Optimizing sugar stability and antioxidant retention in dehydrated grape pomace using pre-treatments and packaging

Abstract

The study evaluated the combined effect of chemical pre-treatments and packaging materials on sugar stability and retention of bioactive compounds in solar-dehydrated grape pomace (cv. Bangalore Blue). Grape pomace was pre-treated with potassium metabisulphite (KMS), citric acid and calcium chloride, alone or in combination, solar dehydrated, powdered and packed in low density polyethylene (LDPE), metallised polyester and an unpacked control. Samples were stored under ambient conditions and analyzed at 0, 30, 60 and 90 days for reducing and total sugars, while total polyphenols and anthocyanins were estimated after dehydration. Citric acid (1%) + KMS (0.5%) recorded the highest retention of total polyphenols and anthocyanins. Reducing sugars increased and total sugars decreased during storage in all treatments; however, metallised polyester packaging minimized these changes, followed by LDPE, while the control showed maximum deterioration. The interaction effect was significant for reducing sugars and non-significant for total sugars. The combined application of citric acid (1%) + KMS (0.5%) and metallised polyester packaging was most effective in maintaining sugar stability and antioxidant quality of grape pomace powder during ambient storage, highlighting its potential as a functional food ingredient.