Spectral alteration and degradation of cyanidin-3-glucoside exposed to pulsed electric field

Effect of pulsed electric field processing on reduction of sulfamethazine residue content in milk

The whole milk spiked with sulfamethazine was treated under thermal and pulsed electric field processing for maximum reduction. The low-temperature long-time (LTLT, 62.5 °C for 30 min), high-temperature short time (HTST, 72 °C for 15 s) pasteurization and ultra-high temperature processing (UHT, 138 °C for 2 s) resulted in the reduction of sulfamethazine 7.3, 5.2 and 4.6% respectively. PEF and combination treatment (thermal + PEF) were found to reduce sulfamethazine content in milk by 67-72% and 73-76% respectively. Combined treatment of milk resulted in a higher percentage of reduction. Similar predicted and actual values proved that they fit the linear regression model and successful application of pulsed electric field technology in reducing antibiotic residues. PEF and mild thermal treatment can be a promising technology to reduce the antibiotic residues with ensuring minimal negative impact on the nutritional quality of food.

Impact of pulsed electric field processing on reduction of benzylpenicillin residue in milk

PURPOSE

The presence of residues of veterinary drugs in animal-derived food is one of the major problems for food safety. The consumption of milk containing antibiotic residues can evoke allergic reactions in hypersensitive individuals, disorders of intestinal flora and produces the risk of emerging antibiotic resistance microorganism.

METHODS

In this study, the effect of the thermal treatments and pulsed electric field (PEF) on the reduction of benzylpenicillin (PNG) spiked artificially in milk was evaluated quantitatively by calculating the loss of the concentration using HPLC. Fresh raw milk was subjected to a high-temperature short-time (72 °C for 15 s, HTST), low-temperature long- time (62.5 °C for 30 min, LTLT) and ultrahigh-temperature processing (138 °C for 2 s, UHT). The PEF process factors output voltage (20-65%) and pulse width (10-26 μs) were optimized for maximum reduction of PNG by employing the statistical tool response surface methodology (RSM).

RESULTS

HTST, LTLT, and UHT have resulted in the reduction of PNG 13.5%, 6.1%, 1.2% respectively. The optimized parameters of the PEF treatment had reduction efficiency in the range of 79-86%. The saddle response surface obtained from RSM showed that the center was neither at maximum point nor at the minimum point. The predicted and experimental values of the response were nearly similar which proved the suitability of the fitted quadratic model. Combined thermal and PEF treatment has a significant synergistic effect in reducing the PNG.

CONCLUSIONS

PEF induced reduction efficiency achieved was 79-86%. The reduction percentages were observed higher in the combined pasteurization and PEF treatment of milk. The pulsed electric field can be adopted as a unique processing tool for degradation of antibiotic residues whilst retaining nutritional quality parameters.

Anthocyanins Recovered from Agri-Food By-Products Using Innovative Processes: Trends, Challenges, and Perspectives for Their Application in Food Systems

Anthocyanins are naturally occurring phytochemicals that have attracted growing interest from consumers and the food industry due to their multiple biological properties and technological applications. Nevertheless, conventional extraction techniques based on thermal technologies can compromise both the recovery and stability of anthocyanins, reducing their global yield and/or limiting their application in food systems. The current review provides an overview of the main innovative processes (e.g., pulsed electric field, microwave, and ultrasound) used to recover anthocyanins from agri-food waste/by-products and the mechanisms involved in anthocyanin extraction and their impacts on the stability of these compounds. Moreover, trends and perspectives of anthocyanins' applications in food systems, such as antioxidants, natural colorants, preservatives, and active and smart packaging components, are addressed. Challenges behind anthocyanin implementation in food systems are displayed and potential solutions to overcome these drawbacks are proposed.

Degradation kinetics of anthocyanin and physicochemical changes in fermented turnip juice exposed to pulsed UV light

In this study, the effects of pulsed UV (PUV) light on the degradation kinetics of anthocyanins and physicochemical properties of turnip juice were investigated. PUV light was applied to turnip juice at 3 different distances (5, 8, 13 cm) from the quartz window of the xenon lamp for 5 different times (5, 15, 30, 45, 60 s). The pH, total acidity (% lactic acid), monomeric anthocyanin content, color density, hue, brightness, and percent color components (yellow, red, and blue) of turnip juice changed significantly after PUV-light treatments at each level. The maximum degradation of anthocyanin after PUV-light treatments was found to be about 63%. The anthocyanin degradation, brightness, yellow and blue color (%) increased, while red color (%) decreased with longer treatment time and shorter distance. The degradation of monomeric anthocyanins in turnip juice exposed to PUV light was described by the Weibull model (R² 0.982-0.998, RMSE 0.087-0.133) more accurately than the first-order kinetics (R² 0.906-0.992, RMSE 0.071-0.192).

Analysis of α-helix unfolding in the pine nut peptide Lys-Cys-His-Lys-Pro induced by pulsed electric field

BACKGROUND

A variety of analytical techniques were applied to explore the effects of pulsed electric field (PEF) on α-helix structural changes in the novel antioxidant peptide Lys-Cys-His-Lys-Pro (KCHKP, 611.76 Da).

RESULTS

The relative α-helix content of the KCHKP peptide was significantly altered from 100% to 89.91 ± 0.97% when the electric pulse frequency was 1800 Hz and the field intensity was 10 kV cm^-1 . Moreover, the 1,1-diphenyl-2-pycryl-hydrazyl (DPPH) and 2,2-azinobis diammonium salt (ABTS) radical-scavenging activities of PEF-treated KCHKP were increased from 56.31% ± 0.74% to 84.33% ± 1.23% and from 40.56% ± 0.78% to 51.33% ± 0.27%, respectively.

CONCLUSION

PEF treatment increased peptide linkage stretch vibration and altered hydrogen bonding of KCHKP. The stability of the α-helix structure was influenced by hydrogen bonds within the peptide linkage of KCHKP induced by PEF and was related to changes in antioxidant activity. © 2017 Society of Chemical Industry.

Anthocyanin concentration depends on the counterbalance between its synthesis and degradation in plum fruit at high temperature

Anthocyanin synthesis and degradation processes were analyzed at transcript, enzyme, and metabolite levels to clarify the effects of high temperature on the concentration of anthocyanin in plum fruit (Prunus salicina Lindl.). The transcript levels of PsPAL, PsCHS, and PsDFR decreased while those of PsANS and PsUFGT were similar at 35 °C compared with 20 °C. The activities of the enzymes encoded by these genes were all increased in fruits at 35 °C. The concentrations of anthocyanins were higher at 35 °C on day 5 but then decreased to lower values on day 9 compared with that at 20 °C. Furthermore, high temperature (35 °C) increased the concentration of hydrogen peroxide and the activity of class III peroxidase in the fruit. The concentration of procatechuic acid, a product of the reaction between anthocyanin and hydrogen peroxide, hardly changed at 20 °C but was significantly increased at 35 °C on day 9, indicating that anthocyanin was degraded by hydrogen peroxide, which was catalyzed by class III peroxidase. Based on mathematical modeling, it was estimated that more than 60-70% was enzymatically degraded on day 9 when the temperature increased from 20 °C to 35 °C. We conclude that at the high temperature, the anthocyanin content in plum fruit depend on the counterbalance between its synthesis and degradation.

Sonodegradation of cyanidin-3-glucosylrutinoside: degradation kinetic analysis and its impact on antioxidant capacity in vitro

BACKGROUND

As an alternative preservation method for thermal treatment, ultrasound comprises a novel non-thermal processing technology that can significantly avoid undesirable nutritional changes. However, the recent literature indicates that anthocyanin degradation occurs when ultrasound is applied in juice at high amplitude parameters. Such work has mainly focussed on the effect of ultrasound on stability, the antioxidant capacity of cyanidin-3-glucosylrutinoside (Cy-3-glc-rut) and the correlation between anthocyanin degradation and ·OH generation in a simulated system.

RESULTS

The spectral intensities of Cy-3-glc-rut at 518 and 282 nm decreased with increasing ultrasound power and treatment time. The degradation of Cy-3-glc-rut was consistent with first-order reaction kinetics (r²  > 0.9000) and there was a good linear correlation between anthocyanin degradation and hydroxyl radical formation induced by ultrasound (r²  = 0.9258). Moreover, a decrease in the antioxidant activity of Cy-3-glc-rut after ultrasound evaluated by the 1,1-diphenyl-2-picrylhydrazyl and ferric reducing antioxidant power methods was observed.

CONCLUSION

Overall, the results of the present study show that ultrasound will accelerate the degradation of Cy-3-glc-rut with the growth of power over time. © 2016 Society of Chemical Industry.

Stability, Antioxidant Capacity and Degradation Kinetics of Pelargonidin-3-glucoside Exposed to Ultrasound Power at Low Temperature

As an alternative preservation method to thermal treatment, ultrasound is a novel non-thermal processing technology that can significantly avoid undesirable nutritional changes. However, recently literature indicated that anthocyanin degradation occurred when high amplitude ultrasound was applied to juice. This work mainly studied the effect of ultrasound on the stability and antioxidant capacity of pelargonidin-3-glucoside (Pg-3-glu) and the correlation between anthocyanin degradation and •OH generation in a simulated system. Results indicated that the spectral intensities of Pg-3-glu decreased with increasing ultrasound power (200–500 W) and treatment time (0–60 min). The degradation trend was consistent with first-order reaction kinetics (R² > 0.9100). Further study showed that there was a good linear correlation between Pg-3-glu degradation and •OH production (R² = 0.8790), which indicated the important role of •OH in the degradation of anthocyanin during ultrasound exposure. Moreover, a decrease in the antioxidant activity of solution(s) containing Pg-3-glu as evaluated by the DPPH and FRAP methods was observed after ultrasound treatment.

Reduction of diazinon and dimethoate in apple juice by pulsed electric field treatment

BACKGROUND

Organophosphorus pesticides (OPPs) are widely used in agricultural production in China, and residues of OPPs in agro-products and foods have become a public health concern. Chronic exposure to OPPs can result in potential immunosuppressive effects, cytotoxicity and mutagenicity. Pulsed electric fields (PEFs) have the potential to be used as an alternative to conventional techniques of food production. The aim of the present study was to investigate the influence of PEFs on the degradation of diazinon and dimethoate added to apple juice.

RESULTS

PEF treatment significantly promoted the degradation of both pesticides (P < 0.05). The extent of degradation was strongly influenced by the electric field strength and treatment time, and maximum degradation of both diazinon (47.6%) and dimethoate (34.7%) was achieved by treatment at 20 kV cm⁻¹ for 260 µs. The degradation behaviour of the pesticides was described by Weibull and Hülsheger models, both of which successfully fitted the degradation of diazinon and dimethoate. In addition, the decline in the toxicity of samples was observed with a photobacterium bioassay.

CONCLUSION

PEF treatment was effective in eliminating residues of diazinon and dimethoate spiked in apple juice and in mitigating sample toxicity.