Volatile aroma and physicochemical characteristics of freeze-dried coconut water using different encapsulating agents.

This research studied how different types and concentrations of encapsulating agents impacted freeze-dried coconut water products. Volatile aroma and physicochemical product characteristics were evaluated. The encapsulating agents were maltodextrin 4-8% (w/v), polydextrose 4-8% (w/v) and xanthan gum 0.1-0.3% (w/v). A plate freezer and an air blast freezer were used to pre-freeze the coconut water before drying. Freezing time had no impact on moisture content and water activity. The flavor compounds of coconut water is composed of alkanes, aldehyde, ketones, organic acids and some other flavor substances. Encapsulating agents are the main factors affecting the flavor of coconut water. Optimal conditions for producing dried coconut water were adding polydextrose at a concentration of 8%. Volatile compounds were assessed under different conditions of SPME- GC-TOFMS. The composition of flavor compounds in coconut water is complex and mainly includes esters, aldehydes, and phenols. Results showed that encapsulating agents improved the volatile aroma of dried coconut water products.

Impact of protectants on the storage stability of freeze-dried probiotic Lactobacillus plantarum.

The ability of rice protein supplemented with various prebiotics to protect probiotic Lactobacillus plantarum TISTR 2075 upon freeze-drying and subsequent storage was determined. A combination of rice protein-fructooligosaccharide (RF) provided the best storage stability with the lowest specific rate of cell death (k) of 1.20 × 10-2 and 5.79 × 10-2 1/day during subsequent storage at 4 °C for 180 days and 30 °C for 90 days, respectively. Glass transition temperatures (T g) of freeze-dried probiotic in various protectants were 14.2-25.4 and 42.9-50.1 °C after storage at 4 and 30 °C, respectively. The functional properties of freeze-dried probiotic with protectants remained stable. The presence of RF could effectively protect and enhance the probiotic functionality during exposure to gastrointestinal tract conditions. The pathogenic inhibition of freeze-dried probiotic against foodborne pathogens was not different from the active cells. Protective agents were able to maintain high degrees of cell surface hydrophobicity.