No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Dynamics of Crust Formation and Kinetics of Quality Changes During Frying of Meatballs
Abstract
Mathematical models describing dynamics of crust formation and kinetics of crust color and firmness changes were developed for the deep-fat frying of beef meatballs. Good agreement (R2 ranged between 0.815 and 0.987) was observed between experimental and predicted data. Crust color lightness, redness, and yellowness decreased exponentially with frying time while total color change increased. All color parameters followed first order reaction kinetics. Meatball firmness was measured by peak force obtained from a puncture test whose kinetics model had a reaction rate constant of 5.39E-3 1/(s.Nn-1) and a reaction order of 0.0013.
... Frying is one of the common cooking methods for meatballs. Ateba and Mittal [15] investigated the process of coat evolution and attributes of meatballs suffering from frying. Wang et al. [16] found that ultrasonic-aided frying could improve some physicochemical indexes of beefballs. ...
... Zhang et al. [17] further proved that ultrasonic-aided frying could improve the flavor profiles of meatballs. After frying, meatballs are deodorized and endowed with aroma, maintaining a better appearance by denaturing meat protein and solidifying at high temperature [14,15,18]. However, high calorie and oil content of fried food make consumers anxious about chronic cardiovascular disease [18][19][20]. ...
... e three groups of samples showed different HS-GC-IMS characteristic flavor profiles, and the concentrations of flavor substances in different fried samples increased or decreased and relatively obvious differences are shown in the yellow dotted box (Figure 2(b)). e characteristic spectrum of samples with different frying methods exhibited certain differences, probably due to the variation in heat and mass transfer, crust formation, nonenzymatic browning extent, and other factors during frying [15,19,20,24]. ...
Effects of deep fat frying and hot air frying on texture, color difference, sensory score, yield, fat content, and volatile flavor compounds of giant salamander meatballs before and after frying were investigated. Te results showed that, compared with the
deep fat frying group, hot air-fried giant salamander meatballs had higher hardness, elasticity, and L∗ (p < 0.05), but lower a∗, b∗ value, fat content, and yield (p < 0.05). Tere was little distinction in sensory score, cohesiveness, and chewiness between the two
frying methods (p > 0.05). Gas chromatography ion migration chromatography (GC-IMS) was used for flavor compound analysis, and 50 flavor compounds were analyzed, containing 22 aldehydes, 11 ketones, 6 olefins, 4 acids, 3 esters, 3 alcohols, and 1
phenol. Compared with the samples before frying, the relative contents of aldehydes and ketones of fried giant salamander meatballs increased significantly, while the relative contents of esters and alkenes decreased significantly. Principal component
analysis showed that the GC-IMS spectra of volatile flavor compounds before and after deep fat frying and hot air frying varied greatly, and the cumulative contribution rate of the two principal components reached 86.1%, indicating that the GC-IMS technology might be used to distinguish giant salamander meatballs before and after frying, or with different frying methods.These results may offer a note for development and quality control of the precooked giant salamander meatballs in the future.
... The study and modeling of the kinetics of changes in some important physical properties in potatoes during frying has been made by some researchers (Gupta, Shivhare, and Bawa 2000; Krokida et al. 2001b; Moyano and Berna 2002; Moyano, Rioseco, and Gonzaléz 2002; Moyano and Pedreschi 2006; Pedreschi, Aguilera, and Pyle 2001; Sahin 2000). However, there are studies in many other products such as meatballs, tofu, tortilla chips, chicken nuggets, pork meat and donuts (Ateba and Mittal 1994; Baik and Mittal 2003; Moreira, Sun, and Chen 1997; Ngadi, Li, and Oluka 2007; Sosa-Morales, Orzuna-Espíritu, and Vélez-Ruiz 2006; Vélez-Ruiz and Sosa-Morales 2003 ). Researchers have expressed the variation of quality during frying using empirical models (57%) or theoretical kinetic models (43%) (Hindra and Baik 2006). ...
... To obtain the specifi c reaction rate of color change, k, the approach used by Ateba and Mittal (1994) is utilized. They calculated the rate of crust color change in meatballs by using fi rst-order kinetics: ...
... The mode of mass transfer in fried products is still a subject of debate, since several authors have described it differently. A general assumption that mass transfer in fried products is diffusion governed is often made, which implies that the concentration gradient is largely the main driving force for mass exchange between the product and the surrounding fluid (Ateba and Mittal, 1994;Chen and Moreira, 1997). Ngadi et al. (2006) ...
... The maximum force required to penetrate a sample at a certain displacement rate is interpreted as the textural quality of hardness, crispness, or crunchiness. Ateba and Mittal (1994) presented texture analysis results of fried meatballs, showing the effect of frying time. The break force peak was shown to increase with the frying time. ...
... It is supposed that in the process of water evaporation, volume expansion of water leads to the porous structure characterized by voids in the interior and crevices, crack and fine pores in the crust of batter, as reported for chickpea batter fried into boondi (Bhat and Bhattacharya 2001). Some kinetic studies of food quality changes such as surface color and texture during deep-fat frying have been carried out (Ateba and Mittal 1994;Baik and Mittal 2003;Nourian and Ramaswamy 2003a;Kumar et al. 2006). Two typical phenomena, i.e., protein denaturation and starch gelatinization happen during the frying of product. ...
... The activation energy was found to be 92.86 kJ/mol for the crust lightness change during the deep-fat frying of Bezhy. It is much higher than that of Gulabjamun (Ea = 43.52 kJ/mol, Kumar et al. 2006), tofu (Ea = 76.0 kJ/mol, Baik and Mittal 2003), meat balls (Ea = 16.92 kJ/mol, Ateba and Mittal 1994) and wheat flour-based donuts (Ea = 18.2 kJ/mol, Velez-Ruiz and Sosa-Morales 2003). The differences may be attributed to the different compositions and reactions involved, implying darkening of the Bezhy crust. ...
Deep-fat frying is one of the most prevail methods of food processing, which affect color and physical properties. The effects of frying temperature (150–180C) and time on the physical characteristics of cookie, including crust thickness, internal porosity, color and hardness, have been investigated. Kinetics of color and physical attributes of cookie were investigated using zero/first order of kinetics. Crust color was also evaluated and L*, a*, b* and ΔE, values were obtained. Further, rheological property of crust surface, i.e., hardness was examined. Hardness and L*, followed a first-order change, while the other parameters had zero-order kinetics. The temperature dependence of reaction's constants explained by the Arrhenius equation and activation energy was found to be in the range of 21.2–92.86 kJ/mol. The L*, crust thickness and ΔE had higher correlations with texture than internal porosity, which suggests that L* can reliably be used to predict the hardness of deep-fat fried cookie.Practical ApplicationThe physical properties of cookie such as color and texture have so important for consumers of food products. Since, texture measurement during processing is a time-consuming and destructive technique, finding another method for its evaluating will be beneficial. Therefore, the correlation between color and texture of cookie during deep-fat frying by applying image processing techniques was investigated. It was found a good correlation for L* and ΔE with texture than internal porosity. The activation energy of internal porosity was lowest of all the physical properties. It seems the L* can be reliably used to predict the hardness of deep-fat fried cookie. Therefore, by having enough knowledge on surface color of cookie, it will be possible to estimate texture properties.
... The temperature dependence of rate constants was evaluated using Arrhenius equation. Several authors used Arrhenius equation to describe the temperature dependency of rate constant of moisture loss and oil uptake in deep fat frying process (Ateba and Mittal 1994;Indra et al. 1999;Debnath et al. 2003;Math et al. 2004;Budzaki and Seruga 2005;Yildiz et al. 2007;Moreira et al. 2009;Bravo et al. 2009), as ...
... The activation energy for moisture removal was 14.34 KJ/mol in case deep fat frying of composite product samosaan Indian traditional filled pastry snack food, whereas, in case of vacuum frying of potato chips it was almost equal to that of Gethi (Indra et al. 1999;Moreira et al. 2009). The activation energy for moisture diffusion was 2.70 KJ/mol for beef meat ball frying and 97.69 KJ/mol in case of deep fat frying of catla catla fish (Ateba and Mittal 1994;Pandey et al. 2008). The activation energy for moisture diffusivity was 30 KJ/ mol whereas for fat diffusivity it was 5.5 KJ/mol in case of deep fat frying of korostula dough (Budzaki and Seruga 2005). ...
Investigation was carried out to study kinetics of moisture loss, oil uptake and tristimulus colour during deep fat frying of Gethi (Dioscorea kamoonensis kunth) strips. Deep fat frying of Gethi strips of size 6 × 6 × 40 mm was carried out in a laboratory scale fryer at different temperatures ranging from 120 to 180 °C. The investigation showed that the moisture loss and oil uptake followed the first order kinetics equation (r > 0.95, p < 0.05). The kinetic coefficients for moisture loss and oil uptake increased significantly (p < 0.05) with temperature from 0.166 to 0.889 min-1 and 0.139 to 0.430 min-1 respectively. The temperature dependency of rate constants for moisture loss and oil uptake values was described using Arrhenius equation (r > 0.99, p < 0.01). The activation energies for moisture loss and oil uptake were found to be 41.53 KJ/mol and 27.12 KJ/mol respectively. The hunter colour parameters were significantly affected by frying temperature and frying time. The hunter lightness (L) value increased with respect to frying time initially, followed by decline and same trend was observed at higher temperatures of frying with elevated rate, whereas hunter redness (a) value increased significantly (p < 0.01) with time as well as temperature of frying and obeyed zero order rate equation. The temperature dependency kinetic coefficients of Hunter (a) value were described by Arrhenius equation and the energy of activation for change in hunter redness was found to be 42.41 KJ/mol (r > 0.99, p < 0.01). The other hunter colour parameters such as chroma, hue angle and total colour difference were markedly affected by frying temperature as well as frying time.
... Márquez and Añ ó n (1986) used a first-order reaction approach to study the color development in fried potatoes. Ateba and Mittal (1994) Krokida, Oreopolou, Maroulis, and Marinos-Kouris (2001) assumed that the color parameters L * , a * and b * followed a first-order kinetics to determine the rate of color changes during frying of potato strips. Pedreschi et al. (2005) assumed that the color parameter a * followed a first-order kinetics to determine the rate of color changes during frying of potato and find a good correlation between the acrylamide content of the chips and their color. ...
... In order to obtain the specific reaction rate of color change k, the approach used by Ateba and Mittal (1994) was employed. They calculated the rate of crust color change by using a first-order kinetics: ...
The objective of this work was to study the kinetics of color development in blanched and blanched-NaCl impregnated potato slices during frying by using the dynamic method and also to evaluate the effect of NaCl in reducing acrylamide formation in potato chips. The measurement of color was done by using an inexpensive computer vision technique which allowed quantifying in a more precise and representative way the color in L∗a∗b∗ units of complex surfaces such as those of potato slices during frying. The effect of potato slice soaking in NaCl was evaluated not only for color change but also for acrylamide formation. Prior to frying, potato slices (Desiree variety, diameter: 37mm, width: 2.2mm) were blanched in hot water at 85°C for 3.5min; these slices were considered as the control. Slices of the same dimensions were blanched as in the previous step, and soaked at 25°C in a NaCl solution of 0.02g/l 5min at 200rpm of agitation. These samples were considered as NaCl soaked potato chips.Blanched and soaked slices were fried at 120, 140, 160 and 180°C until reaching moisture contents of ∼1.8% (total basis) for color evaluation. Acrylamide content was evaluated only in final samples fried from 120°C to 160°C. Color values in L∗a∗b∗ units were recorded at different sampling times during frying at the four mentioned temperatures using the total color change parameter (ΔE). Experimental data of surface temperature, moisture content and color change in potato chips during frying were fitted to empirical relationships, with correlation coefficients greater than 90%. A first-order rate equation was used to model the kinetics of color change. In all cases, the Arrhenius activation energy decreases alongside with decreasing chip moisture content. Soaking in NaCl solution of potato slices before frying reduced dramatically acrylamide formation in potato chips in ∼90% (average value) in comparison with control chips.
... Velez-Ruiz and Sosa-Morales (2003) analyzed changes in instrumental texture profile of wheat flour-based donuts during deep-fat frying at 180-200°C. Ateba and Mittal (1994) gave mathematical models describing the kinetics of crust formation and firmness changes during deep-fat frying of meatballs. Nourian and Ramaswamy (2003) explained the kinetics of textural changes during cooking and frying of potatoes and reported increase in textural properties with frying time, which followed a first-order kinetic model. ...
... Prediction of changes in texture during frying could be helpful in a better process control and improvement in overall acceptability of a fried snack food from ready-tocook frozen raw snack such as vegetable stuffed patties. Reports exist regarding the importance of controlled crispy texture during frying of potato chips (Smith 1975;Scanlon et al. 1994;Rosen and Hellenas 2002), donuts (Velez-Ruiz and Sosa-Morales 2003), salmon (Kong et al. 2007), and meat balls (Ateba and Mittal 1994). However, to the best of our knowledge, there are no reports available on the changes in texture during frying of snacks subjected to frozen storage or after thawing. ...
Kinetics of texture development during frying of snacks subjected to different initial conditions such as frozen, frozen–thawed,
and unfrozen was investigated. The temperature dependency of the changes in the form of reaction constants was explained by
Arrhenius equation. The increase in hardness and decrease in cohesiveness followed first-order reaction kinetics (R
2 = 0.94–0.99) in all the samples. Frozen samples showed induction (phase I) and development/degradation (phase II) periods
for textural parameters during frying. The activation energies for hardness were 33.81, 25.63, 19.09, and 20.13kJ/mole for
frozen (phase I and II), frozen–thawed, and unfrozen samples, respectively with the R
2 = 0.96–0.99. Frozen samples showed high activation energies for textural parameters during frying as compared to the frozen–thawed
and unfrozen samples. The increase in chewiness was found to follow the kinetics of zero-order reaction for all the samples.
Temperature and time were found to have a significant effect (P < 0.01) on the changes in textural profile during frying.
KeywordsKinetics–Frozen–Snacks–Frying–Texture
... Márquez and Añó n (1986) used a first-order reaction approach to study the color development in fried potatoes. Ateba and Mittal (1994) calculated first-order kinetic parameters for browning during the frying of meat balls. Krokida, Oreopolou, Maroulis, and Marinos-Kouris (2001) assumed that the color parameters L * , a * and b * followed a first-order kinetics to determine the rate of color changes during frying of potato strips. ...
... In order to obtain the specific reaction rate of color change k, the approach used by Ateba and Mittal (1994) was employed. They calculated the rate of crust color change in meatballs by using a first-order kinetics: ...
The objective of this work was to study the kinetics of browning during deep-fat frying of blanched and unblanched potato chips by using the dynamic method and to find a relationship between browning development and acrylamide formation. Prior to frying, potato slices were blanched in hot water at 85 °C for 3.5 min. Unblanched slices were used as the control. Control and blanched potato slices (Panda variety, diameter: 37 mm, width: 2.2 mm) were fried at 120, 150 and 180 °C until reaching moisture contents of ∼1.8% (total basis) and their acrylamide content and final color were measured. Color changes were recorded at different sampling times during frying at the three mentioned temperatures using the chromatic redness parameter a∗. Experimental data of surface temperature, moisture content and color change in potato chips during frying were fit to empirical relationships, with correlation coefficients greater than 90%. A first-order rate equation was used to model the kinetics of color change. In all cases, the Arrhenius activation energy decreases alongside with decreasing chip moisture content. Blanching reduced acrylamide formation in potato chips in ∼64% (average value) in comparison with control chips at the three oil temperatures tested. For the two pre-treatments studied, average acrylamide content increased ∼58 times as the frying temperature increased from 120 to 180 °C. There was a linear correlation between acrylamide content of potato chips and their color represented by the redness component a∗ in the range of the temperatures studied.
... The a*-value of fried chicken patties with PDF increased significantly compared with the control except for the 4.0% treated group samples (p < 0.05). The a*-value of cooked patties is related to the undenatured myoglobin and the formation of globin hemochromogen [32], and also related to Maillard reaction, which predominates all other reactions in the color formation at the surface of fried patties [33]. It is speculated that this parameter may be associated with the difference in the resource and the incorporation methods of the addition of non-meat ingredients, besides the method of processing. ...
A total of 150 chicken patties containing different concentrations of potato dietary fiber (PDF) (0.0–4.0%) (30 for every treatment) with three replicates were used to access the influence of PDF on their quality, microstructure, and thermal stability. PDF improved the quality of chicken patty, including significantly inhibiting dimensional change and improving water- and fat-binding properties and textural properties (p < 0.05). Moreover, PDF promoted a more homogeneous and dense meat–protein network structure to be formed. The results of thermal stability showed that PDF did not affect the thermal denaturation of proteins (p > 0.05). The samples with PDF (<3.0%) did not have a significant negative effect on sensory properties of chicken patty; meanwhile, there were more abundant nutrients and a lower energy value in samples with PDF compared with the control. Therefore, PDF could be a promising ingredient to improve the properties of chicken patties, which was related to the amount of PDF added and performed best at 3.0% level.
... Se han reportado los parámetros cinéticos de cambio de color para albóndigas de carne [4], papas fritas [2], [5], tofu [3] y Gulabjamun [6]; en ellos se señala la influencia de: la temperatura y composición del aceite, el tiempo de fritura y el tamaño de la muestra. ...
El objetivo de este trabajo fue modelar la cinética del cambio de color, de snacks de mandioca, durante su fritura por inmersión a 150, 170 ó 190°C. Los snacks preparados a partir de puré de mandioca extruidos fueron fritos en aceite de girasol y su cambio de color medido con colorímetro Hunter Lab D25-9. La luminosidad (L) disminuyó exponencialmente mientras que el parámetro redness (“a”) y el cambio de color total (DE) aumentaron con el incremento del tiempo de fritura; se utilizó una ecuación de primer orden para modelarlos. El parámetro yellowness (“b”) después de un incremento inicial, disminuyó linealmente con el tiempo de fritura. Los datos de contenido del contenido de agua de los snacks fueron ajustados a una relación empírica. La dependencia de la constante de velocidad del cambio de color total con la temperatura fue modelada mediante la ecuación de Arrhenius y su energía de activación disminuyó con la disminución del contenido de agua en el snacks.
... Zero order kinetic model was followed by a* value showing decreasing trend in the rate constant with increase in frying temperature. The accounted value of E a in the range of values (Table 2) as specified by Villota and Hawkes (1992) was found to close to the value 62.3 kJ/mol for hazelnut roasting (Ozdemir and Devres 2000) and higher than 16.9 kJ/mol for meatball frying (Ateba and Mittal 1994). ...
The present study was carried out to study the physico-chemical changes that take place in both product and oil during the deep fat frying of a traditional savoury snack ‘kodubale’, at 120–160 °C for 120–600 s using coconut oil (CO) and nutra-coconut oil (NCO). Further, kinetic studies on moisture loss, oil uptake, color and degradation of β-carotene, total polyphenol content and antioxidant activity for kodubale was carried out during frying as a function of temperature and time. The study showed that the kinetic coefficients for above parameters increased with temperature and time and the data obtained were well fitted with first order kinetic model. The results also revealed that NCO fried product retained major phenolic acids due to the presence of antioxidants in the NCO which was enriched with flaxseed oil concentrate. The fatty acids profile of oil extracted from products obtained by frying using NCO was characterized with higher ω-3 and ω-6 fatty acids content as compared to same obtained using CO. However, the breaking strength and sensory characteristics of CO and NCO fried kodubale was found to have no significant difference (p < 0.05).
... As shown in Table 5, the activation energy of the lightness (L*) was about 100.42 kJ/mol for the investigated samples. This value was higher than the activation energy during the frying of the tofu samples (76.0 kJ/mol) [Baik & Mittal, 2003], and meat balls (16.92 KJ/mol) [Ateba & Mittal, 1994]. The higher activation energy here implies that the L* is not much sensitive to the temperatures changes. ...
The aim of this study was to develop a kinetic model to describe the texture and colour changes of chicken sausage during superheated steam cooking. Chicken sausages were cooked at temperature ranging from 150-200°C with treatment times ranging from 2-6 mins. The texture profile was evaluated in terms of hardness, cohesiveness, gumminess, and chewiness, while the colour parameters were estimated in terms of lightness (L*), redness (a*), yellowness (b*), and total colour difference (∆E). Experimental data showed a gradual reduction in texture parameters as cooking times and temperatures increased. The L* value of the colour showed a linear reduction with cooking condition, while the a*, b*, and ∆E values showed a contrary effects. The decrease in texture parameters and L*-value of colour parameter followed the first-order kinetic model. While, zero-order kinetic model was adapted to fit the a* and b*. The modified first order kinetic showed a good fit for total ∆E. Significant correlations between colour and texture parameters were observed, which showed that a* alone could be used to predict the texture of chicken sausage.
... There are reports about the application of response surface methodology (RSM) for understanding the effect of different parameters on the rheological properties and optimization of processing parameters (Jayraj Rao and Patil, 2001;Diaz et al., 1996). First -order reaction kinetics mathematical models describing heat, moisture and fat contents were developed during deep fat frying of beef meatballs and validated against experimental data (Ateba and Mittal, 1994). Deep fat frying of breaded chicken pieces has been discussed from an engineering perspective using mathematical model to represent heat and mass transfer during frying (Mohan Rao and Delaney, 1995). ...
Deep fat frying of chevon meat was carried out in refined
sunflower oil and the effect of frying temperature and time on moisture and
fat contents was investigated. Experiment were designed based on central
composite, face centered designed with two independent variables namely,
frying oil temperature (170°-190°C) and frying time (2-10 min) with two
responses, moisture loss (%) and fat uptake (%). Quadratic model was fitted
to the data and optimization was done using response surface methodology.
The optimum conditions obtained were 182 °C oil temperature and 10 min
frying time resulting in moisture loss 34.85 % and fat uptake 35.21 %.
... [7] (figure 2). Results showed thickness of crust were significant for ratios that values were 3 and 1,2 mm for ratio 20 and10 respectively [8] (figure 3). At last, oil uptake % were 33 and 24 for ratio 20 and 10 respectively thus ratio 10 was suitable for frying of potato (p<0.05) ...
... rature during frying causes the surface temperature of the product to rise, leading to moisture evaporation which recedes inward as frying progresses. Thus, it is a moving boundary process with an interface that separates the core and the crust proceeding from the surface to the inner part of the food during frying (Ngadi, Watts, and Correia 1997). Ateba and Mittal (1994) used a very simple linear model to predict the development of crust thickness in meatballs. Crust was assumed to form at locations with temperatures ≥ 100°C. The authors reported good agreement between experimentally measured and predicted crust growth rate. The formation of crust is a signifi cant quality index for fried foods. Crust p ...
... There are reports about the application of response surface methodology (RSM) for understanding the effect of different parameters on the rheological properties and optimization of processing parameters (Jayraj Rao and Patil, 2001;Diaz et al., 1996). First -order reaction kinetics mathematical models describing heat, moisture and fat contents were developed during deep fat frying of beef meatballs and validated against experimental data (Ateba and Mittal, 1994). Deep fat frying of breaded chicken pieces has been discussed from an engineering perspective using mathematical model to represent heat and mass transfer during frying (Mohan Rao and Delaney, 1995). ...
... It is reasonable to assume that moisture content is negligible when equilibrium is reached in the frying process, so M e = 0 in Eq. (2) (Ateba and Mittal, 1994; Chen and Moreira, 1997; Williams and Mittal, 1999; Adedeji et al., 2009; Troncoso and Pedreschi, 2009). Eq. (2) is made simpler as follows when M e is very small, additionally it must be mentioned that only first term in equation was considered to calculate the values of the diffusion coefficients: ...
The objective of this study was to evaluate the effect of different batter formulation on mass transfer during deep fat frying of shrimp nuggets prepared without a pre-frying step. The effects of soy and corn flour (5, 10%) addition to the batter formulation, frying temperature and time on mass transfer were determined. The results showed an interaction effect of these processing conditions on mass transfer. The most reduction in fat absorption was observed when samples were coated with batter contained 10% soy flour and fried at 190 ˚C. The first order kinetic based on the Fick’s law were used to describe moisture transfer data. The effective moisture diffusivity ranged between 2.05×10-8 to 5.71×10-8 m2/s with R2 between 0.91 to 0.98, and fat transfer rate constant was between 3.5×10-3 to 7.8×10-3 s-1 with R2 from 0.82 to 0.99. Activation energy obtained from the Arrhenius plot for the effective moisture diffusivity ranged between -18.42 and -23.84 kJ/mol.
... The chicken nuggets were separately placed in frying baskets and fried. After frying, samples were allowed to drain for a short time before being blotted gently with dry tissue paper to remove excess oil on the surface (Ateba & Mittal, 1994;Debnath, Bhat, & Rastogi, 2003). The coating and core portions of the chicken nuggets were carefully separated by hands before further analysis. ...
The effect of a microwave pretreatment at different time duration on the mass transfer of chicken nuggets during deep-fat frying was studied. Coated chicken nugget samples pretreated in a microwave oven for 1–2 min were fried at 160 °C for times ranging from 0 to 300 s to evaluate the mass transfer as compared to the samples without a microwave pretreatment. Microwave pretreatment had a significant effect on moisture loss and oil uptake of chicken nuggets during deep-fat frying.
... An appropriate experimental design is fundamental for enabling the researchers to explore the process under study and leading him successfully to its optimization obtaining the maximum or the minimum, if they exist, or to determine a region in the total space of the factors in which certain desirable operating conditions are satisfied. [22] Most research reports available in the literature relates to products like Tofu [23] ; French fries [24] ; potato strips [11] ; potato [16,25,26,27,28] ; Donut [29] ; Meat ball [30] and cassava chips. [31] No information is available on the deep fat frying of yams slices with respect to optimizing the conventional blanching conditions as it affects quality parameters. ...
The effect of low-temperature blanching and frying time at a frying temperature of 170°C on moisture and oil contents, breaking force and colour of yam chips was investigated using response surface methodology to establish the optimum blanching conditions and frying time. A central composite rotatable design was used to study the effects of variation in levels of blanching temperature (60–80°C), blanching time (1–5 min) and frying time (2–6 min) on quality attributes of yam chips. The effect of blanching temperature and frying time was more significant than the time of blanching on the quality attributes. The response variables were fitted to predictive models applying multiple linear regressions. Statistical analysis with response surface regression showed that moisture content, oil content, breaking force and L* (lightness) parameter were significantly (P < 0.05) correlated with blanching temperature and time and frying time. However, the regression equation showed a poor fit for a* and b* respectively. The optimum conditions were a blanching temperature of 70–75°C, blanching time of 4–5 min while frying for about 5 min.
... Mathematical models based on heat transfer have successfully been applied to food products for thermal process calculation and optimization by Teixeira et al. (1969a,b) and Teixeira and Manson (1982). More recently, a model to predict heat, moisture and fat transfer for the deep-fat frying of beef meatballs at 159 ± 1°C was proposed by Ateba and Mittal (1994). Thorvaldsson and Janestad (1999), developed and validated a model describing the simultaneous heat, water and vapour diffusion to predict the diffusion of water inside food products during heat processing. ...
This paper presents an analytical model for the prediction of cooking time of meat products in industrial steam ovens. To achieve this aim, the paper first develops a mathematical model for cooking meat, which is numerically solved and validated on the basis of the outcomes of an appropriate experimental campaign. Numerical simulations are then performed setting different values of sample sizes, with the aim to derive a parameterised model able to analytically reproduce the time–temperature curves of meat samples. As input the model developed requires an appropriate “translation” parameter, describing the shape of the time–temperature curve as a function of the sample size and diameter; as output it gives an estimate of the cooking time. The “translation” parameter is provided as a result of the numerical simulations for a wide range of sample size and length. The analytical model is validated by comparing the predicted cooking time with experimental cooking data related to time–temperature curves of seven meat samples. The comparison shows that the average percentage deviation between experimental results and model predictions is about 4.6%, proving good performance of the model developed. The model can be successfully used to estimate the meat cooking time starting from typical values of meat parameters, and, due to its simplicity, it appears to be suitable for direct implementation as a tool to monitor and automate the industrial meat cooking treatments by means of computer control.
... A constant value during the frying process was assumed. It is reasonably to assume that moisture content is negligible when equilibrium is reached in the frying process, so m e ¼ 0 in Eq. (1) (Ateba & Mittal, 1994;Chen & Moreira, 1997;Williams & Mittal, 1999). The second model considers that effective moisture diffusion coefficient is no longer a constant value but rather a function of time due to the changes in physical properties of the product during frying. ...
The objective of this research was to determine the kinetics of water loss and oil uptake during frying of pre-treated potato slices under vacuum and atmospheric pressure. Potato slices (diameter: 30 mm; width: 3 mm) were pre-treated in the following ways: (i) raw potato slices “control”; (ii) control slices were blanched in hot water at 85 °C for 3.5 min; (iii) blanched slices were dried in hot air until reaching a moisture content of ∼0.6 g water/g dry basis. The slices were fried under vacuum (5.37 kPa, absolute pressure, at 120, 130 and 140 °C) and atmospheric conditions (at 180 °C). Two models based on the Fick's law were used to describe water loss: (i) with a constant effective diffusive coefficient; and (ii) with a variable effective diffusive coefficient. Oil uptake data were fitted to an empirical model, with a linear behavior for short times whereas the model was time independent for long times. The variable diffusivity model better fitted experimental water loss, giving values of effective diffusivity between 4.73 × 10−9 and 1.80 × 10−8 m2/s. The proposed model for the study of the kinetics of oil uptake fitted the experimental data properly. Control and blanched vacuum fried potato chips increased their final oil contents to 57.1% and 75.4% respectively, when compared with those fried at atmospheric pressure. However, the oil absorption of dried vacuum fried potato chips diminished by ∼30%.
... The authors observed high correlation between colour parameters and oil degradation during frying. Ateba and Mittal (1994) modelled kinetics of development of crust colour in meatballs during frying using the first-order reaction kinetics. Krokida, Oreopoulou, Maroulis, and Marinos-Kouris (2001a, b) also applied the first-order kinetics model to describe colour changes in French fries during frying process. ...
Quality changes in chicken nuggets fried in different mixtures of hydrogenated and non-hydrogenated canola oils were studied. Colour, texture, oil and moisture contents of the chicken nugget samples fried at 190 °C for 30, 60, 90, 120, 180, 240 and 300 s were investigated. The proportions of hydrogenated to non-hydrogenated frying oils used in the study were 0%, 20%, 40%, 60%, 80% and 100%.Results indicate that increase in frying time resulted in decreased product lightness (L*) whereas redness (a*) and yellowness (b*) increased. The maximum load to puncture increased with increasing frying time. In addition, oil content increased slowly with frying time, and moisture content decreased as expected. Both frying times and oil types have significant effects on the quality parameters investigated. First-order kinetic equation was used to describe colour changes as well as oil and moisture contents of the samples. Oil and moisture contents had negative correlation relationship. With increasing degree of oil hydrogenation, the surface colour of the fried chicken nuggets samples were lighter, texture increased, oil and moisture contents decreased.
... At the surface of the product, moisture is in instantaneous equilibrium with oil (Ateba and Mittal, 1994). The boundary condition takes the form: ...
This paper studies the energy valorization of sewage sludge using a batch fry-drying process. Drying processes was carried out by emerging the cylindrical samples of the sewage sludge in the preheated recycled cooking oil. Experimental frying curves for different conditions were determined. Calorific values for the fried sewage sludge were hence determined to be around 24 MJ kg(-1), showing the auto-combustion potential of the fried sludge. A one-dimensional model allowing for the prediction of the water removal during frying was developed. Another water replacement model for oil intake in the fried sewage sludge was also developed. Typical frying curves were obtained and validated against the experimental data.
Summary
The current study was conducted to investigate the relationship between the sensory evaluation of various food under the test (fish, potatoes and chicken and falafel) fried in sunflower oil at the temperature of 180 ± 5 ° C, and the physical and chemical changes that occur to oil used for frying these foods, and studying the effect of oil used for deep frying after it has been rejected by sensory Judges on the health.
This study included the results of three experiments:
The first one was on the sensory evaluation results showed significantly decreased (P <0.05) in the rates sensory scors (taste , odor, color and texture) of the food fried and the oil heated without food of five grades using preference scale of which was performed by ten Judges and up to the point of sensory rejection 1.48 ,1.65 ,1.75, 1.8 ,1.93 during the frying for 30, 20, 45, 35 and 75 hours for each of the food potato, fish, chicken, falafel, oil heated without food, respectively.
While the second was the physical and chemical tests on the oil had been used for frying up to the point of sensory rejection and the following results as follows :
1. It was noted that the viscosity was significantly increased ( P<0.05) from 48.5 (cP) for fresh oil (Control) and up to the point of sensory rejection (75 ,76 ,84, 84 ,253 cP) of the oil used for frying chicken, fish, falafel, potatoes and oil heated without food, respectively.
The result also indicated that a significant differences (P<0.05) among treatments at the point of sensory rejection were observed exept falafel and potato. Also the results indicated positive(P<0.05) correlation Coefficient (r) between viscosity and the refractive index, foam height, color, acid value, polar compounds and para-anisidin value, however the correlation of viscosity (P<0.01) with smoke point and Iodine value were negative for all treatments.
2. The study showed a significant increase (P<0.05) in the refractive index value at 25C° from (1.4880) for the fresh oil and up to 1.4894 ,1.4897 and 1.4897 ,1.4914 ,1.4926 for points of sensory rejection for oil used for frying chicken, falafel, potatoes, fish and oil heated without food, respectively. Falafel and potato refractive index were not significantly different(P<0.05) at the point of oil rejection while a significant differences were found between other food treatments.
A positive correlation Coefficients (P<0.01) between RI and the previous properties was found, exept smoking point and Iodine (P<0.05) Value.
3. smoke point of fresh oil was found to be 230 Cە and significantly decreased (P<0.05) at the point of sensory rejection of the used oils to 195 , 195 , 190 , 190 and 180 C° for frying chicken, falafel, potatoes, fish and oil heated without food on the respectively. The differences among the treatments at the point of rejection were not found significant (P<0.01) always.
A Negative correlation Coefficients (P<0.01) between smoke point and the previous properties was found, except Iodine Value.
4. The foam height of the used oils for frying fish and falafel, potatoes, chicken and oil heated without food showed a significant (0.05>P) increase from that of fresh oil of 0.0 ml and up to 100, 100, 100, 180 and 220 ml at the point of sensory rejection respectively. The above mentioned results shows no significant differences were found between frying fish, falafel and potato from one side and chicken and heating oil with out food from the other side.
A positive correlation Coefficients (P<0.01) between foam height and the previous properties was found except smoke point and Iodine Value.
5. significant increase (P<0.05) in the amount of Photometric Color Index (PCI) of (0.2) of the oil fresh and up to the point of sensory rejection (47.6. , 31.2 , 21.8 , 12.9 and 12.6) used for frying chicken and frying fish and cooking oil heated without food and used for frying falafel and potatoes, respectively. And indicated that a significant difference (P<0.05) between treatments at the point of sensory rejection except falafel and sweet potato. and significant increase (P<0.05) in the amount of color were determent by Lovibond, at (0.5) of the oil fresh and up to the point of sensory rejection 3.5 , 3.5, 2.5, 2 and 2 were used for frying chicken and frying fish and cooking oil heated without food and used for frying falafel and the fried potatoes, respectively. And indicated that a significant difference (P<0.05) between treatments except among chickens and fish, as well as between falafel and potato. A positive correlation Coefficients (P<0.01) between color change and the previous properties was found except smoke point and Iodine Value. .
6. significant increase were observed in the (P<0.05) the number Peroxide Value 1.8 meq/kg of fresh oil to the maximum increases with the passage of time deep frying up to the 34 , 30 , 20 , 21 and 18 meq/kg and then drop down to the point of sensory rejection (21 , 14 , 12 , 8 and 3) meq/kg used for frying fish, potatoes, falafel, chicken and oil heated without food, respectively. that a significant difference was observed and that is (P<0.05) between treatments except between the potatoes and the falafel. The correlation coefficient between it and all the tests were not found significant (P<0.01) always. exept fish treatment were correlation coefficient between peroxide Value and all the tests recorded in the number (1), and reverse correlation (P<0.01) with a smoke point and Iodine value, and correlation coefficient between it and the polar compounds , Para Para- Anisidin and acid value for falafel and chicken treatments, as well as a positive correlation (P<0.01) bonds with the conjugate diene , and Negative (P<0.01) for the Iodine value of the chicken Treatment.
7. significantly decreased (P<0.05) in Iodine value at (124) g / 100 g of the oil fresh and up to the point of sensory rejection 102 , 92 , 90 , 89 and 72 g / 100 g used for frying fish and falafel, potatoes, chicken and oil heated without food, respectively, and this indicated that a significant difference (P<0.05) between the fish and oil heated without food , and with there and other treatments (potatoes, falafel and chicken ), A Negative correlation Coefficients (P<0.01) between Iodine value and the previous properties was found, except smoke point .
8. The study showed a significant increase (P<0.05) in the Acid Value from 0.26 mg KOH / g for fresh oil up to the point of sensory rejection 1.34 , 1.34 , 1.29 , 1.23 , 1.11) mg KOH / g for oil used for frying fish , falafel, chicken , oil heated without food , and potatoes, respectively. And indicated that a significant difference (P<0.05) between the fish and falafel and chicken and between the treatment of potatoes. A positive correlation Coefficients (P<0.01) between Acid Value and the previous properties was found except smoke point and Iodine Value.
9. There was Significant increase (P<0.05) in the Para – Anisidin Value 2 mol / kg of fresh oil and up to the point of sensory rejection 64.9 54.9 41.8 39.3 and 35.9 mol / kg of oil heated without food , fish , falafel , chicken and potato respectively. and indicated that a significant difference (P<0.05) between the fish and the oil heated without food, as well as between them and the other treatments as well as a significant difference (P<0.05) of potatoes and falafel. and Para - Anisidin . A positive correlation Coefficients (P<0.01) between Para - Anisidin Value and the previous properties was found except smoke point and Iodine Value.
10. Polar compound of fresh oil was found to be 13.1 %ە and significantly increased (P<0.05) at the point of sensory rejection of the used oils to 49.1 , 38.3 , 33.2 , 32.4 and 31.5 mol / kg of oil heated without food , oil used for frying falafel , potato, fish and chicken, respectively. And indicated that a significant difference (P<0.05) between the treatments. A positive correlation Coefficients (P<0.01) between Polar compound and the previous properties was found except smoke point and Iodine Value.
11. It was noted that the Conjugated Dienoic Fatty Acids was significantly increased ( P<0.05) in absorbance at wavelength 232 from 0.178 nm of the oil fresh and up to the point of sensory rejection 0.926 , 0.799 , 0.798 and 0.605 of the oil used for frying fish and potatoes, chicken, falafel and oil heated without food, respectively. And indicated that a significant difference (P<0.05) between the fish and the other treatments as well as between each of potatoes, chicken and falafel and oil heated without food. A positive correlation Coefficients (P<0.05) between Conjugated Dienoic Fatty Acids and the previous properties was found except smoke point and Iodine Value , except peroxide value .
12. Gas – liquid chromatography (GLC) technique was used to measure the proportions of saturated fatty acids in all treatments hence the results showed an increase in plasmatic, stearic and oleic acids ratios with a decrease in the ratio of linoleic at the point of sensory rejection compared to fresh oil. The data shows a significant differences(0.05>P) in linoliec content between fresh oil 57.17 % and the rest of the treatment at the rejection point 55.81 > 55.11 > 53.31 > 52.08 > 47.98 % of oils used for frying food falafel, fish, potatoes and chicken, as well as heated without food, respectively.
13. At the point of sensory rejection, the highest rate of oil uptake was for Falafel (19.2%) compared to other foods (17.2> 6.3> 1.3%) for each of potatoes, chicken and fish, respectively).
14. Infra red schemes of the oil used in deep frying showed an effective overlap between the active group’s peaks and occurrence of new peaks indicate the deterioration of the oil.
Third: the biological impact
A. Blood tests
1. level of the Triacylglycerol significant increase (P <0.05) in the serum of rats fed diet containing 15% of the fresh oil compared with the level in the serum of rats fed on diet containing oil oxidized for frying food used and the same percentage 15%.
2. The study showed a significant increase (P<0.05) in the level of total cholesterol (103.9) mg / 100 ml of blood serum of rats fed diet containing 15% of the oil used for frying chicken, compared with the level of total cholesterol (85.8) mg / 100 ml of rat serum fed on diet containing 15% fresh oil. And the level of total cholesterol significant positive (P<0.05) for the correlation coefficient between this and all the tests for the refractive index and viscosity and a smoke point . height foam , acid value , Para – Anisidin value , Conjugated Diene and polar compound , and Negative correlation (P<0.05) with a smoke point and Iodine value, the treatments of potato, chicken and falafel. And Significant Negative correlation coefficient (P<0.05) between this and all the tests refractive index and viscosity and a smoke point and foaming and acid value , Para – Anisidin value , Conjugated Diene and polar compound, as well as positive correlation coefficient (P<0.05) with a smoke point and treating a number of iodized oil, fish and heated without food. .
3. Increase significant (P<0.05) in level of Low-density lipoprotein (Cholesterol-LDL) (75.6 , 75.2, 64.7, 55.3 and 52.5) mg / 100 ml in the serum of rats fed on the blood of the user to frying oil and chicken oil heated without food and oil used for frying potatoes, fish and Falafel , respectively, compared with 41.59 mg / 100 ml in blood serum of rats fed diet containing the fresh oil. A positive correlation Coefficients (P<0.05) between Low-density lipoprotein and the previous properties was found in number (2), exept smoking point and Iodine Value.
.
4. Decrease significant (P<0.05) in the level of high-density lipoprotein (Cholesterol-HDL) (23.4 , 20.4 , 19.1 , 16.9 and 14.6) mg / 100 ml in serum rats fed on oil used for frying falafel, potatoes, fish, chicken and oil heated without food, respectively, compared with (29.4) mg / 100 ml in the blood serum of rats fed diet containing fresh oil. A Negative correlation Coefficients (P<0.05) between high-density lipoprotein and the previous properties was found in number (2), exept smoking point and Iodine Value.
5. The study showed a significant increase (P<0.05) in the leve Malondialdehyde from (2.66) μmol / L in the blood serum of rats fed diet containing fresh oil and up to (4.24 , 4.12 , 3.72 , 3.5 and 3.32) μmol / L in the serum of rats fed on the blood of the user to frying oil and fish oil , heated without Food , falafel , potatoes and chicken respectively,. A positive correlation Coefficients (P<0.05) between Malondialdehyde and the previous properties was found in number (2), exept smoking point and Iodine Value, and all the treatments studied. except the viscosity for the treatment of potatoes, refractive index for the treatment of falafel, the refractive index , viscosity and peroxide value for the treatment of chickens, and the peroxide value from oil heated without food.
6. Indicates decrease significant (P<0.05) in the level of Reducing Glutathione (GSH) 117.6 , 116.6 , 116.4 , 114.8 and 108.2 μmol/ml in serum rats fed on oil heated without food , oil used for frying falafel , potato , fish and chicken, respectively, compared with 119.5 mg / 100 ml serum in the blood serum of rats fed diet containing the fresh oil.
7. level of the enzyme (Aspartate aminotransferase) (AST) significant increase (P<0.05) of the 131.3 , 116.5 , 90.3 IU / L in plasma of rats fed oil user to frying fish, chicken , potatoes, respectively, and the decrease significant (P<0.05) of the enzyme 57.8 and 57.5 IU / L for oil heated without food , falafel, respectively, compared with (72.5) IU / L serum in serum rats fed on diet containing fresh oil.
8. level of the Enzyme Alanine aminotransferase (ALT) increase significante (P<0.05) of the 67 , 62.5 , 44.3 , 37 and 27 IU / L in plasma of rats fed oil heated without food and , chicken , falafel, fish and potatoes, respectively, compared with (23) IU / L serum in serum rats fed on diet containing the fresh oil.
9. level of the enzyme (ALP) Alkaline phosphatase increase significante (P<0.05) of the 226 , 202 , 178 , 71 and 70 IU / L in plasma of rats fed oil heated without food , chicken , falafel, fish and potatoes, respectively, compared with ( 43) IU / L serum in serum rats fed on diet containing the fresh oil. A positive correlation Coefficients (P<0.05) between (ALP) and the previous properties was found in number (2), exept smoking point and Iodine Value.
10. The study showed a significant decreased (P<0.05) for daily consumption , the increase weighted and content of protein and Glycogen liver rats fed on diet containing oil user to frying fish, as well as significantly decreased (P<0.05) content of the liver Glycogen fed on chicken treatment , compared to with daily consumption of rats fed on diet containing diet containing the fresh oil.
11. The influence un normal condition healthy of food that contains the oil oxidize to heat during deep-frying the liver tissue of rats fed on diet containing 15% oil compared to liver tissue of rats fed on diet containing 15% oil, fresh (compare-Control).
12. The study showed a significant increase (P<0.05) Total Cholesterol, Low-density lipoprotein, Malondialdehyde, Enzymes(ALT,AST and ALP),and Decrease of high-density lipoprotein, Reducing Glutathione, in the seram of rats were fed diet containing oxidized oil compared with fresh oil , that indicators of un normal condition healthy.
Chhena jhili is a deep fat fried product prepared from the mixture of Chhena, refined wheat flour and sugar. The effect of frying temperature (120–140 ) and frying time (3–20 min) on texture and color were investigated. The kinetics of texture and color followed the zero order kinetics for hardness, firmness, and L value whereas the stiffness and color change followed a first order kinetics. Activation energy for both texture and color falls in the range of 35.11–82.04 and 32.59–38.46 kJ/mol, respectively. Mathematical model was developed for heat and mass transfer during deep fat frying of Chhena jhili. The fat uptake during the deep fat frying is explained by the first order kinetic model. The convective heat transfer coefficients determined by transient heat transfer equation is 69.80–103.18 W/m2K in the temperatures range of 125–145C. The moisture transfer coefficient was increased with increase in temperature and was ranged from to 2.848 to 7.543 m/s. This study focuses on basic information on fryer and oil selection for frying. Effect of frying temperatures and frying time on product quality was analyzed. It provides overview of fryer design on the basis of the type of product to be fried. Frying time is longer at lower temperatures and frying at lower temperatures results in lighter color, and increased oil absorption. High-temperature frying leads to thinner crusts and less oil absorption.
A comprehensive understanding of the electromagnetics and thermal aspects of the thawing of frozen foods in a domestic microwave oven cavity was developed through a model that two-way couples Maxwell’s equations with the heat conduction equation with continuous variation of dielectric and thermal properties with temperature. Tylose, a material with properties similar to those of lean beef, was used to experimentally validate the model. Temperatures were measured using fiber optic and infrared sensors. Various salt contents that were used in formulating the tylose represented important variations in dielectric properties, latent heat release, and initial freezing point. Spatial and time variations of all important parameters are used to explain the results. As material thaws, total energy absorption decreases, a novel result that is explained by reference to continuous changes in dielectric properties. Shifts in the resonant frequency of the cavity as load size changes explain the changes in total energy absorption with size. Inverter heating, a newer technology that claims superiority over ordinary cycled heating, produced only minimal differences in temperature uniformity or color.
Deep fat frying of chicken was carried out at 160, 170 and 180°C in refined sunflower oil. The effect of frying temperature and duration on moisture and fat contents was investigated using response surface methodology. Experiments were designed based on central composite, face centered design having two independent factors and two responses. Using these models changes in moisture and fat contents of the product as a function of frying time and oil temperature were predicted and displayed in the form of response surfaces and optimization of process conditions were also established. Time of frying and temperature were optimized as 10 min and 177°C, respectively and the optimal moisture and fat contents of the product were 32.73% and 33.2%, respectively.
Frying kinetics of Catla catla fish at 160, 170 and 180°C for 0 to 8 min showed variations in moisture, fat and product temperature at the centre ranging from 75.5 to 31.2, 6.3 to 30.8% and 24.1 to 95.4°C, respectively. The experimental data fitted into first order kinetic model for moisture content (r2 > 0.989) and second order polynomials (r2 > 0.990) for fat content as well as product temperature. Activation energy using Arrhenius equation was 97.7 kJ mol-1 Moisture and fat content variations were inversely correlated (r2 >0.993). Moisture diffusivities at 160, 170 and 180°C were 0.7005x10-8, 1.32x10-8 and 2.3086x10-1 mV and thermal diffusivity obtained using the rate of change in thermal profile at the centre of fish were 1.076x10-8, 1.0243x10-8 and 1.005x10-8m 2s-1 respectively.
Fry-drying is an alternative for heat and mass transfer intensification. The process reuses waste oil as a heating medium for drying by contact with the wet sludge. At the end of the process, a stable derived fuel is obtained, a granular solid composed of the dried indigenous sewage solid and the impregnated oil. The fry-dried sludge is storable and transportable without any pathogen elements. Knowledge about heat and mass transfer rates during the frying process is essential in order to assess the quality of the final product such as calorific value, oil uptake, porosity changes, etc. The heat transfer properties including transfer by free convection between the solid and the frying oil are fundamental for the process design and manufacturing of the fry-dried product. The convective heat coefficient by temperature measurement and overall energy balance calculation is determined. The heat flux is calculated from the fry-drying kinetics including moisture loss and oil intake kinetics. Various hydrodynamic regimes for convective heat transfer during the frying process are discussed (non-boiling, boiling, and low-boiling regime). A dimensionless formulation for estimating the convective transfer is proposed.
Kinetics of color changes of a tofu (extra firm variety) was studied during deep-fat frying at 147–172°C. Lightness (L*) decreased exponentially from 85.5 to 68.0 with frying time, while redness (a*) and total color change (ΔE) increased from −1.17 to 6.72 and from 0 to 26.7, respectively. Yellowness (b*) increased from 18.8 to 34.5 then decreased exponentially to another minimum of 29.4. All the color parameters followed first-order reaction kinetics. Temperature dependency of the reaction rate constant was modeled using Arrhenius equation. The activation energy for color parameters was 76.0–165kJ/mol. Good agreement was observed between calculated and measured data (R2=0.968–0.996).
Gulabjamun, a popular Indian milk sweet, is prepared by deep-fat frying of balls of dough made of khoa, wheat flour and baking powder, and subsequent dipping in sugar syrup. Kinetics of colour and texture changes in gulabjamun balls were investigated with regard to frying temperature (120, 130, 140°C). Crust colour was evaluated in terms of CIELAB parameters L*, a*, b*, and ΔE, and rheological properties in terms of hardness, stiffness and firmness. Frying-induced surface browning was reflected in a decreasing lightness value L* as well as the ratio of yellow hue index b* and red hue index a* and total colour expressed in terms of ΔE, L* following a zero-order change whereas the other parameters, a first-order change. Increase in the texture parameters hardness and firmness followed zero-order reaction kinetics whereas stiffness rise followed a first-order reaction. The temperature dependence of reaction constants could be explained by the Arrhenius equation. Activation energy was also obtained for both the colour and texture changes, which were in the range of 24.5–77.6kJ/mol. High correlations between colour and texture parameters were observed and it was concluded that L* alone could be used to predict the firmness of deep-fat fried gulabjamun balls.
The effect of solute impregnation on water loss and oil uptake during potato strip frying was studied. Blanched potato strips were impregnated at 25°C by soaking in a solution of sucrose–NaCl–water, 20–5–75% by weight. After rinsing and air drying, strips were deep fried in sunflower oil at 160, 170 and 180°C. A control treatment, consisting of potato strips blanched but not soaked and later air dried was also conducted. Solute impregnation provided a decrease of the oil uptake. Two models, based on Fick's law were used to describe water loss during frying. The first one is the classic model with an effective moisture diffusion coefficient assumed a constant value. The second model considers that diffusion coefficient varies during the frying process. For a given frying temperature, constant diffusion coefficient for control potatoes resulted in lower values than the impregnated ones. The variable diffusivity model showed a two-stage behavior: during the first stage of frying, diffusion coefficient increased with frying temperatures, but from a given time on an inverse behavior began. This last fact was found to be related to an increase of the measured peak force needed to penetrate the potato crust.
An artificial neural network (ANN) was developed to predict heat and mass transfer during deep-fat frying of meatballs. Frying time, radius of meatball, fat diffusivity, moisture diffusivity, heat transfer coefficient, fat conductivity, initial moisture content, thermal diffusivity, initial meatball temperature and oil temperature were all input variables. Temperature at meatball geometrical centre (T0), average temperature of meatball (Tave), average fat content of meatball (mf,ave), and average moisture content of meatball (mave) were outputs. The data used to train and verify the ANN were obtained from validated mathematical models. Trained ANN predicted T0, Tave, mf,ave and mave with 0.54, 0.14, 0.03 and 0.10% mean relative errors, respectively.
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.
A restructured potato model system was fried in canola oil for 5, 10, or 15 min at 170, 180, or 190C and tested in a Dynamic Mechanical Analyzer. Selected mechanical properties were measured using puncture and three-point bending cells. Forces involved in puncture were a combination of tension, compression, and shear, while the three-point bend test studied the crust flexural properties. Crust deformability seemed to be governed by internal structural yielding. Maximum force at rupture increased significantly with both frying time and temperature. Failure criteria identified and standardized types of failure observed during bending tests.
The effect of added fructose (0–10% w/w) on restructured potato product surface characteristics, mechanical properties, moisture loss, oil uptake and color changes during deep-fat frying was investigated. The apparent fractal dimension derived from the silhouettes of the sample contour was related to surface ruggedness, and displayed a marked linear effect of the added fructose on reducing its value from 1.27 to 1.08. The apparent fractal dimension correlated linearly with oil uptake and UR, suggesting a practical criterion for predicting oil uptake during deep-fat frying. Added fructose reduced water diffusivity coefficients of pre-fried specimens from 2.00 × 10−9 to 1.26 × 10−9 m2/s. Porosity ranged from 0.79 to 0.82.
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.
Our objectives were to mathematically model heat transfer in meat patties during single-sided pan-frying without and with turn-over, using the finite element method. Moisture loss rate was determined and included in the model to account for evaporation loss. The model was validated by comparing predicted and experimental temperature profiles monitored at three axial positions during pan-frying (one side and turn-over) at 140 and 180°C. Moisture loss rate, cooking time, and crust formation were functions of pan temperature and/or turn-over frequency and time. The least cooked point, predicted at the periphery of the top surface (no turnover) and midplane (one turn-over), required 20 and 10 min, respectively, to be cooked well-done at 160°C. Turning-over more than once slightly decreased frying time, but may not produce crusted surface.
Acrylamide formation in French fries was investigated in relation to blanching and asparaginase soaking treatments before final frying. Par-fried potatoes of Bintje variety were prepared by cutting strips (0.8×0.8×5cm) which were blanched at 75°C for 10min. Unblanched strips were used as the control. Control or blanched strips were then dried at 85°C for 10min and immediately partially fried at 175°C for 1min. Finally, frozen par-fried potatoes were fried at 175°C for 3min to obtain French fries. Pre-drying of raw or blanched potato strips did not generate acrylamide formation as expected. Partial frying of pre-dried control potato strips generated 370μg/kg of acrylamide and the final frying determined French fries with 2075μg/kg of acrylamide. When control potato strips were treated with a 10000 ASNU/l asparaginase solution at 40°C for 20min, the acrylamide formation in French fries was reduced by 30%. When blanched potato strips were treated in the same way, the produced French fries have 60% less acrylamide content than blanched strips without the enzyme treatment. Soaking of blanched potato strips (75°C, 10min) in an 10000 ASNU/l asparaginase solution at 40°C for 20min is an effective way to reduce acrylamide formation after frying by reducing the amount of one of its important precursors such as asparagine.
Copyright © 2007 Elsevier Ltd. All rights reserved.
The objective of this work was to study the kinetics of crust browning during deep-fat frying of impregnated and control potato strips (Solanum tuberosum L., Desiree variety) by using a dynamic method and, with the obtained kinetics parameters, to predict the color change during frying. Blanched potato strips were impregnated at 25 °C by soaking in solutions of corn syrup DE 42-NaCl, 50–3% by weight, and NaCl 3% by weight. After rinsing and air drying, the strips were deep fried in sunflower oil at 160, 170 and 180 °C. A control treatment, consisting of potato strips blanched but not soaked was also conducted. Experimental data of surface temperature, mean moisture content of potato strips and crust color changes during frying were fit to empirical relationships, with correlation coefficients greater than 99.0%. A first-order rate equation was used to model the kinetics of color change. In all cases, the Arrhenius activation energy decreased alongside with decreasing mean moisture content, suggesting a possible color development rate control from a chemical step to a diffusional one. The kinetic parameters were employed to predict the color change during the deep-fat frying with RMS's values in the range of 5.1–10.5%.
The objective of this research was to study some physical properties of pre-treated potato slices such as moisture and oil content, texture and color during frying at 120, 140, 160 and 180 °C. Slices (Desiree variety, diameter: 30 mm, width: 2.0 mm) blanched in hot water at 85 °C for 3.5 min were considered as the control. NaCl soaked chips were previously blanched as indicated before and immersed in a 3% NaCl solution for 5 min at 200 rpm of agitation and 25 °C. The moisture loss profiles were similar for chips pre-treated in the two ways during frying. Oil uptake increased up to ∼20% as the frying temperature decreased; soaking of blanched chips in the NaCl solution decreased slightly the oil absorption in ∼7%. Color values in L∗a∗b∗ units were recorded at different sampling times during frying at the four mentioned temperatures using the total color difference (ΔE) and a Minolta colorimeter. Soaking of blanched slices in the NaCl solution producer paler chips after chips diminishing the final values of ΔE in 6%, 16%, 9% and 23 % with respect to those corresponding to control chips after frying. Textural changes in fried potato slices were followed by the parameter maximum force (MF). Soaking in NaCl of blanched chips increased its crispness after frying at 120, 140, 160 and 180 °C in 15%, 13%, 11% and 11%, respectively.
The goal of this research was to investigate the influence of the degree of hydrogenation of frying oil on quality and textural changes in chicken nuggets during deep-fat frying. Thermal stabilities of the frying oils were also studied. The frying oil consisted of blends of hydrogenated and non-hydrogenated oils mixed at different ratios. Physical and textural attributes of the products, as well as the moisture and fat contents, were measured at various frying times. Oil samples were withdrawn at different times and analyzed for colour, free fat acid (FFA) content, viscosity and dielectric properties. Physical and textural properties of chicken nuggets were influenced by frying time and the degree of oil hydrogenation. The experimental data, for changes in the properties of both flying oil and fried product, was adequately described using first order reaction kinetics. Increasing frying time decreased product lightness whereas chroma and hardness values increased. Frying in oils with higher degrees of hydrogenation resulted in products with lighter and harder (more crispy) texture. Products fried in non-hydrogenated oil absorbed more oil but also retained more moisture compared to samples fried in hydrogenated oil. The rate of change in the colour parameters of oils was observed to increase with increasing frying time and the degree of hydrogenation. The chroma values of the oils increased when frying time increased and degree of hydrogenation decreased. The viscosity of oil tended to increase with increasing degree of hydrogenation. The FFA content and dielectric constant of the frying oils correlated with frying time and degree of hydrogenation.
This paper deals with kinetics of quality changes during food frying. The quality parameters of interests include color, texture, viscoelastic properties, volume/density, and nutraceuticals (Omega 3 fatty acids). The kinetic theory and determination methodology under isothermal/non-isothermal conditions are also reviewed. This paper presents the reported reaction rate constant, order of reaction, and activation energy for specific quality changes including phenomenological observations and important speculations. The changes of color, textural, and viscoelastic properties generally followed a first order reaction. In some studies, activation energy analysis could have been improved by applying corresponding system temperatures for the quality change reactions of interest. The kinetic information on volume/density changes and thermal degradation of nutraceutical is still limited to experimental observations of the changes.
Meat is an optically anisotropic translucent tissue that may show higher reflectance when the incident illumination is perpendicular to the muscle fibers than when it is coaxial. In meat that has been washed to removed chromophores, reflectance is almost a linear function of wavelength (from about 0.3 at 420 nm to about 0.75 at 700 nm). Myoglobin (Mb) and its derivatives are primarily respon sible for selective absorbance in red meats. The Soret absorbance bands for deoxymyoglobin (DMb), oxymyoglobin (MbO2 and metmyoglobin (MMb) are at 434, 416 and 410 nm, respectively. DMb has an absorbance band at 555 nm that in MbO2) is replaced by a strong absorbance band at 578 nm and a slightly weaker band at 542 nm, although MMb formation generally masks this difference be tween reflectance at 542 and 578 nm. The relatively high myoglobin concentration of beef reduces the overall intensity of reflectance spectra to about one third of that of washed meat. Relative to the transmittance spectra of purified Mb derivatives, the reflectance spectra of intact meat are flatter, without sharp peaks, and are affected by a complex interaction between light scattering, selective absorbance and sample structure. Increases in the intensity of reflec tance spectra occur with low meat pH and with cooking. Interactance spectra obtained via optical fibers are compatible with reflec tance spectra obtained by conventional reflectance spectrophotometers provided that methods of standardization and optical geometry are taken into account.
Kinetic models for the color parameters of longissimus dorsi muscle were developed for beef carcass during chilling. Experiments were conducted to obtain the color parameters (L*, a*, and b*) during chilling. The changes in color during chilling were modeled using reaction kinetics and Eyring's absolute reaction rate theory. The derivative method was used to determine the coefficients. The color lightness followed a zero order, redness followed a first order, and yellowness followed a 0.5th order reaction. Enthalpy and entropy of activation for the color kinetics models were calculated. The enthalpy of activation was 96.3, 52.7, and 21.2 (kg mol) for lightness and redness, respectively. respectively. The entropy of activation was 0.08 and -0.08 kJ/(kg mol.K) for lightness and redness, respectively. Yellowness followed an Arrhenius relationship.
Heat and mass transfer between air and product, fried in a specially designed forced convection oven were analyzed. Minced meat loaves of an industrial recipe were fried for 1 hr at different temperatures, humidities, and velocities of the air. It was shown that the moisture loss rate was larger in the beginning of the frying than at the end. The heat transfer coefficients varied between 20 and 90 W/m2°C. These values are low compared with other frying methods. The mass transfer coefficients varied between 0.04 and 0.115 m/s. The coefficients decreased markedly in going from the constant rate period to the falling rate period.
Studies are reported on the mechanism of browning occurring in model and meat systems. When model systems were heated, brownness appeared to be due largely to the amino-sugar reaction, although some brown color development apparently occurred from caramelization of the sugars. This was shown by blocking the amino group with acylation or the carbonyl group of sugars by addition of bisulfite or hydroxylamine. The same procedures were used for studying the development of brownness in meat systems, except that in some instances the free sugars naturally present in meat were removed by yeast fermentation or by the addition of glucose oxidase. Although the data with the meat systems were not clear-cut, evidence suggested that most of the browning occurred as a result of the amino-sugar reaction. However, a small but significant amount of browning seemed to be due to pyrolysis of the natural meat sugars.
A determination of the moisture distribution in meat emulsion slab at several process times as a function of its composition and temperature, and smokehouse relative humidity, with a technique and model for determining the corresponding moisture mobility are presented. The moisture diffusivity was increasing with the decrease in the fat-protein ratio and increase in the product temperature and moisture concentration and follows an Arrhenius type relationship. The moisture profiles in the meat emulsion during processing were very steep at the product surface.
Developments in Food Preservation-2
- B. Hallstrom
- C. Skjoldebrand
Thermal Processing and Quality of Foods
- E. Holtz
- C Skjoldebrand
- A. Bognar
- J. Piekarski
Crust formation during frying of minced meat product
- C. Skjoldebrand
- Olsson H.