Effects of preliminary treatment by pulsed electric fields and convective air-drying on characteristics of fried potato

Formation of pores and bubbles and their impacts on the quality attributes of processed foods: A review

Pores and bubbles significantly influence the physical attributes (like texture, density, and structural integrity), organoleptic properties, and shelf life of processed foods. Hence, the quality of foods and their acceptance by the consumers could be influenced by the properties and prevalence of pores and bubbles within the food structure. Considering the importance of pores, this review aimed to comprehensively discuss the factors and mechanisms involved in the generation of pores and bubbles during the processing of different food products. Moreover, the characteristics and effects of pores on the properties of chocolates, cheeses, cereal-based foods (like cake, puffed grains, and pasta), dried, and fried products were discussed. The impacts of bubbles on the quality of foam-based products, foam creamers, and beverages were also explored. This review concludes that intrinsic factors (like food compositions, initial moisture content, and porosity) and extrinsic factors (like applied technologies, processing, and storage conditions) affect various properties of the pores and bubbles including their number, size, orientation, and distribution. These factors collectively shape the overall structure and quality of processed food products such as density, texture (hardness, cohesiveness, chewiness), and water holding capacity. The desirability or undesirability of pores and their characteristics depends on the type of products; hence, some practical hints were provided to mitigate their adverse effects or to enhance their formation in foods. For example, pores could increase the nutrient digestion and reduce the shelf life of the products by enhancing the risk of fat oxidation and microbial growth. In conclusion, this study provides a valuable resource for food scientists and industry professionals by discussing the effects of pores on food preservation, heat, and mass transfer (including oxygen, moisture, flavors, and nutrients). Understanding the dynamic changes in porosity during processing will be effective in customization of final product quality with desired attributes, ensuring tailored outcomes for specific applications.

Shelf-Life Enhancement Applying Pulsed Electric Field and High-Pressure Treatments Prior to Osmotic Dehydration of Fresh-Cut Potatoes

From a quality standpoint, it is desirable to preserve the characteristics of fresh-cut potatoes at their peak. However, due to the mechanical tissue damage during the cutting process, potatoes are susceptible to enzymatic browning. This study pertains to the selection of the appropriate osmotic dehydration (OD), high pressure (HP), and pulsed electric fields (PEF) processing conditions leading to effective quality retention of potato cuts. PEF (0.5 kV/cm, 200 pulses) or HP (400 MPa, 1 min) treatments prior to OD (35 °C, 120 min) were found to promote the retention of the overall quality (texture and color) of the samples. The incorporation of anti-browning agents (ascorbic acid and papain) into the osmotic solution improved the color retention, especially when combined with PEF or HP due to increased solid uptake (during OD) as indicated by DEI index (2.30, 1.93, and 2.10 for OD treated 120 min, non-pre-treated, HP pre-treated, and PEF pre-treated samples, respectively). PEF and HP combined with OD and anti-browning agent enrichment are sought to improve the quality and microbial stability of fresh-cut potatoes during refrigerator storage. Untreated fresh-cut potatoes were characterized by color degradation from the 2nd day of storage at 4 °C, and presented microbial growth (total viable counts: 6 log (CFU)/g) at day 6, whereas pre-treated potato samples retained their color and microbiologically stability after 6 days of cold storage (total viable counts, <4 log(CFU)/g).

Effect of Preliminary Treatment by Pulsed Electric Fields and Blanching on the Quality of Fried Sweet Potato Chips

The effects of pulsed electric fields (PEF) and blanching pretreatments on frying kinetics, oil content, color, texture, acrylamide (AA) content, and microstructure have been investigated in this paper. The total PEF pretreatment duration was t_PEF = 0.2 s with an intensity of E = 1 kV/cm; blanching was studied at 85 °C for 5 min. The results demonstrated that pretreatment significantly reduced the moisture ratio and oil content by 25% and 40.33%, respectively. The total color change ΔE value of the pretreated samples was lower than that of the untreated samples. In addition, pretreatment increased the hardness of the sample after frying, and the AA content in the fried samples pretreated with PEF + blanching was reduced by approximately 46.10% (638 μg/kg). Finally, fried sweet potato chips obtained by the combined pretreatment exhibited a smoother and flatter cross-sectional microstructure.

Mitigation of Acrylamide in Potato Chips by Pre-drying and Pulsed Electric Field Treatment

The object of this work was to study the effects of preliminary vacuum drying (VD), pulsed electric field (PEF) treatment, frying temperature on color, oil uptake, and acrylamide (AA) content in fried potato chips. The results of this study indicated that an increase of frying temperature from 120 to 180°C led to a decrease of frying time of around 70% for untreated and PEF pre-treated samples. The color value of L* and a* decreased with the increase of frying temperature, and those values of the sample pre-treated by PEF were significantly higher compared to those obtained from untreated samples. The PEF pre-treatment promoted the reduction of oil content of fried samples by up to 17.6, 14.2, and 16% compared with untreated samples at the frying temperatures of 120, 150, and 180°C, respectively. Higher efficiency was observed by applying the preliminary VD in the case of the frying temperature of 150°C. Furthermore, it was revealed that PEF pre-treatment and preliminary VD application lead to a synergetic effect on the reduction of AA content in potato chips. For example, with the initial moisture ratio of 0.5, pre-dried by VD and pre-treated by PEF, the AA content was noticeably decreased from 2,220 to 311 μg/kg compared to untreated and undehydrated samples at the frying temperature of 150°C. Our findings provide reference for a new pre-treatment to mitigate AA formation and to improve the quality of potato chips.

The Effect of UV-C Irradiation on the Mechanical and Physiological Properties of Potato Tuber and Different Products

Amongst the surface treatment technologies to emerge in the last few decades, UV-C radiation surface treatment is widely used in food process industries for the purpose of shelf life elongation, bacterial inactivation, and stimulation. However, the short wave application is highly dose-dependent and induces different properties of the product during exposure. Mechanical properties of the agricultural products and their derivatives represent the key indicator of acceptability by the end-user. This paper surveys the recent findings of the influence of UV-C on the stress response and physiological change concerning the mechanical and textural properties of miscellaneous agricultural products with a specific focus on a potato tuber. This paper also reviewed the hormetic effect of UV-C triggered at a different classification of doses studied so far on the amount of phenolic content, antioxidants, and other chemicals responsible for the stimulation process. The combined technologies with UV-C for product quality improvement are also highlighted. The review work draws the current challenges as well as future perspectives. Moreover, a way forward in the key areas of improvement of UV-C treatment technologies is suggested that can induce a favorable stress, enabling the product to achieve self-defense mechanisms against wound, impact, and mechanical damage.

Effects of PEF-Assisted Freeze-Drying on Protein Quality, Microstructure, and Digestibility in Chilean Abalone “Loco” (Concholepas concholepas) Mollusk

The purpose of this study was to apply different pulsed electric field (PEF) conditions as a pretreatment to the freeze-drying (FD) process of Chilean abalone and to assess its effects on protein quality, microstructure, and digestibility of the freeze-dried product. The treatments PEF (0.5, 1.0, and 2.0 kV cm⁻¹) and cooking (CO) were applied at 100°C × 15 min. Then, their performances were subjected to a FD process. PEF + CO pretreated freeze-dried samples showed shorter process times than freeze-dried control samples without PEF + CO, where the treatment PEF at 2.0 kV cm⁻¹ reached the shortest time. In addition, the abovementioned samples presented the best textural parameters but a low protein content. The thermal properties indicate a total denaturation of the proteins, where the amide I region presented greater mobility in the sample pretreated with an electric field of 2.0 kV cm⁻¹. The assay for digestibility shows better hydrolysis for the 2.0 kV cm⁻¹ PEF sample and has a higher Computer-Protein Efficiency Ratio (C-PER). Thereby, variations in thermal behavior and physicochemical parameters in comparison to combined PEF + CO pretreatments were observed. In addition, high protein quality and digestibility of pretreated freeze-dried Chilean abalones were maintained to the desired properties (texture and C-PER) and conditions (FD time).

Recent advances in physical fields-based frying techniques for enhanced efficiency and quality attributes

Frying is one of the most common units in food processing and catering worldwide, which involves simultaneous physicochemical and structural changes. However, the problems of traditional frying technology, such as low thermal utilization and poor processing efficiency, have been gradually exposed to industrial production. In this paper, strategies of applying physical fields, such as pressure field, electromagnetic field, and acoustic field in frying technology separately or synergistically with improved efficiency and quality attributes are reviewed. The role of physical fields in the frying process was discussed with modifications in heat and mass transfer and porous structures. The effects of physical fields and their processing parameters on moisture loss kinetics, oil uptake, texture, color, and nutrients retention of fried food are introduced, respectively. Recent advances in multi-physical field-based frying techniques were recommended with synergistic benefits. Furthermore, the trends and challenges that could further develop the multi-physical field-based frying techniques are proposed, showing further commercial prospects for the purpose. The application of physical fields has brought new inspiration to the exploitation of efficient and high-qualified frying technologies, while higher technical levels and economic costs need to be taken into consideration. HighlightsThe role of physical fields in pretreatments and frying process were reviewed.The mechanism of physics fields on frying efficiency and quality was summarized.The physicochemical and microstructure changes by physics fields were discussed.The synergy of physical fields in frying technology were outlined.The trends for further multi-physical field-based frying techniques were proposed.

The application of PEF technology in food processing and human nutrition

During the last decades, many novel techniques of food processing have been developed in response to growing demand for safe and high quality food products. Nowadays, consumers have high expectations regarding the sensory quality, functionality and nutritional value of products. They also attach great importance to the use of environmentally-friendly technologies of food production. The aim of this review is to summarize the applications of PEF in food technology and, potentially, in production of functional food. The examples of process parameters and obtained effects for each application have been presented.

Understanding the Frying Process of Plant-Based Foods Pretreated with Pulsed Electric Fields Using Frying Models

Deep-fried foods (e.g., French fries, potato/veggie crisps) are popular among consumers. Recently, there has been an increased interest in the application of Pulsed Electric Fields (PEF) technology as a pretreatment of plant-based foods prior to deep-frying to improve quality (e.g., lower browning tendency and oil uptake) and reduce production costs (e.g., better water and energy efficiencies). However, the influence of a PEF pretreatment on the frying process and related chemical reactions for food materials is still not fully understood. PEF treatment of plant tissue causes structural modifications, which are likely to influence heat, mass and momentum transfers, as well as altering the rate of chemical reactions, during the frying process. Detailed insights into the frying process in terms of heat, mass (water and oil) and momentum transfers are outlined, in conjunction with the development of Maillard reaction and starch gelatinisation during frying. These changes occur during frying and consequently will impact on oil uptake, moisture content, colour, texture and the amount of contaminants in the fried foods, as well as the fried oil, and hence, the effects of PEF pretreatment on these quality properties of a variety of fried plant-based foods are summarised. Different mathematical models to potentially describe the influence of PEF on the frying process of plant-based foods and to predict the quality parameters of fried foods produced from PEF-treated plant materials are addressed.