RESUMO
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.
Assuntos
Manipulação de Alimentos , Conservantes de Alimentos/química , Qualidade dos Alimentos , Armazenamento de Alimentos , Frutas/química , Reação de Maillard , Malus/química , Catecol Oxidase/antagonistas & inibidores , Catecol Oxidase/metabolismo , Ácido Clorogênico/efeitos adversos , Ácido Clorogênico/antagonistas & inibidores , Temperatura Baixa , Cruzamentos Genéticos , Inibidores Enzimáticos/química , Frutas/efeitos dos fármacos , Frutas/enzimologia , Humanos , Reação de Maillard/efeitos dos fármacos , Malus/efeitos dos fármacos , Malus/enzimologia , Oxidantes/efeitos adversos , Oxidantes/antagonistas & inibidores , Proteínas de Plantas/antagonistas & inibidores , Proteínas de Plantas/metabolismo , Polifenóis/análise , Sensação , Cloreto de Sódio/química , Fluoreto de Sódio/química , Propriedades de SuperfícieRESUMO
Chlorogenic acid (CGA) induced apoptotic cell death in human oral squamous cell carcinoma (HSC-2) and salivary gland tumor (HSG) cell lines. CGA exhibited oxidation potential in the culture medium, as demonstrated by NO monitor. Both cytotoxic activity and oxidation potential were significantly reduced by the addition of CoCl2. ESR spectroscopy showed that CGA produced seven peaks of radicals under alkaline condition, while addition of CoCl2 altered the spectral pattern and diminished the radical intensity of CGA. CoCl2 accelerated the CGA-induced coloration of the culture medium and modified the difference spectrum at around 325 nm, an absorption maximum characteristic of CGA. These data suggest that CoCl2 induced conformational changes in the CGA molecule.
