Effect of halide salts on development of surface browning on fresh-cut 'Granny Smith' (Malus × domestica Borkh) apple slices during storage at low temperature.

BACKGROUND: The postharvest life of fresh-cut apple slices is limited by browning on cut surfaces. Dipping in halide salt solutions was examined for their inhibition of surface browning on 'Granny Smith' apple slices and the effects on biochemical factors associated with browning. RESULTS: Delay in browning by salts was greatest with chloride = phosphate > sulfate > nitrate with no difference between sodium, potassium and calcium ions. The effectiveness of sodium halides on browning was fluoride > chloride = bromide > iodide = control. Polyphenol oxidase (PPO) activity of tissue extracted from chloride- and fluoride-treated slices was not different to control but when added into the assay solution, NaF > NaCl both showed lower PPO activity at pH 3-5 compared to control buffer. The level of polyphenols in treated slices was NaF > NaCl > control. Addition of chlorogenic acid to slices enhanced browning but NaCl and NaF counteracted this effect. There was no effect of either halide salt on respiration, ethylene production, ion leakage, and antioxidant activity. CONCLUSION: Dipping apple slices in NaCl is a low cost treatment with few impediments to commercial use and could be a replacement for other anti-browning additives. The mode of action of NaCl and NaF is through decreasing PPO activity resulting in reduced oxidation of polyphenols.

Encapsulation artocarpanone and ascorbic acid in O/W microemulsions: Preparation, characterization, and antibrowning effects in apple juice.

The aim of this study is to improve artocarpanone solubility by developing an O/W microemulsion with the evaluation of its antibrowning effects. The chemical and physical stabilities as well as antibrowning effects in apple juice were also evaluated. The formulation of artocarpanone microemulsion consisted of 4% w/w of ethyl butyrate, 10.67% w/w of Tween 80, 5.33% w/w of polyethylene glycol 400, and 80% w/w of water, with a maximum solubility of artocarpanone up to 10.54 ± 0.01 mg/mL, at least 3000-folds increase in solubility compared that in water. Encapsulating artocarpanone and ascorbic acid (VC) into microemulsion simultaneously decreased modest artocarpanone solubility whereas improving its stability in long-term storage. Blank, artocarpanone and artocarpanone-Vc-loaded microemulsions demonstrated steadily during accelerated and long-term storage. Artocarpanone-Vc-loaded microemulsion showed strong antibrowning effects in apple juice at room temperature in 24h, suggesting that artocarpanone-Vc-loaded microemulsion is a good antibrowning agent for apple juices.

Effects of 3-deoxyglucosone on the Maillard reaction.

We investigated the effect of exogenously applied 3-deoxyglucosone, a major carbonyl intermediate, on the Maillard reaction. The fluorescence intensity of the product of the reaction of bovine serum albumin with 3-deoxyglucosone was higher than that with an equivalent amount of glucose. Similarly the rate of polymerization of lysozyme in the presence of 3-deoxyglucosone was also greater than with glucose, and collagen incubated with 3-deoxyglucosone was less digestible than collagen incubated with glucose. By contrast, aminoguanidine inhibited an increase in fluorescence of the Maillard compounds and the polymerization of protein, both of which were stimulated by 3-deoxyglucosone. These results suggest that 3-deoxyglucosone accelerates the advanced stage of the Maillard reaction and that aminoguanidine acts on 3-deoxyglucosone to inhibit its action in the advanced stage of the Maillard reaction.