Effect of Pretreatments and Air-Frying, a Novel Technology, on Acrylamide Generation in Fried Potatoes

Acrylamide formation in air-fried versus deep and oven-fried potatoes

Introduction

Present study investigates the effects of different home pre-treatment processes and cooking techniques on the acrylamide content of fried potatoes.

Methods

Potato sticks were prepared in two different pre-treatment ways (washing and soaking) and cooked with three other techniques (air frying, deep frying, and oven frying). Acrylamide analyses were performed on cooked potatoes using an LC-MS/MS method.

Results

The highest acrylamide content was found in potatoes cooked using the air fryer (12.19 ± 7.03 μg/kg). This was followed by deep frying (8.94 ± 9.21 μg/kg) and oven frying (7.43 ± 3.75 μg/kg). However, the difference between the acrylamide contents of the potatoes according to the cooking methods was not statistically significant. The acrylamide content of the potatoes that were subjected to soaking in all three ways was lower than the potatoes that were not soaked and only washed. In the deep-frying method, it was found statistically significant that the soaked potatoes contained less acrylamide (p = 0.029).

Discussion

It is important to highlight the relatively low acrylamide levels found in oven-frying, lower than air frying in both washing and soaking groups in the present study. Although air fryers, which have become widely used as an alternative to deep frying in recent years, provide French fries with less oil, their role in the formation of acrylamide should be further investigated.

Toxicity, metabolism, and mitigation strategies of acrylamide: a comprehensive review

Acrylamide, a food-borne chemical toxicant, has raised global concern in recent decades. It mainly originated from reducing sugar and free amino acid interactions in the carbohydrate-rich foodstuffs heated at high temperatures. Due to the neurotoxicity and carcinogenicity of AA, the mechanism of formation, toxic effects on health, and mitigation strategies, including conventional approaches and innovative technologies, have been of great interest since its discovery in food. Potato products (especially French fries and crisps), coffee, and cereals(bread and biscuit) are renowned contributors to AA's daily intake. The best preventive methods discussed in the literature include time/temperature optimization, blanching, enzymatic treatment, yeast treatment, additives, pulsed electric fields, ultrasound, vacuum roasting, air frying, and irradiation, exhibiting a high efficacy in AA elimination in food products.

A review on the frying process: Methods, models and their mechanism and application in the food industry

Frying is one of the most popular and traditional processes used in the food industry and food services to manufacture products that are high in quality and with unique sensory characteristics. The most common method of frying is deep-fat frying, used worldwide due to its distinct flavor profile and sensory aspects, which leads to physio-chemical changes at both macro and micro levels. One of the major concerns with deep-fried foods is their high oil content, and a variety of metabolic disorders can be caused by overconsumption of these foods, including heart disease, obesity, and high cholesterol. Due to their enticing organoleptic properties with their delicious flavor, pleasing mouthfeel, and unique taste, making them irresistible, it is also responsible for undesirable and unacceptable characteristics for consumers. Oil absorption can be reduced by developing novel frying methods that limit the amount of oil in products, producing products with fewer calories and oil while maintaining similar quality, flavor, and edibility. In addition, different pretreatments and post-frying treatments are applied to achieve a synergistic effect. The transfer of mass and heat occurs simultaneously during frying, which helps to understand the mechanism of oil absorption in fried food. Researchers have discovered that prolonged heating of oils results in polar compounds such as polymers, dimers, free fatty acids, and acrylamide, which can alter metabolism and cause cancer. To reduce the oil content in fried food, innovative frying methods have been developed without compromising its quality which also has improved their effect on human health, product quality, and energy efficiency. The aim is to replace the conventional frying process with novel frying methods that offer fried food-like properties, higher nutritional value, and ease of use by replacing the conventional frying process. In the future, it might be possible to optimize frying technologies to substantially reduce fried foods' oil content. This review focuses on a detailed understanding of different frying techniques and attempts to focus on innovative frying techniques such as vacuum frying, microwave cooking, and hot-air frying that have shown a better potential to be used as an alternative to traditional frying.

Impact of Air-Drying Temperature on Antioxidant Properties and ACE-Inhibiting Activity of Fungal Fermented Lentil Flour

Solid-state fermentation (SSF) with Pleurotus ostreatus enhances the nutritional value of legumes. However, drying can cause significant changes in physical and nutritional properties of the final products. Thus, this work studies the impact of air-drying temperature (50, 60, and 70 °C) on relevant properties (antioxidant properties, ACE-inhibitory capacity, phytic acid, colour, and particle size) of two fermented lentils flour (Pardina and Castellana) using freeze-drying as a reference method. Castellana variety is a better substrate for Pleurotus, generating four times more biomass. In addition, an almost total reduction of phytic acid from 7.3 to 0.9 mg/g db is achieved in this variety. Air-drying significantly decreased the particle size and the final colour with ΔE > 20; nonetheless, the temperature does not play a crucial role. SSF decreased the total phenolic content and the antioxidant capacity regardless of the variety, however, drying at 70 °C increased total phenolic content (186%) in fermented Castellana flour. Comparing drying methods, freeze-drying implied a higher decrease in those parameters, reducing the TPC from 2.4 to 1.6 and from 7.7 to 3.4 mg gallic acid/g db in Pardina and Castellana dried flours. Finally, the flours inhibit the angiotensin I-converting-enzyme, and fermentation and drying increased their potential cardiovascular benefits.

Study on the physicochemical and flavor characteristics of air frying and deep frying shrimp (crayfish) meat

This study aimed to compare the changes in the quality characteristics of air-fried (AF) shrimp meat and deep-fried (DF) shrimp meat at different frying temperatures (160, 170, 180, 190°C). Results showed that compared with DF, the moisture and fat content of air-fried shrimp meat (AFSM) was lower, while the protein content was higher. At the same frying temperature, the fat content of the AFSM was 4.26-6.58 g/100 g lower than that of the deep-fried shrimp meat (DFSM). The smell of the AFSM and DFSM was significantly different from that of the control group. The results of the electronic tongue showed that each of the two frying methods had its flavor profile. Gas chromatography-ion mobility spectrometry (GC-IMS) identified 48 compounds, and the content of volatile compounds detected in AFSM was lower than that in DFSM. Among them, the highest level of volatile compound content was found in the DF-190. E-2-pentenal, 2-heptenal (E), and methyl 2-methyl butanoate were identified only in DFSM. In addition, a total of 16 free amino acids (FAAs) were detected in shrimp meat. As judged by sensory evaluation, the AFSM at 170°C was the most popular among consumers.

Effects of sucrose and sodium chloride pretreatments on cassava and plantain chips fried in CLA-enriched soybean oil: an analysis of acrylamide content, microstructure, and other physical properties

The purpose of this research was to evaluate the effect of soaking plantain and cassava chips in sucrose or sodium chloride (NaCl) on their physical properties and acrylamide content after frying in Conjugated Linoleic Acid (CLA)-enriched soybean oil. Plantain and cassava were cut into 1 mm thick slices and soaked for 20 min in a solution of 30% sucrose or 3% NaCl at 40 °C, separately. Soaking in sucrose and NaCl had no significant effect (p < 0.05) on water loss, porosity, hardness, or microstructure. The acrylamide content ranged from 634 to 3177 µg/kg. The use of CLA-enriched oil had no significant effect (p < 0.05) on the physical characteristics evaluated in this study. Frying reduced the CLA content in the chips from an initial 31.8% in the oil to 22.25 and 21.69% in plantain and cassava chips, respectively.

Formation of advanced glycation end products by novel food processing technologies: A review

Advanced glycation end products (AGEs) are a diverse group of compounds formed endogenously and exogenously due to non-enzymatic glycation of proteins and lipids. Although the effects of heating on AGE concentrations in foods are known, few studies have been published addressing the effects of new processing technologies on AGE formation. This work focuses on the current scientific knowledge about the impacts of novel technologies on AGE formation in food products. Most studies do not measure AGE content directly, evaluating only products of the Maillard reaction. Moreover, these studies do not compare distinct operational conditions associated with novel technologies. This lack of information impacts negatively the establishment of process-composition relationships for foods with safe AGE dietary intakes. Overall, the outcomes of this review suggest that the use of novel technologies is a promising alternative to produce food products with a lower AGE content.

Influence of Water, NaCl and Citric Acid Soaking Pre-Treatments on Acrylamide Content in French Fries Prepared in Domestic Conditions

The aim of this study was to investigate the influence of some pre-treatment applications toward acrylamide mitigation in potatoes fried in domestic conditions modeled after those found in Romania, by using a pan and a fryer. Before being fried in a pan, potato strips were treated in one of the following ways: soaked in cold water for 15, 60, and 120 min (a); soaked in hot water at different combinations of temperatures and durations (60, 70, 80 °C for 5, 10, 15 min) (b); soaked in a NaCl solution (c), and; in a citric acid solution (d) both solutions of 0.05% and 1% concentration for 30 min. For potatoes fried in a fryer, the (a) pre-treatment and soaking in water at 80 °C for 5, 10, and 15 min were applied. Untreated samples were used as a control. French fries were analyzed in terms of moisture and acrylamide content, color, and texture parameters. The pre-treatments applied reduced the acrylamide content in French fries by 4–97% when fried in the pan and by 25–47% when fried in the fryer. Acrylamide content of French fries was negatively correlated with L* parameter and moisture content and positively correlated with a* parameter. The pre-treatments applied can be used successfully by consumers to reduce acrylamide content.

Impact of Cultivar Selection and Thermal Processing by Air Drying, Air Frying, and Deep Frying on the Carotenoid Content and Stability and Antioxidant Capacity in Carrots (Daucus carota L.)

Epidemiological data suggest that consuming diets rich in carotenoids can reduce the risk of developing several non-communicable diseases. Thus, we investigated the extent to which carotenoid contents of foods can be increased by the choice of food matrices with naturally high carotenoid contents and thermal processing methods that maintain their stability. For this purpose, carotenoids of 15 carrot (Daucus carota L.) cultivars of different colors were assessed with UHPLC-DAD-ToF-MS. Additionally, the processing effects of air drying, air frying, and deep frying on carotenoid stability were applied. Cultivar selection accounted for up to 12.9-fold differences in total carotenoid content in differently colored carrots and a 2.2-fold difference between orange carrot cultivars. Air frying for 18 and 25 min and deep frying for 10 min led to a significant decrease in total carotenoid contents. TEAC assay of lipophilic extracts showed a correlation between carotenoid content and antioxidant capacity in untreated carrots.

Mitigation effects of high methoxyl pectin on acrylamide formation in the Maillard model system

Acrylamide (AA) is a potential carcinogen formed during the process of food heating. Pectin is natural food additive widely presented in fruits and vegetables. This study aimed at investigating the influence of the addition of high methoxyl apple pectin (esterification degree: 82.6%) on AA inhibition in the asparagine (Asn)/glucose (Glc) model system. Results showed that temperature (120-180 °C), pH value (6.0-7.2), pectin addition (0.2-1.0%, w/v), substrate concentration (0.01-0.5 M) and molar ratio of Asn/Glc (5:1-1:10) had significant influence on inhibition of pectin on AA formation. With adding 1.0% (w/v) pectin, the pH value, Glc consumption and Schiff base abundance declined in Asn/Glc model system. Moreover, heating treatment decreased the pH value, molecular weight, esterification degree and galacturonic acid content of pectin. Finally, the pectin degradation product was identified, which might compete with Glc for Asn in Maillard reaction, led to AA reduction. This study provided distinct evidence for controlling AA formation.

Optimization of the Frying Temperature and Time for Preparation of Healthy Falafel Using Air Frying Technology

Air-frying is an innovative technique for food frying that uses hot air circulation to prepare healthy products. The objectives of this study were to establish simplified models to reflect the efficacy of the air frying process at varying temperatures and times on the quality attributes of falafel, and to optimize the frying conditions for producing air-fried falafel. Moisture content, color, fat content, hardness, and sensory evaluation of the fried falafel were analyzed under varied temperatures (140 °C, 170 °C, and 200 °C) and time periods (5 min, 10 min, and 15 min). Statistical analysis was then applied to obtain the best fit model that can describe the properties of fried falafel. Results indicated that moisture content, fat content, and L*-value of air-fried falafel were adversely related to the frying temperature and time, but the hardness and ΔE of fried falafel were increased as the frying temperature and time increased. Moreover, an increase followed by a decrease was shown for the appearance, aroma, crispness, taste, and overall preference scores with the increase in frying temperature and time. The regression analysis showed that the proposed models could be properly used for predicting the properties of the fried falafel. In addition, the overlaid plots resulted in the optimum frying temperature of 178.8 °C and time of 11.1 min. Interestingly, the fat content of the air-fried falafel reduced by 45% at optimal frying conditions compared with that for the deep-fat fried one at 180 °C for 7 min (control). In comparison, the air-fried falafel was lower in fat content, higher in hardness with more acceptable appearance and crispness scores than deep-fat fried falafel. Such information could be beneficial to the manufacturers of the falafel to produce an optimal and healthy product.

Acrylamide in non-centrifugal sugars and syrups

BACKGROUND

Acrylamide in foods has been widely studied because of its possible carcinogenicity. Most of the foods investigated were prepared using low moisture and high temperature conditions. Non-centrifugal sugars (NCSs), which have been promoted as 'non-chemical' natural sweeteners, contain precursors of acrylamide and their production processes involved prolonged heating. The acrylamide content in 32 commercial NCSs from coconut, cane and palmyra palm purchased in Asian countries was investigated. Additionally, syrups (80 ^o Brix) produced from coconut and palmyra raw saps and cane juice were prepared by evaporation with prolonged heating (2.5 h to reach 100 °C, 1 h to increase to 110 °C, held at 110 °C for 30 min). The compositions and contents of sugars, amino acids and minerals, as well as the physical characteristics of the raw saps, juice and syrups, were determined.

RESULTS

The acrylamide content of these 32 products ranged from < 15 to 4011 μg kg^-1 . The raw saps and juice were mildly acidic (pH 5.14-5.66) and similar values were observed for their syrups (4.73-5.73). The contents of sucrose, fructose and glucose in the saps and juice from these plants were similar, whereas their compositions varied with respect to amino acids. The variation of the ornithine content was significant, demonstrating a striking influence on the extent of acrylamide formation (867-1564 μg kg^-1 ) in the syrups prepared from these materials.

CONCLUSION

The present study emphasizes the importance of a careful monitoring and control of the critical steps invloved in the manufacturing process of NCSs (particularly the evaporation phase), aiming to protect the health and safety of consumers. © 2021 Society of Chemical Industry.

An innovative model for describing oil penetration into the doughnut crust during hot air frying

Hot air frying is one of the newest processing methods that can make healthier fried foods. The mechanism of frying using this method is not understood entirely yet. There is no model available to describe the oil absorption for air-fried foods. In this research, an agent-based model was extended to describe the oil penetration procedure and study the different effects of the cellular structure of crust on oil distribution during hot air frying. Netlogo software was used for the model simulation. The simulation results of oil penetration were in good agreement with experimental data. Obtained results show that the oil penetration procedure divided into three main steps named latent phase, acceleration phase, and deceleration phase. The acceleration phase is the most critical step in doughnut oil absorption. Simulated data also show that oil penetration starts from the thinner parts of the crust. Therefore, it seems that the structure of the crust has an important effect on oil absorption pattern.

Characteristics of French Fries and Potato Chips in Aspect of Acrylamide Content—Methods of Reducing the Toxic Compound Content in Ready Potato Snacks

The reduction of toxic acrylamide content in potato snacks, i.e., French fries and potato chips, is necessary due to the adverse effects of this compound on the human body. Therefore, in the presented review paper, a detailed characterization of French fries and chips in terms of AA content and their organoleptic quality is included. Detailed information was also collected on the raw material and technological factors that affect the formation of acrylamide content, including methods and techniques affecting the reduction of the amount of this compound in potato snacks. The obligation to control the level of acrylamide in various food products (including fried potato snacks with a higher content of this compound), introduced in 2018, has mobilized manufacturers to seek solutions, while scientists conduct further intensive research on the possibility of reducing the level of AA or even eliminating its presence from products. Therefore, it is necessary to conduct such activities, especially, because potato French fries and potato chips are willingly consumed by younger and younger consumers.

Air frying combined with grape seed extract inhibits Nε-carboxymethyllysine and Nε-carboxyethyllysine by controlling oxidation and glycosylation

Advanced glycation end products (AGE), compounds formed in meat at the advanced stage of Maillard reaction, are easily exposed to thermal processing. Improving cooking condition and adding antioxidants are 2 common ways for AGE reduction. The present work compared the inhibition of grape seed extract (GSE) on levels of free and protein-bound N^ε-carboxymethyllysine (CML) and N^ε-carboxyethyllysine (CEL) in chicken breast under deep-frying and air-frying conditions. Efficiency of 5 concentrations of GSE (0.0, 0.2, 0.5, 0.8, and 1.0 g/kg) in retarding oxidation, glyoxal (GO), methylglyoxal (MGO), lysine (Lys), Maillard reaction degree (A₂₉₄, A₄₂₀), and Shiff's base were tested. Results showed that 0.5 g/kg GSE before heating significantly (P < 0.05) reduced AGE in fried breast chicken, whereas excessive supplementation of GSE (0.8 and 1 g/kg) was reverse. Air frying was found significantly (P < 0.05) better than deep frying to reduce the precursor substances (GO, MGO, and Lys) of AGE. In conclusion, GSE-derived polyphenols exhibited different inhibitory effects on oxidation and glycosylation at different concentrations. We found that 0.5 g/kg of GSE combined with air frying was the best recommendation for inhibiting CML and CEL.

Carcinogenic and neurotoxic risks of dietary acrylamide consumed through cereals among the Lebanese population

The present study aims to determine the carcinogenic and neurotoxic risks associated with acrylamide intake from cereal products. Analysis on a UPLC-MS/MS spectrometer revealed that oat-based and mixed cereals contain the highest amount of acrylamide among cereal products with levels as high as 271 and 348 μg/kg, respectively. Children were shown to exhibit both carcinogenic and neurotoxic risks regardless of the type of cereal product consumed. For adults above 50 years of age, only consumers of oat-based cereal products seem to exhibit carcinogenic and neurotoxic risks. To avoid a carcinogenic and neurotoxic risk among the Lebanese population, we propose that food processors set the maximum tolerable concentration for acrylamide in cereal products at 94.8 μg/kg product, a value which is threefolds lower than the average acrylamide levels found in this study. Alternatively, and unreasonably, the average Lebanese population and children among the Lebanese population may choose to cut down on cereal consumption by 1.7- and 7.2-folds respectively, should they want to avoid a health hazard as a result of acrylamide intake. The industry should also respond by optimizing the production process in a way to reduce acrylamide levels in cereals.

Effects of Thawing and Frying Methods on the Formation of Acrylamide and Polycyclic Aromatic Hydrocarbons in Chicken Meat

Air frying is commonly used as a substitute for deep-fat frying. However, few studies have examined the effect of air frying on the formation of potential carcinogens in foodstuffs. This study aimed to investigate the formation of acrylamide and four types of polycyclic aromatic hydrocarbons (PAHs) in air-fried and deep-fat-fried chicken breasts, thighs, and wings thawed using different methods, i.e., by using a microwave or a refrigerator, or by water immersion. The acrylamide and PAHs were analyzed by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) and gas chromatography-mass spectrometry (GC-MS), respectively. Deep-fat-fried chicken meat had higher acrylamide (n.d.-6.19 μg/kg) and total PAH (2.64-3.17 μg/kg) air-fried chicken meat (n.d.-3.49 μg/kg and 1.96-2.71 μg/kg). However, the thawing method did not significantly affect the formation of either acrylamide or PAHs. No significant differences in the acrylamide contents were observed among the chicken meat parts, however, the highest PAH contents were found in chicken wings. Thus, the results demonstrated that air frying could reduce the formation of acrylamide and PAHs in chicken meat in comparison with deep-fat frying.

The Effect of UV-C Stimulation of Potato Tubers and Soaking of Potato Strips in Water on Color and Analyzed Color by CIE L*a*b*

The color of French fries is an organoleptic attribute indicative of this product quality and also a reliable indicator of its safety. The darker the product color, the higher its acrylamide concentration. Acrylamide is an organic compound of the amide group showing neurotoxic and potential mutagenic actions in the human body. The content of acrylamide in fried potato products essentially depends on the contents of reducing sugars in intermediates of French fries’ production. The present study aimed to investigate the effect of UV-C irradiation and the soaking of potato strips in water on French fries’ color. The study was conducted on French fries obtained from tubers of the Innovator variety. The study was performed with the use of a special chamber for UV-C irradiation of biological samples and the CIE L*a*b* model for color analysis. The results of the study demonstrated that UV-C stimulation of potato tubers before processing had a beneficial effect on French fries’ color while the blanching of potato strips and soaking in water at a temperature of 40 °C resulted in the production of French fries lighter in color.

Dietary acrylamide: What happens during digestion

Acrylamide is a well-known potentially carcinogen compound formed during thermal processing as an intermediate of Maillard reactions. Three objectives were addressed: the impact of gastric digestion on acrylamide content of French Fries, chips, chicken nuggets, onions rings, breakfast cereals, biscuits, crackers, instant coffee and coffee substitute; the acrylamide content evolution during gastrointestinal digestion of French fries and chips; and the effectiveness of blanching and air-frying on acrylamide mitigation after gastrointestinal digestion. A significant increase (p-value <0.05) in acrylamide content was observed for most of the products after gastric digestion (maximum registered for sweet biscuits, from 30±8 to 150±48µg/kg). However, at the end of the intestinal stage, acrylamide values were statistically similar (p-value=0.132) for French fries and lower than the initial values (before digestion) in potato chips (p-value=0.027). Finally, the low acrylamide content found in blanched and air-fried samples, remained still lower than for deep fried samples even after gastrointestinal digestion.

Acrylamide: inhibition of formation in processed food and mitigation of toxicity in cells, animals, and humans

Potentially toxic acrylamide is largely derived from the heat-inducing reactions between the amino group of the amino acid asparagine and carbonyl groups of glucose and fructose in plant-derived foods including cereals, coffees, almonds, olives, potatoes, and sweet potatoes. This review surveys and consolidates the following dietary aspects of acrylamide: distribution in food, exposure and consumption by diverse populations, reduction of the content in different food categories, and mitigation of adverse in vivo effects. Methods to reduce acrylamide levels include selecting commercial food with a low acrylamide content, selecting cereal and potato varieties with low levels of asparagine and reducing sugars, selecting processing conditions that minimize acrylamide formation, adding food-compatible compounds and plant extracts to food formulations before processing that inhibit acrylamide formation during processing of cereal products, coffees, teas, olives, almonds, and potato products, and reducing multiorgan toxicity (antifertility, carcinogenicity, neurotoxicity, teratogenicity). The herein described observations and recommendations are of scientific interest for food chemistry, pharmacology, and toxicology, but also have the potential to benefit nutrition, food safety, and human health.