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1.
The objective of this work was to study the effect of addition of milk protein concentrate (MPC, 0–10%) and feed moisture (FM, 20–30%) in a blend of corn starch (CS, 80%) and quality protein maize (QPM, 20%) on different physicochemical characteristics of third‐generation (3G) snack foods using extrusion technology. A laboratory single‐extruder with a 3:1 compression ratio, a rectangular die, and a central composite nonroutable model with two variables were used. The physicochemical characteristics evaluated were expansion index (EI), bulk density (BD), penetration force (PF), and color parameters L*a*b*. EI decreased with the increase of MPC and FM, whereas BD and color parameters (a* and b*) increased; PF showed a minimum point (MPC = 5% and FM = 25%). EI, BD, and PF were selected for the optimization process in an area of superposition of 1.5–4.1% of MPC and 20.0–24.1% of FM. A validation of the optimal area was performed on samples with average values of 4.64 (±0.28) for EI, 141.02 (±7.29) kg m–3 for BD, and 0.0033 (±0.00065) for N m PF. It is feasible to obtain a functional 3G snack food with good expansion characteristics using a microwave oven, and this snack has health benefits due to the addition of MPC and QPM.  相似文献   

2.
The aim of this work was to study the effects of extrusion barrel temperature (70–180°C), feed moisture (18–30%), pH (3–8), different proportions of corn starch (75–95%), and whey protein concentrate (WPC, 80% protein concentration) (25–5%) on the preparation of functional blends. Expansion index (EI), bulk density (BD), compression force (CF), color, water absorption index (WAI), water solubility index (WSI), gel strength (GS), syneresis of the gel, and in vitro digestibility were evaluated. Barrel temperature and the proportion of WPC had significant effects on BD; at higher temperatures, BD was lower. Feed moisture and pH had significant effects on EI; with lower moisture and higher pH, the EI increased. An interaction of barrel temperature and feed moisture had an effect on WAI; at lower moisture content, the temperature effect was nonexistent, whereas at higher temperatures and feed moisture content, the WAI increased. The pH level had a significant effect on WSI, showing high WSI when lower pH levels were used. Color analysis showed that higher protein content and pH generated higher δE values; low feed moisture and low pH resulted in gel syneresis. Higher in vitro digestibility was obtained when a higher WPC proportion and pH were used. Extruded WPC-CS blends under alkaline and acidic conditions were affected by the preparation of diverse formulations that potentially can be used in foods to improve some functional and protein content.  相似文献   

3.
The aim of this work was to study the effects of barrel temperature (BT, 93.5–140.5°C), feed moisture (FM, 21.3–34.7%), and winter squash flour content (SFC, 0.43–15.6%) on physicochemical properties of microwave‐expanded third‐generation snack foods obtained by extrusion. Physicochemical properties used for optimization were expansion index (EI), penetration force (PF), specific mechanical energy (SME), and total color difference (ΔE). Response surface methodology was used for the analysis of data. The highest values of EI and lowest values of PF were found at high BT and low FM. The lowest values of SME were obtained at high levels of FM throughout the range of BT and SFC, whereas the highest values of ΔE were obtained at high SFC and low FM. Increasing levels of SFC increased ΔE values, whereas EI and SME values decreased. The best processing conditions (EI > 6.0, PF < 9.5 N, SME < 172 kJ/kg, and ΔE < 18) were found in the range of BT, 122–141°C; FM, 24.7–29.5%; and SFC, 0–10.9%. Under optimal process conditions, the retention of total carotenoids was higher than 60%. It is possible to manufacture third‐generation snack foods with good physicochemical properties, which could bring a health benefit because of the presence of carotenoids and dietary fiber in winter squash flour.  相似文献   

4.
Extrusion with CO2 injection was developed to simplify the process of producing vacuum‐puffed yukwa (rice snacks). The effects of feed moisture content and CO2 injection on the characteristics of extruded pellets (maximum viscosity and degree of gelatinization) and vacuum‐puffed yukwa (expansion ratio, bulk density, hardness, and color) were investigated. Higher feed moisture increased the size of vacuum‐puffed yukwa and the degree of gelatinization, whereas the maximum viscosity decreased. Maximum viscosity and gelatinization degree of extruded pellets were highly correlated with expansion ratio, bulk density, hardness, and color values of vacuum‐puffed yukwa. Increasing feed moisture content significantly increased expansion ratio but decreased bulk density and hardness. CO2 injection decreased bulk density and hardness of vacuum‐puffed yukwa.  相似文献   

5.
In various Latin American countries, large volumes of potato are classified as unsuitable for use as food and destined for use as feed. This raw material has a high starch and fiber content that could be used in the production of different kinds of food. The objective of this research was the preparation and characterization of extruded whole potato pellets expanded by microwave heating. A 33 central composite routable experimental design and response surface methodology were used. The barrel temperature (BT, 93–127°C), feed moisture (FM, 19–29%), and corn starch concentration (CS, 3–37%) in the blends were evaluated. CS was the most important variable affecting the functional properties of the expanded pellets. Adding CS to the blends increased the expansion index and viscosity and improved luminosity, decreasing the apparent density and breaking force of the products. Low BT and especially high FM increased the luminosity of the expanded pellets. Increasing FM content increased the viscosity of the expanded pellets. The best functional characteristics for the expanded pellets were obtained using a blend of 63% potato flour and 37% CS, extruded at 110°C BT with 24% FM content. Nonfood-grade whole potato flour showed good potential for use in the production of expanded pellets with acceptable functional properties.  相似文献   

6.
An in‐line slit‐die viscometer (SDV) was used to measure the viscosity of a melt extrudate independently of the extruder operating conditions. The melt produced by extrusion of the corn grits followed a power law rheological model. The viscosity of the melt and extrusion parameters such as specific mechanical energy (SME), torque, and die pressure decreased with increasing moisture content. The degree of starch gelatinization increased when barrel temperature increased from 90 to 130°C. At temperatures higher than 130°C, most of the starch had gelatinized. The increase in barrel temperature, however, resulted in small changes in the apparent viscosity of the melt, until a maximum of ≈130°C. At a constant feed rate, SME increased and torque decreased when screw speed increased due to the shear thinning behavior of the melt. At a constant screw speed, the torque increased and SME decreased with increasing feed rate. This was due to a decrease in apparent viscosity of the melt at higher feed rates. SME is not an independent extrusion variable and should be used with caution either when predicting the effect of thermomechanical treatment of the product or as the key and only variable for controlling the food extrusion process.  相似文献   

7.
Wheat flour with 0.3% (w/w) thiamin was extruded on a twin‐screw laboratory‐scale extruder (19‐mm barrel) at lower temperatures and expanded using carbon dioxide (CO2) gas at 150 psi. Extrusion conditions were die temperature of 80°C and screw speed range of 300–400 rpm. Control samples were extruded at a die temperature of 150°C and screw speed range of 200–300 rpm. Dough moisture content was 22% in control samples and 22 and 25% in CO2 samples. Expansion ratio, bulk density, WAI, and %WSI were compared between control and treatment. CO2 injection did not significantly increase expansion ratio. Bulk densities in the CO2 extruded samples decreased when feed moisture decreased from 25 to 22%. The products using CO2 had lower WAI values than products puffed without CO2 at higher temperatures. The mean residence time was longer in CO2 screw configurations than in conventional screw configurations. Thiamin losses were 10–16% in the control samples. With CO2, thiamin losses were 3–11% at 22% feed moisture, compared with losses of 24–34% at 25% moisture. Unlike typical high‐temperature extrusion, thiamin loss in the low‐temperature samples decreased with increasing screw speed. Results indicate that thiamin loss at lower extrusion temperatures with CO2 injection is highly dependent on moisture content.  相似文献   

8.
Extruded pellets were prepared from normal corn starch using a corotating twin‐screw extruder (25:1 L/D ratio, 31 mm diameter screw), and then expanded by heating in a conventional microwave oven for 70 sec. The effects of gelatinization level and moisture content of the extruded pellets on the morphology and physical properties of the microwave‐expanded products such as puffing efficiency, expansion bulk volume, and bulk density were investigated. The expanded shape and air cell structure differed according to the degree of gelatinization of the pellets. Maximum puffing efficiency and expansion volume with the pellets containing 11% moisture were achieved at 52% gelatinization. For this level of gelatinization, starch was extruded at 90°C barrel temperature. In addition, the moisture content of the pellets critically affected the expansion behavior. The maximum puffing efficiency and expansion volume were achieved in a moisture range of 10~13%. For optimum product shape and uniform air cell distribution, the pellets should undergo sudden release of the superheated vapor during the microwave‐heating. The expansion by microwave‐heating was optimized at ≈50% gelatinization.  相似文献   

9.
This study was conducted to develop a ready‐to‐eat extruded food using a single‐screw laboratory extruder. Blends of Indian barley and rice were used as the ingredients for extrusion. The effect of extrusion variables and barley‐to‐rice ratio on properties like expansion ratio, bulk density, water absorption index, hardness, β‐glucan, L*, a*, b* values, and pasting characteristics of extruded products were studied. A central composite rotatable design was used to evaluate the effects of operating variables: die temperature (150–200°C), initial feed moisture content (20–40%), screw speed (90–110 rpm), and barley flour (10–30%) on properties like expansion ratio, bulk density, water absorption index (WAI), hardness, β‐glucan, L*, a*, b* values, and sensory and pasting characteristics of extruded products. Die temperature >175°C and feed moisture <30% resulted in a steep increase in expansion ratio and a decrease in bulk density. Barley flour content of 10% and feed moisture content of <20% resulted in an increased hardness value. When barley flour content was 30–40% and feed moisture content was <20%, a steep increase in the WAI was noticed. Viscosity values of extruded products were far less than those of corresponding unprocessed counterparts as evaluated. Rapid visco analysis indicated that the extruded blend starches were partially pregelatinized as a result of the extrusion process. Sensory scores indicated that barley flour content at 20%, feed moisture content at 30%, and die temperature at 175°C resulted in an acceptable product. The prepared product was roasted in oil using a particular spice mix and its sensory and nutritional properties were studied.  相似文献   

10.
Sorghum (Sorghum bicolor (L.) Moench) grain was boiled or autoclaved in alkali, washed, drained, and dried into shelf-stable half-products (pellets). The pellets were deep-fat fried to produce a crunchy snack product. Effects of cooking time, drying method (pellet moisture content), and sorghum cultivar on unfried and fried pellets were evaluated. Increasing the alkaline cooking time from 30 to 60 min decreased the yield of the pellets from 96 to 84% (on a dry weight basis). Cooked sorghum dried at room temperature (24°C) for 18 hr, followed by oven-drying at 50°C for an additional 18 hr, produced pellets with a low moisture content (≤5%), that required a higher frying temperature (≥220°C). However, cooked sorghum dried at room temperature for 18 hr followed by oven-drying at 50°C for 5 hr produced pellets with 9% moisture and a lighterdensity highly acceptable product when fried at 220°C. Fat content of fried pellets averaged 18%. The optimum method for producing a light, crunchy, fried product was cooking for 60 min, drying to 9% moisture, and frying at 220°C. ATx631*Tx436, the hardest endosperm-texture sorghum used in the study, had the highest unfried and fried pellet yields. Dorado, an intermediate-to-soft endosperm-texture sorghum, and ATx Arg-1*Tx2907, a waxy sorghum, had lower yields. The fried pellets produced from Dorado and waxy sorghum (ATxArg-1*Tx2907) were more expanded than those produced from ATx631*Tx436.  相似文献   

11.
A series of cross‐linked hydroxypropylated corn starches were extruded with a Leistritz micro‐18 co‐rotating extruder. Extrusion process variables including moisture (30, 35, and 40%), barrel temperature (60, 80, and 100°C), and screw design (low, medium, and high shear) were investigated. Scanning electron microscopy (SEM) of extruded starches showed a gel phase with distorted granules and granule fragments after extrusion at 60°C. After extrusion at 100°C only a gel phase was observed with no granular structures remaining. High performance size exclusion chromatography (HPSEC) equipped with multiangle laser light‐scattering (MALLS) and refractive index (RI) detectors showed extruded starches degraded to different extents, depending on extrusion conditions. The average molecular weight of the amylopectin of unextruded native corn starch was 7.7 × 108. Extrusion at 30% moisture, 100°C, and high shear reduced the molecular weight of amylopectin to 1.0 × 108. Hydroxypropylated normal corn starch extruded at identical conditions showed greater decreases in amylopectin molecular weight. With the addition of cross‐linking, the amylopectin fractions of the extruded starches were less degraded than those of their native and hydroxypropylated corn starch counterparts. Similarly, increasing moisture content during extrusion lowered amylopectin degradation in the extruded starches. Increasing temperature during extrusion of cross‐linked hydroxypropylated starches at high moisture content (e.g., 40%) lowered amylopectin molecular weights of the extruded starches, whereas increasing extrusion temperature at low moisture content (30%) resulted in less degraded molecules. This difference was attributed to the higher glass transition temperatures of the cross‐linked starches.  相似文献   

12.
The effects of added calcium hydroxide (0.0, 0.15, 0.25, and 0.35%) and processing conditions, feed moisture content (mc) (16, 18, and 20%) and barrel temperature (130 and 150°C) on characteristics of corn meal extrudates were studied. Extruder screw speed was maintained at 130 rpm. Corn meal was extruded with a single-screw extruder (Brabender model GNF 1014/2) with a screw compression ratio of 3:1. The highest values (P < 0.05) for radial expansion and the lowest values for density and breaking force of extrudates were found for the treatment with 0.00% calcium hydroxide extruded at 16% feed mc and 130°C barrel temperature. This treatment was statistically different from the other treatments. Best values for radial expansion of samples extruded with added calcium hydroxide were for the samples with 0.15% calcium hydroxide at 18% feed mc and 130°C barrel temperature, followed by the sample with 0.35% calcium hydroxide at 16% feed mc and 130°C barrel temperature. Water absorption index and water solubility index were affected by calcium hydroxide and extrusion conditions evaluated. Extrudates had large numbers of flattened and sheared granules. Increases in calcium hydroxide increased extrudate yellowness. The combined action of calcium hydroxide and extrusion conditions completely modified the organized structure of the starch and suggest the formation of a starch-calcium complex (crystalline region). The texture of the extruded products was crispy after puffing.  相似文献   

13.
Resistant starches (RS) were prepared from wheat starch and lintnerized wheat starch by autoclaving and cooling and by cross‐linking. Heat‐moisture treatment also was used on one sample to increase RS. The experimental resistant starches made from wheat starch contained 10–73% RS measured as Prosky dietary fiber, whereas two commercial resistant starches, Novelose 240 and 330, produced from high‐amylose maize starch, contained 58 and 40%, respectively. At 25°C in excess water, the experimental RS starches, except for the cross‐linked wheat starch, gained 3–6 times more water than the commercial RS starches, and at 95°C gained 2–4 times more. Cross‐linked RS4 wheat starch and Novelose 240 showed 95°C swelling powers and solubilities of 2 g/g and 1%, and 3 g/g and 2%, respectively. All starches showed similar water vapor sorption and desorption isotherms at 25°C and water activities (aw) < 0.8. At aw 0.84–0.97, the resistant starches made from wheat starch, except the cross‐linked wheat starch, showed ≈10% higher water sorption than the commercial resistant starches.  相似文献   

14.
Corn distillers dried grains (DDGS) were compacted into cylindrical pellets (3.5 cm in length, 1.5 cm in diameter) utilizing a closed‐end die under axial stress from a vertical piston applied by an Instron universal testing machine. The effects of independent variables, including the raw material moisture content (25–35% db), processing temperature (100–120°C), pressure (12.5–37.5 MPa), and dwell time (5–15 sec) on pellet density, durability, and stability were determined using response surface methodology. Moisture content, temperature, and pressure significantly affected (P < 0.05) the properties of DDGS pellets, while the influence of dwell time was negligible (P > 0.05). Increasing temperature initially increased and then decreased unit density. High moisture and pressure had favorable effects on unit density and durability rating. The density ratio increased with increasing pressure and moisture content. The results suggested technical feasibility of compacting DDGS. For the range of variables tested, optimum levels were identified as 34.6% moisture content, 107°C press temperature, and 36.8 MPa pressure to obtain maximum durability and density and acceptable dimensional stability.  相似文献   

15.
One of the fastest growing industries in the United States is the fuel ethanol industry. In terms of ethanol production capability, the industry has grown by more than 600% since the year 2000. The major coproducts from corn‐based ethanol include distillers dried grains with solubles (DDGS) and carbon dioxide. DDGS is used as a livestock feed because it contains high quantities of protein, fiber, amino acids, and other nutrients. The goal of this study was to quantify various chemical and physical properties of DDGS, distillers wet grains (DWG), and distillers dried grain (DDG) from several plants in South Dakota. Chemical properties of the DDGS included crude ash (5.0–21.93%), neutral detergent fiber (NDF) (26.32–43.50%), acid detergent fiber (ADF) (10.82–20.05%), crude fiber (CF) (8.14–12.82%), crude protein (27.4–31.7%), crude fat (7.4–11.6%), and total starch (9.19–14.04%). Physical properties of the DDGS included moisture content (3.54–8.21%), Aw (0.42–0.53), bulk density (467.7–509.38 kg/m3), thermal conductivity (0.05–0.07 W/m·°C), thermal diffusivity (0.1–0.17 mm2/sec), color L* (36.56–50.17), a* (5.2–10.79), b* (12.53–23.36), and angle of repose (25.7–47.04°). These properties were also determined for DWG and DDG. We also conducted image analysis and size determination of the DDGS particles. Carbon group characterization in the DDGS and DDG samples were determined using NMR spectroscopy; O‐alkyl comprised >50% of all DDGS samples. Results from this study showed several possibilities for using DDGS in applications other than animal feed. Possibilities include harvesting residual sugars, producing additional ethanol, producing value‐added compounds, using as food‐grade additives, or even using as inert fillers for biocomposites.  相似文献   

16.
Rapid drying with high‐temperature air has gained interest in the rice industry, but the effects of elevated‐temperature exposure on physicochemical properties of rice are of concern. This study investigated the effects of exposing rough rice to elevated temperatures for various durations without removing moisture. Physicochemical property response was evaluated in terms of head rice yield (HRY), germination rate (GR), milled‐rice yellowing, pasting properties, and gelatinization temperatures. Two long‐grain cultivars (pure‐line Wells and hybrid CL XL729) at initial moisture contents (IMCs) of 17.9 and 18.6%, respectively, and dried moisture content (DMC) of 12.5%, were hermetically sealed and exposed to 40, 60, and 80°C for various durations. Exposure to 80°C of IMC samples of Wells and CL XL729 resulted in a significant (2.3–2.5 percentage point) reduction in the HRYs. A 2 hr exposure of both cultivars at IMC level to 60°C completely inhibited GR, and exposure to 80°C of the cultivars at both moisture content (MC) levels immediately inhibited GR. Exposure to 80°C for almost all durations and 60°C for durations over 4 hr produced significant yellowing in both cultivars at IMC. Significant yellowing in both cultivars at DMC was also observed during a 28 day storage following 80°C exposure. In general, peak viscosities of both cultivars at IMC increased only after extended exposure to 40 and 60°C, but peak viscosities of the cultivars exposed to 80°C increased sharply and immediately upon exposure. No significant differences were observed in gelatinization temperatures of either cultivar at either MC level from elevated‐temperature exposure. Results from this study suggest that extreme‐temperature exposure of rough rice affects HRY, GRs, yellowing, and pasting properties of rice, but the extent of impact is MC dependent.  相似文献   

17.
Third‐generation snacks obtained by microwave expansion of glassy cereal pellets are often hard and nonuniform and need to be improved to become acceptable to the consumer. Gums such as carboxymethyl cellulose (CMC) and xanthan gum (XG) have the ability to improve the volume, structure, and texture of expanded cereal products, due to their effects on moisture retention and rheological properties. This study investigates the effect of 1% addition of CMC and XG on the structural and mechanical properties of samples obtained by microwave expansion of glassy corn pellets. Unexpanded, glassy pellets were obtained by extrusion and subsequent equilibration at aw = 0.53 at room temperature. The equilibrated pellets were expanded by microwave heating. The addition of gums significantly improved the shape, structural and textural uniformity of the microwave‐expanded samples. These effects were attributed to the contribution of gums to the rheology and moisture sorption capacity of the matrix. It is our hypothesis that the extended hydrocolloid macromolecules interpenetrated the polymeric starch matrix and created a fine network of “holes” distributed relatively uniformly in the matrix, which served as additional nucleation sites for expansion. The conclusions of this study can be used in the design of high‐quality, fat‐free, third‐generation snacks.  相似文献   

18.
Nonwaxy rice starch was cross‐linked with sodium trimetaphosphate and sodium tripolyphosphate to obtain different degrees of cross‐linking (9.2, 26.2, and 29.2%). The objective was to investigate the influence of cross‐linking on thermal transitions of rice starch. Starch suspensions (67% moisture) were heated at 2°C/min using differential scanning calorimetry (DSC) to follow melting transition of amylopectin. Biphasic transitions were observed at ≈60–95°C in all samples. Melting endotherms of amylopectin shifted to a higher temperature (≤5°C) with an increasing degree of cross‐linking, while there was no dramatic change in enthalpy. Recrystallization during aging for 0–15 days was significantly suppressed by cross‐linking. The delayed gelatinization and retrogradation in crosslinked starch were evident due to restricted swelling and reduced hydration in starch granules. Glass transition temperature (Tg) measured from the derivative curve of heat flow was ‐3 to ‐4°C. No significant change in Tg was observed over the storage time studied.  相似文献   

19.
The effects of moisture, screw speed, and barrel temperature on pasting behavior of refabricated rice grains were investigated in a corotating twin‐screw extruder with response surface methodology. The rice flour obtained from broken rice (≤1/8 of actual kernel size) of PR‐116 variety was used in the study. The screw speed was set at five levels between 49 and 150 rpm, barrel temperature between 59 and 110°C, and feed moisture between 31 and 45%. All pasting properties of refabricated grains evaluated—peak viscosity, hold viscosity, breakdown viscosity, final viscosity, and setback viscosity—were significantly (P < 0.01) affected by the three process variables. Barrel temperature was the most significant variable, with quadratic effect on all viscosity parameters. Response surface regression models were established to correlate the viscosity profile of refabricated rice grains to the process variables. The optimum moisture content, screw speed, and barrel temperature estimated by a response surface of desirability function for the production of refabricated rice were 36%, 130 rpm, and 89.5°C, respectively. Scanning electron microscopy also revealed that intermediate moisture and temperature along with high screw speed during extrusion could create a more realistic appearance of refabricated rice with less rupture of starch granules.  相似文献   

20.
《Cereal Chemistry》2017,94(1):124-127
Two gluten‐free snacks containing chickpea, plantain, and maize flours at different concentrations were prepared. The impact of chickpea or plantain flour level on weight gain, insulin resistance, and serum lipid profile of rats fed a high‐fructose diet was evaluated. A dose of 0.93 g/kg was used in the experiments to simulate the snack consumption level by humans (average content of a small package, which is twice the portion recommended by the U.S. Department of Agriculture). Compared with a high‐fructose reference diet, consumption of both snacks decreased weight gain, fasting serum glucose, and triglycerides. The effect was more pronounced for snack B, with higher chickpea content. Consumption of these snacks may also have beneficial effects against obesity and cardiometabolic complications. Chickpea flour is a promising functional ingredient for the development of antiobesity foods.  相似文献   

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