Pulsed electric field technology in the manufacturing processes of wine, beer, and rice wine: A review

Pulsed electric field processing of white grapes (cv. Garganega): Effects on wine composition and volatile compounds

Pulsed electric field (PEF) processing of white grapes (cv. Garganega) after crushing was studied on pilot-plant scale, to investigate the effects of the treatment on must and wine composition, wine color and predisposition to browning, wine aroma compounds and extraction of aroma precursors from grapes. PEF pre-treatment of grapes did not change the must or wine basic composition, nor was it able to modify the evolution of alcoholic fermentation. By contrast, PEF produced an increase in total dry extract, wine color and total phenolics. Treatment corresponding to a total specific energy of 22 kJ kg^-1 allowed more intense extraction of varietal aroma precursors without provoking excessive color evolution and extraction of phenolic compounds, apparently increasing the stability of wine towards oxidation. Due to the few papers available on this subject, PEF applications on white grapes should be optimized in further experiments.

Optimum Conversion of Major Ginsenoside Rb1 to Minor Ginsenoside Rg3(S) by Pulsed Electric Field-Assisted Acid Hydrolysis Treatment

Ginsenoside Rg3(S) is a primary bioactive component in ginseng, which has pharmacological effects and nutritional activities. In the present study, pulsed electric field (PEF)-assisted acid hydrolysis processing was used to convert major ginsenoside Rb1 to minor ginsenoside Rg3(S). The optimum parameters of PEF assisted acid hydrolysis were analyzed by response surface methodology (RSM). The optimum processing conditions were: electric field intensity, 20 kVcm−1; acid concentration, 0.25 mol/L; pulse number, 10. The conversion rate of ginsenoside Rg3(S) achieved 68.58%, in accordance to the predicted value. The structure of hydrolyzed product was confirmed by 13C-NMR. The results suggested that PEF-assisted acid hydrolysis significantly enhanced conversion rate of ginsenoside Rg3(S).

Recent Advances and Applications of Pulsed Electric Fields (PEF) to Improve Polyphenol Extraction and Color Release during Red Winemaking

Pulsed electric fields (PEF) technology is an innovative food processing system and it has been introduced in relatively recent times as a pre-treatment of liquid and semi-solid food. Low cost-equipment and short processing time, coupled to the effectiveness in assisting the extraction of valuable compounds from vegetable tissues, makes PEF a challenging solution for the industrial red winemaking; a tailored PEF-assisted maceration was demonstrated to promote an increase in wine color quality and an improvement in the polyphenolic profile. Despite the application of PEF has been studied and the positive effects in selected wine varieties were demonstrated on batch and pilot-scale systems, there is a need for a more detailed characterization of the impact in different grapes, and for a better understanding of potential undesirable side-effects. This review aims to summarize the state of the art in view of a detailed feasibility study, to promote the introduction of PEF technology in the oenological industry.

Landmarks in the historical development of twenty first century food processing technologies

Over a course of centuries, various food processing technologies have been explored and implemented to provide safe, fresher-tasting and nutritive food products. Among these technologies, application of emerging food processes (e.g., cold plasma, pressurized fluids, pulsed electric fields, ohmic heating, radiofrequency electric fields, ultrasonics and megasonics, high hydrostatic pressure, high pressure homogenization, hyperbaric storage, and negative pressure cavitation extraction) have attracted much attention in the past decades. This is because, compared to their conventional counterparts, novel food processes allow a significant reduction in the overall processing times with savings in energy consumption, while ensuring food safety, and ample benefits for the industry. Noteworthily, industry and university teams have made extensive efforts for the development of novel technologies, with sound scientific knowledge of their effects on different food materials. The main objective of this review is to provide a historical account of the extensive efforts and inventions in the field of emerging food processing technologies since their inception to present day.

Fermentation at non-conventional conditions in food- and bio-sciences by the application of advanced processing technologies

The interest in improving the yield and productivity values of relevant microbial fermentations is an increasingly important issue for the scientific community. Therefore, several strategies have been tested for the stimulation of microbial growth and manipulation of their metabolic behavior. One promising approach involves the performance of fermentative processes during non-conventional conditions, which includes high pressure (HP), electric fields (EF) and ultrasound (US). These advanced technologies are usually applied for microbial inactivation in the context of food processing. However, the approach described in this study focuses on the use of these technologies at sub-lethal levels, since the aim is microbial growth and fermentation under these stress conditions. During these sub-lethal conditions, microbial strains develop specific genetic, physiologic and metabolic stress responses, possibly leading to fermentation products and processes with novel characteristics. In some cases, these modifications can represent considerable improvements, such as increased yields, productivities and fermentation rates, lower accumulation of by-products and/or production of different compounds. Although several studies report the successful application of these technologies during the fermentation processes, information on this subject is still scarce and poorly understood. For that reason, the present review paper intends to assemble and discuss the main findings reported in the literature to date, and aims to stimulate interest and encourage further developments in this field.

Antioxidant Activity Improvement and Evaluation of Structure Changes of SHECN Treated by Pulsed Electric Field (PEF) Technology

The purpose of the study was to evaluate the relationship between antioxidant activity improvement and structure changes of peptide (Ser-His-Glu-Cys-Asn (SHECN) isolated from soybean treated by pulsed electric field (PEF). The two-factor-at-a–time (TFAT) was performed to investigate interaction of electric field intensity (5, 10, 15 and 20 kV/cm) and pulse frequency (1,800 and 2,400 Hz) on antioxidant activity improvement and structure changes. Compared with untreated peptide, DPPH radical inhibition of SHECN was significantly increased to 95.54 ± 0.16 % at optimal conditions (electric field intensity 15 kV/cm, pulse frequency 1,800 Hz and a retention time of 2 h). Results showed that the primary structure of SHECN had not been changed based on the nuclear magnetic resonance analysis. However, the secondary structure of peptide, especially α-helix can be changed. These results suggested that mechanism of antioxidant activity improvement is related to secondary structure changes.