Impact of PEF treatment on quality parameters of white asparagus (Asparagus officinalis L.)

Asparagus (Asparagus racemosus L.) roots: nutritional profile, medicinal profile, preservation, and value addition

Asparagus (Asparagus racemosus L.) is one of the most significant traditional medicinal plants, containing phytochemicals that are non-nutritive but beneficial to health. It contains bioactive metabolites such as fructo-oligosaccharides, polysaccharides, asparosides, shatavarins, sapogenins, racemosols, isoflavones, glycosides, mucilage, and fatty acids, while saponin is one of the main active constituents of asparagus roots. Asparagus helps in fertility promotion, stress management, and hormone modulation. It also treats stomach ulcers, kidney disorders, and Alzheimer's disease. Substitution of asparagus powder or extract for value addition of food products (such as beverages, bakery, and milk) enhances the nutritional and functional properties. Currently, the plant is considered endangered in its natural habitat because of its destructive harvesting, habitat destruction, and deforestation. As it is a highly perishable commodity, it needs proper handling, preservation, and storage. This review will outline the medicinal properties, uses, value addition, and preservation techniques of asparagus roots. The study found that, till now, the only preservation techniques used to increase the shelf life of asparagus roots are drying and irradiation. © 2022 Society of Chemical Industry.

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.

Selected Quality Parameters of Air-Dried Apples Pretreated by High Pressure, Ultrasounds and Pulsed Electric Field-A Comparison Study

The aim of this work was to compare selected physicochemical properties of air dried ‘Golden Delicious’ apples, pretreated either by high-pressure processing (HPP), ultrasound (US) or pulsed electric field (PEF). Following parameters of pretreatment were used: HPP–400 MPa for 15 min, US–21 kHz, 180 W for 45 min, PEF–1 kV/cm, 3.5 kJ/kg. The quality of materials was evaluated by their rehydration properties, hygroscopicity, color and total phenolic content. To compare the effectiveness of the utilized methods, determined properties were expressed as relative comparison values against the reference sample obtained without any pretreatment in the same conditions. The performed research demonstrated that properties can be shaped by the application of proper pretreatment methods. For instance, PEF was shown to be the best method for improving water uptake during rehydration, whereas HPP was the most effective in decreasing hygroscopic properties in comparison with untreated dried apples. Among the investigated methods, HPP resulted in the deepest browning and thus total color difference, while the effects of US and PEF were comparable. For all pretreated dried apples, the total phenolic content was lower when compared with reference material, though the smallest drop was found in sonicated samples.

Changes in the Glutinous Rice Grain and Physicochemical Properties of Its Starch upon Moderate Treatment with Pulsed Electric Field

Pulsed electric field (PEF) processing is an emerging non-thermal technology that shows potential to improve food quality and to maintain stability. Glutinous rice is composed mainly of amylopectin and has low amylose content. This study investigated the effect of PEF treatment at 3 kV/cm field strength for 50 to 300 pulses on whole, water-soaked glutinous rice grains. Micro-pores were created at the surface of PEF treated rice grains, increasing grain porosity from 7.3% to 9.8%. Peak viscosity of PEF treated rice flour decreased, and breakdown, final and setback viscosities increased as the number of PEF treating pulses increased, indicating that the swelling degree of rice starch was promoted after PEF treatment. Lower values of gelatinization enthalpy and lower crystalline degree of PEF treated glutinous rice flour were also observed. Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) studies confirmed the secondary structure changes in rice protein and partial gelatinization of rice starch after PEF treatment.

Impact of Pulsed Electric Fields on the Volatile Compounds Produced in Whole Onions (Allium cepa and Allium fistulosum)

The objective of this research was to investigate the effect of pulsed electric field (PEF) processing on the volatile compounds produced in onion cultivars. The changes in the volatile compounds of onions were assessed comparing results observed while measured immediately and 24 h after PEF treatment using headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS). Significant increases in the concentrations of propanethial S-oxide, propenyl propyl thiosulfinate, 2-methyl-2-pentenal, dipropyl disulfide, propenyl propyl disulfide, methyl propyl disulfide, and methyl propenyl disulfide were observed immediately after PEF treatment. The concentrations of propenyl propyl thiosulfinate, dipropyl disulfide, methyl propyl disulfide, dipropyl trisulfide, methyl propyl trisulfide, and propenyl propyl trisulfide increased after 24 h compared to initial concentrations. It is postulated that these changes are due to PEF-induced cell permeabilisation that facilitates enzyme-substrate reactions after the PEF treatment.

Emerging technologies for the pretreatment of lignocellulosic biomass

Pretreatment of lignocellulosic biomass to overcome its intrinsic recalcitrant nature prior to the production of valuable chemicals has been studied for nearly 200 years. Research has targeted eco-friendly, economical and time-effective solutions, together with a simplified large-scale operational approach. Commonly used pretreatment methods, such as chemical, physico-chemical and biological techniques are still insufficient to meet optimal industrial production requirements in a sustainable way. Recently, advances in applied chemistry approaches conducted under extreme and non-classical conditions has led to possible commercial solutions in the marketplace (e.g. High hydrostatic pressure, High pressure homogenizer, Microwave, Ultrasound technologies). These new industrial technologies are promising candidates as sustainable green pretreatment solutions for lignocellulosic biomass utilization in a large scale biorefinery. This article reviews the application of selected emerging technologies such as ionizing and non-ionizing radiation, pulsed electrical field, ultrasound and high pressure as promising technologies in the valorization of lignocellulosic biomass.

Energy-efficient biomass processing with pulsed electric fields for bioeconomy and sustainable development

Fossil resources-free sustainable development can be achieved through a transition to bioeconomy, an economy based on sustainable biomass-derived food, feed, chemicals, materials, and fuels. However, the transition to bioeconomy requires development of new energy-efficient technologies and processes to manipulate biomass feed stocks and their conversion into useful products, a collective term for which is biorefinery. One of the technological platforms that will enable various pathways of biomass conversion is based on pulsed electric fields applications (PEF). Energy efficiency of PEF treatment is achieved by specific increase of cell membrane permeability, a phenomenon known as membrane electroporation. Here, we review the opportunities that PEF and electroporation provide for the development of sustainable biorefineries. We describe the use of PEF treatment in biomass engineering, drying, deconstruction, extraction of phytochemicals, improvement of fermentations, and biogas production. These applications show the potential of PEF and consequent membrane electroporation to enable the bioeconomy and sustainable development.

Synergetic Effects of Pulsed Electric Field and Ozone Treatments on the Degradation of High Molecular Weight Chitosan

A synergetic method integrating both pulsed electric field (PEF) and ozone treatment was developed as a novel approach to investigate the degradation of high molecular weight chitosan (Mw=4.5×105 Da). A device integrating both components was designed and assembled for the experiments. Results showed that the highest degradation percentage of chitosan was achieved with PEF/ozone co-treatment generated at experimental conditions of 1.2 L/min of ozone flow rate, 100 mL/min of 0.6% (w/v) chitosan solution flow rate, and 26.7 kV/cm of PEF intensity. The degradation percentage after 60 min PEF treatment was 24.89%, whereas it was improved to 94.89% by ozone treatment for 60 min. Combining the two treatments resulted in enhanced degradation percentage of 99.56%, with low molecular weights sample (Mw<2,500 Da) obtained. FTIR analysis demonstrated that the amide structure of the degradation products was minimally affected by the co-treatment. XRD pattern indicated that the crystallinity of the degradation products decreased. In addition, it could complete dissolve in water after 60 min PEF/ozone co-treatment. These results demonstrated the synergetic PEF/ozone co-treatment as an effective method for degradation of high molecular weight chitosan.