Application of Alginate and Agar-based Edible Coatings to Pre-cut Jackfruit and Evaluation of the Flavor Compounds of Coated Pre-cut Jackfruit during Refrigerated Storage.

Abstract

Jackfruit (Artocarpus heterophyllus Lam) is in high demand by Asians. It is large and difficult to peel, therefore, consumers prefer to buy jackfruit as a ready to cook product. Jackfruit is highly perishable. It ripens faster during the shelf life, and soon become unfit for cooking. Development of volatile compounds which contribute to flavour and aroma takes place during the ripening process. The aim of this study was to investigate the effect of application of 1% alginate-based and agar-based edible coatings on retention of volatile compounds developed in pre-cut jackfruit during a shelf life of 5 days under refrigerated conditions (6+10C). The alginate coating was developed by dissolving alginate and glycerol in distilled water. CaCl2 was used as a cross-linking agent in the alginate-based coating. The agar coating was also developed by dissolving agar and glycerol in water. Jackfruit of initial brix 6.23 + 0.39 were selected for the study. Volatile compounds were detected by SPME-GC-MS technique on a DB-225MS column in uncoated, alginate coated and agar coated jackfruit on the 2nd day and 5th day of the shelf life. Esters, benzenic derivatives, pyridine derivatives, volatile alkanes, volatile alkenes, terpenes, aldehydes, ketones and alcohols were detected during the analysis. Compounds which were detected only from alginate coated samples were 1,2-dichlorobenzene, dimethyl(4- bromo-phenoxy)pentadecyloxy silane, 1,4-dihydro-1,4- methanonaphthalene, 4-(1-methyl-2-pyrrolyl)-2,6- diphenylpyridine, vanillin, trans-octahydro-1H-inden-1-one, and dimethyl-silanediol. These can be attributed as volatile compounds related to alginate. Compounds like 2,5-bis(1,1- dimethylethyl)phenol, tetradecanal, hexadecanal and transdodec- 5-enal were only detected from agar coated samples. These can be attributed as volatile compounds related to agar. Volatile compounds like 6-methyl-2-heptanone, naphthalene, tridecane, tetradecane, pentadecane and hexadecane were lost from the uncoated jackfruit sample during the shelf life and these compounds could be preserved in pre-cut jackfruit by the applied alginate and agar coatings.