Effects of processing conditions on the quality of vacuum fried apple chips

The effects of pretreatment and processing conditions on the quality of vacuum fried apple chips were studied. As blanched apple slices were pretreated by immersing in fructose solution and freezing prior to vacuum frying, more uniform porosity was observed on the surface (or cross-section) of apple chips as examined by scanning electron microscopy (SEM). During vacuum frying, the moisture content and breaking force of apple chips decreased with increasing frying temperature and time while the oil content increased. The L values of fried apple chips decreased apparently with increasing frying temperature. However, when apple slices were fried at 100°C for up to 20 min, both a and b values increased rapidly. Statistical analysis with the central composite rotatable design showed that the moisture content, oil content, color, and breaking force of apple chips were significantly (P⩽0.05) correlated with concentration of immersing sugar solution, frying temperature and frying time. Based on surface responses and contour plots, optimum conditions were: vacuum frying temperature of 100–110°C, vacuum frying time of 20–25 min, and immersing fructose concentration of 30–40%.     

Optimization of Blanching Conditions Prior to Deep Fat Frying of Yam Slices

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.     

Application of Vacuum Frying as a Furan and Acrylamide Mitigation Technology in Potato Chips

Consumers like fried snacks, and taste, color, and texture are key aspects in their preference. However, during frying of foods some toxic compounds, such as furan and acrylamide, are produced. The objective of this work was to mitigate furan and acrylamide formation in potato chips, without affecting their main quality attributes, by using vacuum frying. To accomplish this purpose, potato slices were fried at atmospheric (P _abs 29.92 inHg) and vacuum conditions (P _abs 3.00 inHg), using equivalent thermal driving forces (T _{water boiling point} ? T _oil = 50, 60, or 70 °C). Furan and acrylamide concentration, oil content, and texture of both atmospheric and vacuum-fried samples were determined. Vacuum-fried potato chips showed reductions of about 81, 58, and 28% of furan, acrylamide, and oil content, respectively, when compared to their atmospheric counterparts. Additionally, the texture was not affected (p > 0.05) by changes in the pressure during frying. Results clearly showed that vacuum frying is an effective technology for furan and acrylamide mitigation in potato chips, since it reduces the content of both contaminants and preserves the quality attributes of fried snacks.     

Microwave Frying Compared with Conventional Frying via Numerical Simulation

Microwave heating can be combined with other means of heating to yield a unique heating profile. In the study, microwave frying, a combination of convective and microwave heating, was compared with conventional frying. Frying experiments were performed by inserting a single food sample (chicken breast meat) in the hot oil at 180?±?1°C for both frying methods. Center temperature of the sample and the oil temperature were recorded during both frying methods. Simulations were performed to predict heat transfer coefficients. Processing time was shorter with microwave frying. Simulations revealed a varying convective heat transfer coefficient, which was in the range of 160–490 W/m² K, during conventional frying. Higher convective heat transfer coefficient, 500 W/m² K, compared to conventional frying was observed during microwave frying with the simulations. This is suggested to be due to higher turbulence in microwave frying.     

The Effect of Methylcellulose,Temperature, and Microwave Pretreatment on Kinetic of Mass Transfer During Deep Fat Frying of Chicken Nuggets

The aim of this study was to determine the effect of microwave pretreatment, usage of methylcellulose, oil temperature, and frying time on mass transfer during deep fat frying of chicken nuggets. Methylcellulose was used in batter and as a coating on product. Microwave with two power densities namely 3.7 and 7.4 W/g was used for reduction of initial moisture content of samples before frying. Frying was performed at three temperatures (150 °C, 170 °C, and 190 °C) and five intervals (0.5, 1, 2, 3, and 4 min) in the sunflower oil. The least oil content was observed when MC was used as a coating layer on non-precooked samples fried at 190 °C. Oil absorption of samples with MC in batter was partially higher compared to control samples. This could be attributed to the rheology of batters. The first-order kinetic model was fitted to moisture and oil content. For determining the correlation between temperature and moisture diffusivity, Arrhenius equation was used. The constant rate for moisture and oil transfer was in the range of 2.2–5 and 0.023–2.67 s^?1, respectively. Effective moisture diffusivity values were between 1.43?×?10^?8 and 3.24?×?10^?8 m²/s. Activation energy ranged between 0.71 and 1.71 kJ/mol.     

Effects of Initial Moisture Content on the Oil Absorption Behavior of Potato Chips During Frying Process

During frying process, whether and how moisture content in materials affects oil absorption remain unclear. Herein, we provided direct evidence suggesting that although the initial moisture content had no significant effect either on the final oil content or oil fraction, the moisture content did greatly affect the rate of oil absorption. We analyzed the total oil (TO), surface oil (SO), structural oil (STO), penetrated surface oil (PSO), and oil distribution during frying process in once-fried and twice-fried potato chips, and found that SO fraction was lowest (about 0.90-1.66 %) among three different fractions of TO, while PSO was the dominant section (about 50 %) for TO. Surprisingly, there were no significant difference among the final TO, SO, STO, and PSO for two kinds potato chips (P > 0.05), a finding suggesting that the initial moisture content itself might have no effect on oil absorption. Compared with once-fried potato chips, twice-fried chips much quicker (around sevenfold) reached equilibrium at 180 °C, which might be attributed to no inner resistance of water evaporation in twice-fried potato chips. More importantly, our confocal laser scanning microscopy (CLSM) inspection established that oil of twice-fried chips entered the core faster than once-fried chips. Oil followed the cell shapes and located in cell walls and inside the intercellular spaces for both samples. Taken together, this study provided compelling new data to clarify the relationship between the initial moisture content and oil absorption during frying process, and laid the groundwork for introducing a pre-drying strategy to frying process in food industry.     

Optimization of processing conditions for vacuum frying of high quality fried plantain chips using response surface methodology (RSM)

Optimization of processing conditions (temperature 122 to 136°C, vacuum pressure 9.91 to 19.91 cmHg, and frying time 3 to 9 min) during vacuum frying of plantain chips was investigated using a Box-Behnken experimental design with response surface methodology (RSM). Models for various responses were developed and optimized frying conditions using numerical solutions were established. Optimized vacuum fried samples were compared with atmospheric fried samples based on the concept of equivalent thermal driving force (ETDF). Frying parameters had significant (p<0.05) effects on the moisture content, texture, and color with a coefficient of determination (R ²) for quadratic model responses varying between 0.53 and 0.99. Optimum vacuum frying conditions for plantain chips were a frying temperature of 133°C, vacuum pressure of 9.91 cmHg, and frying time of 6 min based on desirability concepts. Vacuum fried plantain chips had more acceptable sensory properties, based on ETDF values, than atmospheric fried samples.     

Frying Oil Temperature: Impact on Physical and Structural Properties of French Fries During the Par and Finish Frying Processes

The physical, mechanical, and structural changes in French fries at different frying temperatures (170, 180, and 190 °C) during par and finish frying were investigated. The experimental frying process includes blanching, par frying, freezing, and finish frying at the point of consumption. Par frying temperature had a greater effect on moisture reduction than on processing time with the greatest moisture loss at 180 °C after 160 s. At 180 °C, fries had the highest total oil uptake (29.56 % wb). Frying caused a significant change in color with the greatest effect at 190 °C. Micro-CT scan images showed structural changes in French fries over the course of the frying process. Frying time increased the volume of the pores relative to the size of the crust, and this was positively correlated with the hardness and shear cutting force. Overall, within the range of frying conditions studied, the higher temperature (190 °C) resulted in the lowest amount of oil uptake and the crispiest texture.     

Hollow Fiber Liquid Phase Microextraction Method Combined with High-Performance Liquid Chromatography for Simultaneous Separation and Determination of Ultra-Trace Amounts of Naproxen and Nabumetone in Cow Milk,Water, and Biological Samples

A simple and highly sensitive method based on hollow fiber liquid phase microextraction combined with high-performance liquid chromatography and fluorescence detection has been developed for simultaneous separation, preconcentration, and determination of naproxen and nabumetone from water, wastewater, milk, and biological samples. Parameters affecting the microextraction efficiency were evaluated and optimized. Under optimum conditions (extractant (14 μL of 1-undecanol), sample pH (3.0), extraction time (20 min), stirring rate (600 rpm), temperature (45 °C), potassium chloride concentration (4.0 %) and sample volume (9 mL)), the limits of detection based on (S/N?=?3) were 1.3 ng L^?1 for naproxen and 2.9 ng L^?1 for nabumetone. The intra- and inter-assay relative standard deviations for naproxen and nabumetone were in the ranges of 3.2–6.1 % and 6.5–9.5 %, respectively. The calibration curves were linear in concentration ranges of 4.0–300.0 ng L^?1 and 9.0–300.0 ng L^?1 for naproxen and nabumetone, respectively, with good coefficient of determination (r ²?>?0.999). The method was successfully applied to the determination of naproxen and nabumetone in cow milk, water, wastewater, human plasma, and urine samples.     

Shrinkage of Chicken Nuggets During Deep-Fat Frying

Apparent density and apparent volume shrinkage of chicken nuggets were analyzed at three frying temperatures (160, 170, and 180°C) at 16 time intervals between 0 and 300 s. A linear relation was found for particle densities with moisture loss. Apparent density decreased from about 1080 to 980 kg/m³ during frying. The regression of volumetric shrinkage as a function of moisture loss gave coefficient of determination value (R²) values ranging between 0.90 and 0.94. Temperature effect on apparent density was not significant, while its effect on shrinkage was quite pronounce (P < 0.05). The influence of moisture loss, frying time and temperature on density and shrinkage during deep-fat frying of chicken nuggets was established.     

Effect of Microwave Frying on Acrylamide Generation,Mass Transfer,Color, and Texture in French Fries

The objective of this work was to evaluate the effect of microwave power on acrylamide generation, as well as moisture and oil fluxes and quality attributes of microwave-fried potatoes. Concretely, 25 g of potato strips, in 250 mL of fresh oil (at room temperature), were subjected to three different microwave powers (315, 430, and 600 W) in a conventional microwave oven. Microwave frying resulted in an acrylamide reduction ranged from 37 to 83% compared to deep-oil frying. Microwave-fried French fries presented lower moisture and higher fat content than deep-oil fried potatoes. Concretely, microwave-fried potatoes presented values of moisture and texture more similar to potato chips than French fries, nonetheless with lower fat levels (less than 20 g/100 g wb) and acrylamide content (lower than 100 μg/kg wb) at the reference time. This study presents an alternative way of frying to address the production of healthier potato chips.     

The optimization of vacuum frying to dehydrate carrot chips

The effects of pretreatment and processing conditions, such as frying temperature, absolute vacuum pressure and frying time; on the properties of fried carrot chips were studied. Statistical analysis with response surface regression showed that moisture content, fat content and breaking force of carrot chips were significantly (P < 0.05) correlated with frying temperature, vacuum absolute pressure and frying time. The optimum conditions were a vacuum frying temperature of 100–110 °C, a vacuum absolute pressure of 0.010–0.020 MPa and a frying time of 15 min.     

Effects of processing conditions on the quality of vacuum‐fried carrot chips

The effects of pretreatment and vacuum frying conditions on the quality of fried carrot chips were studied. The moisture and oil contents of fried carrot chips were significantly (p < 0.05) reduced when blanched carrot slices were pretreated by immersion in fructose solution and freezing prior to vacuum frying. Furthermore, more uniform porosity was observed on the vertical cross‐section of carrot chips when examined by scanning electron microscopy. During vacuum frying, the moisture content, colour and breaking force of carrot chips decreased while the oil content increased with increasing frying temperature and time. However, there was no apparent change in Hunter ΔE with time when the frying temperature was below 100 °C and the frying time was below 25 min. Results of this study suggest that vacuum frying at moderate temperature (90–100 °C) for 20 min can produce carrot chips with lower moisture and oil contents as well as good colour and crispy texture. Copyright © 2005 Society of Chemical Industry     

A Kinetic Study of Furan Formation in Wheat Flour‐Based Model Systems during Frying

Furan is a possible human carcinogen, which is formed in worldwide highly consumed fried starchy foods. In order to elucidate the mechanisms responsible for its occurrence in this food category and propose techniques for its mitigation, the kinetics of furan formation, oil absorption, lipid oxidation, and color change were studied in wheat flour‐based model systems during frying at 160, 170, 180, and 190 °C up to 13 min and data were fitted to mathematical models. Additionally, an Arrhenius‐type dependency with temperature was evaluated for all studied responses. More drastic frying conditions increased significantly (P ≤ 0.05) the furan content of fried samples. Furan formation followed a sigmoid trend with frying time only for frying temperature of 190 °C (RMS_190°C: 7.6%). At lower temperatures, furan generation did not reach the asymptotic concentration level. Color change, lipid oxidation, and oil absorption increased with frying temperature and followed asymptotic relationships with frying time. For all evaluated temperatures, color change (RMS: 4.4% to 12.5%) and polar compound generation (RMS: 2.6% to 7.4%) presented good fit to a first‐order kinetic model. Oil absorption was successfully fit to a mass balance‐based model (RMS: 10.0% to 19.8%). Under the experimental conditions studied, only color change (E_A: 15.47 kJ/mol), lipid oxidation (E_A: 6.67 kJ/mol), and oil absorption (E_A: 76.98 kJ/mol) presented good fit (RMS: 0.7% to 6.3%) to an Arrhenius‐type equation. Based on our results, the keeping of frying temperature below 180 °C and the reduction of the frying time would contribute to reduce not only the final furan occurrence in fried foods but also their oil content.     

Color changes and acrylamide formation in fried potato slices

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 a¹. 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 a¹ in the range of the temperatures studied.     

Thermal degradation kinetics of anthocyanins from Chinese red radish (Raphanus sativus L.) in various juice beverages

Thermal and storage stabilities of red radish anthocyanins (RRAs) in various juice beverages (apple, grape, peach, pear, pomegranate and lemon) were studied over temperature range 70–90 °C and 4–25 °C. RRAs degradation in all juice beverages followed first-order reaction kinetics. RRAs showed a much faster degradation rate during storage at room temperature (t _1/2 value ≤84.0 days) than did in refrigerated temperature (t _1/2 ≥value 130.9 days). The rate constant (k), E _a and Q ₁₀ values for RRAs in juice beverages varied from 1.33 to 0.33, 47.94 to 14.77 kJ mol^?1 and 1.16 to 1.89 at 70–90 °C. During heating, RRAs in peach and pomegranate showed higher stability than others at these temperatures. There was a positive correlation (R ² > 0.9128) between ascorbic acid content of juice beverages (8–36 mg/100 mg) and stability of RRAs at 70–90 °C. It was found that RRAs in apple and pear juice beverage were more stable than in other juice beverages.     

Effects of deep‐fat frying temperature on antioxidant properties of whole wheat doughnuts

The total phenolic (TP) content, phenolic acid composition and in vitro antioxidant capacity of whole wheat doughnuts fried at 120–180 °C were determined to identify the effects of frying temperature. Significant differences (P < 0.05) in TP content were observed between doughnuts fried at different temperatures. The TP content of doughnuts decreased significantly when doughnuts were deep‐fat fried. The TP content of doughnuts increased with elevation with frying temperatures. These increases in TP content of doughnuts were also detected in the determination of individual phenolic compounds using HPLC. DPPH radical and iron‐chelating capacity of deep‐fat fried doughnuts exhibited increases with elevation of frying temperature from 120 to 180 °C. Deep‐fat frying at 120 °C lowered lipid peroxidation inhibition capacity of doughnuts prepared from both refined flour and whole‐grain meals and increased consistently with increased frying temperature from 120 to 180 °C. Moderate deep‐fat frying temperature would increase the content and activity of antioxidants of doughnuts.     

Yields, Color, Moisture and Microbial Contents of Chicken Patties as Affected by Frying and Internal Temperatures

Frozen, raw, battered and breaded chicken patties were tempered to an internal temperature of 1.1 ± 0. 1°C. The patties were fried to three different internal temperatures (48.9°, 60.0° and 71.1°C) in each of three shortenings preheated to 168.3°, 179.4°, and 190.6°C. Yields and selected quality characteristics of the patties were measured. At the same internal cooking temperature, frying yield and moisture content of the patties were not different (P > 0.05). Higher frying temperature and longer frying time yielded lower Hunter “L” values and a tendency to produce higher Hunter “a” values. An interaction between frying temperature and internal temperature was significant for microbial counts. No difference (P > 0.05) in microbial count was observed when patties were fried to an internal temperature of 60.0° or 71.1°C.     

Effects of Added Phenolics on the Lipid Deterioration and Antioxidant Content of Deep-Fried Potato Fritters

The health benefits of phenolic antioxidants justify their inclusion in foods like deep-fried potato fritters that are exposed to high heat during processing. In this study, phenolic antioxidants [quercetin, rutin or an apple phenolic extract (APE)] were incorporated into batters that were subsequently used in the preparation of deep-fried potato fritters. The fritters were deep fried at 180 °C for 2.5 min or 165 °C for 3 min using fresh or used canola oil. The study aimed to investigate the effect of added phenolic antioxidants on the lipid deterioration during deep frying potato fritters. The effectiveness of these phenolics against lipid deterioration was also examined for the potato fritters that have been left in the air at room temperature for 0.5 or 1 h after deep frying. The total oxidation (Totox) value (based on the peroxide value and p-anisidine value) and free fatty acid content of the oil extracted from the deep-fried potato fritters, as well as the total extractable phenolic content, of the fritters were evaluated. Results showed that APE, quercetin and rutin suppressed oil deterioration to different extents, and their effectiveness was influenced by deep-frying conditions, the number of times the oil had been used and the time period that the fritter was exposed to the air after deep frying. For the fresh or singly used oil, the recommended deep-frying parameters are 180 °C for 2.5 min (“high heat short time” approach). For oil used more than once, deep frying of potato fritters at 165 °C for 3 min (“low heat long time” approach) is generally recommended. Adding phenolics to the batter used for making potato fritters before deep frying increases product nutritional value and reduces oil oxidation, which indicates the feasibility of producing healthier potato fritters.