Frying Time Research Articles

Deep Fat Frying Characteristics of Malpoa: Kinetics, Heat, and Mass Transfer Modeling

This article investigated deep-frying characteristics of malpoa for varied frying time (2–10 min) and temperature (170–190 °C). The evaluation encompassed a comprehensive analysis of textural and color kinetics and heat and mass transfer modeling during deep fat frying of malpoa balls. Such investigations confirmed an enhancement in fat content from 10.2 to 41.65%. On the other hand, textural properties such as hardness, cohesiveness, and springiness varied from 3.14 to 22.59 N/mm, 0.22 to 0.76, and 15.5 to 49.56, respectively. Similarly, color parameters such as b*/a* and ΔE varied from 3.31 to 1.55 and 55.36 to 75.48. For the textural and color kinetics, the activation energies ranged between 58.65 and 85.82 kJ/mol and 31.34 and 64.34 kJ/mol. Similarly, for a variation in frying time from 2 to 10 min, responses (hardness, cohesiveness, springiness, and overall color) varied across the following ranges: 3.15–13.57 N, 0.22–0.66, 15.5–35.5, and 55.63–63.50 and 5.60–20.60 N, 0.30–0.77, 22.35–49.56, and 62.26–75.65 for temperatures of 170 and 190 degrees, respectively. On the other hand, heat and mass transfer analysis indicated a Biot number and heat transfer coefficient within the range of 0.31–0.65 and 25.58–34.64 for 170–190 °C. Thus, this investigation provides a deeper insight of the deep fat frying characteristics of malpoa. This provides a guideline for the food processing sector for such products.

Prediction acrylamide contents in fried dough twist based on the application of artificial neural network

Acrylamide forms through the reaction between reducing sugars and asparagine in the thermal processing of food. Detection measures like LC-MS, HPLC are time-consuming and costly, which inspired us to use back propagation-artificial neural networks (BP-ANN) based on a genetic algorithm to establish an acrylamide prediction model in fried dough twist. The effects of frying time and temperature on acrylamide contents, as well as the color difference and acid value at different time and temperature were determined. Acrylamide content was found significantly correlated with temperature (P < 0.01) and was correlated with acid value and color difference (P < 0.05). Thus, temperature, acid value, and the color difference were set as input layers, and acrylamide content was set as an output layer to establish a BP-ANN network prediction model. The weight and threshold values in the BP-ANN network prediction model were optimized with a multi-population genetic algorithm and the test data were set to obtain an optimized BP neural network predicting model. The results showed that the Levenberg-Marquardt back-propagation training algorithm of the BP-ANN model with 5 hidden layer neurons and 0.005 learning rate was the best predictive performance, which the correlation coefficients (R) of test and validation were 0.9640 and 0.8999, suggesting a good fitting and strong approximation ability. The BP-ANN model is expected to accurately predict the content of acrylamide in fried dough twist.

Effect of Gradient Vacuum Pressure on Quality Parameters of Vacuum‐Fried Bananas Chips

ABSTRACTThe effect of vacuum pressure mode has not been studied depth yet. Effect of vacuum pressure on the quality of vacuum‐fried banana slices was studies in this work. Three vacuum frying processes were conducted and tested. Classically, two constant vacuum pressures 80 (CVF‐80) and 180 mmHg (CVF‐180) were applied in the frying process at 90°C. One novel frying method with gradient vacuum pressure (GVF) changed from 760 to 80 mmHg was conducted and adapted. The frying temperature was kept at 90°C. The frying processes were monitoring by moisture contents and 4% was generally accepted as moisture content of final product. Meanwhile, the frying times of CVF‐80, CVF‐180 and GVF were 50, 80 and 60 min, whereas the brightness values (L*) were corresponded to 71.07, 71.36, 67.25, respectively. The GVF samples were brightest with lowest hardness value (30.8 N) and the CVF‐180 was darkest with highest hardness value (36.87 N). The microstructure analysis showed that the GVF increase in both size and number of pores in comparison with CVF. Additionally, based on the paired comparison sensorial test the GVF fried banana slices were crisper than CVF samples. Our results revealed that the GVF method improves the quality of vacuum‐fried banana slices, thus it can be good alternative method for production of banana snack.

Quality of Reused Frying Oils from Various Fried Food Vendors in Ho Municipality

Background: Frying makes food tasty; therefore, most people prefer the intake of fried foods to unfried foods. Oil for frying is mostly used again due to cost, and this can pose health hazards to the consumer. The aim of this study was to evaluate the quality of reused frying oils. Methods: Twenty samples of reused oils collected from fried food vendors in May 2021. Using an experimental study, the samples were analysed and Peroxide, Free Fatty Acid (FFA), Saponification, Iodine Values as well as rancidity and beta carotene were determined. Data from laboratory assays were analysed with Microsoft excel 2013 and SPSS v.26.0. Results: Moisture content was observed to decrease as median from 1.19% (0.20-4.04%) for oils reused after a day to 0.60% for oils reused after 2 days with a significant effect (p-value=0.049), indicating that the quality of reused frying oil was affected by repeated use. The moisture content was also observed to be higher in oils in which plant products were fried compared to those in which animal products were fried. The Peroxide Value was recorded as 16.80 (5.80-55.80) and 21.90 (11.50-32.30) mEq/kg for oils with 10-20 and 21-40 min frying times, respectively; whilst their moisture content decreased from 0.97 (0.19-2.55) to 0.68% (0.60-0.77%) for 10-20 and 21-40 min, respectively. The authors also observed that factors such as the duration of reuse and storage after frying, conditions of storage, type of food fried in the oil, and the period of frying per food batch impacted the quality attributes of the reused oils. The FFA composition for instance increased with the duration of use of the oils. Furthermore, oils stored in plastic bottles recorded higher FFA values compared to those stored in frying pans. Conclusion: The findings show the need for fried food vendors to reduce the duration of storage of reused frying oil, and avoid storage conditions that expose oils to excess light. Also, the development of quality standards for highly patronised oils needs to be established to ascertain the impact of low-temperature long-time and high-temperature short-time treatments of the oils among non-existent jurisdictions.

Assessing textural changes of breaded deep‐fat fried chicken nuggets during post‐frying holdings under infrared heat‐lamp using acoustic‐mechanical techniques

SummaryTexture is a multi‐parameter attribute and one of the prime quality attributes of fried products. This study examined the influence of post‐frying holdings under a heat lamp on the texture of breaded fried chicken nuggets. Chicken nuggets were deep‐fat fried (2, 4, 6, and 8 min) in canola oil at 180 °C. The fried samples were kept under an infrared heat lamp for up to 1 h, and the textural characteristics were compared with samples not exposed to post‐frying holdings. Textural characteristics were analysed through mechanical‐acoustic approach. The mechanical‐acoustic parameters related to crispiness analysed included maximum force (Fmax, N), number of force peaks (NFP), the area under force‐deformation curves (AF, N.sec), sound pressure level (SPL, dB), number of sound peaks (AUX) and the area under the amplitude‐time plots (AS, dB.sec). The mechanical parameters (Fmax: 19.11–48.96 N; NFP: 5–40; AF: 43–135 N.sec) of chicken nuggets increased with frying time, and these attributes were decreased during post‐frying holding. Similarly, acoustic parameters (SPL: 64.75–90.67 dB; AUX: 180–795; AS: 63–98 dB.sec) of chicken nuggets increased with frying time, and these attributes were decreased during post‐frying holding. Considering the studied parameters, 6 min of frying was found as optimal frying time. However, the post‐frying infrared heat lamp treatment affected the mechanical textural parametres more than the acoustic parameters. Findings from this study will be useful to food industries in optimising textural retention during post‐frying heat lamp holdings of fried products.

Unravelling the nexus between structure, texture, and acoustic traits of fried chicken nuggets

SummaryTexture is a multi‐parameter attribute and one of the prime quality attributes of fried products. This study explored the nexus between microstructure and texture of fried breaded chicken nuggets. Chicken nuggets were deep‐fat fried (2, 4, 6, and 8 min) in canola oil at different frying temperature (170, 180, and 190 °C). Microstructure and texture of fried samples were assessed by scanning electron microscopy (SEM) and acoustic‐mechanical texture analyser, respectively. Maximum force (Fmax), number of force peaks (NFP), area under force‐deformation plots (FA), sound pressure level (SPL), number of sound peaks (AUX), and area under amplitude‐time curves (SA) were used to describe the textural parameters. Microstructural indices (porosity, number of pores, average pore area, polydispersity index, and average shape factor) were estimated from the SEM images. Results revealed that, both the frying time and temperature were positively correlated with the mechanical (Fmax: 25–55 N, NFP: 05–74 N, FA: 6500–15 000 N.sec) and acoustic (SPL: 88–97 dB, AUX: 650–810 dB, SA: 380–405 dB.sec) parameters. Frying time and temperature significantly (P &lt; 0.05) impacted the formation of micropores in fried chicken nuggets. Crust microporosity showed strong positive correlations (r = 0.82) with the AUX value. The NFP, SPL, and SA of the fried nuggets were significantly (P &lt; 0.05) impacted by the crust microporosity. Crust porosity (10–30%), number of pores (8–400), average pore area (10–4000 μm2), polydispersity index (0.05–0.2), and average shape factor (0.8–1.1) of fried nuggets were significantly (P &lt; 0.05) influenced by both the frying time and temperature. Findings from this study would be useful in quality improvement and process monitoring including modelling of coated fried products.

Waste Point Identification of Frying Oil Based on Gas Chromatography-Ion Mobility Spectrometry (GC-IMS).

This study described the quality detection and rapid identification of frying oil waste points based on gas chromatography-ion mobility spectrometry (GC-IMS). A total of 48 volatile substances were identified, among which the levels of 11 components, including 2-pentylfuran, 2-butylfuran, and 2-hexanone, increased with prolonged frying time after 40 h in cottonseed oil. Conversely, the levels of hexanal, heptanal, and E,E-2,4-heptadienal decreased as frying time extended. Correlation analysis revealed a significant association between volatile substances of the oil and acid value (p < 0.05) and polar components with volatile substances (p < 0.05). Furthermore, significant differences in the types and contents of flavor substances were observed in cottonseed oil at different frying times (including before and after reaching the discard point) (p < 0.05). Subsequently, principal component analysis (PCA) results clearly showed that the cottonseed oil samples at different frying times were well distinguished by the volatile compounds; moreover, discriminant model analysis indicated a model accuracy rate of 100%. These results showed the potential of GC-IMS-based approaches in discriminating the waste points of frying oil.

Effect of basil seed gum coating and ultrasound pretreatment on frying time, oil uptake, hardness, color indexes, and sensory properties of potato slices

Fried food products have low oil content with improved nutritional quality, higher crispiness, and better sensory attributes. Edible coatings can decrease the excessive oil uptake in deep-fat fried food products. Furthermore, ultrasound treatment before frying process decreased oil uptake of food products. So, in this study, the impact of gum edible coating and ultrasonic pretreatment (at two different power levels of 75 and 150 W) on the frying time of potato slices, and moisture percent, oil uptake, texture hardness, surface area change, color parameters (lightness, redness, yellowness, and total color change), and sensory attributes of fried potato slices were examined. Edible coating with basil seed gum (BSG) and ultrasonic pretreatment significantly increased the frying time of the slices (p < 0.05). The average moisture content of the fried slices changed from 49.48 % to 60.55 %, and was further increased by edible coating and ultrasonic treatment. The highest (26.92 %) and lowest (14.56 %) oil uptake were for the uncoated and coated-sonicated (150 W) fried potato slices, respectively. The ultrasound pretreatment significantly increased the hardness of fried potato slices (p < 0.05). The low and high intensity ultrasonic pretreatment (75 W and 150 W, respectively) significantly decreased the crust area change of fried potato slices (p < 0.05). The average lightness index of the fried samples changed from 63.30 to 71.58, and increased with increasing ultrasonic power. The minimum redness, yellowness, and total color change indexes were for the coated and high-power sonicated (150 W) samples, respectively. The highest appearance, odor, texture, flavor, and overall acceptance were for the coated and high-power sonicated (150 W) sample.

Sunflower oil‐soybean wax oleogel: An oxidation stable alternative to traditional frying methods for doughnut

AbstractDeep‐frying changes the quality of the oil through hydrolysis, oxidation, and polymerization, which makes both positive and harmful changes in the oil and fried food items. In this study sunflower oil was combined with soybean wax to create oleogels that were assessed for their ability to reduce fat uptake and maintain oxidative stability during the deep‐fat frying of doughnut samples. The oleogel was tested as a potential alternative to traditional deep‐fat frying with sunflower oil for frying doughnuts. The different frying times of oleogel were examined to assess the physical properties of the oleogel. Afterward, a comparative analysis was conducted between doughnuts fried in sunflower oil and oleogel. The results showed that doughnuts fried in oleogel absorbed approximately 37.8% less oil than those fried in sunflower oil. Additionally, the doughnuts fried in oleogel had a better appearance, with a higher lightness value (L*) (87.73 ± 0.8) than those fried in oil (77.72 ± 1.35). Moreover, the redness value, (a*) of oleogel doughnuts was also lower (0.33 ± 0.25) than those fried in oil (0.37 ± 0.9). The blueness or yellowness (b*) of the doughnuts was not significantly different which was found as 1.52 and 1.54, for oleogel and oil samples, respectively. Although the viscosity values of oleogel were higher during extended frying, the lower peroxide, free fatty acid, p‐Anisidine, conjugated diene, and triene values suggest that oleogel is more stable. These results will provide a significant advantage in the usage of sunflower oil‐soybean wax oleogel as a frying medium with improved stability.

Optimizing Process Conditions for Ghewar Development Using Response Surface Methodology

RSM was performed for the optimization of processing conditions to develop ghewar, traditional sweetmeat of India. Three variables i.e. frying temperature (160-180 ⁰C), batter temperature (5-10 ⁰C) and frying time (4-6 minute) were taken to investigate the effect on ghewar responses viz., oil content, moisture content, texture and sensory attributes (OA). The optimum conditions were 160 ⁰C frying temperature, 5⁰C batter temperature and 4 minute frying time. Upon optimization, the ghewar yielded the following results: 45.33% oil content, 4.65% moisture, 15.2 N texture (hardness), 54.89 L value, 15.16 a value, 24.97 b value, 58.73 hue value, 29.21 chroma value, 48.07 total color difference, and 0.24 water activity. Storage study of optimized ghewar was also carried out and found shelf stable for 30 days in metallised foil pouches. Hardness values were found to progressively drop from 15.2-9.40 N during the storage period, whereas moisture content, FFA, and peroxide value were found to gradually increase from 3.70-5.12%, 0.33-0.54 %, and 4.8-7.6 meq/kg, respectively.

The impact of pre-drying and different infrared powers on some quality parameters of apple chips fried by vacuum-combined infrared radiation

In this study, the use of vacuum-combined infrared radiation (VCIR) as a frying technique for the production of apple chips was investigated. The effects of a pre-drying treatment before frying on the quality parameters of apple chips were also evaluated. While the frying time of apple slices decreased by increasing the infrared power, the browning index value, 5-hydroxymethylfurfural (HMF) content, and oxidation ratio were raised. The frying times, oil contents, browning, and oxidation rates of apple chips were decreased with the pre-drying treatment. The sensory analyzes showed that the samples fried by vacuum-combined infrared radiation had the highest scores in all sensory characteristics than deep-fat fried samples. Pre-dried apple samples (41% moisture) fried at 350W infrared power under 400 mmHg vacuum pressure had the highest score for general acceptance. The results showed that VCIR would be an alternative frying method for producing healthier apple chips with less oil content and higher quality.

The Influence of the Proportion of Bones and Meat Catfish (Clarias batrachus) and Frying Time on the Quality of Catfish Floss

Catfish is a freshwater fish that is often found but has not been used optimally. One alternative use of catfish is processed into catfish floss. This research aims to determine the effect and best treatment of the proportion of bones and meat of catfish with frying time. This research used a completely randomized design (CRD) factorial with 2 factors and 2 replications. Factor I is the proportion of bone: meat of catfish (30:70, 50:50, 70:30). Factor II is the frying time (60 minutes, 90 minutes, 120 minutes). Observation data were analyzed using ANOVA with a level of 5%. If there were significant differences between treatments, the DMRT test was continued. The best treatment in this study was a long frying treatment of 60 minutes with the proportion of bone: catfish meat (30:70) producing shredded catfish with calcium levels (6.78%), water content (8.81%), ash content (7.04%), fat content (27.02%), TBA number (0.18mg.MDA/kg), color scoring test 1.28 (yellow) and aroma scoring test 4.48 (slightly burnt).

Optimization of frying time and temperature for the development of quality chips from varieties of sweet potato (Ipomoea batatas L.Lam)

Consumers seek low-fat fried products with appealing color, texture, and taste to avoid health issues like obesity and cardiovascular disease associated with high-oil-content foods. Frying conditions, including time and temperature, greatly affect the moisture, texture, oil content, and color of fried foods. The objective of this study was to optimize frying time and temperature to obtain quality fried chips from three varieties of orangefleshed sweet potato roots. The study examined how frying temperature (ranging from 140 to 180°C) and time (2 to 6 mins) affect the quality of fried chips, assessing attributes like moisture content, oil content, color, and texture. Significant impacts of frying time and temperature on chip quality were found across all varieties using central composite design tests and mathematical models (p&lt;0.05). Optimal frying conditions were determined through response surface methodology analysis, which was 154.8℃ for 3.82 mins, 160.1℃ for 3.66 mins, and 162.65℃ for 3.04 mins for Kabode, Dilla, and Kulfo varieties, respectively, guiding sweet potato fried chip producers to achieve satisfactory results economically and efficiently.

Multifractal characterization of fried foods pore microstructure

This study aimed to unravel the multifractal properties of internal microstructure in relation to textural evolution of meat-analog (MA) based coated fried foods. Wheat and rice flour-based batters were used to coat MA model that was deep fried at 180 °C for 2, 4 and 6 min in canola oil. Internal pore microstructures were investigated by X-ray microtomography based multifractal analysis (MFA) and texture were assessed by mechanical texture analyzer. Results showed that batter coatings greatly influenced the formation of internal microstructure during frying as well as post-frying mass redistribution and textural evolution. The frying time impacted the evolution of micropores, and porosity showed a positive correlation with the fat content of MA-based fried products. Porous, low-moisture and high-fat containing coated fried MA-based product demonstrated higher textural stability. Internal microstructure (pore distribution) of fried MAs were heterogenous and possessed multifractal scaling behavior, as depicted by MFA outcomes (Singularity & Rényi spectra). Strong correlation observed between moisture-fat, texture, porosity and selected multifractal parameters (Δα, Δfα, R-L, D1, D2, ΔD).

Pulsed electric field effect on acrylamide reduction and quality attributes of continuous-style Lamoka potato chips

Potato chips are a popular snack, well-liked because of their texture-flavor combination. Potato chips are made by frying slices of potato in vegetable oil to achieve a crispy texture. Frying potato slices initiates the Maillard reaction, resulting in chemical changes that enhance taste, color, and texture, but also undesired acrylamides, which are suspected carcinogens. The application of pulsed electric field (PEF) technology is commonly used in French fry processing operations to prolong cutting blade sharpness and reduce waste, energy consumption, and water usage. Despite these attributes, PEF systems have not yet gained widespread adoption by potato chip producers. In the current study, Lamoka potatoes were PEF-treated prior to continuous frying into potato chips. The effect of specific energy at 0.75 kJ/kg (Low-PEF) and 1.5 kJ/kg (High-PEF) and electric field strength of 1 kV/cm, frequency of 24 kV, and pulse width of 6 μs versus untreated (control) samples was studied, then batches of 250 g of slices were fried at 170 °C or 185 °C for two frying times to obtain potato chips with acrylamide levels below the California Proposition 65 limit (275 ng/g). The Lamoka potato chip product quality metrics that were assessed include moisture, fat, reducing sugars, asparagine, acrylamide, chip color, and texture. PEF treatment of Lamoka potatoes resulted in chips fried in 10 % less time, lower oil content by 8 %, and a decrease of reducing sugars by 19.2 %, asparagine by 42.0 %, and acrylamide by 28.9 %. The PEF fried chips were lighter in color but maintained textural attributes compared to continuous frying cooking. The process of frying potato slices at 170 °C for 150 s with High-PEF yielded potato chips with acrylamide content below the California Proposition 65 limit; which speaks to the health implications for consumers and the quality and safety of these chips.

Effect of different starches in batter formulation on oil content and associated quality attributes of fried chicken nuggets

Persistent consumption of heavily fried and breaded foods over an extended period may have the potential to contribute to the development of cardiovascular, cerebrovascular diseases, and elevated blood pressure. The potential of coating using native starches (cassava, sweet potato, and corn) in batter formulation to reduce oil uptake as well as their effects on other quality attributes (moisture, colour and textural properties) were investigated. The chicken nuggets coated with batter from different starches were fried at 170 °C for 5 to 25 min. Scanning electron microscopy (SEM) was used to study changes in microstructural properties of fried chicken nuggets samples at different time intervals. The chicken nuggets coated with batter from sweet potato starch had lower oil (13.09%) and moisture (30.49%) contents compared with those coated with other starches. The SEM revealed that longer frying duration produced chicken nuggets with fewer gas cells and pores and subsequently lower oil content. There are changes in the colour and textural properties of the fried chicken nuggets irrespective of the starches used in batter formulation. Application of starches in batter formulation at different frying time affected some quality attributes of fried chicken nuggets with sweet potato starch having better attributes when compared with others.Graphical

Characterization of physical attributes of cassava chips in different frying conditions

Krepek tette is a variety of casava-based chips. However, the process production is quite different with cassava chips. After peeling, cassava is steamed, flattened, and dried. As one of the culinary signatures of Pamekasan, good quality keripek tette must be guaranteed by the Industry. Crispeness is the most essential factor in assessing the quality of this product. Therefore, this study aims to characterize product quality attributes such as moisture content, thickness expansion, porosity, and color products in different temperatures and frying times. The frying process used the deep frying method. The experiment was designed using two factors, and each experiment used three levels: temperature (150, 160, 170°C) and frying time (40, 50, 60 s). The result showed a higher temperature and frying time, and the moisture content of the product was lower. The thickness expansion increases in line with the temperature rising. However, it decreases with longer frying time. In addition, porosity increases linearly with temperature and frying time. The appearance of the product slightly changes. Before frying, the color of the product is yellowish, and after that, it turns slightly brownish. The result is the potential to develop an evaluation of crispiness quantitatively.

Optimising Technological Treatments with the Taguchi Approach to Reduce Acrylamide and Improve Colour Properties in Potato Chips

Today, consumer demand for food safety, especially in fried foods, is increasing. In the first place, it is demanded to reduce the amount of food toxins, in particular toxins resulting from the thermal process such as acrylamide. This study aimed to examine the effect of different technological treatments on the optimisation of minimum acrylamide and maximum colour properties by applying the Taguchi approach in the production of chips. In this study, design of experiments, signal-to-noise (S/N) ratio, analysis of variance, and regression analysis methods were used to optimise the minimum acrylamide and redness (a*), maximum brightness (L*), and yellowness (b*) values. The optimal parameters for acrylamide were found to be 90 °C slice washing temperature, 175 °C frying temperature, and 175 s frying time. The optimal parameters for colour analysis were determined as 30 °C slice washing temperature, 175 °C frying temperature, and 175 s frying time. Analysis of variance showed that frying temperature and time had a significant (p < 0.05) effect on the results. It was determined that a decrease in frying temperature and time led to a decrease in the amount of acrylamide and redness and an increase in brightness and yellowness. According to the results of the analysis of variance, the most effective technological treatments were frying temperature with effect rates of 37.45% and 60.26% for acrylamide and L* values, respectively, and frying time with effect rates of 40.50% and 44.19% for a* and b* values, respectively. As a result of the study, through the Taguchi method, while quality features in chips were preserved, the amount of acrylamide was reduced.

Pengaruh Suhu dan Dimensi Potongan pada Pembuatan Keripik Nanas Menggunakan Penggorengan Vakum (Vacuum Frying)

Pineapple is a fruit that is generally consumed fresh by Indonesian people. The potential for pineapple fruit in Indonesia is quite good, but its utilization and marketing have not been fully implemented. Apart from that, pineapples are easily damaged so proper post-harvest handling is needed to maintain their shelf life, one of which is processing them into chips. The technology that can be used in making chips is a vacuum frying machine to maintain the appearance of color, taste, aroma and crispness in the chips produced. The research aims to determine the effect of temperature and variations in the dimensions of fruit pieces on making pineapple chips using vacuum frying. The temperature used in this research consisted of three levels including temperatures of 75, 80, and 85 ℃ and three levels of cut dimensions including dimension 1 (circle), cut dimension 2 (half circle), and cut dimension 3 (quarter circle). After conducting research and data analysis, it was found that the effect of treatment interactions on the yield value and frying time was obtained. The cut dimension factor has a significant effect on the color and crispness of pineapple chips using vacuum frying. Keywords: Cut Dimensions, Pineapple, Temperature, Vacuum Frying

Understanding changes in moisture state, wheat gluten structure and oil penetration of breaded fish nuggets during frying

To understand the changes in moisture state, wheat gluten (WG) structure and oil penetration during deep-fat frying, batter-breaded fish nuggets (BBFNs) were prepared using the batter with a wheat starch and WG blend at a ratio of 11:1 (w/w), then fried at different temperatures (150–190 °C) and times (30–150 s). As the increase of frying temperature and the prolongation of frying time, a significant portion of bound water in the BBFNs converted to the free water, the fluorescence intensity decreased significantly and the secondary structure of WG changed from disorder to order, while the opposite trend was presented for the 190 °C and 150 s, respectively. The increase of frying temperature significantly reduced the surface hydrophobicity. In addition, the pores and cracks in the crust gradually grew larger, causing the surface oil content of fried BBFNs decreased first and then increased, accompanying with an increased content of penetrated oil and the expanded Sudan Red B dyeing area. This study indicated that frying temperature and frying time significantly changed the moisture state and WG structure in the crust, thereby affecting the oil penetration. The results could be used to provide a scientific guidance for the large-scale production of low-fat fried BBFNs.