Neno

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Universitat de Lleida Escola Tècnica Superior d’Enginyeria Agrària Departament de Tecnologia d’Aliments

Recubrimientos comestibles y sustancias de origen natural en manzana fresca cortada: Una nueva estrategia de conservación

María Alejandra Rojas Graü
Tesis Doctoral Diciembre, 2006

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BROWNING INHIBITION IN FRESH-CUT ‘FUJI’ APPLE SLICES BYNATURAL ANTIBROWNING AGENTS
M.A. Rojas-Graü, A. Sobrino-López, M.S. Tapia, O. Martín-Belloso Journal of Food Science (2006); 71(1):S59-S65

ABSTRACT

Response surface methodology was used to study the effect of antibrowning agents (4-hexylresorcinol, glutathione, N-acetylcysteine and ascorbic acid) and storage time (14 days) on the color of minimally processed Fuji apples. The selected colorparameters were L*, a*, b*, hue angle (h*) and color difference (∆E*). Storage time had a significant effect on all the studied color parameters (p≤0.05). 4hexylresorcinol showed the most effective individual effect on keeping constant a* values (p≤0.0001). Besides, the interaction of N-acetylcysteine/glutathione was found to have a significant effect (p≤0.05) on maintaining a* values over time.On the other hand, individual treatment with N-acetylcysteine in concentrations higher than 0.75% w/v may be used in order to preserve a* and h*. According to the F-test, 4-hexylresorcinol and N-acetylcysteine (p≤0.05) displayed a significant individual effect on ∆E*, indicating that ∆E* decreased when increasing the concentration of

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these antibrowning agents.Nevertheless, color difference went down when 4hexylresorcinol concentration increased up to 0.5%, but higher concentrations of this agent led to an increase in ∆E* that indicates browning. Key words: fresh-cut apples, antibrowning agents, color, response surface methodology
INTRODUCTION

‘Fuji’ apple (Malus domestica Borkh.), a cross between red “Delicious” and “Ralls Janet”, was introduced in Japanin 1962. Nowadays it is extensively cultivated in the main apple-producing areas of the world. This apple cultivar stands out for its excellent quality and sensory characteristics such as juicy, firm, crispy, fine-grained with a sweet, spicy flavor that has high sugar and low acid content, as well as good storage potential (Stebbins and others 1991; Yoshida and others 1995).

Fresh-cut orminimally processed fruit is an important market in fast development because of their convenience and fresh-like quality. However, it is well known that minimally processed fruits and vegetables are generally more perishable than the original raw materials (Gorny and others 1998; Pittia and others 1999), being prone to surface browning usually caused by oxidase enzymes. Browning and its control havebeen extensively studied and reported in many fruits such as apples, pears and bananas (Rocha and others 1998; Abe and others 1998; Soliva-Fortuny and others 2001; Abbott and Buta 2002). Traditionally, sulphites have been used for prevention of browning. However, their use is limited because of their toxicity (Iyengar and McEvily 1992). On the other hand, consumers are demanding a reduction in theoverall use of chemicals on fresh products and alternative methodologies are being investigated to extend shelf-life of fresh-cut fruits. The use of natural compounds and their derivatives has been found to be

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effective in reducing browning in many fresh-cut fruits and vegetables (Ahvenainen 1996; Buta and others 1999; Son and others 2001; GonzalezAguilar and others2001; Gorny and others 2002). The most frequent alternative to sulphite is ascorbic acid which is generally recognized as safe (GRAS) antioxidant for being used in fruits and vegetable to prevent browning by the US Food and Drug Administration (FDA). However, its effect is temporary (Özoğlu and Bayındırlı 2002) so that other alternatives should be found to control browning. In this sense, several...