Effects of pectin-carboxymethyl cellulose-based coatings containing antibrowning agents on some physico-chemical properties of fresh-cut Red Delicious apples

Coating of fresh-cut fruits by biopolymer coatings containing bioactive materials are one of the methods and effective ways to prevent undesirable quality changes during storage. Enzymatic browning is an important factor in reducing the shelf-life of freshly squeezed apples, which is due to the release of the enzyme and its contact with the substrate (phenolic matter) through the cutting. Formulation and production of active carboxymethylcellulose-pectin-based active coatings containing citric acid and ascorbic acid and their effectiveness in improving the qualitative characteristics of apple peelings, which have been peeled during storage. In the present study, natural substances found in fruits were used for coatings formulations and a mixture of pectin-carboxy methyl cellulose polysaccharides as based biopolymers and ascorbic acid and citric acid were used as materials inhibited enzymatic browning. Measured tests include determination of weight loss Samples were weighed after 9 days of storage in cold storage. Also, tissue texture determination and determination of tissue firmness using a manual pentometer, soluble solids content (Bx) with refractometer, titreable acidity in malic acid in 100 ml of juice, colorimetry of samples using a device The colorimetric method was evaluated based on Hunterlab's parameters and Photoshop software and Sensory Hedonic test (consumerism) by 10 randomized (from female students 22 to 25 years old) and 5-point method. At first, optimization of active-blend edible coating formulation was investigated by response surface methodology (RSM) based on the minimum a * (red - green) in fresh-cut apples and for this purpose, central composite design with three variables (concentration of carboxymethyl cellulose-pectin, ascorbic acid and citric acid) three replicate and 18 treatments were used. In this way, the coating solution of containing 3.14% carboxymethyl cellulose-pectin, 1.17% ascorbic acid and 1.17% citric acid (%w/v) was determined as best coating solution. Then effects of optimized coating on quality of fresh-cut apples were studied. Although there is no significant difference among coated and uncoated apples after 9 days (P<0.05) but the results of firmness test showed that coated fresh- cut apples maintain initial texture better than control. The acidity values were higher in coated apples compared to un coated apples (0.41 and 0.17, respectively). Coating caused to decrease in overall color change of fresh-cut apples after 9 days. The use of coating resulted to better flavor, texture, color, aroma and appearance acceptability in comparison to the control sample and there is a significant difference at the 5% level between the samples. Comparison of the data on the content of soluble solids in coated and uncoated peelable apples showed that the difference was not significant at 5% level. Hunter's colorimetric parameters were compared to the coated peelable apples and uncoated samples at day 1 and ninth of storage. ∆E in fact, the degree of color difference shows the samples of the ninth day with the first day. The values of ∆E for the coated sample are lower, the values of the color parameters (a, b and L) are less pronounced in the coated sample than in the first day. Edible coatings can delay the progress of this reaction by reducing the contact of oxygen with fruit tissue, as well as the presence of anti-browning agents such as ascorbic acid and citric acid in active coatings, exacerbating the inhibitory effect. Which can reduce the pH and hence decrease the activity of the enzyme in the phenolase and make the copper cofactor chelate. The results of the Hedonic evaluation of peeled apples showed that there was a significant difference in the level of 5% between the final color absorbance of coated samples and uncoated samples. Sensory evaluators significantly increased the scoring of the samples and more accurately recognized it. The results of analysis of variance showed that the final aromas of freshly squeezed apples were affected by the coating and prevented the decrease in aroma. After 9 days of storage, the taste of the coated samples was score higher.