Polyphenol oxidase (PPO) activity, proximate composition, and phytochemicals were determined in four common Irish potato cultivars following a high pressure processing (HPP) at 600 MPa for 3 min. PPO activity was significantly (p < 0.05) lower in all HPP treated samples, while the overall proximate composition was not affected. The total phenolic content was significantly higher in the HPP treated samples. Chlorogenic acid levels significantly decreased with simultaneous increase of caffeic acid and p-coumaric acid levels upon HPP treatment. No significant changes were observed in rutin and ferulic acid levels, although their levels varied, depending on the potato cultivars, while the levels of cytotoxic glycoalkaloids (α-solanine and α-chaconine) remained unaltered.
The bioaccumulation of heavy metals in food tubers (carrots, onions, and potatoes) as a result of polluted irrigation water has been studied in this review paper. Given that heavy metals can cause a considerable oxidative stress, the impact of these metals to the physiology of the plants has also been assessed. The consumption of vegetables crosscontaminated with heavy metals carries a considerable risk for humans (especially for children and pregnant women) and these dietary implications are discussed while European Food Safety Authority has been urged to look into this matter of concern.
Please cite this article as: Tsikrika, K., Chu, B.-S., Bremner, D.H., Lemos, M.Adí., The effect of different frequencies of ultrasound on the activity of horseradish peroxidase, Abstract 6Ultrasound technology has been studied by food researchers as an alternative 7 method for thermal processing. The use of ultrasound as a way to inactivate and/or 8 activate enzymes has been widely studied at low frequencies (20-40 kHz), however, 9 little research on the effect of high frequencies has been reported. Thus, the effect 10 of high and low frequency ultrasound on commercial horseradish peroxidase with a 11 concentration of 0.005 mg mL -1 is described. Experiments were performed for 60 12 minutes using 20, 378, 583, 862, 995, 1144 and 1175 kHz ultrasound at power levels 13 (acoustic energy) between 2.1 to 64 W. Residual activity was monitored using a 14 spectrophotometric method and data analysis was performed using ANOVA. A 15 significant enhancement of enzyme inactivation (p<0.05) was observed at each 16 frequency with an increase of sonication time and power. Inactivation of peroxidase 17 by ultrasound followed first order kinetics and an increase of the rate constant with 18 the power applied was observed for all the frequencies studied. Overall, low 19 frequency (20 kHz) and low power are not effective on the enzyme inactivation and 20 the level of residual activity remained high. The use of 378 and 583 kHz (48 W) is 21 particularly effective for complete enzyme inactivation. 22 ACCEPTED MANUSCRIPT 2
The effect of High Pressure Processing (HPP) on Irish potato cultivars’ antioxidant activity (AOA) was examined. High Pressure Processing at 600 MPa for 3 min was applied to two coloured (Rooster and Kerr’s Pink) and two white (Saxon and Gemson) Irish potato varieties. Antioxidant activity was assayed spectrophotometrically by ferric reducing antioxidant power and diphenyl-1-picrylhydrazyl methods. No statistically significant (p ≥ 0.05) change in antioxidant activity was observed in both the AOA methods irrespective of the HPP treatments, although a slight increase in the activity was noted in the majority of the HPP treated samples. This implies that HPP treatment has little role in improving the functional qualities, and can be tailored to improve the quality and safety of the commonly consumed potatoes.
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