EFFECT OF SELECTED ORGANIC ACIDS ON THE PROPERTIES OF Borassus aethiopum STARCH-BASED FILMS FOR FRUITS AND VEGETABLE STORAGE

Abstract

The increasing use of synthetic polymers to preserve foods is of more concern to the society. Edible coatings serve as the best alternative to reduce the post-harvest losses by delaying the ripening of fruits and vegetables and increasing the shelf life without affecting the quality. The study investigates the effects of formic, acetic, lactic, butyric, pentanoic and citric acids on Borassus aethiopum starch-based films for fruits and vegetable storage. Starch was extracted from Borassus aethiopum shoot using wet extraction method. Starch-based films were produce by casting method with the incorporation of six organic acids (Formic, acetic, lactic, butyric, pentanoic and citric acids) having five concentrations (0.2 %, 0.4 %, 0.6 %, 0.8 % and 1 %) each. Biodegradability test of starch-based films was carried out using soil burial test and antimicrobial activities of the starch-based films were carried out using agar diffusion method. Shelf-life determination of tomato, banana and spinach was carried out using dipping method. The result showed that Borassus aethiopum had (64.24%) starch content and the six organic acids incorporated had better film forming property. Borassus aethiopum starch-based films incorporated with organic acids had improved biodegradability and water absorption capacity. The antimicrobial inhibitory activities of the starch-based films incorporated with citric and lactic acids at 1 % concentration showed that citric acid films had highest inhibitory activity (1.85 ± 0.05) followed by lactic acid (3.97 ± 0.07) at p ≤ 0.05 when compared with the control sample (9.57 ± 0.08) for E. coli). For klebsiella pneumonia inhibition, citric acid and lactic acid showed significant (p ≤ 0.05) inhibitory effect at 1% concentration (1.31 ± 0.06 and 4.60 ± 0.03) respectively when compared with the control (8.66 ± 0.06). There was significant p ≤ 0.05 improvement in the tensile strength and elongation at break of both citric acid and lactic acid films when compared with the control sample. The shelf-life of stored coated tomato, banana and spinach with citric and lactic acids at 1 % concentration was found to be extended up to 30 days for tomatoes, 10 days for banana and 4 days for spinach. The coated samples were firmer, fresh looking and less decayed when compared with the uncoated samples (control) at the end of the storage. It can be concluded from the results obtained that Borassus aethiopum starch could be a good source of starch for film production and citric and lactic acids could be incorporated into it to increase the shelf life of fruits and vegetable