Optimization of Vacuum Microwave Predrying and Vacuum Frying Conditions to Produce Fried Potato Chips

The effects of vacuum microwave predrying and vacuum frying conditions on the quality of vacuum-fried potato chips were studied. Both the moisture content and oil content of potato chips decreased with increasing vacuum microwave predrying time. During vacuum frying, the moisture content of potato chips decreased with increasing frying temperature and time, while the oil content increased. Statistical analysis with response surface regression showed that the moisture content, oil content, and breaking force of potato chips were significantly (P<0.05) correlated with vacuum microwave predrying time, frying temperature, and frying time. Based on surface responses and contour plots, optimum conditions were vacuum microwave predrying time of 8–9 min, vacuum frying temperature of 108–110°C, and vacuum frying time of 20–21 min.     

Effect of low temperature on the microwave-assisted vacuum frying of potato chips

The objective of this study was to investigate the effect of low temperature on the microwave-assisted vacuum frying of potato chips. A newly built, in-house, microwave-assisted frying machine was developed and used in this study. The effect of low temperature on the microwave-assisted vacuum frying of potato chips was investigated via comparing sample properties prepared with frying temperatures of 90°C, 95°C, and 100°C. The experience was taken at the same vacuum degree in every frying process. Parameters of included moisture content, oil content, color parameters (lightness, redness, and yellowness), and textures (hardness, crispness) were used to evaluate the effect of different frying temperatures on the microwave-assisted vacuum frying of potato chips. Results showed that with lower temperature in microwave-assisted frying, the rate of moisture evaporation of potato chips was slowed down and the time of the ending of frying was prolonged from 10 min with a frying temperature of 100°C to 14 min with 90°C and 12 min with 95°C. Meanwhile, the oil content in fried potato chips was increased with lower temperature in microwave-assisted vacuum frying. The breaking force of final products are not significantly (p > 0.05) affected in different frying temperatures of microwave-assisted vacuum frying. Also, the frying temperature of 100°C in microwave-assisted vacuum frying had better preservation of natural color than the lower frying temperature with prolonged frying time. Results showed that the temperature is one of the main factors that affect the quality of microwave-assisted vacuum frying of potato chips and the producer could find suitable temperature conditions according to experience.     

Effect of Vacuum-Microwave Predrying on Quality of Vacuum-Fried Potato Chips

The effects of vacuum microwave predrying on the quality of vacuum-fried potato chips were studied. The results showed that vacuum microwave predrying had a significant effect on moisture and oil contents, as well as color parameters and structure of potato chips. Vacuum microwave predrying significantly decreased the oil and moisture contents of vacuum-fried potato chips. The rates of both mass transfer phenomena (water loss and oil uptake) that take place during the vacuum frying of potato chips decrease due to the vacuum microwave predrying. The vacuum microwave predrying had a negative effect on color of potato chips, which decreases the L value of potato chips and increases Hunter a and b values. Breaking force of fried potato chips is also significantly (P < 0.05) affected by the drying pretreatment, which decreases the breaking force at the beginning of predrying and then increases with vacuum microwave predrying time.     

Vacuum Frying of Carrot Chips

Abstract

Vacuum frying is an alternative method to produce high quality vegetable or fruit chips. The effect of frying temperature and vacuum degree on moisture content, oil content, color, and texture of fried carrot chips were investigated. During the early stage of vacuum frying, the rate of moisture removal and oil absorption increased with increasing frying oil temperature and degree of vacuum. Statistical analysis of the color data showed that there were no significant differences P > 0.05) in lightness (L), redness (a), and yellowness (b) of carrot chips as a function of vacuum degree and temperature. The breaking force of carrot chips decreased with increasing frying temperature and vacuum degree. The statistical analysis also showed that there were no significant differences P < 0.05) in the breaking force as a function of temperature, but the breaking force was significantly (P < 0.05) affected by the vacuum degree.     

Low oil content potato chips produced by infrared vacuum pre-drying and microwave-assisted vacuum frying

The effects of vacuum infrared radiation (VIR) pre-drying on the microwave-assisted vacuum frying (MVF) potato chips were investigated to study its possibility of decreasing the oil content of fried potato chips. The moisture evaporation, oil content, texture, color, surface temperature, shrinkage, and sensory analysis of fried products were evaluated. Results showed that the VIR pre-drying significantly reduced the oil content in MVF products, a decrease from 22.38 to 13.49?g oil/100?g dry solid. The application of VIR pre-drying accelerated the dehydration rate, and increased the mechanical breaking force measured with a texture analyzer with 20–30?min pre-drying. The VIR pre-drying resulted in an increase in the total color change and the shrinkage of MVF potato chips. The sensory analysis showed that the proper duration of VIR pre-drying would achieve a higher consumers’ acceptance. Comparing with the current industrial applications, vacuum frying, and atmospheric deep-fat frying, the combined VIR and MVF technology would be an alternative frying method for producing healthier fried products with less oil content and high quality.     

胡萝卜真空油炸脱水工艺和优化研究

研究了不同预处理条件哒展油炸温度、真空度、时间对胡萝卜脆片品质的影响。通过响应面分析可知：油炸温度、真空度以及时间显著影响胡萝卜片中水分与脂肪含量以及脆度（P≤0．05）;其最佳油炸工艺为温度100℃-110℃、真空度0．08—0．09MPa、时间15min。     

MODELING WATER LOSS DURING FRYING OF POTATO STRIPS: EFFECT OF SOLUTE IMPREGNATION

ABSTRACT

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.     

Antioxidative effect of olive oil deodorizer distillate on frying oil and quality of potato chips

The antioxidative effect of unsaponifiable matter from olive oil deodorizer distillate on the stability of sunflower oil during frying and on the quality of potato chips were studied. Physical and chemical characteristics of sunflower oil samples with or without different concentrations of unsaponifiable matter were examined during frying at 180°C for ten consecutive days. The addition of 1% of unsaponifiable matter to sunflower oil showed the highest effect in retarding the oxidation deterioration of oil during frying of potato chips. This protective effect was attributed to high levels of squalene, Δ-avenasterol, and tocopherols. During ten frying days, the amount of squalene decreased to 79% and both tocopherols and Δ-avenasterol to 69% in frying sunflower oil. Oil absorbed by potato chips and the characteristics of the oil extracted from potato chips before and after three months of storage were determined. The amount of oil absorbed by potato chips ranged from 37.3 to 39.3% during frying. The unsaponifiable fractions remaining in the frying medium showed protective effects on the rate of oxidation of the oil extracted from potato chips. The uptake of unsaponifiable matter by chips was the highest during the first frying day. Chips with high amounts of squalene, tocopherols, and sterols showed highest antioxidative stability during storage for three months at ambient temperature. Potato chips fried in sunflower oil treated with 1% unsaponifiable matter showed a bright yellow colour, moderate crispness, high score flavour, and were well accepted by panelists. These data of sensory evaluation supported the results of chemical analyses of oil extracted from fresh and stored chips.     

MODELING WATER LOSS DURING FRYING OF POTATO STRIPS: EFFECT OF SOLUTE IMPREGNATION

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.     

Relationship Between Oil Uptake and Water Content During Deep-Fat Frying of Potato Particulates Under Isothermal Temperature

The purpose of this study is to correlate water content and oil uptake with the structural changes of potato particulates during deep-fat frying. Raw potato particulates were sliced to form cylinders of 0.006 m diameter × 0.006 m length and subjected to deep-fat frying at isothermal oil temperatures of 160, 190 and 220 °C. The microstructure properties were assessed using a field emission scanning electron microscope (FESEM). Previous results showed that a simultaneous two first-order kinetic model adequately predicted water loss of potato particulates during isothermal frying. In this study, a simple rational model with two parameters in which regression squared (Rsqr) reaches 0.983 shows that oil uptake can be expressed by water content. The cross-sectional structure of potato particulates observed using FESEM is different from the surface structure. Regardless of the frying temperature, pores not only become larger but also increase in number after the transition time. The observations of structural changes at the surface and inner section of potato particulates through the pictures of FESEM are critical. This physical evidence supports our previous assumption that the mechanisms of water loss (two-stage rate processes) before and after transition time are different.     

Effect of fatty acid composition of oils on flavor and stability of fried foods

Effects of fatty acid composition of frying oils on intensities of fried-food flavor and off-flavors in potato chips and french-fried potatoes were determined. Commercially processed cottonseed oil (CSO) and high-oleic sunflower oil (HOSUN) were blended to produce oils with 12 to 55% linoleic acid and 16 to 78% oleic acid. Analytical sensory panels evaluated french-fried potatoes and pilot plant-processed potato chips. Initially, both foods prepared in CSO (16% oleic/55% linoleic acid) had the highest intensities of fried-food flavor; however, this positive flavor decreased with decreasing levels of linoleic acid. 2,4-Decadienal in potato chips also decreased with decreasing linoleic acid in the oils. Frying oil stability, measured by total polar compounds (TPC), and oxidative stability of potato chips, measured by volatile compounds, showed that HOSUN (78% oleic acid) produced the lowest levels of TPC and the lowest levels of hexanal and pentanal, indicating greater frying oil stability and oxidative stability of the food. However, fresh potato chips fried in HOSUN had the lowest intensities of fried-food flavor and lowest overall flavor quality. Fried-food flavor intensity was the best indicator of overall flavor quality in fresh potato chips. Volatile compounds, TPC, and oxidative stability index directly varied with increasing oleic acid, and were therefore not directly indicative of flavor quality. No oil analysis predicted flavor stability of aged potato chips. Compositions of 16 to 42% oleic acid and 37 to 55% linoleic acid produced fresh fried-food with moderate fried food flavor intensity, good overall flavor quality, and low to moderate TPC levels (chips only). However, in aged food or food fried in deteriorated oil, compositions of 42 to 63% oleic and 23 to 37% linoleic provided the best flavor stability.     

Storage Stability of Carrot Chips

Water activity combined with the glass transition temperature can be used to predict the shelf life of foods. Water sorption isotherms and glass transition as a function of moisture content were determined for carrot chips after vacuum frying. The GAB model was fitted to the measured sorption data while the Gordon Taylor equation was used to model the water plasticization effect. The critical moisture content and the critical water activity at which the glass transition occurs were obtained at selected storage temperatures. The changes in moisture content, fat content, water activity, breaking force, β-carotene content, ascorbic acid, and acid value of vacuum-fried carrot chip at selected storage temperatures (0, 10, 25°C) during a 6-month storage period were investigated. The estimated shelf life of carrot chip, defined by the degradation time of the acid value at different storage conditions, was determined.     

Freeze Drying of Apple Slices with and without Application of Microwaves

In this study, Fuji apple slices were dehydrated using freeze drying (FD) combined with microwave assisted with vacuum drying (VMD). The optimal parameter for the diversion point of moisture content from FD to VMD process was at the moisture level of 21%, and for VMD the optimal parameter for vacuum pressure was at 9.15 kPa and microwave power density was at a level of 3.18 w/g. The results show that the two-step technique can significantly reduce total FD time required by up to 40%, while the nutritional value of the dried apple chips remained unchanged compared to FD used alone.     

Effect of preconditioning on physicochemical,microstructural, and sensory quality of vacuum-fried jackfruit chips

The effect of preconditioning steps in terms of either freezing or partial drying on the quality of vacuum-fried jackfruit (JF) chips was evaluated. Prepartial drying process of the JF bulb slices resulted in the lowest moisture content in the vacuum-fried chips. The rate of oil uptake by JF bulb slices was found to be almost same in control and prefrozen samples during frying process. However, prepartial drying of slices resulted in a slower rate of oil absorption. The total carotenoid content was found to be 1.81, 0.96, and 1.87?mg/100?g (db) in control, prepartially dried and prefrozen JF chips, respectively. The Hunter L-value of control, prepartially dried, and prefrozen chips was found to be 52.3, 39.4, and 48.5, respectively. The a-value was found to increase, whereas the b-value decreased during vacuum frying in all the JF chip samples, irrespective of preconditioning type adopted. Prefrozen JF chips were found to have highest crispy texture in terms of lowest instrumental breaking force compared to the control and prepartially dried JF chips. Prefrozen JF chips were found to have lowest bulk density and highest porosity. The micrograph of prepartially dried JF chips depicted dense and shriveled structure, whereas a porous structure in prefrozen chips. The preconditioning protocols of partial drying and freezing were found to affect the overall sensory acceptability scores significantly (P?相似文献   

Vacuum Frying of Desalted Grass Carp (Ctenopharyngodon idellus) Fillets

The objective of this study was to investigate the effects of vacuum frying on the product quality of desalted grass carp fillets. Parameters of included moisture content, oil content, color values, and textures (hardness, chewiness, and springiness) were used to evaluate the product quality. Results showed that with increasing vacuum frying temperature and time, the moisture content of fillets decreased while the oil content increased, and hardness increased quickly. The hardness and chewiness values of vacuum-fried samples were both higher than those of atmospheric fried samples. However, there was no significant change in L* among four different temperature/vacuum-frying combinations. The results also indicated that vacuum frying at 0.08 MPa and 100°C–110°C for 15 min can produce crisp grass carp fillets with lower moisture and oil contents as well as good color and texture quality.     

Pore Development and Moisture Transfer in Chicken Meat during Deep-Fat Frying

Abstract

Changes in the structure of food products play important role in the various mass transfer processes during deep-fat frying. The relationship between moisture loss and pore formation were investigated at frying oil temperatures of 170, 180, and 190°C and frying times up to 900 s. Porosity and pore structure were characterized by using mercury intrusion porosimetry and helium displacement pycnometer. Moisture transfer in the samples was modeled using Fick's law and effective moisture diffusivity was computed from experimental data. Pore formation changes significantly (P < 0.01) in time as modulated by frying oil temperature. A peak pore fraction of 0.283 (after 360 s of frying), 0.238 and 0.220 (after 900 s of frying) at frying temperatures 190, 180 and 170°C, respectively was observed. Effective moisture diffusivity of 5.4 to 6.9 × 10^?9 m² s^?1 and activation energy of 20 kJ/mol was obtained for the frying oil temperatures. Changes in pore structure influenced moisture diffusivity and oil uptake. Eighty-four percent of the pores are capillary pores, hence moisture transfer increased.     

Drying Characteristics and Quality of Restructured Wild Cabbage Chips Processed Using Different Drying Methods

The drying characteristics of restructured wild cabbage chips dried using microwave vacuum (MVD), hot air (AD), and microwave freeze drying (MFD) were compared. Some of the key quality parameters of restructured wild cabbage chips such as fracturability and color and sensory characteristics were measured. Results showed that the drying time was reduced with the increase of microwave power (MVD/MFD) and in the case of air drying by the temperature (AD). Drying time was the shortest in the MVD process. Optimal quality of dried chips was obtained with the MFD process at a microwave power level 2.0 W/g.     

Optimization of Osmotic Dehydration of Potato Cubes Under Pulsed Microwave Vacuum Environment in Ternary Solution

Optimization of the process parameters for osmotic dehydration of 12.2-mm potato cubes was carried out using response surface methodology. The experiments were conducted using a central composite rotatable design (CCRD) with four factors, viz. sucrose concentration (27.5–42.5% w/w), salt concentration (7.5–12.5% w/w), total osmosis time (26.25–68.75 min), and microwave power density for the initial 4 min (0.375–1.125 W/g of total weight of solution and potato cubes) at two levels each to take into account the individual and interaction effects of the factors. A sample-to-solution ratio of 1:10 and pressure of 0.16 kPa for the initial 4 min were kept constant throughout all of the experiments. It was found that the linear effects of all factors on the water loss (WL) and solids gain (SG) were highly significant. The optimum condition was found at a sucrose concentration of 36.35%, salt concentration of 12.50%, osmosis time of 68.72 min, and microwave power density of 0.38 W/g for the initial 4 min, with a WL of 37.26% initial weight and SG of 8.74% initial weight. The drying of potato cubes was carried out using hot air, microwave–vacuum, and osmotic microwave–vacuum drying methods. It was found that potato cubes dried by combined osmotic microwave–vacuum had better sensory qualities.     

Ultrasonically enhanced low-temperature microwave-assisted vacuum frying of edamame: Effects on dehydration kinetics and improved quality attributes

Abstract

Using ultrasound (US) at microwave-assisted vacuum Frying (MVF) program was investigated to acquire better process efficacy and bodily high-quality attributes of fried edamame. Different power degrees of US (0, 150, 300, 600 W) and temperature (80, 90, and 100?°C) were utilized in a constant microwave power and frequency of 1000 W and 28?kHz during ultrasound and microwave-assisted vacuum frying (USMVF) process. Ten different mathematical models were employed to describe dehydration kinetics of the fried edamame, and nonlinear regression analysis was used to determine model parameters. Concerning fitting performance, the most suitable model was the two-term model. Drying kinetics, effective moisture diffusivity (D_e), activation energy (E_a), and physical properties of fried samples were evaluated in this newly designed USMVF equipment using different ultrasound power to the studied temperature range. By increasing the US power level, the calculated D_e increased from 1.947?×?10^?9 to 4.742?×?10^?9 m²/s. The results have revealed that the E_a of this fried edamame decreased significantly with increasing the US power level. The USMVF process at every frying temperature increased the drying kinetics and D_e when compared to the non-USMVF process. The USMVF samples always gave lower oil content and water activity in contrast to the non-USMVF samples. The color and texture properties of fried edamame were significantly improved and higher the US power level in the USMVF produced a better progress. Vitamin C and chlorophyll retention of fried edamame was highest in US600MVF process.     

Effect of Various Pretreatments on the Quality of Vacuum-Fried Carrot Chips

Carrot slices were subjected to the following four different pretreatments prior to vacuum frying: (1) blanching, (2) blanching and air drying, (3) blanching and osmotic dehydration, (4) blanching, osmotic dehydration, followed by freezing. The effects of these pretreatments on the physicochemical properties and fat distribution in vacuum-fried carrot chips were also investigated. There were significant differences in the total yield, amounts of carotenes, vitamin C, and the color values of carrot chips following different pretreatments (P < 0.05). Pretreatment significantly affected the water content, fat content, and water activity of carrot chips (P < 0.05), while there were no significant differences in the breaking force of carrot chips treated with different pretreatments (P > 0.05). Spearman correlation analysis showed a high positive correlation between the fat content of carrot chips and the initial water content of carrot slices. The fat distribution pattern depended on the initial water content and the structure of the material left by water evaporation.