Microemulsion based coatings with calcium and antioxidant for reducing chilling injury of ananas comosus
Loading...
Date
2020
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Teknologi Malaysia
Abstract
Ananas comosus generally known as pineapple is one of Malaysia’s commodity and commercially cultivated across various region in Malaysia. A highquality pineapple is valued from both its internal and external quality attributes. The standard postharvest practice and storage by refrigeration is recommended for perishable commodities which includes pineapple. However, cold storage causes physical and chemical deterioration known as chilling injury (CI). Although certain pineapple cultivar had been genetically developed with resistance toward CI, the findings of this study showed that CI affected quality attributes of all cultivars tested i.e. Morris (Queen), Josapine (hybrid of Spanish and Smooth Cayeen) and MD-2 (hybrid of Smooth Cayeen), regardless of their genetic makeup. Therefore, this research aims to develop a stable and edible microemulsion loaded with calcium chloride and clove essential oil which objectively to minimize the CI and maintain the quality attributes of pineapple both chemically and physically. An optimized microemulsion formulation with particle size of 203.22 nm, zeta potential (ζ- potential) of +3.65 mV and emulsion stability index (ESI) of 24.1 was obtained by applying 0.01% w/w whey protein isolate, 0.13% w/w carboxymethyl cellulose at pH 4.96. This optimized condition and formulation was obtained via response surface methodology. Characterization of optimum microemulsion was conducted morphologically and physically, and a stable microemulsion was observed for 30 days in response of size particle, ζ-potential and ESI. In overall, microemulsion coating performance results suggest that this coating significantly improved most of the quality attributes, antioxidant activity and storage capacity of the pineapples up to 30 days of storage at 4 ± 2 °C. Coated pineapples sustained up to 21 days with minimum effects of CI as compared to control which only capable to tolerate up to 7 days. A significant decrease in calcium content was found based on soluble calcium content and stained calcium localization qualitatively proven the occurrence of CI. The orthogonal testing to support this finding was by GC-MS primary metabolite analysis, in which coated pineapple showed greater shifts in metabolism by presence of distinctive amino acids and significant higher level of organic acids, soluble sugar and soluble alcohol as indicator of response to chilling stress and adaptive mechanisms.
Description
Thesis (PhD. (Bioprocess Engineering))
Keywords
Pineapple, Fruit—Frost protection, Fruit—Handling