Sulfur‐Containing Compounds Heated under Alkaline Condition: Antibrowning, Antioxidative Activities, and Their Effect on Quality of Shrimp during Iced Storage

Abstract

Sulfur-containing compounds heated under alkaline condition (pH 10) were determined for inhibitory activity toward polyphenol oxidase (PPO) from Pacific white shrimp (Litopenaeus vannamei) and for antioxidative activity. Cysteine and glutathione (GSH) (20 mM) heated at 100 degrees C at pH 10 strongly inhibited PPO activity. Heated alkaline cysteine showed the greater 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 2,2-diphenyl-1-picryl hydrazyl (DPPH) radical scavenging activity, copper-chelating activity and reducing power than cysteine and glucose-cysteine Maillard reaction products (P < 0.05). Effect of heated alkaline cysteine at different concentrations (0, 20, and 100 mM) on the quality changes of Pacific white shrimp during iced storage was investigated. Shrimp treated with 100 mM heated alkaline cysteine had the lowest melanosis score, thiobarbituric acid-reactive substances (TBARS) value and total viable count (TVC), compared with those without treatment and treated with 20 mM heated alkaline cysteine, throughout the storage of 12 d (P < 0.05). Therefore, heated alkaline cysteine can be used as a novel additive to retard melanosis and extend the quality of postmortem shrimp.

Correlating enzymatic browning inhibition and antioxidant ability of Maillard reaction products derived from different amino acids

“…Cys is the only amino acid that can inhibit enzymatic browning by itself by combining with o ‐quinone, the initial product of enzymatic browning, to produce addition compound . It was also reported that Cys (20 mmol L –1 ) heated alone at 100 o C under alkaline conditions (pH 10) led to a a stronger BIC for Pacific white shrimp during storage than untreated Cys and MRPs of Cys (20 mmol L –1 ) and glucose (20 mmol L –1 ) heated at 100 o C for 12 h . However, the other two sulfur‐containing amino acids cystine and Met showed limited inhibition capacity.…”

“…On the one hand, Billaud et al 30 reported that heating the mixture of Met (0.25 mol L -1 ) and glucose (0.25 mol L -1 ) at 103 o C for 14 h resulted in almost no inhibitory effects on apple PPO, whereas MRPs of Cys and Cys-methylester showed very potent inhibitory activity, and it was suggested that the presence of free thiol group is essential for the generation of strong inhibitory activity for MRPs. On the other hand, Phonpala et al 29 reported a limited inhibition ability of MRPs of Met (20 mmol L -1 ) prepared at 100 o C for 12 h with equimolar glucose on enzymatic browning of shrimp, with inhibition being approximately 15% with a 5 mmol L -1 equivalent amino acid concentration (as calculated from the data in the original study). During the present study, MRPs of Met and glucose inhibited 51% enzymatic browning catalyzed by mushroom tyrosinase at a concentration of 2.083 mmol L -1 .…”

Activity of Fusion Prophenoloxidase-GFP and Its Potential Applications for Innate Immunity Study

“…Insect PPO belongs to type 3 copper-containing proteins that extensively exist in mammals, insects, shrimp, plants and microbes [3]–[7]. The biochemical properties of insect PPOs are conserved.…”

“…PPO is a copper-containing enzyme that oxidizes mono-phenols to produce melanins [1], [2]. This family of proteins exist in microbes, plants, invertebrate and vertebrate animals [3]–[7], and each of them has some specific functions. Insect PPO is a very important innate immunity protein that can induce melanization of microbes and parasites thereby quickly and effectively eliminating them [1], [3], [8]–[10].…”

Fluorescence Evaluation of Scavenging Efficiency of Antioxidants Against Reactive Oxygen Species (ROS) in Cigarette Smoke

“…The reducing capacity of the various antioxidants was evaluated according to the reported method with some modifications (Phonpala et al 2009). Different concentrations (1-40 mg=mL) of antioxidants prepared in ethanol (1 mL) were mixed with 1 mL of sodium phosphate buffer (0.2 M, pH 6.6) and 1 mL (1%) of potassium ferricyanide [K 3 Fe(CN) 6 ].…”