Effect of microwave heating and vacuum oven drying of potato strips on oil uptake during deep-fat frying

Reduction of oil absorption and acrylamide content in banana slices by infrared frying

BACKGROUND

The crust characteristics of fried crisps determine their oil absorption. Starch structures, as the main components of fried starchy fruits and vegetables, influence their crust formation and properties. This study investigated the reduction of oil uptake and acrylamide content in infrared-fried (IF) banana slices by modifying starch structures at varying infrared power levels.

RESULTS

Infrared heating improved heat transfer and surface moisture removal in fried banana slices. It facilitated crust formation in the IF samples and produced increased crust uniformity, crust ratio, and hardness. Analysis of the porous properties showed that the volume fraction of pores sized 100-250 μm was reduced in IF samples but the proportion of pores with a diameter ranging from 0.02 to 10 μm was increased. Infrared frying reduced the total oil uptake, surface oil, and structural oil content in banana slices, and each of these measures decreased as infrared power levels increased. Characterization of the starch structures suggested that the damage to the crystalline structure was increased in IF samples and more starch-lipid complexes were generated, which would be responsible for the formation of a denser and thicker crust. The acrylamide content in the IF sample was reduced, as determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS).

CONCLUSION

Modifications to starch structures (crystalline structures and chemical structures) play a crucial role in oil absorption in fried starchy fruits and vegetables. Infrared frying can be used as an alternative method to produce low-fat fruits and vegetable crisps with reduced acrylamide content. © 2024 Society of Chemical Industry.

Exploring oil absorption and distribution in immersion-fried pantoa (Indian dairy dessert): effects of frying media

The kinetics, oil migration pattern and the role of frying media during immersion frying of 'pantoa', a dairy dessert, at the microstructural level were studied using confocal laser scanning microscopy (CLSM). After 6 min of frying, the depth of oil migration in pantoa increased from 0 to 3.16 mm in clarified butter (locally called 'ghee') and 3.81 mm in sunflower oil. Migration was 1.6 times higher and 1.25 times deeper in pantoa fried in sunflower oil than in clarified butter because of higher moisture loss and pore development. The near absence of fluorescence in the CLSM images of pantoa core evidenced that oil did not penetrate the core. Moisture loss and oil migration (fat uptake) were strongly correlated (r = 0.99). CLSM and optical scan images established that oil migrated into pantoa only at the end of frying. Thus, frying of pantoa in clarified butter would be better in terms of minimizing fat migration. The extent and depth of oil migration in the crust and core of pantoa in sunflower oil and clarified butter have been mapped, quantified and compared. This study helps to instantiate the oil/fat migration process in complex and dense fried foods. Also, it will be relevant for the food industry in terms of optimizing the fat content of fried products, thereby avoiding excess oil and produce healthy foods of desired quality.

Effects of ball milling treated wheat flour and maltodextrin on the texture and oil absorption properties of fried batter-coated cashews and almonds

In this study, the effects of wheat flour treated with ball milling (BM) and maltodextrin on the oil absorption and textural characteristics of fried batter-coated cashews and almonds (BCAs) were investigated. The result showed that the crystallinity of the starch granules in wheat flour decreased after the BM treatment. Furthermore, the ΔH of the batter decreased as the BM time was elongated, but the addition of maltodextrin had no significant impact on ΔH. Both BM-treated wheat flour and maltodextrin increased the fracturability and decreased the oil content of the fried BCAs' batter. The addition of BM-treated wheat flour and maltodextrin decreased the oil content of the batter from 28.93% to 18.75% for batter-coated cashews and from 30.92% to 18.61% for batter-coated almonds. Overall, the addition of BM-treated wheat flour and maltodextrin in batter is an effective approach to decrease oil content and improve the textural quality of fried BCAs.

Review of formation mechanisms and quality regulation of chewiness in staple foods: Rice, noodles, potatoes and bread

Staple foods serve as vital nutrient sources for the human body, and chewiness is an essential aspect of food texture. Age, specific preferences, and diminished eating functions have broadened the chewiness requirements for staple foods. Therefore, comprehending the formation mechanism of chewiness in staple foods and exploring approaches to modulate it becomes imperative. This article reviewed the formation mechanisms and quality control methods for chewiness in several of the most common staple foods (rice, noodles, potatoes and bread). It initially summarized the chewiness formation mechanisms under three distinct thermal processing methods: water medium, oil medium, and air medium processing. Subsequently, proposed some effective approaches for regulating chewiness based on mechanistic changes. Optimizing raw material composition, controlling processing conditions, and adopting innovative processing techniques can be utilized. Nonetheless, the precise adjustment of staple foods' chewiness remains a challenge due to their diversity and technical study limitations. Hence, further in-depth exploration of chewiness across different staple foods is warranted.

Effect of pre-drying and post-frying holding treatments on the oil absorption and quality of fried batter-coated peanuts

In this study, the effect of pre-drying and post-frying holding treatments on the oil absorption and the quality of the fried batter-coated peanuts were explored. The results showed that hot air drying and microwave drying induced the gelatinization of starch in the batter before frying. The thermodynamic properties of starch in the batter after frying indicated that pre-drying could protect the orderliness of the starch. CLSM images showed that the pre-drying treatment reduced the number of large oil spots on the surface of batter of fried batter-coated peanuts. SEM observation revealed that the structure of the batter treated with pre-drying was denser and the number of large pores was reduced after frying. The post-frying holding treatment improved the color and texture of the batter-coated peanuts. In conclusion, the pre-drying and post-frying holding treatment can reduce the oil content and improve the fracturability of the fried batter-coated peanuts.

Recent Trends in the Pre-Drying, Drying, and Post-Drying Processes for Cassava Tuber: A Review

Cassava tuber is an essential staple crop in tropical regions with versatile applications in the food, feed, and industrial sectors. However, its high moisture content and perishable nature necessitate efficient preservation methods to extend its shelf life and enhance its value. Pre-drying, drying, and post-drying processes play pivotal roles in maintaining the quality and usability of cassava products. This review comprehensively examines the current status and future directions in the pre-drying, drying, and post-drying processes of cassava tuber. Various pre-drying or pretreatment methods and drying techniques are evaluated for their impacts on drying kinetics and product quality. Additionally, challenges and limitations in achieving high-quality processing of cassava flour are identified. Future directions in cassava drying methods emphasize the integration of combined pre-drying and drying techniques to optimize resource utilization and processing efficiency. Furthermore, the adoption of advanced online measurement and control technologies in drying equipment is highlighted for real-time monitoring and optimization of drying parameters. The importance of optimizing existing processes to establish a comprehensive cassava industrial chain and foster the development of the cassava deep-processing industry is emphasized. This review provides valuable insights into the current trends and future prospects in cassava drying technologies, aiming to facilitate sustainable and efficient utilization of cassava resources for various applications.

Effect of dry heat and its combination with vacuum heat on physicochemical, rheological and release characteristics of Alocasia macrorrhizos retrograded starches

Retrograded starches have received increasing attention due to their potential excipient properties in pharmaceutical formulations. However, to evade its application-oriented challenges, modification of retrograded starch is required. The study emphasizes influence of dry heating and the dual heat treatment by dry heating amalgamation with the vacuum heat treatment on quality parameters of retrograded starch. The starch was isolated by using two different extraction media (0.05 % w/v NaOH and 0.03 % citric acid) from Alocasia macrorrhizos and then retrograded separately. Further, retrograded starches were first modified by dry heating and afterwards modified with combination of dry and vacuum heating. Modification decreased moisture, ash content and increased solubility. Modified Samples from NaOH media had higher water holding capacity and amylose content. X-ray diffraction revealed type A and B crystals with increasing crystallinity of retrograded heat-modified samples from NaOH media. Thermogravimetric analysis, differential scanning calorimetry confirmed thermal stability. Shear tests showed shear-thinning behavior whereas dominant storage modulus (G/) over loss modulus (G//), depicting gel-like behavior. Storage, loss, and complex viscosity initially increased, then decreased with temperature. In-vitro release reflects, modified retrograded starches offers versatile drug release profiles, from controlled to rapid. Tailoring starch properties enables precise drug delivery, enhancing pharmaceutical formulation flexibility and efficacy.

Intelligence detection of oil absorption in French fries by surface profiles

Surface profiles are important evaluation indices for oil absorption behavior of fried foods. This research established two intelligent models of partial least-squares regression (PLSR) and back propagation artificial neural network (BP-ANN) for monitoring the oil absorption behavior of French fries based on the surface characteristics. Surface morphology and texture of French fries by rapeseed oil (RO) and high-oleic peanut oil (HOPO) at different temperatures were investigated. Results showed that oil content of samples increased with frying temperature, accounting for 37.7% and 41.4% of samples fried by RO and HOPO respectively. The increase of crust ratio, roughness and texture parameters (Fm, Nwr, fwr, Wc) and the decrease of uniformity were observed with the frying temperature. Coefficients of prediction set of PLSR and BP-ANN models were more than 0.93, which indicated that surface features combined with chemometrics were rapid and precise methods for determining the oil content of French fries.

3D Printing of smart labels with curcumin-loaded soy protein isolate

A two-step method for preparing smart labels that can monitor food freshness through color change is presented. The conventional casting method for such labels is not cost-effective, as it uses organic solvents and requires additional cutting processes. Our method is more eco-friendly and customizable, as it uses water as the sole solvent and 3D printing as the fabrication technique. First, curcumin was encapsulated with soy protein isolate (SPI) by a pH-driven method involving hydrogen bonding and hydrophobic interactions. Subsequently, the SPI-curcumin complex was blended with gelatin to create a printable ink. The ink has suitable rheological properties for extrusion, with a yield stress of 400-600 Pa and a viscosity of 122.93-142.82 Pa·s at the optimal printing temperature. The complex modulus of the ink increases to above 2 × 103 Pa when cooled to 25 °C, indicating rapid gel formation. The application of these smart labels to minced meat demonstrated their ability to reflect its freshness by transitioning from yellow to red. Furthermore, the printability and mechanical properties of the labels can be adjusted by changing the glycerol/water ratio. This innovative approach is a promising solution for producing environmentally friendly and customizable smart labels for food freshness monitoring.

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.

Comparative study of conventional frying and air frying on the quality of potatoes (Solanum tuberosum L.)

The human being has historically consumed fried foods for centuries; however, conventional frying has a disadvantage, immersion in vegetable and/or animal oils, which leads to the search for different options. This is why air frying is a good alternative, which still has a wide field of study. In this work, frozen French fries of a brand marketed in Mexico that were subjected to frying in canola oil and air frying were compared. They were evaluated through the change in the removed moisture content, water activity, color profile, hardness, fracturability, and surface damage by SEM, thermal analysis by MDSC, and chemical by FTIR-ATR spectroscopy. Air-fried French fries were found to contain about 48% less moisture, fewer perceptible color changes, and less surface damage translated into better crunchiness compared with conventionally fried. It was also found that the changes at the chemical level are smaller, mainly attributed to the absence of canola oil and that the thermal transitions are more stable in terms of temperatures and enthalpies, which makes it possible to emphasize that air frying is a good alternative for developing new fried products that allow expanding the variety of these in the market without sacrificing some quality attributes.

Effect of moderate electric field voltage on the quality and heat transfer characteristics of potato strips during deep-frying process

The application of moderate electric field (MEF) on frying can influence the quality of fried products; however, the associated mechanism is unknown. This study investigated the effects of MEF voltage on the quality and surface heat transfer of potato strips fried with an MEF. With increasing MEF voltage, the moisture content, hardness, starch gelatinization rate, and shrinkage of the potato strips significantly increased (p < 0.05), while their oil content and brightness decreased (p < 0.05). The decrease in their oil content and brightness indicated improved crust formation, which reduced oil absorption. The potato strips fried under higher voltages exhibited lower oil contents and better microstructure than those fried under lower voltages. A possible mechanism comprised MEF increasing the heat transfer coefficient (h) between oil and potato strips, thereby accelerating crust formation; moreover, h values increased with MEF voltage. The results indicate the potential application of MEF in food frying.

Impact of different microwave treatments on food texture

Electromagnetic waves are frequently used for food processing with commercial or domestic type microwave ovens at present. Microwaves cause molecular movement by the migration of ionic particles or rotation of dipolar particles. Considering the potential applications of microwave technique in food industry, it is seen that microwaves have many advantages such as saving time, better final product quality (more taste, color, and nutritional value), and rapid heat generation. Although microwave treatment used for food processing with developing technologies have a positive effect in terms of time, energy, or nutrient value, it is also very important to what extent they affect the textural properties of the food that they apply to. For this purpose, in this study, it has been investigated that the effects of commonly used microwave treatments such as drying, heating, baking, cooking, thawing, toasting, blanching, frying, and sterilization on the textural properties of food. In addition, this study has also covered the challenges of microwave treatments and future work. In conclusion, microwave treatments cause energy saving due to a short processing time. Therefore, it can be said that it affects the textural properties positively. However, it is important that the microwave processing conditions used are chosen appropriately for each food material.

Radio frequency as an innovative method to produce low-fat French fries

BACKGROUND

A large amount of evidence shows that excessive fat intake can increase the risk of obesity, type 2 diabetes, non-alcoholic fatty liver disease, and cardiovascular disease. The main purpose of this study was to use radio frequency (RF) technology to prepare low-fat French fries.

RESULTS

RF treatment for 10 min significantly decreased the force required to cut potatoes and inhibited the enzymatic browning of fresh-cut potatoes. Moreover, RF treatment increased the hardness, gumminess, and chewiness of French fries from 388.55 g, 85.67, and 33.27 to 776.93 g, 159.36, and 70.11, respectively. Furthermore, RF treatment for 10 min reduced the oil content of French fries by 28.0% compared to that of the control group. This result was related to the pre-gelatinized potato starch content after RF treatment. Pre-gelatinized starch forms a 'protective film', that prevents oil from entering the fries during frying.

CONCLUSION

Moderate RF treatment (10 min) reduced the oil content of French fries without making their texture significantly different from that of commercial French fries. These findings may provide a new perspective for the application of RF technology in the development of low-fat fried foods. © 2022 Society of Chemical Industry.

Inhibitory effect of chitosan coating on oil absorption in French fries based on starch structure and morphology stability

The effect of chitosan (CS) coating on oil absorption, water migration, starch structure and morphology in French fries was evaluated. The penetrated surface oil, structure oil, total oil content, and a* of coated fries decreased, while the water content, L*, b*, and hardness significantly (P < 0.05) increased compared to uncoated samples. 1 % CS-coated fries had the lowest oil content, which decreased by 43.0 % compared to uncoated samples. CS-coated fries had higher free water, and lower T₂ relaxation time, immobile and binding water than the control. CS coating reduced the pores on the fries' surface and the interaction between oil and the component of fries, which was observed by confocal laser scanning microscopy and scanning electron microscopy (SEM). As for starch morphology, the pores and cracks of starch granules in the coated samples reduced. As for the starch structure, the relative crystallinity, R_1047/1022 respectively increased by 47.2 % and 2.35 times, and ΔH of CS-coated fries increased from 0 to 2.09 J/g, indicating that the long-range crystalline structure, short-range ordered structure, and hydrogen bonds between the double helices in starch increased. Therefore, CS coating reduced oil penetration into fries by reducing water migration and increasing starch ordered structure and morphological integrity.

Pengaruh Tepung Beras Pragelatinisasi terhadap Penyerapan Minyak dan Sensori Kue Cucur

Cucur is a traditional food with oily appearance,which may affect the sensory acceptance. Thus, in this research we attempted to reduce its oil absorption by using pregelatinized rice flour as the ingredient for cucur dough. The type of rice and temperature of extrusion process affect the characteristics of pregelatinized rice flour and final products. Thus, the objective of this research was to determine the effect of using pregelatinized rice flour on the oil uptake and sensory of cucur. The type of rice used were IR64 and IR42, and the extrusion process temperatures were 130 and 150°C. The oil uptake by cucur made with pregelatinized rice flour was analyzed during deep frying and sensory analysis was done on the resulting cucur. The results showed that the type of rice, temperature of extrusion, and their interactions had a significant effect on the characteristics and sensory of cucur. A combination of IR42 and 150°C resulted in cucur with 35.97% moisture content, 19.32% fat content, 18.14% moisture loss, 18.14% oil uptake, while the overall sensory attribute was acceptable to the panelists. Use of pregelatinized rice flour resulted in decrease in the oil uptake and moisture loss. Cucur made with pregelatinized rice flour has desirable intensities of sensory attributes (appearance, flavor, texture, and mouthfeel), which result in the higher overall preferences score.

Effect of oil surface activity on oil absorption behavior of potato strips during frying process

Oil absorption behavior of fried foods is affected by oil property during frying process. The present study investigated the effect of oil viscosity and surface activity on the oil uptake of fried potato strips with frying temperature. Results showed that oil content of palm oil (PO) and soybean oil (SBO) in fried strips increased with the frying temperature between 140 °C and 180 °C, while deceased at 200 °C. Oil distribution determined by LF-NMR and CLSM confirmed the changes of oil content of fried potato strips. Interfacial tension and surfactant content (monoglycerides, diglycerides, total polar compounds) of PO and SBO increased with frying temperature and affected the oil absorption of fried strips. Frying temperature and oil type showed no effect on surface tension. Besides, the higher level of viscosity, interfacial tension and surfactants of SBO than those of PO facilitated the more SO and TO of fried potato strips.

Relationship between crust characteristics and oil uptake of potato strips with hot-air pre-drying during frying process

Crust property is an important factor in affecting the oil absorption of potato strips. The present study aimed at illustrating detailed crust characteristics in relation to oil uptake of potato strips during frying as a function of hot-air pre-drying time. Results showed that oil content decreased with the increasing hot-air pre-drying time. Oil distribution determined by LF-NMR and CLSM confirmed pre-drying could reduce oil uptake of potato strips. Structural and textural analysis of crust revealed the increase in crust ratio, roughness and texture (Fm, Nwr, fwr, Wc), and decrease in crust uniformity. Results of microscopic structure unraveled that the crust of fried strips after pre-drying for 180 min became thick and compact with almost no pores. Our results suggested that hot-air pre-drying caused the formation of harder and denser crust, and oil uptake of fried potato strips after pre-drying largely depended on crust texture rather than morphology.