Effect of Methylcellulose and Carnauba wax coating with Modified Atmosphere Packaging on the improvement quality of Red Delicious apple

  The quality of fresh fruits and vegetables, and thus their shelf life, is reduced due to changes such as moisture loss, enzymatic browning, tissue decay, and microbial growth. The use of an edible coating on fruits and vegetables during storage will increase shelf life by controlling the moisture migration, respiration rate, and oxidation. As apple is one of the most important raw materials for many foods and is grown in many countries around the world, it is important to keep apples fresh. The use of methylcellulose and Carnauba wax coating with Modified Atmosphere Packaging for maintaining the quality and prolonging the shelf life of Red Delicious apples.

 In this study, fresh apples (Red Delicious) were coated by two types of coating materials (methyl cellulose and carnauba wax) then samples packed in three layers bags (PE/PA/PE) with normal air condition (control), active modified atmosphere and inactive (passive) modified atmosphere, Samples stored at 2°C for 3 month. Thereafter, their quality characteristics such as Weight losses, color changes, hardness and change in packaging gas percentage, were tested and evaluated.  

Data showed coated samples had better properties as compared to the uncoated samples. The property was more obvious in samples coated by methylcellulose. In coating samples, weight losses were significantly (P≤0.05) less than uncoated samples, and also weight loss was slower.  At the end of the storage time, the highest firmness (958.2) was related to the sample with methyl cellulose coating and the lowest firmness (780.2) was related to the sample without coating (control). In the methyl cellulose coated samples, the weight loss of the samples was significantly lower than the other samples and the weight loss occurred at a slower rate (p≤0.05). At the end of the third month, the highest (7.6) and the lowest (4.7) weight loss was related to the sample without coating and the sample with methylcellulose coating, respectively. At the end of the sample storage time, the uncoated sample (control) had the highest Brix (17.2) and the sample coated with carnauba wax (16.1) had the lowest Brix. In all samples, the amount of L* decreased at the end of the storage time. During the entire storage period of apples, the amount of L* of the coated samples was higher than that of the control samples. The amount of L* in the control samples decreased and reached (19.2), while it reached (25.6) in the samples with methyl cellulose coating.  

  The results of the present study showed that Methylcellulose was an appropriate coating to maintain the quality and increase the shelf-life of apples (Red Delicious).