Wax- based edible coatings for strawberry fruit

Abstract

Wax-based edible coatings for strawberry fruit were formulated and optimized. The weight loss was the preliminary quality parameter for determining the appropriate composition of the waxbased coating. Different combinations of wax to coconut oil ratio and amount of ethanol were performed to create a coating solution that would result in reduction of the weight loss while giving a desirable appearance. After conducting the preliminary study, it was concluded that the combination of 4 wax: 1 coconut oil in 70 mL ethanol was the best combination in order to significantly reduce the weight loss. Beewax and candelilla wax were used as the wax-basis, with coconut oil in the ratio 4:1. Both types of coating were applied onto strawberry fruits and these were evaluated for weight loss, surface color, ascorbic acid content, decay incidence, yeasts and mold count. A sensory evaluation was also performed. Strawberries were stored for 10 days at 10ºC. Both wax-based coatings produced significant reduction in weight loss in comparison to the uncoated fruits. Furthermore, a significant decrease of 20% and 15% in the reduction of ascorbic acid was noted on the 7th day of storage, for beewax - coconut oil coating and candelilla wax - coconut oil coating, respectively. The presence of mycelial growth often dictates the shelf-life of the strawberry fruit. In this study, a significant reduction in the decay incidence was observed both in beewax-coconut oil and candelilla wax-coconut oil coating. This was further supported by the lower yeast and mold count obtained for the coatings used. The changes in color between coated and uncoated fruits were not significantly different except for the L*value with higher values for coated fruits. In the sensory evaluation of the uncoated and coated fruits, judges also distinguished the color between the control and the treated fruits, after two days of storage at 4ºC. Significant differences were also noticed between fruits coated with candelilla wax- coconut oil and the control, regarding other sensory parameters. However, there were not significant differences between beewax-coconut oil based coating and the uncoated fruits. Edible wax-based coating of beewax-coconut oil and candelilla wax-coconut oil could help to extend the shelf life of strawberry since after 10 days of storage the yeasts and molds count was 4.0 × 105 cfu/g and 5.3 × 105 cfu/g for beewax-based and candelilla wax-based coated samples, respectively, lower than 9.4 × 107 cfu/g for the uncoated ones. However, those counts are still high, indicating a shelf life of beewax-based and candelilla wax-based coated strawberries shorter than 10 days.

Date of Award	2014
Original language	English
Awarding Institution	Universidade Católica Portuguesa
Supervisor	Alcina M. M. Bernardo Morais (Supervisor) & Rui M. S. C. Morais (Co-Supervisor)