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CLARA O. ROVEDO SUSANA E. ZORRILLA R. PAUL SINGH 《Journal of Food Processing and Preservation》1999,23(5):407-420
The change in crispness of the crust region of a fried food due to water migration was studied duringfrving and post-frying period. Moisture distribution was determined immediately after frying and at different times during storage. A restructured starch system consisting of potato starch and distilled water 16 was prepared in the shape of a patty. the moisture distribution in the patty was determined during fiying and post-frying period. Experiments were conducted for two dfferent flying times, 10 and 20 mm, using an oil temperature of 180G. Moisture distribution also was determined in patties fried for 10 mm and stored at 4C in a sealed container for 0.5, 3, and 4.5 h.
The experimental moisture profiles were compared with those obtained with a mathematical model, based on the one-dimensional heat and mass transfer in the core and crust regions of an infinite slab. Changes in the moisture content were correlated with changes in the mechanical properties of the crust during storage. 相似文献
The experimental moisture profiles were compared with those obtained with a mathematical model, based on the one-dimensional heat and mass transfer in the core and crust regions of an infinite slab. Changes in the moisture content were correlated with changes in the mechanical properties of the crust during storage. 相似文献
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MISAEL L. MIRANDA JOSÉ MIGUEL AGUILERA CAROLINA I. BERIESTAIN 《Journal of food process engineering》2005,28(3):265-281
The rupture stress (RS) of fried potato slices (1.60 mm thick) and of the crust of fried potato slabs (FPS) having lengths of 60 mm and sides of 8, 10 and 12 mm, was determined during the post‐frying period by a puncture test. The RS of fried potato slices decreased as water activity increased from 0.22 to 0.85. The RS of FPS diminished in the first 5–6 min when exposed to ambient conditions and remained almost constant thereafter. A novel videotape technique and image analysis were used to follow deflection of FPS in the post‐frying period. An apparent modulus based on the composite structure of FPS and calculated from beam mechanics decreased with time in a trend similar to that of the textural parameters. We concluded that changes in physical properties of the crust because of moisture accumulation are the major causes of loss of texture (limpness) in FPS during the post‐frying period. 相似文献
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JINTIAN FAN R. PAUL SINGH ELI J. PINTHUS 《Journal of Food Processing and Preservation》1997,21(6):443-460
Corn starch patties with an initial moisture content of 46.5% (wet basis) were fried in oil at 165C. The results indicated that oil content in the patty ranged from 10.6 to 12.5% in the crust region, and 1.5 to 3.9% in the core region. Starch gelatinization was significantly dependent on frying time and location of starch in the patty. Both, water absorption and water solubility indices of starch increased with frying time, with the starch contained in the crust exhibiting much higher water absorption ability and water solubility than that contained in the core region. Measurements of 'blue value'(the intensity of blue color of starch solution upon addition of iodide ion) and the absorbance spectra of starch samples indicated that amylose-lipid complexes were present in the fried materials. The degree of starch complexation was 10.9 to 13.2% in the crust and 0.3 to 6.6% in the core region. The puncture force on the surface of a food fried for no more than 5 min was close to that in the food center, although a significant increase in force was required for the crust region during the later stages of frying. 相似文献
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Moisture profiles in fried samples of potato starch with different gluten contents were determined during postfrying storage. Over time, moisture migrated from the core to the crust of the sample, and the moisture content of the crust region increased. The addition of gluten caused a significant increase in oil uptake in the crust. The initial hardness of the crust significantly decreased as the gluten content increased to 10 and 30%, during the first 30 min of storage. With longer storage time (> 240 min), the crust hardness tended to increase, due to an increase in firmness of the starch sample. This behavior was less pronounced for samples with 10 and 30% gluten. The range of linear viscoelastic behavior (up to 14% strain) was determined from the initial linear zone of the stress-strain curves. Stress relaxation tests were performed in the linear and nonlinear viscoelastic regions, with a strain level of 5% and 40%, respectively. According to stress relaxation curves, samples became less elastic with the addition of gluten and more elastic with the time of storage. 相似文献
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E. J. PINTHUS R. P. SINGH I. S. SAGUY J. FAN 《Journal of Food Processing and Preservation》1998,22(4):283-301
Resistant starch (RS) was determined in patties (5.1 cm diameter, 1.27 cm high) prepared by mixing starch (corn, rice, wheat, or potato) in distilled water and immersion fried in canola oil (at 170 ± 3C). The RS content (expressed as % of total starch) in corn starch increased from 4.25 to 5.43% (±0.11) in the core region of a patty, whereas in the outer crust region the RS level was constant throughout the frying process. Similar trend was observed in potato, rice, and wheat starch patties. Upon varying the amylose content in the corn starch from 21 to 70%, the initial RS content (prior to frying) increased from 3.47 to 22.74 (±0.11%), following a linear relationship. Maximum force (MF) to puncture the crust of each starch patty was determined for frying duration of 3 to 15 min. Patties exhibiting higher RS content prior to frying, developed crusts with higher MF to puncture the crust, exhibiting a linear relationship between those two variables. 相似文献
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THE EFFECTS OF FLAXSEED, SOY AND CORN FLOURS ON THE TEXTURAL AND SENSORY PROPERTIES OF A BAKERY PRODUCT 总被引:1,自引:0,他引:1
The objective of this study was to assess the effects of some healthy ingredients on the properties of a ring‐shaped bagel/pretzel‐type bakery product to offer an alternative product satisfying consumer demand. For this purpose, ground flaxseed, defatted soy flour and corn flour were blended at a weight basis with wheat flour at 5, 10 and 15%. The taste score decreased upon increasing the level of substitution of flaxseed, soy and corn flours. Samples containing 15% of flaxseed were rated poorest in taste. No significant difference was observed in crust color except 15% level of flaxseed. The control sample had highest crust color value. The crispness scores of control and other samples containing 5% corn flour were higher than that of other samples. The samples with 5% flaxseed flour had lower crust L values. Flaxseed, soy and corn flour showed significant effects on the hardness, cohesiveness, springiness, gumminess, fracture force and stiffness values (P < 0.05). Samples with 15% corn flour had the highest hardness value. The results of the present study suggest that flaxseed, soy and corn flours could be added to a typical snack formulation up to levels of 10% with a reasonable acceptance offering promising nutritious and healthy alternative to consumers. 相似文献
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J.M. REPARET F. MOINE G. ARVISENET P. LE BAIL N. CAYOT 《Journal of texture studies》2006,37(5):459-475
The effect of three different aroma compounds on the texture of starch dispersions during gelation and retrogradation was studied. Oscillatory measurements were used to follow gelation and to check the structure of the starch dispersions after retrogradation up to 28 days. Rheological tests did not indicate any effect of the presence of any of the aroma compounds on the mechanism of gelation. During long‐time retrogradation, some added aroma compound did. We assume that this is a consequence of the ability of aroma compounds to form a complex or to show another type of interaction with starch molecules like entrapment in the amorphous regions of starch. Linalool is known to form complexes with amylase, but did not induce texture modifications, probably because, in our experiments, the added amount of this compound was too low. Isoamyl acetate, which according to literature interacts with amylopectin, exhibited a weak effect after 3 or 4 weeks, depending on the amount added. Octanal also increased gel stiffness after 3 weeks. This phenomenon is consistent with the observation that this aroma compound can form complexes with starch as demonstrated by X‐ray diffraction in this study. 相似文献
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An attempt was made to measure the effect of lipid components on the viscosity and thixotropy of wheat starch paste in a short aging time after gelatinization. Viscometry was used to follow periodically the changes in apparent viscosity (at 76.8 s−1 ) of the mixed paste of wheat starch and one of a series of lipids in a cone-plate viscometer for 210 min after gelatinization, i.e. a procedure of eight cycles of measurement with a sample. Each cycle of the measurement consisted of viscometry for 3 min and a rest period for 27 min at 30°C. The apparent viscosity of all the samples decreased greatly during the 3 min measurement due to thixotropic breakdown of the macroscopic structure in the samples. The results suggest that the presence of a small amount of free fatty acid and monoglyceride may play a role in reducing starch paste gelation. 相似文献
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C-J. CHEN H-J. LIAO P.E. OKECHUKWU S. DAMODARAN M.A. RAO 《Journal of texture studies》1996,27(4):419-432
At 10% solids content, magnitudes of G' and G" of soybean 7S dispersion were substantially lower than those of corn starch dispersion, while those of soybean 11S dispersion were much higher than those of starch. Profiles of G' at 30 Hz as a function of starch concentration of starch + 7S and starch + 11S gels were asymmetrical reflecting phase separation due to thermodynamic incompatibility. However, the starch concentration corresponding to the critical point below which no phase separation occurs for the starch + 7S dispersion was about 7% and for the starch + 11S dispersion it was about 3%. At equal starch fractions, values of G' at 30 rad s-1 of corn starch + 7S dispersions were nearly equal to those of only corn starch. In contrast, at starch concentrations between 6–8%, G' values of the corn starch + 11S dispersions were much higher than those of only starch and a minimum value occurred at a starch concentration of about 5%. Based on frequency dependence of G' values, heated corn starch + 7S dispersions may be classified as weak gels, while heated corn starch + 11S dispersions may be classified as true gels. 相似文献
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The lipid constituents from wheat, corn and potato starches were analyzed, as was the composition of nonstarch compounds present in these lipid extracts. The lipids were extracted from starch granules using n- propanol-water (3:1, v/v) via cold and hot extraction into surface and internal lipid fractions, respectively; fatty acid profiles of the fractions so obtained were then carried out. The content of surface lipids was greatest from potato and wheat starches, whereas cornstarch was characterized as having the highest relative percentage of internal lipids. Hot extraction resulted in an increase in the lipid content for all extracts, and of the starches investigated, the lipids from cornstarch contained the highest percentage of polyunsaturated fatty acids. Unlike that of wheat starch, it was noted that the fatty acid, C20: 1 (n-9), could only be extracted from corn and potato starch granules by the hot extraction technique. Lysophosphatidylcholine (LPC) and some phenolics were found to bind to wheat starch granules, but not to those of corn and potato. Using HPLC-UV-DAD analysis, five phenolic compounds were detected in the lipids extracted from wheat starch by hot extraction. Maxima from UV-DAD spectra of the compounds were observed at a wavelength of 337.4 or 332.7 nm, and are characteristic of phenolic acids or their derivatives. 相似文献
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VISCOELASTIC BEHAVIOUR DURING THE GELATINIZATION OF STARCH II. EFFECTS OF EMULSIFIERS 总被引:1,自引:0,他引:1
A.-C. ELIASSON 《Journal of texture studies》1986,17(4):357-375
The viscoelastic behaviour during the gelatinization of starch in the presence of emulsifiers was studied in oscillatory shear. Glycerol-monostearate and sodium stearoyl-lactylate delayed the viscoelustic changes during gelatinization in a way which was intetpreted as related to the granules being stiffer in presence of these emulsifiers. Sodium abdecyl sulphate caused a destabilization of the granules, resulting in the rheological changes occurring at lower temperatures. Emulsifiers increased the viscous part of the rheological response. In a wary-starch variety, where the amount of amylase is small, emulsifiers had only a small effect on gelatinization. It was concluded that the formation of an amylose-lipid complex was of importance if an emulsifier was to exert an effect. 相似文献