Application of cassava starch and carnauba wax-based edible coatings in minimally processed apples / Aplicação de coberturas comestíveis à base de fécula de mandioca e cera de carnaúba em maçãs minimamente processadas

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

12/12/2011

RESUMO

This study aimed at formulating a cassava starch, carnauba wax and stearic acid or palmitic acid - based edible coating, and evaluating their properties and their effects when applied to minimally processed apples. In a first step, Plackett-Burman designs were performed for the following variables selection of coating formulations: cassava starch concentration (1 - 3% w/w), glycerol percentage (0 - 2% w/w), carnauba wax and fatty acid ratio (0.16:0.84 ¿ 0.64:0.36% w/w), stirring speed (8000 - 16000 rpm) and emulsification time (1-5 minutes). The variables cassava starch concentration (2-4% w/w), glycerol percentage (1- 3% w/w) and carnauba wax: fatty acid ratio (0:0 to 0.40:0.60% w/w) were selected to compose two composite central rotational designs 2³ (CCRD), one for carnauba wax and stearic acid and the other for carnauba wax and palmitic acid, setting the emulsification time and stirring speed in 3 minutes and 12,000 rpm, respectively. The designs aimed at the coating formulations selection by evaluating physical stability and average lipid particle size of filmogenic solutions, mechanical properties, color, solubility and moisture of films, respiration rate of coated apple slices, surface solid density and water vapor resistance of coatings applied to apple cylinders. Four formulations with stearic acid in the optimized region were selected for the validation procedure. The formulation elaborated with 3% (w/w) of cassava starch, 1.5% (w/w) of glycerol, 0.2% (w/w) of carnauba wax and 0.8% (w/w ) of stearic acid was selected for the shelf life study, since it showed coatings with good barrier properties, good stability and distribution of lipids in the emulsion and films with good optical, mechanical, thermal, physical and structural properties. In the shelf life study of minimally processed apples, the following treatments were applied in samples: control (samples only sanitized); ACAA (immersion in 1% citric acid and 1.5% ascorbic acid), FM (immersion in citric and ascorbic acids solution and coating with 3% cassava starch and 1.5% glycerol) and FMC (immersion in citric and ascorbic acid solution and coating selected in the experimental design validation). The treatments effects on respiration rate, weight loss, mechanical properties, color, soluble solids, pH, total acidity, vitamin C, water activity, moisture, cell structure, microbial growth and sensory acceptance of sliced apples stored at 5 °C for 12 days, and the determination of packaging gas composition were evaluated. The citric and ascorbic acid application was effective in reducing enzymatic browning, and its association with the cassava starch and lipids based coating promoted effective decrease in respiration rate, weight and vitamin C loss, maintenance of mechanical properties and cellular structure. The lipids addition to FMC treatment did not affect taste or aroma of samples, achieving a shelf life of 5 days sensory attested. The ACAA and FM samples did not differ statistically from the control in most analysis, except on color maintenance and reduction of vitamin C loss due to the use of antioxidants, also obtaining a shelf life of 5 days. The control showed great enzymatic browning and texture loss, and was sensory rejected after 1 day of storage

ASSUNTO(S)

microestruture maçã (malus domestica borkh.) coberturas comestíveis biofilme microestrutura vida util apple (malus domestica borkh.) edible coatings biofilm shelf life

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