Effect of Osmotic Agents on Freeze Dried Mango Powder

Lee, Man Yee (2019) Effect of Osmotic Agents on Freeze Dried Mango Powder. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

This research works on the optimisation of the partial drying with osmotic pre-treatment using different osmotic agents and followed by the comparison of the quality attributes between the non-pre-osmotic and optimised freeze dried mango powder. Mango was undergone osmotic pre-treatment with osmotic agent of different sugar concentration (0% – 60%) and brine concentration (0% – 30%) prior to freeze drying into mango powder. Response surface methodology was applied to obtain the optimum value based on the responses which include moisture content, solubility, ascorbic acid and DPPH radical scavenging activity assay. The second-order polynomial equations adequately described the quality of freeze dried mango powder with regression coefficient, R2 > 0.7. Moisture and solubility were good function of the combination effect of sugar and brine (P < 0.05) and (P < 0.005) respectively; while ascorbic acid and DPPH radical scavenging assay mainly influence by brine concentration (P < 0.005) and sugar concentration (P < 0.005), respectively. The optimum 4.24% of sugar concentration and 0% of brine concentration was determined using the desirability function method with desirability value was 0.8066 for target moisture content, maximum solubility, ascorbic acid and DPPH radical scavenging activity. Non-pre-osmotic and optimised freeze dried mango powder was compared with the antioxidant and physicochemical properties. DPPH, FRAP, TPC and TCC of optimised freeze dried mango powder were significantly increased (P < 0.05) by 6.70%, 18.45%, 9.52% and 20.37%, respectively compared to non-pre-osmotic mango powder. The moisture content and pH value gives a positive reading in optimised sample. Optimised freeze dried mango powder has also a better sweet taste than the non-pre-osmotic freeze dried mango powder revealed in the qualitative descriptive analysis (P < 0.05). The optimised freeze dried mango powder could be enhanced further with more investigations.