated with an increased water content. The results suggest that elevated water contents cause a rubbery collapse of the pericarp at lower temperature. The temperature of this melting event decreases by ∼7 °C over the 6-16.5 g/100 g moisture range. Thus, as the water content increases, the pressure in the kernel at the popping moment is lower, causing less expansion and lower final popped volume.     

Nutritional study of raw and popped seed proteins of Amaranthus caudatus L and Amaranthuscruentus L

The nutritional value of raw and popped (similar to popcorn preparation) seed proteins of two amaranth species, Amaranthus caudatus L and A cruentus L, was investigated. After popping, the true protein content in A caudatus and A cruentus decreased by 9 and 13% respectively. Among the amino acids, the loss of tyrosine due to the popping effect was the highest, followed by phenylalanine and methionine. Leucine was the first limiting amino acid in the raw samples, followed by lysine, while the reverse order was observed in the popped samples. The in vivo protein quality of raw and popped seeds was tested with male weanling rats and compared with wheat flour and casein samples. There was no difference between the in vivo digestibility of the raw and the popped seeds, although the in vitro digestibility was slightly higher for the popped samples. The protein efficiency ratio (PER) for all the amaranth seed samples was higher than that for the wheat sample, while the PER for the raw amaranth seed samples was close to that for the casein reference protein. The rat blood serum levels of total cholesterol, triglycerides and high‐density lipoprotein cholesterol for all the amaranth samples were lower than those for the reference protein, while the wheat flour sample showed the lowest values. Copyright © 2004 Society of Chemical Industry     

The effects of ingredients on popcorn popping characteristics

Response surface methodology was used to evaluate the effects of ingredients on popcorn popping characteristics. The effects of different ingredients on the expansion volume and unpopped kernel ratio of popcorn in a conventional popper and a microwave oven were evaluated and optimized by response surface methodology. The regression models were significant and had R² value in the range of 0.919–0.956. The optimum levels of ingredients for microwave popping were 4.4% salt, 5.9% vegetable oil, 0% sodium bicarbonate and 16.4% butter, this formulation giving an expansion volume of 33.1 mL g^?1. In the case of conventional popping, the maximum expansion volume of 37.3 mL g^?1 was obtained for 3.5% salt, 6% vegetable oil, 0.10% sodium bicarbonate and 12.9% butter.     

Studies on preparation,popping and functional properties of bulgur wheat

Wheat was steeped to 36% moisture and agitated for 2 min in sand heated to 170 °C. This dry heat bulgur was comparable to bulgur prepared by steam treatment. The dry heat bulgur of 14% moisture content was popped in hot (230 °C) sand medium. The expansion ratio of popped bulgur was 2.1. Some of the functional properties of popped bulgur flour were compared with native, 48 h malted and roller dried wheat flours. Water absorption index was highest for roller dried followed by popped and malted wheat, whereas water solubility index was highest for malted followed by roller dried and popped wheat. Roller dried wheat exhibited higher cold paste viscosity (360 BU) than popped (30 BU) wheat. Popped wheat had a peak viscosity of 300 BU. The viscogram of malted wheat was typical of cereal flours when the enzyme activity of malt was inhibited. The gel permeation chromatograms of popped and roller dried wheat indicated thermal degradation of starch during popping and roller drying. The in vitro carbohydrate digestibility of popped wheat was higher than roller dried and malted samples. The scanning electron microscopic examination of native and popped bulgur revealed that the endosperm of bulgur wheat was a homogenous mass containing gelatinized starch whereas that of popped bulgur was made up of thin layers of popped starch with irregular air spaces.     

Effect of amylose/amylopectin ratio and extent of processing on the physical properties of expanded maize starches

Low-density expanded starchy products are often desirable, particularly in the snack food industry. Levels of shear and amylose are often deemed crucial factors for expansion. In this study, maize starches containing low (waxy), normal and high levels of amylose were compared after processing. Low shear processing used a popping head (similar to a rice-cake machine), while high shear (~450 kJ kg⁻¹) samples (pellets and directly expanded) were created using twin-screw thermomechanical extrusion. Native starches and ground extruded materials (<106 µm) were popped using the same conditions (230 °C, 4 s, water content 12% wwb). All samples tested created fused aerated cakes, which had little or no remaining crystallinity, except for the directly popped waxy sample, which retained ~17% of its original crystallinity. Water absorbances and solubilities were influenced greatly by the starch source and marginally by the amount of processing. On processing, waxy samples showed increased solubility while those with normal amylose content had greater absorption. The densities of all the popped samples were similar despite marked differences in shear regime history and the major variations in the amylose and amylopectin ratios. These results challenge the expected relationships between shear and different starches’ potential to expand.     

Effects atmospheric radio-frequency plasma treatment on popping characteristics of popped rice and its nutritional evaluation

This study investigates the effects of household popping methods (using electric flying pans, kitchen ovens, and microwave ovens) on the popping characteristics percent yield and expansion volume (ml g^− 1)) and the nutritional value of popped rice. Next, an atmospheric RF plasma treatment (20 W and 40 W) was used to improve the yield, expansion volume, and content of essential amino acids in the popped rice. The effects of atmospheric RF plasma treatment on the surfaces of popped rice were examined using a microscope. The results demonstrated that the percent yield (42.2 ± 6.6%) and expansion volume (2.53 ± 0.72 ml g^− 1) of popped rice when using an electric flying pan were approximately 4 times higher than those observed when using a kitchen oven and approximately 3 times higher than those observed when using a microwave oven. However, the crude protein and elemental composition (P, K, Mg, Ca, Zn, Na, Mn, and Fe) of popped rice using a direct heat from an electric frying pan were found to be significantly lower than obtained using other methods. Atmospheric (RF) plasma at 40 W could improve the quality of popped rice when it is popped in an electric frying pan. Higher percent yield (53.2 ± 1.6%), expansion volume (3.59 ± 0.06 ml g^− 1), and essential amino acid content (5 mg amino acid g^− 1protein of arginine, leucine, phenylalanine, threonine, and lysine) in the popped rice were observed after plasma treatment. In addition, a microscopic investigation confirmed that large expanded pellets were observed on the surface of the plasma treated popped rice. Without plasma treatment, a smooth surface of popped rice was observed. Therefore, plasma treatment may be an important factor in the buildup of vapor pressure inside the unhusked rice. This research suggests that a combination of an electric flying pan and atmospheric RF plasma is highly effective for increasing the producing of popped rice.Industrial relevanceTreating unhusked rice with atmospheric RF plasma before popping has positive effects on yield and expansion volume of the popped rice. In addition, atmospheric RF plasma could be used to prevent loss of nutrition value during popping. This treatment also provides high production yields for the rice popping industries and benefits consumers by increasing the nutritional content of popped rice products.     

Process Optimization and Characterization of Popped Brown Rice

The popping process was optimized for brown rice based on an expansion ratio. A central composite design with interactive effect of three independent variables, including salt content (1–2.5 g/100 g raw material), moisture content (13–17 g/100 g raw material), and popping temperature (210–240°C) was used to study their effects on the expansion ratio of rice using response surface methodology. The experimental values of expansion ratio were ranged from 5.24 to 6.85. On fitting the experimental values of expansion ratio to a second order polynomial equation, a mathematical model with the predictability was developed with the statistical adequacy and validity (p ? 0.05). From the model, the optimal condition including salt content (1.75 g/100 g raw material), moisture content (15 g/100 g raw material), and popping temperature (225°C) were predicted for a maximum expansion ratio of 6.79, which was then proved to be 6.85 through experiment. Raw and popped brown rice were investigated for physical properties including hardness, L*, a*, and b* value, length/breadth ratio, bulk density, and minerals, which showed the significant differences. The optimized popped rice sample was evaluated for structural, spectroscopic, and thermal properties, which showed the significant difference from raw rice.     

Influence of Moisture Content and Temperature on Thermal Conductivity and Thermal Diffusivity of Rice Flours

The thermal conductivity and thermal diffusivity for four types of rice flours and one type of rice protein were determined at temperatures ranging from 4.8 to 36.8?°C, bulk densities 535 to 875.8 kg m^?3, and moisture contents 2.6 to 16.7% (w.b.), using a KD2 Thermal Properties Analyzer. The thermal conductivity of rice flours and rice protein increased with the increase in temperature, moisture content as well as with increase in bulk density. Thermal diffusivity decreased with increase in moisture content, increase in temperature and bulk density. The thermal conductivities values obtained were within the range of 0.045 to 0.124 W m^?1 K^?1 whereas the thermal diffusivity values were in the range of 0.094 to 0.138 mm² s^?1.     

The effect of popping,soaking, boiling and roasting processes on antinutritional factors in chickpeas and red kidney beans

This study was conducted to determine the effect that a popping head (like a rice cake machine), a low-shear and low-water processing technology, has on the concentration of antinutritional factors in chickpeas and red kidney beans. Seeds were popped under several parameters (popping time, sample format and equipment type) and analysed against soaking (1:5 w/v in reverse osmosis water for 24 h), roasting (100 g at 180 °C for 20 min) and boiling (1:5 w/v in reverse osmosis water at 100 ± 1 °C for 1 h) processes. Popping and roasting significantly reduced phytic acid content in chickpeas (6%–22%) and red kidney beans (16%–39%). In contrast, phytic acid content after soaking and boiling was not significantly different to raw seeds. Condensed tannins were significantly reduced in red kidney beans after soaking (74%), boiling (100%) and 4 s popping (28%–42%) treatments and increased in both pulses after roasting (137%) and 8 s popping (21%–47%). Further analysis showed that the soluble phenolic content increased with popping, but total and bound phenolic content was reduced. These results demonstrate that the high temperatures and pressures applied during the popping process effectively reduce antinutritional factors in pulses, compared to conventional processing methods.     

Characterization of hot air drying and microwave vacuum drying of fingerroot (Boesenbergia pandurata)

Fingerroot (Boesenbergia pandurata) was subjected to hot air drying and microwave vacuum drying. Effective moisture diffusion coefficient during the hot air drying at 60 and 70 °C were 0.2073 × 10^?10 and 0.4106 × 10^?10 m² s^?1 respectively. By using the microwave vacuum drying (13.3 kPa) at the power of 2880 and 3360 W, the effective moisture diffusion coefficient were increased to 5.7910 × 10^?10 and 6.8767 × 10^?10 m² s^?1 respectively. Based on Lewis model, drying rate constants were 0.0002, 0.0004, 0.0061 and 0.0072 s^?1 for the hot air drying at 60 and 70 °C and the microwave vacuum drying at 2880 and 3360 W respectively. Compared with the hot air drying, the microwave vacuum drying decreased drying time by 90%. Rehydration ability of the microwave vacuum dried samples was also significantly improved (P ≤ 0.05), because of porous structure. In addition, the rehydrating water of the microwave vacuum dried samples contained higher b*‐value (yellowness) than that of the hot‐air‐dried samples (P ≤ 0.05).     

Nutritional and antinutritional composition of vegetable and grain amaranth leaves

The foliage of 61 accessionso f amaranthus comparising both the grain and vegetable types referable to 10 species were evaluated for carotenoid, protein, nitrate, odxalate and moisture contents (fresh weight). Carotenoid varied from 90 to 200 mg kg^?1 in vegetable types and from 60 to 200 mg kg^?1 in the leaves of grain types. Variation for leaf protein was found to be 14-30, 15-43 g kg^?1; nitrate 1.8.-8.8, 4.1-9.2 g kg^?1; oxalate 5.1-19.2, 3-16.5 g kg^?1; and moisture 780-860, 750-840 g kg^?1 in vegetable and grain types, respectively. Analysis of the amino acid composition of leaf protein of some high carotenoid lines revealed a well balanced composition with high lysine (40-56 g kg^?1). variation of all the five parameters (carotenoid, protein, nitrate, oxalate and moisture) with respect tot he leaf position in vegetable type (4- and 8-week-old plants) and with respect to age (- to 4-month-old plants) in grain types was also studied.     

Wet‐fractionation of Phaseolus lunatus seeds: partial characterization of starch and protein

The optimum extraction conditions for integral use of Phaseolus lunatus seed, in alkaline medium, are 1:6 (w/v) flour:water ratio, pH 11 and a 1 h extraction time. Three main fractions were produced under these conditions: starch; protein isolate and fibrous residue by‐product. The yield is 288.4 g kg^?1 starch, 188.2 g kg^?1 protein isolate and the remaining quantity, fibrous residue. The starch has 98.4% purity, a 75 °C gelatinization temperature and high syneresis even at high concentrations. It also has high viscosity, good stability and middle retrogradation during the heating–cooling cycle. The protein isolate contains 711.3 g kg^?1 protein as well as 75.5 g lysine kg^?1 protein, 10.1 g methionine kg^?1 protein and 12.2 g tryptophan kg^?1 protein. Its in vitro digestibility is 79% with a 2.5 c‐PER. The fibrous residue contains 63 g kg^?1 of protein, 328.4 g kg^?1 of crude fiber and 567.3 g kg^?1 of NFE. Copyright © 2004 Society of Chemical Industry     

Physical evaluation of popped cereal snacks with spent hen meat

Various blends of spent hen meat and grains (potato starch, corn starch, and rice flour) were popped using a popping machine. Lowest bulk density was observed in the snack with 1:2 ratio of meat and potato starch. Except for the popped snack with meat and rice flour, as the starch content increased, bulk density decreased gradually. Popped snacks with grains only were higher in L* value than those with meat and grains. The a* and b* values increased with increasing meat content. All popped snacks were significantly different (P<0.001) in bulk density, color, and breaking force. As the grain content of snacks increased, the size of the air cells also increased. Results of scanning electron microscopic and optical microscopic observations revealed the popping degree of snack with starch and spent hen meat was affected by the presence of meat. The optimum ratios of meat to grain for high expansion ratio were determined to be 1:2 and 1:3 of meat to corn starch and potato starch.     

ESTIMATION OF MOISTURE LOSS FROM THE COOLING DATA OF POTATOES

A procedure was developed to predict moisture loss from cooling data of potato packed in gunny bags and stacked on wooden platforms in commercial cold stores. To predict the moisture loss, mass transfer coefficients k_cand k_mwere estimated during the storage period, which were found to decrease with time. The calculated time average k_cand k_mvalues were 1.83 × 10^?4 m/s and 2.31 × 10^?10 kg/s·m²·Pa during the transient cooling period and 1.59 × 10^?4 m/s and 2.27 × 10^?10 kg/s·m²·Pa for the rest of the storage period, respectively. The estimated moisture losses were 4.8, 4.74 and 4.78%, at the center of three different stacks, for a storage period of 8 months. The corresponding experimentally measured weight losses at the center of the same stacks were 5.2, 5.1 and 5.26% with a variation of 11, 7.5 and 10.2%, respectively. Therefore, the procedure adopted in this study may be used to assess the moisture loss from potatoes under the different storage conditions. The effect of relative humidity (RH) and potato temperature on moisture loss was also predicted using the developed procedure. Decrease in RH of the storage air increased the moisture loss. The potatoes stored below 85% RH incurred more than 7% water loss. Therefore, 88–90% RH in the cold store may be used to limit the maximum moisture loss within the permissible limit of 5% even after 8 months of storage. It was also found that increasing the potato temperature exponentially increased the rate of moisture loss.     

Seed treatments affect functional and antinutritional properties of amaranth flours

The effects of seed treatments, including cooking, popping germination and flour air classification, on the functional properties and antinutritional factors of Amaranthus caudatus and Amaranthus cruentus seeds were studied. Thermal treatments increased the water absorption with a maximum value of 5.1 and 6.3 g g⁻¹ in flour of popped seeds of both species. Generally, fat absorption increased after the treatments. Air classification and germination followed by drying at low temperature increased the foam stability of the flours, while thermal treatment and germination followed by drying at higher temperatures reduced the foam stability. All treatments except air classification decreased the emulsion stability. Also, all treatments except germination followed by drying at 30 °C increased the flour dispersibility, whereas the soluble nitrogen index was increased in the germinated seed flours and decreased in thermal treated seeds and air‐classified flours. Air classification increased the contents of phenolic compounds and phytate and decreased the contents of enzyme inhibitors, whereas the thermal treatments reduced the contents of phenolic compounds, phytate and enzyme inhibitors to a greater extent for cooking than for popping. Germination followed by drying reduced the level of phenolic compounds, phytate and enzyme inhibitors. Copyright © 2006 Society of Chemical Industry     

Influence of seed mycoflora and harvesting conditions on milling,popping and malting qualities of sorghum (Sorghum bicolor)

Four cultivars of sorghum were artificially inoculated with Fusarium moniliforme conidia at flowering and bagged. These samples along with their untreated controls were harvested at physiological maturity and 2 weeks after physiological maturity. The grains obtained from both the treatments were studied for their milling, malting and popping characteristics. Grains harvested at physiological maturity stage possessed superior milling and malting characteristics whereas late-harvested grains exhibited better popping characteristics. Milling and popping reduced the seed mycoflora considerably.     

Mass transfer evaluation of ultrasonic osmotic dehydration of cherry tomatoes in sucrose and salt solutions

In order to elaborate dehydration and osmotic equilibrium characteristics of cherry tomatoes and to analyse the applicability of Peleg model in prediction of equilibrium moisture content and the methodology of Crank’s solution to Fick’s diffusion law in calculation of effective diffusivity, cherry tomatoes were osmotically treated in ternary solution (water, sucrose and NaCl) with or without ultrasound at 30 °C. Results indicated that, a time cumulative effect of ultrasound occurred about 30 min for water loss (WL), while for sugar gain it happened after 45 min, which made the dehydration efficiency index best at the ultrasonic power of 150 W for 40 min. As a function of salt content, the equilibrium WL followed well the first order exponential decay model, and the equilibrium salt content followed well the second order polynomial. A great relative error (29.13%) between the practical determination and the predicted value indicated that Peleg model was not suitable for prediction of equilibrium moisture content. A great truncation error (865%) occurred when moisture effective diffusivity (6.66 × 10^?9 m² s^?1) was calculated with Crank’s solution to Fick’s diffusion law by letting n = 1 as compared to that (0.77 × 10^?9 m² s^?1) by letting n = 100.     

Protein quality and amino acid-protein relationships of maize,sorghum and rice grain as influenced by nitrogen,phosphorus, potassium and soil moisture stress

In pot and field experiments cereals were grown with greatly differing rates of N, P and K applications. For maize and sorghum, soil moisture levels were also varied. N applications, P- and K-deficiency, and moisture stress generally increased the total N content of grain, from 1.06 to 2.68, 1.01 to 2.42 and 0.81 to 2.33% (as % of DM) for maize, sorghum and rice, respectively. P, K and moisture stress affected the amino acid composition only indirectly through their effects on N concentration. In all three cereals increasing N concentrations were associated with decreases in crude protein of lysine, methionine, cystine, threonine, tryptophan and, generally, with increases of isoleucine, leucine, phenylalanine and glutamate. Lysine as a percentage of dry matter increased up to the highest N concentration in all three cereals. Linear regressions with significant correlation coefficients were found between concentrations of most (g 16 g^?1 N) or all (mg 100 g^?1 DM) amino acids and N content of grain. Based on all experimental data equations for lysine were: g 16 g^?1 N=4.44–0.89 × %N; 4.23–0.86 × % N; 4.39–0.42 × % N for maize, sorghum and rice, respectively. Correction of P- and K-deficiency decreased N content of grain and resulted in higher lysine content and better nutritional value of grain protein, whereas correction of N-deficiency had the opposite effect. The amino acid composition of rice was much more balanced than that of maize and sorghum with a leucine/isoleucine ratio of 2 compared to that of 3 in maize and sorghum. In rat feeding experiments true digestibility of maize and sorghum protein was high (about 95%) but increased only slightly with increasing N in grain, whereas the biological value decreased considerably, from 63 to 55 and from 70 to 58, respectively. The chemical score underestimated the nutritional value of both cereal proteins.