Effects of sodium metabisulphite and citric acid on the shelf life of fresh cut sweet potatoes

Abstract

Minimally processed vegetables are products susceptible to chemical and biological changes, thus becoming highly perishable. During sweet potatoes (Ipomoea batatas Lam.) processing, some deteriorative reactions occur affecting quality, mainly change of color. The purpose of this research is to avoid or minimize this deterioration, so the effects of application of chemical agents to fresh cut and refrigerated stored sweet potatoes were studied, evaluating the occurrence of major organoleptic, physicochemical and nutritional changes and assesing the sensory acceptability. Tests were done with sweet potato variety 'Colorada Correntina', which were treated with sodium metabisulphite/citric acid (pH = 2.91), arranged in polystyrene trays film, coated with PVC, and stored at 5°C and 10°C. Variations on the titratable acidity, pH, total sugars and ascorbic acid were registered and the surface color was evaluated through digital image analysis. The final product acceptability was determined through sensory evaluation and microbiological counts carried out at the beginning and at the end of the assays. During storage, there were slight changes in physicochemical characteristics such as absorbic acid and sugar content and in surface color as well. The microbial counts were lower than the fixed levels established by the Spanish legislature. The sensory attributes were rated as «accep-table» by consumers. Finally it is possible to assert that sweet potato 'Colorada Correntina' minimally processed and treated with sodium metabisulphite 2%/citric acid can be preserved, packaged and stored at 5°C for 14 days.Additional key words: browning, Ipomoea batatas, physicochemical characteristics, sensory evaluation. Resumen Efectos del tratamiento químico en la vida útil de batatas frescas cortadasLos vegetales mínimamente procesados son productos susceptibles a alteraciones fisicoquímicas y biológicas, resultando altamente perecederos. Durante el procesamiento de batatas (Ipomoea batatas Lam.), ocurren reacciones de deterioro que afectan la calidad, especialmente el cambio de color. Con el objeto de evitar o minimizar este deterioro, se estudiaron los efectos de la aplicación de agentes químicos a batatas frescas cortadas almacenadas refrigeradas, evaluando la ocurrencia de los principales cambios organolépticos, fisicoquímicos y nutricionales, y estableciendo la aceptabilidad sensorial. Los ensayos se realizaron con batatas variedad 'Colorada Correntina', tratadas con sodio metabisulfito/ácido cítrico (pH = 2,91), dispuestas en bandejas de poliestireno recubiertas con film de PVC, y conservadas a 5°C y 10°C. Se registraron las variaciones de pH, acidez titulable, azúcares totales y ácido ascórbico y se evaluó el color superficial por análisis de imágenes digitales. Mediante evaluación sensorial se determinó la aceptabilidad del producto final y se realizaron recuentos microbiológicos al inicio y final de los ensayos. Durante el almacenamiento ocurrieron ligeros cambios en las características fisicoquímicas, el contenido de a...

Effects of pretreatment during drying on the antioxidant properties and color of selected tomato varieties

“…This indicated that chemical pretreatment was preventive against oxidation that is characterized by formation of darkened products. It has been reported that sulfites reduce o‐quinones to colorless di‐phenols thus prevent browning (Sgroppo, Vergara, & Tenev, ). The low luminosity in the control samples was indicative of possible darkening that is characteristic of enzymatic and nonenzymatic reactions that occur during heat processing Luterotti, Bicanic, and Markovi() therefore, indicating that the effect of 0.5% N.M in mitigating darkening was greater compared to that of the control and 0.5% C.C.…”

“…This corresponds to maximum percentage retention of 60%, 71%, and 80% for the corresponding chemical pretreatments relative to the fresh. The higher minimization of phenolic degradation through pretreatment as compared to the control may be attributed to the ability of sodium metabisulfate and calcium chloride to retard oxidative reactions and tissue damage (Sgroppo et al., ) that may cause irreversible changes in the quality of dried produce. On the other hand, the percentage retention was 27%–59%, 42%–69%, 31%–61%, and 35%–80% for Anna F1, Kilele, Prostar F1, and Riogrande variety, respectively, depending on the drying temperatures and chemical pretreatment applied.…”

Utilization of physicochemical variables developed from changes in sensory attributes and consumer acceptability to predict the shelf life of fresh-cut mango fruit

“…Moreover, polynomial equations with determination coefficients higher than 0.9 were developed to predict the sensory quality of mango fruit from textural changes for all cultivars with the exception of one (Jha et al 2011b) However, a methodology to obtain cut-off points for the physicochemical variables based on sensorial analysis has not been reported for fresh cuts. Instead, subjective analysis of the organoleptic quality changes had been used in several studies to know the shelf life of these products (Beaulieu and Lea 2003;Sothornvit and Rodsamran 2010;Sgroppo et al 2010;Chiumarelli et al 2010).…”

Effects of Sodium Metabisulphite and Blanching Pretreatments on the Quality Characteristics of Yam Bean (Pachyrhizus erosus) Flour

“…Sulphite inhibits enzymatic browning by reducing o-quinones to colourless diphenol [10,11] or by reacting irreversibly with o-quinones to colourless products [12]. Sulphur dioxide and its derivatives (sulphite, bisulphite and metabisulphite) are oxidizing agents that act as preservatives and stabilizers in some products but cause allergies to some people [11].…”