Quality Evaluation and Rehydration Characteristics of Dried Lotus Root Slices

Ho, See Mun (2024) Quality Evaluation and Rehydration Characteristics of Dried Lotus Root Slices. Final Year Project (Bachelor), Tunku Abdul Rahman University of Management and Technology.

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Abstract

The root of the lotus plant (Nelumbo nucifera) has an abundance of beneficial phytochemicals but it has a short shelf life due to its high moisture content. Investigation of drying parameters is essential to retain much of the nutrients in the dried lotus root slides. This study aimed to determine the effects of drying temperature (40 ℃, 50 ℃ and 60 ℃) and drying time (16 hours, 20 hours and 24 hours) on the physicochemical properties (moisture content, water activity, colour, texture, shrinkage and ascorbic acid content), total phenolic content (TPC), total flavonoid content (TFC), antioxidant activity (DPPH and ABTS) and rehydration ratio of dried lotus root slices. Subsequently, the rehydration ration characteristic of lotus root slices dried at optimised drying temperature and time was investigated for hydration temperatures of 40 ℃, 60 ℃ and 80 ℃ in a duration of 5 hours. The results showed that drying temperatures and time significantly affected (P < 0.05) moisture content, water activity, L*, b*, colour change, hardness, springiness, gumminess, chewiness, cohesiveness, shrinkage, ascorbic acid content, TPC, TFC, DPPH, ABTS and rehydration ratio. The optimised drying temperature and time were determined as 50 ℃ and 16 hours, which yielded dried lotus root slices with 17.99 % of moisture content, 0.6813 of water activity, 30.19 % of shrinkage, 51.70 of L*, 9.233 of a*, 15.97 of b*, 14.89 of colour change, 3186.94 g of hardness, 1.207 of springiness, 3444.00 g of gumminess, 4013.99 g of chewiness, 1.084 of cohesiveness, 193.86 mg ascorbic acid/100 g dry solids of ascorbic acid, 105.9 mg GAE/100 g dry solids of TPC, 3.218 mg QE/100 g dry solids of TFC, 218.9 mg AAE/100 g dry solids of DPPH, 240.7 mg TE/100 g dry solids of ABTS and 2.557 of rehydration ratio. The highest rehydration ratio of 4.931 was obtained in the optimised dried lotus root slices which was rehydrated at 80 ℃ for 5 hours. This study gives an insight of the importance of proper drying parameters to preserve the lotus root slices for good product quality.