Effect of Sugars and Maillard Reaction Products on Polyphenol Oxidase and Peroxidase Activity in Food

Abstract

The effect of glucose, fructose and sucrose aqueous solutions on polyphenol oxidase (PPO) and peroxidase (POD) activity was studied. Solutions with high concentrations of sugars showed a slight inhibiting effect on PPO while an activation was observed for POD. Glucose solutions, tested after sufficient heat treatments, showed an inhibiting action only on PPO activity. Maillard reaction products, obtained by heating a glucose/glycine solution, caused an unexpectedly strong inhibiting effect on both enzymes. The inhibition became more evident with increasing heating times of the glucose/glycine solution, reducing the activity of PPO and POD nearly to zero. Thus, the Maillard reaction products, already known for their antioxidant properties, were also shown to have a strong inhibiting effect on enzymatic browning.

Interaction between Maillard reaction products and lipid oxidation in starch-based model systems

“…The browning kinetics in the different model systems considered was studied using the following indicators: optical density at 420 nm; 20 Hunter L* and a* values. 21 The changes in optical density at 420 nm and Hunter L* and a* values in the samples belonging to models A, B, C and D during the heating time are reported in Fig 1. As expected, the samples without glucose and lysine (C and D) do not show any colour change.…”

“…A high-performance liquid chromatograph (Jasco 880PU, Tokyo, Japan) equipped with a manual 10 ml loop injector, a refractive index detector (RI-3, Varian, Sunnyvale, USA) and a recorder (Varian 4290, USA) was used. The analysis was carried out using a 250 mm  4 mm Lichrosorb NH 2 Hibar RT 250-4 prepacked column (Merck, Dorset, UK) with acetonitrile/water (80: 20) as mobile phase at a¯ow rate of 1.5 ml min À1 . For HPLC analysis, 5 g of each sample was suspended in 30 ml of distilled water and homogenised using a Politron (PT 3000, Kinematica AG, Littau, Switzerland) for 1 min.…”

Effect of calcium soil amendments on phenolic compounds and soft rot resistance in potato tubers

“…The leaves were pooled to make a composite 6 sample. The assay was carried out according to the method described by Thypyapong et al (1995) and activity assayed as described by Nicoli et al (1991), measured by the change in assay mixture at 30ºC at A 370 . Activity was based on the enzymatic oxidation of caffeic acid.…”

Polyphenoloxidase inactivation by light exposure in model systems and apple derivatives

“…Polyphenoloxidase activity in apple slices was detected on their extracts, which were prepared according to the methodology described by Nicoli, Elizalde, Pitotti, and Lerici (1991). Extracts were obtained by blending (Polytron PT 3000 Kinematica AG, Littau, Swiss) 1: 1 (w/w) apple slices with 0.1 M phosphate-citrate buffer at pH 4.0.…”